Improved separation of rare earth elements using hydrophobic deep eutectic solvents: liquidliquid extraction to selective dissolution


Enhancement of the Catalytic Activity Associated with Carbon Deposition Formed on NiO/γ-Al2O3 Catalysts during the Direct Dehydrogenation of Isobutane

The dehydrogenation of isobutane in the presence of CO2 over NiO supported on γ-Al2O3 was examined. For comparison, Cr2O3 supported on γ-Al2O3 was also used. It is generally accepted that a catalyst used for the dehydrogenation of various alkanes will suffer catalyst deactivation due to the formation of carbon deposits. In the present study, the yield of isobutene was significantly decreased with time-on-stream due to carbon deposition when using Cr2O3(x)/γ-Al2O3, in which x indicates the loading of a corresponding oxide by weight %. However, carbon deposits also were evident on NiO(x)/γ-Al2O3, but the yield of isobutene was enhanced with time-on-stream depending on the loading (x). This indicates that the contribution of the carbon deposition in the dehydrogenation on NiO(x)/γ-Al2O3 definitely differed from that on an ordinary catalyst system such as Cr2O3(x)/γ-Al2O3. In order to confirm the advantageous effect that carbon deposition exerted on the yield of isobutene, NiO(x)/γ-Al2O3 was first treated with isobutane and then the catalytic activity was examined. As expected, it became clear that the carbon deposits formed during the pretreatment contributed to the enhancement of the yield of isobutene. The presence of a Ni-carbide species together with the metallic Ni that was converted from NiO during dehydrogenation definitely enhanced of the yield of isobutene. Although carbon deposition is generally recognized as the main cause of catalyst deactivation, the results of the present study reveal that carbon deposition is not necessarily the cause of this phenomenon.

Journal of Chemical Engineering of Japan


Dependence of Phosphorus Recovery on Acid Type during Dissolution-Precipitation Treatment of Incineration Ash of Chicken Manure

In order to utilize chicken manure as a source of phosphorus, we used dissolution-precipitation treatment to recover phosphorus from the incineration ash of chicken manure (IACM), which was used as fuel to power a boiler. In order to recover useful phosphorus-containing solids from IACM, it was dissolved into aqueous solutions of either nitric acid, hydrochloric acid, or sulfuric acid to elute phosphorus together with various component elements, followed by the use of aqueous NH3 to form a precipitate containing phosphorus. In using nitric acid and hydrochloric acid, calcium phosphate species such as calcium hydroxyapatite (Ca10(PO4)6(OH)2) and monetite (CaHPO4) were obtained following the precipitation treatment. By contrast, the use of sulfuric acid resulted in the precipitation of magnesium ammonium phosphate (MAP) species such as struvite (MgNH4PO4∙6H2O) and dittmarite (MgNH4PO4∙H2O). Both the calcium phosphate and MAP species can be used as a slow-acting fertilizer containing phosphorus, while the MAP species could be simultaneously used as a slow-acting fertilizer containing nitrogen. It is noteworthy that the calcium phosphate species obtained in the present study was equivalent to phosphate rock, which is widely used as a raw material in phosphorous-based industries, and the natural sources of this material could be depleted in the near future. Though IACM has not been used effectively until now, this new resource shows promise as s viable alternative to the dwindling supply of the natural sources of phosphorus.


Effect of Cerium Addition to Bismuth-molybdenum Complex Oxide Catalyst for Partial Oxidation of Propylene to Acrolein

Ce addition to a Bi-Mo complex oxide catalyst supported on SiO2 was examined for its effect on the partial oxidation of propylene to acrolein. The catalyst consisted of an oxygen-supply phase where the lattice oxygen in Mo-oxide was doped with transition metals such as Fe, Ni and Co and was supported by SiO2 and a catalytic-active phase that involved hydrogen-abstraction from a reactant in the Bi-center of Bi-Mo oxide, which was supported by an oxygen-supply phase. In the present study, Ce was added during the oxygen-supply phase in order to enhance its redox nature. An advanta-geous effect of Ce addition was observed particularly under oxygen-rich conditions in the feed stream. For example, at P(C3H8) = 10.1 kPa and P(O2) = 15.5 kPa at 623 K, the yield of acrolein was slightly enhanced from 57.6% with 0% Ce doping to the catalyst to 65.3% with 20% Ce doping to the catalyst at 6 h on-stream. However, under greater oxy-gen-rich conditions at P(C3H8) = 10.1 kPa and P(O2) = 31.0 kPa at 623 K, the yield of acrolein was enhanced approxi-mately twice from 27.7% with 0% Ce doping of the catalyst to 61.8% with 20% Ce doping of the catalyst at 6 h on-stream. Analysis using XPS for the catalysts previously used for the reaction in the absence of gaseous oxygen con-firmed the unique redox behavior between the catalytic-active phase and the oxygen-supply phase as the lattice oxygen in the catalytic-active phase was replenished from the oxygen-supply phase to maintain its surface properties over the catalytic-active phase. The XPS results and the remarkable effect of Ce addition to the oxygen-supply phase under ox-ygen-rich conditions confirmed the correctness of the concept of the catalyst preparation consisting of an oxy-gen-supply phase and a catalytic-active phase was correct.

SiO2に担持されたBi-Mo複合酸化物触媒へのCe添加の効果を，プロピレンのアクロレインへの部分酸化について検討した．本研究で検討した触媒は2つの相で構成されおり，SiO2に担持されたMo-酸化物にFe, Ni, Coを導入した格子酸素に対する酸素供給相，およびその周りに担持した反応物からの水素引き抜きを行うBiサイトを持つBi-Mo酸化物の触媒活性相の2相である．本研究では，酸素供給相の酸化還元性を高めるために，酸素供給相にCeを添加した． Ce添加による良好な結果は，酸素リッチの原料ガスを用いた際に観測された．例えば，P(C3H8) = 10.1 kPa，P(O2) = 15.5 kPa，T = 623 K，通塔時間6時間において，Ceの添加率が0%から20%に増加させても，アクロレインの収率は，57.6%から65.3%へわずかに増加しただけであった．一方，同条件で，P(O2) = 31.0 kPaとした酸素リッチ条件では，Ceの添加率が0%から20%に増加させると，アクロレインの収率は，27.7%から61.8%へと約2倍増加した．原料ガス中に酸素を加えずに反応を繰り返した後の触媒のXPS分析により，触媒活性相と酸素供給相の間のユニークな酸化還元挙動が確認され，触媒活性相の格子酸素は酸素供給相から補充されて，触媒活性相表面の状態が維持されることが明らかになった．これらのXPSによる結果と，酸素リッチ状態での酸素供給相へのCe添加の触媒活性への顕著な効果に基づいて，酸素供給相と触媒活性相からなる触媒調製方法の概念が正しいことを明らかにした．

Journal of the Japan Petroleum Institute


Oxidative Dehydrogenation of Methane When Using TiO2- or WO3-Doped Sm2O3 in the Presence of Active Oxygen Excited with UV-LED --- Special Issue: Photocatalytic Oxidation/Ozonation Processes

There are active oxygen species that contribute to oxidative coupling or the partial oxidation during the oxidative dehydrogenation of methane when using solid oxide catalysts, and those species have not been definitively identified. In the present study, we clarify which of the active oxygen species affect the oxidative dehydrogenation of methane by employing photo-catalysts such as TiO2 or WO3, which generate active oxygen from UV-LED irradiation conditions under an oxygen flow. These photo-catalysts were studied in combination with Sm2O3, which is a methane oxidation coupling catalyst. For this purpose, we constructed a reaction system that could directly irradiate UV-LED to a solid catalyst via a normal fixed-bed continuous-flow reactor operated at atmospheric pressure. Binary catalysts prepared from TiO2 or WO3 were either supported on or kneaded with Sm2O3 in the present study. UV-LED irradiation clearly improved the partial oxidation from methane to CO and/or slightly improved the oxidative coupling route from me-thane to ethylene when binary catalysts consisting of Sm2O3 and TiO2 are used, while negligible UV-LED effects were detected when using Sm2O3 and WO3. These results indicate that with UV-LED irradiation the active oxygen of O2 from TiO2 certainly contributes to the activation of methane during the oxidative dehydrogenation of methane when using Sm2O3, while the active oxygen of H2O2 from WO3 under the same conditions afforded only negligible effects on the activation of methane.

本研究は，酸素流通下でUV-LED照射すると活性酸素を生成するTiO2やWO3などの光触媒を用いて，どのような活性酸素種がメタンの酸化脱水素に影響を与えるかという点を解決する一環として行われた．常圧固定床流通式反応装置を用い，大気圧下で直接UV-LEDを固体触媒に照射できる反応系を構築した．触媒には，メタン酸化カップリング触媒であるSm2O3とTiO2またはWO3から二元系触媒を選択し，それぞれ担持法および混練法で調製した．Sm2O3とTiO2からなる二元系触媒を使用した場合，UV-LED照射によりメタンからCOへの部分酸化が改善され，メタンからエチレンへの酸化カップリングもわずかに改善された．一方，Sm2O3とWO3からなる二元系触媒を使用した場合，UV-LED効果はほとんどなかった．UV-LED照射により，TiO2からの発生する活性酸素であるO2‒はSm2O3を使用する場合には，メタンの酸化脱水素におけるメタンの活性化に寄与するが，WO3から発生する活性酸素であるH2O2はほとんど効果を示さないと結論づけた．


Effects of different silica intermediate layers for hydrogen diffusion enhancement of palladium membranes applied to porous stainless steel support

Porous stainless steel (SUS) supports were modified with double intermediate layers, silicalite-1 and -alumina, to enhance the hydrogen diffusion of a thin palladium membrane. One of layers, silicalite-1, was prepared using the hydrothermal synthetic method on porous SUS supports. The differences in expansion/contraction behaviors caused by different thermal coefficients of expansion between silicalite-1 and the SUS resulted in a lowering of the durability of the membrane. Intermediates layers of mesoporous MCM-48 powders or commercial spherical non-porous silica particles were then applied to porous SUS supports via aspiration, -alumina was introduced by dip-coating, and the Pd membrane was subjected to electro-less plating. H2 permeance of the Pd membrane (membrane thickness: 11 m) containing spherical silica particles was around 10x10-6 molm-2s-1Pa-1 at 600°C, which was higher than that of the Pd membrane (membrane thickness: 7 m) containing MCM-48. The durability of the Pd membrane containing spherical silica particles was higher than that of the version containing MCM-48 powders. These results suggest that commercial spherical non-porous silica particles will uniformly occupy the pores of the SUS tubes and enhance the H2 permeance and durability of the Pd membrane.


Alkali Treatment of Commercial Silicoaluminophosphate Molecular Sieves (SAPO-34) Enhances the Water Adsorption and Desorption Properties

Commercial silicoaluminophosphate molecular sieves (SAPO-34) received alkali treatment with either NaOH (0.2, 0.01, 0.005, or 0.001 M) or NH4OH (0.005 M). Treatment with NaOH (0.005 M) increased the water adsorption initial rate of SAPO-34 by 1.4-fold. The alkali treatment introduced Na+ adsorption sites into the SAPO-34. The desorption ratio (adsorption at 30 and desorption at 100) was 88.2% higher than the original rate (84.3%). On the other hand, after alkali treatment of SAPO-34 using NH4OH (0.005 M), calcination resulted in the highest desorption ratio at 91.3%. When combined with calcination, alkali treatment with NH4OH introduced H+ adsorption sites into SAPO-34, H+ adsorption sites feature low levels of interaction with water, which enhanced the desorption ratio, but decreased the initial adsorption rate. These results indicate that treating commercial SAPO-34 with 0.005 M NaOH enhances both the adsorption and desorption behaviors.

Journal of Encapsulation and Adsorption Sciences


Catalytic Activity and Coking Resistance on Hydroxyapatite for the Oxidative Dehydrogenation of Isobutane


Recovery of Phosphate Rock Equivalents from Incineration Ash of Chicken Manure by Elution-precipitation Treatment

In order to obtain calcium phosphates - a phosphate rock equivalent - from the incineration ash of chicken manure, which is obtained from power generation systems that use the manure for fuel, incineration ash was treated with an aqueous solution of nitric acid to elute phosphorus. By using 0.3 M of HNO3, most of the phosphorus could be eluted from 1.0 g of ash within 0.1 h. Compared with the composted chicken manure that was previously examined in our laboratory, the concentration of HNO3 was increased for this session of elution. Using the incineration ash of chicken manure made it possible to remove inorganic species at a lower boiling or sublimation temperature, and organic species by calcination in the power generation system. Compared with composted chicken manure, the concentrations of phosphorus contained in the incineration ash and the nitric acid extract were higher in the incineration ash. XRD analysis showed that the obtained nitric acid extract could be treated with aqueous NH3 to form a precipitation of poorly-crystallized calcium hydroxyapatite (Ca10(PO4)6(OH)2), which is one of main components in phosphate rock. In order to confirm the formation and purity of calcium phosphate species, the precipitation calcination was conducted at 1,078 K for 5 h. XRD revealed that the calcined solid was tricalcium phosphate, and no contamination was evident. These results reveal that a phosphate rock equivalent could be easily obtained from the incineration ash of chicken manure, which means that approximately 14% of the phosphate rock that is currently being imported into Japan could be replaced by this product.


Gas Phase Epoxidation of Propylene to Propylene Oxide on a Supported Catalyst Modified with Various Dopants

In the present study, the production of propylene oxide (PO) from propylene via gas phase epoxidation was investigated using various catalysts. Although Ag is known to be a highly active catalyst for the epoxidation of ethylene, it was not active in the present reaction. Both Al and/or Ti showed high level of activity, however, which resulted in confusion. The present study was conducted to solve such confusion. The intent of the present study was to solve such confusion. Although the employment of MCM 41 modified with Ti and/or Al was reported as an active catalyst for epoxidation, the combination resulted in a formation of PO that amounted to less than a 0.1% yield. Since this research revealed that the acidic catalyst seemed favorable for the formation of PO, versions of ZSM 5 that were both undoped and doped with Na, Ti and Ag were used as catalysts. In these cases, small improvements of 0.67 and 0.57% were achieved in the PO yield on H ZSM 5 and Ti ZSM 5. Based on the results of the Ti dopant and acidic catalysts, Ag metal doped on carbonate species with a smaller surface area was used as a catalyst. As reported, Ag Na/CaCO3 showed a greater yield of PO at 1.29%. Furthermore, the use of SrCO3 for CaCO3 resulted in a further improvement in the PO yield to 2.17%. An experiment using CO2 and NH3 pulse together with SEM and TEM examinations for Ag Na/CaCO3 revealed that the greatest amount of activity was the result of the greater particle size of metallic Ag rather than the acid base properties of the catalysts.


Modifying SBA-15 with Binary Elements of Chromium and Molybdenum for Improved Catalytic Performance in the Oxidative Dehydrogenation of Isobutane to Isobutene

In the oxidative dehydrogenation of isobutane to isobutene, selectivity and stability were improved by introducing chromium and molybdenum into SBA-15. The direct synthesis method (DM) was used to introduce these binary elements into SBA-15. Use of the DM resulted in a higher specific surface area of the catalyst and a greater dispersion of chromium and molybdenum species compared with a corresponding binary catalyst prepared using the incipient wetness impregnation method (IM). Selectivity to isobutene was improved, along with a decrease in the selectivities to CO and CO2 with the introduction of greater amounts of molybdenum, which suggests that molybdenum must suppress the tendency of isobutene to over-oxidate to either CO or CO2. The molybdenum species must be in close proximity to the chromium species, which results in the formation of an active Cr-O-Mo site.

Journal of Chemical Engineering of Japan


Enhancement of water adsorption-desorption performance of aluminophosphate molecular sieves (AlPO-5) substituted with several metals

Aluminophosphate molecular sieves (AlPO-5) were substituted with seven metals (Ca, Co, Mg, Ni, Sr, Cr and Fe). From XRD measurement, all patterns of seven substituted AlPO-5 were identical to that of the AFI structure. Except for Cr substituted for AlPO-5, they were mainly in a hexagonal pillar structure from SEM images. For Mg, Ni, Sr and Fe substituted for AlPO-5, the water adsorption capacity at 30 and the difference in the amount of adsorbed water between 30 (adsorption temperature) and 100 (desorption temperature) increased by the substitution. Although, for Fe substituted AlPO-5, the initial water adsorption rate was slightly decreased by the substitution, the water desorption temperature was equal for the temperature of AlPO-5. Because Fe substituted for AlPO-5 had about 1.8 times of water adsorption capacity at 30 and were able to be regenerated at 100, Fe substituted for AlPO-5 was most advantageous adsorbents.


Effect of Introduction of Trace Amount of Chromium Species in Improving Catalytic Performance of MCM-48 in Oxidative Dehydrogenation of Isobutane

The catalytic performance of MCM-48 was greatly improved by the introduction of a small amount of chromium during the oxidative dehydrogenation of isobutane. Various characterization procedures such as XRD, N2 adsorption-desorption isotherms, TEM, NH3-TPD, XPS, and XAFS were used to clarify the role that chromium played in the improvement, and XPS and XAFS returned the most valuable information. Both measurements revealed that the chromium species existed as Cr6+ inside the framework of MCM-48 before oxidative dehydrogenation, but was reduced to Cr3+ during the reaction. The characteristic pore nature of MCM-48 also contributed to an enhancement of the selectivity to isobutene via a suppression of any consecutive oxidation reactions.


Application of Si/SiC Ceramic Filters as Support for Structural Palladium Catalysts for the Reductive Decomposition of Aqueous Nitrite

A Si/SiC ceramic filter was used to support a structural palladium catalyst in a continuous fixed-bed flow reactor during a reductive decomposition of nitrite. A previous report described the use of non-porous alumina spheres coated with Pd/C, a carbon monolith impregnated with Pd or a structural catalyst consisting of a polyurethane sponge skeleton impregnated with Pd resulted either in negligible activity or a complete stoppage of the flow by increasing the pressure drop in the flow system. The use of a Si/SiC filter impregnated with palladium, however, overcame the demerits and resulted in an 11% conversion of nitrite in 60 min. The use of a Si/SiC filter coated with a char intermediate followed by impregnation with Pd (Pd/C/Si/SiC) resulted in a structural catalyst that enhanced the activity to yield a 33% conversion of nitrite in 60 min. When five Pd/C/Si/SiC structural catalysts were used, however, the complete decomposition was achieved in the same amount of time. Although improvement was previously observed by using an alumina intermediate, use of the char intermediate resulted in a new factor for activity improvement. The characterization results show that it was the affinity between aqueous nitrite and the intermediate rather than palladium dispersion that contributed the most to the improvement of activity.


Enhancement in Boiling Heat Transfer for Water Using a Polished Plate Surface

The thermal characteristic of a plate evaporator for boiling water have been experimentally investigated. Stainless-steel plates with five kinds of surface roughness (a mirror-polished surface and four kinds of polished plate surface, F2, F0, F-1, and F-2 polishing) were used for the investigation. The roughness order is F-2>F-1>F0>F2>mirror. The local boiling heat transfers were measured on the evaporator surface using ten thermocouples inside the evaporator. For a comparison of the heat transfer characteristic of the evaporator, the local boiling heat transfer coefficient was measured when the polishing direction was perpendicular or parallel to the water flow at a range of pressures (0.30.4MPa) and flow rates (2060mL/min). The results indicate that the local heat transfer coefficient increased with increasing vapor quality at all surface conditions. For F0 polishing, the heat transfer coefficient on the surface with perpendicular polishing was much larger than that on the surfaces with parallel and mirror polishing. In particular, the heat transfer coefficient of the perpendicularly polished surface (F2 and F0 polishing) was increased six-fold in comparison with that of the mirror surface at a vapor quality of 0.35. However, for the F-1 and F-2 perpendicularly polishing plates, the heat transfer coefficients were smaller than those of the F0 and F2 perpendicularly polishing plates. For the F2 perpendicularly polished plate, heat transfer enhancement was confirmed, along with an increase in the number of bubbling points, on increasing the system pressure. For the polished surface, the heat transfer coefficient increased with increasing flow rate. This indicates that the bubble formation cycle was promoted by an increased flow rate.


Introduction of a Small Amount of Chromium to Enhance the Catalytic Performance of SBA-15 for the Oxidative Dehydrogenation of Isobutane to Isobutene

Various solid oxide catalysts are active in the oxidative dehydrogenation of propane, but when these were used for the oxidative dehydrogenation of isobutane to isobutene, the yield was less than 2%. An improved yield of isobutene to 8% was obtained in the oxidative dehydrogenation of isobutane using folded-sheet mesoporous material (FSM-16) and mesoporous molecular sieve (MCM-41), either added or unadded with chromium via impregnation or template ion exchange methods. Further activity enhancement, however, could not be attained. In the present study, in order to introduce chromium cations into the framework of SBA-15 using a direct synthesis method, chromium nitrate was mixed with TEOS in an aqueous starting solution with pH adjusted to 1.5, which was followed by the hydrothermal treatment. Loading the resultant catalyst, SBA-15, with a small amount of chromium (1.84 wt% Cr-SBA-15) returned a greater yield of isobutene (15.4%) at 723 K, although previous report showed that SBA-15 supported with chromium oxide (CrOx/SBA-15) prepared via incipient wetness impregnation showed a lower yield of isobutene (11%) at 813 K. In order to explain such an improvement, the catalysts were characterized using XRD, TEM, N2 adsorption-desorption and NH3 temperature-programmed desorption. A substantial amount of specific surface area (1,610 m2/g) was detected in active Cr-SBA-15, although the structural and acidic nature of the catalyst showed the general properties of other mesoporous silicas. It is possible that when the Cr6+ species is converted from Cr3+, the great specific surface area of Cr-SBA-15 could be a factor in the oxidative dehydrogenation of isobutane to isobutene.


Reductive Decomposition of Nitrite in a Continuous-Flow Reactor Using Fixed-Bed Structural Pd Catalysts

In order to decompose trace amounts of nitrite in drinking water under mild conditions, a fixed-bed filtering system that used structural catalysts was employed to filter recycled aqueous nitrite. High performance and continuous mass processing are generally accepted as requirements to catalyze the decomposition of aqueous nitrite. However, the use of a fixed-bed operation when recycling aqueous nitrite with palladium catalyst systems could result in either negligible activity when using a carbon monolith impregnated with Pd, or could stop the flow by enhancing the pressure drop when using non-porous alumina spheres coated with Pd/C or structural catalysts consisting of a polyurethane sponge skeleton impregnated with Pd. In the present paper, a Si/SiC ceramic filter was employed as a structural support to prevent pressure drop. When palladium was loaded onto the surface of the filter via electroless plating, continuous flow suitably continued, and the conversion of nitrite was 45% after 60 min. In contrast, when palladium was loaded after the coating of the filter with alumina, complete decomposition was achieved after 60 min under conditions corresponding to those used for the former system. X-ray diffraction, an N2 adsorption-desorption measurement, scanning-electron microscopy, and energy-dispersive X-ray spectroscopy analyses revealed that a higher dispersion of palladium on the latter structural catalyst resulted in the greatest level of activity for the reductive decomposition of aqueous nitrite.


Catalyst Deactivation of a Silica-supported Bismuth-molybdenum Complex Oxide and the Related Complex Oxides for the Oxidative Dehydrogenation of 1-Butene to 1,3-Butadiene

This study was an examination of the catalyst deactivation of a silica-supported bismuth-molybdenum complex oxide, and that of catalysts used in the absence of bismuth, for the oxidative dehydrogenation of 1-butene. Due to the detection of deactivation, the molar ratio of 1-butene against oxygen in the reactant gas was adjusted to a ratio similar to that used in industrial processes where reaction temperatures average 100 K higher. Regardless of the presence or absence of bismuth in the catalysts, the conversion of 1-butene was decreased by 6 h on-stream. Both the progress of the coking from the inlet to the outlet of the catalyst and the reduction of molybdenum in the catalysts directly contributed to the deactivation. X-ray photoelectron spectrometry revealed that a greater reduction of molybdenum in the near-surface region and a smaller partial pressure of oxygen (P(O2)) in the reactant gas, although the molybdenum on the surface was not reduced at all. This indicated that the lattice oxygen was pumped from the near-surface region to the surface during the reaction and the oxygen-poor conditions of the near-surface region both in the gas and catalyst phases were formed at a smaller P(O2), which resulted in the enhancements of both the reduction of molybdenum and that of coking. Based on the thermogravimetric analysis, the silica-supported bismuth-molybdenum complex oxide used at P(O2) = 4.1 kPa (color of the catalyst = black) was increased in weight while that used at P(O2) = 16.4 kPa (color of the catalyst = gray) showed a weight decrease, which indicated that the weight decrease caused by the reduction in molybdenum in the near-surface region used at 4.1 kPa was greater than the weight increase from the coking. It was concluded that the reduction in molybdenum followed by the coking on the catalyst surface were the main factors in the catalyst deactivation.


Effects of Acidic-basic Properties on Catalytic Activity for the Oxidative Dehydrogenation of Isobutane on Calcium Phosphates, Doped and Undoped with Chromium

The catalytic activities of calcium hydroxyapatite (HAp) and β-type tricalcium phosphate (β-TCP) were examined for their use in the oxidative dehydrogenation (ODH) of isobutane. β-TCP was catalytically inactive for the ODH of isobutane, but stoichiometric HAp returned a high isobutene yield (5.6%). The isobutane conversion and isobutene selectivity of HAp depended on the atomic ratio of Ca/P. HAp with a Ca/P = 1.67 showed the highest levels for both isobutene selectivity and isobutene yield from among HAp catalysts with different Ca/P ratios. Based on a characterization of the acidic-basic properties, it was evident that these acidic-basic properties affect the catalytic performance of HAp, and that its basicity is necessary for high catalytic activity. To improve the catalytic activities of calcium phosphates, they were impregnated with Cr. Despite a much lower surface area for β-TCP, Cr-impregnated β-TCP showed a higher isobutene yield (up to 8.4%) than that of Cr-impregnated HAp. The results of the XPS measurement showed that the Cr3+ species on calcium phosphates, together with the basicity, worked as active sites in the ODH of isobutane.

Journal of Chemical Engineering of Japan


High Thermal Stability Ceria Synthesized via Thermal Hydrolysis Route and Methane Combustion Performance

Enhancement of the thermal stability of a catalyst is an efficient way to improve the catalytic activity of a catalytic reaction performed at high temperature. In this study, cerium oxide (ceria, CeO¬2) with a high thermal stability was synthesized by controlling the agglomeration of the primary particles via the thermal hydrolysis of ceric nitrate, accompanied by testing for the catalytic combustion of methane (CH4). The specific surface area of this material after calcination at 1,173 K for 5 h was 50 m2/g, which was much higher than that of the two references materials (ceria made via precipitation of cerous nitrate using aqueous ammonia at 4.1 m2/g, and the Japan reference catalyst JRC-CEO-1 at 1.4 m2/g). The ceria made via thermal hydrolysis showed high crystallinity and a much higher pore volume, which resulted in excellent thermal resistance. For O2 conversion in ceria, catalyzed CH4 combustion at 923 K, the ceria created in this study demonstrated higher activity than that for either reference. The high CH4 combustion performance was due to the high specific surface area and to a superior oxygen storage capacity (OSC) even after a combustion test.

高温安定性をもつセリアを合成できることを纏めた論文．今回合成したセリアは1173Kで5時間焼成しても50 m2/gの比表面積を持つが，通常の参照触媒は1.4 m2/g，沈積法で調製した場合でも4.1 m2/gしかなく，今回報告したセリアの熱安定性は従来にはないものである．メタン燃焼に高温安定セリアを用いた場合，比較的低温度では，比表面積に相当する活性を与える一方，高温領域では触媒表面への吸着-脱離が律速段階からはずれすために，比表面積によらずほぼ一定の活性を示した．


Formation of Cerium Carbonate Hydroxide and Cerium Oxide Nanostructures by Self-Assembly of Nanoparticles Using Surfactant Template and Their Catalytic Oxidation


Hydrothermally Synthesized Ceria with a High Specific Surface Area for Catalytic Conversion of Ethanol to Ethylene

Morphological control can be used to improve the catalytic activity of cerium oxide (ceria, CeO2). For this study, ceria with a high specific surface area was synthesized via the hydrothermal reac-tion of ceric nitrate and was tested on the catalytic conversion of ethanol to ethylene. For a refer-ence, ceria was also synthesized via a precipitation reaction of cerous nitrate using aqueous am-monia. The Japan reference catalyst, JRC-CEO-1 also served as a reference. The specific surface area of the hydrothermally synthesized ceria was as high as that of JRC-CEO-1, but was much higher than that of either of the references after calcination at 873 K. Thermo-gravimetric analysis and IR spectroscopy revealed that the cerias made by hydrothermal and precipitation reactions consisted of high-purity CeO2, while the JRC-CEO-1 contained 1.5% decomposable functional groups (OH-, CO32-). For both ethanol conversion and ethylene selectivity in a catalytic dehydration reaction of ethanol, the activity of the hydrothermally developed ceria was higher than that for either of the references. The reaction pathway for the dehydration reaction of ethanol over ceria showed that the specific surface area and the basicity of the Lewis basic site of the ceria were specific influential properties. The high catalytic activity of the hydrothermally synthesized ceria derived from its high specific surface area and high-purity CeO2.

本研究で提案した調製法で合成した酸化セリウムは，シンタリング耐性が高いことが知られていたが，エタノールからエチレンへの接触反応の触媒として高活性を示し，今回の調製法で調製すると高表面積を持つ純度の高い酸化セリウムができることが原因であることを明らかにした．


Effects of Acid Treatment on the Acidic Properties and Catalytic Activity of MCM-41 for the Oxidative Dehydrogenation of Isobutane

Mesoporous silicas have shown promise as materials for solid catalysts or catalyst supports due to their unique characteristics. Metal-doped mesoporous silicas are known to be catalytically active in the oxidative dehydrogenation (ODH) of isobutane. However, heavy-metal-free mesoporous silicas have not been studied closely for their use as catalysts. In the present study, MCM-41 (#41 Mobil composition of matter) was acid-treated to enhance its catalytic activity, although pure MCM-41 was confirmed as catalytically inactive for the ODH of isobutane (isobutene yield = 0.9%). The pH of a slurry of as-synthesized MCM-41 was changed during acid treatment. A pH adjustment to 6.5 resulted in great improvement in catalytic activity (isobutene yield = 6.1%), but a pH adjustment to 4.5 resulted in insufficient improvement (isobutene yield = 4.5%). It was confirmed via XRD and N2 adsorption-desorption measurement that the pH adjustment to 4.5 degraded the ordered structure of MCM-41. This degradation would be a crucial factor that would render acid treatment less effective. In addition to the acid treatment, Al doping to MCM-41 was conducted. Al doping also greatly enhanced the acidity and catalytic activity of MCM-41.

酸で処理またアルミニウムで修飾したMCM-41が，イソブタンの接触酸化脱水素反応によるイソブテンへの触媒として高活性であることを明らかにした．従来は重金属による修飾が必須修であった本触媒系において，重金属を用いない環境に配慮した触媒を調製できることを明らかにした．


Recovery of Calcium Phosphates from Composted Chicken Manure

To recover phosphorus from composted chicken manure, a batch method with aqueous HNO3, HCl and H2SO4 was used to examine the elution behavior of the aqueous calcium and phosphate contained in the manure. Since the main components in manure are Ca2+ and K+ along with PO43- and those ions can be dissolved using an acidic eluate, it was expected that most of the aqueous Ca2+, K+ and PO43- could be obtained via the elution. Therefore, it seemed plausible that the removal of the aqueous K+ obtained by the elution of composted chicken manure would result in the formation of calcium phosphates. If calcium phosphates are formed, they can be used for phosphate rock, which also consists of various calcium phosphates. When using 0.1 mol/L HNO3, HCl or H2SO4, the elution behavior of the PO43- was not dependent on the acids. However, 0.1 mol/L H2SO4 was not sufficient for the elution of Ca2+, probably due to the precipitation of the calcium sulfate. The eluted amount of K+ using 0.1 mol/L HNO3 was lower than that using 0.1 mol/L of either HCl or H2SO4. Since the poor elution of K+ should enrich the concentrations of Ca2+ and PO43- in the acidic aqueous solution after the elution, it was suggested that aqueous HNO3 would be suitable as an eluate in the present system. After the elution of the composted chicken manure, when 0.1 mol/L HNO3 was used to adjust the solution pH of the acidic aqueous solution to greater than 6, Ca2+ and PO43- were precipitated, but K+ was not. The precipitation was calcium hydroxyapatite, one of the typical components of phosphate rock, which showed that composted chicken manure could be replaced phosphate rock as a new source of phosphorus.

コンポスト化鶏糞を硝酸水溶液による湿式処理を行い，得られた水溶液をアンモニアでpHを制御すると，リン鉱石の主成分であるリン酸カルシウムを高純度で得ることができ，枯渇資源リンを廃棄物鶏糞から効率よく取得できることが明らかになった．


Oxidative Dehydrogenation of Isobutane to Isobutene on Metal-doped MCM-41 Catalysts

MCM-41 (#41 Mobil Composition of Matter) is a favorable material for heterogeneous reactions because of its unique porous structure. However, the catalytic activity of MCM-41 for the oxidative dehydrogenation (ODH) of isobutane to isobutene is known to be quite low. In the present study, a metal-doping method was employed to improve this catalytic activity. Doping of Cr, Co, Ni, or Mo into MCM-41 resulted in a great improvement in the catalytic activity. Since chromium-doped MCM-41 (Cr-MCM-41) showed the greatest catalytic activity among these catalysts, its redox property was further analyzed via XPS, XAFS and H2-TPR techniques. The XPS spectrum of Cr-MCM-41 suggested that it has Cr3+ and Cr6+ species on its surface. Also, a pre-edge peak due to Cr6+ species was confirmed in the XANES spectrum of Cr-MCM-41. In H2-TPR measurement, Cr-MCM-41 was more reducible than crystalline Cr2O3, which showed low catalytic activity for the ODH of isobutane. The reducible Cr6+ species on Cr-MCM-41 contributed to an improvement in the catalytic activity of MCM-41.

Crで修飾したMCM-41が，イソブタンの接触酸化脱水素反応によるイソブテンへの触媒として高活性であることを明らかにした．種々より還元性の高い6価のCrが活性改善に寄与していることが明らかになった．


The effects of created mesopores in ZSM-5 zeolites by an alkali treatment on water adsorption

Three kinds of ZSM-5 zeolites (SiO2/Al2O3=23.8 (Na-form), 39.0 (NH4-form) and 193(NH4-form)) were alkali-treated, and the changes in structural and water adsorptive properties were investigated. With the alkali treatment, the MFI structure was kept; a siliceous species was selectively dissolved from the framework of a zeolite, and the mesopores were created in the zeolites. At the same time, NH4-form ZSM-5 zeolites (SiO2/Al2O3=39.0 and 193) were ion-exchanged to form Na in an aqueous solution of NaOH. In particular, for ZSM-5 (SiO2/Al2O3=23.8), the water adsorption property was changed with the alkali treatment. The difference in the amount of adsorbed water on the zeolite between 30℃ (adsorption temperature) and 100℃(desorption temperature) was increased by the treatment. The desorption temperature of water adsorbed at the stronger site was decreased from 106℃ to 72℃ with the alkali treatment. These results indicate that the introduction of mesopores in ZSM-5 contributed to the enhanced water adsorption properties.


Effect of the Template Ion Exchange Behaviors of Chromium into FSM-16 on the Oxidative Dehydrogenation of Isobutane

The template ion exchange of chromium cations into FSM-16 (#16 Folded Sheets Mesoporous Materials) for 247 h resulted in a 2.89 wt% incorporation of those cations into the FSM-16, although only a 0.3 wt% incorporation had previously been reported. The XRD pattern of the resultant solid (Cr-FSM-16) showed that the hexagonal structure characteristic of FSM-16 remained after the 2.89 wt% incorporation of chromium cations. XPS could be used to detect the Cr3+ and Cr6+ species on the surface of Cr-FSM-16. A pre-edge peak that was due to a tetrahedrally coordinated Cr6+ species was confirmed in the XANES spectrum of the Cr-FSM-16, which showed that the coordination state around some Cr species was similar to that around the Si species in FSM-16. With the increase in the amount of chromium cations in FSM-16, its catalytic activity and stability during the oxidative dehydrogenation of isobutane were evidently improved.

クロムカチオンのメソポラスシリカであるFSM-16へのテンプレートイオン交換挙動はが検討され，従来は0.3wt%までしかクロムをイオン交換できなかったが，247時間のイオン交換の結果2.89%まで導入できた．XRD分析よりクロムを導入しても構造は変化しなかったが，クロムは3価と6価のカチオンが検出され，特に6価のクロムはヘキサゴナル構造を取って取り込まれることがXAFSで確認された．このクロム導入FSM-16はイソブタンの酸化脱水素反応の触媒として高活性を示した．


Modification of commercial NaY zeolite to give high water diffusivity and adsorb a large amount of water

By using NaY zeolites as desiccant materials, commercial NaY zeolite was alkali treated with 1M NaOH aqueous solution and then Mg2+ ion-exchanged by 0.5M Mg(NO3)2 aqueous solution. Alkali treatment (AT) of NaY zeolite removed silicon atoms selectivity from the framework of Y-type zeolite and enhanced water diffusivity of Y-type zeolite. On the other hand, Mg2+ ion-exchange of NaY zeolite increased the amount of water adsorbed. Prepared Y-AT-Mg zeolite had both water adsorption velocity and a large difference of water adsorbed amount between adsorption at 30℃ and desorption at 100℃.

Journal of Colloid and Interface Science


Morphological effects of CeO2 nanostructures for catalytic soot combustion of CuO/CeO2


Influence of alkali concentration on morphology and tensile properties of abaca fibers


Effects of the Acidic Properties of FSM-16 on the Catalytic Conversion of 1,2-Propandiol in the Presence and Absence of Hydrogen

In our previous paper, we showed how the catalytic conversion of 1,2-propandiol to propanal using FSM-16 (#16 Folded Sheets of Mesoporous materials) when molded by wet treatment proceeded more favorably than when using FSM-16 molded by pressurization, while no comparison using other typical acidic catalysts and no examination of the acidic properties of FSM-16 was carried out. In the present study, the conversion using FSM-16 molded by wet-treatment and pressurization was compared with the use of typical acidic catalysts such as SiW12O40/SiO2 and MCM-41 (#41 of Mobil Composition of Matter) together with amorphous SiO2. Among these catalysts, FSM-16 molded by wet treatment showed the most suitable catalytic activity. In order to examine the effect of the molding procedure for FSM-16 on its structural and acidic properties, FSM-16 molded by both methods was examined using NH3-TPD, in-situ FT-IR using NH3 as a probe molecule and Hammett indicators together with XRD and TEM. According to Zaitsev's rule, the present conversion should afford acetone rather than propanal, which indicates that it would proceed via hydro-cracking. Therefore the conversion of 1,2-propandiol using FSM-16 was also examined in the presence and absence of hydrogen. Furthermore the hydrations of 1- and 2-propanol when using FMS-16 were also examined. Based on the results obtained from this investigation, it was concluded that the conversion using a more acidic FSM-16 molded by wet treatment proceeded through dehydration rather than through hydro-cracking.

我々は，FSM-16が1,2-プロパンジオールからプロパナールへの高活性触媒であることを見出した．本論文では，高活性の発現因子を解明するため，構造解析と酸性質の詳細な検討を行い，ヘキサゴナル構造を保持した，酸性質の高い触媒が活性を与えることを示した．さらに，反応機構が水素化分解機構か，脱水素機構化という点を原料ガスに水素を添加して検討し，脱水機構で進むことを明らかにした．

Journal of Chemical Engineering of Japan


Influence of alkali treatment on internal microstructure and tensile properties of abaca fibers

The objective of this study is to investigate the effect of alkali treatment on the internal microstructure and tensile properties of abaca fibers. The abaca fibers were immersed in aqueous solutions of NaOH (5, 10, or 15 wt%) for 30 min, rinsed and dried. The fibers were subsequently characterized by scanning electron microscopy, X-ray diffraction (XRD), Fourier transform-infrared spectroscopy (FT-IR), and tensile strength tests. The lumen is a hollow region in each elementary fiber of the abaca fiber bundles. It was found that the lumen of the abaca fibers completely collapsed after 10 and 15 wt% NaOH treatment, due to swelling of the fibers. The fibers also became twisted after these alkali treatments. It was found that cellulose I in abaca fibers was partially transformed to cellulose II after 15 wt% NaOH treatment, as evidenced by XRD measurements. FT-IR analysis indicated that the alkali treatment led to a gradual removal of binding materials; such as hemicelluloses and lignin, from the abaca fibers, resulting in the separation of abaca fiber bundles into individual elementary fibers. The tensile strength of alkali-treated abaca fibers did not vary with alkali concentration. The Young's modulus of the abaca fibers treated with 5 wt% NaOH solution increased by 41%, whereas those treated with 10 and 15 wt% NaOH solution decreased by 24 and 29%, respectively. A non-linear behavior was observed in the stress strain curves of the abaca fibers after 10 and 15 wt% alkali treatment, which could be attributable to the twisting of the fibers.

アバカ繊維の内部構造と引張特性に及ぼすアルカリ処理の影響について調査した．繊維中のルーメンは10,15wt%NaOHで処理すると消失すると共に繊維がツイストすることを見いだした．アルカリ処理したアバカ繊維の引張強度にはほとんど変化はない．しかし，5wt%NaOHで処理した場合，ヤング率は41%増加するのに対して，10,15wt%NaOHで処理するとそれぞれ24%，29%低下する．10,15wt%NaOHで処理したアバカ繊維は非線形の応力-ひずみ関係になり，この非線形性は繊維のツイスト化によってもたらされると推察される．


Recovery of the Phosphorus from the Nitric Acid Extract of Powder Collected in a Bag Filter during the Recycling of Used Fluorescence Tubes

rescence tubes (bag-powder), the batch method with aqueous HNO3 was used to examine the elution behavior of aqueous phosphate contained in the bag-powder. The main components of the bag-powder included Ca2+, PO43- and Y3+ along with Si4+, Sr2+ and lanthanide cations such as La3+ and Ce4+. Therefore, it seemed possible that, with the selective dissolution of Ca2+ and PO43- from the bag-powder, those lanthanide cations in the residue could be enriched. With the batch method, most of the phosphate in the bag-powder was dissolved within 0.2 min using 1.0 mol/L HNO3. The dissolution behavior of calcium cation was similar to that of the phosphate. In contrast, the dissolution of yttrium, the content of which was the highest among the lanthanide cations in the bag-powder, was increased with the dissolution times, reaching complete dissolution after 24 h. The Sr2+, La3+ and Si4+ in the bag-powder, however, did not dissolve under the same conditions. Although Ca2+, PO43- and Y3+ were the main components in the nitric acid extract, Y3+ was separated as YPO4 at pH = 4.0, while Ca2+ and PO43- were separated as calcium phosphates at pH= 7.0. These results revealed that the separation of calcium phosphates, YPO4 and some residue was possible, and resulted in the enrichment of lanthanide cations along with the recovery of phosphorus from the bag-powder. Using the present technique, 91% of the P in the bag-powder was recovered.

回収蛍光管処理後のバグフィルター回収粉末には，Ca2+, PO43-，Y3+，Si4+, Sr2+，La3+ やCe4+などが含まれている．この粉末を酸性溶媒で溶出処理を行い，アンモニア水により，pH=4.0にして，Y3+を回収し，さらにpH=7.0とすることにより，高純度のリン酸カルシウムを回収することができた．特にリンは91%回収することができ，枯渇資源リンとレアアースのY3+を安価で，容易に分離濃縮できることを明らかにした


Acidic Properties of Various Silica Catalysts Doped with Chromium for the Oxidative Dehydrogenation of Isobutane to Isobutene

Although previous researchers have found that FSM-16 (#16 Folded Sheet Mesoporous material) doped with chromium and related Cr-doped silica catalysts has shown great activity for the oxidative dehydrogenation of isobutane to isobutene, information on the nature of these catalysts is insufficient. For this study, three types of Cr-doped silica catalysts were prepared by applying the template ion exchange method. CrOx/FSM-16 and CrOx/SiO2 were used as references. These catalysts were used for oxidative dehydrogenation, which was then characterized via various techniques. The most active catalyst was Cr-doped silica, which did not have the hexagonal structure that is characteristic of mesoporous FSM-16. Various characterizations showed that the catalytic activity of the Cr-species, stemmed from a weak acidic nature and a redox nature that originated from the combination of silicate and a Cr cation, as opposed to the hexagonal structure and strong acidic nature of FSM-16.

前報でCrで修飾したFSM-16がイソブタンの接触酸化脱水素反応によるイソブテンに対して優れた活性を示すことを示した．本論文では，活性の発現因子を明らかにするために，基準となるCrOx/FSM-16やCrOx/SiO2触媒とともに，活性試験，構造解析，酸性質の詳細な検討を行った．その結果，FSM-16のメソ構造を破壊し，中程度の酸強度，酸量を持つCrで修飾したFSM-16が高活性を示すことを明らかにした．特に，Crのレドックス挙動とFSM-16の酸性質の相乗作用で活性が発現していることが確認された．


Enhanced Photocatalytic Hydrogen Evolution from Water by Niobate Single Molecular Sheets and Ensembles

We report single molecular sheets of niobate prepared by a simple bottom-up approach using hydrothermal synthesis of niobium ethoxide with the aid of triethanolamine as a structural modifier: the high kinetic stability of these molecular entities against self-assembly allows them to mix well with other colloids and facilitates their extensive electronic interactions and thus photocatalytic hydrogen evolution activity from water is much enhanced over composite of single niobate sheets with graphene and MoS2 due to efficient electron transfer and charge separation.


Recovery and Enrichment of Phosphorus from the Nitric Acid Extract of Dephosphorization Slag

A method for the recovery and enrichment of the phosphate from dephosphorization slag was examined. First, the elution of aqueous phosphate from dephosphorization slag using aqueous HNO3 was examined using both the batch and flow methods. With the batch method, 82% of the dephosphorization slag could be dissolved within 30 min using 1.0 mol/L HNO3, indicating that the batch method could be used for mass processing to extract phosphorus in the bulk phase, but all components contained in the slag were unselectively dissolved. In contrast, by using 0.05 mol/L HNO3 via the flow method, 22% of the slag was dissolved for 100 min giving a more selective dissolution of phosphate from the slag compared with the batch method, which indicated that this method would be incompatible with mass processing for the purpose of extracting phosphorus in the bulk phase. In order to remove the Fe-species in the aqueous solution obtained by the batch method using 1.0 mol/L HNO3, which has been referred to as the ``slag solution,'' it was necessary to add calcium hydroxyapatite (CaHAp) to the slag solution. The optimal conditions for the removal of Fe-species using CaHAp were observed at a solution pH of ca. 1.5, which resulted in 100% removal of the Fe-species after 4 h. When the pH of the slag solution was adjusted to 7.0 after removing the Fe species, a pale pink solid sample was precipitated. The amounts of phosphate in the slag solution and in the pink solid were 3.5 and 42.0 mol%, respectively, indicating that the treatment suggested in the present study could be used for the recovery and enrichment of phosphate, that is, phosphorous, from dephosphorization slag.

脱リンスラグからのリンの回収と濃縮について検討した．回分式反応器を用いて脱リンスラグを1.0 mol/L HNO3で処理を行うと82%溶解できたが，リンを選択的に溶出できなかった．そこで0.05 mil/L HNO3で処理すると22%しか溶解できなかったが，リンを比較的選択的に溶出できた．溶解後に共存する鉄をカルシウム水酸アパタイトで除去し，溶液のpHを7.0にすることにより42%のリンを含むリン化合物を溶出させることができた．


Effect of Reaction Temperature and Steam to Carbon Ratio on Hydrogen Production for Steam Reforming of Bio-Ethanol Using the Palladium Membrane Reactor

The steam reforming of bio-ethanol has been carried out to compare with reagent ethanol using a palladium membrane at several reaction conditions (673 or 873 K, ΔP=0.10 MPa and steam-to-carbon ratio (S/C)=4-10). The raw material of these experiments was surplus bio-ethanol, which is one of the by-products in fermentation with sulfuring process in cornstarch production. As a result, the amount of total H2 formation for bio-ethanol was comparable to that obtained with reagent ethanol under the same conditions. However, for bio-ethanol, the values of hydrogen permeate flow and hydrogen purity were smaller than that of reagent ethanol. In contrast, the amount of CO formed from bio-ethanol was greater than that from reagent ethanol. It is considered that carbon, which has a negative influence on the hydrogen-permeability of the palladium membrane, was produced from CO. The amount of CO was significantly decreased by lowering the temperature from 873 to 673 K. Moreover, CO was also decreased by increasing S/C and was not detected over S/C of 8. However, the amount of total hydrogen production and hydrogen permeate flow decreased by increasing the S/C ratio. Therefore, the best condition for hydrogen production from bio-ethanol using the palladium membrane reactor was at 673 K and S/C=8.


Oxidative Dehydrogenation of Isobutane to Isobutene on FSM-16 Doped with Cr and Related Catalysts

The oxidative dehydrogenation of isobutane to isobutene was examined for use in the preparation of FSM-16 and related compounds doped by chromium with expectations that a yield of isobutene of greater than 8% could be achieved. The activity depended on the molding procedure of the catalyst and the doping method of the chromium species. In the present study, 8.8 and 8.3% of the yield of isobutene were obtained at 0.75 and 6 h on-stream for the catalyst (Cr-loading; 6.2 wt.%) molded using wet treatment but not pressurization treatment, in which the chromium species were directly added into the aqueous solution containing raw FSM-16 (hydrated sodium silicate powder) at an initial stage of the catalyst preparation. The structure information was based on XRD, the specific surface area was determined using a conventional BET nitrogen adsorption and the loading of chromium was estimated using ICP. All those parameters combined with the molding method indicated that the catalytic activity was more influenced by the loading of chromium into bulk but not on surface of the catalyst rather than by the hexagonal structure of FSM-16 and the surface area.

クロムで修飾したFSM-16および関連触媒によるイソブタンからイソブテンへの酸化脱水素が検討された．FSM-16の調製段階時にクロムを導入し，湿式成型した触媒を用いたところ，通塔45分および4.5時間後に8.8および8.3%の目的を超えるイソブテン収率を得た．高収率は，FSM-16のヘキサゴナル構造や高比表面積ではなくバルク層に導入されたクロム導入量に依存することが明らかになった．

Journal of Chemistry and Chemical Engineering


The Catalytic Conversion of 1,2-Propandiol to Propanal on FSM-16 Molded by Wet-Treatment and Pressurization

The catalytic conversion of 1,2-propandiol to propanal is examined using FSM-16 particles (0.85-1.75 mm) molded by wet-treatment and pressurization. When FSM-16 was molded with 0.6 g of pressurization and supplied to the catalytic conversion of 1,2-propandiol at 673 K, this system resulted in a 94.8% conversion of 1,2-propandiol and 90.5% selectivity to propanal at 0.25 h on-stream, which was the maximum amount of activity. However, at 4.50 h on-stream, the activity was decreased extremely to deactivation 19.9% conversion of 1,2-propandiol and 84.7% selectivity to propanal. In contrast, when FSM-16 molded with wettreatment (0.15 g) was used for the conversion at 573 K, activity was greatly increased and stable 98.6% conversion of 1,2-propandiol and 56.2% selectivity to propanal at 0.25 h on-stream followed by 91.9% and 52.5%, respectively, at 4.50 h on-stream. The hexagonal structure of FSM-16 was suggested to have contributed to the suitable conversion of 1,2-propandiol to propanal.

1,2-プロパンジオールからプロパナールへの接触変換を加圧成型したFSM-16(粒径0.85-1.75 mm)を0.6g用い673Kで行うと，通塔15分後には94.8%の変化率でプロパナールを90.5%の選択率で合成できたが，著しい活性劣化を示し，通塔4.5時間後には，変化率19.9%，選択率84.7%となった．一方湿式成型したFSM-16を0.15g用い反応を行うと，変化率98.6%選択率56.2%が通塔15分後に検出され，通塔4.5時間後まで維持された(それぞれ91.9,52.5%)．FSM-16中のヘキサゴナルな構造が維持されると安定した触媒活性が得られることが明らかになった．

Journal of Chemical Engineering of Japan


The Oxidative Esterification of Propionaldehyde to Methyl Propionate in the Liquid-phase Using a Heterogeneous Palladium Catalyst

The optimization of the oxidative esterification of propionaldehyde to methyl propionate using a supported palladium catalyst in methanol under heavy-metal-free and pressurized-oxygen conditions, which we recently reported in a previous paper, were carried out together with a study of the reaction route, the nature of the catalytic active sites, and the effect of the support. In our previous paper, we reported significantly improved activity for oxidative esterification using commercially available 5%Pd/Al2O3 at 1.5 MPa of O2 gas and 333 K and emphasized that the doping of 5%Pd/Al2O3 with lead was not needed for the reaction system, but we could not improve the activity that was reported when using 5%Pd/ -Al2O3 doped with 5% Pb (a 93.2% conversion of propionaldehyde, 76.8% selectivity for methyl propionate and a 71.6% yield of methyl propionate) at 0.3 MPa of O2 gas and 353 K, as reported by another laboratory. In the present study, however, we exceeded those values and obtained a 98.3% conversion of propionaldehyde, 75.3% selectivity for methyl propionate and a 74.0% yield of methyl propionate using 5%Pd/ -Al2O3 undoped with Pb at 1.5 MPa of O2 gas and 333 K. It should be noted that, in the preparation of the present 5%Pd/ -Al2O3, Pd was doped onto Al2O3 that had been previously treated with aqueous NaOH. Another active alumina support, -Al2O3, prepared from boehmite, afforded activity that was substantially lower than that of -Al2O3 and depended on the calcination temperature of boehmite to -Al2O3. When using various concentrations of CH3OH in the aqueous reaction solution, the oxidative esterification proceeded through the formation of propionic acid. To determine why Al2O3 support afforded better activity than active carbon support, Pd/Al2O3 and Pd/C catalysts were examined by XAFS (X-ray absorption fine structure). XAFS revealed that Pd on Al2O3 shows a better redox nature than Pd on C, which resulted in activity on Pd/Al2O3 that was better than that on Pd/C.

表題反応の最適化を重金属で修飾していないパラジウム触媒を用い酸素加圧下の条件下で行った．さらに反応機構，活性座についての検討，担体効果についても検討した．γーアルミナに担持したパラジウム触媒において，プロピオン酸メチルの収率が74%に達成し，市販品触媒の活性を上回った．ベーマイトから調整したη-アルミナを担体とした場合，上記の収率を超えることはできなかったが，ベーマイとの焼成温度に触媒活性は依存した．溶媒効果や関連化合物の反応挙動により，この反応に対してはプロピオン酸を経て進む反応機構が提案された．XAFSの検討から担体のレドックスが触媒活性に影響を与えていることが明らかになった．


Preparation of nitrogen-doped porous carbon and its water adsorption behaviour


Uniform nanoparticles of hydrotalcite-like materials and their textural properties at optimized conditions of urea hydrothermal treatment


IR SPECTROSCOPIC ANALYSIS OF THERMAL BEHAVIOR OF ADSORBED WATER ON Y-TYPE ZEOLITE

International Journal of Modern Physics: Conference Series


HYDROGEN PERMEABILITY OF PALLADIUM MEMBRANE FOR STEAM-REFORMING OF BIO-ETHANOL USING THE MEMBRANE REACTOR


CONTROL OF NANOPARTICLE SIZE, CRYSTAL STRUCTURE AND GROWTH OF LAYERED DOUBLE HYDROXIDE BY HYDROTHERMAL TREATMENT


Preparation of nitrogen-doped porous carbon by ammonia gas treatment and the effects of N-doping on water adsorption


Effects of the organic solvent in carrier gas on the prepared TiO2 thin film by metal-organic chemical vapor deposition method

International Journal of Modern Physics B


IN SITU HIGH TEMPERATURE FT-IR STUDY OF THE INTERLAYER NAPHTHALENE-2,6-DISULFONATE IN Mg AND AL LAYERED DOUNLE HYDROXIDE


Influence of Particle Size on Anti-Adhesion Effect of Surface Polished Steel Plate

表面研磨処理を施した鋼板の粉体付着抑制効果に及ぼす粒子径の影響

In this paper, we examined the influence of particle size on anti-adhesion effect of a surface polished steel plate. SiO2 spherical powders and stainless steel plates with seven kinds of surface roughness were used for the investigation. The adhesion tests of SiO2 powders to the polished stainless steel plates were performed using powders of nominal size 9 and 13μm. In the case of 13μm powder, the obvious adhesion and deposition of powder was not observed for all steel surface conditions. However, strong adhesion of particles and thin deposition layers were observed for 9μm powder, being independent of surface roughness of the steel plates. The size of adhered particles on the steel plate were measured by SEM observations in order to examine the adhesion mechanism of SiO2 particle to the polished stainless plate substrate. As a result, adhesion of 3-5 μm particles to the steel surface was largely independent of surface roughness. The adhesion of 3-5 μm particles can be avoided by mixing of small particles of 0.5μm powder into 9μm powder.

Transactions of The Japan Society of Mechanical Engineers, Series C

日本機械学会論文集(C編)


A new adsorption-desorption model for water adsorption in porous carbons


XPS Study of the Influence of CO2 on H2 Flux through a Composite Membrane Made of Palladium and Porous Stainless Steel

Plating a Pd membrane on the outer surface of a porous stainless steel (PSS) tube facilitates rapid H2 permeation with an absolute selectivity; the permeation is based on the solution-diffusion transport mechanism. Reforming of carbon hydride is a well-known method of manufacturing H2. CH4 dry reforming is performed in a membrane reactor using a thin Pd membrane. In this reaction, chemisorbed CO2 is known to affect H2 permeation behavior. The effect on H2 permeation and membrane stability were investigated by performing a permeation test and by XPS. After H2 was permeated through the Pd membrane, CO2 was flowed over the membrane for 1 h, and H2 was once again permeated through the membrane. In the experiment, the temperatures were 623, 723, and 823 K, the differential pressure was 0.1 MPa, and the feed rate was 10 mL/min. CO2 was replaced by He and the experiment was performed under the same conditions. After the second H2 permeation, the H2 flux increased with the time and attained its original value. The time required to attain the original value was dependent on the gas and the temperature. In the case of the He flow, the time required was only 5 min and was independent of the temperature. On the other hands, in the case of the CO2 flow, the required times were 10 min and 25 min at 623 K and 723 K or 823 K, respectively. After the CO2 flow, the XPS spectra of the surface of the Pd membrane were measured. The spectra showed that PdO was formed on the Pd membrane by oxidation of the Pd surface. The PdO was formed by chemisorbed CO2, and the H2 permeability was degraded by PdO; however, PdO was easily reduced to Pd by the H2 flow. When the experiment involving CH4 dry reforming was performed in the Pd membrane reactor with conventional Pt-based catalysts and a sweep gas for 12 h at 873 K, the H2 flux, H2 selectivity, and H2 recovery were ca. 6 mL/min, 98% (calculated by excluding the sweep gas), and 80%, respectively.

Journal of Chemical Engineering of Japan


Behavior of steam reforming reaction for bio-ethanol over Pt/ZrO2 catalysts


Influence of Surface Polishing of Steel Plate on Adhesion/Heap Behaviour of Silica Powder

シリカ粉体の付着・堆積挙動に及ぼす鋼板表面研磨処理の影響

In this paper, we examined the relationship between surface roughness and particle adhesion behavior by a proposed experiment. Five kinds of SiO_2 spherical powders (powder diameter: 0.2, 0.5, 1.0, 1.5 and 2.0μm) and stainless steel plates with seven kinds of surface roughness were used for the invetigation. The effect of humidity, electrostatic force and van der Waals force on the particle-steel adhesion behavior was also examined. The experimental results showed that van der Waals force was relatively important to the adhesion behavior compared with two other effects. The adhesion ratios of SiO_2 powders to polished stainless steel plates were measured. The adhesion ratios depend on the surface roughness and the particle diameters. The adhered particles on the steel plate were observed by SEM in order to examine the adhesion mechanism of SiO_2 particle on the polished stainless plate substrate. As the result, 0.4-1.0μm particles were easy to adhere independent of surface roughness and nominal powder diameter. The result indicates that adhesion behavior of powder depends on the adhesion force of 0.4-1.0μm particles that are changed by the surface roughness of the steel plate.

日本機械学会論文集(C編)


Photocatalytic activity of nitrogen and fluorine co-doped titanium dioxide prepared using of various pH solutions


The effect of carbon monoxide on the hydrogen permeability of a palladium membrane


Characteristics and humidity control capacity of activated carbon from bamboo

Activated carbons were prepared from bamboo by chemical activation with K2CO3 or physical activation with CO2. The structural and surface chemical characteristics of the activated carbons were determined by N2 adsorption-desorption and Boehm titration, respectively. The water vapor adsorption properties of the activated carbons with various pore structures (preparation conditions) were examined. The relationship between water vapor adsorption capacity and pore properties, and the humidity control capacity of the prepared activated carbons are also discussed. The water adsorption isotherms show a region of rapidly increasing uptake of water vapor, and the relative humidity corresponding to those regions was different according to the preparation conditions, especially activation temperature. Water vapor adsorption capacity was improved with larger pore volume and surface area, but the humidity control capacity in a certain specific humidity region differed greatly according to the relative humidity corresponding to the steeply rising regions of the isotherms. In the typical operating conditions of an adsorption heat pump, RH 10-35%, the bamboo-sourced activated carbon that was prepared at 873K by potassium carbonate activation with impregnation ratio 1.0 had the highest humidity control capacity.


Synthesis of light olefins from bio-ethanol over Ni-MFI catalysts

Ni-MFIゼオライト触媒によるバイオエタノールからの低級オレフィン合成

The effects of Ni addition on the catalytic activity of MFI zeolite catalysts were examined with the ethanol conversion reaction under high space velocity conditions, using pure ethanol, ethanol diluted with water, and bioethanol produced from corn, and the effects of impurities on deactivation were evaluated. Addition of Ni to MFI zeolite strongly suppressed the formation of aromatic compounds, and greatly improved the selectivities for C3 and C4 olefins from pure ethanol, but decreased the selectivities for C3 and C4 olefins, and slightly reduced the suppression effect of the Ni site for aromatic formation from bioethanol. The yields of C3 and C4 olefins decreased with time-on-stream despite the presence of the Ni sites. XPS analysis of the catalysts after reaction at 673 K showed presence of oxidized carbon species, indicating the deposit of the impurity from the bioethanol. In addition, the electronic state of Ni after the reaction of bioethanol was also different to that after the reaction of reagent ethanol. XPS analysis showed the formation of Ni2O3 species or nickel sulfate during the reaction of bioethanol, which caused catalyst deactivation. In the reaction at 773 K, a large amount of filament carbon was deposited on the catalyst surface. These factors caused significant decreases in the formation of C3 and C4 olefins in the conversion of bioethanol.

Ni-MFIゼオライトを用いて，高い空間速度下でのエタノール転化反応に及ぼすNi添加効果を検討した．さらに，トウモロコシから生成された実バイオエタノールに対する反応性や失活に及ぼす水や微量不純物の影響を考察した．MFIへのNiの添加は芳香族化合物生成を強く抑制する効果を示し，純エタノールの反応ではC3およびC4オレフィンの生成選択性を大幅に向上させた．一方，バイオエタノールを反応物とすると，C3およびC4オレフィンの生成選択率は減少し，Niサイトの芳香族生成抑制効果がやや低下した．また，Ni添加の有無にかかわらずC3∼C4オレフィン生成量が経時的に減少した．673 Kにおける反応では炭化水素以外の炭素種の表面堆積が認められ，バイオエタノール中の不純物の堆積が示された．Niの電子状態は純エタノールの反応後と異なっており，ニッケル硫酸塩あるいはNi2O3種の生成が触媒劣化にかかわっていることが示唆された．773 Kでの反応では，触媒表面に大量のフィラメント状の炭素が析出した．これらの要素が実バイオエタノールの反応におけるC3，C4オレフィン生成反応の特異的な失活を導いている可能性がある．

Journal of the Japan Petroleum Institute


Performance of a bench scale annular type packed bed photocatalytic reactor for decomposition of indigo carmine dissolved in water

A bench-scale annular-type packed-bed photocatalytic reactor with TiO2-coated glass beads as the photocatalyst was designed; the performance of the reactor was evaluated by using it for the photocatalytic decomposition of indigo carmine (IC) dissolved in water. The reactor was operated in a recirculation batch mode, and the dye solution in the reservoir was recirculated through the photocatalyst bed in the annular space of the reactor. The concentration of the dye in the reservoir decreased gradually with an increase in the operation time. The time course of the change in the IC concentration was calculated numerically by assuming first-order kinetics, and the overall rate constant of photocatalytic decomposition was determined by fitting the calculated time course to the experimental value obtained for various treatment times. The overall decomposition rate constants decreased with an increase in the initial concentration of the IC solution. The rate-controlling step in the photocatalytic decomposition was the mass transfer of IC from the bulk of the solution to the catalyst surface when the flow rate was less than 1 dm3/min; however, when the flow rate exceeded the transition flow rate, the reaction occurring at the catalyst surface was the rate-controlling step.


水分子吸着による人工衛星光学硝材の透過率変動計測

水分子吸着による人工衛星光学硝材の透過率変動計測

Gas adsorption onto optical surfaces equipped in satellites is one of the causes of signal degradation occurred in orbit and water is one of the most potent ad-molecules. To estimate the degradation caused by water adsorption onto optical glass surface, the transmittance measurements were carried out in UV-VIS (200--800nm) and IR (1.7--20μm) wavelength ranges. Five kinds of glasses, SiO2, BK7, Al2O3, CaF2, and ZnSe, which are typically used for satellite optics, were selected as glass samples. In IR wavelength range, a local absorption feature was appeared at λ=3.1μm when a glass temperature was below 200K. The phase change of adsorbed water from vapor to solid may account for the newly appeared absorption. In UV-VIS region, there was no local absorption feature but broad transmittance decrease. BK7 and ZnSe, which are hydrophobic, showed little transmittance decrease and it was hard to find the wavelength dependence for their transmittance spectra. On the other hand, the transmittance spectra of hydrophilic glasses, SiO2, Al2O3, and CaF2, showed wavelength dependence and had the local minimal value. From our computation, it is found that the growth of ice grains on a glass surface makes it possible to reproduct the spectral transmittance degradation detected for hydrophilic glasses.

Journal of the Japan Society for Aeronautical and Space Sciences


Nanocomposites of 2-arylpropionic acid drugs based on Mg-Al layered double hydroxide for dissolution enhancement

Naproxen (NP) and flurpibrofen (FB) as non-steroidal anti-inflammatory drugs (NSAIDs) of 2-arylpropionic acid derivatives have been used as host organic drugs to be intercalated into layered double hydroxide (LDH) applying reconstruction and co-precipitation techniques. The obtained NP LDH and FB LDH nanocomposites were characterized by X-ray powder diffraction, infrared and thermogravimetric analyses. From drug loading, thermal analysis and X-ray measurements we can decide that coprecipitaion technique is better than reconstruction technique to obtain intercalated monophase nanocomposites. In acidic medium LDH dissolved and the intercalated drug starts to release in a molecular form which is suitable for adsorption. The drug solubility has been investigated before and after intercalation. It has been found that LDH improves the drug solubility and its dissolution rate.

European Journal of Pharmaceutical Sciences


Effect of Organic Contaminants on Satellite Optics Transmittance Variation due to the Adsorption of Organic Molecules on Optical Glass Surfaces

衛星光学系への有機系汚染物質の影響-有機分子吸着による光学硝材の透過率変動-

Transactions of the Society of Instrument and Control Engineers


Adsorption properties and photocatalytic activity of TiO2 and La-doped TiO2


Conversion of Bio-ethanol into Hydrocarbons over HZSM-5 catalyst

HZSM-5触媒によるバイオエタノールからの炭化水素の合成

The conversion of bio-ethanol (ethanol: 77.4%, water: 19.6% and trace) derived from corn into hydrocarbons over HZSM-5 zeolites was studied. The reaction behaviors for formation of gaseous olefins and aromatics at WHSV=26 h-1 at 573 773 K were discussed by comparing with those of pure ethanol and 80% ethanol aqueous solution. The main products in the bio-ethanol conversion were ethylene or diethyl ether, and C3 C5 hydrocarbons and aromatics were also produced. The selectivity of olefins formation in C3 C4 hydrocarbons was depends on the reaction temperature. The yields of C3 C4 olefins increase with the rise of reaction temperature. The formation of them from bio-ethanol needs higher temperature than that from ethanol, and the decline of activity for bio-ethanol conversion was observed faster than that for a pure ethanol and an ethanol/water solution. The reason was explained by the strong acid site of HZSM-5 was poisoned by impurities in bio-ethanol such as sulfur. The content of aromatics was the largest at 648 K, but it decreased at 673 K. The order of amounts of aromatics produced were from pure ethanol>bio-ethanol>ethanol/water solution. The coexistence of water depressed the amount of aromatics, but the active sites changed by impurities in bio-ethanol promoted the formation of aromatics.

実バイオマスから生成したバイオエタノール(エタノール:77.4%，水:19.6%，その他;残渣)を原料として，HZSM-5ゼオライト触媒を用いて転化反応を行い，C3およびC4の低級オレフィンおよび芳香族化合物の生成に関する特性を，純エタノールおよび含水エタノール(水:20%)からの転化反応と比較検討した．573–773 K，WHSV=26 h-1の条件では，バイオエタノールからの主生成物は，エタノールから脱水反応で容易に生成するエチレンあるいはジエチルエーテルであったが，623 K以上ではC3–C5の炭化水素およびC6以上の芳香族炭化水素も比較的多く生成された．低級オレフィンの生成量は反応温度につれて増加したが，バイオエタノールを反応物とした場合には，モデル反応物に比べて生成活性の発現温度がより高温側にシフトするとともに，やや大きい経時的失活が認められた．この原因として，バイオエタノール中のトレース量の不純物が触媒の酸性質を変化させた可能性が高い．バイオエタノールからの芳香族化合物の生成量は，純エタノールの場合より減少したが，バイオエタノールと同程度の水を含有するエタノール水溶液よりは多くなった．これは，高SV条件下での水の共存が芳香族生成抑制の効果を示すのに対して，バイオエタノールに含まれる不純物が触媒活性点を改質したため，含水エタノールよりも芳香族化合物の生成量が増加したと考えられる．


Preparation and characterization of nitrogen-doped mesoporous titania with high specific surface area


Development of Transmittance Variation Measurements Systems Owing to Molecular Adsorption

光学系への分子ガス吸着による透過率変動計測装置の開発

Journal of the Remote Sensing Society of Japan

日本リモートセンシング学会誌


Characterization of Palladium and Palladium-Silver Alloy Layers on Stainless Steel Support

International Journal of Modern Physics B


FTIR Study on Molecular Contamination on Surface of Optical Materials


Photocatalytic Reaction of Acetone on Mesoporous Chromium Silicate


Total Oxidation of Activated Carbon over PdO-CeO2/TiO2-Al2O3 Catalyst


Spectroscopic study for photocatalytic decomposition of organic compounds on titanium dioxide containing sulfur under visible light irradiation

Yellowish S-containing TiO2 (S-TiO2) powders were prepared by calcination of a mixture of titanium(III) chloride and ammonium thiocyanate solutions. Three kinds of S-TiO2 were prepared by varying the concentration of ammonium thiocyanate (0.5, 1 or 13 M). X-ray photoelectron spectroscopy spectra of the S-TiO2 showed that sulfur atoms existed on the surface of TiO2 powders. But the peaks assigned to S disappeared after Ar+ etching, which means that these atoms were not doped in the bulk of the TiO2 powders. While UV-visible absorption spectra of S-TiO2 showed that the absorption edges of these photocatalysts were seen to shift to a longer wavelength (lower band gap energy) than those of undoped rutile TiO2 prepared and commercial anatase type TiO2 (ST-01). The S-TiO2 (1 M) exhibited higher photocatalytic activity than ST-01 for degradation of methylene blue in aqueous solution under visible light irradiation (lambda > 400 nm). It was also confirmed by IR spectroscopy that acetaldehyde in oxygen under visible light irradiation (lambda > 400 nm) was decomposed to acetic acid by the S-TiO2 and ST-01 at the first decomposition step.

Journal of Colloid and Interface Science


Adsorption and Photocatalytic Decomposition of Volatile Organic Compounds on Photocatalyst of TiO2-silica beads


Adsorption Properties of Nitrogen, Carbon Dioxide and Nitorgen Dioxide onto Mesoporous Chromium Silicate


Catalytic Activity of Iron Oxides Supported on γ-Al2O3 for Methane Oxidation

Three kinds of catalysts of goethites supported on γ-Al2O3 (Fe/γ-Al2O3), SiO2-Al2O3 (Fe/SiO2-Al2O3) and SiO2 (Fe/SiO2) were investigated in terms of the catalytic activity of methane oxidation. The specific surface areas of these catalysts were larger in common than the area of goethite with no supports. The Fe/γ-Al2O3 catalyst has the highest performance in the low-temperature activity of methane oxidation which started at 623 K and completed at 923 K. When the Fe-content in Fe/γ-Al2O3 was increased, the formation of goethite was observed by the X-ray analyses and the activity of this catalyst increased up to 6 mol%. After the catalytic methane oxidation at 823 K, it was observed that goethite in Fe/γ-Al2O3 transformed to hematite which has been known as an active iron oxide in methane oxidation. The activity of Fe/γ-Al2O3 was enhanced by the addition of sodium up to the Na-content of 5 mol% although it descended above the content due to the decrease of the specific surface area of the catalyst.

Journal of the Japan Petroleum Institute


Adsorption Properties of Gases onto Mesoporous Chromium Silicate

クロムを含有するメソポーラスシリカ(Cr-FSM-16)のガス吸着特性を検討した．珪素とクロムの比(Si/Cr比)が170と390のCr-FSM-16は，クロムを含まないFSM-16と細孔径は変わらなかったが，比表面積が2/3程度に減少した．窒素のCr-FSM-16への初期吸着熱はFSM-16にくらべ大きくなったが，二酸化炭素のCr-FSM-16への初期吸着熱はFSM-16にくらべ小さくなった．また，Cr-FSM-16は，光を照射しない条件下でも二酸化窒素を分解することがわかった．


Direct Detection of a Phase Change in PdO/CeO2 Supported on χ-Al2O3 by means of in situ High-Temperature Measurements of XRD and FTIR

本論文では，メタン酸化反応におけるc-Al2O3担持PdO/CeO2触媒でのPdOからPdへの変化をXRD及びFT-IRの高温その場測定により直接に観測した．この変化は雰囲気中の酸素分圧変化に対して可逆的であり，この変化がメタン酸化における触媒作用の本質であると結論した．この結論はこれ迄の研究結果をよく説明するものである


Effects of Sulfate Ion on Crystal Structure and Activity for Methane Oxidation of Iron Oxide Prepared from Goethite

ゲータイトから調製した酸化鉄の結晶構造とメタン酸化活性に及ぼす硫酸イオンの影響

ゲータイトを前駆体として合成した酸化鉄を用いてメタン酸化活性試験を行った．酸化鉄によるメタン酸化活性は硫酸イオンの存在で抑制されることを明らかにした．この活性の低下は鉄原子に電子を供与して鉄の酸化力を減少させることにより引き起こされるが，同時に硫酸イオンは酸化鉄中に多くの酸素欠陥を酸化鉄格子中に導入するので，硫酸イオンが脱離するような550℃以上の高温では逆に活性が向上することを見いだした．


The Control of Pore Structure and Adsorption Characteristicsof Mesoporous Silicas

メソ多孔性シリカの細孔構造の制御と吸着特性

To modify the adsorption characteristics of the mesoporous silica FSM-16, Al-incorporated FSM-16 (Al-FSM-16) and trimethylsilylated FSM-16 (TMS-FSM-16) were prepared. The pore structureand the adsorption characteristics of these modified mesoporous materials were examined by usingprobe molecules of N2 and CO2. BET surface area of Al-FSM-16 was reduced to 470 m2·g-1, about one-half of the surface area of FSM-16. However, the separation factor for CO2 from CO2-N2 gas mixtures (CO2/N2=20.1/79.9) on Al-FSM-16 was higher than on FSM-16 in the total pressure range from 0.2 to 0.3 MPa. This implies that CO2 is adsorbed selectively to Na+, which is present to compensate for thenegative charge generated by incorporating Al in the framework of the mesoporous silicas. By trimethyl-silylation of FSM-16, 82% of the surface area was covered with trimethylsilyl (TMS) groups, and thepore size decreased to 2.3 nm from the 2.8 nm of FSM-16. Much less CO2 was adsorbed on TMS-FSM-16 than that on FSM-16, possibly due to the smaller amount of free SiOH groups of TMS-FSM-16.

メソ多孔性シリカであるFSM-16の骨格にAlを導入したAl-FSM-16およびシリル化処理を施したTMS-FSM-16を調製し，その細孔構造と吸着特性について，窒素および二酸化炭素をプローブ分子として検討した．Al-FSM-16の比表面積はFSM-16にくらべ半分程度になったが，二酸化炭素と窒素との混合気体を吸着させると，二酸化炭素の分離係数が FSM-16にくらべ2倍以上大きくなることを見出した．FSM-16のシリル化では，メソ孔内表面の82%がTMS基により被覆され，細孔径が2.8nmから2.3nmに減少した．


Adsorption Selectivity of FSM-16 for Several Organic Compounds

メソ多孔性シリカであるFSM-16を調製し，数種の有機化合物(p-ニトロフェノール，トルエン，n-ヘプタン，ベンゼン，シクロヘキサン，o-ジクロロベンゼン)の吸着選択性を検討した．水溶液中のp-ニトロフェノールは，FSM-16にほとんど吸着しなかったが，n-ヘプタン中のトルエンやベンゼンはFSM-16の細孔内に吸着することがわかった．また，これらの吸着量は，市販の吸着剤(13Xゼオライトやシリカゲル)にくらべ多いこともわかった．


Binding Properties of a Water-Soluble Chelating Polymer with Divalent Metal Ions Measured by Ultrafiltration. Poly(acrylic acid)

本論文は水溶性キレートポリマーであるポリアクリル酸と二価金属イオン(Co(II), Ni(II), Cu(II), Zn(II), Pb(II))との結合平衡関係をバッチ式限外濾過法によってpH4-6の範囲で求め，錯形成モデルを提案し，提案したモデルによって結合平衡関係を良く表すことができることを示したものである．逐次錯安定度定数および平衡定数を実験値とのカーブフィティングによって求め，文献に報告されている種々の方法によって決定された錯安定度定数と比較し，提案したモデルが妥当なものであることを明らかにした．また，モデルに基づいて逐次的に生成する錯体濃度を推算して求めた平均配位数とpHの関係についても考察したものである．

Industrial & Engineering Chemistry Research


In Situ XRD and In Situ IR Spectroscopic Analyses of Structural Change of Goethite in Methane Oxidation

含水酸化鉄の一種であるゲータイトのメタン酸化活性について調べた．ゲータイトは針状結晶であるが，220∼230℃付近で脱水により比表面積の非常に大きい酸化鉄であるヘマタイトに相変態をすること，その比表面積の大きいヘマタイトがメタン酸化に大きく関わっていることをその場観察X線回折およびその場観察赤外分光法により明らかにした．


Adsorption of CO2 on FSM-type mesoporous silicas

細孔径(1.7nm:FSM-10，2.1nm:FSM-12，2.3nm:FSM-14，2.8nm:FSM-16)の異なる4種のFSMタイプのメソ多孔性シリカを調製し，二酸化炭素の吸着特性について検討した．二酸化炭素の吸着熱からFSM-10とFSM-12の吸着サイトはエネルギー的に均一であるが，FSM-14とFSM-16にはエネルギー的に異なる吸着サイトが存在することがわかった．そして，そのエネルギー的に異なる吸着サイトは，IRスペクトルで観測された自由シラノール基の存在が原因と判断した．


Adsorption Characteristics of Ion-Exchanged ZSM-5 Zeolites for CO2/N2 Mixtures

Adsorption characteristics of alkali metal ion-exchanged ZSM-5 zeolites, M-ZSM-5 (M=Li, Na, K, Rb, and Cs), for CO(2)/N(2) mixtures were investigated by a column method and IR study. It was shown that CO(2) was adsorbed from CO(2)/N(2) mixtures on M-ZSM-5 zeolites by two types of adsorbtion at temperatures below 333 K. One was a weak adsorption due to interaction with the wall of ZSM-5, and the other was a strong adsorption caused by interactions with the cation of ZSM-5. IR-spectra of gases adsorbed at various temperatures revealed that the CO(2) were strongly adsorbed on M-ZSM-5 in several ways, which seemed to be caused by different adsorption sites. At temperatures above 373 K, almost all CO(2) adsorbed were on cation sites, while N(2) coadsorbed with CO(2) was shown to interact with the wall of ZSM-5 under all experimental conditions. Copyright 2000 Academic Press.

アルカリ金属でイオン交換したZSM-5ゼオライトの二酸化炭素と窒素の混合気体の吸着特性をカラム法とIRを使って検討した．333K以下では，2種類の吸着タイプがあることがわかった．ひとつは，ZSM-5の壁との弱い吸着，もうひとつはZSM-5のカチオンとの強い吸着であり，それは，IRスペクトルの結果とも一致した．なお，373K以上では，大部分の二酸化炭素はカチオンサイトに吸着し，窒素はZSM-5の壁に吸着することがわかった．

Journal of Colloid and Interface Science


Effect of Temperature on Air Adsorption onto Alkali Metal Ion-Exchanged ZSM-5 Zeolites

Na-ZSM-5から通常のイオン交換法により，アルカリ金属でイオン交換したZSM-5ゼオライトを調製し，空気の吸着能を，クロマトグラフ法によって溶出曲線を決定することにより検討した．吸着ガスとカチオンとの相互作用は吸着ガスのIRスペクトルから考察した．その結果，空気中の窒素が選択的に吸着されることがわかった．また，IRスペクトルから，空気中の窒素が優先的にカチオンサイトに吸着することが示された．


IR Spectroscopic Study of Adsorption of Binary Gases over Ion-Exchanged ZSM-5 Zeolites

アルカリ金属でイオン交換したZSM-5ゼオライトの2成分系ガス(メタン/一酸化炭素，一酸化炭素/一酸化窒素，一酸化窒素/二酸化炭素)の吸着特性をIR分光法を用いて検討した．一酸化炭素のIRバンドのプロファイルは共存ガスによって異なり，これは，吸着選択性が吸着質の極性だけでなく，異なる電場強度をもつZSM-5の細孔構造に起因する吸着サイトの性質が影響していることを示唆した．


Transient Analysis of Mass-Transfer Rate in Recovering Metal Ions Using a Microporous Hollow Fiber Membrance and a Water-Soluble Chelating Polymer

本論文は，多孔質中空糸膜と水溶性キレートポリマーを用いて水溶液中から重金属を回収·濃縮する方法において，過渡応答法によって金属イオンの膜透過速度を求めたものである．金属イオンは水溶液側から膜の孔内を拡散して水溶性ポリマー液側に移動し，ポリマーと錯形成する．そこで，金属イオン濃度を過渡的に変えることによって，中空糸膜の中空側を流れるキレートポリマーの出口濃度を解析して金属イオンの膜透過の総括物質移動係数と混合拡散係数を決定し，水溶性キレートポリマーの中空内流速との関係を明らかにした．


イオン交換ZSM-5ゼオライトへのクロロジフルオロメタンの吸着

イオン交換ZSM-5ゼオライトへのクロロジフルオロメタンの吸着

種々のアルカリ金属イオン交換ZSM-5ゼオライトにクロロジフルオロメタンを吸着させ，その吸着特性を検討した．吸着温度273Kの条件では，クロロジフルオロメタンはZSM-5細孔内で液体に近い密度で物理吸着しているが，その吸着熱はゼオライト中のカチオン種によらず凝縮熱に比べて著しく大きく，吸着分子が細孔壁からの引力を強く受けていることが示された．しかし，吸着分子の微視的な性質はゼオライト中のカチオンの静電場の影響を強く受けていることがわかった．


Analyses of n1-Band of Methane Adsorbed on Ion-exchanged L-Zeolites

L型ゼオライトのカチオンサイトの性質を明らかにするために，吸着したメタンのIRバンドを解析した．ピークシフトと電場強度，ピークシフトとモル吸光係数の関係は，摂動理論に基づいて解釈することができた．また，メタン吸着可能なカチオン数は，カリウムやルビジウムでイオン交換したL型ゼオライトで，ユニットセルあたり3原子と見積もられた．


アルカリ金属イオン交換ZSM-5ゼオライトへの二酸化硫黄の吸着

アルカリ金属イオン交換ZSM-5ゼオライトへの二酸化硫黄の吸着

種々のアルカリ金属イオンでイオン交換したZSM-5に二酸化硫黄を吸着させ，吸着量測定および種々の分光学的測定(IR，XPS，XRF)と吸着相互作用ポテンシャルの理論計算を行い，吸着状態の解明を行った．理論計算結果は物理吸着した二酸化硫黄に二つの安定な吸着構造が存在することを示唆し，IR測定によってその存在が確認された．


Infrared studies on nitrogen oxides adsorbed on alkali metal ion-exchanged ZSM-5 zeolites

アルカリ金属イオンでイオン交換したZSM-5ゼオライトへの種々の窒素酸化物の226Kでの吸着特性を赤外分光法で検討した．一酸化窒素の分圧が低い条件では，一酸化窒素は直線的にZSM-5のカチオンサイトに吸着するが，分圧の増加にともない，不均化が起こり，一酸化二窒素や三酸化二窒素が生成することがわかった．


IR Spectra for Adsorbed CO on Various Alkali Metal Ion-Exchanged ZSM-5 Zeolites

アルカリ金属イオンでイオン交換したZSM-5ゼオライトへ一酸化炭素を吸着させ，その状態を赤外分光法により測定し，吸着した一酸化炭素のピーク位置や強度の温度による影響を考察した．IRスペクトルから，物理吸着した一酸化炭素はカチオンに直線的に配向しており，弱く吸着している一酸化炭素はZSM-5の細孔壁と相互作用していることがわかった．

Bulletin of the Chemical Society of Japan


Adsorption of CO2 over univalent cation-exchanged ZSM-5 zeolites

二酸化炭素をアルカリ金属イオンでイオン交換したZSM-5に吸着させ，その吸着量とIRスペクトルを測定した．観測された吸着特性は，物理吸着を仮定した理論計算とよく一致し，化学吸着は全吸着の10%以下であった．二酸化炭素はカチオンと細孔壁の両方と相互作用したが，カチオンと相互作用した二酸化炭素のみが赤外不活性な二酸化炭素の吸収を活性にすることがわかった．


Synthesis of Versatile Chemicals through Oxidative Dehydrogenation on Solid Catalysts of Non-Petroleum Resource

To prepare 1,3-butadiene, one of versatile chemicals, from 1-butene, one of the main components in liquefied petroleum gas (LPG), the oxidative dehydrogenation of 1-butene on -Bi2Mo3O12 doped with cerium was examined. Regardless to the doped amount of cerium, the conversion of 1-butene was constant while the selectivity to 1,3-butadiene decreased with the doped amount of cerium, while the selectivities to 2-butenes, CO and CO2 increased. It is concluded that the introduction of cerium into -Bi2Mo3O12 resulted in the enhancement of the greater acidic nature of the catalyst while the mild acidic nature of the catalyst seems to be suitable for the effective synthesis of 1,3-butadiene from 1-butene via the oxidative dehydrogenation.

Bulletin of Institute of Technology and Science, The University of Tokushima


高酸化活性を有する酸化鉄触媒の創製と複合化による高機能化

高酸化活性を有する酸化鉄触媒の創製と複合化による高機能化

Bulletin of Faculty of Engineering, The University of Tokushima