Key Factors for the Separation of Silicon and Iron during Phosphorus Recovery from Slag Discharged from the Double-Slag Refining Process

In the present study, we developed a technology for concentrating and recovering phosphorus from slag-like phosphorus-containing unused resources and applied it to slag discharged during the latest steelmaking process, that is, double-slag refining process (DRP). The technology we developed consists of the following four processes: Process (1) is the initial acid elution; Process (2) involves alkali precipitation; Process (3) is the second acid elution; and, Process (4) utilizes ion-exchange. In Process (1), the addition of DPR slag to 0.5 M of a nitric acid solution for 24 min resulted in sufficient phosphorus dissolution. In Process (2), ammonia was added to the dissolved solution, and phosphorus was precipitated with high efficiency. The timing of the addition of ammonia significantly influenced the removal of silicon and iron, which would have been inconvenient to accomplish in subsequent processes. In Process (3), the precipitation obtained in Process (2) was re-dissolved in a nitric acid solution. The dissolution of phosphorus together with other elements progressed sufficiently, and we confirmed that silicon could be completely separated as silica by using high-concentration nitric acid at this stage. The fact that silicon could be removed during Process (3) was an important finding, since silicon could not have been separated in the Process (4). In Process (4), by passing the phosphorus-containing solution obtained in Process (3) through an ion exchange resin, elements other than phosphorus and silicon could be removed, which confirms that the range of applications for this technology could be expanded.


Regeneration of Alumina-Supported Nickel Oxide Catalyst Covered with Large Amounts of Carbon Deposits During the Dehydrogenations of Ethane, Propane, and Isobutane

Improvement in the dehydrogenations of ethane, propane, and isobutane over alumina-supported nickel oxides have been reported along with the formation of large amounts of carbon deposition with time-on-stream, but catalyst activity is decreased with an additional increase in time-on-stream. This improvement in activity is due to metallic nickel that is highly dispersed over carbon nanotube-like depositions. When this highly dispersed metallic nickel is further covered with carbon deposits, the activity decreases. In this paper, we describe the result of oxygen treatment to regenerate the catalyst. It is generally accepted that oxygen treatment, to remove carbon depositions, results in a less active catalyst due to sintering of the active species. We speculated, however, that sintered nickel oxide could form carbon nanotubes in the proposed system, and that the formation of highly dispersed nickel over the nanotubes would regenerate the catalyst. To prove this hypothesis, the dehydrogenations of ethane, propane, and isobutane were investigated using 18, 15, and 20% nickel oxide supported on γ-alumina, respectively. We confirmed regeneration of the catalytic activity via oxygen treatment during subsequent dehydrogenations.

アルミナ担持酸化ニッケル触媒によるエタン，プロパン，およびイソブタンの脱水素化では，通塔時間に伴う炭素析出の形成とともに，触媒活性の向上が観察されることが報告されている．この改善挙動はカーボンナノチューブ状析出物上に高分散状態で形成される金属ニッケルに起因されるが，さらに通塔時間を長くすると，カーボンナノチューブ状析出物が通常の炭素析出物によって覆われ，活性が低下する． 本稿では，活性が低下したアルミナ担持酸化ニッケルを酸素処理により再生した結果について述べた． 炭素堆積物を除去するために酸素処理を用いると，活性種のシンタリングより，触媒活性成分が低分散化され，活性が低下することが一般に知られている． しかしながら，本触媒系では，酸素処理でシンタリングした低分散の酸化ニッケルが形成されたとしても，再度接触反応に用いると，そこからカーボンナノチューブが形成され，このナノチューブ上に高分散状態で金属ニッケルが形成され，良好な触媒活性が再生されることが期待される．この仮説を証明するために，エタン，プロパン，およびイソブタンの脱水素化を， -アルミナに酸化ニッケルを 18%，15%，および 20%担持した触媒を用いて検討した．その結果，これら3種類のアルカンの脱水素に対して，本稿で提案した酸素処理による触媒活性の再生が良好に行われることが明らかになった．

Journal of the Japan Petroleum Institute


Effective Dechlorination of 2-Chloropropene to Propylene on a Metallic Nickel Catalyst Supported on γ-Alumina

In our previous paper, we reported that the reductive conversion of 2-chloropropene (2-PEN) on -alumina-supported palladium catalysts showed high activity at 348 K. In this catalyst system, however, 2-chloropropane (2-PAN), propylene, and propane were produced non-selectively, which necessitated a separation process when considering actual industrial development. In the present study, an alumina-supported nickel catalyst achieved a highly selective conversion of 2-PEN to propylene. For example, at 473 K, the propylene selectivity reached 95.7% when the conversion of 2-PEN was 15.0% on the catalyst loaded with 10% nickel. However, since propylene yield was only 14.3%, the reaction was examined at 623K. This resulted in a 75.6% conversion of 2-PEN and a 78.6% selectivity to propylene, which accompanied to a sufficient 59.4% yield. The most notable point was that no propane was produced under these conditions. Therefore, there is no need to separate propane and propylene. We concluded that by using nickel as a catalyst, an excessive reduction of propylene to propane could be suppressed.

前報では，アルミナ担持パラジウム触媒による 2-クロロプロペン (2-PEN) の接触還元が 348 K で高い活性を示したことを報告した．しかしこの場合，2-クロロプロパン(2-PAN)，プロピレンおよびプロパンが非選択的に生成されたので，実際の社会実装を考えると分離プロセス併設が不可欠となっていた． 本研究では，アルミナ担持ニッケル触媒が 2-PEN のプロピレンへの高選択的変換を達成できることを明らかにした． たとえば，473 K では，10% の Ni を担持した触媒を用いると， 2-PEN の転化率が 15.0%，プロピレンの収率は 95.7% に達した． 但し，プロピレン収率が14.3%であったため，623Kで反応を検討した． その結果，2-PENの転化率75.6%，プロピレンへの選択率78.6%となり，プロピレン収率が59.4%となった． 最も注目すべき点は，この条件下でプロパンが生成されなかったことである． したがって，本触媒系では，プロパンとプロピレンを分離する必要はない． ニッケルを触媒として用いることで，プロピレンからプロパンへの過度の還元が抑制されると結論付けられた．


Phosphorus Recovery from Sewage-sludge Molten Slag Using a Combination of Acid-dissolution, Alkali-precipitation, and Ion-exchange

We recently reported an efficient procedure for recovering phosphoric acid from dephosphorization slag. This recovery procedure consists of a combination of the following four processes: (1) A first dissolution process of slag in a nitric acid solution; (2) a precipitation process then adds ammonia to the obtained eluate; (3) a second dissolution process dissolves the precipitation from the nitric acid eluate; and, (4) the final process involves ion exchange in which the obtained eluate is passed through an ion exchange resin. In the present study, this recovery procedure was applied to concentrate and recover phosphorus from sewage-sludge molten slag, which is an unused resource that should be considered a new resource for phosphorus. As a result, our procedure for recovery from dephosphorization slag was viable following two revisions. Initially, the time for the first dissolution process was extended from 0.2 h to 1 h, but 0.2 h proved to be the optimum time for dephosphorization slag. Next, we discovered it was better to perform the filtration one day after adding the ammonia instead of immediately after adding it. The other two processes could be treated under substantially the same conditions as in the case of dephosphorization slag, and high-purity phosphorus was obtained.


Enhancement of the Catalytic Activity Associated with Carbon Deposition Formed on NiO/Al2O3 During the Dehydrogenation of Ethane and Propane

In the recent study, the dehydrogenation of isobutane to isobutene was accomplished using a NiO/ -Al2O3 catalyst, and significant improvement in the time-on-stream yield of isobutene was accomplished. During the normal catalytic dehydrogenation of alkanes, the catalyst is covered by the carbon deposition that is generated during the reaction, which drastically reduces activity with time-on-stream. Therefore, no examples of the catalytic dehydrogenation of isobutane have yet been reported. This study used either ethane or propane as a source of isobutane to examine whether the activity was improved with time-on-stream. As a result, in the dehydrogenations of both ethane and propane on a NiO/ -Al2O3 catalyst, the catalytic activity decreased with time-on-stream when the supporting amounts of NiO was small. By contrast, when the supporting amount of NiO was large, the catalytic activity improved with time-on-stream. The results using a NiO/ -Al2O3 catalyst with small and large NiO loadings were similar to those of isobutane dehydrogenation and it was confirmed that the dehydrogenation activity was improved with time-on-stream in the catalytic dehydrogenations of ethane, propane, and isobutane using large NiO loadings. Intermediate behavior using a moderate amount of NiO loading, which was not detected in the dehydrogenation of isobutane, was also observed, which resulted in a maximum yield of either ethylene or propylene at 2.0 or 3.25 h on-stream, respectively. We concluded that the reason the catalytic activity did not improve with time-on-stream when using a NiO/ -Al2O3 catalyst was because the supporting amount of NiO was too small. These results show that activity with time-on-stream could also be improved in the dehydrogenations of other alkanes.

Journal of Chemical Engineering of Japan


Carbon Deposition Assisting the Enhancement of Catalytic Activity with Time-on-Stream in the Dehydrogenation of Isobutane over NiO/Al2O3

In the transformation reaction of alkanes to alkenes via catalytic dehydrogenation, it is generally accepted that the so-called catalytic deactivation behavior will occur. This phenomenon causes a drastic reduction in activity with time-on-stream. It is understood that carbon deposition generated during the reaction then covers the surface of the catalyst, and this leads to a drastic decrease in activity. However, contrary to this common wisdom, our laboratory reported that the dehydrogenation of isobutane to isobutene on NiO/γ-Al2O3 within a specific range of NiO loading in the presence of CO2 actually improved the yield of isobutene with time-on-stream. Since few such cases have been reported, in this study, isobutane was dehydrogenated in the presence of CO2 using NiO/α-Al2O3 as the catalyst with 20% NiO loading and improvement was again observed. In order to investigate the cause of the improvement, both NiO/γ-Al2O3 and NiO/α-Al2O3 with 20% NiO loading were examined in detail following the reaction. According to TEM analysis, both catalysts were covered with a large amount of carbon deposition after the reaction, but there was a difference in the types. The carbon deposition on NiO/γ-Al2O3 had a fibrous nature while that on NiO/α-Al2O3 appeared to be a type of nanowire. Raman spectroscopy revealed that the carbonaceous crystal growth properties of two forms differed depending on the support. In particular, a catalytically active species of metallic nickel was formed in a high degree of dispersion in and on the above two forms of carbon deposition during the reaction, and this resulted in high activity even if the catalyst was covered with a carbon deposition.


Elution Behavior of Dephosphorization Slag to Various Acids and effect of Addition of Aqueous Alkali to Acid Eluate

We recently developed a method for efficiently recovering phosphoric acid from dephosphorization slag. The most important processes in this recovery technique involve elution of the dephosphorization slag into an acid solution (acid-elution process) and the addition of an alkali to the acid eluate to form a precipitate (alkali-precipitation process). Ultimately, we settled the use of an aqueous nitric acid solution for the acid-elution step, while an aqueous ammonia solution proved to be the optimal choice to accomplish alkali precipitation. Herein, we describe the procedures used to compare the utility of nitric acid with that of hydrochloric acid, sulfuric acid, and citric acid in the acid-elution process, and describe our comparison of an aqueous sodium hydroxide with that of an aqueous ammonia in the alkali-precipitation process. Finally, we summarize our findings on the acids and alkalis that proved to be suitable for this technology.

最近，脱リンスラグからリン酸を効率的に回収する方法を開発した． この回収技術で最も重要なプロセスには，脱リン酸化スラグの酸性溶液への溶出(酸溶出プロセス)と，酸溶出液へのアルカリの添加による沈殿物の形成(アルカリ沈殿プロセス)である． 最終的に，酸溶出ステップに硝酸水溶液を使用することにしたが，アルカリ沈殿を実現するには，アンモニア水溶液が最適な選択であることが明らかになった． ここでは，酸溶出プロセスにおける硝酸の有用性と塩酸，硫酸，およびクエン酸の有用性を比較するとともに，水酸化ナトリウム水溶液とアンモニア水溶液の有用性との比較した． アルカリ沈殿プロセス． 最後に，この技術に適していることが証明された酸とアルカリに関する研究結果を要約した．


Recovery of Phosphoric Acid and Calcium Phosphate from Dephosphorization Slag

We previously reported that by adding aqueous ammonia to the nitric acid extract of dephosphorization slag, a solid with enhanced concentrations of calcium and phosphorus, could be recovered. The present study shows that a considerable amount of manganese and iron also remains, however, which creates difficulties in directly reusing the recovered solid. The recovered material was again dissolved in nitric acid and the resultant filtrate was passed through a cation exchange resin that mostly removed various cations from the yield of an aqueous phosphoric acid solution. The recovery of phosphoric acid was confirmed via 31P NMR. Furthermore, when calcium nitrate was added to this aqueous solution, calcium hydroxyapatite, which was converted to calcium phosphate after the calcination at 1073 K. Phosphoric acid, calcium hydroxyapatite, and calcium phosphate are raw materials that are used to produce various industrial products containing phosphorus, and the suggested process greatly improves the technology for recovering phosphorus-containing materials that are mostly used as fertilizer.


Synthesis of Chemical Precursors via the Catalytic Hydrogenation of 2-Chloropropene

Allyl chloride is a synthetic intermediate that is used as an alkylating agent for pharmaceuticals, and is commonly synthesized at production sites related organochlorides. Allyl chloride is also the raw material that serves as a cross-linking agent for synthetic resins. In that particular synthesis process, however, the by-product 2-chloropropene (2-PEN) is a problem because it essentially has no practical use. In this study, an effective use for 2-PEN was investi-gated in the syntheses of 2-chloropropane (2-PAN) and propylene, which are precursors for various chemical products. To accomplish this, 2-PEN was hydrogenated on commercially available palladium catalysts such as OleMax 201, Ole-Max 301, OleMax 600, and HyFlex 500. The maximum yield of 2-PAN (10.6%) was detected at 348 K, P(H2) = 13.5 kPa and P(2-PEN) = 8.8 kPa, on OleMax 600 (0.5 g), while the maximum yield of propylene (26.0%) was realized under the same reaction conditions, with the exception of using at P(H2) = 7.9 kPa on HyFlex 500 (0.5 g). The selective formation of propylene such as 8.9, 100, and 8.9% for the conversion of 2-PEN, the selectivity of propylene, and the yield of propylene, respectively, were realized on OleMax201. The selective formation of 2-PAN, however, was not observed on all catalysts. Palladium loading strongly influenced the catalytic activity, but had none on either the specific surface area, or basic and acidic properties.

アリルクロライドは，医薬品のアルキル化剤や合成樹脂の架橋剤の原料として使用される合成中間体であり，有機塩素化合物に関連する生産現場で通常に合成される．しかし，合成プロセスによっては，用途の少ない2-クロロプロペン(2-PEN)が副生するため，問題となっている．本研究では，2-PENの有効利用を目的として，2-PENからさまざまな化学製品の前駆体である2-クロロプロパン(2-PAN)とプロピレンの合成を検討した．このために，OleMax 201，Ole-Max 301，OleMax 600，HyFlex 500などの市販のパラジウム触媒を用いて2-PENの接触水素化を検討した．348 K，P(H2) = 13.5 kPaおよびP(2-PEN) = 8.8 kPaの反応条件で， OleMax 600(0.5 g)触媒により，2-PANの最大収率(10.6%)が検出された．一方，プロピレンの最大収率(26.0%)は，P(H2) = 7.9 kPa，HyFlex 500(0.5 g)触媒を用いた以外は同じ反応条件とした場合に検出された． OleMax201では，2-PENの転化率，プロピレンの選択性，およびプロピレンの収率が，それぞれ8.9，100，および8.9%となり，プロピレンの選択的合成が実現された．一方，2-PANの選択的合成はすべての触媒で観察されなかった．パラジウムの担持量が触媒活性に強く影響したが，比表面積，塩基性および酸性は触媒活性に影響しなかった．


Improvement of Propylene Epoxidation Caused by Silver Plasmon Excitation by UV-LED Irradiation on a Sodium-Modified Silver Catalyst Supported on Strontium Carbonate --- Special Issue: Catalytic Epoxidation Reaction

The effect that UV-LED irradiation exerted on a sodium-modified silver catalyst supported on strontium carbonate (Ag-Na/SrCO3) was examined during an epoxidation of propylene to pro-pylene oxide. Based on our previous study, we used Ag(56)-Na(1)/SrCO3 in this study. The num-bers in parentheses refer to the weight percentage of silver and sodium. Although this catalyst system did not contain typical photocatalysts such as titanium oxide or tungsten oxide, UV-LED irradiation of Ag(56)-Na(1)/SrCO3 resulted in an evident improvement in the selectivity and yield of propylene oxide. Such an advantageous effect of UV-LED irradiation could not be dis-cussed based on the bandgap used in photocatalysts, and, therefore, we proposed a mechanism based on the plasmon excitation of silver, which could be accomplished using the irradiation wavelength of UV-LED to produce electrons. Since the lifespan of these electrons is expected to be short, it is difficult to place them into direct contact with the gas phase of oxygen. Once the generated electrons move to SrCO3, however, the lifespan is improved, which could allow suit-able contact with oxygen in the gas phase to form active oxygen. If the oxygen is active for epoxidation as hydrogen peroxide, this could explain the improvement in activity from UV-LED irradiation.

プロピレンのプロピレンオキシドへのエポキシ化に対して炭酸ストロンチウムに担持されたナトリウム修飾銀触媒(Ag-Na/SrCO3)を用いた場合のUV-LED照射も影響を検討した．既報の結果に基づいて，この研究ではAg(56)-Na(1)/SrCO3を使用した．なお，括弧内の数字は，銀とナトリウムの重量パーセントを示す．この触媒には，酸化チタンや酸化タングステンなどの，一般的な光触媒は含まれていないが，Ag(56)-Na(1)/SrCO3触媒にUV-LEDを照射すると，酸化プロピレンの選択性と収率が明らかに向上した．このようなUV-LED照射の加速な効果は，光触媒の議論で汎用されるバンドギャップではできなかったため，UV-LEDの照射波長により発現する銀のプラズモン励起に基づくメカニズムを提案した．UV-LEDを銀のナノ粒子にい照射してプラズモン電子が生成する．これらの電子の寿命は短いと予想されるため，酸素の気相と直接接触させることは困難である．ただし，生成された電子がSrCO3に移動すると，寿命が長くなり，気相中の酸素と適切に接触して活性酸素を形成できるようになる．酸素が過酸化水素のようなエポキシ化に対して有効な活性酸素である場合，本研究で観測されたUV-LED照射による活性の改善を説明できる．


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.


Local Structure Analysis of Active Sites in NiO/γ-Al2O3 Catalyst for Dimethyl Sulfide Decomposition: Sulfurization Behavior of Ni Species Using X-ray Absorption Spectroscopy Analysis

Journal of the Japan Petroleum Institute


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.

Journal of Chemical Engineering of Japan


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．


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．


Carbon Formation and Active Site of Alumina Supported Platinum Catalyst in Steam Methane Reforming Containing Sulfur

抄録 メタン水蒸気改質(SMR)反応を0.1∼2.0 wt% Pt/α-Al2O3触媒を用いて10 ppmのジメチルスルフィド(DMS)を含む条件と含まない条件で行った．DMSを含む場合は初期に劣化が生じるが失活には至らなかった．DMSの供給を停止すると活性は完全に元に戻った．DMSを含むガスの場合は1.0∼2.0 wt% Pt/α-Al2O3触媒上のPtはシンタリングして炭素析出を促進した．このシンタリングと炭素生成挙動はSMR反応と無関係であった．一方，Pt担持量が0.1 wt%だと炭素析出は起こらなかった．これらの結果からPt/α-Al2O3触媒上には三つの活性サイトが形成されたと考えた．一つ目はDMSの影響を受けない活性点，二つ目はDMSにより活性を失うがDMSの供給を停止すると完全に再生する活性点，三つ目はSMRの活性点ではなくシンタリングしたPtがメタン分解を促進して炭素を生成する活性点である．


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.


Alloying Effect of Nickel-Cobalt Based Binary Metal Catalysts Supported on α-Alumina for Ammonia Decomposition


Development of oxide-supported nickel-based catalysts for catalytic decomposition of dimethyl sulfide


Characteristics of H-beta zeolite catalyst for catalytic decomposition of tert-butyl-mercaptane

Journal of the Japan Petroleum Institute


Durability of Ni/TiO2 catalyst containing trace chlorine for CO selective methanation

We investigated the durability of Ni/TiO2 catalyst in CO selective methanation reaction. In the reaction test up to 72 h, trace amounts of chlorine component contained in the catalyst gradually decreased. As a result, the progress of the methanation of CO2 increased, leading to a decrease in the reaction selectivity of the methanation of CO required for the catalyst in the title reaction. By contrast, in the early stage of the reaction in which the elimination of chlorine component was small, it was confirmed that the number of active sites of metallic Ni increased, and the CO methanation activity was improved. Furthermore, it was found that the chlorine component in the catalyst was more remarkably removed by the reaction heat under the methanation reaction atmosphere compared to the other atmospheres. Catalyst durability under the conditions simulating a daily start-up and shut-down operation that repeated a cycle of cooling and heating the temperature of the catalyst layer to room temperature was also evaluated. As a result, we revealed that a trace amount of chlorine component was removed by exposure to condensed water, leading to a decrease in the reaction selectivity of the catalyst.


Degradation factor of Ni/TiO2 catalyst for selective CO methanation: loss of residual Cl on the catalyst


Sponge Ni catalyst with high activity in CO2 methanation

International Journal of Hydrogen Energy


Ammonia synthesis over yttrium-doped barium zirconate and cerate-based perovskite-type oxide supported ruthenium catalysts


Synthesis of tetragonal zirconia in mesoporous silica and its catalytic properties for methanol oxidative decomposition


Ag addition to CuO-ZrO2 catalysts promotes methanol synthesis via CO2 hydrogenation


Sulfur Tolerance of Noble Metal Catalysts for Steam Methane Reforming


Electrochemical synthesis of ammonia using a proton conducting solid electrolyte and nickel cermet electrode


Blue and orange oxygen responsive emissions in the solid state based on copper (I) complexes bearing dodecafluorinated diphosphine and 1, 10-phenanthroline derivative ligands


Electrochemical Synthesis of Ammonia Using Proton Conducting Solid Electrolyte and Ru-doped BaCe0. 9Y0. 1O3-δ Electrode Catalyst


Influence of nitrogen impurity for steam methane reforming over noble metal catalysts


Methanol oxidative decomposition over zirconia supported silver catalyst and its reaction mechanism


Role of trace chlorine in Ni/TiO2 catalyst for CO selective methanation in reformate gas


Decomposition of t-Butanethiol into Hydrogen Sulfide without Hydrogen Addition over HY and H-beta Zeolites

Journal of the Japan Petroleum Institute


Catalytic decomposition of methanethiol to hydrogen sulfide over TiO2


Dimethyl ether steam reforming under daily start-up and shut-down (DSS)-like operation over CuFe2O4 spinel and alumina composite catalysts


A study of various zeolites and CuFe2O4 spinel composite catalysts in steam reforming and hydrolysis of dimethyl ether


Limiting mechanisms in catalytic steam reforming of dimethyl ether


Degradation and regeneration of copper-iron spinel and zeolite composite catalysts in steam reforming of dimethyl ether


Crystal structure and surface species of CuFe2O4 spinel catalysts in steam reforming of dimethyl ether


Catalytic performance enhancement by heat treatment of CuFe2O4 spinel and γ-alumina composite catalysts for steam reforming of dimethyl ether


Effect of Thermal Treatment on Activity and Durability of CuFe2O4Al2O3 Composite Catalysts for Steam Reforming of Dimethyl Ether


Cu-based spinel catalysts CuB2O4 (B= Fe, Mn, Cr, Ga, Al, Fe0. 75Mn0. 25) for steam reforming of dimethyl ether


Transmission electron microscopic observation on reduction process of copperiron spinel catalyst for steam reforming of dimethyl ether


Hydrogen production from dimethyl ether steam reforming over composite catalysts of copper ferrite spinel and alumina


Influence of solidacid catalysts on steam reforming and hydrolysis of dimethyl ether for hydrogen production


Physical mixing of TiO2 with sponge nickel creates new active sites for selective CO methanation