富氧条件下Co/MOR 催化剂上甲烷选择催化还原NO

采用浸渍法制备了一系列用于甲烷选择催化还原(CH₄-SCR)氮氧化物的Co/MOR催化剂。采用XRD、BET、TG-MS、H₂-TPR、NH₃-TPD和NO-TPD等手段对催化剂进行表征,并对其在甲烷选择催化还原氮氧化物反应中的活性进行评价。结果表明,钴物种以Co₃O₄尖晶石形态存在于Co/MOR催化剂中;与MOR载体相比,引入钴物种后,催化剂的酸性、氧化还原能力和对NO的吸脱附能力均发生了变化。在甲烷选择催化还原氮氧化物反应中,Co/MOR的催化活性与其氧化还原性能和对NO的吸脱附性能直接相关;其中,Co负载量为10%的Co(10)/MOR催化剂的CH₄-SCR脱硝活性最好,在330℃下NO的转化率达54.2%。     

载体H+含量对CuY甲醇氧化羰基化反应性能影响

通过过量浸渍Cu(NO_3)_2溶液于Y分子筛载体上,制备出Cu负载量为6.4%的CuY催化剂,考察了甲醇氧化羰基化反应的催化性能,并采用X射线衍射(XRD)、H2程序升温还原(H2-TPR)、透射电子显微镜(TEM)和NH3程序升温脱附(NH3-TPD)等手段对催化剂表面微观结构进行了表征。研究表明,随Y分子筛载体H+含量的增加,可使更多Cu物种落位于分子筛微孔笼结构中,且高度分散,而笼内未交换的Na+能进一步促进铜物种更多落位于载体超笼结构中,形成更多甲醇氧化羰基化反应的Cu+活性中心。同时随铜物种引入,催化剂中产生了明显的中强酸,酸量随落位于载体笼结构中的Cu物种的增加而增加,催化剂总酸量随之增加,导致甲醇氧化羰基化产物分布发生改变,碳酸二甲酯(DMC)选择性明显降低。对比等体积浸渍法制备的92.3%的高DMC选择性CuY催化剂,以不含H+的NaY分子筛为载体,过量浸渍法制备的CuY催化剂酸量少、Cu物种活性中心多,在保持82.4%的高DMC选择性时,其DMC的时空收率(STY)也高达109.1mg·g~(-1)·h-1。     

Kinetic behaviour of commercial catalysts for methane reforming in ethanol steam reforming process

Ethanol steam reforming has been studied in a fluidized bed （in order to ensure bed isothermicity） on commercial catalysts for methane reforming. The results allow analyzing the effect of temperature （in 300-700℃ range）, and both metal and support nature on the reaction indices （ethanol conversion, yields and selectivities to H2 and byproducts （CO2, CO, CH4 and C2H4O））. Special attention has been paid to catalysts＇ stability by comparing the evolution of the reaction indices with time on stream at 500°C （minimum CO formation） and 700℃ （minimum deactivation by coke deposition）. Although they provide a slightly lower H2 yield, the results evidence a good behaviour of Ni based catalysts, indicating that they are an interesting alternative of more expensive Rh based ones.     

甲醇水蒸气重整制氢Pd/ZnO催化剂的研究

采用并流共沉淀法制备Pd／ZnO甲醇水蒸气重整制氢催化剂,考察了Pd的质量分数和还原温度对催化剂性能的影响。结果表明,当Pd质量分数为15．9％,还原温度为573K时,催化剂有较好的甲醇转化率及二氧化碳选择性。TPR结果表明,PdO在室温下被还原为金属Pd,在440K开始有部分ZnO被还原。XRD分析结果表明,PdZn合金是甲醇水蒸气重整反应的活性中心;在21．9％Pd／ZnO催化剂上出现了Pd2Zn合金相,导致催化剂的活性下降;反应过程中还原催化剂形成PdZn合金,其活性不如相同条件下纯氢还原的。15．9％Pd／ZnO催化剂及工业铜基催化剂的初始稳定性结果显示,在8h内,15．9％Pd／ZnO催化剂上甲醇转化率保持在66％以上,而铜基催化剂的活性下降了14．4％。     

Rh/ZnO-Al2O3催化剂用于巴豆醛选择性加氢（英文）

Gas phase hydrogenation of crotonaldehyde was performed over 1 wt% Rh/ZnO-Al2O3 catalysts with various Zn/Rh atomic ratios. Monometallic Rh/Al2O3 was also prepared for comparison. The samples were prepared by the successive impregnation of Al2O3 with chlo-ride precursors of zinc and rhodium. The solids have been characterized by H2 chemisorption,temperature-programmed reduction,scanning electron microscopy,and cyclohexane dehydrogenation. Their catalytic behaviour in the gas phase crotonaldehyde hydrogenation reaction after reduction treatment in flowing hydrogen at 723 K was investigated. The relationship between catalytic activity,selectivity for crotyl alcohol,and physicochemical properties of the catalysts was examined. Results obtained showed that the presence of Zn clearly promotes the hydrogenation of the carbonyl bond. The catalyst with Zn/Rh atomic ratio of 5 displayed good catalytic stability and the highest selectivity for crotyl alcohol(70%) along with alloy formation.     

溶胶凝胶法制备甲醇裂解铜系催化剂

甲醇具有能量密度高、易于储存运输及价格低廉等优点,以甲醇作为氢气载体裂解制H2,可以解决氢气难以储存运输的困难。用于该反应的催化剂较多,铜系催化剂以其价格便宜、毒性小等特点而受到研究者的广泛关注。但是该催化剂在低温下活性不高。本文用溶胶一凝胶法制备技术研制了一系列加助剂的铜系催化剂,进行热重和TPR表征,讨论其在甲醇裂解制氢模型反应中的应用。     

沸石分子筛催化剂上萘的择形异丙基化反应性能

 研究了HY,Hβ,HM和HZSM－5沸石分子筛对萘择形异丙基化反应的催化性能．结果发现,这些沸石分子筛的活性顺序为HY＞Hβ＞HM＞HZSM－5,对2,6－二异丙基萘的选择性顺序为HM＞Hβ＞HY．除沸石分子筛的酸量与酸分布外,其孔道结构与大小是影响萘异丙基化反应的主要因素．脱铝能选择性地降低沸石外表面的酸性,且对沸石的催化性能有较大影响．常压水蒸气脱铝结合强酸再处理有利于催化剂催化性能的提高．提高反应温度有利于萘的转化,但温度过高会引发许多副反应,适宜的反应温度约为523K．反应时间对产物分布的影响不明显．异丙醇／萘摩尔比应小于2．     

负载Ni催化剂上低温甘油蒸汽重整制氢

采用等体积浸渍法制备了Al₂O₃、CeO₂、TiO₂及MgO负载Ni催化剂,考察了它们对甘油蒸汽重整制氢反应的催化性能。采用X射线衍射、N₂吸附、透射电镜及H₂程序升温还原等方法对催化剂进行了表征。结果表明,载体对Ni催化剂的活性有显著影响。在400 ℃下Ni/CeO₂的催化活性明显好于其他催化剂,活性次序为Ni/CeO₂> Ni/Al₂O₃ > Ni/TiO₂ ~ Ni/MgO。Ni/CeO₂也具有好的稳定性,反应20 h未见活性下降,甘油转化率70%,氢气收率69.2%。这与CeO₂的本性及其与活性组分的相互作用有关。Al₂O₃具有较大的比表面积与孔体积,有利于CO吸附及甲烷化反应的进行,使得Ni/Al₂O₃催化剂在较高温度下具有很高的甘油转化率85.7%,但H₂选择性较差。由于MgO载体与活性组分强的相互作用而生成NiMgO₂固溶体,导致Ni/MgO低温活性差。     

Effect of the calcination temperature on the properties of Fe2O3/SiO2 catalysts for oxidation of hydrogen sulfide

The effect of the calcination temperature on the properties of supported iron oxide catalysts for hydrogen sulfide oxidation prepared by impregnation of silica with iron(III) nitrate has been studied. An increase in the calcination temperature was found to diminish the catalytic activity of the Fe₂O₃/SiO₂ catalysts in hydrogen sulfide oxidation. This behavior can be explained by the agglomeration of iron oxide particles and by a decrease in the surface concentration of active sites. It has been shown that an increase in the calcination temperature makes the catalyst more stable towards the sulfidation of the active component (Fe₂O₃) to the iron disulfide phase.     

A review on the zeolite-like nano spaces formed by the tectonics of organic compounds

Studies on the organic molecular sieves with organic and/or organometallic molecules as the tectons are reviewed. Research works in Japan for the synthesis and application of this organic three-dimensional tectonics are emerging. Osaka Gas announced development of a natural gas reservoir (for NG-fueled cars) based on the adsorbent of the Cu-dicarboxylate. Catalytic application is also started in Japan.     

Shape‐Selective Interception by Hydrocarbons of the O2‐Derived Oxidant of a Biomimetic Nonheme Iron Complex

Picky ferryl : The complex [Fe(Tp)(BF)] (Tp=hydrotris(3,5‐diphenylpyrazolyl)borate; BF=benzoylformate) reacts with O₂ to generate an oxidant (see picture; O red, pink; Fe yellow; N blue; C gray; H white) that oxidizes added hydrocarbons shape‐selectively. Discrimination derives from a cleft formed by two phenyl groups of the Tp ligand, favoring oblate spheroidal substrates.

     

硅烷化改性对纳米ZSM-5甲醇制汽油催化剂性能的影响

对比了水热处理后微米ZSM-5和纳米ZSM-5分子筛的物化性质和催化甲醇制汽油(MTG)的反应性能,发现采用纳米ZSM-5分子筛催化剂能得到较高的汽油收率和较长的寿命,但汽油中均四甲苯含量较高.对纳米ZSM-5分子筛进行硅烷化处理,利用低温N_2吸附-脱附、X射线衍射(XRD)、氨气程序升温脱附(NH_3-TPD)对改性前后的样品进行表征.在温度380℃、压力2.0 MPa、空速3.0 h~(-1)的反应条件下进行MTG反应,对硅烷化改性后的催化剂进行评价.结果表明,负载SiO_2后催化剂的强酸中心降低,比表面积和孔容降低.纳米ZSM-5分子筛合适的SiO_2负载量为2%,硅改性后用于MTG反应,催化剂的寿命和汽油收率分别由改性前的144 h和33.6%显著增加到180 h和34.4%.当SiO_2负载量继续增加时,催化剂寿命和汽油收率逐渐降低.另外,随SiO_2负载量的增加,其催化MTG所得汽油产品中的异构烷烃和芳烃含量降低,烯烃和正构烷烃含量增加,均四甲苯含量显著降低,改善了油品质量.     

草酸处理对丙烷氨氧化催化剂Sb-V-O结构和催化性能的影响

以不同量的草酸处理钒的起始原料,采用共沉淀法制备了VSb3混合氧化物催化剂,运用N2低温吸附、X射线衍射、X射线光电子能谱和H2程序升温还原等方法对催化剂进行了表征,并考察了其在丙烷氨氧化反应中的催化性能.结果表明,草酸的处理可使所得样品中V处于较低的价态,从而有利于活性相SbVO4的生成.当草酸/V(摩尔比)为3时,所制VSb3混合氧化物中存在较多的活性相SbVO4,且其表面具有适量Sb和V的分布,使催化剂具有良好的氧化/还原性能平衡,因而在丙烷氨氧化反应中表现出更高的活性和丙烯腈选择性.     

用于NH3选择性催化还原NO的非钒基催化剂研究进展

NH3选择性催化还原NO (NH3-SCR)技术在燃煤电厂烟气脱硝过程中有着多年的工业应用经验,也是最有望实际应用于柴油车尾气NOx催化去除的技术之一.鉴于目前工业化应用的V2O5-WO3 (MoO3)/TiO2催化剂体系应用于柴油车尾气净化仍存在着诸多问题,开发新型、高效、稳定且环境友好的非钒基NH3-SCR催化剂体...     

Development of high performance Cu/ZnO-based catalysts for methanol synthesis and the water-gas shift reaction

Our groups studies on Cu/ZnO-based catalysts for methanol synthesis via hydrogenation of CO₂ and for the water-gas shift reaction are reviewed. Effects of ZnO contained in supported Cu-based catalysts on their activities for several reactions were investigated. The addition of ZnO to Cu-based catalyst supported on Al₂O₃, ZrO₂ or SiO₂ improved its specific activity for methanol synthesis and the reverse water-gas shift reaction, but did not improve its specific activity for methanol steam reforming and the water-gas shift reaction. Methanol synthesis from CO₂ and H₂ over Cu/ZnO-based catalysts was extensively studied under a joint research project between National Institute for Resources and Environment (NIRE; one of the former research institutes reorganized to AIST) and Research Institute of Innovative Technology for the Earth (RITE). It was suggested that methanol should be produced via the hydrogenation of CO₂, but not via the hydrogenation of CO, and that H₂O produced along with methanol should greatly suppress methanol synthesis. The Cu/ZnO-based multicomponent catalysts such as Cu/ZnO/ZrO₂/Al₂O₃ and Cu/ZnO/ZrO₂/Al₂O₃/Ga₂O₃ were highly active for methanol synthesis from CO₂ and H₂. The addition of a small amount of colloidal silica to the multicomponent catalysts greatly improved their long-term stability during methanol synthesis from CO₂ and H₂. The purity of the crude methanol produced in a bench plant was 99.9 wt% and higher than that of the crude methanol from a commercial methanol synthesis from syngas. The water-gas shift reaction over Cu/ZnO-based catalysts was also studied. The activity of Cu/ZnO/ZrO₂/Al₂O₃ catalyst for the water-gas shift reaction at 523 K was less affected by the pre-treatments such as calcination and treatment in H₂ at high temperatures than that of the Cu/ZnO/Al₂O₃ catalyst. Accordingly, the Cu/ZnO/ZrO₂/Al₂O₃ catalyst was considered to be more suitable for practical use for the water-gas shift reaction. The Cu/ZnO/ZrO₂/Al₂O₃ catalyst was also highly active for the water-gas shift reaction at 673 K. Furthermore, a two-stage reaction system composed of the first reaction zone for the water-gas shift reaction at 673 K and the second reaction zone for the reaction at 523 K was found to be more efficient than a one-stage reaction system. The addition of a small amount of colloidal silica to a Cu/ZnO-based catalyst greatly improved its long-term stability in the water-gas shift reaction in a similar manner as in methanol synthesis from CO₂ and H₂.     

整体式 Cu-ZSM-5 催化剂上 NH3 选择性催化还原 NO 活性

 采用浸渍法制备了一系列不同 Cu 含量的 Cu-ZSM-5 催化剂, 并用于 NH₃ 选择性催化还原 (SCR)NO 反应. 结果表明, 当 Cu 含量为 8%时, Cu-ZSM-5 催化剂的活性最高; 当空速为 30 000 h^–1. , 在 198~440 ^oC 反应时 NO 转化率均高于 80%, 最高可达 97%, 且空速的影响较小. 经快速水热老化后, 该催化剂活性明显优于商用 V 基催化剂. H₂O 和 SO₂ 对 Cu-ZSM-5 催化剂的 SCR 活性有所影响, 但可明显恢复. X 射线衍射和 NH3 程序升温脱附结果表明, 当 Cu-ZSM-5 中 Cu 含量为 8% 时, 进入 ZSM-5 中阳离子位的 Cu 较多, 催化剂的活性较高, 且其表面具有较多的酸中心和酸量, 从而有利于 SCR 反应.     

Study on the Precursor Phase Composition of Fused Iron Catalyst for Fischer-Tropsch Synthesis

The effect of the precursor composition of fused iron catalyst on the performance of Fischer-Tropsch synthesis was investigated. XRD, BET and CO2 adsorption experiments were carried out to provide better insight into the relationship therein. The results showed that the selectivity of C5＋ hydrocarbon products was dependent on the mole ratio of Fe^2＋/Fe^3＋, which was represented by a hump-shaped curve. Catalysts with precursors containing Fe3O4 phase favored the magnetite spinal formation during F-T reaction, while Fe（1-x）O-based catalysts were more likely to favor the formation and growth of the iron carbide crystals.     

铈源对甲醇水蒸气重整制氢CuO/CeO2催化剂的影响

采用沉淀法合成了CeO_2载体,再经浸渍法负载活性组分得到CuO/CeO_2催化材料,探究了铈源(Ce(NO_3)_3·6H_2O、Ce Cl_3·6H_2O、Ce(NH_4)_2(NO_3)_6、Ce(SO_4)_2·4H_2O)对CuO/CeO_2催化性能的影响。通过采用XRD、SEM、N_2O滴定、BET和H_2-TPR等表征手段对催化材料的结构和性质研究发现,四种铈源合成的CuO/CeO_2催化材料在Cu比表面积、还原性能以及活性组分和载体间的相互作用方面存在着明显差别。其中,由Ce(NO_3)_3·6H_2O合成的CuO/CeO_2催化材料的Cu比表面积较大,CuO还原温度较低,CeO_2载体与CuO之间相互作用较强,在甲醇水蒸气重整反应过程中,表现出较佳的催化活性,在反应温度为553 K,水醇比n(H_2O)/n(MeOH)为1.2,甲醇水蒸气气体空速(GHSV)为1760 h~(-1)时,甲醇的转化率为100%,重整气中CO摩尔含量为0.84%。     

焙烧温度对甲醇水蒸气重整制氢Ce/Cu/Zn-Al水滑石衍生催化剂的影响

采用原位合成法在γ-Al_2O_3载体表面上合成了Zn-Al水滑石,再采用顺序浸渍法制备了一系列Ce/Cu/Zn-Al催化剂,并采用XRD、BET、H_2-TPR和XPS等手段对催化剂进行了表征,考察了焙烧温度对Ce/Cu/Zn-Al催化剂表面结构及其催化甲醇水蒸气重整制氢性能的影响。结果表明,焙烧温度主要影响了催化剂的Cu比表面积、表面氧空穴含量和Cu-Ce间相互作用。当焙烧温度为500℃时,催化剂Cu的比表面积较大,表面氧空穴含量较多,Cu-Ce间相互作用较强,因此,催化甲醇水蒸气重整制氢活性较好。当焙烧温度升高到700℃时,Cu物种主要以稳定的CuAl_2O_4尖晶石形式存在,不利于甲醇水蒸气重整制氢反应的进行,因此,催化活性较差。