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《Comptes Rendus Chimie》2015,18(3):283-292
Here, we present a preliminary study to choose a catalyst with enough catalytic activity at temperatures below 250 °C, in order to study heat transfer in a platelet milli-reactor (PMR) with an infrared camera and a commercial window inserted on the top of our reactor that only withstands a maximal temperature of 250 °C. The higher methane productivity of foam catalysts compared to powder catalysts was revealed. Foam catalysts, all impregnated with the same amount of active phase (Ni + Ru) and with different coatings, were compared to SiC only impregnated with Ni + Ru. The different coatings studied were: carbon nanofibers (CNF), ceria–zirconia (CZ) and the combination of both. Both CNF and CZ washcoats were able to increase the low specific surface area of the SiC foam. Moreover, the presence of ceria–zirconia was proven to be essential for ensuring high methane productivities. The catalyst combining both CNF and CZ showed the best results. 相似文献
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助催化剂Sm2O3对甲烷化镍催化剂的作用 总被引:4,自引:0,他引:4
金属镍催化剂广泛地应用于石油、化肥等工业.八十代初,人们发现稀土氧化物能有效地提高甲烷化镍催化剂性能,并加强了对其添加效应以及作用机理的研究.但此类报道主要集中于La_2O_3、CeO_2等,而对其它稀土氧化物报道甚少.本文采用XRD、TEM、XPS和TPSR等手段,探讨了添加Sm_2O_3对甲烷化镍催化剂的作用,并比较了2种浸渍法所产生的结果. 相似文献
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二氧化碳加氢甲烷化单组分担载型金属催化剂表面漫反射紫外可见光谱研究 总被引:3,自引:0,他引:3
本文通过对二氧化碳加氢甲烷化单组分担载型金属催化剂表面漫反射紫外可见光谱解析,揭示了载体上离子存在形态、活性组分与载体相互作用结果对催化剂活性的影响.制备催化剂焙烧温度、金属担载量和浸渍方式不同,谱信息的变化能为催化剂活性改变提供判据. 相似文献
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采用浸渍法和原位生长水滑石法制备了Ni-Ce/γ-Al2O3和Ni-Ce-LDHs/γ-Al2O3 2种不同类型的催化剂前驱体, 考察了2种前驱体分别经氩-氢等离子体和常规氢热方法还原所得催化剂在CO2甲烷化反应中的活性. 结果表明, 等离子体还原催化剂的低温活性明显高于常规氢热还原催化剂, 主要表现为前者反应启动的临界温度点比后者低20~30 ℃. 采用X射线衍射(XRD)分析、 透射电子显微镜(TEM)、 CO2程序升温脱附(CO2-TPD)以及X射线光电子能谱(XPS)对所得催化剂的形貌和结构进行了表征. 结果表明, 等离子体还原催化剂具有较小的活性组分粒径、 较高的活性组分分散度以及较高的表面碱性, 这些特性有利于催化剂活性位对CO2的化学吸附, 使其在甲烷化反应中表现出较好的低温活性. 相似文献
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Aseries of Ni-W catalysts supported on mesoporous SBA-15 with different Ni:W ratios(NixW/SBA-15, Ni-5%, x=1,10,50) was prepared and fully characterized by powder X-ray diffraction(PXRD), Brunner-Emmet-Teller(BET), transmission electronic microscopy(TEM), H2-temperature programmed reduction(H2-TPR), and X-ray photoelectron spectroscopy(XPS). High-resolution TEM images, XPS measurements, H2-TPR experiments coupled with PXRD results determined the evolution of Ni and W species. It is found that a trace amount of W from H2WO4 can significantly improve Ni dispersion on SBA-15 (Ni50W/SBA-15) with Ni0 andnon-stoichiometric WOx species as small as ca. 3.6 nm. The prepared NixW/SBA-15 was utilized for CO2 hydrogenation, which showed that a higher W content restrained the CO2 hydrogenation while a lower W ratio promoted both conversion rate and selectivity for methane compared with Ni/SBA-15. The Ni50W/SBA-15 catalyst showed the best performance with a 93.3% CO2 conversion rate and 99.7% selectivity for methane at 400 oC under 0.1 MPa and maintained ca. 97% initial performance for 24 h. Tracking product evolution experiments by in-situ Fourier transform infrared spectrascopy(FTIR) indicated that a small amount of W can modify the surface of Ni particles by geometric coverage and electronic modification, which facilitates the adsorption of the CO intermedia and results in the formation of CH4. This work provides a new clue to fabricating efficient CO2 conversion bimetallic materials. 相似文献
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La2O3对Ni-Mo/γ-Al2O3催化剂CO和CO2甲烷化的影响 总被引:10,自引:0,他引:10
采用浸渍法制备了一系列Ni-Mo-La/γ-Al2O3催化剂并测定了催化剂的CO和CO2甲 化活性采用TEM,XPS和CO化学吸附等手段研究了表面性质。结果表明,La2O3的咖入提高了Ni-Mo/γ/Al2O3催化剂的CO和CO2甲烷化活性,增加了催化剂中Ni的分散度,活性表面积及催化剂表面Ni原子的浓度,降低了电子结合能。 相似文献