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CO与CO2甲烷化反应研究进展 总被引:4,自引:0,他引:4
介绍了甲烷化反应的催化剂,尤其是Ni基催化剂的研究进展,综述了助剂、载体以及制备方法对甲烷化催化剂催化性能的影响,不同催化剂上CO和CO2甲烷化反应过程的机理。 相似文献
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对国产Ru/Al2O3催化剂研制开发、侧线试验及工业化试用情况进行了探讨,为国产Ru/Al2O3催化剂的推广应用提供了依据. 相似文献
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采用共浸渍法制备了Ni-Mn/Al2O3催化剂,考察了助剂Mn的含量对催化剂结构及浆态床CO甲烷化性能的影响。采用XRD、H2-TPR、BET、TEM、H2-化学吸附等表征对催化剂进行了测试分析,结果表明,Mn助剂的引入能够促进Ni物种在载体表面的分散,减弱Ni物种与载体的相互作用,降低催化剂的还原温度,提高催化剂的比表面积,减小活性金属Ni的晶粒尺寸。随着Mn含量的增加,Ni-Mn/Al2O3催化剂的甲烷化性能先升后降,其中以Mn含量为4%(质量分数)时的催化甲烷化性能最佳,添加过量的Mn导致活性组分Ni被部分覆盖,催化甲烷化性能下降。通过对16Ni4Mn/Al2O3催化剂样品的浆态床反应温度及反应压力的研究发现,当反应温度为280℃、反应压力为1.5 MPa时,催化剂样品16Ni4Mn/Al2O3的CO转化率及CH4选择性分别达到96.2%和88.8%。 相似文献
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利用微反-色谱装置和X-射线衍射法,研究在Ni/Al2O3催化剂中添加稀土氧化物的作用,表明稀土的加入有助于拟制镍晶粒长大、防止金属镍被氧化及NiAl2O4的生成,从而提高催化剂的活性稳定性和抗高温蒸汽氧化的能力。 相似文献
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采用浸渍法制备了添加MgO助剂的Ni/Al2O3催化剂,并用固定床微反装置考察了催化剂在CO甲烷化反应中的催化性能。利用N2物理吸附、X射线衍射、H2程序升温还原、H2脉冲化学吸附和热重等手段对催化剂的结构进行了表征。通过分析样品的还原特性发现,活性组分Ni与Al2O3间的强相互作用会导致催化剂上Ni物种较难还原。MgO的引入可以明显削弱Ni与载体间的强相互作用,提高催化剂的还原度,增加催化剂活性位的数目,同时MgO的存在还能促进Ni颗粒的分散,提高催化剂的抗积碳性能,进而提高催化剂的甲烷化活性。 相似文献
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以经介质阻挡放电等离子体处理的SiO2为载体,用浸渍法制备了Ni/SiO2催化剂,并进行了CO甲烷化反应评价。与载体未经处理的常规Ni/SiO2催化剂相比,载体经处理的催化剂在400℃下的CO与H2转化率均提高了约6%,且在经700℃烧结6 h后,活性仍高于常规催化剂。XRD、TEM和H2-TPR结果表明,载体经处理的催化剂,Ni颗粒粒径更小、粒径分布更集中,Ni与SiO2之间的相互作用更强,证明等离子体处理使SiO2更有利于促进Ni的分散。 相似文献
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Extensive kinetic data for the methanation reaction over a Ni/Al2O3 catalyst were obtained in a specially designed gradientless reactor operating at steady state. The reactor pressure was 101.3 kPa, and three temperatures were used, namely, 503, 513 and 523 K. The following three-parameter phenomenological model based on a proposed Langmuir-Hinshelwood mechanism adequately describes the data: r = L2 K3 K40.5 k5 P0.5H2 Pco/ [1 + K3 (k5 / k6)Pco + K40.5 P0.5H2 ]2 With dissociative adsorption of hydrogen and hydrogen-assisted dissociation of adsorbed carbon monoxide, the postulated mari is the CH surface group, and the rds is the hydrogenation of the surface CH group. 相似文献
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The kinetics of the methanation of carbon dioxide was investigated using an alumina supported Ni-La2O2 catalyst in a differential and integral reactor. In the differential reactor the molar ratio of H2 to CO2 was varied from 0.6 to 30. In the integral reactor the rates were measured with up to 90% conversion. Both reactor tests were carried out at temperatures between 513 and 593 K. The experimental results were described by a Langmuir-Hinshelwood type equation. The kinetics can be explained by assuming equilibrium of dissociative carbon dioxide and hydrogen adsorption, and assuming hydrogenation of surface carbon as the rate determining step. 相似文献
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Jae-Sung Choi Kwang-Ik Moon Young Gul Kim Jae Sung Lee Cheol-Hyun Kim David L. Trimm 《Catalysis Letters》1998,52(1-2):43-47
CO2 reforming of methane was studied over modified Ni/Al2O3 catalysts. The metal modifiers were Co, Cu, Zr, Mn, Mo, Ti, Ag and Sn. Relative to unmodified Ni/Al2O3, catalysts modified with Co, Cu and Zr showed slightly improved activity, while other promoters reduced the activity of CO2 reforming. Mn-promoted catalyst showed a remarkable reduction in coke deposition, while entailing only a small reduction
in catalytic activity compared to unmodified catalyst. The catalysts prepared at high calcination temperatures showed higher
activity than those prepared at low calcination temperature. The Mn-promoted catalyst showed very low coke deposition even
in the absence of diluent gas and the activity changed only slightly during 100 h operation.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
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The effects of hydrogen addition on the formation of hydrogen and carbon from methane decomposition over Ni/Al2O3 were studied. The results show that the added hydrogen in methane greatly affects the methane conversion, hydrogen output rate, and the properties of the carbon deposits on the surface of the Ni/Al2O3. The methane conversion and hydrogen output rate are significantly improved by the addition of hydrogen. As the flowrate of hydrogen increases from 0 to 25 mL/min, the initial activity of Ni/Al2O3 decreases sharply, while the stability increases first and then decreases due to the suppression of hydrogen to CH4 decomposition in the thermodynamics equilibrium. When the addition flowrate of the hydrogen is 15 mL/min, that is, 37.5% of the methane flowrate, a much higher methane conversion and the best stability of Ni/Al2O3 are obtained. The addition of a specific amount of hydrogen benefits the methane decomposition; however, the excessive hydrogen will suppress the decomposition. Most of the carbon that deposits on the surface of Ni/Al2O3 is filamentous carbon when hydrogen is added to the methane, however, encapsulated carbon is mainly produced when no hydrogen is added. In addition, the formation of encapsulated carbon, which deactivates the catalyst, is inhibited by the added hydrogen. 相似文献
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采用共沉淀法、热分解和氢还原等步骤制备了纳米晶载体催化剂Cu-Ni/Al2O3-SiO2,应用X射线衍射、x射线光电子能谱、扫描电镜对催化剂的体相和表面结构进行了测定,采用固定床反应器考察了催化剂对乙醇水蒸气重整制氢反应的催化性能。实验结果表明,5%Cu-Ni/Al2O3-SiO2催化剂对乙醇的低温水蒸气重整反应表现出较高的催化活性,350℃时乙醇的转化率已达到100%。在650℃时氢气的选择性可达78.5%。增加铜含量对增加催化剂的活性没有帮助。 相似文献
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采用并流沉淀法制备了不同配比的ZrO2-Al2O3复合氧化物,并通过浸渍法制备了10% Ni/ZrO2-Al2O3催化剂,考察了复合氧化物载体的水热稳定性及ZrO2与Al2O3的配比对合成气制甲烷Ni基催化剂性能的影响。研究结果表明:ZrO2的添加能在一定程度上抑制Al2O3的水解反应,这可能是ZrO2与Al2O3形成固溶体所致。随着ZrO2含量增加,复合氧化物载体的水热稳定性先降低后升高,当ZrO2与Al2O3质量比为0.24时,载体的水热稳定性最好。不同配比的ZrO2-Al2O3复合氧化物负载Ni基催化剂的稳定性与载体的水热稳定性变化是一致的,说明载体的抗水热能力增强,催化剂结构更稳定,催化剂的活性稳定性相应增加。 相似文献
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羟基新戊醛(HPA)的加氢多采用贵金属和铜系催化剂,为了更好地降低催化剂生产成本和操作成本,分别对比了共沉淀法和浸渍法制备的镍/氧化铝催化剂,并以HPA为原料,在固定床装置上考察了系列催化剂加氢合成新戊二醇(NPG)的催化性能。采用X射线衍射(XRD)、氮气物理吸附(BET)、一氧化碳脉冲吸附等方法进行表征,结果表明,浸渍法制备的20%镍/氧化铝催化剂,比表面积较大,金属分散性好,且催化剂中的镍物种易被还原,其反应性能良好。在相对较温和的反应条件下,即反应温度为103 ℃、反应压力为3 MPa、液时空速为1 h-1、氢醛物质的量比为10时,HPA转化率为100%,NPG选择性为99.3%。在1 000 h的长周期评价过程中,该催化剂保持了较好的活性,具有更好的工业化前景。 相似文献