The Mechanistic Study of Methane Reforming with Carbon Dioxide on Ni/α-Al2O3
The Mechanistic Study of Methane Reforming with Carbon Dioxide on Ni/α-Al2O3
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Ni/α-Al2O3 二氧化碳重整甲烷机理研究
DOI：
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发表时间：
2002
期刊：
影响因子：
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通讯作者：
V. Korchak
中科院分区：
文献类型：
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作者：
V. Bychkov;O. Krylov;V. Korchak
采用DSC-111差示扫描量热仪和色谱分析系统，研究了氧化还原6 wt % NiO/α-Al2O3与H2、CH4、CO2、O2及其混合物在流动和脉冲状态下的反应。结果表明，在700°С下加氢处理可使NiO部分还原为Ni。甲烷与氧化的Ni/α-Al2O3几乎不发生反应，但与还原的催化剂发生反应，生成H2和表面碳。后者能与Ni/α-Al2O3的晶格氧（慢）和吸附氧（快）反应。二氧化碳还与表面碳反应生成CO（快速），与金属Ni反应生成CO和NiO（缓慢）。因此，甲烷与二氧化碳在Ni/α-Al2O3上的重整主要途径是CH4解离吸附生成表面碳和H2，并与CO2通过逆Boudouard反应生成CO。副路线是甲烷化学吸附产物与催化剂氧的相互作用和CO2在金属镍上的解离吸附。甲烷与二氧化碳重整过程中，表面碳与吸附氧的竞争性反应导致CO2转化率降低。因此，在反应混合物中存在气态氧减慢了甲烷重整（催化剂被氧中毒）。
The reactions of oxidized and reduced 6 wt % NiO/α-Al2O3 with H2, CH4, CO2, O2, and their mixtures are studied in flow and pulse regimes using a setup equipped with a differential scanning calorimeter DSC-111 and a system for chromatographic analysis. It is shown that treatment with hydrogen at 700°С results in the partial reduction of NiO to Ni. Methane practically does not react with oxidized Ni/α-Al2O3 but it does react actively with the reduced catalyst to form H2 and surface carbon. The latter is capable of reacting with lattice oxygen of Ni/α-Al2O3 (slowly) and with adsorbed oxygen (rapidly). Carbon dioxide also reacts with surface carbon to form CO (rapidly) and with metallic Ni to yield CO and NiO (slowly). Thus, the main route of methane reforming with carbon dioxide on Ni/α-Al2O3 is the dissociative adsorption of CH4 to form surface carbon and H2 and the reaction of this carbon with CO2 resulting in the formation of CO by the reverse Boudouard reaction. Side routes are the interaction of the products of methane chemisorption with catalyst oxygen and the dissociative adsorption of CO2 on metallic nickel. A competitive reaction of surface carbon with adsorbed oxygen results in a decrease in the CO2 conversion in methane reforming with carbon dioxide. Therefore, the presence of gaseous oxygen in the reacting mixture decelerates methane reforming (catalyst poisoning by oxygen).