Ni/CeO_2-Al_2O_3复合氧化物催化甲烷部分氧化制合成气的性能

Catalytic Performance of Ni/CeO_2-Al_2O_3 Composite Oxide in Partial Oxidation of Methane to Produce Synthesis Gas

采用柠檬酸络合法一步制备了Ni/CeO2-Al2O3复合氧化物催化剂。利用N2物理吸附、XRD、H2-TPR和SEM手段对催化剂进行了表征。考察了还原条件对该复合氧化物在甲烷催化部分氧化(POM)制合成气的催化性能的影响,进一步考察了原料气配比(V(CH4)/V(O2))、反应空速和反应温度对Ni/CeO2-Al2O3催化POM反应性能的影响。结果表明,Ni/CeO2-Al2O3复合氧化物的热稳定性好,比表面积较大(108m2/g),其中的NiO容易被还原。在700℃、纯H2气氛下还原后的Ni/CeO2-Al2O3在POM反应中表现出最好的催化性能。最佳反应条件为V(CH4)/V(O2)=2、GHSV=12000mL/(h·g)、反应温度750℃。在该反应条件下,POM反应的CH4转化率大于85%,CO选择性达到85%,H2选择性大于94%。

A Ni/CeO2-Al2O3 composite oxide catalyst was prepared by a single-step citric acid complexation method.The produced composite oxide was characterized by means of N2 physical adsorption,XRD, H2-TPR and SEM. The effects of reduction conditions on the catalytic performance of the composite oxide catalyst in catalytic partial oxidation of methane（POM）to synthesis gas were investigated.The investigation in the influences of V（CH4）/V（O2）,gas hourly space velocity and reaction temperature on the catalytic performance of Ni/CeO2-Al2O3 was carried out.The results showed that the prepared Ni/CeO2-Al2O3 composite oxide exhibited high thermal stability and large specific surface area（108m2/g）.Moreover,NiO in the composite oxide was easy to be reduced.The Ni/CeO2-Al2O3 reduced by temperature-program method at 700℃ in pure H2 exhibited the best catalytic performance in POM reaction.The optimum POM reaction conditions were as following,V（CH4）/V（O2）=2,GHSV=12000 mL/（h·g）,T=750℃,under which Ni/CeO2-Al2O3 exhibited high catalytic activity and high selectivity to products with the methane conversion of larger than 85% and the selectivities of 85%for CO and 94%for H2.