CH_4,CO_2催化氧化制合成气催化剂的性能研究

通过对催化剂稳定性的考察并结合表征结果 ,研究了稀土Ce的添加对催化剂稳定性的影响以及催化剂失活的原因 .结果表明 ,稀土Ce在反应过程中存在着部分还原的变价过程 (Ce4 + →Ce3 + -e) ,其结果不但有效地抑制了催化剂的积炭 ,而且也阻滞了γ Al2 O3 在高温、水蒸气存在的反应条件下的相转移过程 ,增强了催化剂抗烧结能力 ,减少了催化剂表面积的损失 ,显著地提高了催化剂的稳定性 .BET ,XPS表征显示 ,经过较长时间反应的Ni Ce/Al2 O3 催化剂 ,其孔径分布的变化以及活性物种Ni和助剂Ce向体相的迁移或流失 ,有可能是造成该类催化剂活性逐步下降的主要原因

A study of catalytic properties for the reaction of catalytic reforming into syngas by methane,carbon dioxide and oxygen

The activity and stability of Ni/Al 2O 3, Ni-Ce/Al 2O 3 catalysts were investigated in a fixed bed continuous-flow quartz reactor.These catalysts before and after reaction were characterized by using BET,TGA,XPS.The results show that during the pretreatment and reaction,Ce 4+ can be reduced to Ce 3+ which has the ability to emerge into Al 2O 3 crystallites and thus improve its thermal stability in the presence of vapor. The Ce additive has also resist carbon deposited on the catalyst and prolong the using time of the catalyst. BET and XPS measurements revealed that the change of pore distribution, the partial loss of Ni and Ce species over the surface of Ni-Ce/Al 2O 3 after using for a long time in this reaction system are responsible for the decrease of the catalyst activity.