担载型过渡金属催化剂上CH_4+CO生成CH_3CHO反应的初步研究

利用程序升温脉冲反应、恒温脉冲反应及探针分子的表面反应技术,较系统地考察了担载型过渡金属催化剂上甲烷直接羰基化制乙醛的反应.研究发现,通过采用总反应分解法操作,即首先使甲烷在过渡金属表面分解.然后引入CO使其与甲烷分解产生的表面碳物种反应,实现甲烷的直接羰基化.这种操作能够克服甲烷直接羰基化反应的热力学限制,将总反应转化为两个可在较温和条件下发生的反应,首次实现了CH_4 +CO→CH_3CHO的反应.本文还探讨了不同催化剂上甲烷的吸附条件以及CO与甲烷分解所产生的表面碳物种间的反应行为.结果表明,Pd、Ni基金属催化剂表现出较为优越的催化性能.探针分子CH_3I的表面反应结果显示甲烷分解产生的CH(?)(ad)(x≤3)物种可能是该反应的活性中间体.

Studies on reaction of methane with CO to acetaldehyde on supported transition metal catalysts

Direct carbonylatidn of methane to acetaldehyde on silica-supported transition metal catalysts was tentatively investigated by using temperature programmed pulse reaction (TPPR), constant temperature pulse reaction (CTPR) and surface reaction of probe molecules CH31 (SRPM). An important approach is to split the overall reaction into two reaction steps occurring under moderate conditions. In such a two-step route the thermodynamic limitations can be overcome and the direct carbonylation of methane may be effectively achieved. This reaction is an attractively novel route for utilization of methane. The results show that palladium and nickel catalyst's favor the direct carbonylation of methane. Optimization of this process would result in a new route for effective utilization of methane.