甲烷部分氧化制甲醛催化剂MoO_3／SiO_2及MoO-3·MxOy／SiO_2的程序升温还原研究

TPR Study of MoO 3/SiO 2 and MoO 3 M xO y/SiO 2 Catalysts in Partial Oxidation of Methane

利用程序升温还原（ＴＰＲ）方法，研究了甲烷部分氧化制甲醛催化剂ＭｏＯ３／ＳｉＯ２及添加金属氧化物的ＭｏＯ３·ＭｘＯｙ／ＳｉＯ２（Ｍ＝Ｖ、Ｆｅ、Ｎｉ、Ｃｒ、Ｃｕ）催化剂上，活性组分在载体上的分散及ＭｏＯ３与ＭｘＯｙ的相互作用．发现钼含量的提高不利于ＭｏＯ３在ＳｉＯ２上的分散，催化剂表面晶相ＭｏＯ３随钼含量的提高而增多．ＳｉＯ２上担载的活性组分有一个最佳值，对应于最佳催化活性．ＭｏＯ３·ＭｘＯｙ／ＳｉＯ２催化剂中ＭｏＯ３与ＭｘＯｙ发生了不同的相互作用，影响催化剂表面的活性氧物种，导致它们对甲烷氧化活性和甲醛选择性的不同．ＭｏＯ３·Ｖ２Ｏ５／ＳｉＯ２是比较好的催化剂，且Ｖ２Ｏ５添加量有最佳值，对应甲烷氧化制甲醛也有较高的活性和选择性．

The technique of TPR (Temperature Programmed Reduction) has been used to investigate the diffusion of active components on silica and the interaction between MoO 3 and M xO y. Increasing of Mo content has great effect on the diffusion of MoO 3 on SiO 2 and the surface crystal MoO 3 on the catalysts increases with the increasing of Mo content. There is an optimum Mo content on silica which has the best catalytic activity. In MoO 3 M xO y/SiO 2 catalysts, different interaction exist between MoO 3 and M xO y which affects the surface active oxygen species of catalysts and leads to various methane oxidation activity and formaldehyde selectivity. MoO 3 V 2O 5 is found to be the much better catalyst and there is an optimum quantity of V 2O 5 added which gives rise to optimum interaction between MoO 3 and V 2O 5 and higher methane oxidation activity as well as formaldehyde selectivity.