处理条件对Mo/HZSM-5催化剂结构及性能的影响

使用付立叶变换红外光谱和固体高分辨核磁技术，考察了在不同处理条件下，甲烷无氧芳构化催化剂Ｍｏ／ＨＺＳＭ５分子筛骨架结构的变化情况．结果显示，较高的焙烧温度和较高的预处理温度，都会造成催化剂中担载的钼物种对分子筛骨架铝的严重抽提，特别是在钼物种含量较高时，这种情况更明显．以不同担体及不同钼物种构成的前驱态催化剂的催化反应评价结果表明，以微晶状态存在的ＭｏＯ３和与担体间以相对较弱作用力存在的高分散钼物种，在反应过程中被活化成具有催化活性钼物种的几率更大；而晶相状态的Ａｌ２（ＭｏＯ４）３以及与载体间存在较强相互作用力的钼物种，在甲烷无氧芳构化过程中不起主要催化活性作用．计算得出，甲烷无氧脱氢芳构化反应的表观活化能为８９．８ｋＪ／ｍｏｌ．

Influence of Pretreatment Conditions on the Structure and Catalytic Performance of Mo/HZSM 5 Catalysts for Methane Activation without Oxygen

By combining the catalytic performance with the results of FT IR and 27 Al MAS NMR, it is concluded that calcination and pretreatment temperatures have obvious effects on the structure of Mo/HZSM 5. Increasing calcination and pretreatment temperatures causes stronger interaction between Mo species and the framework aluminum in HZSM 5, a new Al 2(MoO 4) 3 crystalline phase is formed, and methane dehydrogenation and aromatization activity drops dramatically. The formation of Al 2(MoO 4) 3 crystallites is a main detrimental factor for methane dehydrogenation and aromatization on Mo/HZSM 5 catalysts.