Catalytic conversion of dimethyl ether to hydrocarbon and effect of isobutane co-feed on catalytic performance were studied over H-MCM-22 and Pt/H-MCM-22. Comparisons of catalyst lifetime, product distribution and overall productivity were elucidated based on dual-cycle mechanism and homologation pathway. Both catalysts were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), nitrogen adsorption, ammonia temperature-programmed desorption (NH3-TPD), pyridine adsorption infrared spectroscopy (Py-IR), solid-state 27Al magic-angle spinning (MAS) NMR. Isobutane co-feed could enhance both olefin-based cycle and aromatic-based cycle and was proved to be effective for product selectivity adjusting and induction period reducing due to the enhanced overall productivity in the early stage but at the cost of shorter lifetime of catalyst. Pt loaded on zeolite provided extra Lewis acidity and lead to faster deactivation, it could also benefit hydrogen transfer, hydrogenolysis and dehydrogenation of alkanes at the same time.%在H-MCM-22和Pt/H-MCM-22分子筛上研究了二甲醚制烃催化性能,及采用异丁烷共进料时整体催化性能的改变,利用双循环机理和同系化反应路径解释了包括催化剂寿命、反应选择性和单位时间产物生成总量等的变化,同时采用X射线衍射、扫描电镜、氮吸附、氨气程序升温脱附、吡啶吸附红外光谱和Al核磁等对催化剂进行了表征.结果表明,共进料异丁烷增强了烯烃循环和芳烃循环,能有效改变二甲醚制烃过程产物选择性并可以缩短反应诱导期,但代价是加快催化剂失活.负载的Pt提供了额外的Lewis酸位,增强了氢转移反应、氢解反应和烷烃脱氢反应,同时缩短了催化剂寿命.
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