甲烷在MoO_3／HZSM－5分子筛催化剂上的非氧催化转化

研究了反应温度、空速、Ｍｏ担载量和焙烧温度对ＭｏＯ３／ＨＺＳＭ－５催化剂上甲烷的芳构化反应的影响．ＨＺＳＭ－５分子筛的Ｂｒｏｎｓｔｅｄ酸性、孔道结构和Ｍｏ在分子筛中的分布是影响催化性能的重要因素．ＨＺＳＭ－５上Ｍｏ担载量为２～３％时活性最佳，在１０１３Ｋ反应温度下甲烷转化率可达９％，芳烃选择性大于９０％．空速影响的实验表明乙烯是反应的初始产物．在此基础上提出了＂甲烷酸助异裂活化＂的新概念、＂金属钼类碳烯中间物＂的新观点和甲烷芳构化的可能机理．

CATALYTIC CONVERSION OF METHANE OVER MoO_3/HZSM-5 CATALYST UNDER NON-OXIDIZING CONDITION

he effect of Mo loading, calcinating temperature, reaction temperature and space velocity on the catalytic performance of methane aromatization over MoO3/HZSM--5 using a microflow reactor with no oxidants in feed gas has been studied. The Bronsted acidity, the pore channel structure and the location of Mo species in the zeolite are crucial factors for the catalytic performance. It was found that the MoO3/HZSM--5 catalyst with 2% Mo loading showed the best aromatization activity, The methane conversion at 1013 K was 9% with the selectivityfor aromatics higher than 90%. The methane conversion and selectivities of the products are all varied abruptly at Mo loading of 6% which implies that the surface of the MoO,/HZSM-5 zeolite catalyst is affected greatly. The experimental results obtained from the variation of space velocity gave evidence that ethylene is an initial product. Based on these results it is proposed that in which both methane splitting heterogeneously in a solid acid evironment and molybdenum carbene complex as an intermediate play a crucial role.