Methylation of 2-methylnaphthalene with methanol to 2,6-dimethylnaphthalene over HZSM-5 modified by NH_4F and SrO  

作　　者：Chen Zhang Xin Wen Guo Ya Nan Wang Xiang Sheng Wang Chun Shan Song 

机构地区：[1]State Key Laboratory of Fine Chemicals, Dalian University of Technology, Dalian 116012, China [2]Clean Fuels and Catalysis Program, The Energy Institute and Department of Energy ＆ Geo-Environmental Engineering, The Penmylvania State University, 209 Academic Projects Building, University Park, PA 16802, USA

出　　处：《Chinese Chemical Letters》2007年第10期1281-1284,共4页中国化学快报（英文版）

摘　　要：The methylation of 2-methylnaphthalene （2-MN） into 2,6-dimethylnaphthalene （2,6-DMN） was investigated over the solid acid catalysts. The results show that HZSM-5 modified by NH4F has better catalytic performance than parent HZSM-5 due to the decrease in the acidity. When NH4F/HZSM-5 is further modified by SrO, its catalytic activity decreases due to the decrease in the total acid amount and acidic strength. As a result, the comprehensive modification of NH4F and SrO leads to the inere, ase in the 2,6- DMN selectivity （2,6-DMN to DMN）, up to 64.8% when 2-MN conversion is 10%. We calculated the ESP charge by density functional theory and the results show that the 6-position in 2-MN has higher ESP charge value than 7-position. The formation of 2,6-DMN is favored energetically as compared to that for 2,7-DMN. This suggests during the alkylation of 2-MN inside the ZSM-5 channel, the formation of 2,6-DMN is favored electronically than that of 2,7-DMN. Hence, lowering the acidity of catalyst is a key factor to obtain high selectivity of 2,6-DMN.The methylation of 2-methylnaphthalene （2-MN） into 2,6-dimethylnaphthalene （2,6-DMN） was investigated over the solid acid catalysts. The results show that HZSM-5 modified by NH4F has better catalytic performance than parent HZSM-5 due to the decrease in the acidity. When NH4F/HZSM-5 is further modified by SrO, its catalytic activity decreases due to the decrease in the total acid amount and acidic strength. As a result, the comprehensive modification of NH4F and SrO leads to the inere, ase in the 2,6- DMN selectivity （2,6-DMN to DMN）, up to 64.8% when 2-MN conversion is 10%. We calculated the ESP charge by density functional theory and the results show that the 6-position in 2-MN has higher ESP charge value than 7-position. The formation of 2,6-DMN is favored energetically as compared to that for 2,7-DMN. This suggests during the alkylation of 2-MN inside the ZSM-5 channel, the formation of 2,6-DMN is favored electronically than that of 2,7-DMN. Hence, lowering the acidity of catalyst is a key factor to obtain high selectivity of 2,6-DMN.

关 键 词：2 6-DMN  Modification Selectivity ESP charge 

分 类 号：O62[理学—有机化学]