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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 NH_4F has better catalytic performance than parent HZSM-5 due to the decrease in the acidity.When NH_4F/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 NH_4F and SrO leads to the increase 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 NH_4F has better catalytic performance than parent HZSM- 5 due to the decrease in the acidity. WHEN NH_4F / 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 NH_4F and SrO leads to the increase in 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 .ence, lowering the acidity of catalyst is a key fa ctor to obtain high selectivity of 2,6-DMN.