Catalytic Isomerization of Dimethyltetralin over Silicon- and Boron-Modified H-BEA Zeolites

摘要

Silicon- and Boron-modified H-BEA(Si/Al ratio of 12.5) were prepared by chemical liquid deposition (CLD) of tetraethyl orthosilicate (TEOS) and post-modification method using boric acid, respectively. The catalytic performance of the modified H-BEA catalysts was evaluated for the isomerization of 2,7-dimethyltetralin (DMT) to 2,6-DMT. It was found that the silylation with TEOS passivated preferentially the external acid sites of H-BEA zeolite while the Boron passivated both of the external and internal acid sites. The strong Br?nsted acid sites were responsible for the side reactions such as dealkylation, cracking and transalkylation and can be prevented effectively by the silylation and boronation of BEA zeolite.