Effect of phosphorus modification and hydrothermal treatment of zeolites on shape-selective methylation of 4-methylbiphenyl

摘要

Shape-selective alkylation of polycyclic hydrocarbons into symmetric intermediates such as 4,4'-dialkylbiphenyl (4,4'-DABP) or 2,6'-dialkylnaphthalene (2,6'-DNA), the important precursors for advanced polymer materials, has been the focus of many recent studies. For the preparation of 4,4'-DABP, alkylation can be carried out using either large alkyl groups like isopropyl or small ones such as methyl group. The results in literature show that it is extremely difficult to obtain shape selectivity to 4,4'-dimethylbiphenyl. Recently, some breakthrough on the methylation of 4-methylbiphenyl with methanol was achieved, in which the selectivity to 4,4'-DMBP can be up to 65% over HZSM-5 modified with inorganic P compound. With the encouraging findings, we further studied shape-selective methylation of 4-MBP with methanol over different HZSM-5 modified with organic and inorganic P, together with hydrothermal treatment.