Catalytic Study Of Methanol Aromatic Alkylation Reaction Over A Microporous/Mesoporous MCM-41/Y Molecular

Nowadays, aromatic alkylation attracted more and more attention in catalysis. The alkylation catalysts were mostly modified zeolites, and the reaction mechanism was electrophilic addition. With the development of C1chemistry, methanol overcapacity with low price, so synthesis these important chemical raw materials and intermediates directly from methanol aromatic alkylation reaction can not only consume methanol but help to optimize aromatics resources. The reaction between methanol and methyl naphthalene2,6-dimethylnaphthalene (2,6-DMN) was studied over microporous/mesoporous zeolites. Meanwhile, the catalysts were characterized by NH3-TPD、Py-IR and XRD to explore the advantages of the catalyst. Concluded the unique advantages of MCM-41/Y.MCM-41/Y composite catalyst was obtained by hydrothermal method, microporous and mesoporous were both existed in the catalyst system. The catalytic performance of MCM-41/Y was evaluated by aromatics alkylation reaction in comparison with HZSM-5and HY catalyst. Pyridine-IR spectrum showed that HZSM-5had both L-acid and B-acid sites, while HY only had B acid sites observed. MCM-41/Y is similar to HY, but had lower acid strength. The initial activity for methanol and2-MN of these three catalysts decreased as followed:MCM-41/Y>HY>HZSM-5. Moreover, MCM-41/Y had the highest selectivity for DMN compared with HZSM-5and HY. The lower activity and selectivity of HZSM-5and HY were due to the strong acidic surface of both catalysts over consumed methanol, meanwhile, TMN formed as by-product by further transformation of DMN.The desiliconization effect of aromatic alkylation was studied over desiliconization zeolites(ZM, YM and βM).The results showed that the acidity strength, acidity quantities were all decreased especially for B-acidity. In case of methylation of2-MN with methanol, when zeolites (HZSM-5, HY and Hβ) were desilicated, the selectivity of sym-TMB,DMN and2,6-DMN were enhanced.The influence of HZSM-5treated with the TEOS as well as the cladding type of molecular sieve MCM-41/Y towards the methyl naphthalene and methanol alkylation are inverstigated, and the results showed that the conversion of2-MN with MCM-41/Y as catalyst is higher, this is because after treated with the TEOS, the catalyst has smaller pore size, which, is not conducive to the diffusion.However, after treated with the TEOS, HZSM-5have better shape selectivity towards2,6-DMN.