Comparative study on the catalytic performance of zeolite catalysts with different topologies in 1-methylnaphthalene isomerization-transalkylation coupling reaction

The isomerization-transalkylation coupling reaction between 1-methylnaphthalene and 1,3,5-trimethylbenzene was studied over zeolite catalysts to produce 2-methylnaphthalene and dimethylnaphthalene. The catalytic performance of zeolites with MWW, BEA, FAU and MFI topological structure was investigated and the reaction mechanism was discussed. The properties of zeolites were characterized by XRD, N₂ adsorption-desorption, SEM, NH₃-TPD, Py-FTIR and ICP. Compared with MFI zeolite with 10-membered ring channel, MWW, BEA and FAU zeolite with 12-membered ring channel showed better catalytic activity. BEA zeolite exhibited higher selectivity to dimethylnaphthalene, while MWW zeolites showed higher selectivity to 2-methylnaphthalene and the best catalytic stability. As a branch of MWW zeolites, HMCM-22 showed a 1-methylnaphthalene conversion of 70.27% and a 2-methylnaphthalene yield of 66.69%. It was worth noting that a relatively high yield of 2-methylnaphthalene (35.74%) and dimethylnaphthalene (19.00%) were obtained on HMCM-56 at the same time. This research has opened up a promising route using C₁₀ aromatics as raw materials for the preparation of 2,6-dimethylnaphthalene, an important polyester monomer.