Tailoring porosity and acidity of In-Situ Mg-B-Dual-Modified ZSM-5 zeolite for benzene alkylation with methanol to toluene and xylene

High-efficiency production of toluene and xylene from benzene-methanol alkylation is a potential way to optimize the resource structure between petrochemical and coal chemical industry. Herein, the porosity and acidity of ZSM-5 zeolite have been successfully tailored by in-situ Mg- and B-isomorphous substitution. UV-VIS-DRS, FT-IR, NH3-TPD and Py-IR characterizations unveiled that B and Mg isomorphous substitution in the framework of ZSM-5 and the detachment of Mg from the framework during calcination can enable the abundant weak Br & oslash;nsted/Lewis acidic sites and the reduction of strong acidic sites. Thanks to the appropriate acidic density, types and strength to inhibit the alkylation of benzene and ethylene, as well as large mesopore to facilitate the mass transfer, the optimized 4 %Mg@B2-HZM-5 exhibits the excellent alkylation performance of benzene and methanol with a XB of 50.5 %, ST of 52.2 %, SC8 of 36.8 %, SC9+ of 11.0 %, YEBinC8 of 5.3 %, and robust stability (240 h) at high WHSV (20 h- 1). The possible mechanism on 4 %Mg@B2-HZM-5 for benzene alkylation with methanol was also further discussed. This work provides an efficient strategy to modulate the porosity and acidity via B and Mg isomorphous dual substitution to achieve an improved catalytic performance in benzene alkylation with methanol.