Control of Framework Aluminum Distribution in MFI Channels on the Catalytic Performance in Alkylation of Benzene with Methanol
Yilin Wang, Xuan He, Fan Yang, Zhaojie Su, Xuedong Zhu
Abstract
Framework aluminum (AlF) has a correlative relationship with the acid sites in a zeolite, which has been regarded as the key point during the adsorption behavior in alkylation of benzene with methanol. Here, the AlF distribution in HZSM-5 channels was successfully controlled by different pore-filling agents and organic structure-directing agents (OSDAs) in the synthesis step. HZSM-5 samples with AlF preferentially located in the intersections and sinusoidal/straight channels were synthesized using tetrapropylammonium hydroxide and pentaerythritol with Na cations as an OSDA and a pore-filling agent, respectively. Catalytic performances in alkylation of benzene with methanol showed that HZSM-5 zeolite with AlF sitting in the channel and channel intersections generated a coadsorption effect yielding higher benzene conversion, xylene selectivity, and catalytic stability in this reaction. Meanwhile, HZSM-5 zeolite with more AlF located particularly in the sinusoidal channel exhibited better shape selectivity to the para-xylene product.