Effects of acid-modified HBEA zeolites on thiophene acylation and the origin of deactivation of zeolites

• First report on thiophene acylation over acid-modified HBEA zeolite.
• Discussion about origin of deactivation of zeolite on thiophene acylation.
• Use of green renewable technology that can potentially be industrialized.

The liquid phase Friedel–Crafts acylation of thiophene with acetic anhydride over HBEA zeolites modified by hydrochloric, nitric, and acetic acid was investigated in a trickle bed reactor. The catalytic stability of the HBEA zeolite was doubled after treatment with the hydrochloric and nitric acids due to the increase of the ratio of Broensted to Lewis acid sites, the surface area, and the average pore diameter. The deactivated zeolites can be regenerated by calcination in a muffle furnace and the superior reusability of the zeolite HBEA was demonstrated after nine cycles. Moreover, the carbon deposit was proved to be one of the main reasons for the deactivation by using 13C NMR MAS, 27Al NMR MAS, and TGA.

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