Selective alkylation of phenol and tert-butanol using Zr-containing Beta zeolite

Abstract

The selective alkylation of phenol and tert-butanol is a key challenge in catalyst design. In the present research, Zr-containing Beta zeolites are found to be effective for the selective alkylation of phenol and tert-butanol to effectively produce the desired product 2,4-DTBP. A high conversion of phenol (71%) and selectivity toward 2,4-DTBP (18.5%) can be achieved. Our research reveals that both Brønsted acid sites and Lewis acid sites are active species in the alkylation reaction, but the activity is mainly dominated by the Brønsted acid sites. In addition, the Zr species are primarily distributed in the mesopores of the Beta zeolites, which significantly improves the concentration of Lewis acid sites in the Beta zeolites, while the concentration of Brønsted acid sites is maintained. Our studies demonstrate that 4-TBP is the main product in the alkylation owing to its low steric hindrance, and that 4-TBP exhibits a specific planar geometry that allows it to be adsorbed vertically at the Lewis acid sites located in the mesopores of the Zr-containing Beta zeolites, where it further undergoes over-alkylation reaction, resulting in the formation of the high-added-value product 2,4-DTBP.