Selective Production of Biobased Phenol from Lignocellulose-Derived Alkylmethoxyphenols

Abstract

Lignocellulosic biomass is the only renewable source of carbon for the chemical industry. Alkylmethoxyphenols can be obtained in good yield from woody biomass by reductive fractionation, but these compounds are of limited value for large-scale applications. We present a method to convert lignocellulose-derived alkylmethoxyphenols to phenol that can be easily integrated in the petrochemical industry. The underlying chemistry combines demethoxylation catalyzed by a titania-supported gold nanoparticle catalyst and transalkylation of alkyl groups to a low-value benzene-rich stream promoted by HZSM-5 zeolite. In this way, phenol can be obtained in good yield, and benzene can be upgraded to more valuable propylbenzene, cumene, and toluene. We demonstrate that intimate contact between the two catalyst functions is crucial to transferring the methyl groups from the methoxy functionality to benzene instead of phenol. In a mixed-bed configuration, we achieved a yield of 60% phenol and 15% cresol from 4-propylguaiacol in a continuous one-step reaction at 350 °C at a weight hourly space velocity of ∼40 h–1.