Direct conversion of cellulose and raw biomass to acetonitrile by catalytic fast pyrolysis in ammonia

Abstract

Selective conversion of biomass to value-added chemicals provides a green and sustainable route for the current chemical industry which relies mainly on fossil resources. Acetonitrile (CH₃CN) is a widely used solvent and important intermediate in organic and inorganic syntheses. In this study, we show that acetonitrile can be directly produced within seconds from biomass (including cellulose, xylose, lignin, bagasse, rice husk and birch) in ammonia (NH₃) over metal oxide modified zeolite catalysts via a coupled process of catalytic fast pyrolysis and ammonization (CFP-A). Catalyzed by CoOx/HZSM-5, acetonitrile is the dominant product from cellulose, with a carbon yield of 32.5% and a selectivity of 84.6% in bio-oil. Both experimental investigation and density functional theory (DFT) calculations on the formation pathways of acetonitrile indicated that they are promoted mainly by the (–Co–O–Si–) sites of the CoOx/HZSM-5 catalyst; cellulose selectively pyrolyzed to C2 oxygenated compounds such as acetaldehyde and acetic acid, which further reacted with ammonia to form imine and amide, and then generated acetonitrile either through dehydrogenation or dehydration. This efficient process provides a promising approach for improved biomass valorization.