Advances on biomass pretreatment using ionic liquids: An overview

Petroleum is currently being used as a major source for chemicals, materials, and fuels, but poses major concerns in terms of its future utilisation due to resource limitation, increasing costs and associated environmental issues. An alternative raw material for chemicals and biofuels production is lignocellulosic biomass. The conversion of biomass to biofuels begins with biomass pretreatment in which chemical and/or physical treatments are utilised to remove or weaken the tight linkages among cell-wall components, making biomass easier to degrade. The use of ionic liquids-salts (mixtures of cations and anions that melt below 100 degrees C) has been described as a new potentially viable development in this area due to the increasing interest in the use of such compounds to pretreat lignocellulosic materials and to catalyse the dissolution of cellulose. This manuscript aims to provide an overview on the major representative progress and development of the use of ionic liquids systems for biomass pretreatment and cellulose dissolution. A comparison of the environmental impact of different ionic liquids for the conversion of carbohydrates into useful biofuel intermediates will be described, with their inherent advantages for biomass valorisation processes in terms of unique and tuneable physicochemical properties.