A kinetic study on microwave-assisted conversion of cellulose and lignocellulosic waste into hydroxymethylfurfural/furfural

Native cellulose, lignocellulosic materials from Brazil (carnauba palm leaves and macauba pulp and shell) and pine nut shell from Spain have been studied as substrates for the production of HMF and furfural in a conventional microwave oven. In order to promote the dissolution of native cellulose, several ionic liquids, catalysts, organic solvents and water doses have been assessed. The most suitable mixture (5 mL of choline chloride/oxalic acid, 2 mL of sulfolane, 2 mL of water, 0.02 g of TiO2 and 0.1 g of substrate) has been chosen to conduct kinetic studies at different reaction times (5-60 min) and various temperatures (120-200 degrees C) and to evaluate the best conditions for HMF + furfural production according to Seaman's model. The best production yields of HMF + furfural have been attained for native cellulose, with a yield of 53.24% when an ultrasonic pretreatment was used prior to a microwave treatment with stirring. (C) 2014 Elsevier Ltd. All rights reserved.