Stable Sulfonic MCM-41 Catalyst for Furfural Production from Renewable Resources in a Biphasic System

Abstract

An MCM-41-SO3H catalyst with 14 wt% S was successfully synthesized to be used in furfural production from xylose and hemicellulose in a biphasic n-butanol/water system. The precursor MCM-41 and the acid-functionalized MCM-41-SO3H catalyst were characterized by XRD, FTIR, TEM, N2 physisorption, ICP-MS, TPD-NH3, and XPS. The characterization results indicated that the sulfonic process partially decreased the ordered mesoporous structure and increased the acid strength of the initial MCM-41. The catalytic performance of the xylose conversion was evaluated in a batch-type reactor using different biphasic ecological and renewable n-butanol/water ratios (1:1, 1.5:1, 2:1, and 2.5:1) as dissolvent at 170 °C. The effect of the dissolvent mixture was clearly seen from the larger initial reaction rate and TOF values for the 1.5:1 ratio. This catalytic behavior indicated that a proper proportion of n-butanol/water dissolvent mixture enhanced the solubility of the substrate in the n-butanol-rich mixture and prevented the deactivation of acidic sulfonated surface groups. To achieve transformation of lignocellulosic raw material to value-added products, the MCM-41-SO3H catalyst was also used for the production of furfural. The recycling evaluation tests indicated that for the recovered catalyst submitted to a sulfonation process, the yield of furfural was closer to the fresh catalyst.