HIPEs template: Towards the synthesis of polymeric catalysts with adjustable porous structure, acid–base strength and wettability for biomass energy conversation

Abstract

Due to its widely available, inexpensive, renewable and carbon–neutral properties, biomass of cellulose is considered to be the most promising candidate to produce 5-hydroxymethylfurfural (HMF). In this work, high internal phase emulsions (HIPEs) templating methodology, subsequent ion-exchange, and the surface grafting technique are combined to synthesize macroporous, acid–base bifunctional, and superhydrophobic polymeric solid catalyst for the production of HMF from cellulose in a one-pot manner. The catalyst are well characterized by field emission scanning electron microscopy, fourier transform infrared spectroscopy, 13C solid-state nuclear magnetic resonance spectroscopy, X-ray photoelectron spectroscopy, pyridine fourier transform infrared spectroscopy and NH3/CO2 temperature-programmed desorption. Results of characterization demonstrated that the as-prepared catalyst possesses average void diameter at 12.5μm, interconnecting pore diameter at 2.8μm, contact angle at 150°, acid strength at 3.034mmolg−1 and base strength at 1.379mmolg−1, respectively. By simply varying the parameters of HIPEs templates (i.e., the volume fraction of the internal phase and surfactant concentration), the molar ratio between acid/base monomer and the grafted amount of 1-dodecanethiol, the pore structure, acid and base strengths, wettabilities of catalyst can be easily adjusted. Results of catalytic experiments involving cellulose-to-HMF conversion indicated that as-prepared catalyst can effectively improve the reaction rate, increase the HMF yield and prohibit the hydration of HMF to by-products. And remarkable HMF yield of 49.5% and selectivity of 55.9% can be obtained from 100mg cellulose under the optimal conditions. Furthermore, catalyst can be easily recovered and reused at least five times without significant loss of catalytic activity. This work represents a continuation of efforts for fabrication and application on multi-functional heterogeneous catalyst for excellent conversion of one-pot cellulose to HMF.