Chlorocuprate Ionic Liquid Functionalized Biochar Sulfonic Acid as an Efficiently Biomimetic Catalyst for Direct Hydrolysis of Bamboo under Microwave Irradiation

Abstract

A chlorocuprate ionic liquid functionalized biochar sulfonic acid (BCSA–IL-Cu) catalyst was proposed and conveniently prepared via grafting 1-trimethoxysilyl propyl-3-methyl imidazolium chloride (IL)-CuCl 2 (IL-Cu) onto biochar sulfonic acid (BCSA). The proposed catalyst showed much higher turnover numbers (TONs, 3.54 for cellulose and 2.42 for bamboo) for the direct hydrolysis of cellulose and especially bamboo in water under microwave irradiation, compared to the corresponding IL-functionalized BCSA (BCSA–IL, TONs, 3.22 for cellulose and 0.46 for bamboo) and BCSA (TONs, 1.51 for cellulose and 0.15 for bamboo). Reducing sugars were the main hydrolysis products, with a concomitant formation of a small amount of 5-hydroxymethyl furfural. This is likely because the BCSA–IL-Cu bearing −IL-Cu and −SO 3 H groups shows not only a biomimetic delignification (BDL) function, but also a functionality mimicking the cellulose binding domain (CBD) and catalysis domain (CD) of cellulose, as supported by the catalyst’s characterization and reaction results.