Conversion of 5-hydroxymethylfurfural and carbohydrates to 5-ethoxymethylfurfural over chitin-derived solid acid catalysts

The use of environment friendly biomass-based catalysts in bio refinery is highly desirable. In this paper, the preparation of sulfonated carbon materials from biopolymers (typically chitin and cellulose) via facile one-step carbonization and sulfonation using p-toluenesulfonic acid as sulfonating agent was demonstrated. Unlike nitrogen-free cellulose, the basic nitrogen-containing sites generated from chitin decreased the acidity strength of the catalysts, which was confirmed by the results of 31 P Nuclear Magnetic Resonance ( 31 P NMR). The suppressed acidity strength boosted the selectivity of 5-ethoxymethylfurfural (EMF) from 5-hydroxymethylfurfural (HMF) by inhibiting the formation of by-products, such as ethyl levulinate (EL) and humins. An 84.3 % yield of EMF from HMF was obtained over the as-prepared chitin-derived solid acid. The catalyst could be reused at least three times without obvious decrease of catalytic activity. Moreover, 74.6 %, 31.9 % and 60.7 % yields of EMF were obtained from fructose, sucrose and inulin in ethanol-containing solvents, respectively. This work offers an example for the synthesis of biofuels using biomass-derived catalysts.