High-Efficiency Production of Biomass-Derived 5-Alkoxymethylfurfurals over a Lewis-Bronsted Bifunctional Carbonaceous Acid Catalyst

Biomass-derived 5-alkoxymethylfurfurals (AMFs) are an important kind of high-quality liquid biofuel or diesel additive, which are commonly produced by the etherification of 5-hydroxymethylfurfural (HMF) with alcohols. To produce various AMFs in a convenient and practical manner, the design of high-performance catalysts with preeminent catalytic universalities is a particularly interesting and meaningful task. Herein, we developed a useful carbonization-coordination-sulfonation strategy, which was employed to construct a Lewis-Br & oslash;nsted bifunctional carbonaceous acid catalyst (Zr/GHTC-SO3H). The characterization results demonstrated that Zr/GHTC-SO3H contained strong Lewis acidic sites (Zr4+) and Br & oslash;nsted acidic sites (-SO3H), which could promote the etherification of HMF and then facilitate the formation of AMFs. Simultaneously, Lewis basic sites (O2-) in Zr/GHTC-SO3H were dramatically destroyed and weakened, which could restrict the transfer hydrogenation of HMF and then improve the selectivity of AMFs. Due to the synergistic effects of different active sites, Zr/GHTC-SO3H showed excellent catalytic performance and catalytic universality. When HMF was etherified in methanol, ethanol, n-propanol, isopropanol, n-butanol, and sec-butanol, the corresponding product yield could be up to 91.6, 94.8, 93.3, 94.4, 92.9, and 92.1% under the appropriate reaction conditions, respectively. Moreover, Zr/GHTC-SO3H was also a stable catalyst and displayed satisfactory reusability. In summary, this work presented a special research idea to prepare high-efficiency catalysts for the etherification of HMF to AMFs, which could also provide significant references for the production of other biomass-derived furanic ethers.