Facile use of lignite as robust organic ligands to construct Zr-based catalysts for the conversion of biomass derived carbonyl platforms into alcohols

Abstract

Use of lignite under mild conditions without destroying the natural functional groups and structures is a potential approach for the value-added utilization of lignite. Considering the abundant acidic functional groups in lignite, in this work, a novel and facile route using lignite as robust organic ligands to construct Zr-based catalysts was proposed, and the designed catalysts were applied in the conversion of biomass-derived carbonyl molecules into valuable chemicals. The universality of the proposed route for different rank coals and substrates with various structures were analyzed. Both the preparation conditions of the catalysts and the reaction parameters were systematically investigated. The obtained catalysts were characterized by SEM-EDS, XRD, FTIR, Raman, and TG, etc. The results demonstrated that the designed catalysts were highly efficient for the selective conversion of furfural into furfuryl alcohol. Under the optimized conditions, the conversion, yield, and selectivity were up to 93.4%, 81.0%, and 86.7%, respectively. Both the reaction conditions and the performances of the catalyst were competitive compared with analogous catalysts. It was proved that the catalyst was heterogeneous and the reusability could be improved through demineralization of lignite via acid washing before use, and the catalyst prepared by demineralized lignite had no obvious changes in both performances and structures after 5 reuses. The proposed route was also identified to be applicable for other low rank coals besides lignite, such as long flame coal and coking coal. The catalyst prepared using lignite was robustly effective for the conversion of various carbonyl compounds with different structures, indicating the broad universality for different substrates. Detailed characterization showed that the performances of the catalyst were jointly influenced by both Zr contents and surface areas of the catalyst. This novel route of constructing Zr-based catalysts using low rank coal as raw materials is highly potential for application in the utilization of low rank coals and biomass resources, with the advantages of high efficiency of the catalysts, low cost of raw materials, and simple preparing process.