Utilization of lignite derivatives to construct Zr-based catalysts for the conversion of biomass-derived ethyl levulinate

With the fast depletion of fossil resources, exploring the value-added utilization approaches of low rank coals and promoting the conversion of sustainable biomass resources into useful chemicals are critical topics facing human society. In this work, we attempted low rank lignite as raw materials to construct novel Zr-based catalysts for biomass conversion using the abundant oxygen-containing groups and specific network structures of lignite. Two components of lignite, i.e. humic acids (HA) and the solid residues (SR) after HA extraction, were used to prepare the catalysts. The prepared catalysts were applied into the conversion of biomass-derived ethyl levulinate (EL) to gamma-valerolactone (GVL), an important reaction for the conversion of biomass resources. Both the preparation conditions of the catalysts and the parameters during catalytic reaction process were systematically investigated. The structures of the catalysts were characterized by SEM, TEM, FTIR, powder XRD, and TG analysis. The results demonstrated that the route using lignite as raw materials to construct Zr-based catalysts was feasible, and the designed catalysts were highly efficient for the conversion of EL into GVL. The conversion of EL, GVL yield and selectivity could reach up to > 90% under suitable conditions. The catalysts could be used at least 11 recycles without notable changes in both performances and structures, indicating an excellent stability. This work may provide potential ways for both value-added utilization of low rank coals and construction of efficient catalysts for biomass conversion.