Hydrogenation of biomass lactones to diols over CuLax/γ-Al2O3 catalyst：The promoting role of LaOx

The activation and ring opening reaction of lactone bond is of great significance in biomass utilization. Cu-based catalysts are widely used in the biomass hydrogenation processes, in which the effect of oxide promoters on Cu catalysts is one of the most attractive research topics. Herein, the transformation of lactones to diols over Cu/Al 2 O 3 and CuLa x /Al 2 O 3 catalysts was studied and the promoting role of LaO x has been discussed. The CuLa 0.25 /Al 2 O 3 catalyst showed outstanding catalytic performance with high 1,4-butanediol yield of > 90 %, and it also showed high efficiency for the hydrogenation of series of five- and six-membered lactones (γ-butyrolactone, γ-valerolactone, δ -hexalactone, etc) to diols. Based on the comprehensive analysis of the XRD, TEM, TPR, XPS, low temperature CO-DRIFT results, the crucial contribution of LaO x species in promoting the selectivity and stability of catalysts were investigated in detail. The presence of LaO x species not only results in the formation of Cu + -LaO x interfacial active sites, which facilitate the adsorption and activation of lactones, but also promotes the stability of catalyst.