Highly Dispersed Au And Support Synergistically Catalyzing The Oxidation Of Glycerol To Dihydroxyacetone

Glycerin is an important biological platform molecule.The marketing of glycerol is saturated and the capacity is excessive.Therefore,the conversion of glycerol to the high value-added chemicals is of great significance for the efficient use of glycerol.Selective oxidation of glycerol could produce a variety of high value-added chemicals.Among them,hydroxyacetone(DHA)is an important widely-used platform chemical in the fields of medicine,nursing,food,industry and so on.Therefore,the direct selective oxidation of DHA from glycerol is of great strategic importance.However,the oxidation reaction network of glycerol is complicated and the selectivity of the specific product is relative low.To achieve high selectivity of DHA requires the selective oxidization the secondary hydroxyl group,the suppression of the deep oxidation,and the suppression of C-C bond cleavage.Therefore,the efficient conversion glycerol to DHA is still a great challenge.In this work,based on the layered double hydroxides(LDHs)and the mixed metal oxide(LDO)as supports,highly dispersed Au catalysts have been prepared.The work is focused on the synergistic effect of the basity of the support or the metal-support interfacial interaction with the Au metal active site,which could efficiently enhance the activity and selectivity of the selective oxidation of glycerol to DHA.The main research work is displayed as follows:1.Taking the advantages structural features that the metal cations of the hydrotalcite plates LDH layer are highly dispersed at an atomic level and the composition is adjustable,the ZnGa-LDHs,MgAl-LDHs,ZnAl-LDHs,ZnFe-LDHs and CoAl-LDHs have been prepared.Through the deposition-precipatation with urea and subsequent liquid phase reduction,highly dispersed Au supported LDH catalysts have been prepared.The Au metal active sites in the supported Au catalysts were uniformly dispersed,showing good activity and high DHA selectivity in the selective oxidation of glycerol to DHA.The structure regulations of the Au active site and basity properties of LDHs towards the chemical composition of LDHs have been investigated in detail.The synergistic catalysis of Au active site and LDHs has been studied through exploring the relationship between the structure regulation and the catalytic performance.2.Based on the topological transformation characteristics of LDHs,Au/ZnGa-LDO catalyst has been prepared by annealing of the Au3+/ZnGa-LDHs precursor.Through the modulation of chemical composition in the LDH precursors layers and the topological transformation conditions,the interface structure between Au active sites and the LDO support has been regulated.The synergistic catalysis of Au active site and LDO has been studied through exploring the relationship between the interfacial structure and the catalytic performance.It is found that the introduction of Ga leads to strong interfacial interaction between Au and the LDO support.For Au/Zn2Ga-LDO catalyst,a glycerol conversion of 98%and a DHA selectivity of 54.8%has been achieved.