The Structure And Properties Of Cu-based And Pt-based Catalysts For Glycerol Hydrogenation To Propanediol

By converting biodiesel-byproduct glycerol to other high value-added chemical products,the cost of biodiesel technology can be reduced.Research on catalysts for catalytic hydrogenation of glycerol to propanediol has both theoretical and practical significance.In this dissertation,the relation between the composition,surface properties and the catalytic performance of glycerol hydrogenation of Cu-ZnO,Cu-Ni-ZnO,Pt/WO3/ZrO2 catalysts has been studied by using micro-reactor tests combined with BET surface area measurements,X-ray diffraction(XRD),Laser Raman spectra(LRS),X-ray photoelectron spectroscopy(XPS),H2 temperature-programmed reduction(H2-TPR),and NH3 temperature-programmed desorption(NH3-TPD).Important reference information for a suitable catalyst for catalytic hydrogenation of glycerol to propanediol is also provided.The experimental results have shown that:1.In the Cu-ZnO catalyst for glycerol hydrogenation,Cu0 provides the dehydration function as well as the hydrogenation function,while ZnO promoted the reduction of Cu and the dispersion of Cu0.Also,there is a close link between the Cu amount in Cu-ZnO catalyst and the reactivity for glycerol hydrogenation.With an increase in Cu content,the selectivity of 1,2-propanediol increased,and the glycerol conversion initially increased and then decreased if more Cu was added.The optimum conversion was recorded with the catalyst of Cu/(Cu+Zn)=0.65.Glycerol hydrogenation results showed that forming Cu-ZnO catalyst still maintained a good stability after 200h reaction.Using the saponification byproduct glycerol as raw material,forming Cu-ZnO catalyst showed a good application prospects with 94 mo%glycerol conversion and 80 mol%1,2-propanediol selectivity.2.Adding an appropriate amount of Ni can further optimize the catalytic performance of Cu-ZnO catalyst in glycerol hydrogenation to 1,2-propanediol.With an increase in Ni content in Cu-Ni-ZnO catalyst,glycerol conversion changed little,but the selectivity of 1,2-propanediol increased significantly.A Suitable Ni dosage is in the range:Ni/Cu molar ratio<0.5.Excess Ni led to the decrease of glycerol conversion.3.The WO3 component in Pt/WO3/m-ZrO2 catalyst was proved to be able to significantly promote the glycerol conversion to 1,3-propanediol.This may be related to the HxWO3 proton acid caused by the hydrogen spillover between Pt and WO3.With the WO3 content increased,glycerol conversion and 1,3-propanediol selectivity increased greatly.When WO3 content exceeded its dispersion capacity(3.2W/nm2 m-ZrO2),1,3-propanediol selectivity remained essentially the same,but Pt dispersion decreased,resulting in glycerol conversion decrease.The suitable WO3 content in Pt/WO3/m-ZrO2 catalyst should be around the WO3 dispersion capacity on the m-ZrO2 carrier.