Synthesis Of Metal Oxide Nanoparticles And Their Application In The Oxidative Dehydrogenation Of Propane To Propene

Since the oxidative dehydrogenation of propane is exothermic and can be achieved at low temperature,it has aroused wide attention of researchers.Metal oxide nanomaterials such as vanadium oxide,molybdenum oxide,chromium oxide and nickel oxide are usually used as catalysts for this reaction,and their catalytic properties are always related to various factors such as size,morphology,exposed crystal surface,crystal structure,type of support,and concentration of active site.From the point of redox properties of catalysts,these factors lead to the different types and concentrations of oxygen species on the surface of nanomaterial,and then affect the activation of hydrocarbon bonds and the oxidation degree of the reactants during the reaction.Through the introduction of other elements to regulate the surface electron structure of nanoparticles,we can effectively alleviate the deep oxidation on the surface of catalysts and improve the selectivity of olefin.In this paper,Cerium oxide and nickel oxide nanomaterials were used as catalysts for the PODH reaction.By introducing other elements to the catalyst,the electronic structure of metal oxide nanomaterials was regulated and the selectivity of propylene selectivity was improved.(1)Ceria oxide nanomaterials with different morphologies were prepared by hydrothermal method,and then Cl were introduced into the surface of CeO2 by hydrochloric acid treatment.Both catalysts before and after treatment were applied to the oxidative dehydrogenation of propane reaction.By comparing the catalyst before and after the acid treatment,it was found that the selectivity of CeO2 nanorods increased from 2.5%to 42.5%at the same 10%propane conversion.The presence of chloride ions on the surface of CeO2 after acid treatment was confirmed by XRD,TEM,HRTEM,XPS,H2-TPR and other characterizations.It was found that chloride was more inclined to keep on the(110)plane of CeO2 nanorod and substitute partial oxygen on the surface of the catalyst.Thus,the deep oxidation was suppressed through reducing the excess oxygen species.(2)NiO nanoparticles with a size of about 20 nm was prepared by hydrothermal method,and the electronic structure of the nickel oxide material was regulated by the deposition of a series of tungsten on the surface.Compared pure NiO nanoparticle and 1.5%W-NiO,the selectivity of propylene(under about 10%propane conversion)was 29.2%to 60.9%,respectively.The selectivity of C3H6 was greatly enhanced through the deposition of tungsten.XRD,TEM,XPS,H2-TPR and Raman were used to confirm that tungsten had doped into the lattice of nickel oxide and affected the redox property of NiO.Therefore,the selectivity of C3H6 was increased by suppressing the deep oxidation.