Isobutane Isomerization Over Nickel And Cooper Supported WO₃-ZrO₂ Super Acid Catalyst

N-butane is an important chemical industrial raw material,which can be used for producing maleic anhydride andγ-butyrolactone.With the increasing demand for maleic anhydride andγ-butyrolactone,the demand for n-butane is also increasing.The domestic demand for ethylene is increasing.Steam cracking is the main method of industrial production of ethylene.C₄ become one of important feedstocks for steam cracking of ethylene.As the main component of C₄,the yields of ethylene are 18%and 48%for isobutane and n-butane respectively.Presently,isobutane obtained from C₄ is used to prepare methyl tert-butyl ether（MTBE）gasoline additive.However,MTBE has been banned in many countries due to its harm to environment.Therefore,conversion of isobutane to n-butane has theoretical significance and practical application value.In the process of isobutane hydroisomerization of n-butane,Pt-Cl/Al₂O₃ reported in the literature has the characteristics of continuous chlorine supplement and catalyst deactivation.WO₃-Zr O₂ was prepared as the support and loaded with Ni and Cu.Through adjusting the preparation conditions such as WO₃ loading,metal loading,and type of metal-acid.Therefore,the ratio of metal to acid centre was controlled and then the activity of the catalyst was improved.Solid superacid WO₃-Zr O₂ was prepared by coprecipitation method and then Ni/WO₃-Zr O₂ with different Ni loading was prepared by equal volume impregnation method.XRD,N₂ adsorption-desorption,SEM,NH₃-TPD,H₂-TPR were used to characterize the composition,structure and morphology of x Ni/WO₃-Zr O₂ Catalyst.The experimental results show that the conversion of isobutane is 44.16%and the selectivity to n-butane is40.07%over 1Ni/WO₃-Zr O₂ catalyst under the reaction condition of 420℃,2.5 MPa,n（H₂）/n（C₄）=4.0 and LHSV=1.0 h^-1.The results show that the addition of Ni can effectively inhibit the cracking reaction on the catalyst.Moreover,the appropriate metal acid site ratio could improve the selectivity to n-butane.In order to further improve the activity of 1Ni/WO₃-Zr O₂,bimetallic catalyst Ni Cu/WO₃-Zr O₂ were prepared by co-impregnation,and XRD,XPS,N₂ adsorption-desorption,SEM,NH₃-TPD,H₂-TPR and other methods were used for the characterization of catalysts.The characterization results showed the active component was supported on the support in the form of Ni-Cu alloy.According to the activity evaluation results,cracking of isobutane could be inhibited on the catalyst.The addition of a small amount of Cu does not reduce the conversion of the catalyst.The experimental results show that the conversion of isobutane is 60.12%and the selectivity to n-butane is 65.33%over 1Ni1Cu/WO₃-Zr O₂catalyst under the condition of 450℃,2.5 MPa,n（H₂）/n（C₄）=4.0 and LHSV=1.0h^-1.These results show that the addition of Cu could improve the selectivity to n-butane.