Research On Ni₂P Catalyst To Catalytic Dehydrogenation Of Propane To Propylene And Modification Of Carrier

Propylene is an important chemical raw material,and the world demand for propylene is growing steadily in recently years.As a new propylene production process,propane dehydrogenation to propylene has become the focus of global attention.It is of great significance to improve the high added value of propane.At present,Cr based catalysts has been widely used for propane dehydrogenation because of its cheap and anti-poisoning.In addition,transition metal phosphide Ni2P named "platinum-like metal" has good hydrogenation dehydrogenation ability.If Ni2P can be used for propane dehydrogenation catalyst,not only can solve the problem of expensive of Pt,no pollution to the environment.The contents of this paper mainly include two parts:(1)In this work,?-Al2O3 was used as carrier,NiCl2·6H2O and NaH2PO2·H2O as precursors.The transition metal phosphide catalysts with different Ni2P loading were prepared by hydrothermal method.The catalysts were characterized by N2 adsorption at-196?,temperature-programmed desorption of ammonia(NH3-TPD),X-ray diffraction(XRD),Scanning Electron Microscope(SEM)and thermogravimetric(TG).Result shows that the optimum reaction conditions of Ni2P/Al2O3 catalysts were temperature 620? and WHSV 3h-1.The catalytic activity of 20%Ni2P/Al2O3 catalyst was the best under different Ni2P loadings and the same reaction conditions.The conversion and selectivity were about 25%and 75%,respectively.(2)In this paper,?-Al2O3 was used as carrier,CrO3 as precursor and alkaline earth metal and rare earth metal as additive.The carrier was pretreated by different acid and alkali materials and oxides.The catalysts were characterized by N2 adsorption at-196?,temperature-programmed desorption of ammonia(NH3-TPD),X-ray diffraction(XRD),Scanning Electron Microscope(SEM)and Fourier Transform Infrared Spectrometer(FTIR).The experimental shows that the acidity of catalysts surface has a great influence on the catalytic performance,the more acidic,propane conversion rate is high,the catalyst deactivated easily.The catalyst modified by 30? distilled water has good catalytic activity and stability.The catalyst modified by ZrO2 has high catalytic activity,and the conversion and selectivity are about 45%and 90%.