Preparation of γ-Al2O3 via Hydrothermal Synthesis Using ρ-Al2O3 as Raw Material for Propane Dehydrogenation

摘要

γ-Al2O3 was prepared by hydrothermal synthesis usingρ-Al2O3 and urea as raw materials.In this work,the eff ects of the molar ratio of CO(NH2)2/Al and reaction temperature were investigated,and a Pt–Sn–K/γ-Al2O3 catalyst was prepared.The ammonium aluminum carbonate hydroxide(AACH),γ-Al2O3,and Pt–Sn–K/γ-Al2O3 were characterized by X-ray diff raction,scanning electron microscopy,transmission electron microscopy,N2 adsorption–desorption,thermogravimetry–differential thermal analysis,and NH3 temperature-programmed desorption techniques.The reactivity of Pt–Sn–K/γ-Al2O3 for propane dehydrogenation was tested in a micro-fixed-bed reactor.The results show thatγ-Al2O3 with a specific surface area of 358.1 m 2/g and pore volume of 0.96 cm 3/g was obtained when the molar ratio of CO(NH2)2/Al was 3:1 and the reaction temperature was 140℃.The alumina obtained by calcination of AACH has a higher specific surface area and larger pore volume than the industrial pseudo-boehmite does.The catalyst prepared from AACH as precursor showed high selectivity and conversion,which can reach 96.1%and 37.6%,respectively,for propane dehydrogenation.