Different Supports-Supported Cr-Based Catalysts for Oxidative Dehydrogenation of Isobutane with CO2

Abstract

The effect of supports (MSU-1,), gamma-Al2O3, AC (activated carbon), and MgO) on the catalytic activity of Cr-based catalysts was investigated for the dehydrogenation of isobutane with CO2. The catalytic activity was in the order of CrO,IMSU-1 > CrOx/Al2O3 > CrOx/AC > CrOx/MgO. The catalysts were characterized by N-2 adsorption-desorption, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and temperature-programmed desorption (TPD). The XRD results indicate that the active species of Cr are dispersed well on the supports. N-2 adsorption-desorption shows that the support MSU-1 has the largest surface area (804.2 m(2)/g), which results in excellent dispersion of Cr and highest activity. The XPS results reveal that Cr6+ is one of the active centers. The results of NH3-TPD indicate that catalyst activity is proportional to the amount of weak acid adsorption sites. As a result, the best support is the MSU-1 zeolite owing to its high specific area and a large amount of weak acid sites. The 59.2% conversion of isobutane and the 39.5% yield of isobutene are achieved on the CrOx/MSU-1 catalyst.