Investigation of catalytic activity of CrSBA-1 materials obtained by direct method in the dehydrogenation of propane with CO2

A series of the Cr-containing SBA-1 (xCrSBA1) cubic mesoporous catalysts with various Cr/Si molar ratios have been prepared by direct method using cetyltriethylammonium bromide, ammonium dichromate, tetraethyl orthosilicate and hydrochloric acid. The obtained materials have been characterized by different physicochemical techniques including ICP, XRD, UV-vis DRS, H-2-TPR and N-2-adsorption. XRD and N-2-adsorption results have revealed that xCrSBA1 materials possess well organized three-dimensional pore structure. However, incorporation of Cr into the SBA-1 framework leads to small perturbation of the structural order. ICP results have shown that the amount of Cr incorporation in SBA-1 can be controlled by adjustment of the molar ratio of (NH4)(2)Cr2O7 to Si(C2H5O)(4) in the gel. Finally, the catalytic activity of pure SBA-1 and Cr-containing SBA-1 materials were investigated in the dehydrogenation of propane with CO2. In the case of the most active, 0.04CrSBA1 catalyst, the effect of various reaction parameters such as, reaction temperature, reaction time and feed gas composition on the conversion of propane, yield and selectivity to propene as well as on molar ratio of CO/H-2 has been evaluated. Moreover, stability of the catalyst during the dehydrogenation/regeneration conditions was studied as well. It has been found that during the fourth consecutive cycle the catalyst undergoes two types of deactivation processes - reversible and irreversible. The former is caused mainly by the coke deposition, which can easily overcome by air treatment of the catalyst at 550 degrees C. The latter one, insignificant, is due to partial collapse of mesoporous structure of the catalysts. (c) 2009 Elsevier B.V. All rights reserved.