The dehydrogenation of ethylbenzene with CO2 over V2O5/CexZr1−xO2 prepared with different methods

Abstract The high-surface-area Ce x Zr 1− x O 2 composite oxides with various compositions were prepared with modified hydrothermal and sol–gel methods, respectively. Different amounts of vanadia were loaded via an incipient wetness technique for the preparation of the V 2 O 5 /Ce x Zr 1− x O 2 . The prepared samples were subjected to the dehydrogenation of ethylbenzene (EB) in the presence of CO 2 in a fixed-bed reactor under the conditions of T  = 823 K, P  = 1 atm, and CO 2 /BE molar ratio = 20. The hydrothermal Ce x Zr 1− x O 2 loaded with 6 wt.% V 2 O 5 showed obviously higher EB conversion than the 6 wt.% V 2 O 5 /Ce x Zr 1− x O 2 (sol–gel) although similar styrene selectivity was obtained. Moreover, the V 2 O 5 loadings and the Ce/Zr ratios had clear influence on both the activity and the stability of the catalyst. Irrespective of the preparation methods and Ce/Zr ratios, XRD results indicate that nanocrystalline Ce x Zr 1− x O 2 solid solution was exclusively formed. Independent of the Ce/Zr ratios, the Ce x Zr 1− x O 2 prepared with hydrothermal method was composed of pure cubic phase while mixed phases were observed for the sol–gel samples as revealed from Raman results. With increasing vanadia loadings from 3 to 15 wt.%, different forms of vanadium species, such as vanadates and crystalline V 2 O 5 , were observed from Raman spectra. Irrespective of the V 2 O 5 loadings, a single-step reduction of the supported V 2 O 5 was revealed from the TPR patterns. Based on these and the TGA/DSC analysis of the used catalysts, the experimental results were extensively discussed and tentatively explained.