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

The high-surface-area CexZr1−xO2 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 V2O5/CexZr1−xO2. The prepared samples were subjected to the dehydrogenation of ethylbenzene (EB) in the presence of CO2 in a fixed-bed reactor under the conditions of T = 823 K, P = 1 atm, and CO2/BE molar ratio = 20. The hydrothermal CexZr1−xO2 loaded with 6 wt.% V2O5 showed obviously higher EB conversion than the 6 wt.% V2O5/CexZr1−xO2(sol–gel) although similar styrene selectivity was obtained. Moreover, the V2O5 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 CexZr1−xO2 solid solution was exclusively formed. Independent of the Ce/Zr ratios, the CexZr1−xO2 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 V2O5, were observed from Raman spectra. Irrespective of the V2O5 loadings, a single-step reduction of the supported V2O5 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.

The high-surface-area CexZr1−xO2 solid solutions (max. ∼130 m2/g) were prepared with different methods, and the V2O5/CexZr1−xO2 showed high activity and selectivity for the dehydrogenation of ethylbenzene in the presence of CO2.Figure optionsDownload high-quality image (60 K)Download as PowerPoint slide