| A series of vanadium catalysts supported on ZSM-5zeolite in the dehydrogenation of propane to propylene in the presence of CO2were prepared via an incipient wetness impregnation method (IM). The powder H-ZSM-5was impregnated with NH4VO3(Sigma-Aldrich,≥90%) aqueous solutions of various concentrations to obtain different V loadings (0,2,4,6,8and10wt%V, respectively). The catalysts were subsequently characterized by BET surface area, X-ray diffraction (XRD), FT-IR, NH3-TPD, H2-TPR and X-ray photoelectron spectra (XPS) as well as measurement of the catalytic performance. Comparing propylene selectivity as function of propane conversion the most selective catalysts were the6VOx/ZSM-5samples, which contained mostly vanadia monomers according to Raman spectroscopy. The best propylene yield of26%was obtained with the6VOx/ZSM-5samples.vanadium-containing silicate zeolite (V-ZSM-5) was prepared by post-hydrothermal synthesis after alkali treatment condition. An aqueous solution of vanadyl sulfate (VOSO4·3H2O) was added slowly into an aqueous solution containing TPABr (Tetrapropylammonium bromide). In as-synthesized form, the structure and nature of vanadium species as well as their interactions with ZSM-5are compared using SEM, Raman, UV-vis, FT-IR and spectroscopic techniques. The V5’ ions are incorporated into the lattice of ZSM-5during synthesis, which leaded to rough surface, disorder micropore structure and the descreasing of degree of crystallinity. Moreover, comparing propylene selectivity as function of propane conversion the most selective catalysts were the0.7V-ZSM-5samples, the best propane conversion of which obtained was37.8%.In the final, the study preliminarily explored the performance of the moulding catalyst. Alumina hollow fiber micro filtration membrane as supporter was impregnated with NH4VO3(Sigma-Aldrich,≥90%) aqueous solutions of various concentrations more than once. The results indicated that the performance of the samples did not show well because of low V loadings. |
PDF Full Text Request