Font Size: a A A

Studies On The Improvement Of Selectivity Of VO_x/SBA-15 Catalysts For The Oxidative Dehydrogenation Of Propane To Propene

Posted on:2009-04-01Degree:MasterType:Thesis
Country:ChinaCandidate:J P GuoFull Text:PDF
GTID:2121360272490206Subject:Physical chemistry
Abstract/Summary:PDF Full Text Request
The issue of improving the selectivity to the desired product is the most important in the case of selective oxidation of light alkanes.This dissertation contributes to the studies on modifying effect of alkali metals and preparations by different routes on the physico-chemical characteristics and the performance of VOx/SBA-15 catalysts for the oxidative dehydrogenation of propane(ODHP).The main results are summarized as follows:1) The effect of alkali metal additives on the performance of single-site (pseudotetrahedral monovanadate VO4 ) VOx/SBA-15 catalysts was investigated.The addition of alkali metals significantly improved the selectivity of propene which was enhanced by~10%at the same propane conversions.Raman,H2-TPR,Py-IR,NH3-TPD results indicated that the addition of a small amount(A/V≤0.05) of alkali metals did not change the structure and reducibility of active centers but resulted in a decrease of Bronsted acid sites which favors propene desorption and prevents the overoxidation of propene to carbon oxides.2) VOx-SBA-15 catalyst was synthesized by in situ coating route in a one-pot process.BET,XRD results indicated that the ordered mesostructure of the siliceous SBA-15 was preserved.Raman and H2-TPR results showed that the good performance of catalysts prepared by in situ coating route for ODHP was related to the better reducibility and dispersion of the VO4 species on the surface compared with samples prepared by the wet impregnation method.
Keywords/Search Tags:Propane, Oxidative dehydrogenation, Vanadia catalylsts, SBA-15, Alkali metals
PDF Full Text Request
Related items