Wang Qingxia

The suppression of coke deposition by the modification of Mn on Fe/silicalite-2 catalyst in dehydrogenation of C2H6 with CO2

Abstract For the dehydrogenation of C 2 H 6 with CO 2 to C 2 H 4 , a silicalite-2 zeolite supported Fe–Mn catalyst has been developed, with an achievement of 93% of C 2 H 4 selectivity and 66% of C 2 H 6 conversion. The promotion of Mn to the Fe/Si-2 catalyst lies not only in increasing C 2 H 4 selectivity but also in improving the catalytic stability greatly. A thermo-balance was employed to investigate the behavior of coke deposition on Fe/silicalite-2 and Fe–Mn/silicalite-2 catalysts during C 2 H 6 dehydrogenation. By studying the effects of reaction temperature and partial pressures of C 2 H 6 and CO 2 on coke deposition, the kinetic parameters of the coking reaction were satisfied and the corresponding coking reaction kinetics equations were thus established. The rate of coke deposition on Fe–Mn/silicalite-2 is much less than that on Fe/silicalite-2, due to the modification of Mn to the Fe/silicalite-2 catalyst. The promotion of Mn to the improvement of the catalytic stability of the Fe/silicalite-2 catalyst results from the great prohibition of coke formation on Fe–Mn/silicalite-2 catalyst surfaces.

A New Route for C2H4 Production by Reacting C2H6 with CO2 over a Catalyst of Chromium Oxide Supported on Silicalite-2 Type Zeolite

A Cr/Si-2 catalyst was developed to possess good reactivity for the formation of ethylene from ethane oxidative dehydrogenation with CO 2 . The addition of Mn and La oxide could improve the reactivity of the catalyst. It was also found that increasing the CO 2 /C 2 H 6 ratio of the feed gas could increase the ethane conversion and ethylene selectivity of the Cr/Si-2 catalyst. Besides, addition of steam to the feed gas could diminish coke formation during the reaction process. The main reactions for the dehydrogenation of ethane with CO 2 to ethylene have been deduced to consist of the cracking of ethane to ethylene and CO 2 hydrogenation to CO.

CO2 Hydrogenation for the Production of Light Alkenes over K-Fe-Mn/silicalite-2 catalyst

MnO and K 2 O are two kinds of promoters to Fe/Silicalite-2 (denoted as Fe/Si-2) catalyst for light olefin formation from CO 2 hydrogenation. It has been revealed that CO 2 adsorption capacity was enhanced by the addition of MnO, and that K 2 O could further increase both the adsorption capacity and bonding strength of the Fe-Mn/Si-2 catalyst to CO 2 and CO species. Based on a two step reaction mechanism in which a reversible water gas shift reaction and a Fischer-Tropsch reaction are involved, the promotional effects of these two kinds of promoters for the formation of C 2 H 4 and C 3 H 6 can be explained.

Study of the surface acidity before and after heat or steam treatment for P or Mg modified ZSM-5 zeolites

Abstract The method of adsorption of vapor of basic substance (C 2 H 5 NH 2 ) was employed to determine acidity of ZSM-5 catalyst. Effects of heat or steam treatment on acidity of modified ZSM-5 catalysts have been studied by TG-DTG and de-ethylamination activation energy was obtained by Broid method from TG data. Also,effects of heat and steam treatment on selectivity of modified ZSM-5 catalysts were examined.