Xu Longya

Alkylation Performance of Thiophene and Its Derivatives during Olefinic Alkylation of Thiophenic Sulfur in Gasoline

Abstract The alkylation performance of thiophene and its derivatives (such as 2-methylthiophene, 3-methylthiophene, and 2,5-dimethylthiophene) with 1-hexene was investigated in a fixed-bed reactor. The results showed that thiophene and all its derivatives could be mono-alkylated with 1-hexene easily, and their conversion was close to 100% under experimental conditions. However, with the increase of the number of the branched chain on the thiophene ring, the di- and tri-alkylation capability of thiophene derivatives decreased a lot because of the thermodynamics and steric effects, and their primary products are restricted to the mono-alkylated products. The decrease in alkylation capability of thiophene derivatives enhanced the other two parallel competitive reactions, the aromatics alkylation and alkene alkylation (or called alkene oligomerization). The relative content of their further alkylated products was even more than that of the mono-alkylated products during the alkylation of dimethylthiophene.

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.

n-Hexane Isomerization by Pt/WO3-ZrO2 Using Hydrothermally Synthesized Hydrous Zirconia as Support

Abstract A series of hydrous zirconia samples were prepared by the hydrothermal method, and the Pt/WO3-ZrO2 catalyst was prepared by impregnation. The effects of hydrothermal temperature of Zr(OH)4 on the isomerization activity of the catalyst was investigated. The crystalline structure, acidity, and reduction properties of the catalyst were characterized by X-ray diffraction, NH3 temperature-programmed desorption, and H2 temperature-programmed reduction, respectively. The results indicated that the crystalline structure of hydrous zirconia and the catalyst varied with the hydrothermal temperature, and the increase of hydrothermal temperature reduced the fraction of tetragonal zirconia. Strong acid sites on the catalyst and the isomerization activity increased with the crystallization of Zr(OH)4. It was proposed that the higher isomerization activity may be related to the existence of large numbers of strong acid sites.

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.

Effect of Crystallization of Hydrous Zirconia on the Isomerization Activity of Pt/WO3-ZrO2

Abstract A series of crystalline hydrous zirconia supports were prepared by different methods. The preparation method affected the crystallization mode of supports and catalytic activity of Pt/WO 3 -ZrO 2 for n -hexane isomerization. The catalysts were characterized by X-ray photoelectron, Raman spectroscopy, and NH 3 temperature-programmed desorption. The crystallization mode of hydrous zirconia was affected by the ambience used in the synthesis. Crystalline hydrous zirconia prepared in the absence of oxygen led to a catalyst with high activity, and the case was the opposite when it was prepared in the presence of oxygen.