Shape-selective alkylation of benzene in aromatic mixtures over zeolites for benzene reduction in gasoline

Shyamal Kumar Saha, Uday T. Turaga, Chunshan Song

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

It would be desirable to reduce benzene in gasoline by alkylation. This work examined three zeolite catalysts with different topologies including ZSM-5(50), BEA(38) and Y(30) where the figure indicates the Si/Al2 ratio.. Isopropylation of aromatics with propylene was studied using model feeds (5 wt.% benzene; 5 wt.% toluene; and 5 wt.% m-xylene in octane) with corresponding molar ratios of (benzene:toluene:m-xylene=1.0:0.84:0.73) in a down-flow fixed bed reactor at 250°C with WHSV 3.75 h-1. The structure type and acid nature of porous materials strongly affected their catalytic activity and stability for benzene alkylation. The BEA and ZSM-5 catalysts selectively promoted benzene conversion over toluene and m-xylene. On the other hand, Y zeolite gave higher m-xylene conversion than benzene conversion. The ZSM-5 catalyst showed higher benzene selectivity than the BEA catalyst. However, catalytic activity of BEA zeolite for benzene conversion was much higher (30%) than that of ZSM-5 (10%) even though the former shows lower acidity. The ZSM-5 catalyst was much less stable compared to BEA zeolite. It was observed that BEA zeolite was very stable up to 6 h time on stream among the three catalysts examined. The reactivity in reactions using ZSM-5 and BEA zeolites ranked in the order of Benzene> Toluene> m-Xylene. However, Y-zeolite showed the opposite trend which may be due to different features of the pore channel. In the case of ZSM-5 and BEA zeolites, the channel opening is only slightly larger than the size of a benzene molecule and does not permit the entrance of m-xylene. As a result, benzene is more selective than toluene and m-xylene over said catalysts. BEA zeolite showed the highest conversion of benzene and more stable catalytic performance under the conditions employed.

Original languageEnglish (US)
Title of host publicationAmerican Chemical Society - 238th National Meeting and Exposition, ACS 2009, Abstracts of Scientific Papers
StatePublished - Dec 1 2009
Event238th National Meeting and Exposition of the American Chemical Society, ACS 2009 - Washington, DC, United States
Duration: Aug 16 2009Aug 20 2009

Publication series

NameACS National Meeting Book of Abstracts
ISSN (Print)0065-7727

Other

Other238th National Meeting and Exposition of the American Chemical Society, ACS 2009
CountryUnited States
CityWashington, DC
Period8/16/098/20/09

All Science Journal Classification (ASJC) codes

  • Chemistry(all)
  • Chemical Engineering(all)

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    Saha, S. K., Turaga, U. T., & Song, C. (2009). Shape-selective alkylation of benzene in aromatic mixtures over zeolites for benzene reduction in gasoline. In American Chemical Society - 238th National Meeting and Exposition, ACS 2009, Abstracts of Scientific Papers (ACS National Meeting Book of Abstracts).