Reaction Mechanism for m- Xylene Oxidation in the Claus Process by Sulfur Dioxide
Type
ArticleKAUST Department
Clean Combustion Research CenterCombustion and Laser Diagnostics Laboratory
Mechanical Engineering Program
Physical Science and Engineering (PSE) Division
Date
2015-09-10Online Publication Date
2015-09-10Print Publication Date
2015-09-24Permanent link to this record
http://hdl.handle.net/10754/594140
Metadata
Show full item recordAbstract
In the Claus process, the presence of aromatic contaminants such benzene, toluene, and xylenes (BTX), in the H2S feed stream has a detrimental effect on catalytic reactors, where BTX form soot particles and clog and deactivate the catalysts. Among BTX, xylenes are proven to be most damaging contaminant for catalysts. BTX oxidation in the Claus furnace, before they enter catalyst beds, provides a solution to this problem. A reaction kinetics study on m-xylene oxidation by SO2, an oxidant present in Claus furnace, is presented. The density functional theory is used to study the formation of m-xylene radicals (3-methylbenzyl, 2,6-dimethylphenyl, 2,4-dimethylphenyl, and 3,5-dimethylphenyl) through H-abstraction and their oxidation by SO2. The mechanism begins with SO2 addition on the radicals through an O-atom rather than the S-atom with the release of 180.0-183.1 kJ/mol of reaction energies. This exothermic reaction involves energy barriers in the range 3.9-5.2 kJ/mol for several m-xylene radicals. Thereafter, O-S bond scission takes place to release SO, and the O-atom remaining on aromatics leads to CO formation. Among four m-xylene radicals, the resonantly stabilized 3-methylbenzyl exhibited the lowest SO2 addition and SO elimination rates. The reaction rate constants are provided to facilitate Claus process simulations to find conditions suitable for BTX oxidation. © 2015 American Chemical Society.Citation
Sinha S, Raj A, Al Shoaibi AS, Chung SH (2015) Reaction Mechanism for m- Xylene Oxidation in the Claus Process by Sulfur Dioxide . The Journal of Physical Chemistry A 119: 9889–9900. Available: http://dx.doi.org/10.1021/acs.jpca.5b06020.Sponsors
King Abdullah University of Science and TechnologyThe Petroleum Institute University and Research Center[GRC014]
Publisher
American Chemical Society (ACS)PubMed ID
26334187ae974a485f413a2113503eed53cd6c53
10.1021/acs.jpca.5b06020
Scopus Count
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