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Kinetics and reaction mechanism of catalytic oxidation of low concentrations of hydrogen sulfide in natural gas over activated carbon
Author(s) -
Dalai Ajay K.,
Tollefson Eric L.
Publication year - 1998
Publication title -
the canadian journal of chemical engineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.404
H-Index - 67
eISSN - 1939-019X
pISSN - 0008-4034
DOI - 10.1002/cjce.5450760507
Subject(s) - chemistry , catalysis , hydrogen sulfide , sulfur , activated carbon , kinetics , partial pressure , adsorption , oxygen , hydrogen , reaction rate , reaction mechanism , chemical kinetics , sulfide , inorganic chemistry , carbonyl sulfide , claus process , carbon fibers , materials science , organic chemistry , physics , quantum mechanics , composite number , composite material
The kinetics of the hydrogen sulfide oxidation process, producing mostly sulfur and water, was studied using 0.25 to 1.0 g Hydrodarco activated carbon catalyst and varying the O 2 /H 2 S ratio (molar basis) in the feed gas between 0.5 to 0.6 in the temperature, and pressure ranges from 125 to 200°C and 225 to 780 kPa. SO 2 was obtained as an undesirable by‐product during H 2 S oxidation reaction or as a product during regeneration of the catalyst. The feed gas contained 0.9 — 1.3 mol% H 2 S with approximately 80 mol% CH 4. In this paper, the factors affecting the H 2 S conversion and SO 2 formation are presented. The rate expressions for (a) H 2 S conversion and (b) SO 2 formation were developed from the Langmuir‐Hinshelwood surface control reaction model. The experimental data were well correlated by the rate equations. Also, the rate parameters were evaluated and correlated with temperature. The activation energies for H 2 S oxidation and SO 2 production reactions were calculated to be 34.2 and 62.5 kJ/mol, respectively. Partial pressures of oxygen and H 2 S were found to influence H 2 S conversion whereas, the presence of water in the feed gas up to 10.5 mol% did not affect H 2 S conversion significantly. Heats of adsorption for various species on the active sites were calculated. SO 2 production was, as expected, enhanced at higher temperature, and its rate was much smaller than the oxidation rate of H 2 S under the reaction conditions used.