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Reactive intermediates of the reduction of SO 2 on activated carbon
Author(s) -
Humeres Eduardo,
Peruch Maria da Gloria B.,
Moreira Regina F. P. M.,
Schreiner Wido
Publication year - 2003
Publication title -
journal of physical organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.325
H-Index - 66
eISSN - 1099-1395
pISSN - 0894-3230
DOI - 10.1002/poc.673
Subject(s) - chemistry , sulfur , carbon fibers , reagent , reactive intermediate , sulfone , sulfide , inorganic chemistry , sulfoxide , kinetics , activated carbon , carbon disulfide , redox , organic chemistry , catalysis , composite material , materials science , physics , adsorption , quantum mechanics , composite number
The reduction of SO 2 on activated carbon was studied in the range of 600–700°C in a differential reactor under steady‐state conditions and under chemically controlled kinetics. Initial rates of carbon conversion and gas reagent were calculated from the mass balance of the gaseous products. The kinetics was first‐order with respect to carbon and first‐order with respect to the partial pressure of SO 2 . The activation parameters were Δ H ≠ = 21.5 kcal mol −1 and Δ S ≠ =−211 cal mol −1 K −1 . The activated carbon was ca. 10 5 times more reactive than graphite, and determined by the enthalpy of activation. The main reaction products were CO 2 and sulfur. CO and COS were produced from consecutive reactions of the primary products. During the pre‐steady state, the sulfur content of the carbon increased to a plateau where the reaction reached the steady state condition. This sulfur was shown to be chemically bound to the carbon matrix and represents the stable reactive intermediates of the reduction of SO 2 . The XPS spectrum of the residual carbon C(S) showed two forms of sulfur bound to carbon: non‐oxidized sulfur (sulfide and/or disulfide) and oxidized sulfur (sulfone, sulfoxide, sulfenate, sulfinate). The sulfur intermediates C(S) reacted with SO 2 at the same rate as pure activated carbon and with CO 2 to produce SO 2 by the reverse reaction. The reaction of C(S) with CO produced COS. Copyright © 2003 John Wiley & Sons, Ltd.