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Ind. Eng. Chem. Fundam. 1984, 23, 338-341
Intrinsic Global Rate Constant for the High-Temperature Reaction of CaO with H2S Howard Freund Corporate Research Sclence Laboratories, Exxon Research and Engineering Company, Annandale, New Jersey 0880 1
With the use of a Ca-pretreated, high surface area, amorphous carbon, the CaO-H2S reaction was studied in the temperature range 1400-1700 K. Under these conditbns, the reaction was strongly porediffusion limited. After taking diffusion into account, the global intrlnslc chemical surface reaction rate constant was determined to be 4.93 f 0.81 X 10' exp[(-45500 f 7800)lRT)l g of CaO/cm'-s-atm of H,S.
Introduction The reaction of CaO with H2S is of technical interest in both gasification (Squires, 1970; Moss et al., 1972) and fuel rich combustion systems (Moss et al., 1972; Freund and Lyon, 1982) as the principal sulfur capture reaction when CaO is used as a sulfur sorbent. Earlier TGA work by Squires et al. (1971) determined the overall kinetics of the reaction CaO + H2S + Cas + HzO (1) They observed an activation energy of 23 kcal/mol and reported overall reactivity using the expression
More recently, Simons and Rawlins (1980) have taken data from Keairns et al. (1973) and determined a global intrinsic rate constant. They determined the rate constant to be g/cm2-s-atm at T = 1144 K with an activation energy of only 10 kcal/mol. Both the results by Simons and Rawlins and Squires et al., when extrapolated to temperatures suitable for pulverized coal operation, T > 1400 K, imply that little conversion (
