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CaC2 production is studied from the viewpoint of thermodynamics using an equilibrium composition model with total Gibbs free energy minimization. It is found that CaC2 is formed directly from the reaction of C and CaO without an intermediate step under the conditions of industrial practice. The different reaction mechanisms reported in the literature can be attributed to the difference in reaction conditions. The model determines equilibrium composition of the reaction system under various conditions, including those applicable to the autothermal CaC2 production process.

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Carbon-based materials have been used for SO 2 removal from flue gases for several decades. In this process, SO 2 is captured by storing in the pores of carbons in the form of H 2 SO 4 , and regeneration of the SO 2 -captured materials is necessary to recover SO 2 capture ability. V 2 O 5 -supported activated coke (V 2 O 5 /AC) has been reported to be highly active for SO 2 removal, and its regeneration has been investigated from the viewpoint of the reaction mechanism. This work studied the regeneration kinetics with the aid of a thermogravimetric analyzer coupled with a mass spectrometer. The SO 2 -captured sample was prepared in a fixed-bed reactor with a simulated flue gas containing 1500 ppm of SO 2 , 5% O 2 , and 5% H 2 O. The kinetic equation was obtained by fitting the H 2 SO 4 conversion (α) at different heating rates with nonisothermal kinetic methods called Flynn−Wall− Ozawa and Coats−Redfern. The results indicated that the regeneration kinetic behavior varies with α. At α = 0.1−0.4, regeneration follows first-order reaction model f(α) = 1 − α with an activation energy of about 85.7 kJ/mol. At α = 0.5−0.8, regeneration follows three-dimensional diffusion model f(α) = 1.5(1 − α) 2/3 [1 − (1 − α) 1/3 ] −1 , with the activation energy increasing from 88.9 kJ/mol at α = 0.5 to 112.1 kJ/mol at α = 0.8.

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