First kinetics verification of the useful H2Ogas inhibition on the thermal regeneration of spent activated carbon in flue gas desulfurization

The dry desulfurization technology of activated coke/carbon (AC) adsorption has been widely applied, especially in the industry that requires the feedstock H2SO4. If the AC consumption or the purity of inert N-2 atmosphere in the unit of AC thermal regeneration could be reduced, the operation cost bottleneck of AC technology can be relieved. This work conducted a serial of temperature-programmed experiments with heating rate 2 K/min to clarify the thermal regeneration of spent activated carbon in flue gas desulfurization, focusing on the dominant reaction between adsorbed H2SO4 and carbon: 2H(2)SO(4) + C -> CO2 + 2H(2)Ogas + 2SO(2). The reaction started at similar to 441 K and completed at similar to 600 K, while many reports only stated the practical temperature should be 600-723 K in engineering application. When 9.5 % (v/v) water vapor H(2)Ogas was added to the blow atmosphere, the starting temperature increased significantly to 475 K, CO2 output and carbon consumption were reduced by 10.2 % respectively, and apparent activation energy in temperature interval 491-571 K increased by 54.5 % from 84.69 to 130.85 kJ/mol. This work is the first kinetics verification of H(2)Ogas inhibition on the regeneration. Certainly, the inhibition is useful for carbon consumption reduction. The blow atmosphere can contain H(2)Ogas, CO2, but not O-2. If existing a little of O-2 (2-4 %, v/v) in the atmosphere, the oxidization AC to CO2 began obviously at 493-475 K and became more intense after 600 K. This work was done in an overall view, and would be helpful for the application of AC desulfurization.