Kinetics of CO2 Gasification of Alkaline Black Liquor from Wheat Straw. 2. Evolution of CO2 Reactivity with the Solid Conversion and Influence of Temperature on the Gasification Rate

Results obtained in recent studies have shown that black liquor (BL) gasification can be considered as an attractive recovery system. However, limited information has been published on the gasification kinetics of alkaline BL char (ABLC). Part 1 of this work (Gea, G.; Sanchez, J. L.; Murillo, M. B.; Arauzo, J. Ind. Eng. Chem. Res. 2004, 43, 3233) studied the CO2 gasification of ABLC, specifically the influence of [CO] and [CO2] on the gasification rate at different temperatures. The present work is focused on the variation of this reaction rate with solid conversion during the gasification process. The results obtained show that the gasification rate increases with the solid conversion up to a maximum value and then decreases. The effect of various factors such as pyrolysis operating conditions on this variation has also been analyzed. Furthermore, the dependence of the ABLC gasification rate on the temperature has been evaluated, and the apparent average activation energy over the range 170-234 kJ/mol has been determined for the temperature range 750-850 (degree)C.