Thermodynamics and kinetics analysis of Ca-looping for CO2 capture: Application of carbide slag

Abstract

The calcium looping process, which is based on the calcination/carbonation of CaCO3, has emerged over the years as a recommended low cost technology for post-combustion CO2 capture. In this work, a novel Ca-based material (carbide slag) is proposed for CO2 capture through the Ca-looping method. Carbide slag is a by-product generated in the process of acetylene production, and its main components are Ca(OH)2 and CaCO3. In this work, CO2 was chemisorbed by CaO solid particles derived from precalcination of inexpensive and widely available carbide slag. The reaction mechanism was investigated by the thermodynamics software-FactSage and by Thermogravimetric Analysis-Differential Thermal Analysis (TG-DTA). The study found that the temperature of CO2 capture should be more than 650 °C and lower than 900 °C. Moreover, the carbide slag showed good stability for over 20 cycles of calcination/carbonation. Further, the kinetics of calcination/carbonation were investigated by the Kissinger method, Flynn-Wall-Ozawa (FWO) method and Coats-Redfern method. The results of this work indicate that carbide slag is a suitable material for CO2 capture by Ca-looping technology, which would be very helpful for carbide slag resource utilization.