CARBONATE EUTECTIC PROMOTED MGO BASED ABSORBENTS FOR CO2 REMOVAL AT 300-400°C

摘要

For control of greenhouse gas emissions, CO2 in syngas generated by gasification of coal or biomass should be captured. The capture of CO2 at warm temperatures provides an advantage in thermal efficiency compared to cooling the gas to liquid absorbent temperatures and reheating to the temperature of use. The subsequent water gas shift reaction can be used to adjust the H2/CO ratio or for hydrogen production. By capturing CO2 during the shift reaction, the equilibrium conversion of CO can be increased, and capturing CO2 at this point allows more total CO2 to be captured. Especially attractive would be a combined bed that contained both CO2 capture material and water gas shift catalyst. In order to capture CO2 in the warm temperature range (250-350°C), solid materials are indicated, and absorbents based on MgO are the most appropriate for this temperature range according to thermodynamic considerations. However, the kinetic rate for direct conversion of MgO to MgCO3 on exposure to CO2 is quite slow.