Removal of CO2 in a multi stage fluidised bed reactor by monoethanolamine impregnated activated carbon

Abstract

ABSTRACT The increase of carbon dioxide (CO2) concentration in the atmosphere leads to global warming and climate change. To mitigate the emission of CO2, we have developed and designed a four stage fluidised bed reactor and it was operated in a continuous counter-current manner. The adsorbents used for this fluidised bed reactor were monoethanolamine impregnated activated carbon (MEA-AC) of different impregnation (0.2,0.4 and 0.6) and activated carbon (AC) prepared from green coconut shell. Changing the three hydrodynamics factors like gas velocity, solid flow rate and weir height, the maximum % removal of CO2 has been found out. Sampling and analysis has been performed by using Orsat apparatus. The percentage (%) removal of CO2 by AC was minimum due to only physical adsorption of CO2. MEA-AC, having highest impregnation ratio (0.6) shows maximum % removal of CO2 because MEA is of less viscous, Stable carbamate ion formed because of the –I effect of one alcohol groups during the reaction of CO2 with MEA-AC that leads to more adsorption. The higher impregnation ratio leads to more removal of CO2 because more amine functional groups are present in the AC surface. Both physical adsorption as well as chemical adsorption occurs in MEA-AC. The maximum % removal of CO2 for MEA-AC (0.6) was 94.9%, under the solid flow rate of 4.12 kg/h, superficial gas velocity of 0.188 m/s and the weir height of 50 mm.