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

ABSTRACT

The increase of carbon dioxide (CO₂) concentration in the atmosphere leads to global warming and climate change. To mitigate the emission of CO_2, 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 CO_2. 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.

KEYWORDS:

• Monoethanolamine
• activated carbon
• adsorbent
• carbon dioxide
• multistage fluidised bed
• impregnation
• counter-current
• Zwitterion

Disclosure statement

No potential conflict of interest was reported by the authors.