Removal of carbon dioxide from flue gas by ammonia carbonation in the gas phase

The increasing anthropogenic CO₂ emissions and possible global warming have challenged the United States and other countries to find new and better ways to meet the world's increasing needs for energy while, at the same time, reducing greenhouse gas emissions. This study explores the possibility of using ammonium bicarbonate (NH₄HCO₃) formation by ammonia carbonation in the gas phase to achieve reduction of CO₂ emissions from industrial flue gas. Experimental results obtained in this study demonstrate that removal of flue-gas CO₂ can be achieved via formation of solid NH₄HCO₃ through ammonia carbonation in the gas phase. Removal of CO₂ is quantified by monitoring CO₂ concentrations at the entrance and exit of the reactor column. The products of ammonia carbonation were identified by solid-state nuclear magnetic resonance analysis. For the experimental conditions employed in this study, current results show up to 50% removal of CO₂ from the flue gas. Higher efficiencies are likely achievable by optimizing the operating conditions and geometry of the reactor.