Facilely Synthesized M-Montmorillonite (M = Cr, Fe, and Co) as Efficient Catalysts for Enhancing CO2 Desorption from Amine Solution

Catalytic amine regeneration has recently emerged as an effective strategy to improve CO2 desorption at low temperatures. In this work, we synthesized inexpensive M-montmorillonite (M = Cr, Fe, and Co) catalysts via a facile metal ion-exchange process and used these to optimize the CO2 desorption rate of a 30 wt % monoethanolamine (MEA) solution at a moderate temperature (∼86 °C). The metal ion-exchange process led to Si and Al leaching from the aluminosilicate layers and cation removal from the Mont interlayers, resulting in an increase in the surface acidity, mesoporosity, and total surface area of the ion-exchanged Mont catalysts. The prepared catalysts introduce acid sites to amine solution that can attach with the carbamate, carbonate, and bicarbonates, to favor the CO2 desorption at low temperatures. Overall, the CO2 desorption rate and the total amount of released CO2 were improved up to 315 and 82.5%, respectively, whereas the regeneration energy penalty was reduced by 40%, in comparison with the noncatalytic MEA solution. The impact of various physicochemical catalytic properties on the CO2 desorption performance was also evaluated. The stability of the prepared catalysts was verified in five cyclic uses and no change in the catalytic activity or structure was detected. In addition, the catalysts were readily separable by simple filtration. This work introduces an effective strategy to design abundant and cost-effective catalysts for energy-efficient CO2 capture.