Abstract
Absorption-based CO2 capture technologies face economic feasibility concerns due to the exceedingly high energy requirements of solvent regeneration. Among various proposed solutions, solid acid-aided solvent regeneration stands out as a promising approach. Studies have shown that solid materials containing Lewis and Brønsted acid sites can facilitate deprotonation of protonated amine and breakdown of carbamate molecules, which significantly increases CO2 desorption rate and decreases regeneration energy of common solvents such as MEA and DEA. However, the influence of solid acids on alternate solvents such as amino acids is not well known. Here, we report the performance of TiO2 for the regeneration of CO2-loaded aqueous potassium sarcosinate (K-Sar) solvent. K-Sar is an environmentally friendly amino-acid salt that provides high CO2 absorption rates, making it a good candidate for both point-source and direct-air capture. TiO2 is hydrothermally stable and contains high surface acid site concentration. Desorption of CO2 from K-Sar starts at room temperature in the presence of TiO2, while such onset temperature is greater than 70 °C for regeneration without TiO2. At a temperature of 95 °C, the maximum CO2 desorption rate and cumulative CO2 removal increase by 128 % and 91 %, respectively, in the presence of TiO2 compared to the no TiO2 case. The total regeneration energy could be reduced by ∼ 50 % with TiO2, showcasing the significant role this process can take in improving the commercial competitiveness of absorption-based CO2 capture. Further characterization with XRD, SEM, and NMR concluded that neither the TiO2 powder nor the solvent undergoes any physical or chemical degradation in the regeneration process, suggesting the potential of their long-term usability.
