An intensified process for CO2 capture from air using the highly soluble methylglyoxal-bis-iminoguanidine (MGBIG) and sarcosine amino acid in aqueous solution has been investigated. The previously reported three-step direct air capture (DAC) process has been replaced with an improved intensified two-step approach that involves simultaneous CO2 absorption and precipitation in the form of crystalline MGBIG carbonate using a household humidifier setup, followed by quantitative regeneration of MGBIG and CO2 release by applying moderate heat (130 °C). The two-step process also eliminates the need to use an inorganic base for the CO2 loading stage compared to the three-step protocol that uses KOH. A variety of crystallization experiments with MGBIG and amino acids were set up to identify the most suitable amino acid/MGBIG combination and the optimal concentrations that maximized the yield of MGBIG carbonate formed and minimized the loss of amino acid through precipitation. Based on these preliminary experiments, intensified DAC cycles were carrying out using the best amino acid/MGBIG combination and optimizing the experimental conditions to maximize the CO2 cyclic capacity.

Intensified direct air capture process combining aqueous bis-iminoguanidine (BIG) and amino acid

ACS Spring 2022

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