Amidoximes: promising candidates for CO2 capture

Abstract

Monoethanolamine (MEA) dominates power plant carbon dioxide (CO₂) scrubbing processes, though with major disadvantages such as a 8–35% energy penalty. Here we report that structurally comparable amidoximes are promising CO₂ capture agents based on RIMP2 electronic structure calculations. This was experimentally verified by the synthesis and testing of representative amidoximes for capture efficiencies at pressures as high as 180 bar. Acetamidoxime, which has the highest percent amidoxime functionality showed the highest CO₂ capacity (2.71 mmol g⁻¹) when compared to terephthalamidoxime (two amidoximes per molecule) and tetraquinoamidoxime (four amidoximes per molecule). Polyamidoxime surpassed activated charcoal Norit RB3 for CO₂ capture per unit surface area. Adsorption isotherms exhibit Type IV behavior and acetamidoxime found to increase CO₂ capture with temperature, a less observed anomaly. Porous amidoximes are proposed as valuable alternatives to MEA.