Enhanced adsorption of trace carbon dioxide from acetylene using Polyethyleneimine-Diethanolamine blends

The removal of trace carbon dioxide (CO2) from acetylene (C2H2) through adsorption poses a significant challenge due to their similar kinetic diameters and physical properties. Here, we report a novel solid amine adsorbent, polyethyleneimine-diethanolamine functionalized silica dioxide (termed P/D-SD), which exhibited a remarkable CO2 adsorption capacity of 1.76 mmol/g at 298 K and 0.0004 bar. The IAST selectivity of the CO2/C2H2 (1/99, v/v) mixture of P/D-SD was 7.98E + 05. The exceptional separation performance of P/D-SD is demonstrated through breakthrough experiments, producing ultra-high purity C2H2 (greater than 99.9 %) from CO2/C2H2 (1/99) mixtures. Its CO2 adsorption performance remains largely unaffected under different humidity condition. Furthermore, P/D-SD exhibited excellent stability in the adsorption–desorption cycle and rapid CO2 adsorption kinetics at different temperatures when compared with P-SD. The adsorption mechanism of P/D-SD with CO2 was studied as a chemisorption process via in situ DRIFTS.