Synthesis of size-tuneable CO2-philic imprinted polymeric particles (MIPs) for low-pressure CO2 capture using oil-in-oil suspension polymerisation

Highly selective molecularly imprinted poly[ acrylamide-co-(ethylene glycol dimethacrylate)] polymer particles (MIPs) for CO2 capture were synthesized by suspension polymerization via oil-in-oil emulsion. Creation of CO2-philic, amide-decorated cavities in the polymer matrix led to a high affinity to CO2. At 0.15 bar CO2 partial pressure, the CO2/N2 selectivity was 49 (corresponding to 91% purity of the gas stream after regeneration), and reached 97 at ultralow CO2 partial pressures. The imprinted polymers showed considerably higher CO2 uptakes compared to their nonimprinted counterparts, and the maximum equilibrium CO2 capture capacity of 1.1 mmol g−1 was achieved at 273 K. The heat of adsorption was below 32 kJ mol−1 and the temperature of onset of intense thermal degradation was 351−376 °C. An increase in monomer-to-cross-linker molar ratio in the dispersed phase up to 1:2.5 led to a higher affinity toward CO2 due to higher density of selective amide groups in the polymer network. MIPs are a promising option for industrial packed and fluidized bed CO2 capture systems due to large particles with a diameter up to 1200 μm and irregular oblong shapes formed due to arrested coalescence during polymerization, occurring as a result of internal elasticity of the partially polymerized semisolid drops.