Synthesis of Size-Tunable CO_2-Philic Imprinted Polymeric Particles (MIPs) for Low-Pressure CO_2 Capture Using Oil-in-Oil Suspension Polymerization

摘要

Highly selective molecularly imprinted poly- [acrylamide-co-(ethylene glycol dimethacrylate)] polymer particles (MIPs) for CO_2 capture were synthesized by suspension polymerization via oil-in-oil emulsion. Creation of CO_2-philic, amide-decorated cavities in the polymer matrix led to a high affinity to CO_2. At 0.15 bar CO_2 partial pressure, the CO_2/N_2 selectivity was 49 (corresponding to 91% purity of the gas stream after regeneration), and reached 97 at ultralow CO_2 partial pressures. The imprinted polymers showed considerably higher CO_2 uptakes compared to their nonimprinted counterparts, and the maximum equilibrium CO_2 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 ℃. An increase in monomer-to-cross-linker molar ratio in the dispersed phase up to 1:2.5 led to a higher affinity toward CO_2 due to higher density of selective amide groups in the polymer network. MIPs are a promising option for industrial packed and fluidized bed CO_2 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.