Molecular Imprinting as a Tool for Exceptionally Selective Gas Separation in Nanoporous Polymers.

Abstract

The alarming increase in atmospheric CO2 levels, driven by fossil fuel combustion and industrial processes, is a major contributor to climate change. Effective technologies for selective CO2 removal are urgently needed, especially for industrial gas streams like flue gas and biogas, which contain impurities such as N2 and CH4. In this study, we designed and synthesized molecularly imprinted polymers (MIPs) using 4-vinylpyridine(4VP) and methacrylic acid(MAA) as functional monomers, and thiophene(Th) and formaldehyde(HC) as molecular templates. The MIPs were engineered to create selective molecular cavities within a nanoporous polymer matrix for efficient CO2 capture. By adjusting the molar ratios of the template to the functional monomers, we optimized the imprinting process to enhance CO2 selectivity over N2&CH4. The resulting MIPs exhibited excellent performance, achieving a maximum CO2/N2 selectivity of 153 at 25 bar and CO2/CH4 selectivity of 25.3 at 1 bar, significantly surpassing previously reported porous polymers and metal-organic frameworks(MOFs) under similar conditions. Heat of adsorption studies confirmed the strong and selective interaction of CO2 with the imprinted cavities, demonstrating the superior adsorption properties of the synthesized MIPs. This study highlights the potential of molecular imprinting for improving CO2 capture capacity and selectivity, offering a scalable solution for industrial CO2 separation.