Core–shell magnetic zinc-based molecularly imprinted polymer: a robust heterogeneous catalytic nanoreactor toward the CO2 fixation reaction

Abstract

In this work, a core–shell magnetic zinc-based molecularly imprinted polymer (M-Zn-MIP) nanoreactor was fabricated via the precipitation free-radical polymerization process, and its catalytic activity was explored in the CO₂ fixation reaction for the synthesis of cyclic carbonate derivatives. In order to produce a core–shell M-Zn-MIP nanoreactor, reaction components including vinyl-functionalized Fe₃O₄@SiO₂ as a core, zinc methacrylate (ZnMA) as a dimerized metal agent, methacrylic acid (MAA) as a functional monomer, 4-(phenoxymethyl)-1,3-dioxolan-2-one (PMDO) as a template, and ethylene glycol dimethacrylate (EGDMA) as a cross-linking agent participated in the precipitation radical polymerization. The synthesized M-Zn-MIP catalyst was characterized through FT-IR, VSM, BET, FE-SEM, XRD, ICP-OES, TEM, TGA, EDX, and DLS. The created selective sites by the template in the polymeric shell permit the M-Zn-MIP nanoreactor to catalyze the reaction directly and control reactants toward producing the target molecule. The results prove the efficiency of the catalytic nanoreactor in synthesizing cyclic carbonate derivatives via CO₂ fixation reaction with high CO₂ adsorption capacity (Q_m = 22.42 cm³ g⁻¹ under a low external gas pressure of 1 bar at 273 K). This facile catalytic approach has a simple setup, and the heterogeneous catalyst is easily separated with an external magnetic field without tedious filtration and purification. Meanwhile, the M-Zn-MIP nanoreactor exhibited excellent catalytic recyclability and was reused for several runs with negligible efficiency loss.