Performance and Mechanism Analysis of TiO₂-Modified Cross-Linked Resin in the Process of CO₂ Capture

Amine-functionalized resins hold significant promise for CO₂ capture applications, yet their practical deployment is impeded by inherent amine group degradation and inadequate cyclic stability. Herein, a TiO₂-modified TEPA-supported spherical composite (TEPA-TiO₂@SCPS) was synthesized via a sol-gel method, where TiO₂ nanoparticles enhance structural stability and promote electron transfer, leading to improved amine retention and CO₂ adsorption. Systematic characterization including elemental analysis, XPS, SEM, and XRD coupled with cyclic adsorption-desorption tests demonstrates that TiO₂ modification markedly mitigates amine group loss over 10 consecutive cycles. Specifically, the CO₂ adsorption capacity of TEPA-TiO₂@SCPS exhibited a 1.5% decrease relative to its initial value (compared to 3.8% for TEPA@SCPS), with the nitrogen retention rate enhanced from 81.5 wt % to 91.4 wt %. DFT calculations further corroborate that TiO₂ lowers the CO₂ adsorption energy barrier by 53.2%, from 7.55 to 3.53 eV, and facilitates reversible proton transfer via sulfate ion-mediated hydrogen bonding networks. The molecular-level mechanism underlying TiO₂-modulated amine reactivity and structural stability is revealed, which provides a viable strategy for developing amine-based CO₂ adsorbents capable of long-term cyclic operation in practical capture systems.