Performance and Mechanism Analysis of TiO ₂ -Modified Cross-Linked Resin in the Process of CO ₂ Capture

Amine-functionalized resins hold significant promise for CO 2 capture applications, yet their practical deployment is impeded by inherent amine group degradation and inadequate cyclic stability. Herein, a TiO 2 -modified TEPA-supported spherical composite (TEPA-TiO 2 @SCPS) was synthesized via a sol–gel method, where TiO 2 nanoparticles enhance structural stability and promote electron transfer, leading to improved amine retention and CO 2 adsorption. Systematic characterization including elemental analysis, XPS, SEM, and XRD coupled with cyclic adsorption–desorption tests demonstrates that TiO 2 modification markedly mitigates amine group loss over 10 consecutive cycles. Specifically, the CO 2 adsorption capacity of TEPA-TiO 2 @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 TiO 2 lowers the CO 2 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 TiO 2 -modulated amine reactivity and structural stability is revealed, which provides a viable strategy for developing amine-based CO 2 adsorbents capable of long-term cyclic operation in practical capture systems.