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.