The role of oxygen vacancy in CaO-Ca12Al14O33 materials derived from hydrocalumite for enhanced CO2 capture cyclic performance

Abstract

The cyclic performance of calcium-based sorbents plays a critical role in attaining efficient carbon dioxide capture, a vital issue for the advancement of related techniques. This study presents an investigation into the synergistic mechanism that governs the cycling performance of CaO-Ca12Al14O33 materials obtained through thermal treatment of the hydrocalumite. A ball milling method was used to prepare a calcium-based material with a hydrotalcite structure, and the microstructure of the composites was analyzed by X-ray diffraction, scanning electron microscopy, transmission electron microscopy and the Brunauer–Emmett–Teller. The role of oxygen vacancies in contributing to a diffusion-controlled kinetic limitation, along with the development of the composites' microstructure, was achieved through the assistance of density functional theory calculations, electron paramagnetic resonance and X-ray photoelectron spectroscopy. In addition, The CO2 capture performance and cycling stability were analyzed under 650 °C adsorption/850 °C desorption conditions, the CaO/Ca12Al14O33 composites showed high equilibrium adsorption and adsorption rates, and the residual conversion after 20 cycles was 3–4 times higher than pure CaO.