Functional Biochar Synergistic Solid/Liquid-Phase CO₂ Capture: A Review

Nowadays, global warming is becoming more and more serious, while CO 2 capture technologies have emerged endlessly, with methods of solid-phase CO 2 capture for physical adsorption and liquid-phase CO 2 capture for chemical absorption. Biochar has been widely used to achieve CO 2 sequestration and emission reduction as a result of its wide range of precursor sources, strong adsorption, and rich surface functional groups. It reviews the existing post-combustion CO 2 capture solutions, focusing on the analysis of CO 2 capture technologies based on liquid-phase ammonia/monoethanolamine and solid-phase carbon-based materials. The former (liquid phase) is with limitation of capture efficiency as a result of strong volatility and thermal degradation, while the latter (solid phase) is accompanied by limited CO 2 /N 2 selectivity. The realization of synergy between the two would “learn from each other’s strengths” to improve the CO 2 adsorption ability. The review puts forward the concept of “biochar-functionalized cross-linking synergistic ammonia CO 2 capture technology”, which not only broadens the idea of multi-level utilization of biochar, significantly improving the liquid-phase (ammonia) CO 2 capture efficiency, but also has practical significance for the utilization of biomass waste and reduction of CO 2 emissions.