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

Abstract

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 liquidphase 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 carbonbased 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 crosslinking 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.

Perspectives of Engineered Biochar for Environmental Applications: A Review

“…The biochar surface functional groups have specific distribution characteristics. For example, nitrogen-containing basic functional groups are mostly distributed in micropores, while polar oxygen-containing acidic functional groups are mainly distributed in mesopores and macropores, and oxygen-containing nonpolar functional groups are mostly present on the surface of multilayer pores. , The generation of macropores and mesopores in biochar structures is advantageous for the transportation process of the adsorbate, and the presence of micropores can serve as adsorption sites for small adsorbates (e.g., CO 2 ) . Activation methods are divided into physical activation (thermal oxidation), chemical activation, and integration of both methods. , …”

“…216,217 The generation of macropores and mesopores in biochar structures is advantageous for the transportation process of the adsorbate, and the presence of micropores can serve as adsorption sites for small adsorbates (e.g., CO 2 ). 218 Activation methods are divided into physical activation (thermal oxidation), chemical activation, and integration of both methods. 219,220 3.1.1.…”

“…Unique properties of biochar, such as porous structure, high surface area, and plenty of specific functional groups, make it useful for the adsorption of gases. Worldwide a large amount of CO 2 is generated due to burning fossil fuels and human activity, resulting in global warming and threatening humankind and the environment. , Over the past few years, heterogeneous solid adsorbents such as microporous zeolites, carbon-based materials, and ordered mesoporous silicas have been studied for CO 2 capture. Carbon-based materials as cost-effective adsorbents have received more attention than other adsorbents because carbon-based adsorbents usually have high chemical and thermal durabilities, tunable pore architectures, and tolerances to water moisture .…”

Efficient and Stable Ni/ZSM-5@MCM-41 Catalyst for CO2 Methanation

“…Atmospheric CO 2 emissions have reached the peak historical average annual concentration of 412.5 ppm in 2020. 1,2 At present, CO 2 emissions are mainly caused by the large-scale burning of fossil fuels such as coal, oil, and natural gas. The total amount of CO 2 emission from the energy industry is large and accounts for a high proportion of it.…”

“…Since the industrial revolution, carbon dioxide (CO 2 ) emissions have continued to increase due to the increasing degree of industrialization, massive consumption of fossil fuels, reduction of worldwide forest area, and continuous change of land use caused by human activities. Atmospheric CO 2 emissions have reached the peak historical average annual concentration of 412.5 ppm in 2020. , At present, CO 2 emissions are mainly caused by the large-scale burning of fossil fuels such as coal, oil, and natural gas. The total amount of CO 2 emission from the energy industry is large and accounts for a high proportion of it.…”