Research progress of granulation technique of CO2 adsorbent from coal-fired flue gas

Carbon source emitted by coal-fired flue gas is considered to be one of the main factors for the rapid rise of global CO2 concentration. In order to deal with the climate and environmental problems caused by the massive emission of CO2-based greenhouse gases, countries all over the world have raised low-carbon development as a national strategy. High-temperature CO2 adsorbent capture technology has always been the focus of research in the field of carbon emission reduction and it is also one of the most direct and effective ways to achieve the "dual carbon" goal. CaO-and Li4SiO4-based solid adsorbents are currently the two most common and promising high-temperature CO2 adsorbents. The granulation of sorbent powder is a necessary prerequisite for its industrial circulating fluidization. This paper mainly analyzed and summarized the granulation and molding technology of CaO- and Li4SiO4-based sorbents. The CaO-and Li4SiO4-based adsorbents were classified, summarized and discussed mainly by granulation methods, and the differences in chemical adsorption performance and mechanical strength of sorbent particles were discussed and analyzed. It is concluded through the analysis that the CaO adsorbent particles prepared by mechanical molding usually have higher mechanical strength, but have a certain damage to the original structure of the sorbent and leads to the densification of microstructures, thus affecting the chemical adsorption performance. The chemical adsorption performance of the adsorbent particles prepared by injection molding is better, but its mechanical strength needs to be enhanced because there is no mechanical extrusion process. For Li4SiO4-based high-temperature adsorbents, indirect molding method exhibits more advantages and application prospects because it can avoid the crushing of adsorbent particles caused by the direct granulation process. This paper also discussed the future ideas of granulation and molding of CaO-based and Li4SiO4-based adsorbents, in order to provide assistance for the development and industrial application of high-temperature CO2 sorbent.