Combustion of fossil fuels, industry and agriculture sectors are considered as the largest emitters of carbon dioxide. In fact, the emissions of CO2 high reactivegreenhouse gas have has risen been intensifying considerably in during the last two decades, which has led to air pollutionresulting in global warming and affected negativelyinducing the variety of adverse human health effects on human and the environment. Calling for effective and green feedstocks to remove CO2, low-cost materials, such as coal ashes “wastes-to-materials”, have been considered among the interesting options candidates for of CO2 capture technologies. On the other handTo address this concern, several techniques using including coal ashes as in organic supports (e.g., catalytic reduction, photocatalysis, gas conversion, ceramic filter, gas scrubbing, adsorption, etc.and so on) have been widely applied to reduce CO2 to methane.. These processes are among the most efficient solutions applied utilized by industries and scientists to minimize the amount ofproduce clean energy from the released CO2 and limit its continuous emissions into the atmosphere. Here, we review the recent trends and advancements in the applications of coal ashes including coal fly ash and bottom ash as low-cost wastes to reduce control the CO2 concentration using through adsorption and catalysis processes. Chemical The chemical routes of structural modification and characterization techniques of coal ash-based feedstocks are also discussed in details. Then, t adsorption and catalytic he performance of the coal ashes derivatives in towards CO2 adsorption and its catalytic conversion inselective reduction to CH4 are also described. The main objectives of this review isare to highlight the high-efficiencyexcellent capacity of the coal ash-based adsorbentsaforementioned materials to capture and selective conversion of remove CO2 and catalysts to convert this gas into CH4methane, which limitswith the aim of minimizing coal ashe
