Effect of coal type on the physical properties and CO 2 adsorption performance of activated coke prepared by a single-step method under flue gas atmosphere

Abstract Activated coke is considered to be one of the promising CO2 adsorbents. It could be prepared using coals by a single-step method, but the physical properties and CO2 adsorption performance of activated coke were significantly different when using different ranks of coals. In this study, six typical coals covering lignite, sub-bituminous coal, bituminous coal and anthracite were selected to prepare powdered activated coke (PAC) by a single-step method under flue gas atmosphere. The pore structure, surface morphologies and surface functional groups of the prepared PACs were characterized and the yield was calculated. The CO2 adsorption performance and adsorption selectivity for CO2 / N2 was experimented and analyzed. Results show that the PAC prepared from lignite had the maximum specific surface area of 479 m2/g, the most abundant oxygen-containing functional groups and the highest CO2 adsorption capacity of 3.35 mmol/g at 0°C and 1.2 bar, but the yield of 48.41% was slightly less than others. Then followed by the PAC prepared from sub-bituminous coal. For PACs prepared from bituminous coal, the specific surface area, oxygen-containing functional groups and CO2 adsorption capacity were all decreased and greatly affected by the caking property. The PAC prepared from strong-caking coal, such as Xinwen coal, was unsuitable for PAC preparation. The PAC prepared from anthracite had the similar physical properties and CO2 adsorption performance with PAC prepared from medium-caking bituminous coal, but the yield of 72.17% was the most. Moreover, the prepared PACs presented good adsorption selectivity for CO2 / N2, which indicated the feasibility in practical applications. These conclusions could provide references for preparation of PACs using coals as the raw materials by the single-step method under flue gas atmosphere.