Preparation Of Mesoporous Carbon Materials And Its Application On CO₂ Storage In The Presence Of Water

CO₂ is the main greenhouse gas causing the greenhouse effect.In recent years,with the incrseaing demand for energy in the human society,the consumption of fossil fuels is increased.As a result,huge amounts of CO₂ has been emitted.How to reduce CO₂ emissions effectively has attracted the whole world's attention.CO₂ capture and storage is one of the most effective means of reducing CO₂ content.Adsorption,which has the advantage of low energy consumption,simple equipment,wide operating temperature and pressure range is the most effective way to capture and store CO₂.Gas hydrate is a potential technique for CO₂ capture and storage.A novel method is presented in this work to improve the adsorption capacity of CO₂ which comprises both adsorption and gas hydrate technology together.Mesoporous carbon materials were obtained using hard-template and soft-template method respectively,which were characterized by N2 adsorption isotherm,XRD,SEM and TEM.The results showed that the specific surface area and pore volume of CMK-3 synthesized via hard-template method were 1115 m2/g and 1.11 cm3/g,average pore diameter of CMK-3 was 3.25 nm.The specific surface area and pore volume of mesoporous carbon synthesized via soft-template method were optimal,1300 m2/g and 1.61 cm3/g respectively under the conditions of mass ratio of synthesis reactions was TEOS: resol: HCl: F127 = 2.08: 2.5: 1: 1 and the concentration of hydrochloric acid was 0.2 M.The average pore diameter was about 8 nm.Hard template method can obtain ordered mesoporous structure,while the soft template method can not obtain ordered mesoporous structure.Adsorption of CO₂ gas has been significantly improved when the mesoporous carbon was pre-adsorbed water.The CO₂ adsorption amount of pre-adsorbed water CMK-3 was up to 42 mmol/g,the CO₂ adsorption capacity of mesoporous carbon prepared by soft template method was as high as 51.8 mmol/g.And in the dry state,their adsorption capacity for CO₂ were 18.2 mmol/g and 28 mmol/g respectively.CO₂ adsorption capacity is significantly increased because,under the conditions of the pre-adsorbed water,not only the formation of carbon dioxide hydrate but also still partially porous physical adsorption of CO₂,in addition,a certain amount of CO₂ can also be dissolved in water.In the CMK-3,when 275 K,the carbon dioxide hydrate generating pressure was 2.05 MPa,and the soft template mesoporous carbon hydrate formation pressure of 1.75 MPa,which is due to the small pore size of CMK-3,therefore requiring a higher pressure.Soft template mesoporous carbon loading of CO₂ has a high storage capacity,when loading density was 0.3 g/cm3,its gas storage capacity can reach 269.03 V/V,loop experiments show that this storage method has good cycling stability.