Preparation And Modification Of Porous Carbon For CO₂Adsorption

Global warming is threatening the living environment of human beings. As a major green house gas, carbon dioxide (CO2) and its adsorption and separation has brought public attention. Adsorption method has the advantages of low energy cost, easy separation process, and has been an effective separation method. The key point of adsorption process is the design and preparation of adsorption materials. Present adsorption materials are wished to be improved from the perspectives of adsorption capacity, selectivity, adsorption kinetics, etc. Basing on physical activation method to make porous carbon materials, the third chapter of this paper, we prepared a series of coconut shell-based porous carbon under various operation conditions such as activation temperature and water content, we also conducted CO2static adsorption test to study the plat-based activated carbon’s adsorption behavior of CO2. The forth chapter focused on design of porous adsorption materials oriented by phenolic amine, and prepared macroporous-mesoporous-microporous containing N-doping nanocarbon monolith. It also improved the sorts and amounts of nitrogen-containing functional group on surface of the material via ammoniation. The ionic liquid is a molten salt with wide liquid path and low saturated vapor pressure, we used basic ionic liquid to load on the pore structures, aiming at improving the adsorption rate.The carbon material obtained through direct carbonization of coconut shell possessed relative low specific surface area and pore volume. We obtained coconut shell-based activated carbon with high specific surface area and pore volume through carbonization-activation in one step method. The specific surface area and pore volume can be controlled by adjusting activation temperature and water content. The static CO2adsorption test shows an adsorption capacity of2.57-3.08mmol g-1under25℃. The activation conditions could affect pore structure which determined the CO2adsorption capacity of the materials. Study shows that the prepared coconut shell-based activated carbon possessed a relative high adsorption capacity when activating temperature is as high as800℃, water content is0.05mL/min, and activation duration is up to60min.Guided by hydrogen bonding assembly process, we obtained nitrogen-containing carbon monolith with hierarchical macroporous-mesoporous-microporous structure, the carbon materials have different nitrogen content by adjusting the quantity of the amine, we conducted amination process to polymers and carbon monolith after carbonization of the polymers under phenolic amine system, improved the content of the nitrogen-containing functional group on carbon monolith, the static adsorption amount of CO2has increased by22%. Finally we came to the conclusion that low nitrogen content contributes little to the change of CO2adsorption capacity; when nitrogen content of the material increases, the change of pore structure has a great impact on the CO2adsorption.The basic ionic liquid layer loaded on the pore structure can improve the transfer of CO2in the pore structure basing on the weak alkalinity of ionic liquid. The experiment shows that [BMIM]BF4ionic liquid can improve the apparent adsorption rate. However, the adsorption capacity decreased resulting from the blocking of some micropores.