Carbon Based CO₂ Adsorbent Was Prepared By Co-carbonization Of ZIF-8 And Biomass

Porous carbon material is a kind of carbon material with porous structure,which has high specific surface area,good electrical conductivity and thermal stability,controllable physicochemical properties and so on.It shows great application prospects in the fields of catalysis,adsorption and separation,energy storage and conversion.While biomass-derived carbon,as a special material in porous carbon,has a wide range of raw material sources,most of the biomass-derived carbon that has been reported so far has lost part of its nitrogen content due to high-temperature activation,and it is difficult to ensure proper pore size distribution by high-temperature activation.In order to have efficient CO₂ adsorption,protecting the content of N element when preparing biomass-derived carbon is an important research topic.MOFs-based porous carbon has a pore structure similar to the MOFs precursor,so introducing an appropriate pore structure into the biomass-derived carbon can significantly improve the adsorption capacity.In this work,ZIF-8 was selected as the precursor based on its good pore structure.In addition,the ligand molecule imidazole of ZIF-8 is rich in N,which helps to adsorb CO₂.Grapefruit peel has a natural 3D structure and thus can be used as a modified physical cross-linking point.ZIF-8 was anchored on the surface of the biomass grapefruit peel through electrostatic interaction and in-situ binding,and then ZIF-8-based biomass-derived carbon was successfully prepared through co-carbonization and chemical activation methods.The adsorption capacity of CO₂ of this derivatized carbon is 5.51 mmol/g at 1 bar and 25℃,and exhibits a certain stability after 8 cycles.Cellulose is the most abundant natural polymer compound in the world,and it is a good renewable substrate.To better investigate the factors affecting the adsorption of CO₂ on porous carbon materials,we co-carbonized cellulose and ZIF-8.The OH rich in cellulose can generate a large number of hydrogen bonds in solution with intermolecular forces to weave a dense network structure.The interstitial pores formed by the assembly between this network structure and the carrier facilitate the formation of multi-level pores,which contribute to the adsorption of CO₂.We investigated the effect of ZIF-8 crystal size and co-charring temperature to regulate the CO₂ adsorption capacity.The CO₂ adsorption capacity of this porous carbon is2.83 mmol/g at 1 bar and 25°C.It is finally confirmed that the combination of size effect and carbonization temperature can synergistically affect the CO2 adsorption capacity of porous carbon materials.Our research provides a new idea for CO2 capture and sequestration technology.