Biomass-based Carbon Materials With Tunable Pores For The Adsorptive Separation Of Gas Mixtures

Separation is an indispensable chemical engineering process,however,the efficient separation of gas molecules with extremely similar sizes and properties is a great challenge.The traditional cryogenic separation technology faced with problems of high energy consumption and low economic benefits.In contrast,the adsorption separation is an energy-efficient,simple and highly efficient separation technology,which has attracted enormous attention in the field of gas separation.The key to adsorption separation technology lies in the development of high-efficiency adsorbents.However,the conventional adsorbents have disadvantages such as poor stability,high costs,and difficulty in commercial application.On the contrary,porous carbons have become the subject of extensive research due to its advantages of its good stability,high adsorption capacity,controllable pore structure,and tunable pore surface properties,.Specially,biomass carbon materials have the merits of low-cost and renewable.Therefore,the thesis focuses on the development of facile methods for the preparation of inexpensive biomass-based carbon materials with large surface area,high density of gas binding sites.We have investigated the its adsorption and separation performance of the prepared carbons for sulfur dioxide capturing and acetylene/ethylene/carbon dioxide separation.These works can provide theoretical basis and technological reference for the applications of biomass-derived carbons in the removal of sulfur dioxide and one-step ethylene purification.The biomass waste,camphor seeds husk,was used as raw materials for the preparation of ultramicroporous carbons（CSHs）with large specific surface area.The pore texture property and pore environment of CSHs can be tuned by changing the porogen/biomass ratio.The prepared carbons exhibited large SO₂ adsorption capacity of 20.7 mmol g^-1 and excellent IAST selectivities for SO₂/CO₂（56）,SO₂/CH₄（378）,and SO₂/N₂（9110）at 298 K and 1.0 bar.The dynamic separation experiments further confirmed the excellent performance of the prepared carbons for the adsorption of SO₂ even under aerobic conditionsThe N,O-doped ultramicroporous carbons was further prepared with hydroxylamine hydrochloride as the porogen and N,O sources.The N₂ adsorption isotherms and elemental analysis results indicated that the prepared carbons possess narrow distributed pore sizes and high N and O content,which provides abundant binding sites for acetylene（C₂H₂）and carbon dioxide（CO₂）.The optimal carbon material shows high uptake capacity for C₂H₂(2.24 mmol g^-1),and high C₂H₂/C₂H₄（10.2）and CO₂/C₂H₄（1.9）selectivity.The dynamic breakthrough experiments were conducted to evaluate the performance of carbons for the separation of ternary gas-mixture（C₂H₂/CO₂/C₂H₄）.The results indicated that the prepared carbon material can selectively adsorb C₂H₂ and CO₂ over C₂H₄,and polymer-grade C₂H₄ can be directly obtained through one breakthrough cycle.