Chemical Synthesis Of Nano-porous Carbon And Its Application In CO₂Adsorption And Separation

The greenhouse effect is one of the common challenges faced by the whole world. Thus the carbon dioxide (CO2) emission is a focus attention of the governments. Among the various CO2capture technologies and processes that have been developed, the physical adsorption method has gradually become an every important one like a star due to its low power consumption, depth removal, no corrosion and ease operation. Design and preparation of adsorption materials is one of the key points of such CO2capture technology. Duo to its developed porousity, strong hydrophobicity, high thermal and chemical stability, low renewable energy consumption and low cost, porous carbon is considered to be one of the most promising candidates for CO2capture. Polymer-based porous carbon synthesized via chemical method is pure and controlable. More importantly, the modulation of both macroscopic and microscopic scales of the porous carbon can be achieved through the "bottom-up" molecular design and synthesis process. The present thesis focuses on the chemical synthesis of porous carbon, and concentrates on working on studying the relationship between the structure and surface property of carbon sorbent and CO2adsorption and separation performance. Specific information is as follows:(1) Aiming to settle the issues of low CO2capacity and selectivity by modified approach, hereachtically nitrogen-rich porous carbon containing micropores, mesopores and macropores was synthesized by nanocasting method using novel nitrogen-containing polymer (Schiff base) as precursor and mesoporous SBA-15as hard template. Nitrogen content of sample is up to7.85wt%. Due to the synergy effect of pore structure and surface property, the CO2capacity is4.33mmol g-1at ambient pressure and273K, separation ratios of CO2/N2and CO2/CH4are7.0and3.2, respectively; Henry’s low selectivity are23.3and4.2, respectively; The predicted IAST adsorption selectivity of two-component mixed stream are40and18, respectively.(2) In order to improve the kinetics of CO2adsorption-desorption and surface area utilization of microporous carbon, two-dimentional sandwiched-type microporous carbon nanosheets were synthesized by ionic liquids assisted synthesis process based on a spirit for reducing the size of building units to nanometer scale in the dimension of the XOY plane of graphene. The thickness of coating carbon layer is precisely adjustable in the range of10-100nm, graphene content of the samples ranges between0.26%-2.72%and the micropore size is ca.0.54nm. Both model calculation and gas adsorption test show that a representative sample demonstrates faster adsorption-desorption kinetics, higher utilization rate of microporosity.(3) Taking into account of strong impact force, large flow and water vapor containing features of CO2gas source, as well as the deficiency of chalking and pore plugging when molding porous carbon powders in practical applications, intact monolithic mesoporous carbon with controlled structure and excellent mechanical properties was prepared via one-step and fast so-gel method. The mechanical strength is up to7.8MPa, and40times higher than similar carbon materials; the mesopore is ca.5nm, the specific surface areas and pore volum range between774-2578m2g-1and0.46-1.31cm3g-1, respectively. A10-fold magnification synthesis has no effect on pore structure. The sample shows high CO2capacity, good selectivity, good regeneration and cycle stability and excellent resistance to moisture.