Preparation Of Nano-structured Porous Carbon And Its Performance In CO₂Adsorption And Separation

The climate change such as global warming caused by greenhouse effect has been destroying the ecological environment. This makes controlling and reducing the emissions of "greenhouse" carbon dioxide (CO2) very necessary. Among all the technologies that have been developed for CO2capture, adsorption by solid adsorbents has attracted much attention over the past years. It’s believed that porous carbon is becoming one of the most promising candidates for CO2capture due to its developed porous structure, high thermal and chemical stability, excellent CO2adsorption capacity, facile regeneration ability and low cost. In this paper, porous carbon based on resorcinol-formaldehyde polymer was chosen as the adsorbent which was prepared with different synthesis conditions. The obtained carbon possesses excellent CO2adsorption ability.By taking advantage of easy decomposition and catalytic function of basic magnesium carbonate, the mechanically stable porous carbon materials (MCM-Mg) were synthesized through rapid gelation of resorcinol with formaldehyde and subsequently carbonization. The resulted samples can withstand a pressure of up to9.4MPa. With a shorter gelation time of30min, the synthesis process can also obtain a more developed porous structure. At273K, the equilibrium CO2capacities of MCM-Mg are in the range of3.49-4.50mmol-g"1at1bar and can reach1.87mmol·g-1at0.15bar. Experimental test of the MCM-Mg shows that the micropores play a major role in contribution of the amount of adsorbed CO2. Importantly, per square meter of MCM’s micropore can adsorb7.15μmol CO2which surpasses most of the carbons prepared by activation. Dynamic breakthrough tests show that, over such series of samples, CO2/N2streams can be fully separated. The CO2release can be achieved facilely in Ar purge at298K. The samples also exhibit stable performance for CO2separation under humid conditions and exhibit good regeneration capability.The porous carbon OSC was synthesized by introducing organic solvents into the reaction system. According to the "like dissolves like", the polymer can disperse better in the organic solvents and the units’size decrease at the same time which was proved by SEM. OSC exhibits a more developed porous structure which possesses a total volume as large as two times of HSC. Based on the nitrogen isotherms, it is clear that "react at90℃and then pyrolyze at800℃with a solid content of15%" is the optimal reaction condition. The sample synthesized at the optimal condition can adsorb3.11mmol·g-1CO2. The faster adsorption kinetics of OSC-D should be attributed to the smaller units (as exhibited in SEM) and the more developed porous structure (as exhibited in N2isotherms). Dynamic breakthrough tests show that, over such series of samples, CO2/N2and CO2/CH4streams can be fully separated.The porous carbon which is uniform in both macroscopic and microscopic view was synthesized by using the cheap NaCl as template, resorcinol-formaldehyde-amine as precursor, isopropanol/water as solvent. According to the N2sorption isotherm, NaCl acts as the template in the synthesis which mainly creates micropore. The template can be removed with washing by water and the sample can adsorb more CO2after the remove. More importantly, the porosity created by the template exhibits a greater ability to adsorb CO2.