Studies On Adsorption Of CO₂on Polyporous Silicate Material

The emission of CO2into atmosphere due to combustion of fossil fuels hasemerged as an important environmental problem. The key of this problem can beachieved by increasing energy efficiency, and use of renewable sources for energyproduction. One suggested way of securing energy supply and environmentalprotection can be achieved by CO2capture and storage (CCS). There are severaltechniques which can be employed to remove CO2from industrial streams: absorption,membranes, cryogenic separations, and adsorption. Capture of CO2by adsorptionmethod from flue gases of power plants was considered frequently in recent works.This method can present operating flexibility, energy efficiency and low capitalinvestment. In this work, polyporous silicate material was employed as the selectiveadsorbent to investigate the CO2capture from flue gas. The main contents includefour parts as follows:(1) To know the chemical characteristics of polyporous silicate material. In thiswork, the polyporous silicate material was characterized using XRD, SEM, FTIRspectroscopy, TGA-DSC, and elemental analysis. These spectral results show that thesilicate material is mainly composed of seven elements including O, C, Si, Ca, Na,Mg, and Al, which exist as the formations of Ca2+, Na+, Mg2+, Al3+, SiO2--3, and CO23,and some adsorbed water and crystal water are determined in the silicate material. Thematerial with surface area of117.12m2/g has a faveolate structure, and a mesoporouspore size distribution to provide adsorptive sites.(2) Adsorption capacity of CO2/N2gases on polyporous silicate material. Whenthe material was used to impart interaction sites for CO2adsorption, a dynamicadsorption capacity of the polyporous silicate material for CO2of8.67mg/g at t=50℃and flow rate=95mL/min was found based on dynamic adsorption method andthe adsorption ability decreases weakly with seventeen recycling times. Theadsorption capacity of silicate material increases with the decreasing adsorptivetemperature and total gas flow rate.(3) The investigation of dynamic adsorption behavior shows that the polyporoussilicate material presents similar adsorption properties with commercial active carbonand stronger adsorption properties than commercial diatomite. (4) The adsorption mechanism of CO2on polyporous silicate materials werecharacterized by XRD, SEM, FTIR spectroscopies, specific surface&pore sizeanalysis and elemental analysis. It is observed that the physical effect is uppermost inthe experiments.The adsorptive ability of CO2on polyporous silicate material is huge. Therefore,the polyporous silicate material will be a particularly efficient and competitiveadsorbent for CO2recovery after modified technology and material.