Preparation, Modification And CO₂Adsorption Properties Of Layered Double Hydroxides

Since the industrial revolution, carbon dioxide and other greenhouse gases emission increased rapidly caused by the combustion of many fossil fuels.The releases large volumes of carbon dioxide to the environment become one of the most serious global environmental problems. The removal and recovery of carbon dioxide has drawn wide attention of many countries and scientists. The carbon dioxide from power plant fuel gases is considered to be one of the effective approaches for reducing total carbon dioxide emission. Solid adsorption material, which have various advantages, such as low energy consumption, low corrosion, wide application temperature, no secondary pollution, has a wide application prospect.Three kinds of layered double hydroxides intercalated by anionic surfactants were prepared by co-precipitation method and the anionic surfactants included sodium dodecyl sulfate, sodium laurylsulfonate, and sodium dodecyl benzenesulfonate. Amine modified NiMgAl layered double hydroxides have been synthesized via an exfoliation and grafting method. The samples were characterized by elemental analysis, X-ray diffraction (XRD), diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), and thermogravimetric analysis (TGA). Adsorption of carbon dioxide on modified layered double hydroxides was investigated by TGA at25-150℃. Layered double hydroxide intercalated by sodium dodecyl sulfate has the biggest specific surface area and best regeneration performance. Its’ CO2adsorption capacity was0.78mmol/g at30℃and0.14mmol/g at80℃. NiMgAl N2showed a maximum CO2adsorption capacity of2.02mmol g-1in pure CO2and1.89mmol g-1in15%CO2/N2at80℃. The optimum desorption temperature is140℃for NiMgAl N2according to adsorption/desorption experiments. By in-situ DRIFTS, the adsorption of CO2on NiMgAl N2followed the mechanism of formation of ammonium carbamate ion pairs.The research will provide theoretical basis for the design of functional adsorption material and a potential technology process for CO2capture.