An attempt has been made to develop different samples of calcium silicate and to screen these samples for CO 2 sorption and alkalinity in order to achieve maximum CO 2 sorption. The CO 2 sorption capacity of these samples was examined at different temperatures. Various methods such as solid-solid fusion, sol-gel, molten salt and templates (CTAB, cetyltrimethylammonium bromide or Aliquat 336, tricaprylmethylammonium chloride) were used to prepare the calcium silicate samples. The solid mass of calcium silicate samples were obtained by calcining the solid product obtained in an atmosphere of air or helium at 900 °C for 3 hours. The calcium silicate samples were characterized for surface area, alkalinity, scanning electron microscopic images and X-ray diffraction patterns. The temperature profile of CO 2 sorption by calcium silicate was studied in the temperature range of 40-850 °C. Our results showed that the alkalinity and surface area of calcium silicate were in the range from 2.35 to 20 mmol g -1 and 1.4 to 10 m 2 g -1, respectively. The sorption of CO 2 at 500 °C over calcium silicate for the different Ca/Si mol ratio (range: 1-6) was found to be in the range from 3.12 to 29.96 wt%. Addition of a promoter such as sodium, potassium, caesium and lanthanum was found to enhance the sorption of CO 2 by calcium silicate. Several samples of different mol ratios of Ca/Si prepared by different methods were tested for the sorption of CO 2 at 500 °C.

The capture of CO 2 by transition metal (Mn, Ni, Co and Zn) aluminates, calcium aluminate, calcium zirconate, calcium silicate and lithium zirconate was carried out at pre-and post-combustion temperatures. The prepared metal adsorbents were characterized by Xray diffraction (XRD), scanning electron microscope (SEM), surface area analysis and acidity/alkalinity measurements. The different experimental variables affecting the adsorbents ability to capture CO 2 , such as the mol ratio of metal ions, the pressure of CO 2 , the exposure time and the temperature of the adsorbent were also investigated. Calcium zirconate captured 13.85 wt-% CO 2 at 650°C and 2.5 atm and calcium silicate captured 14.31 wt-% at 650°C. Molecular sieves (13X) and carbon can only capture a negligible amount of CO 2 at high temperatures (300°C-650°C). However, the mixed metal oxides captured reasonable amount of CO 2 at these higher temperatures. In addition, calcium aluminate, calcium zirconate, calcium silicate and lithium zirconate adsorbents captured CO 2 at both pre and post-combustion temperatures. The trend for the amount of captured carbon dioxide over the adsorbents was calcium aluminate < lithium zirconate < calcium zirconate < calcium silicate.

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The uses of copper and zinc aluminates to capture and convert the CO2 to syn-gas were studied at higher temperatures. The samples of copper and zinc aluminates were prepared by solid-solid fusion method by calcining in air at 900 o C for 3 h. Those samples were characterized by acidity/alkalinity, surface area, XRD pattern, IR, SEM images and screening to capture CO2 at the different temperatures. The phases Cu2O, CuO, ZnO, CuAl2O4 and ZnAl2O4 were found to be in the samples of zinc and copper aluminates. Acidity and surface area of the samples of copper and zinc aluminates were found to be in the ranges from 0.063 to 9.37 mmol g -1 and 3.04 to 11.8 m 2 g -1 , respectively. The captured CO2 by the samples of copper and zinc aluminates was found to be 19.92 to 31.52 wt% for the temperature range 40 to 850 o C. The captured CO2 at 550 o C by variable Zn/Al and Cu/Al mole ratio from 0.5 to 6 of the samples of copper and zinc aluminates was found to be 12.81 to 18.04 wt%. The reduction of carbon dioxide by zinc and copper aluminates was observed. The conversion of CO2 by methane over variable mole ratio of Cu/Al and Zn/Al in copper and zinc aluminates, respectively, at 500 o C showed the production of syn-gas by using the gas hourly space velocities (GHSV) 12000, 12000 and 6000 ml.h -1 .g -1 of helium, CO2 and methane. The conversions of CO2 by methane over the samples of zinc and copper aluminates were studied at different mole ratios of CO2 to methane.

The applications of different mixed metal oxides were explored for the capture of CO2 and convert of CO2 to syn-gas. The several samples of the mixed metal oxides were prepared by the sol-gel, solid-solid fusion, precipitation, molten salt and template methods in order to investigate the performance of mixed metal oxides to the CO2 applications. These samples were calcined for the 3 h in air at 900 o C. The mixed metal oxides samples were characterized by acidity/basicity, surface area, XRD pattern, SEM images and to capture CO2. The basicity and surface area of the samples of mixed metal oxides were found to be in the range from 0.7 to 15.7 mmol.g -1 and 2.24 to 138.76 m 2 .g -1 , respectively. The obtained results of prepared mixed metal oxides by different method were compared for the purpose of searching the efficient materials. The temperature profiles of the captured CO2 by the samples of mixed metal oxides were obtained in the range 100 to 800 o C. The captured CO2 was found to be in the range from 7.36 to 26.93 wt.%. The conversions of CO2 by methane were explored to syn-gas over the mixed metal oxides including the calcium iron lanthanum mixed metal oxides and (5 wt.%) Pd/Al2O3 at 700 o C with the gas hourly space velocities (GHSV) 6000 ml.h -1 .g -1 of methane, 6000 ml.h -1 .g -1 of CO2 and 24000 ml.h -1 .g -1 of helium.