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.
The CO2 adsorption by calcium zirconate was explored at pre- and post- combustion temperature condition. The several samples of the calcium zirconate were prepared by different methods such as sol-gel, solid-solid fusion, template and micro-emulsion. The samples of the calcium zirconate were characterized by measurement of surface area, alkalinity/acidity, and recording the XRD patterns and SEM images. The CO2 adsorptions by samples of the calcium zirconate were studied in the temperature range 100 to 850 oC and the CO2 adsorptions were observed in the ranges of 6.88 to 40.6 wt % at 600 0C and 8 to 16.82 wt% at in between the temperatures 200 to 300 oC. The effect of Ca/Zr mol ratio in the samples of the calcium zirconate on the CO2 adsorption and alkalinity were discussed. The adsorbed moisture by the samples of the calcium zirconate was found to be useful for the CO2 adsorption. The promoted the samples of the calcium zirconate by K+, Na+, Rb+, Cs+, Ag+ and La3+ showed the increased CO2 adsorption. The exposure time of CO2 on the samples of the calcium zirconate showed the increased CO2 adsorption. The samples of the calcium zirconate were found to be regenerable and reusable several times for the adsorption of CO2 for at the post- and pre-combustion temperature condition. Copyright © 2012 by BCREC Undip. All rights reserved Received: 23rd June 2012, Revised: 28th August 2012, Accepted: 30th August 2012 [How to Cite: K. B. Kale, R. Y. Raskar, V. H. Rane and A. G. Gaikwad (2012). Carbon Dioxide Adsorption by Calcium Zirconate at Higher Temperature. Bulletin of Chemical Reaction Engineering & Catalysis, 7 (2): 124-136. doi:10.9767/bcrec.7.2.3686.124-136] [How to Link / DOI: http://dx.doi.org/10.9767/bcrec.7.2.3686.124-136 ]
The de-oxygenation of CO2 was explored by using hydrogen, methane, carbon etc., over alumina supported catalysts. The alumina-supported ruthenium, rhodium, platinum, molybdenum, vanadium and magnesium catalysts were first reduced in hydrogen atmosphere and then used for the de-oxygenation of CO2. Furthermore, experimental variables for the de-oxygenation of CO2 were temperature (range 50 to 650 oC), H2/CO2 mole ratios (1.0 to 5), and catalyst loading (0.5 to 10 wt %). During the de-oxygenation of CO2 with H2 or CH4 or carbon, conversion of CO2, selectivity to CO and CH4 were estimated. Moreover, 25.4 % conversion of CO2 by hydrogen was observed over 1 wt% Pt/Al2O3 catalyst at 650 oC with 33.8 % selectivity to CH4. However, 8.1 to 13.9 % conversion of CO2 was observed over 1 wt% Pt/Al2O3 catalyst at 550 oC in the presence of both H2 and CH4. Moreover, 42.8 to 79.4 % CH4 was converted with 9 to 23.1 % selectivity to CO. It was observed that the de-oxygenation of CO2 by hydrogen, carbon and methane produced carbon, CO and CH4. © 2012 BCREC UNDIP. All rights reserved Received: 6th February 2012; Revised: 23rd April 2012; Accepted: 24th April 2012 [How to Cite: R. Y. Raskar, K. B. Kale, A. G. Gaikwad. (2011). De-oxygenation of CO2 by using Hydrogen, Carbon and Methane over Alumina-Supported Catalysts. Bulletin of Chemical Reaction Engineering & Catalysis, 7 (1): 59-69. doi:10.9767/bcrec.7.1.1631.59-69] [How to Link / DOI: http://dx.doi.org/10.9767/bcrec.7.1.1631.59-69 ] | View in
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