CO2 Capture in Different Carbon Materials
ABSTRACT In this work, the CO(2) capture capacity of different types of carbon nanofibers (platelet, fishbone, and ribbon) and amorphous carbon have been measured at 26 °C as at different pressures. The results showed that the more graphitic carbon materials adsorbed less CO(2) than more amorphous materials. Then, the aim was to improve the CO(2) adsorption capacity of the carbon materials by increasing the porosity during the chemical activation process. After chemical activation process, the amorphous carbon and platelet CNFs increased the CO(2) adsorption capacity 1.6 times, whereas fishbone and ribbon CNFs increased their CO(2) adsorption capacity 1.1 and 8.2 times, respectively. This increase of CO(2) adsorption capacity after chemical activation was due to an increase of BET surface area and pore volume in all carbon materials. Finally, the CO(2) adsorption isotherms showed that activated amorphous carbon exhibited the best CO(2) capture capacity with 72.0 wt % of CO(2) at 26 °C and 8 bar.
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ABSTRACT: The CO2 adsorption on biochar produced by microwave pyrolysis of rice straw was investigated in this study. A microwave power level of 200 W and a maximum temperature of approximately 300 °C would be the optimal parameters to adsorb the most CO2. The CO2 adsorption capacity was up to 80 mg/g at 20 °C. The adsorption capacity decreased at higher power levels and temperatures possibly owing to the pore destruction. The CO2 adsorption capacity was highly correlated with the specific surface area of biochar. The conventional pyrolysis at 550 °C was optimal to produce the biochar absorbing the most CO2 which, however, was still lower than that of the biochar produced by microwave pyrolysis by about 14%. Low activation energy implies that CO2 adsorption on the biochar is physisorption. The ratio of CO2 quantity versus solid product quantity can almost match the CO2 adsorption capacity of the biochar produced at 200 W microwave power levels, so the microwave pyrolysis without further processes to meet the zero emission of CO2 should be workable. Compared with conventional pyrolysis, microwave pyrolysis could produce the biochar with lower time, cost, and energy consumptions.Energy 03/2015; 84. DOI:10.1016/j.energy.2015.02.026 · 4.16 Impact Factor
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ABSTRACT: Carbons with high surface area and large volume of ultramicropores were synthesized for CO2 adsorption. First, mesoporous carbons were produced by soft-templating method using triblock copolymer Pluronic F127 as a structure directing agent and formaldehyde and either phloroglucinol or resorcinol as carbon precursors. The resulting carbons were mainly mesoporous with well-developed surface area, large total pore volume, and only moderate CO2 uptake. To improve CO2 adsorption, these carbons were subjected to KOH activation to enhance their microporosity. Activated carbons showed 2-3-fold increase in the specific surface area, resulting from substantial development of microporosity (3-5-fold increase in the micropore volume). KOH activation resulted in enhanced CO2 adsorption at 760 mmHg pressure: 4.4 mrnol g(-1) at 25 degrees C, and 7 mmol g(-1) at 0 degrees C. This substantial increase in the CO2 uptake was achieved due to the development of ultramicroporosity, which was shown to be beneficial for CO2 physisorption at low pressures. The resulting materials were investigated using low-temperature nitrogen physisorption, CO2 sorption, and small-angle powder X-ray diffraction. High CO2 uptake and good cyclability (without noticeable loss in CO2 uptake after five runs) render ultramicroporous carbons as efficient CO2 adsorbents at ambient conditions.Carbon 12/2013; 65:334-340. DOI:10.1016/j.carbon.2013.08.034 · 6.16 Impact Factor
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ABSTRACT: It is emergent to reduce carbon dioxide emissions from fossil fuel combustion and thereby limit climate destabilization. In order to achieve the industrial scenario of CCS, there is a need for the discovery of better solid CO2 adsorbents that realize great improvement of selective capacity and stability to moisture as well as significant reductions in energy requirements and costs. In this review, we provide an overview of the current status of the emerging microporous metal–organic frameworks (MOFs) for the storage and separation of carbon dioxide. We summarize the main factors for CO2 capture performance of MOF materials under different working conditions, in comparison with those for zeolite materials. At the same time, we analyze the relationship among porous structures, pore/window sizes, capacity, selectivity and enthalpy of porous MOFs for CCS, which will give us clues for the design and synthesis of MOF materials as CO2 adsorbents.Energy & Environmental Science 08/2014; 7(9):2868. DOI:10.1039/C4EE00143E · 15.49 Impact Factor