Abstract
Abstract Oxygen enriched porous carbons have been synthesized by a nanocasting technique using mesoporous zeolite as template and epoxy resin as precursor. Characterization results show the effect of the nanocasting technique on the development of heterogeneous surface, high basicity, and high surface area of 686.37 m2g-1, beneficial for CO2 adsorption. Pure component adsorption isotherms were correlated with Langmuir, Sips, and dual-site Langmuir (DSL) models and found that Sips and DSL isotherm models fitted well, indicating thre heterogeneous nature of the adsorbent surface. Dynamic breakthrough data for the binary system CO2-N2 were obtained using a fixed-bed column at different adsorption temperatures (30-100 °C) and CO2 feed concentrations (5-12.5% by volume). The developed adsorbent shows high adsorption capacity with complete regenerability over four adsorption/desorption cycles. Prediction of binary components (CO2-N2) was made by using extended Sips, extended DSL and IAST (ideal adsorbed solution theory) by utilizing pure component adsorption isotherm data. Experimental and predicted equilibrium data were compared with breakthrough curve data and it was found that the extended forms (Sips and DSL) indicated under-predicted CO2 adsorption equilibria because of differences in adsorptive strengths of CO2 and N2 molecules. Also, adsorption equilibria were closely predicted using IAST theory. Asymmetric x-y diagrams from Raoult’s law indicated positive deviation, implying that as the CO2 gas phase molar fraction increases, total adsorbed amounts increase. Negative values of molar Gibbs free energy change suggested feasibility of the adsorption process. Formation of a more ordered configuration of CO2 molecules on the adsorbent surface was seen as a higher heat of adsorption was exhibited for CO2 as compared to N2.
Highlights
Nowadays, the world is facing tremendous challenges due to the increase in greenhouse gas emissions, which causes a major global warming problem
Among the preparation techniques, nanocasting developed the materials having controlled pore structure used in this study
Carbon adsorbents obtained from high oxygen containing epoxy resin and using as template mesoporous MCM-41 can act as a potential adsorbent for selectively capturing CO2
Summary
The world is facing tremendous challenges due to the increase in greenhouse gas emissions (mainly carbon dioxide), which causes a major global warming problem. Zeolites (Deng et al, 2012), activated carbons (Wang et al, 2012; Yoo et al, 2013), metal-organic frameworks (Bastin et al, 2008; Sumida et al, 2012), amine supported mesoporous materials (Melloa et al, 2011; Xu et al, 2009) are potential candidates used so far, but among these, carbon based adsorbents have been studied extensively due to their better properties like well-developed porous structures, high adsorption capacities, easy regenerability, fast kinetics coupled with high thermal and chemical stability. It is possible to improve the textural properties, it is less time-consuming and it is possible to control pore structure characteristics In this technique, precursor is introduced into the template pores, carbonized and lastly the template is removed. Carbon adsorbents obtained from high oxygen containing epoxy resin and using as template mesoporous MCM-41 can act as a potential adsorbent for selectively capturing CO2
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