Synthesis, Characterization, Adsorption and Thermodynamic Studies of Pure and Binary Co2-N2 Mixtures on Oxygen Enriched Nanostructured Carbon Adsorbents

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 m 2 g-1 , beneficial for CO 2 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 CO 2-N 2 were obtained using a fixed-bed column at different adsorption temperatures (30-100 °C) and CO 2 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 (CO 2-N 2) 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 CO 2 adsorption equilibria because of differences in adsorptive strengths of CO 2 and N 2 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 CO 2 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 CO 2 molecules on the adsorbent surface was seen as a higher heat of adsorption was exhibited for CO 2 as compared to N 2 .

Valorization of spent disposable wooden chopstick as the CO2 adsorbent for a CO2/H2 mixed gas purification

“…The breakthrough curve exhibited a huge roll-up of H 2 ( C / C 0 > 1) at the early adsorption period (< 2 min). This indicted a fast exit of H 2 in the exhaust stream or its lower adsorption compared with CO 2 67 , 68 . In other words, the as-prepared AC7-2 exhibited a strong CO 2 adsorption and a weak H 2 adsorption.…”