Green coffee based CO2 adsorbent with high performance in postcombustion conditions

An environmentally friendly and low cost adsorbent, PPC (patent application filed Gonzalez (2013)), produced from an abundant residue from the food industry, coffee grounds, is presented and evaluated as CO2 adsorbent in postcombustion conditions. PPC is a high bulk density pelletized carbon with adequate properties for its use in fixed-bed adsorption applications. The equilibrium capacity for CO2 at low partial pressures, relevant for the postcombustion case, in the 25-50 degrees C temperature range is superior to that of reference carbons, both in mass and volume basis. PPC presents equilibrium selectivity for CO2 over N-2, with CO2/N-2 equilibrium separation factor values of 15-25 at 50 degrees C and 130 kPa for CO2 concentrations between 9% and 31%. Moreover, it presents fast adsorption kinetics, which makes it a good candidate for rapid swing adsorption cycles. Different VSA cycle configurations were carried out at 50 degrees C in the fixed-bed adsorption unit to evaluate the performance of the adsorbent in cyclic operation. The adsorbent did not show any sign of deactivation over extended operation. (C) 2014 Elsevier Ltd. All rights reserved.