New biocomposites based on castor oil polyurethane foams and ionic liquids for CO2 capture

The development of new materials with improved CO2 adsorption and selectivity capacity using raw materials from renewable sources is of great importance for sustainable development. In this work, we developed new biocomposites based on ionic liquids [BMIM][Cl], [BMIM][BF4], [EOHMIM][Gly] supported on polyurethane foam, synthesized from castor oil as polyol and HDI as isocyanate. These materials were characterized by FTIR, XPS, DSC, TGA and SEM. Tensile strength and apparent density were also determined. The pressure-decay technique was used to determine the CO2 sorption capacity in a pressure range between 4 and 30 bar, and the CO2/CH4 selectivity at 40 bar. Results indicate that the composite materials are mechanically and chemically stable with the ionic liquids within the foam pores. Foams with the higher content of IL showed high density, low blown and low pore sizes. The foam containing 15% of [BMIM][Cl] exhibited the higher capacity capture (425 mg CO2/g at 25 bar and 25 degrees C), greater than the foam without ionic liquid. It was found that at higher amounts of ionic liquid, the capture capacity decreases, and this has been related to the decrease in pore size and the increase of the density values. However, the CO2/CH4 selectivity increased proportionally with the increase of ionic liquid content. The captured gas is easily released and the foams can be reused without loss of CO2 capture capacity and just a slight loss in CO2/CH4 selectivity. (C) 2017 Elsevier B.V. All rights reserved.