Thermochemical conversion of lignocellulosic biomass - olive pomace - into activated biocarbon for CO2 adsorption

This study aims to produce three kinds of activated biocarbon prepared from lignocellulosic biomass - olive pomace – by thermochemical treatment by steam, K2CO3, and simultaneous steam and K2CO3 at the temperature of 600 °C. The characterization of the activated biocarbon samples was carried out via several instrumental techniques such as TGA, XRD, FTIR, Raman, and N2 sorption at the temperature of 77 K. The values of the specific surface area, of the prepared activated carbons, determined by means of N2 adsorption measurements were between 5 and 600 m2/g. The CO2 adsorption equal to 2.63 mmol/g at the pressure of 1 bar and the temperature of 0 °C was achieved. The activated biocarbons produced from olive pomace by combined physical and chemical activation showed considerable promise for flue gas carbon capture applications. The values of adsorption at 0.15 bar were more than 50 % of adsorption at 1 bar pressure for all investigated activated carbons. High selectivity of CO2 over N2 equal to 29 was achieved for the gas composition of 15 % v/v CO2 and 75 % v/v N2. For CO2 adsorption the small pore volume (diameter ≤0.79 nm for 1 bar and diameter ≤ 0.55 nm for 0.15 bar) at the temperature of 0 °C was crucial and the chemistry of the surface is not very important.