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The aim of the project is the development of a new innovative and economically feasible process for the upgrading of the biogas to biomethane grade fuel through the removal of its two main pollutants, H2S and CO2. At the first stage new carbon-based adsorbents for the selective removal of hydrogen sulphide with adsorption capacity over 8.0 mmol H2S/g and diffusion coefficient higher than 10-6 cm2/s were produced.
Potassium hydroxide modified activated carbon materials (12) were prepared and wet impregnation with Ionic liquids follows (9materials). The preparation parameters of all stages (synthetic process, treatment duration, temperatures, solvents, concentrations etc) has been studied in order to find the optimum synthetic conditions. The modified and impregnated materials have been characterized using liquid nitrogen porosimetry and performing H2S adsorption isotherms measurements at various temperatures (30-70oC) and pressures (1-10 bar) in order to determine the sorption capacity and the adsorption kinetics (Diffusivity). Comparing the results obtained it became clear that potassium hydroxide modification increases the surface area of the carbon material up to 60%. Furthermore, the ionic liquid impregnation of the activated carbon materials that follows fills the pores of the material and the surface area were decreased but still the pore width is adequate to favours the H2S adsorption and the sorption capacity is higher than 8.0 mmol H2S/g sorbent. Alternative adsorbents like amino functionalized carbon materials will be prepared in order to determine the most economically feasible synthetic process along with the suitable modified activated carbon.
