CO2 adsorption on fine activated carbon in a sound assisted fluidized bed: Effect of sound intensity and frequency, CO2 partial pressure and fluidization velocity

Abstract

Among all the CCS strategies, post-combustion capture provides a near-term solution for stationary fossil fuel-fired power plants, eliminating the need for substantial modifications to existing combustion processes and facilities. In this respect, adsorption using solid sorbents has the potential, in terms of energy saving, to complement or replace the current absorption technology. Therefore, the design of highly specific CO2 adsorbents materials is requested. In this framework, great interest is focused on nanomaterials, whose chemico-physical properties can be tuned at the molecular level. As regards the handling of such materials, sound-assisted fluidization is one of the best technological options to improve the gas–solid contact by promoting a smooth fluidization regime. The present work is focused on the CO2 capture by sound-assisted fluidized bed of fine activated carbon. Tests have been performed in a laboratory scale experimental set-up at ambient temperature and pressure, pointing out the effect of CO2 partial pressure, superficial gas velocity, sound intensity and frequency. Effectiveness of CO2 adsorption has been assessed in terms of the moles of CO2 adsorbed per unit mass of adsorbent, the breakthrough time and the fraction of bed utilized at breakpoint. The results show, on one hand, the capability of the sound in enhancing the adsorption process and, on the other hand, confirm that sound assisted fluidization of fine solid sorbents is a valid alternative to the fixed bed technology, which require also an additional previous step of pelletization.