Breakthrough adsorption study of a commercial activated carbon for pre-combustion CO2 capture

Abstract

In this study a commercial activated carbon (Norit R2030CO2) was assessed as a solid sorbent for precombustion CO2 capture. This technology involves the removal of CO2 from the shifted-syngas prior to the generation of electricity and the production of high-purity clean H2. The CO2 equilibrium adsorption capacity and breakthrough time were evaluated in a flow-through system where the adsorbent was subjected to four consecutive adsorption–desorption cycles. A CO2/H2/N2 gas mixture (20/70/10vol.% at normal conditions) was employed as the influent gas stream. Response surface methodology (RSM) was used to assess the combined effect of the adsorption CO2 partial pressure and temperature (independent variables) on CO2 capture capacity and breakthrough time (response variables) for the activated carbon. The CO2 partial pressure ranged from 1 to 3bar within a total pressure range of 5–15bar and a temperature range of 25–65°C. No interaction effect between the two independent variables on the responses was found. The CO2 partial pressure was observed to be the most influential variable, with high values leading to an increase in both the CO2 capture capacity and the breakthrough time. However, an increase in the temperature led to a decrease in both response variables. The maximum values of the response variables within the experimental region studied were obtained at 25°C and under a CO2 partial pressure of 3bar (15bar total pressure).