(75a) PSA In Biomass to Fischer-Tropsch Fuels Processes with CO2 Capture

The use of biomass as a source of renewable energy has received much attention lately. The conversion of biomass into valuable energy can be accomplished through a variety of technologies from which gasification appears to be the most promising and efficient one. Gasification converts biomass into synthesis gas that can be further processed into a wide range of high value products such as methanol, hydrogen and Fischer-Tropsch products. However, prior to the synthesis process, the bio-syngas must be conditioned, which includes the removal of carbon dioxide for subsequent sequestration and capture. The most common technologies used for CO₂ removal from syngas are absorbent-based systems such as the Rectisol and Selexol processes. In this study a PSA process is suggested for the replacement of the absorbent-based CO₂ removal process. A pressure swing adsorption cycle was developed for the simultaneous production of a carbon dioxide enriched stream and a (H2+CO) stream with the required specifications of the Fischer-Tropsch reactor feed. An activated carbon was selected as adsorbent. Simulation results showed that it was possible to obtain a CO₂ product with purity above 95% and with 90% recovery. Additionally a H₂/CO stoichiometric ratio of 2.14 was obtained for the produced syngas stream which is adequate for further processing in the Fischer-Tropsch reactor. The power consumption of the CO₂ capture was found to be of 3.36 MW. This value represents a reduction of about 28 % when compared to a Rectisol process with the same CO₂ recovery.