Optimization of adsorptive desulfurization process of jet fuels for application in fuel cell systems

In order to remove the sulfur compounds in jet fuels to produce ultra-clean fuels e.g., for fuel cell applications in aircraft (auxiliary power units, APUs), an integrated desulfurization process was developed, which combines a fixed-bed adsorption with a membrane separation. The present study focuses on the optimizing the fixed-bed adsorption with an Al2O3-based adsorbent. A sulfur level of 10 ppmw is required by the fuel cell system. 1 g of the adsorbent is capable of processing 7.43 ml of a 50% (vol.) light fraction of Jet A-1 with 440 ppmw under optimum operating conditions. The maximum sulfur adsorption capacity is approximately 2.51 mg S/g of adsorbent. The sulfur-loaded adsorbent can be regenerated by air rather than by hydrogen-containing gasses at an elevated temperature of 500 °C. However, the regenerated adsorbent only maintains a stable cyclic capacity of 2.01 mg S/g-ads over 70 adsorption–desorption cycles. In addition, the adsorbent bed dimensions with regard to bed length, bed diameter and particle size were optimized to obtain the desired sulfur adsorption capacity without encountering a significant pressure drop across the adsorption column.