Hydrodesulfurization process with pre-saturation using reformate for application in a 5 kW fuel cell system

Fuel-cell-powered APUs (auxiliary power units) are advantageous for on-board electricity supply in heavy trucks, airplanes and ships due to their high efficiency and operation with low emissions. To operate the fuel cells with the fuel available on-board, a desulfurization process is required to avoid the catalyst deactivation in the fuel reforming unit and the fuel cells. The present study aims at developing a modified hydrodesulfurization (HDS) process. The principle underlying this process is the pre-saturation of sulfur-containing fuels with hydrogen-rich reformate. In a pre-saturator, the reformate is mixed with the liquid fuel and compressed to the saturation pressure. This paper presents experimental results demonstrating the desulfurization performance for treating a commercial jet fuel and a high sulfur diesel fuel. A commercial jet fuel with up to 813 ppmw S was desulfurized by a H2-containing reformate to a sulfur level under 10 ppmw at an operating temperature in the range of 360 °C to 390 °C and a pressure of 30 bar to 70 bar. Under these conditions a high sulfur diesel fuel was desulfurized to the desired sulfur level as well. A long-term experiment running for up to 602 h verified the durability of the investigated HDS process.