Hydrogen-rich gas production by steam reforming of n-dodecane: Part I: Catalytic activity of Pt/CeO2 catalysts in optimized bed configuration

Onboard diesel reformer integrated with solid oxide fuel cell (SOFC) unit offers potential for high energy conversion efficiency and low emission levels on seagoing transport, avoiding cost associated with hydrogen storage and infrastructure. However, the development of active and stable liquid hydrocarbon-reforming catalyst still remains one of the major technological barriers for fuel-cell-based auxiliary power unit (APU) applications. In this paper, the activity and stability of Pt/CeO2 catalysts were investigated towards the steam reforming (SR) of n-dodecane, used as surrogate fuel for marine diesel. Pt-based catalysts (0.6-2.3 wt.% of metal loading) were prepared by Solution Combustion Synthesis (SCS) method and characterized by XRD, N2-physisorption, CO-chemisorption, TPR, TPO and TEM techniques. Tests were performed at various process parameters, namely steam-to-carbon molar ratio (S/C = 2-3), space velocity (GHSV = 16,000-32,000 h-1) and time-on-stream. An optimized temperature-controlled (500-800 °C) bed configuration was adopted in order to avoid carbon/coke deposition due to n-dodecane cracking phenomena. Superior chemical-physical properties of 0.6 wt.% Pt/CeO2 system positively affect the SR performance. Pt-based catalyst showed catalytic activity comparable with that of the commercial Rh/ZDC (Rh/Zirconia-doped-Ceria). Total n-dodecane conversion and high H2 concentration (73%, dry and N2-free basis) were obtained at S/C = 2.5 and GHSV = 16,000 h-1. Stable catalytic activity was found under start-up and shut-down cycles for 50 h of time-on-stream. Restored catalytic performance was obtained under activity-regeneration cycles evaluated in more stressful conditions (S/C = 1.5; GHSV = 40,000 h-1). This preliminary study was finalized to a diesel fuel processor design.