Autothermal Reforming of Low-Sulfur Commercial Diesel Fuel Using Dual Catalyst Configuration of Rh/CeO₂ and Rh/Al₂O₃ for Hydrogen-Rich Syngas Production

Abstract

To utilize a well-established infrastructure of commercial diesel fuel for hydrogen production, issues related to the process parameters are essential to resolve. In this paper, catalytic autothermal reforming of low-sulfur (wt 4 ppm) commercial diesel fuel is experimentally investigated with the focus on finding the optimum operating conditions in terms of reaction temperature, O2/C, and H2O/C and comparing them with numerical analysis to obtain maximum hydrogen yield and fuel conversion. Commercial noble metal-based Rh, supported on unpromoted CeO2 and Al2O3 powders, was used as a catalyst carrier to maximize hydrogen concentration. Catalysts were used in the dual configuration of Rh/CeO2 for oxidation reaction and Rh/Al2O3 for reforming reaction in a horizontal stainless-steel tube reactor. Parameters investigated in this study were reaction temperature, gas hourly space velocity (GHSV), and catalyst stability to achieve desired results. In an effort to reduce the overall cost of the reforming system associated with catalyst carriers, the use of unpromoted Rh/CeO2 has shown significant trade-off between cost-effectiveness and stable catalytic activity due to the high Rh reducibility on the support material and strong Rh–CeO2 interaction. Experiments showed that at an elevated reaction temperature, hydrogen concentration in the reformate can be increased at the cost of a slight reduction in fuel conversion. The maximum hydrogen concentration of 28 vol % with the corresponding CO and CH4 concentrations of 3.5 and 1.5 vol %, respectively, is achieved at optimum operating conditions of reaction temperature = 850 °C, GHSV = 5000/h, O2/C = 0.9, and H2O/C = 1.9, with a fuel conversion of 97%. Out of the used catalysts, O2-temperature-programmed oxidation has shown a high degree of carbon deposition on Rh/Al2O3 as compared to Rh/CeO2 after 24 h of on-stream reaction.