| Summary: | Aromatic hydrocarbons along with sulfur compounds in diesel fuel pose a significant threat to catalytic performances, due mainly to carbon deposition on the catalytic surface. In order to investigate the influence of an aromatic hydrocarbon on the autothermal reforming of diesel fuel, 1-methylnaphthalene (C<sub>11</sub>H<sub>10</sub>) was selected as an aromatic hydrocarbon. Two types of diesel surrogate fuel, i.e., DH (dodecane (C<sub>12</sub>H<sub>26</sub>) and hexadecane (C<sub>16</sub>H<sub>34</sub>) mixture) as well as DHM (DH fuel and C<sub>11</sub>H<sub>10</sub> mixture) fuel, were prepared. A Rh-Al-based catalyst (R5A-I) was prepared using a conventional impregnation method. Various Ni-Al-based catalysts with Fe and Rh promoters were prepared via a polymer modified incipient method to improve the carbon coking resistance. These catalysts were tested under conditions of S/C = 1.17, O<sub>2</sub>/C = 0.24, 750 °C, and GHSV = 12,000 h<sup>-1</sup> at DH or DHM fuel. R5A-I exhibited excellent catalytic performance in both DH and DHM fuels. However, carbon coking and sulfur poisoning resistance were observed in our previous study for the Ni-Al-based catalyst with the Fe promoter, which became deactivated with increasing reaction time at the DHM fuel. In the case of the Rh promoter addition to the Ni-Al-based catalysts, the catalytic performances decreased relatively slowly with increasing (from 1 wt.% (R1N50A) to 2 wt.% (R2N50A)) content of Rh<sub>2</sub>O<sub>3</sub> at DHM fuel. The catalysts were analyzed via scanning electron microscopy combined with energy dispersive X-ray, X-ray diffraction, and X-ray photoelectron spectroscopy. Gas chromatography-mass spectrometry detected various types of hydrocarbons, e.g., ethylene (C<sub>2</sub>H<sub>4</sub>), with catalyst deactivation. The results revealed that, among the produced hydrocarbons, C<sub>2</sub>H<sub>4</sub> played a major role in accelerating carbon deposition that blocks the reforming reaction. Therefore, Rh metal deserves consideration as a carbon coking inhibitor that prevents the negative effects of the C<sub>2</sub>H<sub>4</sub> for autothermal reforming of diesel fuel in the presence of aromatic hydrocarbons.
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