Study of sulfur-resistant Ni-Al-based catalysts for autothermal reforming of dodecane

摘要

Diesel fuel has merits such as good refueling infrastructure and high hydrogen density, but it also contains small amounts of sulfur compounds that deactivate reforming catalysts by sulfur poisoning. In this work, various promoters such as La (NAL10-PM), Ce (NAC10-PM), and Fe (NAF10-PM) were used to improve the catalytic activities of Ni-Al-based reforming catalysts in the presence of sulfur compounds. Various Ni-Al-based catalysts were prepared by a polymer-modified incipient method using polymethyl methacrylate (PMMA). The tests were performed in a fixed-bed reactor, and dodecane and dibenzothiophene (DBT) were used as the surrogate diesel fuel and sulfur compound, respectively. In the presence of 100 ppm DBT, the NAF10-PM catalyst maintained 80% dodecane conversion without deactivation for 6 h, although the other catalysts were deactivated; the conditions were S/C = 1.23, O-2/C = 0.25, 750 degrees C, and a gas hourly space velocity of 12,000 h(-1). Scanning electron microscopy-energy-dispersive X-ray spectroscopy and X-ray photoelectron spectroscopy showed that catalyst deactivation was caused by the deposition of large amounts of graphitic carbon on the catalyst surface in the presence of 100 ppm DBT. Lesser graphitic carbon was deposited on the NAF10-PM catalyst than the other catalysts, and catalytic activity was maintained even in the presence of DBT. In addition, X-ray diffraction showed the formation of a Ni-Fe alloy in the NAF10-PM catalyst. It is suggested that the Ni-Fe alloy prevented the deposition of graphitic carbon, and thus catalyst deactivation. In summary, the catalytic activity for autothermal reforming of dodecane on the Fe-promoted NAF10-PM catalyst was excellent, and no deactivation occurred in the presence of 100 ppm DBT. Copyright (C) 2015, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.