JP-8 catalytic cracking for compact fuel processors

Abstract

In processing heavier hydrocarbons such as military logistic fuels (JP-4, JP-5, JP-8, and JP-100), kerosene, gasoline, and diesel to produce hydrogen for fuel cell use, several issues arise. First, these fuels have high sulfur content, which can poison and deactivate components of the reforming process and the fuel cell stack; second, these fuels may contain non-volatile residue (NVR), up to 1.5 vol.%, which could potentially accumulate in a fuel processor; and third is the high coking potential of heavy hydrocarbons. Catalytic cracking of a distillate fuel prior to reforming can resolve these issues. Cracking using an appropriate catalyst can convert the various heavy organosulfur species in the fuel to lighter sulfur species such as hydrogen sulfide (H2S), facilitating subsequent sulfur adsorption on zinc oxide (ZnO). Cracking followed by separation of light cracked gas from heavies effectively eliminates non-volatile aromatic species. Catalytic cracking can also convert heavier hydrocarbons to lights (C1–C3) at high conversion, which reduces the potential for coke formation in the reforming process. In this study, two types of catalysts were compared for JP-8 cracking performance: commercially-available zeolite materials similar to catalysts formulated for fluidized catalytic cracking (FCC) processes, and a novel manganese/alumina catalyst, which was previously reported to provide high selectivity to lights and low coke yield. Experiments were designed to test each catalyst’s effectiveness under the high space velocity conditions necessary for use in compact, lightweight fuel processor systems. Cracking conversion results, as well as sulfur and hydrocarbon distributions in the light cracked gas, are presented for the two catalysts to provide a performance comparison.