Discovery and Optimization of Coking and Sulfur Resistant Bi- Metallic Catalyst for Cracking JP-8: From Thin Film Libraries to Single Powders

The recent development of solid oxide fuel cells (SOFC) capable of using liquefied petroleum gas (LPG) as a feedstock has created a viable high energy density technology for replacing the diesel generators and batteries used to create power in remote or mobile applications. Due to the unsurpassed volumetric energy density of liquid hydrocarbon fuels and the existing infrastructure for their distribution, it is preferable to transport and store diesel and jet fuel and catalytically crack it on-site to LPG. The ideal cracking catalyst must be capable of operating without excessively coking or being poisoned by sulfur present in the feedstock, and must be capable of being regenerated at temperatures similar to the reaction temperature, preferably using only air. These stringent requirements required rapidly identifying a series of base catalysts with high activity towards cracking, an additional series of potential additives to mitigate coking and promote regeneration, and the final verification of their combined properties to ensure optimal performance. Here we demonstrate a comprehensive and iterative high-throughput (HT) methodology for identifying such novel catalyst formulations with high activity towards cracking to LPG, which are capable of being operated for extended periods of time and regenerated in air multiple times without degradation in their activity. The approach combines a rapid, qualitative primary optical screen via thin-film techniques, a series of quantitative screens using mg powder quantities, and a final verification of the best samples using a single sample reactor. This versatile approach permitted the systematic study of a large phase-space of potential catalysts and additives combinations, ranging from noble metal promoted simple oxide catalysts to zeolite based catalysts. Initial studies focused on the identification of a catalyst with suitable activity, in excess of 20% conversion, using a 16-well reactor. This portion of the work focused on providing a comprehensive quantification of the product distribution of the different catalysts using industrially available catalyst formulations. Subsequently, thin-film samples with a spread of compositions deposited as nanoparticles on the surface of the most active catalysts were employed to screen bi-metallic additives for their relative coking and regeneration rates. Several additives with the highest figure of merit were recommended for a second round of screening of bi-metallic promoted zeolites in the 16-well reactor, where the emphasis shifted to evaluating the effect of both the additives and multiple regenerations on the product distribution. Final verification of the best additivemodified catalyst was obtained in a single reactor in which the catalyst was run under a highly concentrated feed for multiple days and demonstrated negligible degradation.

Keywords: High-throughput screening, catalysis, zeolite, oxide, impregnated, ion-exchanged, ZSM-5, Pt, Gd, JP-8, LPG, catalytic cracking, thin film, regeneration, fuel cracker.