High Throughput Screening of Catalytic Materials for JP-8 Fuel Reformation

Within the past decade, the high-throughput approach has become widespread in the field of catalysis (1-3).  In this work, this methodology is applied for the discovery and optimization of catalytic materials for reformation of military jet fuel (JP-8) to lighter hydrocarbons.  JP-8 is the single battlefield fuel of NATO and the U.S. Military.  These organizations have a critical need for converting their preferred fuel source into a flexible and readily available power supply for portable applications, such as solid oxide fuel cells and liquefied petroleum gas.  The objective of this work is to use a high-throughput screening approach to discover and optimize novel reforming catalyst formulations that will enable reforming technology to convert readily available hydrocarbon-based fuels, such as JP-8, directly to a lighter hydrocarbon feed suitable for portable fuel cell applications.

An existing high-throughput reactor system (4) was modified for the JP-8 reforming studies.  The reactor system consists of 16 separate stainless steel reactor tubes that are loaded with individual powder catalyst samples, typically between 150 mg and 750 mg, and tested under realistic conditions.  The high-throughput reactor system operates at ambient pressure with a temperature range between room temperature and 1100 K and space velocities between 3,500 (mL/hr * g_cat) and 200,000 (mL/hr * g_cat).  Liquid JP-8 is dosed into a heated mixer with high internal evaporative surface area, where it is vaporized and combined with carrier gas to form the reactant gas feed.  The reactor effluent streams from each of the individual reactors remain in separate channels throughout the analysis process to prevent the mixing of reaction products from occurring.  The reactor effluent passes through a parallel condenser system to remove any unreacted JP-8 before proceeding for analysis.

The gaseous product stream then enters a rapid-scan Fourier transform infrared (FTIR) spectroscopic imaging system.  This system enables chemically-sensitive, parallel screening of all 16 gas-phase reactor product distributions through a gas phase array (GPA), incorporating a 128x128 focal plane array (FPA) detector as the infrared (IR) detecting element.  In addition, a gas chromatography-mass spectrometry (GC-MS) system is incorporated via a computer controlled 16-way switching valve and allows for further quantitative analysis of the product composition of the effluent streams.  The GC-MS is capable of identifying and differentiating between specific hydrocarbon molecules and was calibrated to provide compositional information for each desired product.

Catalysts are analyzed for their desired properties, such as conversion, selectivity, sulfur tolerance, and coking resistance.  Because JP-8 may contain up to 3,000 ppmw sulfur, sulfur-tolerant reforming catalysts that can withstand coking and demonstrate long-term activity and stability are required.  Catalysts that can produce a well-defined sulfur-containing product distribution can be optimized using existing clean coal technology for removal of sulfur compounds.  By applying a high throughput methodology to this process, a large number of materials are screened, including several monometallic transition metals, such as Rh, Pd, Pt, Ru, and Ir, as well as bimetallic combinations involving active metals.  In addition, several oxide support materials, including Al₂O₃, SiO₂, CeO₂, ZrO₂, MoO₂, and Nb₂O₅, were synthesized and tested.  The high throughput methodology allows for a comprehensive search of the parameter space affecting catalyst performance, including catalyst composition, support materials, operating conditions, as well as pre-treatment options.

1.            R. J. Hendershot, C. M. Snively, J. Lauterbach, High-throughput catalytic science. Chemistry-A European Journal 11, 806 (Jan 21, 2005).

2.            W. F. Maier, K. Stowe, S. Sieg, Combinatorial and high-throughput materials science. Angewandte Chemie-International Edition 46, 6016 (2007).

3.            I. Takeuchi, J. Lauterbach, M. Fasolka, in Materials Today. (2005), vol. 8, pp. 18-26.

4.            R. J. Hendershot et al., A novel reactor system for high throughput catalyst testing under realistic conditions. Applied Catalysis a-General 254, 107 (Nov 10, 2003).