(638a) Production of Jet Fuel from Coal-Derived Syngas

Authors: 
Gangwal, S., Southern Research
Venkataraman, V., U.S. Department of Energy
Southern Research under cooperative agreement with the US Department of Energy demonstrated a sulfur tolerant nickel-based reforming catalyst and a selective and active cobalt-zeolite hybrid Fischer-Tropsch (FT) catalyst to clean, upgrade and convert coal-derived syngas predominantly to jet fuel range hydrocarbon liquids, thereby minimizing expensive cleanup and wax upgrading operations. Reformer testing was performed to (1) reform tar and light hydrocarbons, (2) decompose ammonia in the presence of H2S, and (3) deliver the required H2 to CO ratio for FT synthesis. Following laboratory development and testing, a reformer system was modified to operate in a Class 1 Div. 2 industrial environment, installed at the National Carbon Capture Center (NCCC), and successfully tested for 125 hours using raw syngas. The catalyst demonstrated near equilibrium reforming (~90%) of methane and complete reforming/decomposition of tar and ammonia in the presence of up to 380 ppm H2S. Variation of steam in the feed resulted in adjustment of the H2/CO mole ratio in the syngas to a desired value between 1.8 and 2.2.

A highly efficient and selective Fischer-Tropsch (FT) process based on Chevron’s cobalt-zeolite hybrid catalyst was developed at bench-scale for producing jet fuel and diesel from syngas. The FT reactor consisted of Chevron’s hybrid jet-fuel-selective catalyst supported using Intramicron’s micro-fiber metal packing to efficiently transfer the FT reaction heat to the reactor wall. At the walls, the heat was quickly removed by a jacketed thermo-siphon system using pressurized boiling water. FT reactors ranging in internal diameters from 2 to 4 inch were tested for over 800 hours during three separate test campaigns at NCCC. The tests consistently demonstrated a FT productivity of >0.7 gram C5-C20 hydrocarbons per gram catalyst per hour, no solid wax formation, and liquid product selectivity of >70 % with little to no catalyst deactivation. The process was further optimized to achieve greater than 85 % jet fuel in the liquid product. A techno-economic evaluation based on these technologies showed that a 50,000 bpd coal to liquids plant had a 10 % lower total plant cost compared to a conventional FT slurry reactor based plant. Furthermore, because of the modular nature of the technologies, it was shown that the total plant cost advantage increased to >35 % as the plant was scaled down to 1000 bpd.

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