A goal of the United States Department of Energy (DOE) is to develop a diesel-based transportation system for trucks, including vans and multipurpose vehicles, that can accommodate a variety of diesel fuels and that would achieve extremely low emissions and high fuel efficiency. A key element in this strategy is to produce, via Fischer-Tropsch (F-T) and other synthesis-gas conversion technologies, premium transportation fuels from non-petroleum feedstocks, such as coal, natural gas and biomass.
J. Winslow, of the Federal Energy Technology Center (FETC), et al. discussed the development of these technologies at the 1999 International Pittsburgh Coal Conference held in Pittsburgh, Pennsylvania, in October 1999.
Because of the potential benefits of F-T and similar technologies, the DOE’s FETC has been active for many years in the promotion of synthesis gas conversion processes.
There are a number of aspects to DOE’s fuels-development program, including the development of F-T catalysts; development of processes for converting synthesis gas to chemical intermediates and fuels, such as methanol and dimethyl ether; proof-of-concept demonstrations of these processes; and development of engineering data and mathematical models to permit the design of Slurry Bubble Column Reactors (SBCR). The current synthesis gas conversion activities focus on developing novel slurry-phase reactor technologies, which exhibit greater flexibility and are technically and economically superior to existing, fixed-bed reactor systems, and on laboratory and bench-scale research on catalysts for producing a suite of hydrocarbons and oxygenates, which can be used to produce ultraclean diesel, gasoline and jet fuels for the vehicles of the future.
The success of DOE’s Synthesis Gas Conversion activities centers around the DOE-owned Alternative Fuels Development Unit in LaPorte, Texas, operated by Air Products and Chemicals, Inc. This facility is capable of processing synthesis gas, with a wide range of compositions in an SBCR—the heart of liquid-phase technology—to demonstrate operation at an industrially relevant scale of 5 to 15 tons per day. The Liquid Phase Methanol (LPMEOH) process, successfully developed through use of the LaPorte facility, is now being commercially demonstrated at the Eastman Chemical Company’s Chemicals-from-Coal complex, located in Kingsport, Tennessee, with support from DOE’s Clean Coal Technology Program. In addition, the F-T process, has been given new life by the use of SBCR technology. The success achieved in these programs has shown the strong potential of SBCR technology to improve the economics of processes to convert coal- or natural gas-derived synthesis gas to an optimum distribution of fuels and chemicals.Implementation Strategy
Although commercial plants utilizing both fixed-bed and fluidized-bed reactors have operated, there have been no large-scale F-T plants using slurry reactors. (Sasol does have a demonstration-size slurry reactor operating at one of their facilities.) Much useful data would be generated by an operating a slurry-reactor-based F-T plant. In addition to proving out equipment and operating procedures, an operating plant would provide large quantities of F-T product to allow refiners to find the optimum way to integrate F-T liquids into their refineries. In addition, a commercially successful plant would provide confidence to others to build plants.
The potential for the successful implementation of slurry-reactor F-T technology in the near term is high. The new slurry-phase process removes the economic barrier and makes synthesis gas conversion into liquid fuels a real and commercially attractive option now. Remote natural gas reserves present a niche opportunity for demonstrating slurry-reactor technology, which would be followed by coal-based plants. A strong research, development and demonstration program is in place to ensure continued development and cost reduction. The work accomplished by these projects will accelerate the rate of developing new technologies, increase the probability of their success and provide new methods for the private sector to use in commercial applications, conclude Winslow et al.