management of large, complex systems as practiced by established industries in similar situations. Large refineries are one good example of well-developed systems that manufacture many products: in producing and exporting power, they optimize around downtime or changing performance characteristics of key components or changing feedstock specifications.

Recommendation. Systems modeling capability should be an integral aspect of the Vision 21 Program. It is important for the Vision 21 project management as well as the entire project team to interact regularly with the modeling team. A process should be created in the Vision 21 Program for regular interaction of all of technology development teams and project management with the engineering modeling team to review and understand the overall system models and the cost implications of specific technology issues. This process should be utilized to create new process and technology concepts.

CONVERSION OF SYNTHESIS GAS TO FUELS AND CHEMICALS

Introduction

Commercial production of liquid fuels from coal-derived synthesis gas (syngas) was started in the mid-1950s in South Africa. The basis for this industrial complex was the pioneering work done by Franz Fischer, H. Tropsch, and others in Europe in the earlier part of the 20th century. The economic driver for this technology commercialization was the desire to make fuels from the abundant coal resources in the country. The need for this technology was reinforced later on by the embargo on trade with South Africa by most other nations. Pilot-scale demonstrations of coal-based Fischer-Tropsch (F-T) fuels have also taken place in the United States, Japan, and Russia. Moreover, before and during World War II, significant quantities of F-T fuels were made in Germany from coal.

The catalyst of choice for coal-derived syngas conversion to F-T fuels is iron, with promoters added for reduced attrition of catalysts, sintering, and increased reactivity. Reactor technology has evolved from early fixed-bed reactors to the preferred option today, three-phase (gas, liquid, and solid catalyst) liquid fluidized reactors. Coal-based syngas is also used to make other important industrial products, including methanol and hydrogen. The technology has improved along the same time line. The catalyst of choice for methanol is copper, and for hydrogen production, nickel. The preferred reactors are fixed-bed or tubular reactors.

While the technology for making fuels and chemicals is widely available and has been commercially demonstrated, only a small fraction of overall production is from coal-derived syngas. The main reasons are the higher cost of making syngas from coal than from natural gas and the lower molar ratio (<1.0) of hydrogen to carbon monoxide produced in coal gasifiers. Production of syngas



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