The Beginning of the Synthetic Fuel Industry

Coal was hydrogenated in the laboratory by Berthelot as early as 1869 [47]. The reaction was carried out with hydriodic acid at 520° F for 24 hours, and a 67% yield of oil containing aromatics and naphthenes was obtained. Major advances were made by the Germans in the early 1900s. Germany, a country with abundant coal reserves but virtually no petroleum deposits, was becoming increasingly dependent on gasoline and diesel engines. To ensure that Germany would never lack a plentiful supply of liquid fuels, German scientists and engineers invented and developed two processes that enabled them to produce synthetic petroleum from their coal supplies and to establish the world's first technologically successful synthetic liquid fuel industry [48]. In 1911, Friedrich Bergius obtained oil by hydrogenating coal without a catalyst under hydrogen pressure at 570 to 660°F. In 1913, he applied for the first patent on coal hydrogenation, and in 1931 he was awarded the Nobel Prize in Chemistry [19,47]. Bergius also observed that coal paste could be injected readily into a vessel under pressure. The role of catalysts in the hydrogenation of coal was not realized until later.

At the end of 1925, I.G. Farben, a chemical company, hydrogenated coal using a molybdenum oxide catalyst. The presence of the catalyst allowed the hydrogenation of coal in the presence of excess hydrogen at low pressure and at temperatures of 750 to 840°F. In the following year, I.G. Farben conducted the liquefaction process in two steps because high-molecular-weight materials in the intermediate hydrogenation product fouled the catalyst. Coal was mixed with the catalyst and hydrogenated in the liquid phase to middle oil, which was further hydrogenated to gasoline in vapor phase over a fixed bed of catalyst [47].

About 10 years after Bergius began his work, Franz Fischer and Hans Tropsch at the Kaiser-Wilhelm Institute for Coal Research in Mülheim, invented a second process for the synthesis of liquid fuel from coal [48]. By the mid-1930s, I.G. Farben and other chemical companies such as Ruhrchemie had started to industrialize synthetic liquid fuel production, resulting in the construction of 12 coal hydrogenation and 9 Fischer-Tropsch plants by the time World War II ended. The processes were complementary in that coal hydrogenation produced high-quality aviation and motor gasoline, while

Fischer-Tropsch syntheses produced diesel and lubricating oil, waxes, and some lower quality motor gasoline [48].

Germany's successful synthetic fuel industry continued to grow through the 1930s, and from 1939 to 1945 it produced 18 million metric tons of liquids from coal and tar, and another three million metric tons of liquids from Fischer-Tropsch synthesis [48]. Neither coal-to-oil process could produce a synthetic liquid fuel at a cost competitive with natural petroleum; however, they persevered because they provided the only path Germany could follow in its search for petroleum independence.

Similarly, South Africa, fearing boycott as a result of their racial policies, decided to proceed with a synthetic fuels plant in 1951, although this process would produce liquid fuels that were more expensive than petroleum refined products. The South Africans selected Fischer-Tropsch technology because the Germans had successfully used it and because direct liquefaction had not been used on a scale that was as large as the South Africans were planning [22]. This led to the creation of Sasol and government subsidies that exist even today [49]. However, now that Sasol has the equipment in place, crude oil is readily available, and apartheid has been abolished, political and economic considerations have forced the South African government to phase out the subsidy for transportation fuels. Sasol anticipated losing its subsidies and has gradually shifted its emphasis from producing only transportation fuels to deriving a significant fraction of its profits from the sale of chemicals and petrochemical feedstocks [49]. Plants were constructed in South Africa in three stages: 1955, 1982, and 1992 (see Table 5-8) and are discussed later in this chapter. All three of these plants are currently operating.

In the United States, interest in converting coal to liquid products has been cyclic and affected by the cost and availability of petroleum. In the beginning of the industrial revolution, coal was the major source of energy in the United States and continued to dominate the U.S. energy supply for the next 100 years. Petroleum, however, quickly became the preferred energy source after its discovery in Pennsylvania in 1859 and rapid commercial production in the early 1900s. By the early 1920s, worries that oil supplies were becoming depleted along with an expanding automobile industry resulted in a short-lived interest in coal liquefaction; when oil was discovered in Texas in the mid-1920s, further interest in coal liquefaction ceased. After World War II, consumption of petroleum and natural gas in the United States exceeded that of coal, the United States experienced petroleum shortages, and coal liquefaction was again considered as an alternative. A sizeable research effort resulted, but discovery of massive petroleum reserves in the Middle East in the mid-1940s once again made coal liquefaction an uneconomical alternative. In 1972, the U.S. petroleum production began to decline and unrest developed in the Middle East. The limited availability of domestic supplies of natural gas and crude oil and the desire to reduce the country's dependence on foreign sources of energy led to significant liquefaction research by the federal government, private industry, and universities. The major processes are discussed below.

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