Bergius process

The Bergius Process is a method of production of liquid hydrocarbons for use as synthetic fuel by hydrogenation of high-volatile bituminous coal at high temperature and pressure. It was first developed by Friedrich Bergius in 1913, in 1931 Bergius was awarded the Nobel Prize in Chemistry for his development of high pressure chemistry.^[1]

Process

The coal is finely ground and dried in a stream of hot gas. The dry product is mixed with heavy oil recycled from the process. Catalyst is typically added to the mixture. A number of catalysts have been developed over the years, including tungsten or molybdenum sulfides, tin or nickel oleate, and others. Alternatively, iron sulphides present in the coal may have sufficient catalytic activity for the process, which was the original Bergius process.

The mixture is pumped into a reactor. The reaction occurs at between 400 to 500 °C and 20 to 70 MPa hydrogen pressure. The reaction produces heavy oils, middle oils, gasoline, and gases. The overall reaction can be summarized as follows:

$n{\rm C} + (n - x + 1){\rm H}_2 \rarr {\rm C}_n{\rm H}_{2n - 2x + 2}$ (where x = Degrees of Unsaturation)

The immediate product from the reactor must be stabilized by passing it over a conventional hydrotreating catalyst. The product stream is high in naphthenes and aromatics, low in paraffins and very low in olefins. The different fractions can be passed to further processing (cracking, reforming) to output synthetic fuel of desirable quality. If passed through a process such as Platforming, most of the naphthenes are converted to aromatics and the recovered hydrogen recycled to the process. The liquid product from Platforming will contain over 75% aromatics and has a RON^{[clarification needed]} of over 105.

Overall, about 97% of input carbon fed directly to the process can be converted into synthetic fuel. However, any carbon used in generating hydrogen will be lost as carbon dioxide, so reducing the overall carbon efficiency of the process.

There is a residue of unreactive tarry compounds mixed with ash from the coal and catalyst. To minimise the loss of carbon in the residue stream, it is necessary to have a low-ash feed. Typically the coal should be <10% ash by weight. The hydrogen required for the process can be also produced from coal or the residue by steam reforming. A typical hydrogen demand is ~8 kg hydrogen per ton of dry, ash-free coal. Generally, this process is similar to hydrogenation. The output is at three levels: heavy oil, middle oil, gasoline. The middle oil is hydrogenated in order to get more gasoline and the heavy oil is mixed with the coal again and the process restarts. In this way, heavy oil and middle oil fractions are also reused in this process.

History

Friedrich Bergius developed the process during his habilitation. A techniques for the high-pressure and high-temperature chemistry of carbon-containing substrates yielded in a patent in 1913. In this process liquid hydrocarbons used as synthetic fuel are produced by hydrogenation of lignite (brown coal). He developed the process well before the commonly-known Fischer-Tropsch process. Karl Goldschmidt invited him to build an industrial plant at his factory the Th. Goldschmidt AG (now known as Evonik Industries) in 1914.^[2] The production began only in 1919, after the World War I ended, when the need for fuel was already declining. The technical problems, inflation and the constant criticism of Franz Joseph Emil Fischer, which changed to support after a personal demonstration of the process, made the progress slow and Bergius sold his patent to BASF, where Carl Bosch worked on it. Before World War II several plants where built with an annual capacity of 4 million tons of synthetic fuel. These plants were extensively used during World War II to supply Germany with fuel and lubricants.^[3]

Use

Ruins of coal elevator in a synthetic gasoline plant from WWII (IG Farben Industrie Police, Poland)

The Bergius process was extensively used by Nazi Germany and targeted for bombing during the Oil Campaign of World War II. At present there are no plants operating the Bergius Process or its derivatives commercially. The largest demonstration plant was the 200 ton per day plant at Bottrop, Germany, operated by Ruhrkohle, which ceased operation in 1993. There are reports ^[4] of the Chinese company constructing a plant with a capacity of 4 000 ton per day. It was expected to become operational in 2007,^[5] but there has been no confirmation that this was achieved.

During WWII the United States conducted secret research in converting coal to gasoline at a facility in Louisiana, Missouri. Located along the Mississippi river, this plant was producing gasoline in commercial quantities by 1948. The Louisiana process method produced automobile gasoline comparable in price with petroleum based gasoline^[6] but of a higher quality.^{[citation needed]} The facility was shut down in 1953 by the Eisenhower administration after intense lobbying by the oil industry.^[7] Declassified documents detailing the experiments and the production process were systematically destroyed. In the 1980s 16mm microfilm of these documents were discovered in a few Federal Depository Libraries. Within three months researcher requests to view this microfilm were told the canisters were missing. In one case a physical search turned up only the rusty pattern of a 16mm film canister on a steel shelf.^[8]

See also

• Synthetic Liquid Fuels Program
• Fischer-Tropsch process
• Karrick process

References

1. ^ Bergius, Friedrich (May 21, 1932). "Chemical reactions under high pressure". Nobel Foundation. http://nobelprize.org/nobel_prizes/chemistry/laureates/1931/bergius-lecture.pdf. Retrieved 2009-01-23. 
2. ^ "Degussa Geschichte - Friedrich Bergius". http://www.degussa-history.com/geschichte/en/personalities/friedrich_bergius/. Retrieved 2009-11-10. 
3. ^ Stranges, Anthony N. (1984). "Friedrich Bergius and the Rise of the German Synthetic Fuel Industry". Isis (The History of Science Society) 75 (4): 643–667. JSTOR 232411. 
4. ^ [1]^{[dead link]}
5. ^ China's first coal liquefaction scheduled to ease import burden, UPDATED: 10:28, January 24, 2005, People's Daily Online
6. ^ [Personal communication with program Research Chemist]
7. ^ NGA
8. ^ Energy Policy in America since 1945

External links

• The Early Days of Coal Research, U.S. Department of Energy webpage