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]
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. A catalyst is typically added to the mixture. A number of catalysts have been developed over the years, including tungsten or molybdenum disulfide, tin or nickel oleate, and others. Alternatively, iron sulfide present in the coal may have sufficient catalytic activity for the process, which was the original Bergius process. [2]
The mixture is pumped into a reactor. The reaction occurs at between 400 and 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:
The immediate product from the reactor must be stabilized by passing it over a conventional hydrotreating catalyst. The product stream is high in cycloalkanes and aromatics, low in alkanes (paraffins) and very low in alkenes (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 cycloalkanes 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 Research Octane Number (RON) 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 ~80 kg [ citation needed ] 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.
The most recent evolution of Bergius' work is the 2-stage hydroliquefaction plant at Wilsonville AL which operated during 1981-85. Here a coal extract was prepared under heat and hydrogen pressure using finely pulverized coal and recycle donor solvent. As the coal molecule is broken down, free radicals are formed which are immediately stabilized by absorption of H atoms from the donor solvent. Extract then passes to a catalytic ebullated-bed hydrocracker (H-Oil unit) fed by additional hydrogen, forming lower molecular weight hydrocarbons and splitting off sulfur, oxygen and nitrogen originally present in the coal. Part of the liquid product is hydrogenated donor solvent which is returned to Stage I. The balance of liquid product is fractionated by distillation yielding various boiling range products and an ashy residue. Ashy residue goes to a Kerr-McGee critical solvent deashing unit which yields additional liquid product and a high-ash material containing unreacted coal and heavy residuum, which in a commercial plant would be gasified to make the H2 needed to feed the process. Parameters can be adjusted to avoid directly gasifying any of the coal entering the plant. Alternative versions of the plant configuration could use L-C Fining and/or an antisolvent deashing unit. Typical species in the donor solvent are fused-ring aromatics (tetrahydronaphthalene and up) or the analogous heterocycles.
Friedrich Bergius developed the process during his habilitation. A technique 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. [3] The production began only in 1919, after 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 were 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. [4]
Coal hydrogenation is not used commercially any more. [5]
The Bergius process was extensively used by Brabag, a cartel firm of Nazi Germany. Plants that used the process were 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 [6] of a Chinese company constructing a plant with a capacity of 4 000 ton per day. It was expected to become operational in 2007, [7] but there has been no confirmation that this was achieved.
Towards the end of World War II the United States began heavily financing research into converting coal to gasoline, including money to build a series of pilot plants. The project was enormously helped by captured German technology. [8] One plant using the Bergius process was built in Louisiana, Missouri and began operation about 1946. Located along the Mississippi river, this plant was producing gasoline in commercial quantities by 1948. The Louisiana process method produced automobile gasoline at a price slightly higher than, but comparable to, petroleum-based gasoline [9] but of a higher quality.[ citation needed ] The facility was shut down in 1953 by the Eisenhower administration, allegedly after intense lobbying by the oil industry. [9]
In organic chemistry, an alkane, or paraffin, is an acyclic saturated hydrocarbon. In other words, an alkane consists of hydrogen and carbon atoms arranged in a tree structure in which all the carbon–carbon bonds are single. Alkanes have the general chemical formula CnH2n+2. The alkanes range in complexity from the simplest case of methane, where n = 1, to arbitrarily large and complex molecules, like pentacontane or 6-ethyl-2-methyl-5-(1-methylethyl) octane, an isomer of tetradecane.
In organic chemistry, a hydrocarbon is an organic compound consisting entirely of hydrogen and carbon. Hydrocarbons are examples of group 14 hydrides. Hydrocarbons are generally colourless and hydrophobic; their odor is usually faint, and may be similar to that of gasoline or lighter fluid. They occur in a diverse range of molecular structures and phases: they can be gases, liquids, low melting solids or polymers.
Hydrogenation is a chemical reaction between molecular hydrogen (H2) and another compound or element, usually in the presence of a catalyst such as nickel, palladium or platinum. The process is commonly employed to reduce or saturate organic compounds. Hydrogenation typically constitutes the addition of pairs of hydrogen atoms to a molecule, often an alkene. Catalysts are required for the reaction to be usable; non-catalytic hydrogenation takes place only at very high temperatures. Hydrogenation reduces double and triple bonds in hydrocarbons.
Pyrolysis is the process of thermal decomposition of materials at elevated temperatures, often in an inert atmosphere without access to oxygen.
Friedrich Karl Rudolf Bergius was a German chemist known for the Bergius process for producing synthetic fuel from coal, Nobel Prize in Chemistry in recognition of contributions to the invention and development of chemical high-pressure methods. Having worked with IG Farben during World War II, his citizenship came into question following the war, causing him to ultimately flee to Argentina, where he acted as adviser to the Ministry of Industry.
In petrochemistry, petroleum geology and organic chemistry, cracking is the process whereby complex organic molecules such as kerogens or long-chain hydrocarbons are broken down into simpler molecules such as light hydrocarbons, by the breaking of carbon–carbon bonds in the precursors. The rate of cracking and the end products are strongly dependent on the temperature and presence of catalysts. Cracking is the breakdown of large hydrocarbons into smaller, more useful alkanes and alkenes. Simply put, hydrocarbon cracking is the process of breaking long-chain hydrocarbons into short ones. This process requires high temperatures.
Liquid fuels are combustible or energy-generating molecules that can be harnessed to create mechanical energy, usually producing kinetic energy; they also must take the shape of their container. It is the fumes of liquid fuels that are flammable instead of the fluid. Most liquid fuels in widespread use are derived from fossil fuels; however, there are several types, such as hydrogen fuel, ethanol, and biodiesel, which are also categorized as a liquid fuel. Many liquid fuels play a primary role in transportation and the economy.
The Fischer–Tropsch process (FT) is a collection of chemical reactions that converts a mixture of carbon monoxide and hydrogen, known as syngas, into liquid hydrocarbons. These reactions occur in the presence of metal catalysts, typically at temperatures of 150–300 °C (302–572 °F) and pressures of one to several tens of atmospheres. The Fischer–Tropsch process is an important reaction in both coal liquefaction and gas to liquids technology for producing liquid hydrocarbons.
In industrial chemistry, coal gasification is the process of producing syngas—a mixture consisting primarily of carbon monoxide (CO), hydrogen, carbon dioxide, methane, and water vapour —from coal and water, air and/or oxygen.
Catalytic reforming is a chemical process used to convert naphthas from crude oil into liquid products called reformates, which are premium "blending stocks" for high-octane gasoline. The process converts low-octane linear hydrocarbons (paraffins) into branched alkanes (isoparaffins) and cyclic naphthenes, which are then partially dehydrogenated to produce high-octane aromatic hydrocarbons. The dehydrogenation also produces significant amounts of byproduct hydrogen gas, which is fed into other refinery processes such as hydrocracking. A side reaction is hydrogenolysis, which produces light hydrocarbons of lower value, such as methane, ethane, propane and butanes.
Coal liquefaction is a process of converting coal into liquid hydrocarbons: liquid fuels and petrochemicals. This process is often known as "Coal to X" or "Carbon to X", where X can be many different hydrocarbon-based products. However, the most common process chain is "Coal to Liquid Fuels" (CTL).
Petroleum coke, abbreviated coke, pet coke or petcoke, is a final carbon-rich solid material that derives from oil refining, and is one type of the group of fuels referred to as cokes. Petcoke is the coke that, in particular, derives from a final cracking process—a thermo-based chemical engineering process that splits long chain hydrocarbons of petroleum into shorter chains—that takes place in units termed coker units. Stated succinctly, coke is the "carbonization product of high-boiling hydrocarbon fractions obtained in petroleum processing ". Petcoke is also produced in the production of synthetic crude oil (syncrude) from bitumen extracted from Canada's tar sands and from Venezuela's Orinoco oil sands. In petroleum coker units, residual oils from other distillation processes used in petroleum refining are treated at a high temperature and pressure leaving the petcoke after driving off gases and volatiles, and separating off remaining light and heavy oils. These processes are termed "coking processes", and most typically employ chemical engineering plant operations for the specific process of delayed coking.
Synthetic fuel or synfuel is a liquid fuel, or sometimes gaseous fuel, obtained from syngas, a mixture of carbon monoxide and hydrogen, in which the syngas was derived from gasification of solid feedstocks such as coal or biomass or by reforming of natural gas.
Gas to liquids (GTL) is a refinery process to convert natural gas or other gaseous hydrocarbons into longer-chain hydrocarbons, such as gasoline or diesel fuel. Methane-rich gases are converted into liquid synthetic fuels. Two general strategies exist: (i) direct partial combustion of methane to methanol and (ii) Fischer–Tropsch-like processes that convert carbon monoxide and hydrogen into hydrocarbons. Strategy ii is followed by diverse methods to convert the hydrogen-carbon monoxide mixtures to liquids. Direct partial combustion has been demonstrated in nature but not replicated commercially. Technologies reliant on partial combustion have been commercialized mainly in regions where natural gas is inexpensive.
Fluid catalytic cracking (FCC) is the conversion process used in petroleum refineries to convert the high-boiling point, high-molecular weight hydrocarbon fractions of petroleum into gasoline, alkene gases, and other petroleum products. The cracking of petroleum hydrocarbons was originally done by thermal cracking, now virtually replaced by catalytic cracking, which yields greater volumes of high octane rating gasoline; and produces by-product gases, with more carbon-carbon double bonds, that are of greater economic value than the gases produced by thermal cracking.
The Karrick process is a low-temperature carbonization (LTC) and pyrolysis process of carbonaceous materials. Although primarily meant for coal carbonization, it also could be used for processing of oil shale, lignite or any carbonaceous materials. These are heated at 450 °C (800 °F) to 700 °C (1,300 °F) in the absence of air to distill out synthetic fuels–unconventional oil and syngas. It could be used for a coal liquefaction as also for a semi-coke production. The process was the work of oil shale technologist Lewis Cass Karrick at the United States Bureau of Mines in the 1920s.
Petroleum naphtha is an intermediate hydrocarbon liquid stream derived from the refining of crude oil with CAS-no 64742-48-9. It is most usually desulfurized and then catalytically reformed, which rearranges or restructures the hydrocarbon molecules in the naphtha as well as breaking some of the molecules into smaller molecules to produce a high-octane component of gasoline.
Syngas to gasoline plus (STG+) is a thermochemical process to convert natural gas, other gaseous hydrocarbons or gasified biomass into drop-in fuels, such as gasoline, diesel fuel or jet fuel, and organic solvents.
Decarboxylated and decarbonylated biofuels are renewable hydrocarbon fuels produced by converting biomass, by either decarboxylation or decarbonylation, into liquid transportation fuels, such as ethanol and biodiesel. Conversion of biomass to liquid fuels is preferred as an alternative to the extraction of fossil fuels because biomass removes carbon dioxide from the atmosphere as it grows through photosynthesis. When combusted, this carbon is re-released into the atmosphere, closing the carbon cycle and making biofuels carbon neutral under some conditions. First generation biofuels such as biodiesel are produced directly from crops, such as cereals, maize, sugar beet and cane, and rapeseed. Second generation fuels are produced from byproducts from production of food and other goods, as well as from household waste, used frying oil from restaurants, and slaughterhouse waste.
Exxon donor solvent process (EDS) is a coal liquefaction process developed by Exxon Research and Engineering Company, starting in 1966. The process converts solid coal directly to liquid synthetic fuels which could be used as a substitute for petroleum products. The process does not involve an intermediate step of coal gasification. Exxon operated a pilot plant in Texas from 1980 until 1982.
