Hydrocarbons liquid, from coal

On a commercial scale, the low-tanperature carbonization of coal was employed extensively in the industrialized nations of Europe but suffered a major decline after 1945 as oil and natural gas became more widely available, but the subsequent rapid escalation in oil prices as well as newer and more restrictive environmental regulations have stimulated (and reactivated) interest in the recovery of hydrocarbon liquids from coal by low-temperature thermal processing. 

Lanning, W. C. Green, J. B. Dooley, J. E. The Preparation of Liquids from Coals for Hydrocarbon-Type Analysis in Relation to Refining. DOE/BETC/RI-78/10, 1978, 27 pp. 

BERC has undertaken a systematic study which includes the preparation at mild reaction conditions of liquids from coals which vary widely in rank and quality. The liquids so obtained will be characterized and analyzed for hydrocarbon type by BERC procedures, and the data will be used to supplement the characterization studies in progress on other syncrudes. A preliminary report will be made on the progress of this work to date. 

The lipid-rich portions of coal are generally regarded as the source of the liquid hydrocarbons derived from coal (Snowdon, 1991). This hpid-rich fraction includes higher plant waxes and resins, as well as algal lipids admixed with the vascular plant materials. The element composition of coal is a key factor in determining its oilgenerating potential. Generally, coals are... 

Liquid hydrocarbons derived from coal have a composition that is somewhat distinctive, and that distinguishes them from oils derived from algal-dominated type I and II source rocks. For example, petroleum derived from coal tends to have high pristane/phytane ratios a ratio >4 is... 

Liquid fuels are made from coal by reacting the coal with hydrogen gas under high pressure in the presence of catalysts (hydrogenating the coal). The process produces hydrocarbons like those in petroleum. The resulting crude oil type of material can be fractionally distilled to give fuel oil, gasoline, and certain hydrocarbons used in the manufacture of plastics, medicines, and other commodities. About 5.5 barrels of liquid are produced for each ton of coal. At the present time, the cost of a barrel of liquid from coal liquefaction is about double that of a barrel of crude oil. However, as petroleum supplies diminish and the cost of crude oil increases, coal liquefaction will become economically feasible. 

Liquid Fuels via Methanol Synthesis and Conversion. Methanol is produced catalyticaHy from synthesis gas. By-products such as ethers, formates, and higher hydrocarbons are formed in side reactions and are found in the cmde methanol product. Whereas for many years methanol was produced from coal, after World War II low cost natural gas and light petroleum fractions replaced coal as the feedstock. 

Benzene An aromatic hydrocarbon which is a colorless, volatile, flammable liquid. Benzene is obtained chiefly from coal tar and is used as a solvent for resins and fats in dye manufacture. 

Synthesis gas consists of a nonhydrocarhon mixture (H2,CO) ohtain-ahle from more than one source. It is included in this chapter and is further noted in Chapter 5 in relation to methane as a major feedstock for this mixture. This chapter discusses the use of synthesis gas obtained from coal gasification and from different petroleum sources for producing gaseous as well as liquid hydrocarbons (Fischer Tropsch synthesis). 

It is possible to produce some liquid hydrocarbons from most coals during conversion (pyrolysis and hydrogenation/ catalytic and via solvent refining)/ but the yield and hydrogen consumption required to achieve this yield can vary widely from coal to coal. The weight of data in the literature indicate that the liquid hydrocarbons are derived from the so-called reactive maceralS/ i.e. the vitrinites and exinites present (7 8 1 9). Thusf for coals of the same rank the yield of liquids during conversion would be expected to vary with the vitrinite plus exinite contents. This leads to the general question of effect of rank on the response of a vitrinite and on the yield of liquid products and/ in the context of Australian bituminous coals, where semi-fusinite is usually abundant/ of the role of this maceral in conversion. 

General name for mixtures of liquid hydrocarbons obtained from petroleum, coal tar or shale, used as solvents for unvulcanised rubber. 

Both the production of hydrogen from coal and the production of oil from unconventional resources (oil sands, oil shale, CTL, GTL) result in high C02 emissions and substantially increase the carbon footprint of fuel supply, unless the C02 is captured and stored. While the capture of C02 at a central point source is equally possible for unconventionals and centralised hydrogen production, in the case of hydrogen, a C02-free fuel results, unlike in the case of liquid hydrocarbon fuels. This is all the more important, as around 80% of the WTW C02 emissions result from the fuel use in the vehicles. If CCS were applied to hydrogen production from biomass, a net C02 removal from the atmosphere would even be achievable. 

Approximately 30% of total hydrogen production comes from heavy oil and 20% from coal [6]. Lighter liquid hydrocarbons are - after desulfurization - also converted by steam reforming on nickel catalysts. The downstream treatment of syngas is the same as for natural gas. 

The hydroformylation of alkenes was accidentally discovered by Roelen while he was studying the Fischer-Tropsch reaction (syn-gas conversion to liquid fuels) with a heterogeneous cobalt catalyst in the late thirties. In a mechanistic experiment Roelen studied whether alkenes were intermediates in the "Aufbau" process of syn-gas (from coal, Germany 1938) to fuel. He found that alkenes were converted to aldehydes or alcohols containing one more carbon atom. It took more than a decade before the reaction was taken further, but now it was the conversion of petrochemical hydrocarbons into oxygenates that was desired. It was discovered that the reaction was not catalysed by the supported cobalt but in fact by HCo(CO)4 which was formed in the liquid state. 

The first step toward making liquid fuels from coal involves the manufacture of synthesis gas (CO and H ) from coal. In 1925, Franz Fischer and Hans Tropsch developed a catalyst that converted CO and at 1 atm and 250 to 300°C into liquid hydrocarbons. By 1941, Fischer-Tropsch plants produced 740 000 tons of petroleum products per year in Germany (Dry, 1999). Fischer-Tropsch technology is based on a complex series of reactions that use to reduce CO to CH groups linked to form long-chain hydrocarbons (Schulz, 1999) ... 

Dynaphen A process for converting mixed alkyl phenols (from coal liquids or lignin) to benzene, phenol, and fuel gas, by noncatalytic hydrogenation at high temperature. Developed and offered by Hydrocarbon Research. 

The chemistry of a third group of conversion techniques -i.e., partial conversion methods which skim hydrocarbon gases and/or liquids from the coal and leave a char suitable for use as a boiler fuel or gasification feedstock - is. If anything, even more speculative than the chemistry of liquefaction. 

An enormous amount of work both at bench scale and at pilot plant scale have been conducted to study the production of liquid and gaseous hydrocarbons from coal. Since most of the analytical methods are either very time consuming or very specialized, almost all the data available on the coal liquefaction process are based on distillation data or on the assumption that all products which are not insoluble solids are converted. It is known that products of liquefaction vary based on coal, reaction conditions, and media of reaction hence, conversion and yield may be based on very different products. 

Shale Oil. In the United States, shale oil, or oil derivable from oil shale, represents the largest potential source of liquid hydrocarbons that can be readily processed to fuel liquids similar to those derived from natural petroleum. Some countries produce liquid fuels from oil shale. There is no such industry in the United States although more than 50 companies were producing oil from coal and shale in the United States in 1860 (152,153), and after the oil embargo of 1973 several companies reactivated shale-oil process development programs (154,155). Petroleum supply and price stability has since severely curtailed shale oil development. In addition, complex environmental issues (156) further prohibit demonstration of commercial designs. 

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