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Carbochemistry is the branch of chemistry that studies the transformation of coal-(bituminous coal, coal tar, anthracite, lignite, graphite, and charcoal) into useful products and raw materials. [1] The processes that are used in carbochemistry include degasification processes such as carbonization and coking, gasification processes, and liquefaction processes. [2]



The beginning of carbochemistry goes back to the 16th century. At that time, large quantities of charcoal were needed for the smelting of iron ores. Since the production of charcoal required large amounts of slowly-regenerating wood, the use of coal was studied. The use of pure coal was difficult because of the amount of liquid and solid by-products that were generated. In order to improve the handling the coal was initially treated as wood in kilns to produce coke.

Around 1684, John Clayton discovered that coal gas generated from coal was combustible. He described his discovery in the Philosophical Transactions of the Royal Society . [3] [4]

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<span class="mw-page-title-main">Coke (fuel)</span> Hard fuel containing mostly carbon

Coke is a grey, hard, and porous coal-based fuel with a high carbon content and few impurities, made by heating coal or oil in the absence of air—a destructive distillation process. It is an important industrial product, used mainly in iron ore smelting, but also as a fuel in stoves and forges when air pollution is a concern.

<span class="mw-page-title-main">Producer gas</span>

Producer gas is fuel gas that is manufactured by blowing a coke or coal with air and steam simultaneously. It mainly consists of carbon monoxide (CO), hydrogen (H2), as well as substantial amounts of nitrogen (N2). The caloric value of the producer gas is low (mainly because of its high nitrogen content), and the technology is obsolete. Improvements over producer gas, also obsolete, include water gas where the solid fuel is treated intermittently with air and steam and, far more efficiently synthesis gas where the solid fuel is replaced with methane.

<span class="mw-page-title-main">Pyrolysis</span> Thermal decomposition of materials at elevated temperatures in an inert atmosphere

The pyrolysis process is the thermal decomposition of materials at elevated temperatures in an inert atmosphere. It involves a change of chemical composition. The word is coined from the Greek-derived elements pyro "fire", "heat", "fever" and lysis "separating".

<span class="mw-page-title-main">Gasification</span> Form of energy conversion

Gasification is a process that converts biomass- or fossil fuel-based carbonaceous materials into gases, including as the largest fractions: nitrogen (N2), carbon monoxide (CO), hydrogen (H2), and carbon dioxide (CO2). This is achieved by reacting the feedstock material at high temperatures (typically >700 °C), without combustion, via controlling the amount of oxygen and/or steam present in the reaction. The resulting gas mixture is called syngas (from synthesis gas) or producer gas and is itself a fuel due to the flammability of the H2 and CO of which the gas is largely composed. Power can be derived from the subsequent combustion of the resultant gas, and is considered to be a source of renewable energy if the gasified compounds were obtained from biomass feedstock.

<span class="mw-page-title-main">Blast furnace</span> Type of furnace used for smelting to produce industrial metals

A blast furnace is a type of metallurgical furnace used for smelting to produce industrial metals, generally pig iron, but also others such as lead or copper. Blast refers to the combustion air being "forced" or supplied above atmospheric pressure.

Coal gas is a flammable gaseous fuel made from coal and supplied to the user via a piped distribution system. It is produced when coal is heated strongly in the absence of air. Town gas is a more general term referring to manufactured gaseous fuels produced for sale to consumers and municipalities.

<span class="mw-page-title-main">Activated carbon</span> Form of carbon processed to have small, low-volume pores that increase the surface area

Activated carbon, also called activated charcoal, is a form of carbon commonly used to filter contaminants from water and air, among many other uses. It is processed (activated) to have small, low-volume pores that increase the surface area available for adsorption or chemical reactions. Activation is analogous to making popcorn from dried corn kernels: popcorn is light, fluffy, and has a surface area that is much larger than the kernels. Activated is sometimes replaced by active.

<span class="mw-page-title-main">Solid fuel</span>

Solid fuel refers to various forms of solid material that can be burnt to release energy, providing heat and light through the process of combustion. Solid fuels can be contrasted with liquid fuels and gaseous fuels. Common examples of solid fuels include wood, charcoal, peat, coal, hexamine fuel tablets, dry dung, wood pellets, corn, wheat, rye, and other grains. Solid fuels are extensively used in rocketry as solid propellants. Solid fuels have been used throughout human history to create fire and solid fuel is still in widespread use throughout the world in the present day.

<span class="mw-page-title-main">Dry distillation</span>

Dry distillation is the heating of solid materials to produce gaseous products. The method may involve pyrolysis or thermolysis, or it may not.

Coal gasification is the process of producing syngas—a mixture consisting primarily of carbon monoxide (CO), hydrogen (H2), carbon dioxide (CO2), methane (CH4), and water vapour (H2O)—from coal and water, air and/or oxygen.

<span class="mw-page-title-main">Destructive distillation</span>

Destructive distillation is a chemical process in which decomposition of unprocessed material is achieved by heating it to a high temperature; the term generally applies to processing of organic material in the absence of air or in the presence of limited amounts of oxygen or other reagents, catalysts, or solvents, such as steam or phenols. It is an application of pyrolysis. The process breaks up or 'cracks' large molecules. Coke, coal gas, gaseous carbon, coal tar, ammonia liquor, and coal oil are examples of commercial products historically produced by the destructive distillation of coal.

<span class="mw-page-title-main">Tar</span> Dark viscous organic liquid

Tar is a dark brown or black viscous liquid of hydrocarbons and free carbon, obtained from a wide variety of organic materials through destructive distillation. Tar can be produced from coal, wood, petroleum, or peat.

Carbonization is the conversion of organic matters like plants and dead animal remains into carbon through destructive distillation.

<span class="mw-page-title-main">Petroleum coke</span> Solid carbon-rich material

Petroleum coke, abbreviated 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 oil sands and from Venezuela's Orinoco oil sands.

<span class="mw-page-title-main">Karrick process</span>

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.

Pyrolysis oil, sometimes also known as bio-crude or bio-oil, is a synthetic fuel under investigation as substitute for petroleum. It is obtained by heating dried biomass without oxygen in a reactor at a temperature of about 500 °C (900 °F) with subsequent cooling. Pyrolysis oil is a kind of tar and normally contains levels of oxygen too high to be considered a pure hydrocarbon. This high oxygen content results in non-volatility, corrosiveness, immiscibility with fossil fuels, thermal instability, and a tendency to polymerize when exposed to air. As such, it is distinctly different from petroleum products. Removing oxygen from bio-oil or nitrogen from algal bio-oil is known as upgrading.

<span class="mw-page-title-main">Smokeless fuel</span>

Smokeless fuel is a type of solid fuel which either does not emit visible smoke, or emits minimal amounts, during combustion. These types of fuel are becoming increasingly popular in areas which ban the use of coal and other fuels such as unseasoned or wet wood which produce much smoke. Open fires are still popular with many domestic consumers, especially for those living in older houses where open fireplaces have not been removed or replaced by stoves for example. Many houses older than about 1970 are fitted with open fireplaces when coal was in widespread use for domestic heating. However, modern houses are rarely equipped with fireplaces and central heating with natural gas or electricity is the usual choice.

<span class="mw-page-title-main">Fuel</span> Energy released from a source

A fuel is any material that can be made to react with other substances so that it releases energy as thermal energy or to be used for work. The concept was originally applied solely to those materials capable of releasing chemical energy but has since also been applied to other sources of heat energy, such as nuclear energy.

<span class="mw-page-title-main">Charcoal</span> Lightweight black carbon residue

Charcoal is a lightweight black carbon residue produced by strongly heating wood in minimal oxygen to remove all water and volatile constituents. In the traditional version of this pyrolysis process, called charcoal burning, often by forming a charcoal kiln, the heat is supplied by burning part of the starting material itself, with a limited supply of oxygen. The material can also be heated in a closed retort. Modern "charcoal" briquettes used for outdoor cooking may contain many other additives, e.g. coal.

<span class="mw-page-title-main">Charcoal pile</span> Covered fire for producing charcoal

A charcoal pile or charcoal clamp is a carefully arranged pile of wood, covered by turf or other layer, inside which a fire is lit in order to produce charcoal. The pile is tended by a charcoal burner. It is similar to a charcoal kiln, but the latter is usually a permanent structure made of materials such as stone.


  1. Diez, María Antonia; Garcia, Roberto (2019-01-01), Suárez-Ruiz, Isabel; Diez, Maria Antonia; Rubiera, Fernando (eds.), "15 - Coal tar: a by-product in cokemaking and an essential raw material in carbochemistry", New Trends in Coal Conversion, Woodhead Publishing, pp. 439–487, doi:10.1016/b978-0-08-102201-6.00015-7, ISBN   978-0-08-102201-6 , retrieved 2022-11-15
  2. Dumon, R. (1977-11-01). "Coal and carbochemistry". Ind. Pet.; (France) (in French). 488.
  3. An Experiment concerning the Spirit of Coals, by John Clayton, Philosophical Transactions, 1735, No. 452, S. 59
  4. Walter T. Layton: The Discoverer of Gas Lighting: Notes on the Life and Work of the Rev. John Clayton, D.D., 1657–1725. London, 1926

See also