Carbonization
Encyclopedia
Carbonization or carbonisation is the term for the conversion of an organic substance into carbon
or a carbon-containing residue through pyrolysis
or destructive distillation
. It is often used in organic chemistry
with reference to the generation of coal gas
and coal tar
from raw coal
. Fossil fuels in general are the products of the carbonization of vegetable matter.
Carbonization is often exothermic
, which means that it could in principle be made self-sustaining and be used as a source of energy that does not produce carbon dioxide
. (See .) In the case of glucose
, the reaction releases about 237 calories per gram.
When biomaterial
is exposed to sudden searing heat (as in the case of an atomic bomb explosion or pyroclastic flow
from a volcano
, for instance), it can be carbonized extremely quickly, turning it into solid carbon. In the destruction of Herculaneum
by a volcano, many organic objects such as furniture were carbonized by the intense heat.
In one study, carbonization was used to create a new catalyst for the generation of biodiesel
from ethanol
and fatty acid
s. The catalyst was created by carbonization of simple sugar
s such as glucose
and sucrose
. The sugars were processed for 15 hours at 400 °C under a nitrogen flow to a black carbon residue consisting of a complex mixture of polycyclic
aromatic carbon sheets. This material was then treated with sulfuric acid
, which functionalized the sheets with sulfonite, carboxyl, and hydroxyl
catalytic sites.
Carbon
Carbon is the chemical element with symbol C and atomic number 6. As a member of group 14 on the periodic table, it is nonmetallic and tetravalent—making four electrons available to form covalent chemical bonds...
or a carbon-containing residue through pyrolysis
Pyrolysis
Pyrolysis is a thermochemical decomposition of organic material at elevated temperatures without the participation of oxygen. It involves the simultaneous change of chemical composition and physical phase, and is irreversible...
or destructive distillation
Destructive distillation
Destructive distillation is the chemical process involving the decomposition of feedstock by heating 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,...
. It is often used in organic chemistry
Organic chemistry
Organic chemistry is a subdiscipline within chemistry involving the scientific study of the structure, properties, composition, reactions, and preparation of carbon-based compounds, hydrocarbons, and their derivatives...
with reference to the generation of coal gas
Coal gas
Coal gas is a flammable gaseous fuel made by the destructive distillation of coal containing a variety of calorific gases including hydrogen, carbon monoxide, methane and volatile hydrocarbons together with small quantities of non-calorific gases such as carbon dioxide and nitrogen...
and coal tar
Coal tar
Coal tar is a brown or black liquid of extremely high viscosity, which smells of naphthalene and aromatic hydrocarbons. Coal tar is among the by-products when coal iscarbonized to make coke or gasified to make coal gas...
from raw coal
Coal
Coal is a combustible black or brownish-black sedimentary rock usually occurring in rock strata in layers or veins called coal beds or coal seams. The harder forms, such as anthracite coal, can be regarded as metamorphic rock because of later exposure to elevated temperature and pressure...
. Fossil fuels in general are the products of the carbonization of vegetable matter.
Carbonization is often exothermic
Exothermic
In thermodynamics, the term exothermic describes a process or reaction that releases energy from the system, usually in the form of heat, but also in the form of light , electricity , or sound...
, which means that it could in principle be made self-sustaining and be used as a source of energy that does not produce carbon dioxide
Carbon dioxide
Carbon dioxide is a naturally occurring chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom...
. (See .) In the case of glucose
Glucose
Glucose is a simple sugar and an important carbohydrate in biology. Cells use it as the primary source of energy and a metabolic intermediate...
, the reaction releases about 237 calories per gram.
When biomaterial
Biomaterial
A biomaterial is any matter, surface, or construct that interacts with biological systems. The development of biomaterials, as a science, is about fifty years old. The study of biomaterials is called biomaterials science. It has experienced steady and strong growth over its history, with many...
is exposed to sudden searing heat (as in the case of an atomic bomb explosion or pyroclastic flow
Pyroclastic flow
A pyroclastic flow is a fast-moving current of superheated gas and rock , which reaches speeds moving away from a volcano of up to 700 km/h . The flows normally hug the ground and travel downhill, or spread laterally under gravity...
from a volcano
Volcano
2. Bedrock3. Conduit 4. Base5. Sill6. Dike7. Layers of ash emitted by the volcano8. Flank| 9. Layers of lava emitted by the volcano10. Throat11. Parasitic cone12. Lava flow13. Vent14. Crater15...
, for instance), it can be carbonized extremely quickly, turning it into solid carbon. In the destruction of Herculaneum
Herculaneum
Herculaneum was an ancient Roman town destroyed by volcanic pyroclastic flows in AD 79, located in the territory of the current commune of Ercolano, in the Italian region of Campania in the shadow of Mt...
by a volcano, many organic objects such as furniture were carbonized by the intense heat.
In one study, carbonization was used to create a new catalyst for the generation of biodiesel
Biodiesel
Biodiesel refers to a vegetable oil- or animal fat-based diesel fuel consisting of long-chain alkyl esters. Biodiesel is typically made by chemically reacting lipids with an alcohol....
from ethanol
Ethanol
Ethanol, also called ethyl alcohol, pure alcohol, grain alcohol, or drinking alcohol, is a volatile, flammable, colorless liquid. It is a psychoactive drug and one of the oldest recreational drugs. Best known as the type of alcohol found in alcoholic beverages, it is also used in thermometers, as a...
and fatty acid
Fatty acid
In chemistry, especially biochemistry, a fatty acid is a carboxylic acid with a long unbranched aliphatic tail , which is either saturated or unsaturated. Most naturally occurring fatty acids have a chain of an even number of carbon atoms, from 4 to 28. Fatty acids are usually derived from...
s. The catalyst was created by carbonization of simple sugar
Sugar
Sugar is a class of edible crystalline carbohydrates, mainly sucrose, lactose, and fructose, characterized by a sweet flavor.Sucrose in its refined form primarily comes from sugar cane and sugar beet...
s such as glucose
Glucose
Glucose is a simple sugar and an important carbohydrate in biology. Cells use it as the primary source of energy and a metabolic intermediate...
and sucrose
Sucrose
Sucrose is the organic compound commonly known as table sugar and sometimes called saccharose. A white, odorless, crystalline powder with a sweet taste, it is best known for its role in human nutrition. The molecule is a disaccharide composed of glucose and fructose with the molecular formula...
. The sugars were processed for 15 hours at 400 °C under a nitrogen flow to a black carbon residue consisting of a complex mixture of polycyclic
Polycyclic aromatic hydrocarbon
Polycyclic aromatic hydrocarbons , also known as poly-aromatic hydrocarbons or polynuclear aromatic hydrocarbons, are potent atmospheric pollutants that consist of fused aromatic rings and do not contain heteroatoms or carry substituents. Naphthalene is the simplest example of a PAH...
aromatic carbon sheets. This material was then treated with sulfuric acid
Sulfuric acid
Sulfuric acid is a strong mineral acid with the molecular formula . Its historical name is oil of vitriol. Pure sulfuric acid is a highly corrosive, colorless, viscous liquid. The salts of sulfuric acid are called sulfates...
, which functionalized the sheets with sulfonite, carboxyl, and hydroxyl
Hydroxyl
A hydroxyl is a chemical group containing an oxygen atom covalently bonded with a hydrogen atom. In inorganic chemistry, the hydroxyl group is known as the hydroxide ion, and scientists and reference works generally use these different terms though they refer to the same chemical structure in...
catalytic sites.