What are the coal chemical products?

The process of converting coal into gas, liquid, solid fuel and chemicals by chemical processing with coal as raw material. Mainly includes coal gasification, liquefaction and dry distillation, as well as tar processing and calcium carbide acetylene chemical industry. Coal chemical industry began in the second half of18th century, and a complete coal chemical system was formed in19th century. In the 20th century, many organic chemicals based on agricultural and forestry products were mostly produced by coal, and coal chemical industry became an important part of chemical industry. After World War II, the petrochemical industry developed rapidly, and the production of many chemicals shifted from coal to oil and natural gas, thus weakening the position of coal chemical industry in the chemical industry. When oil prices rose sharply in the 1970s, coal chemical industry once developed (see the development history of coal chemical industry). In the chemical processing of coal, the chemical structure of organic matter in coal is a macromolecular structure with aromatic condensed ring as the unit core and interconnected by bridges and various functional groups (see coal chemistry). Through thermal processing and catalytic processing, coal can be converted into various fuels and chemical products (see chemical utilization methods of coal). Among all kinds of chemical processing of coal, coking is the earliest and still the most important method. Its main purpose is to make metallurgical coke, and at the same time, it produces gas and aromatic hydrocarbons such as benzene, toluene, xylene and naphthalene. Coal gasification also plays an important role in coal chemical industry, which is used to produce city gas and various fuel gases (widely used in machinery, building materials and other industries) and synthetic gas (as raw materials for synthetic ammonia and methanol). Low temperature dry distillation, direct liquefaction and indirect liquefaction of coal mainly produce liquid fuel, which was developed in the first half of the 20th century. After World War II, its products tended to stagnate because it could not compete with natural oil economically. At present, there are only indirect coal liquefaction plants in South Africa. Other direct chemical processing of coal, such as the production of montan wax, sulfonated coal, humic acid and activated carbon, still have small-scale applications. The coal produced by coal chemical industry in the world is mainly used as fuel for power stations and industrial boilers; Used in coal chemical industry accounts for a certain proportion, mainly coking and gasification coal. In 1980s, the annual output of coke and coal tar in the world was about 340Mt and 16Mt respectively (naphthalene extracted from it was about 1Mt). Coal tar processing products are widely used to make plastics, dyes, spices, pesticides, drugs, solvents, preservatives, adhesives, rubber and carbon products. 198 1 year, the total output of synthetic ammonia in the world is 95.3 million tons, mainly from oil and natural gas. Ammonia production from coal only accounts for about 10%; The proportion of methanol synthesized from coal is also very small, accounting for only about 1% of the total methanol production.