The boundaries of the chemical industry are somewhat confusing

The petroleum industry is generally considered to be independent of the chemical industry because in the early 19th century, crude oil was simply distilled. However, the production process of modern petroleum industry will bring chemical changes. By any definition, some products of modern refineries are chemicals. The term Petrochemical is used to describe these chemical operations. However, because these operations are often carried out in the same plant as primary distillation, it is difficult to maintain the difference between petroleum industry and chemical industry.

In a sense, metals are chemicals because they are produced chemically. Before the ore is refined, sometimes it needs to be processed by chemical methods; the refining process also involves chemical reactions. Metals such as steel, lead, copper and zinc are produced in fairly pure form and later processed into useful shapes. However, the steel industry, for example, is not considered part of the chemical industry. In modern metallurgy, titanium, tantalum and tungsten are produced by a large number of chemical processes, but they are still classified as primary metals.

So the boundaries of the chemical industry are somewhat confusing. Its main raw materials are fossil fuels (coal, natural gas and petroleum), air, water, salt, limestone, sulfur or the like, as well as some special raw materials for special products, such as phosphate and mineral fluorspar. The chemical industry transforms these raw materials into first, second and third products, which are distinguished according to the distance between the products and the consumers. The first product refers to the place farthest away from the consumers. These products are usually only the final products of the chemical industry itself; a major feature of the chemical industry is that its products almost always need further processing before reaching the final consumers.

So, paradoxically, the chemical industry is its own best customer. Before a common chemical product enters the market from the chemical industry, it has to pass from one factory to another several times.

The same product has many ways, the same product has many uses. Ethylene glycol, for example, is most used as an antifreeze for cars, but it is also used as a hydraulic brake fluid. Further processing will produce many derivatives, which are used as additives in textile, pharmaceutical and cosmetic industries; as emulsifiers in pesticides and fungicides; as demulsifiers for petroleum. Basic chemicals, such as chlorine or sulfuric acid, are used so much that they cannot be listed one by one.

Due to the competition within the chemical industry and between chemicals, the chemical industry invests a lot of money in research, especially in highly industrialized countries. The proportion of research revenue varies from sector to sector; companies that specialize in mass production of products that have been widely used for many years spend less, while competition in new areas can only be met through intensive research efforts.