Alcohols are used in so many industries and fields of activity. They produce various synthetic polymers, plasticizers, rubbers, detergents and many other varieties of products. Obtaining alcohols is carried out using biochemical and chemical methods. Many of them are mass products of petrochemical synthesis. Chemical synthesis from hydrocarbons is a relatively inexpensive manufacturing method. Also one of the most important methods is the production of alcohols by hydration of olefins. Thus, isopropyl, tert- and sec-butyl and ethyl alcohols are obtained. Obtaining methyl alcohol (methanol) is based on dry distillation of wood.
The main processes by which alcohols are obtained:
- Alkaline hydrolysis of halogen derivatives: production of glycerol, benzyl alcohol and others.
- Hydration of epoxides and alkenes: ethylene glycol, ethanol, etc.
- Hydroformylation: hexanol, methanol, etc.
- Oxidation methods: production of higher fatty alcohols.
- Recovery methods: higher fatty alcohols, xylitol, etc.
- Biochemical methods: the production of glycerol and ethanol.
One of the most mass-produced products is ethyl alcohol (ethanol). Based on it, a method for manufacturing synthetic rubber was developed. Ethanol is obtained from the hydrolysis products of wood, ethylene, sulfite liquors and by the enzymatic method from food raw materials.
Obtaining alcohols (ethanol and methanol) from food raw materials and wood is an expensive and time-consuming process. Ethyl alcohol is much more profitable and easier to produce from inexpensive hydrocarbons, for example, by hydration of ethylene. To obtain one ton of ethanol in an enzymatic manner, it is necessary to process four tons of grain or eight tons of sawdust. For comparison: one ton of ethanol is obtained from 2.5 tons of petroleum distillates or ethylene gas. Labor costs in man-hours in the production of ethyl alcohol from various raw materials: from grain - 160, from potato - 280, from ethylene - 10. Obtaining alcohols from petrochemical raw materials is less costly and time-consuming.
Also a very important chemical product is methanol. The modern production of methyl alcohol is carried out by organic synthesis on the basis of carbon monoxide (II) or synthesis gas on an industrial scale. Technological schemes are different. Conventionally, they can be divided into the following three groups.
- Synthesis on zinc-chromium catalysts at high pressure. This process is obsolete and is replaced by various methods of synthesis at low pressure.
- Synthesis on copper-zinc-aluminum catalysts at low pressure. The use of synthesis methods at low pressure can significantly reduce the energy costs of production. With this production method, a high degree of purification of raw materials from impurities that adversely affect the catalyst is required.
- Synthesis of methanol in a three-phase system, which is carried out in suspension from an inert liquid and a finely divided catalyst. This is a method that allows you to increase product yield, while reducing energy costs. Methods for producing alcohols are being improved. The three-phase system is an advanced production technology.