Obtaining alcohols: methods and raw materials

2024 Author: Howard Calhoun | [email protected]. Last modified: 2023-12-17 10:16

Alcohols are used in so many industries and fields of activity. They produce various synthetic polymers, plasticizers, rubbers, detergents and many other types of products. The production of 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 process. Also one of the most important methods is the production of alcohols by hydration of olefins. This is how isopropyl, tert- and sec-butyl and ethyl alcohols are obtained. The production of methyl alcohol (methanol) is based on the 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: production of glycerol and ethanol.

Ethyl alcohol (ethanol) is one of the most mass-produced products. On its basis, a method for the manufacture of synthetic rubber was developed. Ethanol is obtained from wood hydrolysis products, ethylene, sulfite liquors and by the enzymatic method from food raw materials.

Producing 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 hydrocarbon feedstock, for example, using ethylene hydration. To get one ton of ethanol in an enzymatic way, 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 for the production of ethyl alcohol from various raw materials: from grain - 160, from potatoes - 280, from ethylene - 10. Obtaining alcohols from petrochemical raw materials is less costly and laborious.

Also a very important chemical product is methanol. Modern production of methyl alcohol is carried out by organic synthesis based on 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 outdated andreplaced by various low-pressure synthesis methods.

- Synthesis on copper-zinc-aluminum catalysts at low pressure. The use of low pressure synthesis methods can significantly reduce energy costs for 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 a suspension of an inert liquid and a fine catalyst. This is a method that allows you to increase the yield of the product, while reducing energy costs. Methods for obtaining alcohols are being improved. The three-phase system is an advanced production technology.