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Dimethyl ether - modern fuel for diesel engines

Ethers are derivatives of alcohols in whose molecules the hydrogen atom of the OH group is replaced by a carbon radical. Ethers are characterized by metamerism and isomerism of the hydrocarbon chain.

The isomerism of the hydrocarbon chain is due to its branching.

Metamerism is a kind of isomerism in which two or more ethers have a similar molecular formula, but a different molecular structure due to different radicals on either side of the oxygen bridge. For example, the molecular formula C4H10O corresponds to three esters:

- CH3-O-CH (CH3) 2;

- CH3-O-C3H7;

- C2H5-O-C2H5.

These substances are produced synthetically, including dimethyl ether. The formula for this compound is represented by two methyl radicals, which are linked together by an oxygen "bridge".

It should be noted that in nature, esters do not occur in the free state. Dimethyl and methylethyl esters are gases. The next few representatives are liquids, while the higher esters are solids. They are very poorly soluble in water, excellent in organic solvents. The average representatives (dipropyl, propyl ethyl, diethyl) are excellent organic solvents. The physical properties of these organic compounds vary with the molecular weight.

Dimethyl ether: preparation

The described substance is readily soluble in water, ethanol, diethyl and dipropyl ether. This ether is obtained due to the dehydration of methanol and as a by-product of the production of methanol from H2 and CO. Used in refrigerating plants as a coolant.

In the near future diesel engines will be transferred not to gas, but to dimethyl ether. Such a reconstruction of their cost is much cheaper in comparison with the transition to natural gas. The leading countries for the production of such engines are the United States, Russia and Japan.

At the beginning of the 21st century, the Russian government decided to use alternative types of fuel on motor vehicles. Dimethyl ether is used in trucks. This cardinal decision was made in connection with the fact that emissions of nitrogen compounds from diesel engines installed on trucks exceed the established standards by several times. Dimethyl ether is ideal for this type of engine, they hardly need to be reconstructed. Only through the use of a new alternative fuel, new upgraded engines have reached the level of ecological compatibility of Euro-3.

The governments of many countries of the world are confident that dimethyl ether will be the fuel of the future for diesel engines. To date, this substance is produced mainly by processing natural gas. At the first stages of the technological process, natural gas is reformed, resulting in synthesis gas. After that, it turns into methyl alcohol. The methanol is then allowed to dehydrate, whereby dimethyl ether is obtained. There is another method for the synthesis of this ether - direct conversion of synthesis gas to methanol.

Ethers in comparison with diesel fuel have their advantages and, of course, drawbacks. In the structure of the ether molecule there are no "carbon-carbon" bonds. Due to the significant oxygen content, a good atomization is provided when the ether is injected into a medium with a temperature above the boiling point of the substance itself. These characteristics improve the combustion of fuel. By using this alternative fuel , the engine noise level is reduced, while its reliability is increased.

The main disadvantages of this ether include lower heat of combustion and lower density. All this leads to an increase in fuel consumption. This substance has very poor lubricating properties.

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