SU361675A1 - Electrolytic carbon production method - Google Patents

Description

one

The invention relates to the production of carbon by the electrolysis of molten salts and can be used to obtain pure amorphous carbon, when ™

. .

variable at the creation of nuclear reactors

A known electrolytic method for producing carbon by cathode reduction of carbon from its compounds during the electrolysis of molten salt electrolyte containing carbonates of alkali or alkaline earth metals.

However, with the known method, a pear-shaped, firmly cemented precipitate is formed on the catholeum, which, in addition to carbon, contains oxides and metal oxides. After removing such a precipitate from the electrolyzer, the precipitate must be mechanically crushed and leached in hydrochloric acid solution.

 In order to obtain amorphous carbon free from impurities, electrolysis is carried out under a pressure of carbonaceous gas of more than 2 MPa, at a temperature not higher.

The excess pressure of carbon dioxide above the surface of the melt provides the necessary rate of supply of carbon dioxide to the cathode for direct electroreduction to carbon:

with + 0so,

. + 4e

and to neutralize oxygen gases:

2-

2с

If a non-carbonate electrolyte is used, then to maintain the constancy of the electrolyte composition during the electrolysis process, alkali metal carbonates are added.

in quantities of less than 5. Provide it. -J

The following anodic process at the first moment of electrolysis:

22CO + O +46

2CO

Thus, electrolytic decomposition of carbon dioxide into carbon and oxygen will be carried out in the process of electrolysis.

The lower temperature limit for the process is determined by the melting point of the electrolyte. The upper should not exceed 7OO C, since at higher temperatures carbon monoxide is formed.

The interval of applied current densities is 0,, 0 a / cm. The electrolysis of the proposed method can be carried out in sealed stainless steel electrolysis cells, within which the molten electrolyte is contained in graphite or corundum containers. Ka. Tungsten, nickel, graphite. Graphite anodes.

The advantage of the proposed method is that pure amorphous carbon, obtained by electrolysis directly from carbon dioxide, is a compact, but mechanically fragile sediment consisting of pure carbon easily separated from the cathode material.

Example. Lead electrolysis. melt K GOg-f 500 C,

3 atn.

carbon dioxide pressure PQQ

2

1 (..0.2 a / cm. At the cathode receive a to

pure amorphous carbon with an output of around 1OO%. The gas above the electrolyte enriches with oxygen. The composition of the electrolyte remains personalized.,

Pr and me r p. Conduct electrolysis of KF-LIF + 5% K CO2 at bOOS, carbon dioxide pressure P,., 8 MPa. On

2

Pure amorphous carbon is obtained in the cathode with a yield of lOO%. The electrolyte composition remains unchanged.

REFERENCE OF THE INVENTION

A method for electrolytically producing carbon by cathode reduction of carbon from its compounds during the electrolysis of molten salt electrolyte containing alkali or alkaline earth metal carbonates, characterized in that, in order to obtain amorphous carbon free from impurities, electrolysis is carried out

carbon dioxide more than 2 MPa, at a temperature not higher than 70 ° C.