SU148050A1 - The method of regeneration of used silica alloys - Google Patents

Description

A silicon-copper alloy is used as a contact mass in the preparation of organosilicon monomers.

The silica-copper alloy worked out during the direct synthesis of methylchlorosilanes can be used to directly synthesize phenylchlorosilanes, after which the used contact mass is discarded.

Since the production of phenylchlorosilanes is significantly less than the production of alkylchlorosilanes, most of the waste contact mass is not used, resulting in the loss of large amounts of copper.

The proposed method for the regeneration of the contact mass makes it possible to reuse the silica – silicon alloy for the direct synthesis of methylchlorosilanes and thus save expensive copper.

To regenerate the contact mass, silicon is added to the spent alloy and the mixture is impregnated with an 8% aqueous solution of zinc chloride, after which the heat treatment of the mass is carried out with air at 200 °.

The resulting regenerated contact mass has the same properties as fresh.

During regeneration, for example, 100 g of KP-1 grade silicon is added to 100 g of the spent alloy and mixed in an evaporation cup with 100 liters of an 8% ZnCb solution (grade "analytical or technical"). The resulting mixture is evaporated at 90 ° for 3 hours in a drying cabinet, periodically stirring it, and then incubated for 10-12 hours in air at a temperature of 200 °. During the heat treatment, the contact mass is self-heating, accompanied by its decarburization.

In the regenerated contact mass, radiographically detected: silicon, intermetallic compounds Sysc), copper, oxides of copper (Cu2O, CuO). Comparative data on the composition of the alloy are given in Table 1.

To check the activity, the regenerated contact was loaded into a vertical stainless steel reactor (mm).

Previously dry nitrogen was passed through the reactor and the required temperature was established. The synthesis of methylchlorosilanes was carried out in a suspended layer of 400 ° C and methyl chloride was passed through the reactor at a rate of 8 hedgehog / s. The mixture leaving the reactor was stepwise condensed and the individual products were condensed from the condensate by the rectification method. The composition of the condensate was checked by the chromatographic method. Table 1

In tab. 2 summarizes the results of the synthesis of methyl chlorosilanes on a regenerated silica-copper alloy. Synthesis was carried out at 400 ° for 5 hours.

The table shows that the synthesis of methylchlorosilanes on the silica-copper contact mass regenerated by the proposed method proceeds intensively with the formation of dimethyldichlorosilanes as the main reaction product (76%). With repeated mass regeneration, no decrease in the yield of dimethyldichlorosilanes is observed.

table 2

Subject invention

The method of regeneration of spent silica-alloys, characterized in that, in order to use the production wastes, silicon is added to the spent alloy, followed by impregnation with an 8% zinc chloride solution and heat treatment with air at 200 °.

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