SU1657473A1 - Method of producing thermally expanded graphite - Google Patents

Abstract

The invention relates to carbon-graphite materials technology, in particular, a method for producing thermally expanded graphite, which is a promising material for composites, as well as heterogeneous catalysts, with the aim of eliminating wash water and reducing the amount of harmful waste gases. The proposed method involves treating graphite with an excess mixture. concentrated sulfuric and nitric acids, separating the formed compound of the introduction of graphite from an excess of acids, treatment with gaseous ammonia formed Graphite embedding compounds to saturation and subsequent heat treatment for expansion in plasma of an inert gas with an average mass temperature of 1000-2000 ° C

Description

The invention relates to the chemistry of carbon-graphite materials, specifically to a method for producing thermally expanded graphite, which is a promising material for the creation of carbon-carbon composites, as well as heterogeneous catalysts and sorbents.

The aim of the invention is to eliminate wash water and reduce the amount of harmful waste gases.

Example 1. A reactor with a stirrer was charged with 100 g of natural graphite, 600 g of sulfuric acid (concentration 92% by weight) and 40 g of nitric acid (concentration 55% by weight), stirred for 60 minutes, the excess acid was separated, the resulting compound of graphite was treated with gaseous ammonia until the absorption of ammonia is stopped. The resulting free-flowing product is heat treated.

for expansion using nitrogen as a heat carrier plasma with an average mass temperature in the reactor of 1500 ° C. Thermally expanded graphite (TRG) is obtained with an apparent density of 4.6 g / l.

Excess acids are removed without dilution, which makes it possible to reuse them in the process

EXAMPLE 2 In Example 1, but thermal expansion is carried out using nitrogen as a heat carrier with a mass-average temperature in the reactor of 1000 ° C. TRG with apparent density of 10.3 g / l is obtained.

Example 3, but thermal expansion is carried out using nitrogen as a heat carrier with a mass-average temperature in the reactor of 2000 ° C. TRG is obtained with an apparent density of 3 to 4 g / l

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PRI me R 4. In Example 1, but the heat treatment is carried out using argon plasma as a heat carrier with a mass-average temperature in the reactor of 1500 ° C. Gets a TRG with an apparent density of 4.8 g / l.

EXAMPLE 5 As in example 1, but thermal expansion is carried out using gels with a mass-average temperature in the reactor of 1500 ° C as the heat transfer plasma. TRG is obtained with an apparent density of 4.3 g / l.

Example 6. 100 g of natural graphite and 640 g of the mixture of acids from example 1 are loaded into a stirred reactor, the mixture is stirred for 60 minutes, the excess of acids is separated, the compound of the graphite is treated with ammonia until the absorption of ammonia is stopped. The resulting bulk product is thermally expanded using nitrogen as a heat carrier plasma with a mass-average temperature in the reactor of 1500 ° C. TRG is obtained with an apparent density of 4.7 g / l.

Example 7. As in Example 1. But thermal expansion is carried out using nitrogen as the heat carrier plasma with a mass-average temperature in the reactor of 1100 ° C, and liberated SOz is captured in the exhaust gases. The amount of released SO2 is 0.75 g / 0.26 L under normal conditions. TRG is obtained with an apparent density of 6.9 g / l.

Example 8. As in Example 1, but thermal expansion is carried out in a tubular electric furnace in a stream of nitrogen at 1100 ° C, and emitted SO2 is captured in the exhaust gases. The amount of released SOa is 2.3 g / 0.8 l under normal conditions. TRG is obtained with an apparent density of 7.3 g / l.

Example 9. 50 g of artificial graphite of the GTM brand, 300 g of sulfuric acid (concentration 92% wt.) And 20 g of nitric acid (concentration 55 wt.%) Are loaded into a stirred reactor, stirred for 60 minutes, the excess acid separated, the resulting compound the introduction of graphite is treated with ammonia gas to

saturation. The resulting bulk product is thermally expanded using nitrogen as a heat carrier plasma with a mass-average temperature in the reactor at 1500 ° C. TRG is obtained with an apparent density of 5.1 g / l.

PRI me R 10. In example 9, but using pyrolytic powdered graphite. TRG is obtained with an apparent density of 4.9 g / l.

Thus, the proposed method for the production of thermally split graphite makes it possible to eliminate washing water and reduce it by a factor of three compared with

in a known manner, (the amount of SO2 liberated is 9.17 g) 3.58 under normal conditions, the content of sulfuric anhydride in the exhaust gases, due to the fact that the processing of the graphite intercalation compound (acid

graphite) with gaseous ammonia and carrying out thermal splitting of inert gas in plasma reduces the oxidation of graphite with sulfuric acid and the formation of harmful waste gases, since the neutralization of graphite bisulfate with ammonia leads to the formation of ammonium sulfate, and, as is known, unlike sulfuric acid itself salts begin to interact with carbon with a noticeable

speeds at much higher temperatures of 100 and 600-800 ° C, respectively.

Claims (1)

Claims method for producing thermally expanded graphite, comprising treating graphite with an excess of a mixture of concentrated sulfuric and nitric acids, separating the resulting graphite embedding compound from an excess of acids, treating with ammonia, and subsequent heat treatment for expansion, characterized in that, in order to eliminate washing water and reduce the amount of harmful exhaust gas, ammonia gas treatment 5, the graphite embedding compound is subjected to saturation and heat treatment is carried out in an inert gas plasma with a mass-average temperature of 1000-2000 ° C.