RU2104921C1 - Method for dissolution of elementary sulfur - Google Patents

Abstract

FIELD: chemical technology. SUBSTANCE: system comprising hydrazine hydrate and amine at their molar ratio 1:0.05-0.5 is proposed for dissolution of elementary sulfur. Maximal dissolution of sulfur (its value being 1344 g/l) takes place in the presence of primary amines, molar ratio of hydrazine hydrate and amine being 1:0.5. EFFECT: novel effective solvents for sulfur are proposed. 1 tbl

Description

 The invention relates to the production and use of elemental sulfur, namely the development of new effective solvents for elemental sulfur.

As solvents for elemental sulfur, tri- and tetrachlorethylene, as well as some oil products, are used: AR-1, ethylbenzene fraction (EBP), and pyrolysis resin - PS. The disadvantages of these solvents are their low efficiency and high dissolution temperatures (above 80 ^o C).

 A known method for the rapid dissolution of elemental sulfur in tanks and pipelines by treatment with dialkyl disulfides containing 5-10 parts of an aliphatic mono-, di- or triamine (US Patent No. 4239630, 1980) and [1].

 The disadvantage of this method is the use of expensive disulfides. Their use is also limited due to unpleasant odors and the inability to regenerate sulfur from such solutions.

There is a method of dissolving sulfur in aqueous solutions of NaOH with the formation of Na ₂ S _n [2]. The highest solubility of sulfur is achieved at 80-90 ^o C and a high concentration of NaOH (30-60%).

 The disadvantage of this method is the high temperature of dissolution, a significant consumption of sulfur on the side reactions of its oxidation and losses associated with this, a high consumption of alkali and the corrosive effect of the resulting solutions.

 The purpose of the invention is to increase the efficiency of the process of dissolution of sulfur and the exclusion of the corrosive effect of sulfur solutions.

 This goal is achieved in that a new hydrazine hydrate-amine system is used as a solvent for elemental sulfur. As the amine used triethylamine, triethanolamine, morpholine and monoethanolamine.

The dissolution of elemental sulfur in the hydrazine hydrate-amine system proceeds exothermally - the reaction mass is heated to 60-65 ^o C. The amount of dissolved sulfur depends on the nature of the amine used and its concentration in the hydrazine hydrate solution (table). In 1 l of hydrazine hydrate in the presence of amines, 700-1344 g of sulfur is dissolved. Primary amines, monoethanolamine, exhibit the highest dissolution effect. An increase in the molar fraction of the amine in the hydrazine hydrate solution from 5 to 50% leads to an increase in the amount of dissolved sulfur in the system by about 1.5 times.

 As a result of the dissolution of sulfur in the hydrazine hydrate-amine system, dark red solutions are formed which are stable during storage under ordinary conditions. When diluted with water, the resulting solutions quickly eliminate sulfur, which is released by filtering aqueous suspensions.

 Hydrazine hydrate dissolves sulfur without the addition of amines, however, a significant amount of it is spent on the formation of hydrogen sulfide, which promotes the decomposition of hydrazine to ammonia.

 The proposed method for dissolving elemental sulfur has the following advantages.

 1. Lack of alkali in the solvent system.

 2. The solvent hydrazine hydrate-amine system does not cause corrosion of metal surfaces.

 3. Higher efficiency of the dissolution process: at low amine concentrations, more sulfur is dissolved in the hydrazine hydrate-amine system than in the hydrazine hydrate-alkali system.

 4. High dissolution rate under mild conditions.

 5. The simplicity and technological process in industrial use.

 6. Obtaining storage stable sulfur solutions that are suitable for use in industrial organic synthesis and in various industries, for example, in the pulp and paper industry.

 The method is illustrated by the following examples.

 Examples 1-10 (the results are shown in the table).

Sulfur is dissolved in an experimental setup consisting of a four-necked flask equipped with a stirrer, reflux condenser, thermometer and sulfur inlet. In a flask, a solution of an amine in 50 ml of hydrazine hydrate is prepared (concentrations are shown in the table), and with stirring, sulfur is introduced in portions as it is dissolved to obtain a saturated solution. In the process of dissolution of sulfur, the temperature of the solution rises to 60-65 ^o C. The dissolution is completed after 1 h. When cooled, the dark red sulfur solutions remain homogeneous and are stored for a long time without decomposition. The table shows the conditions and results of the dissolution of sulfur in the developed new systems.

 Example 11 (for comparison).

 Similarly, sulfur is dissolved in pure hydrazine hydrate in the absence of an amine. 32 g of sulfur are dissolved in 50 ml of hydrazine hydrate, which in terms of 1 liter is 640 g or 20 mol / l, i.e. less than in the presence of an amine (see table).

 When diluted with water, sulfur solutions are destroyed, and most of the sulfur precipitates.

Claims (1)

 A method for dissolving elemental sulfur by treating it with a solvent, characterized in that a mixture of hydrazine hydrate with amine taken in a molar ratio of 1 0.05 0.5, respectively, is used as the solvent.

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