RU2527546C2 - Wasteless method of obtaining polymethylene naphthalene sulphonates with regulated low content of sodium sulphate - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to a method of obtaining polymethylene naphthalene sulphonates (PNS) with a regulated low content of sodium sulphate, which includes sulphonation of a naphthalene-containing raw material with a sulphonating agent under conditions of the forced discharge of a steam-gas mixture of a balanced composition to a degree of action of sulphuric acid 1.5-4% counted per residual sulphuric acid, with the regulation of naphthalene and water content in the steam-gas mixture and a quantity of the discharged steam-gas mixture in total being carried out by a step-by-step creation of vacuum, and the first stage of sulphonation is carried out in a standard sulphurator apparatus in a temperature interval of 140-168°C and pressure in the apparatus of 0-20 kPa, and at the second stage in the same apparatus without interruption of the technological process, vacuum -15÷-90 kPa is created with an exposure at a temperature of 150-155°C, with further increase of temperature at the end of the process to 160-165°C and obtaining a sulphomass with the total titratable acidity of 22.5-26%.

EFFECT: elaborated is the method of obtaining PNS with the regulated low content of sodium sulphate, which can be applied as dispersants of powder-like materials of different nature, in particular as superplasticisers of concrete mixtures and mortars.

5 cl, 4 tbl

Description

The invention relates to the production of high molecular weight surfactants based on polymethylene naphthalenesulfonates (PNS) - polycondensation products of naphthalenesulfonic acids and formaldehyde, used, for example, as a superplasticizer of concrete and mortar mixtures or dispersants in various industries.

Sulfation of naphthalene is a reversible process [1], as a result of which the technical naphthalenesulfonic acid (sulfomass) used in further technological processes always contains residual sulfuric acid, and the final products obtained on its basis are an admixture of sulfates.

Most often, at the stage of neutralization, sodium hydroxide is used in the preparation of PNS; accordingly, the disadvantage of the products obtained is the tendency to form a crystalline precipitate when the temperature is lowered, since the solubility of sodium sulfate is characterized by a pronounced temperature dependence and is 16.3% at + 20 ° C, and only 4.8% at 0 ° C [2] .

A known method of reducing the residual sulfuric acid in the sulfomass by sulfonation with a large excess of naphthalene [1], however, the process of separating unreacted naphthalene from naphthalene sulfonic acid is very laborious and energy-intensive, and the sulfomass is contaminated with dinaphthyl sulfones - the products of the interaction of naphthalenesulfonic acids with free naphthalene.

The closest in technical essence, the content of impurities in the sulfomass and the composition of the resulting PNS is the following method [3].

A method of producing a superplasticizer includes sulfonation of naphthalene with concentrated sulfuric acid in a sulfator, blowing off unreacted naphthalene by feeding sharp water vapor into the apparatus and trapping the swollen naphthalene, polycondensation of sulfonation products with formaldehyde and neutralization of the reaction mass after polycondensation, while water is captured through naphthalene to trap it temperature 40-60 ° C. In this case, naphthalene desublimation occurs in the form of flakes, on which further capture of naphthalene occurs. The degree of capture is 90-98%.

This method does not provide a regulated low content of sodium sulfate. In addition, when direct steam is supplied, partial hydrolysis of the isomeric α-naphthalene sulfonic acid [1] formed as a co-product is observed, with a further increase in the sulfuric acid content in the reaction mass (respectively, sodium sulfate in the final product).

The aim of the present invention is a non-waste method for producing PNS with controlled low content of sodium sulfate, including sulfonation of naphthalene-containing raw materials with a sulfonating agent with removal of the resulting vapor-gas mixture, condensation of the resulting sulfomass with formaldehyde, dilution and subsequent neutralization of the reaction mass, while the sulfonation process is carried out under conditions of forced vapor-gas removal mixtures of a balanced composition to the degree of actuation of sulfuric acid 1.5-4% in terms of residual sulfuric acid.

The content of naphthalene and water in the vapor-gas mixture and the amount of steam-gas mixture discharged are generally regulated by stage-by-stage vacuum generation, the first stage of sulfonation being carried out in a standard sulfurizer in a temperature range of 140-168 ° C and a pressure in the apparatus of 0-20 kPa, and at the second stage in the same apparatus, without interrupting the process, create a vacuum of -15 ÷ -90 kPa and maintain at a temperature of 140-155 ° C, followed by a rise in temperature at the end of the process to 160-165 ° C and obtaining sulfomass with a total titratableislotnostyu 22,5-26%.

The duration of sulfonation with any method of conducting the process depends on the volume of technological equipment and can vary from 3 to 9 hours.

When implementing the proposed method, the content of sodium sulfate in the final products is in the range of 2-6% by weight of dry matter.

It is important that the proposed technology does not affect the molecular composition of the obtained products based on PNS, and they can be used as superplasticizers of concrete mixtures or dispersants.

When implementing the proposed method, coke-chemical technical naphthalene, petrochemical technical naphthalene, a naphthalene fraction with a crystallization temperature of at least 75 ° C, or a mixture of any number of these components are used as naphthalene-containing raw materials.

When implementing the proposed method, sulfuric acid with a basic substance content of more than 90%, including regenerated acid of any origin, is used as a sulfonating agent.

Between the totality of the essential features of the claimed invention and the achieved technical result, there is a causal relationship.

The data presented in Table 1 on the implementation of the proposed sulfonation method clearly demonstrate that by regulating the vacuum in the system (depth, time of creation and duration of action), it is possible to obtain sulfomasses of a given composition with a total acidity of 22 with a varying ratio of naphthalene-containing raw materials: a sulfonating agent 5-26.0% and a free sulfuric acid content of 1.5-4%.

When creating a vacuum in the system immediately after mixing the reagents, the discharged ASG is enriched with naphthalene, as a result, the resulting sulfomass contains an excess of free sulfuric acid (example 2).

If the vacuum created at the second stage is not deep enough, only naphthalene, but not water vapor, will be removed from the sulfomass from the discharged ASG. As a result, sulfomass will also be characterized by an increased content of free sulfuric acid (example 3).

When forced withdrawal of ASG balanced composition with a different initial ratio of naphthalene-containing raw materials: sulfonating agent obtained sulfomass with a low content of free sulfuric acid (examples 4-6).

The synthesized sulfomasses 4-6, as well as the prototype sulfomasses were used in the polycondensation reaction with formaldehyde, the reaction masses obtained under standard conditions (115-130 ° C, 2-3 hours) were neutralized with NaOH and the content in the finished product was determined by standard methods [4] sodium sulfate product (Table 2). If, using sulfomass according to the invention, products with a regulated low (1.5-6%) sodium sulfate content are immediately obtained, then in the case of prototype sulfomass, partial deposition of excess sulfate in the form of gypsum is necessary. The amount of by-products formed and possible PNS losses are shown in Table 3.

Evaluation of the effectiveness of products with a low content of sodium sulfate obtained by the proposed non-waste method and by partial deposition of sulfates in the form of gypsum as a superplasticizer of concrete mixtures was carried out in accordance with GOST 30459-2003 on a concrete mixture of the composition (kg / m ³ ): cement - 350 (Novorossiysk PC 600), sand - 850, crushed stone - 990, water - 185. The additive was dosed by dry matter in% of the mass of cement. Mobility was determined according to GOST 10181.1, strength - according to GOST 10180. The results obtained (Table 4) indicate a very close effectiveness of the products being compared, corresponding to the requirements of GOST 24211-2003. This result is logical, since the technical effectiveness of superplasticizers is determined by the molecular composition of PNS formed during the polycondensation of naphthalenesulfonic acid and formaldehyde [5].

Literature

1. N. Donaldson. Chemistry and technology of naphthalene compounds. Per. under the editorship of A.I. Koroleva, Moscow: Goskhimizdat, 1963, 656 p.

2. Brief chemical encyclopedia. - M.: “Soviet Encyclopedia”, 1964.

3. SU 1694518 A method of obtaining a plasticizer. Publ. November 30, 1991 Bull. Number 44

4. “Recommendations for physico-chemical control of the composition and quality of the superplasticizer S-3.- M .: NIIZhB. 1984. 54 p.

5. Vovk A.I. About the quality of naphthalene formaldehyde superplasticizers. Concrete technology. - 2008. No. 2. - S. 18-19, No. 3, - S. 8-9, No. 4, - S. 20-21.

Table 1 №№ The ratio of naphthalene: sulfur
acid First stage Second stage The composition of sulfomass,% t, ° C p, kPa Successor
hour t, ° C p, kPa Successor
hour total acids
nost free acids
nost one 1: 1.06 160-165 0-10 3 - - - 25,4 7.5 2 1: 1,03 160-165 -thirty 3 - - - 26.0 6.8 3 1: 1,03 160-165 0-10 2 155-160 -40 2 25.9 5.7 four 1: 1 - - - 150-165 -60 3 25.0 4.0 5 1: 1,03 160-165 5-15 2 150-165 -70 0.5 24.6 2.9 6 1: 0.9 160-165 5-15 1,5 150-165 -80 1,5 22.5 1,5

table 2 №№ The initial sulfomass according to table 1 The composition of the polycondensation product, wt.% PNS Na ₂ SO ₄ one No. 1, prototype 89.0 11.0 2 No. 4, on request 94.3 5.7 3 No. 5, by request 96.1 3.9 four No. 6, on request 98.0 2.0

Table 3 Polycondensation Product Na₂SO_four, wt.% The amount of gypsum from 1 t of 100% product Waste weight based on humidity Loss of PNS, kg (due to adsorption) prototype 4.0 84 210 9 prototype 2.0 115 290 eleven Number 3 3.9 - - - Number 4 2.0 - - -

Table 4 Additive Concrete Mix Characteristics Strength, MPa, aged, days cement, kg / m ³ W / C doses
ka,% draft of a cone, cm density, kg / m ³ air attraction,% one 7 28 prototype No. 1 of table 2 350 0.53 0.5 22 2405 3.2 20,2 39.0 43,4 by application No. 2 of table 2 350 0.53 0.5 22 2410 3.0 21.8 40,2 45.1 by application No. 3 of table 2 350 0.53 0.5 21 2405 3,1 21,4 39.5 44,2 by application No. 4 of table 2 350 0.53 0.5 21 2400 3.3 20.1 39.8 43.0

Claims (5)

1. A non-waste method for producing polymethylene naphthalene sulfonates with a controlled low content of sodium sulfate, including sulfonation of naphthalene-containing raw materials with a sulfonating agent with removal of the resulting vapor-gas mixture, condensation of the obtained sulfomass with formaldehyde, dilution and subsequent neutralization of the reaction mixture, characterized in that the forced sulfonation process is carried out under steam conditions mixtures of a balanced composition to the degree of actuation of sulfuric acid 1.5-4%, calculated on the remainder sulfuric acid, while the regulation of the content of naphthalene and water in the vapor-gas mixture and the amount of vented gas-vapor mixture as a whole is carried out by stage-by-stage creation of rarefaction, while the first stage of sulfonation is carried out in a standard sulfurizer in the temperature range 140-168 ° C and pressure in the apparatus 0-20 kPa, and at the second stage in the same apparatus, without interrupting the process, create a vacuum of -15 ÷ -90 kPa and maintain at a temperature of 150-155 ° C, followed by a rise in temperature at the end of the process to 160-165 ° C and receiving with Ulfomass with a total titratable acidity of 22.5-26%. 2. The method according to claim 1, characterized in that as a naphthalene-containing raw material, coke-chemical technical naphthalene, petrochemical technical naphthalene, a naphthalene fraction with a crystallization temperature of at least 75 ° C, or a mixture of any number of these components are used. 3. The method according to claim 1, characterized in that as a sulfonating agent, sulfuric acid is used with a basic substance content of more than 90%, including regenerated acid of any origin and technical acid. 4. The method according to claims 1 to 3, characterized in that the content of sodium sulfate in the final products is in the range of 2-6% by weight of dry matter. 5. The method according to any one of claims 1 to 4, characterized in that the obtained product based on PNS is used as a superplasticizer of concrete mixtures or a dispersant.