RU2265005C2 - Thermopolymerization inhibitor in processing of pyrolysis intermediate products and method for its preparing - Google Patents

Abstract

FIELD: coal and petroleum chemistry industry, chemical technology.

SUBSTANCE: invention relates to chemical technology in coal processing and to technology of polymers and monomers. The thermopolymerization inhibitor represents product of polycondensation reaction of extractive total coal-tar phenols comprising monoatomic phenols, diatomic phenols and coal-tar resin with formaldehyde by novolacs type in acid medium with viscosity value 60-75 s and comprising 0.1 percent of weight of free phenols, not, above, and this product is soluble in butyl alcohols. Method for preparing inhibitor involves the polycondensation reaction of extractive total coal-tar phenols with formaldehyde by novolacs type in acid medium in the following ratio of reagents, in weight parts: extractive total coal-tar phenols : formaldehyde : acid = (170-180):(36.3-38.1:(2.9-3,2), respectively, wherein the polycondensation reaction temperature is maintained about 80°C and distillation off of water and unreacted phenol from the reaction mixture is carried out at 100°C, and product is used in butyl alcohols before using.

EFFECT: improved preparing method of inhibitor.

3 cl, 1 dwg, 1 tbl, 3 ex

Description

The invention relates to the coal and petrochemical industries, to the chemical technology of coal processing, as well as the technology of polymers and monomers, in particular to the production of olefinic hydrocarbons, and can be used in plants such as EP, producing commercial ethylene and propylene, as well as aromatic hydrocarbons.

It is known that in the process of hydrocarbon pyrolysis a mixture of olefin hydrocarbons is formed, which, when further processed at elevated temperatures (130 ° C and above), polymerize and settle on the working surfaces of the equipment, leading to its clogging with polymer deposits [Mukhina TN, Barabanov N .L., Babash S.E. et al. Pyrolysis of hydrocarbons. M .: Chemistry, 1987, 240 pp.]. The most common inhibitors of unwanted polymerization of unsaturated components of liquid pyrolysis products (GIP) are phenolic compounds [Kurbatov VA, Liakumovich AG, Kirpichnikov PA // Petrochemicals. - 1983. - t.23, No. 1. - S.118-120], most often by-products of thermal processing of coal, the so-called coke chemical phenols.

It is known to use a mixture of total coke chemical phenols isolated from wastewater semi-coking of coal as inhibitors of the polymer formation process in the processing of ZHPP at a flow rate of 1.0-2.0 wt.%. [Berents A.D., Vol-Epstein A.V., Mukhina T.N. et al. Processing of liquid pyrolysis products. M .: Chemistry, 1985, p. 59-60].

Common features of the analogue and the present invention is the use of a thermopolymerization inhibitor in the processing of pyrolysis intermediates, which are based on phenols.

The disadvantage of this method is the relatively low inhibitory activity of total phenols, which requires to achieve the desired effect of inhibition of increased consumption of phenols. Their use in EP-type plants is associated with pollution of wastewater produced by phenols.

An increase in the inhibitory activity of coke chemical phenols is achieved by fractionation of extractive phenols, as a result of which part of the monohydric phenols is removed. The preparation obtained during this treatment is known under the brand name "ФЧ-16", which is a rather effective inhibitor of the thermopolymerization of diene hydrocarbons and pyrocondensates, at a flow rate of 0.01-2.00 wt.% [Ed. USSR No. 600133, C 07 C 7/18; 11/12; 7/04; C 08 F 2/42 ,. B. I., 1978, No. 12, p. 97].

A common feature of the analogue and the present invention is that in both cases a thermopolymerization inhibitor is used in the processing of phenol-based pyrolysis intermediates.

The disadvantages of this technical solution are the high consumption of the inhibitor, the relatively low inhibitory activity of the mixture of coke chemical phenols, as well as the high water solubility and the unpleasant specific smell of the inhibitor preparation, i.e. poor organoleptic properties.

The closest (prototype) in technical essence and the achieved effect to the proposed invention is described in US Pat. RF 2127750 (C 07 C 7/20; C 08 F 2/42, B.I., 1999, No. 8, p. 391) a technical solution to reduce polymer formation in the processing of pyrolysis intermediates, which is based on the introduction of an inhibitor, which is a fraction diatomic phenols (PCF). The latter is obtained from crude extractive phenols of semi-coking of coal by thermal and vacuum fractionation with separation of the fraction of monatomic phenols and coke resin. Before use, the inhibitor is dissolved in butanol and introduced in an amount of 0.01-0.02% by weight of the pyrolysis intermediates.

The analysis of the initial total extractive coke chemical phenols (SECF) showed that they contain 58-60 wt.% Monatomic phenols (of which ≈40% pure phenol), 28-32 wt.% Diatomic phenols (pyrocatechol, resorcinol and hydroquinones) and ≈10 wt.% Coke chemical resin (COP). The fraction of monatomic phenols practically does not have any noticeable inhibitory activity, as well as the coke resin. When fractionating SECF after distillation of monohydric phenols, the so-called fraction of residual phenols (FOF) remains, which is a mixture of diatomic phenols (PCF) and CS. The separation of the PCF from the COP is carried out under vacuum. This is the most energy-intensive stage of phenol fractionation.

The disadvantages of the prototype are the high energy consumption for the allocation of the specified fractions (PCF), as well as the good solubility in water of the phenols contained in it, which does not exclude the possibility of the latter entering sewage from the production of electric power. The presence of an unpleasant specific smell of this phenol fraction should also be attributed to disadvantages, as significantly complicates the work with her.

The technical task of the invention is:

- Obtaining an effective thermopolymerization inhibitor well soluble in the processed product during the processing of pyrolysis intermediates;

- Elimination of the disadvantages characteristic of traditionally used phenolic inhibitors, namely the reduction of their water solubility and the removal of an unpleasant specific smell;

- Expanding the range of inhibitors by obtaining them using a low-cost (non-energy-intensive) technology that allows the efficient and rational use of extractive (total) coke chemical phenols without first removing monohydric phenols and resins from them.

The technical result, which consists in eliminating these drawbacks of known inhibitors based on extractive (total) cokehomic phenols, is achieved by using a polycondensation product of these phenols with novolac type formaldehyde polycondensation in the processing of pyrolysis intermediates in the presence of an acid catalyst (for example, oxalic acid , hydrochloric acid, n-toluenesulfonic acid, phosphoric acid) having a viscosity of 60-75 sec and containing not more than 0.1 wt.% free x phenols. The product is dissolved in butyl alcohols and in the form of a butanol solution [commodity form] is used in an amount of 0.035-0.040% based on the weight of the pyrolysis intermediates. The inhibitor does not have a specific unpleasant odor, it is soluble in butyl alcohols and in pyrolysis intermediates and insoluble in water.

The technical result, which consists in eliminating these shortcomings in the method for producing phenol-based inhibitors, is achieved by carrying out a phenol-formaldehyde polycondensation reaction of the novolac type in an acidic medium with the following ratio of reactants in weight fractions: extractive (total) coke phenols: formaldehyde: acid (for example , oxalic acid, hydrochloric acid, n-toluenesulfonic acid, phosphoric acid) 170-180: 36.3-38.1: 2.9-3.2. The synthesis of the inhibitor is carried out under mild conditions, because the polycondensation temperature is maintained at about 80 ° C, and the distillation of water and unreacted phenol from the reaction mixture is carried out under vacuum at a residual pressure of 0.12 at at 100 ° C.

A comparative analysis of the prototype and the present invention allows us to conclude that the claimed thermopolymerization inhibitor of the pyrolysis intermediates is another phenolic compound, namely the product of phenol-formaldehyde condensation during acid catalysis, i.e. phenolic oligomer obtained by novolac type. The product is well compatible with hydrocarbon streams, does not dissolve in water, has a viscosity of 60-75 sec and contains no more than 0.1 wt.% Free phenols. The synthesis of the inhibitor is carried out under mild conditions with the following ratio of reactants in weight fractions: extractive (total) coke chemical phenols: formaldehyde: acid 170-180: 36.3-38.1: 2.9-3.2.

The implementation of the proposed invention is shown in the following examples.

The fraction of the original extractive total coke chemical phenols used for the preparation of the inventive inhibitor contains the same components as the prototype fraction. The component composition of the fraction is presented in the following table.

Table
The composition of the extractive total coke chemical phenols Monoatomic phenols, wt.% 60.50 including phenol 13.30 2-ethyl-4-methylphenol 0.16 2-methylphenol 10.14 4-ethyl-3-methylphenol 0.69 4-methylphenol 13.32 3-ethyl-5-methylphenol 0.20 2,6-dimethylphenol 4.34 2,3,5-trimethylphenol 0.27 2-ethylphenol 1.03 4-propylphenol 0.15 2,4-dimethylphenol 10.40 2-methyl-5- (1-methylethyl) phenol 0.32 4-ethylphenol 3.74 2,3,6-trimethylphenol 0.10 3,5-dimethylphenol 0.75 4- (1-methylpropyl) phenol 0.10 2,4,6-trimethylphenol 0.42 2-butylphenol 0.13 2-propylphenol 0.15 4-ethyl-2-methoxyphenol 0.09 2-ethyl-6-methylphenol 0.66 2-naphthol 0.04 Diatomic phenols, wt.% 30.09 including Catechol 7.35 5-methylresorcinol 0,07 3-methylpyrocatechol 9.67 4-ethylresorcinol 2.21 4-methylpyrocatechol 4.96 4,5-dimethyl resorcinol 0.29 Resorcinol 1,69 methylhydroquinone 0.17 2-methylresorcinol 1.51 2,3-dimethylhydroquinone 2.17 Coke resin 9.41

Example 1. Obtaining an inhibitor of thermopolymerization of pyrolysis intermediates using oxalic acid as a catalyst

The synthesis of phenol-formaldehyde oligomer novolac type is carried out according to the following procedure:

170-180 g of extractive coke oven phenols and 150 cm ^{3 of} water are placed in a 3-necked flask with a capacity of 1000 cm ³ , 95-105 cm ³ of oxalic acid solution (4.3 g (COOH) ₂ × 2H ₂ O in 100 are added to the resulting solution cm ^{3 of} water). The reaction mixture was stirred for 20 minutes, after which the flask was heated in a water bath to 80 ° C for 0.5 hours. Upon reaching a temperature of the reaction mixture of 80 ° C, 98-103 cm of a formalin solution (37% formaldehyde solution) are uniformly applied over two hours. After the addition of formaldehyde is completed, the mixture is kept for some time to achieve a viscosity of 60-75 seconds according to VZ-4, after which water is distilled off. The device is connected to a vacuum system (p _ocm = 0.12 am), at the temperature of a boiling water bath, the remaining water and unreacted phenol are distilled off. A dark brown gummy substance is obtained with a yield of 91-95% by weight.

The controlled parameters for the synthesis of phenol-formaldehyde novolac resin based on coke chemical phenols are the solubility of the obtained product in butyl alcohols (it should be 100%) and the content of free phenol (it should not exceed 0.1 wt.%). Therefore, it is necessary to strictly adhere to the process parameters: condensation temperature, reagent ratios and viscosity of the resulting inhibitor (phenol formaldehyde oligomer).

Example 2. Obtaining an inhibitor of thermopolymerization of pyrolysis intermediates using hydrochloric acid as a catalyst

The synthesis of the novolac type phenoformaldehyde oligomer is carried out as in Example 1, with the difference that a 5% hydrochloric acid solution is used as the acid catalyst.

A dark brown gummy substance is obtained with a yield of 91-95% by weight.

The controlled parameters of the synthesis of phenol-formaldehyde novolac resin based on coke chemical phenols are also the solubility of the obtained product in butyl alcohols (it should be 100%) and the content of free phenol (it should not exceed 0.1 wt.%). Therefore, it is necessary to strictly adhere to the process parameters: temperature, ratio of reagents and viscosity of the obtained inhibitor (phenoformaldehyde oligomer).

Example 3. Inhibition of thermopolymerization of pyrocondensate

The product obtained by the above-described method is cooled, dissolved in the required concentration (about 50 wt.%) In butyl alcohols and used as an inhibitor of thermopolymerization of pyrolysis intermediates in the amount of 0.035-0.040% by weight of the processed pyrocondensates taken from the cube of K-27 column manufactured by EP- 300. The composition of pyrocondensates in addition to solvents - benzene, toluene (65-70 wt.%) Includes cyclic olefin and diene compounds, as well as styrene, its homologues and derivatives. The total content of unsaturated products in pyrocondensates varies greatly and amounts to 17-25 wt.%.

The effectiveness of the proposed inhibitor tested in laboratory conditions and is illustrated by the following experiments. For comparison and as a control, pyrocondensate was treated with total coke chemical phenols (SF), residual phenols fraction (FOF). The pyrocondensates were treated at a temperature of 130 ± 1 ° С for 1 hour, after which, according to the standard method GOST 25336-82 on a POS-77 device, the content of total resins was determined in it by stripping with water vapor at 160 ° С. The results of the analytical control of the inhibition of thermopolymerization of pyrocondensates are presented in the drawing.

As can be seen from the drawing, during thermal processing of pyrocondensates, the proposed inhibitor (MF) exhibits high inhibitory properties, and its inhibitory ability is most effective at an inhibitor cost of 0.035-0.040% by weight of the processed pyrocondensate. The inhibitory activity of total coke chemical phenols (SF) is directly proportional to their amount added to the pyrocondensate. The curves of the efficiency of inhibition of the thermopolymerization of pyrocondensate during its treatment with MF and FOP are similar and have a parabolic shape.

In comparison with SF, these inhibitors at a lower consumption have a stronger inhibitory effect. It should be noted that with the similar inhibitory properties of MF and FOF, the proposed inhibitor (MF) compares favorably with the known one in that it does not have a sharp unpleasant specific odor characteristic of coke chemical phenols and that this drug does not dissolve in water . The latter is confirmed by experiments on the re-extraction of the phenolic inhibitor from pyrocondensate into the aqueous phase. It was shown that water washing out phenols from the organic phase does not occur. This property of the proposed inhibitor makes it possible to use it in large quantities of the inhibitor to achieve the greatest inhibition effect without fear of phenols entering the aqueous phase and production wastewater.

Thus, it is shown that the proposed inhibitor exhibits a high inhibitory ability in the thermal processing of pyrolysis intermediates, is well compatible with processed hydrocarbons, does not dissolve in water, the effectiveness of which is quite comparable with the inhibition performance of known phenolic inhibitors (PCh-16, PCF) with the same expenses. Unlike the prototype, this phenolic preparation is synthesized under mild conditions by implementing a simple process of phenol-formaldehyde polycondensation, due to which the task of reducing energy consumption when it is received is solved. In addition, the modification of the total (extractive) coke-chemical phenols by phenol-formaldehyde condensation of the novolac type makes it possible to rationally utilize them.

The use of MF in the processing of pyrocondensates effectively inhibits the undesirable process of the formation of thermopolymers, which allows to increase the overhaul mileage of distillation columns, boilers and heat exchangers of EP type production. The latter for production, for example, EP-300 can bring significant economic effect, because its simple for only one day carries a loss of not less than 9 million rubles. at current prices. In addition, the possibility of contamination of industrial wastewater with phenols is also excluded.

The proposed thermopolymerization inhibitor differs from the known ones by good organoleptic properties, good compatibility with pyrolysis intermediates, insolubility in water, and the method for its preparation is simplicity, manufacturability and undoubted economy.

Claims (3)

1. Thermopolymerization inhibitor in the processing of pyrolysis intermediates based on extractive total coke chemical phenols, characterized in that it is a polycondensation product of extractive total coke chemical phenols, including monohydric phenols, diatomic phenols and novolac type formaldehyde coke resin with an acid viscosity of 60, -75 s, containing not more than 0.1 wt.% Free phenols and soluble in butyl alcohols. 2. The method of producing an inhibitor according to claim 1, characterized in that the method includes a polycondensation reaction of extractive total coke chemical phenols containing monohydric phenols, diatomic phenols and a coke chemical resin with novolac type formaldehyde in an acidic medium, in the following ratio of reactants, in weight fractions: extractive total coke chemical phenols: formaldehyde: acid = 170-180: 36.3-38.1: 2.9-3.2, the polycondensation temperature is maintained at about 80 ° C, and distillation of water and unreacted phenol from the reaction mixture is carried out they melt at a temperature of 100 ° C, the product is dissolved in butyl alcohols before use. 3. The method according to claim 2, characterized in that the distillation of water and unreacted phenol from the reaction mixture is carried out under vacuum at a residual pressure of 0.12 atm.