The method of producing pentaerythritol
(57) Abstract:Use: in organic chemistry, upon receipt polyhydric alcohols, in particular pentaerythritol used in the manufacture of varnishes. The inventive product-pentaerythritol, wt. fraction of moisture and volatile 0,07 - 0,08. The pentaerythritol dried at 45 - 55oWith up to moisture content and volatile products from 1.0 to 1.5%, crush the lumps to particle sizes of 1 to 2 mm and heat-treated for 3 to 5 with the heat carrier heated to 160 - 180oWith and moving with a speed of 20 - 30 m/s 1 table. The invention relates to the technology of polyols, in particular pentaerythritol used in paint and other industries.A known method of producing pentaerythritol by the interaction of formaldehyde with acetaldehyde in the presence of calcium hydroxide. The resulting reaction mass, which contains dissolved pentaerythritol and calcium formate, is treated with soda ash deposition precipitation of calcium carbonate. The liquid phase is filtered, evaporated and the pentaerythritol is crystallized by cooling the solution. The residue of pentaerythritol filtered, washed of impurities of sodium formiate, additionally Eataly, that facilitates the processes of filtration, washing and drying.The disadvantage of this method is its multi-stage and the difficulty associated with the necessity of using in the process of calcium hydroxide in the form of milk of lime, as well as education underutilized by-product of calcium carbonate.Closest to the present invention is a method of producing pentaerythritol, based on the interaction of acetaldehyde with formaldehyde, taken in excess, in the presence of sodium hydroxide. Resulting reaction mass, which contains dissolved pentaerythritol, sodium formate, unreacted residue of formaldehyde, as well as a number of by-products, is subjected to a first distillation to remove unreacted residue of formaldehyde, and then evaporated. From the evaporated solution by cooling the crystallized pentaerythritol, which is filtered, washed with technological impurities, recrystallized in hot water and the wet product is dried. Drying is carried out in one stage by using air heated to 140aboutC. In the drying process of the material is also removed at the same time small carbonate calcium.The disadvantage of this method is the low efficiency of the processes of drying and removal of volatile impurities. This is because in the process of synthesis of pentaerythritol in the presence of sodium hydroxide along with the main product formed various volatile and non-volatile impurities. These impurities are partially transferred to the composition of the finished product that causes severe clumping and reduced efficiency of the processes of drying and removal of volatile impurities. The increase in the degree of drying and removal of volatile impurities can be achieved by increasing the duration of the process, but it leads to deterioration of product quality in terms of color.The proposed method of producing pentaerythritol, including the interaction of acetaldehyde with formaldehyde in the presence of sodium hydroxide, distillation and evaporation of the reaction mixture, crystallization, filtration, washing and drying of pentaerythritol, characterized in that the drying process is conducted at 45-55aboutWith up to moisture and volatiles 1,5-1,5% from the dried product highlight lumps and after grinding to particle sizes of 1-2 mm spend additional heat treatment within 3-5 with coolant heated to 160-180aboutAnd disuses the volatile impurities by reducing cachemate pentaerythritol drying and create optimal conditions for the removal of volatile impurities. This is achieved by drying processes pentaerythritol and remove volatile impurities are organized separately in two stages.In the first stage, the pentaerythritol is dried by heating the material up to 45-55aboutWith up to a residual moisture content and volatile products from 1.0 to 1.5%
In the second stage of the partially dried pentaerythritol produce lumps and after grinding to particle sizes of 1-2 mm spend additional short 3-5 with heat treatment with gaseous heat carrier heated to 160-180aboutWith and moving with a speed of 20-30 m/sThe proposed technological mode first stage of the process ensures removal of the principal amount of moisture with minimal clumping of material due to slight heating of the material.The temperature reduction at the first stage, less 45aboutWith does not further reduce clumping, in addition, significantly delaying the drying duration. A temperature increase of more than 55aboutWith leads to intense clumping of pentaerythritol. This is due to the increase in the number and strength of the phase contacts are formed between the individual particles in an overly intensive evaporation of moisture.The proposed technological mode at the second stage provides the maximum degree of removal of volatile impurities without compromising other quality products.Grinding the particles to a particle size of more than 2 mm dramatically reduces the efficiency of the process of removal of volatile impurities. Pereselenie with decreasing particle size less than 1 mm is also impractical because it does not offer the additional increase in the efficiency of removal of impurities, contributes to strong dust formation and is associated with undue energy consumption for operation of the shredder.Reducing the temperature below 160aboutWith does not provide a high degree of removal of volatile impurities even when the increase in the duration of the process. Increasing temperatures above 180aboutWith does not further improve the efficiency of the process, but degrades the quality of the finished product in terms of color.Decreasing the speed of the gaseous fluid relative to the surface of the particles less than 20 m/s satyawati. The increase in speed over 30 m/s is also undesirable because it does not provide additional reductions in the duration of heat treatment causes increased dust content of exhaust fluid and expensive process.The reduction in the duration of heat treatment is less than 3 with reduce weight desorption of volatile impurities, and delays in the process for more than 5 does not provide any additional effect, but leads to a deterioration of the color of the finished product.The proposed method can be implemented as follows.The estimated amount of formaldehyde, water, and sodium hydroxide is loaded into the reactor with a cooling jacket and a stirrer. The mixture is cooled to 12-17aboutWith and gradually metered into it calculated the amount of acetaldehyde. Due to thermal effect of the reaction temperature of the reaction mixture rises to 40-45aboutC. Then the reaction mixture was neutralized with formic acid to pH 5.5-6.5 and is subjected to distillation, for example, in the nozzle column at a pressure of 2-2,5 kg/cm2and a temperature of 125-130aboutWith in order to remove excess formaldehyde, and then evaporated under vacuum to achieve the density 1270-1300 kg/m3. Evaporated racemase (dipentaerythritol, linear and cyclic formal and others), is cooled in the mold, which is a vertical apparatus, equipped with a frame with stirring and cooling jackets. The resulting suspension is filtered, washed with water from the impurities of sodium formiate and recrystallized in hot water. The recrystallized precipitate pre-dried, for example in a tumble dryer with heated air at 45-55aboutWith up to a residual moisture content and volatile impurities 1.0 to 1.5% Then formed by drying the lumps of pentaerythritol is separated in drum thunder and pulverized in a rotary grinder until the particle size 1-2 mm Crushed material together with fine-crystalline pentaerythritol subjected to additional short-term heat treatment within 3-5 with, for example, in the apparatus with a balanced-transported material layer in a stream of hot air, heated to 160-180aboutWith and moving with a speed of 20-30 m/s the Finished product after thermal processing, containing not more than 0,07-0,08% moisture and volatile impurities, is fed into the hopper of the finished product and then Packed into bags or containers.P R I m e R 1. Charged to the reactor 5915,7 kg technical solution of formalin, Saderat. The resulting mixture was intensively stirred and cooled to 15aboutSince, then, into the reactor for 60 min gradually metered technical acetaldehyde in the number 540,4 kg After completion of the reaction the mixture (19070,1 kg) is acidified to a pH value of 6, by means of formic acid (or 75.8 kg) and subjected to distillation at a pressure equal to 0.25 MPa, and the temperature in the upper part of the column 130aboutWith the purpose of removing unreacted parts of formaldehyde.The solution leaving the bottom of the column in the number 12152,4 kg and containing 1322,9 kg of pentaerythritol, mixed with technological solutions containing pentaerythritol, and evaporated to a density equal to 1280 kg/m3. The evaporated solution in the amount of 4864,3 kg and containing 1655,9 kg dissolved pentaerythritol, sent for crystallization of pentaerythritol in molds with stirring and cooling jackets. The resulting suspension (4864,3 kg) containing 1317,9 kg of crystals of pentaerythritol, filtered, the precipitate (1635 kg) was washed with cold water, taken in the quantity of 500 kg, and subjected to recrystallization in hot water (1635 kg), filtered and optionally washed with cold water (to 673.5 kg).The washed precipitate (1132,9 kg) with a humidity of 12% sushi is ur 65aboutWith, is separated from the formed lumps (200 kg) and placed in bags or containers. Clumps of pentaerythritol, which are characterized by a high content of moisture and volatiles, return for reprocessing by dissolution and crystallization.P R I m m e R 2. Conditions analogous to example 1. The differences are that the washed residue of pentaerythritol (1132,9 kg), having a moisture content of 12% is dried in a tumble dryer with heated air at a temperature material 45aboutWith up to a residual moisture content and volatile impurities 1,5% Further from the dried material is separated lumps (60 kg), which are crushed to 2 mm, and the entire material (1000 kg) is subjected to additional heat treatment for 3 with a stream of hot gaseous fluid with a temperature of 180aboutWith and moving with a speed of 20 m/s. The finished product is sent to the hopper of the finished product, and then Packed into bags or containers.Conditions and results of the implementation of the method with other declare the parameters presented in the table.From the analysis of experimental data shows that the proposed method allows to reduce the duration of drying and removal of volatile impurities 1.7-1.9 rannie advantages allow to improve the performance of the main technological equipment, to increase the production and improve the quality of the finished product. The METHOD of producing PENTAERYTHRITOL, including the interaction of acetaldehyde with formaldehyde in the presence of sodium hydroxide, distillation and evaporation of the reaction mixture, crystallization, filtration, washing and drying of pentaerythritol, characterized in that the drying process is carried out at 45 - 55oWith up to moisture content and volatile products from 1.0 to 1.5%, from the dried product highlight lumps and after grinding to particle sizes of 1 to 2 mm spend additional heat treatment for 3 to 5 with the heat carrier heated to 160 - 180oWith and moving with a speed of 20 - 30 m/s
FIELD: concentration of pentaerythrite formate mother liquors in the multi-case evaporation plant with vertical heat exchange tubes for production of high-quality lacquers, additives for oils and other products.
SUBSTANCE: proposed method includes concentration of pentaerythrite formate mother liquors at the first stage by evaporation to saturation state by pentaerythrite and crystallization of pentaerythrite from saturated solution; concentration at the first stage is performed at film flow solution; crystallization is carried out at two stages at forced circulation of suspension thus formed. Secondary vapor is divided into two flows after first stage of evaporation: one flow is delivered to the first stage of crystallization and second flow is delivered to the second stage of crystallization. At the second stage of crystallization boiling point of suspension is maintained at temperature of 45-53°C which is below that at the first stage by 7-20°C. Evaporation plant for processing the pentaerythrite formate mother liquors has two stages of evaporators connected in succession in way of flow of vapor and solution and provided with vertical tubes. Second stage of evaporation plant is just crystallizer provided with circulating loop with pump and vapor separator connected with final condenser by means of vapor pipe line. First stage consists of film liquid flow evaporator; second stage is provided with additional crystallizer with circulating loop and pump and additional condenser connected with vapor separator of additional crystallizer; it is also provided with non-condensable gas discharge unit. Last evaporator of the first stage is provided with additional pipe line for discharge of secondary vapor which is communicated with heating chamber of additional crystallizer. Solution volume of additional crystallizer exceeds that of the first one by 1.5- 2.5 times.
EFFECT: improved quality of crystalline products; increased degree of extraction of pentaerythrite from solution; increased rate of processing the solutions.
6 cl, 1 dwg, 1 tbl
SUBSTANCE: present invention relates to a method for synthesis of pentaerythritol and dipentaerythritol, involving reaction of acetaldehyde with formaldehyde in the presence of sodium hydroxide, purification of the reaction solution through distillation of excess formaldehyde, evaporation and crystallisation of technical pentaerythritol, washing the residue, recrystallisation of technical pentaerythritol, separation of the residue from the solution and drying commercial-grade pentaerythritol and treatment of the product after drying. After drying the product is treated through separation, thereby extracting the pentaerythritol fractions most contaminated with non-volatile impurities of dipentaerythritol and cyclic formalin, and the extracted fractions are processed by leaching pentaerythritol with demineralised water at 10-80°C and ratio of liquid phase to solid phase equal to (5.5-8)/1, and subsequent separation of the formed pentaerythritol solution and dipentaerythritol precipitate and taking the pentaerythritol solution to the technical pentaerythritol recrystallisation step.
EFFECT: method enables to obtain pentaerythritol with low content of dipentaerythritol and cyclic formalin impurities, as well as recycling of dipentaerythritol.
6 cl, 1 tbl, 7 ex
SUBSTANCE: present invention relates to a method of processing filtrate wastes from production of pentaerythritol, containing (wt %): 32-37.81 sodium formate, 22-27 pentaerythritol, 10-11 cyclic monoformals, 2-3 dipentaerythritol, as well as pentaerythritol derivative impurities, to obtain technical pentaerythritol and sodium formate. The method involves treatment of the filtrate with an extraction agent, followed by separation and recycling of the obtained liquid and solid phases. Treatment is carried with water in water/filtrate ration equal to (0.5-1.0)/1 and temperature 15-25°C, followed by taking the washed off residue to the evaporation and crystallisation step to obtain technical pentaerythritol and the filtrate solution for evaporation and crystallisation to obtain sodium formate.
EFFECT: efficient method of processing waste filtrate from production of pentaerythritol.
2 tbl, 1 ex
FIELD: process engineering.
SUBSTANCE: invention relates to organic synthesis, particularly, to method of processing commercial sodium pentaerythritol and formiate and may be used in chemical industry, paint-and-varnish industry, etc. Method of processing commercial sodium pentaerythritol and formiate mother solution consists in extracting pentaerythritol and liquid phase separation. Mother solution is diluted by water to content of sodium formiate of 30-32%. Then produced solution is heated to at least 60°C and mixed at said temperature for at least 4 hours at the rate of 900-1100 rpm. Then, produced suspension is filtered in vacuum filter to precipitate pentaerythritol and separate filtrate containing sodium formiate to extract the latter therefrom.
EFFECT: separate crystallisation of sodium pentaerythritol and formiate.
2 cl, 1 tbl, 1 ex
SUBSTANCE: invention relates to a method of producing pentaerythritol, involving condensation of formaldehyde with acetyldehyde in the presence of sodium hydroxide, rectification and evaporation of the condensed solution, vacuum crystallisation, filtration, washing the obtained technical pentaerythritol, recrystallisation, filtration and drying the pentaerythritol. The formaldehyde is used in form of a mixture of formalin and paraformaldehyde, where the paraformaldehyde constitutes up to 1/5 of the total amount of formaldehyde in the reaction mixture, the components being in the following molar ratio: acetaldehyde 1; formaldehyde 8.4-8.5; sodium hydroxide 1.15-1.20; water 70-72.
EFFECT: method increases efficiency of the process while ensuring high quality of the ready product.
SUBSTANCE: invention relates to a method of producing pentaerythritol which is used in production of lacquer, plastic and explosives. The method involves condensation of formaldehyde with acetaldehyde in the presence of sodium hydroxide, crystallisation, filtration and drying the pentaerythritol. The formaldehyde source used is paraformaldehyde in form of granules, into which water is added at temperature 40±2°C and stirred for 4.5-5.5 minutes. Paraformaldehyde then undergoes preliminary dissolution in an alkaline sodium hydroxide solution, said paraformaldehyde being taken in amount of 30% of the total weight of sodium hydroxide, for 15-16.5 minutes at temperature 40-45°C. Further, acetaldehyde cooled to -10±0.1°C and a residual amount of sodium hydroxide are added under cooling conditions, and pulled out for 15 minutes while gradually raising temperature of the condensed solution to 60°C. Formic acid is added to the condensed solution until pH 6.5 is achieved.
EFFECT: high effectiveness of the process while ensuring the required quality of the product.
1 tbl, 1 ex
SUBSTANCE: present invention relates to a method of purifying raw polymethylol, which contains polymethylol of formula (I), as well as a hydroxy acid of formula (IV). According to the present method, raw polymethylol is obtained in a multistep process, wherein at step (a) alkanals react via aldol condensation with formaldehyde in the presence of tertiary amines as catalyst to form methylol alkanals of formula (II). Further, at step (b), the reaction mixture obtained at step (a) is divided by distillation into a still residue primarily containing compounds of formula (II) and a head stream containing low-boiling components. The stream coming from the bottom from step (b) is hydrogenated at step (c). The stream coming from step (c) is then distilled at step (d). Low-boiling components from the stream coming from step (c) are separated, and purification is carried out in a distillation column, wherein the bottom of the distillation column is connected to at least one evaporator with a short dwell time. In formulae , , R in each separate case independently denotes a methylol group or an alkyl group with 1-22 carbon atoms or an aryl group or an arylalkyl group with 6-22 carbon atoms.
EFFECT: method reduces losses in output of polymethylol.
12 cl, 5 ex
SUBSTANCE: invention relates to a method of distilling an aqueous polymethylol mixture containing a polymethylol of formula
a tertiary amine, water, as well as an adduct of a tertiary amine and formic acid (amine formate). According to the disclosed method, distillation is carried out in a distillation column equipped with a condenser, the lower part of the column being connected to an evaporator, wherein temperature in the lower part of the column is higher than the evaporation temperature of the monoether of formic acid and polymethylol (polymethylol formate) formed during the distillation process. In formula (I), R in each case independently denotes another methylol group or an alkyl group with 1-22 carbon atoms or an aryl or aralkyl group with 6-22 carbon atoms.
EFFECT: method enables to obtain polymethylols with low content of polymethylol formate.
14 cl, 4 ex
SUBSTANCE: water solution of sodium salt: nitrate, or halogenide, or their mixture, with the concentration from 10 wt % to the concentration below the saturation line, and with the temperature, which ensures obtaining a mixture with the temperature of 20-40°C, when it is mixed with the heated mother liquor, is introduced into the hot mother liquor, which has the technological temperature of 90-100°C; the mixture is exposed with mixing for 20-60 minutes, with the following separation of the precipitated sediment of solid pentaerythrite from the liquid salt solution. The said mother liquor and water solution of the said sodium salts are taken in a weight ratio in such a way that the concentration of sodium formiate in the mother liquor after mixing constitutes 15-30 wt %.
EFFECT: method efficiency is achieved due to the reduction of the process time and increased degree of solid pentaerythrite extraction, with the simultaneous creation of the wasteless technology with obtaining two target products.
3 cl, 4 ex
FIELD: technological processes.
SUBSTANCE: invention relates to organic synthesis, particularly to processing of pentaerythritol-formiate mother solutions, and can be used for producing sodium formiate. Method of extracting sodium formiate from pentaerythritol-formiate mother solution involves a step of extracting sodium formiate from mother solution, obtained during production of pentaerythritol, with separation of liquid phase. Separated liquid phase in form of solution containing pentaerythritol with impurities and sodium formiate on the edge of saturation at temperature of 95±5 °C is fed into vessel, mother solution, obtained during production of pentaerythritol, is added at temperature of 45±5 °C, mixture temperature is brought to 55-65 °C, mixture is held at this temperature until formation of crystals of pentaerythritol with size of not less than 150 mcm. Obtained suspension is filtered to separate released crystals of pentaerythritol and impurities. Remaining solution of sodium formiate is returned to the step of sodium formiate extracting from mother solution, obtained during production of pentaerythritol.
EFFECT: invention allows to increase efficiency of the process by increasing the amount of sodium formiate, obtained at processing of pentaerythritol-formiate mother solution.
1 cl, 3 tbl, 3 ex