RU2357950C1 - Iron (ii) phthalate process - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention refers to advanced process for making iron (II) phthalate by direct reaction of iron or its alloy and carboxylic acid with air oxygen and stimulating iodine added in intensive mechanical mixing of the reaction mixture and crushed ferriferous material with using a blade paddle mixer, wherein phthalic acid content in primary charge is taken 1.55-2.0 mole/kg. Liquid phase solvent is n-butyl alcohol. Iron is presented with crushed grey cast iron in amount 30% of the other charge weight. Stimulating iodine is dosed in amount 0.075-0.17 mole/kg. Charge process proceeds as follows: solvent, acid, crushed grey cast iron, stimulating iodine. The same process is started and proceeds in a vertical beaded mill with a blade paddle mixer rotated at 960-1440 rpm in ratio of glass beads to charge 1:1 without air sparging, but even without blocking free contact of air to intensively mixed reaction mixture in the reactor within 35-50°C and current control by sampling method to accumulate iron (II) salt in amount 1.49-1.65 mole/kg. Then in continued mixing, the reaction zone is isolated from access for air. Nitrogen is delivered to sparging within 10-30 min. Thereafter mixing is stopped, reaction mixture suspension is separated from glass beads and unreacted cast iron particles and supplied to filtering. Deposit is washed 1-2 times with liquid phase solvent and delivered to vacuum drying, further to afterpurification. Filtrate and washing solvent are supplied back to the repeated process. Filtration and following end salt deposit handling are ensured in nitrogen environment.

EFFECT: improved process of iron phthalate.

18 ex, 2 tbl

Description

The invention relates to the production of iron (II) phthalate and can be used in various fields of laboratory and industrial scale chemical practice, in scientific research and in analytical control.

A known method of producing metal carboxylates (patent GB WO 8503530, publ. 08/15/1985), according to which salts of heavy metals, including iron, and carboxylic acids, among which there are dicarboxylic acids, are obtained by electrolysis in an electrolytic bath with an electrolyte in the form of water-soluble compounds of ionic nature, for example, a salt of a strong acid and a strong inorganic base, with a cathode from a material resistant to destruction under the conditions of electrolysis (graphite, stainless steel, titanium, etc.) and an anode made Vai of the desired heavy metal. Carboxylic acid is introduced into the electrolytic bath; if it is water insoluble, then in the form of a solution in an organic solvent. The process is carried out at 0-100 ° C. If it is necessary to obtain metal carboxylates in the lower valency, an antioxidant (a derivative of hydroquinone and catechol) or a stabilizer is introduced into the electrolytic bath.

The disadvantages of this method are as follows.

1. A rather complicated composition of the electrolytic bath, from which it is necessary to extract the product and properly clean it.

2. A number of substances are involved in the process, which play a kind of auxiliary role and do not make any significant contribution to the mass of the resulting product (for example, a salt of a strong acid and a strong inorganic base, an organic solvent, derivatives of hydroquinone and catechol, a stabilizer).

3. The anode and cathode require special materials for their manufacture, which must first be obtained. Here, waste from other industries is likely to cost.

4. A rather specific electrochemical process is used, requiring its equipment, a rather individual technology, etc.

Closest to the claimed is a method of producing iron (II) formate (RF patent No. 2291856), in accordance with which 4.5-10 mol / kg of an aqueous solution of formic acid is introduced into an intensive and updated with high frequency contact with iron and (or) its alloys, partially (20.0-30.6% of the mass of the liquid phase) being in a crushed state, in the presence of 0.016-0.164 mol / kg of a stimulating additive of iodine and air sparging with a flow rate of 1.2-2.0 l / min per 1 kg of the liquid phase and the process itself begins at room temperature and is conducted in the temperature range of 45-65 ° C until the content of iron salts in the reaction mixture is 1.8-2.0 mol / kg, after which the process is stopped, the suspension of the reaction mixture is separated from heavy particles of metal or its alloy, sent for filtration, the solid salt is purified by recrystallization, and the filtrate is recycled process.

The disadvantages of this method are as follows.

1. The use of an aqueous solution of formic acid as the liquid phase of the system. Formic acid is miscible with water in any ratio, while the solubility of phthalic acid in water is only 0.54 g per 100 g of water at 14 ° C.

2. Phthalic acid is significantly higher molecular weight compared to formic acid. Therefore, with it, the indicated acid contents in the reaction mixture cannot be realized.

3. Phthalic, in contrast to formic acid, dicarboxylic. And there is no reason to believe that it will react with iron in this way.

4. Iron (II) formate is a stable compound under ordinary conditions. Whether iron (II) phthalate is as stable is not known. Therefore, there is no reason to consider similar operations on the isolation and purification of the product.

5. The known solution uses air sparging. But this is with a stable target product. The stability of iron (II) phthalate is not only not proven, but not even evaluated. Therefore, the feasibility of supplying oxygen by sparging air has no evidence base.

6. The moment of termination of the redox process in the known solution is determined by the accumulation of the product 1.8-2.0 mol / kg The solubility and other physical properties of iron (II) phthalate are largely unknown. The properties of iron (II) phthalate suspensions in the desired organic media are also unknown. All this suggests that the quantitative characteristics of the moment of termination of the oxidative process can significantly change.

7. In the known solution, a glass reactor with mechanical stirring with a paddle mixer was used. It is not at all obvious that it will be acceptable for a system with phthalic acid, that it will not have to be replaced with a bead mill, in which the dissolution of solid phthalic acid, ceteris paribus, will proceed much faster.

The objective of the proposed solution is to obtain iron (II) phthalate from iron or its alloy and phthalic acid in the presence of atmospheric oxygen and a stimulating additive by a process similar in meaning to the above with a similar hardware design.

The problem is achieved in that the content of phthalic acid in the initial charge is taken 1.55-2.0 mol / kg, n-butyl alcohol is used as a solvent of the liquid phase, and iron is ground gray cast iron in an amount of 30% by weight of the rest of the charge, the stimulating additive of iodine is dosed in an amount of 0.075-0.17 mol / kg, the loading is carried out in the sequence: solvent, acid, crushed cast iron, stimulating additive, and the process itself is started and conducted in a vertical bead mill with a paddle mixer rotated at a speed of 960- 1440 rpm, when the ratio of the mass of glass beads and the load is 1: 1 in the absence of air bubbling, but in the absence of obstacles to free contact of air with the intensively mixed reaction mixture in the reactor in the temperature range of 35-50 ° С and control along the way by sampling to the accumulation of iron (II) salt in the amount of 1.49-1.65 mol / kg, after which, without stopping mixing, isolate the reaction zone from air and nitrogen is bubbled for 10-30 minutes, after which the mixing is stopped the suspension of the reaction mixture is separated and from glass beads and unreacted particles of cast iron and sent for filtration, the precipitate is washed 1-2 times with a solvent of the liquid phase and sent to vacuum drying, then for further purification, and the filtrate and washing solvent are returned to the repeated process, with the filtering and subsequent operations work with the precipitate of the target salt is carried out in a nitrogen atmosphere.

Characteristics of the raw materials used

Steel 45 according to GOST 1050-74

Gray cast iron grade SCh 15-32 according to GOST 1412-70

Phthalic acid GOST 4556-68

n-Butyl alcohol according to GOST 6006-51

Crystalline iodine according to GOST 4159-79

The inventive process is carried out as follows. In a bead mill of the vertical type, protected from accelerated wear by a well-fitted shell along the entire height and a false bottom with a thrust bearing for the end of the shaft of the paddle mixer with the blade, it is first rectangular, and as the trapezoidal configuration wears with possible twisting of the edges in opposite directions to the opposite direction, they are introduced consisting of a solvent, phthalic acid, the bulk of the initial load in a mass ratio (including iodine) with glass beads 1: 1, as well as a fraction of broken gray cast iron with a maximum nym linear particle size of not more than 5 mm in an amount of 30% by weight of the initial charge. The stimulating additive of iodine is usually introduced last and this moment is fixed as the beginning of the redox process.

The reactor is placed in its intended socket in the frame frame, connected by a flange connection to a cover with an stuffing box, a return to the condenser cooler, a thermocouple pocket and nests for a sampler and installation of a bubbler made of elastic material with a single outlet near the upper edge of the mixer blade directly at shell walls. After completing the operation of installing the reactor in the nest of the frame frame, its body is placed in a liquid bath with a large volume of coolant, which is preheated to a predetermined temperature. Using this bath, the contents of the reactor are heated to a predetermined starting temperature, then iodine is introduced and an exothermic process is started, which very soon turns the bath from heating to cooling.

The intake of air oxygen as a process reagent comes from the gas phase, which is freely in contact with the intensively mixed mechanical stirrer by the liquid phase, with the help of the subsequent transfer of the transported liquid to the deep bottom layers, where heavy particles of crushed cast iron move. Usually the last zone does not exceed 1/3 of the total system volume.

During the process, samples are taken of the reaction mixture, in which the content of iron (II) and (III) salts, separately of iron (II) iodide and iodine, is controlled. As soon as the content of iron (II) salts reaches a value of 1.49-1.65 mol / kg (with this content, the suspension of the reaction mixture is still quite fluid and allows processing), a bubbler made of an elastic material ending in single is placed in a special socket in the reactor lid a hole in the region of the upper edge of the stirrer blade, and without stopping mixing, nitrogen is supplied to the bubbler for some time. After the last one, stirring with a paddle stirrer is stopped, the suspension of the reaction mixture is separated from the beads and unreacted particles of cast iron by passing through a mesh with 0.4 × 0.4 mm mesh sizes in the field of action of the permanent magnet, and then filtering. The precipitate is washed 2 times with certain amounts of solvent for the liquid phase, after which it is filtered, squeezed well on the filter and sent to a vacuum dryer. In this case, all operations are performed in a nitrogen environment. The primary filtrate obtained by filtration and subsequently washing solvents containing rather soluble iron (III) salt, iron (II) iodide and iodine with a small amount of dissolved iron (II) phthalate are returned to the repeated process. And the dried marsh-green product powder is placed in a hermetically sealed container with a small volume of gas space, washed with a stream of nitrogen.

Example No. 1

A vertical type bead mill with a stainless steel case with an internal diameter of 80 mm and a height of 180 mm and a wall thickness of 10 mm with a slightly spherical bottom and a flange connection with a lid containing a stuffing box for a vane-type mechanical stirrer and a temperature measuring socket was used as a reactor. , nests for a sampler and at the same time a removable bubbler for nitrogen supply at the final stage, as well as a pipe for entering the atmosphere through a reflux condenser. The mill body and bottom are protected against wear by inserting a well-fitted shell of steel 45 over the entire height (wall thickness 2.7 mm) and a false bottom with a thrust bearing for the end of the shaft of the mechanical mixer. The bubbler is made of elastic material and has a length up to the level of the upper edge of the rotating blade of the mixer. Its location near the inner surface of the shell. The same location of the sampler (with a suction element in the form of a syringe and a suction line from an elastic material resistant to the reaction mixture), as well as a pocket for a thermocouple, which is welded to the lid and immersed in the reaction mixture with a gap of the end and top edge of the mixer 5-7 mm. The agitator blade is an initially rectangular steel plate 55 × 65 mm in size, gradually working due to wear acquiring the shape of a trapezoid with rounded edges at the bottom. The gap between the shell and the side surface of the mixer is up to 7 mm. The blade thickness is 2.7 mm. When using thinner blades, twisting of the edges of the plates in the opposite direction with respect to rotation was observed. The shaft of the mixer is connected directly to the shaft of the electric motor with power up to 0.5 kW and more. Rotational speed of 1440 rpm.

This reactor has a strictly defined place on the frame frame, which ensures the same arrangement of all elements of the installation both during the course of one process and during the transition to repeated and subsequent ones.

200 g of beads, 144.7 g of n-butyl alcohol, 51.5 g of phthalic acid and 60 g of a fraction of broken gray cast iron with a maximum linear size of up to 5 mm are loaded into said reactor. The loading reactor is placed in a nest on a frame frame, connected to the lid, a water bath preheated to 35 ° C is brought in, mechanical stirring is started, and after 5 min (3.8 g of ground iodine are introduced through the nest of the sampler nest). This moment is taken as the beginning of the process. The latter begins almost immediately after the introduction of a stimulating additive, which is easily fixed by the increase in temperature of the reaction mixture. The latter quickly reaches the temperature of the coolant in the bath and exceeds it. From this moment, the heating bath turns into a cooling bath. In the considered case, the main part of the process proceeded in the temperature range 38-47 ° С.

During the process, samples of the reaction mixture are taken, which are analyzed for the content of iron (II) and iron (III) salts, separately iron (II) iodide and molecular iodine. The hole of the nest for the sampler remained open the rest of the time, making it possible for air to flow freely to the surface of the intensively mixed reaction mixture.

After 150 minutes of the process in the indicated mode, the content of iron (II) and (III) salts in the sample taken was 1.55 and 0.03 mol / kg, respectively. The nest for the sampler is closed, an elastic bubbler is inserted and a stream of nitrogen is fed into the reactor at a flow rate of 1 l / min · kg of the reaction mixture. All this is done without stopping mechanical stirring. Nitrogen sparging is carried out for 15 minutes, after which the reaction mixture with the bulk of the beads and unreacted ground cast iron is sent to a receiving tank with a grate located in the field of action of the permanent magnet.

The dimensions of the weaves of the lattice are 0.4 × 0.4 mm. All the beads and almost all unreacted cast iron that got along with the reaction mixture remain on it. Part of the latter as the heaviest solid phase remained at the bottom of the reactor. This operation is carried out in a nitrogen atmosphere.

After separation of the beads and particles of cast iron, the suspension of the reaction mixture is fed to vacuum filtration, also carried out in a nitrogen atmosphere. The filtrate containing the bulk of the iron (III) salt and iron (II) iodide, as well as some iron (II) phthalate, is returned to the repeated process. The precipitate is washed 2 times with 25 g of n-butyl alcohol. The washing solvent is also recycled. The washed and well-pressed precipitate is placed in a nitrogen-filled vacuum drying chamber and dried to constant weight under vacuum at room temperature. A marsh-green powder is obtained, which allows for rather prolonged contact with dry air. It is stored in a closed container, which is well purged with nitrogen before closing. The amount of product obtained in the process of this example is 0.30 mol, which corresponds to the consumption of 96.8% of the loaded acid to obtain it.

Examples 2-11

The reaction apparatus, the mass of the initial loading and beaten iron, the nature of the remaining components of the loading, the sequence of operations during loading, the process, monitoring the progress of the process, separating the suspension of the reaction mixture, isolating the solid phase of the product from it, washing and drying, as well as the conditions for the operations starting from the termination of the redox process, are similar to those described in example 1. They differ in the duration of mixing before introducing iodine, the initial content of phthalic acid in the load, by cial content stimulating supplements, as well as salts of iron (II) and (III) at the time of termination of the redox process. These differences and the results are summarized in table.

Characteristics of the load, process, the moment of its termination and processing of the reaction mixture Example No. 2 3 four 5 6 7 8 9 10 eleven Loading: phthalic acid, mol / kg
stimulating additives of iodine, mol / kg 1,2 1.4 1,5 1.7 2.0 1.55 1.55 1.55 1.55 1.55 0.12 0.12 0.12 0.12 0.12 0,075 0.10 0.13 0.15 0.17 The duration of mixing until the introduction of iodine, min 3 four 5 four four 3 2 7 eleven one Operating temperature range, ° С 36-54 37-51 35-50 35-47 35-44 35-49 38-50 37-49 36-48 35-48 The duration of the process in minutes to the accumulation of iron (II) salts, mol / kg of iron (III), mol / kg 138 145 162 174 159 198 182 177 183 169 0.11 0.47 1.38 1.65 1,64 1.49 1.51 1,50 1.49 1,53 1,07 0.88 0.09 0.02 0.01 0,07 0.04 0.02 0.02 0.01 The amount of obtained and selected phthalate of iron (II), mol 0.02 0,095 0.28 0.33 0.35 0.30 0.29 0.29 0.29 0.30 The degree of use of loaded phthalic acid on the target product,% 8.3 33.9 93.3 97.1 87.5 96.8 93.6 93.6 93.6 96.8

Example No. 12-18

The reaction apparatus, the mass of the initial load of the solvent, acid, crushed cast iron and stimulating additives, the ratio of the mass of beads and load, the sequence of operations during loading, process, separation of the suspension of the reaction mixture, its processing, isolation of the product, its cleaning and drying, as well as the conditions operations after the termination of the redox process are similar to those described in example 1.

They differ in the temperature ranges of the process, the speed of rotation of the mechanical stirrer, the characteristics of the moment of termination of the process, as well as the duration of mixing during bubbling of nitrogen before termination. The characteristics of the indicated differences and the results obtained are summarized in table.

The process conditions, characteristics of the moment of its termination, separation and processing of the reaction mixture Example No. 12 13 fourteen fifteen 16 17 eighteen Operating temperature range of the process, ° C 36-44 35-50 36-46 35-48 37-48 35-49 37-47 Rotational speed of a paddle mechanical stirrer, rpm 960 1260 1440 1560 1260 1260 1260 The duration of mixing until the introduction of a stimulating additive, min one four 5 5 8 12 3 Air consumption for bubbling, l / min · kg load 0.00 0.00 1.05 0.00 0.00 0.00 0.00 The duration of the process in minutes to the accumulation of salts of iron (II), mol / kg
iron (III), mol / kg 144 156 165 160 138 143 148 1,52 1,53 1,07 0.93 1.51 1,50 1.49 0.02 0.02 0.41 0.48 0,03 0,03 0,03 The duration of mixing with bubbling nitrogen, min 10 thirty 24 22 19 fourteen 23 The amount of the obtained and isolated solid product (iron (II) salt), mol 0.30 0.30 0.22 0.19 0.30 0.30 0.30 The degree of use of loaded phthalic acid on the target product,% 96.8 96.8 71.0 61.3 96.8 96.8 96.8

The positive effect of the proposed solution is as follows.

1. In the process under consideration, atmospheric oxygen is used as an oxidizing agent, i.e. available natural compound, available in sufficient quantity and not requiring any specific and all the more expensive cleaning before use.

2. Air enters the reaction apparatus in a natural way, and to the place where the interaction proceeds by capture by an intensively mixed liquid phase, which does not require any additional technological solutions in this regard.

3. The process is carried out in mild temperature conditions in fairly simple equipment without significant waste-pollution, which is completely correlated with modern requirements for low-waste and low-energy production.

4. Gray cast iron used as an iron-containing material is quite accessible, especially since you can use not only cast iron shot, but also direct waste from other industries in the form of sawdust and various fights.

5. The target product is separated from the rest of the reaction mixture by filtration and is fairly well purified by washing with a base solvent. Carrying out these operations in a nitrogen environment is not very difficult, but makes it possible to obtain a product which is rather unstable when wetted to the effect of atmospheric oxygen without using temperature effects.

6. During the process, the products that interfere with its flow are not formed and do not accumulate from the raw materials used. This allows the filtrate and washing solvent to be returned to the repeated process without any processing and concentration and significantly improves the environmental characteristics of the proposed solution.

Claims (1)

A method of producing iron (II) phthalate by direct interaction of iron or its alloy and carboxylic acid in the presence of atmospheric oxygen and iodine stimulating additives with intensive mechanical stirring of the reaction mixture and crushed iron-containing material with a paddle mixer, characterized in that the phthalic acid content in the initial charge is taken 1 , 55-2.0 mol / kg, n-butyl alcohol is used as a solvent of the liquid phase, and iron is crushed gray cast iron in an amount of 30% by weight of the rest and, a stimulating additive of iodine is dosed in an amount of 0.075-0.17 mol / kg, loading is carried out in the sequence: solvent, acid, crushed cast iron, stimulating additive, and the process itself is started and carried out in a vertical bead mill with a paddle mixer rotated with speed 960-1440 rpm, when the mass ratio of glass beads and the load is 1: 1 in the absence of air bubbling, but also in the absence of obstacles to free contact of air with the intensively mixed reaction mixture in the reactor in the temperature range of 35-50 ° С and control about the go by sampling method until the accumulation of iron (II) salt in the amount of 1.49-1.65 mol / kg, after which, without stopping mixing, isolate the reaction zone from air access and supply nitrogen to sparge for 10-30 minutes, after which the stirring is stopped, the suspension of the reaction mixture is separated from glass beads and unreacted cast iron particles and sent for filtration, the precipitate is washed 1-2 times with a solvent of a liquid phase and sent to vacuum drying, then for further purification, and the filtrate and washing solvent are returned a second process, wherein the filtering operation and post-operation with the precipitate the desired salt is carried out under a nitrogen atmosphere.