SU1728240A1 - Method of phthalimide synthesis - Google Patents

Abstract

The invention relates to cyclic imides, in particular, a method for producing phthalimide, which is widely used in the chemical industry as an intermediate. The goal is to increase the yield and quality of the target product. The method is carried out by oxidation of o-xylene with an air-steam mixture in the presence of ammonia at 658-668 ° C. K and the ratio of o-xylene: air: ammonia: water 1: 30-60: 8-12: 25-30 on the catalyst of the following composition, wt.%: Vanadium oxide 5-8, antimony oxide 4-8, bismuth oxide 5-10, chromium oxide 0.3-0.8 y-alumina carrier the rest. The method provides a yield of 93.5-95.2%, purity 99.76- 99.79%. С / У с VI y oo y N O

Description

This invention relates to a method for producing phthalimide (an imide of o-phthalic acid) by the heterogeneous-catalytic reaction of the oxidative ammonolysis of o-xylene, which is widely used by the chemical industry as an intermediate product in the production of such valuable dye as indigo, retardants for the vulcanization of rubber mixtures, stabilizers and flame retardants for plastics masses, drugs, plant protection chemicals, lubricant additives and in other areas of organic synthesis and for the preparation of the compounds.

Methods for the preparation of phthalic anhydride are known, based on the oxidation of various aromatic compounds, in particular o-xylene, naphthalene or a mixture thereof. Therefore, the most promising are methods that allow one way to obtain phthalimide directly from aromatic hydrocarbons, mine the stage of phthalic anhydride.

Methods for the preparation of phthalimide by the oxidative ammonolysis of 1,2-dialkyl-substituted benzene and cyclohexane are known. When the reaction is carried out in the presence of an oxide Mo-V catalyst (supported on), the phthalimide yield does not exceed 60% of o-xylene and 35% of 1,2-dimethylcyclohexane.

In addition, in the oxidative ammonolysis of o-xylene, two-component mixed vanadium – bismuth, vanadium – antimony or vanadium – chromium catalysts supported on alumina were used. In this case, the maximum phthalimide yield using these two-component systems does not exceed 15.3 mol. % (V-Cr-oxide system), oxidative ammonolysis of o-xylene with the use of individual vanadium oxide (10%) as a catalyst, supported on alumina calcined at 1673 K, yields phthalimide 72% at 668 K, contact time the composition of the initial mixture, vol.%: o-xylene 1,6; ammonia 6.4 and air - 92.

When carrying out the reaction in the presence of a catalyst consisting of an alloy of 30% tin dioxide and 70% vanadium pentoxide and a temperature of 673 K, the ratio of the feed rates of the components (o-xylene: ammonia: air) in the initial mixture is 0.1: 0.6 : 4000, respectively, the phthalimide yield reaches 75% of the theoretical, and when the catalyst composition of the alloy is 20% titanium dioxide and 80% of vanadium pentoxide, the phthalimide yield is 72% of the theoretical, other crystalline and liquid reaction products (phthalic anhydride, maleic anhydride, o- tolunitrile, o-phtalonitr yl) are obtained in an amount of 2–3%. The yield of the combustion product of the starting o-xylene carbon dioxide is 22-23%. The gaseous reaction product also contains cyanide.

The maximum yield (75%) for the recovered hydrocarbons is achieved using non-humidified air. With the introduction of water vapor in the reaction zone selectivity

5, phthalimide decreases and the yield of o-phthalonitrile increases.

The disadvantages of the known are the low yield of the target product - phthalimide and its insufficient purity.

0 (the latter is due to the presence in the catalyzate of a difficultly separable impurity, o-phthalonitrile), the formation of significant amounts of carbon dioxide as a result of deep oxidation of the initial hydrocarbon, and also highly toxic hydrogen cyanide, the need for special purification of the phthalimide obtained, which is associated with the presence in the crystalline product in addition to phthalimide other substances, in particular o0 phthalonitrile,

The closest to the present invention is a method for producing phthalimide by vapor-phase oxidative ammonolysis of o-xylene, as a catalyst also

5, compact vanadates of tin or titanium in the presence of water vapor are used. The process is carried out at temperatures of 673-713 K, the molecular ratios of the starting components of o-xylene: water: oxygen of air: ammonia 1: 15-300: 1.0-50: 5-30. The yield of phthalimide is 80-85 mol.% And the degree of purity is 99.1-99.5 wt.%. Process performance for compact two-component V-Ti and V-Sn systems

5, respectively, equal to 28.8 g / l (cat) h and 30.7 g / l (cat) h. The yield of the combustion product of the starting o-xylene carbon dioxide is 15-20 mol%.

The disadvantages of the known method of phthalimide class 0 are the low phthalimide yield, the formation of significant amounts of carbon dioxide as a result of deep oxidation of the starting hydrocarbon, and low productivity

5 process.

The aim of the invention is to increase the yield and purity of phthalimide.

The goal is achieved by the fact that the process of oxidative ammonolysis of o-xylene in the vapor phase is carried out over a supported y-alumina - vanadium-containing catalyst with the following content of all components, wt%: vanadium oxide 5-8; antimony oxide 4-8; bismuth oxide 5-10; chromium oxide 0.3-0.8; y-alumina the rest is up to 100%.

The proposed method for the preparation of phthalimide is carried out in a flow reactor (1 m long, 40 mm in diameter) with a fluidized bed of catalyst with a loading of the last 200-300 cm 3. The process is carried out at a temperature of 658-668 K, a contact time of 4.3-4.7 s and the composition of the mixture fed to the reactor, mol.% O-xylene: air: ammonia: water 1: (30-60) :( 8- 12): (25-30). Under these conditions, with the complete conversion of o-xylene, the phthalimide yield is reached up to 95.2 mol% based on the fed hydrocarbon. The only by-product of the reaction is carbon dioxide. The output does not exceed 4.8-6.5 mol.%. The analysis of the obtained products is performed by the chromatographic method. Dedicated phthalmiimide is identified by physico-chemical constants. The practical absence of impurities in the product was proved by chromatography (sensitivity threshold of the ionization-flame detector - vol.%, The chromatogram is attached).

The choice of catalyst and process conditions, implemented in the proposed method, is based on the following.

One of the main components of most catalytic systems in the oxidative ammonolysis reaction of aromatic hydrocarbons is vanadium oxides, which are universal not only for this reaction, but also for many processes of heterogeneous oxidative catalysis. Their catalytic properties are largely determined by the valence state of vanadium. The presence of a system of ions on the V-Sb-Bi surface and under conditions of oxidative ammonolysis was confirmed by physicochemical methods.

In addition, in oxidative ammonolysis, the presence of antimony oxide in the system favors an increase in the selectivity of the process and the content of tetravalent vanadium ions in the catalyst, and bismuth oxide causes a decrease in V content (respectively, increases v4) and an increase in the total contact activity, but a decrease in its selectivity. Therefore, in the case of o-xylene oxidative ammonolysis, the most effective way is to vary the composition of the catalyst in order to optimize it.

It is known that phthalimide production is associated with the use of a catalyst containing vanadium ions in a high valence state. Stabilization of vanadium ions in a high oxidation state is achieved by modifying the V-Sb-Bi oxide catalyst. Chromium oxide is used as such a component in the proposed method, since the vanadium-chromium catalyst, unlike individual vanadium pentoxide, is practically not reduced by the reaction mixture under conditions of oxidative ammonolysis of xylene.

It is known that in the oxidative ammonolysis of o-xylene, phthalimide is obtained both directly from o-xylene and by phthalonitrile hydrolysis.

The introduction of chromium oxide into a vanadium-containing catalyst eliminates the relative oxygen deficiency and increases the proportion of the parallel path to the formation of an oxygen-containing product, phthalimide, directly from o-xylene. Reduction of the vanadium ion to the tetravalent state leads to a decrease in the phthalimide yield. In order to completely eliminate the formation of phthalonitrile, which is a hardly separable crystalline impurity, water vapor is used in the o-xylene oxidative ammonolysis process. This causes the hydrolysis of phthalonitrile to phthalimide.

In addition, studies have shown that the presence of a refractory and high-strength chromium oxide in the catalyst, which prevents sintering in the reaction conditions of the active mass, improves the performance characteristics of the contact. The term of his continuous service increased to 2 thousand hours.

Example 1. The process is carried out in a flow reactor (1 m long, 40 mm in diameter) with a fluidized bed of catalyst.

Catalyst loading 200 cm; catalyst composition, wt.%: VaOs 5; SbaOs 4; В120з 5; SgaOz 0.3; y-A120z 85.7; temperature 668 K; the molar ratio of o-xylene: air: ammonia: water is 1: 30: 8: 25; contact time of 4.3 s; 11.57 g of o-xylene was reacted in 1 h.

15.23 gphthalimide was obtained in 1 h. Phthalimide yield 94.9% of the theory per hydrocarbon; the degree of conversion of o-xylene 100%; phthalimide selectivity 94.9%; selectivity C025,1%. The purity of the target product is 99.78 wt.%.

EXAMPLE 2. The process is carried out as in Example 1.

Catalyst loading 255 cm3; catalyst composition, May. %: VaOs 6; Sb20s 5; BiaOa 7; CrH2 = 0.4; y-HbOz 81.6; temperature 658 K; the molar ratio is o-xylene: air: ammonia: water 1: 40: 10: 27; contact time 4.5 s; 11.57 g of o-xylene was reacted per hour.

15.28 gphthalimide was obtained in 1 h. The phthalimide yield was 95.2% of the theory for the taken hydrocarbon. The degree of conversion of o-xylene 100%. Phthalimide selectivity is 95.2%; selectivity for, 8%. The purity of the target product is 99.80 wt.%.

PRI me R 3. The process is carried out as in Example 1.

Catalyst loading 268 cm3; catalyst composition, May. %: VaOs 7; ZaOz 7; BiaOa 8; Cr203 0.5; y-h0s 77.5; temperature 658 K; molar ratio o-xylene: air: ammonia: water 1: 50: 11: 29; contact time 4.7 s; 10.0 g of o-xylene was reacted at 1 hour.

13 g of phthalimide was obtained in 1 hour. The yield of phthalimide was 93.8% of the theory for the taken hydrocarbon. The degree of conversion of o-xylene 100%. Phthalimide selectivity 93.8%; CO 2 selectivity 6.2%. The purity of the target product is 99.76 wt.%.

EXAMPLE 4. The process is carried out as in Example 1.

Catalyst loading 297 cm3; catalyst composition, wt.%: V2U5 8; ZaOz 8; ten; Cr203 0.8; at 73.2; temperature 668 K; contact time of 4.6 s; molar ratio o-xylene: air: ammonia: water 1: 60: 12: 30; 10.0 g of o-xylene was reacted at 1 hour.

12.97 g of phthalimide was obtained in 1 h. The yield of phthalimide was 93.5% of the theory of the taken hydrocarbon. The degree of conversion of o-xylene 100%. Phthalimide selectivity of 93.5%; C02 selectivity is 6.5%. The purity of the target product is 99.7% by weight.

PRI me R 5. The process is carried out as in Example 1.

Catalyst loading 218 cm3.

The composition of the catalyst is the same as in example 3: temperature 663 K; molar ratio o-xylene: air: ammonia: water 1: 32: 9: 26; contact time 4.4 s. 11.57 g of o-xylene was reacted per hour.

Gphthalimide was obtained in 1 h. The phthalimide yield was 95.1% of the theory per hydrocarbon. The degree of conversion of o-xylene 100%. Phthalimide selectivity is 95.1%; CO2 selectivity 4.9%. The purity of the target product is 99.80 wt.%.

Example The process is carried out as in Example 1.

Catalyst loading 213 cm.

The composition of the catalyst is the same as in example 4: temperature 663 K; molar ratio o-xylene: air: ammonia: water 1: 30: 12: 25; contact time 4.3 s. 11.57 g of o-xylene was reacted per hour.

15.28 gphthalimide was obtained in 1 h. The phthalimide yield was 95.2% of the theory for the taken hydrocarbon. The degree of conversion of o-xylene 100%. Phthalimide selectivity is 95.2%; CO2 selectivity 4.8%. The purity of the target product is 99.80 wt.%.

Example. The process is carried out as in Example 1.

Catalyst loading 226 cm3.

The composition of the catalyst is the same as in example 2, temperature 668 K; molar ratio o-xylene; air: ammonia: water 1: 35: 8: 25; contact time 4.5 s; 11,57 go-xylene in 1 h.

15.21 gphthalimide at 1 h was obtained. Phthalimide yield 94.8% of the theory for the taken hydrocarbon. The degree of conversion of o-xylene 100%. Phthalimide selectivity 94.8%; C0a selectivity is 5.2%. The purity of the target product 99,77 wt.%.

Example The process is carried out as in Example 1.

Catalyst loading 236 cm.

The composition of the catalyst is the same as in example 1; temperature 658 K; molar ratio o-xylene: air: ammonia: water 1: 30: 8: 30; contact time 4.7 s; 11.57 g of o-xylene was reacted per hour.

15.24 gphthalimide was obtained in 1 h. The phthalimide yield was 95.0% of the theory per hydrocarbon. The degree of conversion of o-xylene 100%, selectivity phthalimide 95%; selectivity for C025%. The purity of the target product is 99.79 wt.%.

EXAMPLE 9. The process is carried out as in Example 1.

Catalyst loading 268 cm3; catalyst composition, wt.%: V20s 8; ZaOz 8; coal 84; temperature 668 K; molar ratio o-xylene: air: ammonia: water 1: 50: 11: 29; contact time 4.7 s; 10.0 go-xylene was reacted in 1 hour.

9.49 g of phthalimide was obtained in 1 hour. The yield of phthalimide was 68.4% of the theory for the recovered hydrocarbon, with an o-xylene conversion rate of 76%, a selectivity of phthalonitrile of 7%, a selectivity for phthalimide of 90%, a selectivity for CO2 of 3% . The target product contains 99.5% of the basic substance and 0.5% phthalonitrile.

Example 10. The process is carried out as in Example 1.

Catalyst loading 268 cm3; catalyst composition, wt.%: V20s 8, B120z 10; ula oz 82; temperature 668 K; molar ratio o-xylene: air: ammonia: water 1: 50: 11: 29; contact time 4.7 s; 10.0 g of o-xylene were introduced into the mixture at 1 h.

11.34 g of phthalimide was obtained in 1 hour. The yield of thalimide was 81.8% of the theory per hydrocarbon with an o-xylene conversion level of 7%; phthalimide selectivity 94%; C02 activity is 6%. The purity of the target product 99,70%.

Example 11. The process is carried out as in Example 1.

Catalyst loading 268 cm3; catalyst composition, wt.%: VaOs 8; SgaOz 0.8; y-20z 91.2; temperature 668 K; molar ratio o-xylene: air: ammonia: water 1: 50: 11: 29; contact time 4.7 s; 10.0 go-xylene was reacted in 1 hour.

11.26 g of phthalimide was obtained in 1 h. The yield of phthalimide was 81.2% of the theory per hydrocarbon at an o-xylene conversion rate of 84.5%; phthalimide selectivity 96.1%; C02 selectivity 3.9%. The purity of the target product is 99.68 wt.%.

As shown in examples 9-11, when using applied two-component systems, the output of phthalimide does not exceed 81.8 mol.%

The data given in examples 1-8 indicate the significant advantages of the proposed method for the production of phthalimide in comparison with the known method: the yield of phthalimide is 10% higher than in the known method; catalyst productivity is 2.5 times more than in the known method in the proposed method, specific removal of the target product is 76.2 g with 1 liter of catalyst per 1 h (example 1) - against 28.8g / l (cat) - V-Ti catalyst (example 1) and 30.7 g / l (cat). for V-Sn catalyst (example 2) in the known; phthalimide purity is greater (99.80 wt.%) than in the known method (99.50 wt.%); The developed tribal catalysts dramatically reduce the amount of active mass compared to the compact used in the known method. In addition, the presence of the carrier improves the physical and chemical characteristics of the catalysts (surface, strength, heat resistance, thermal conductivity, cost, etc.).

In the proposed method, the concentration of excess ammonia in the initial mixture is significantly (2.5 times) reduced (to 12 mol against 30 mol per mol of o-xylene in a known method, which is also a positive fact because the use of a large excess of ammonia in the initial mixture is negative affects the economic performance of the processes, as this

increases unproductive capital and energy costs for its regeneration).

Thus / excessive increase in the concentration of the reducing agent-ammonia in

The reaction mixture is not feasible due to an increase in operating costs, as well as during the reaction on a vanadium-containing catalyst, vanadium ions are stabilized in a low oxidation state, which adversely affects the formation of phthalimide.

In the proposed method, the process temperature does not exceed 668 K, and in the known method it reaches 713 K, which leads to

increase in energy costs, and also leads to the formation of a large amount of carbon dioxide (15–20% against 4.8–6.5% in the proposed method), which makes it difficult to effectively remove the heat of reaction

and reactor control.

Claims (1)

Invention Formula The method of producing phthalimide by o-xylene oxidation with an air-steam mixture in the presence of ammonia on an oxide vanadium-containing catalyst at 658-668 K and the ratio o-xylene: air: ammonia: water 1: 30-60: 8-12: 25: 25-30, respectively characterized in that, in order to increase the yield and quality of the target product, the vanadium oxide-containing catalyst has the following composition, wt%: Vanadium Oxide 5-8 Antimony Oxide4-8 Bismuth oxide, 5-10 Chromium oxide0.3-0.8 U-alumina carrier Rest 50