RU2293079C1 - Process of catalytic liquid-phase hydrogenation of 2',4',4-trinitrobenzanilide in isopropyl alcohol on high-porous palladium-containing catalyst - Google Patents

Abstract

FIELD: industrial organic synthesis.

SUBSTANCE: title process resulting in production of aromatic polyamino compounds is carried out on heating in organic solvent (lower alcohols) medium in presence of supported palladium-containing catalyst, in particular, high-porosity (porosity 80-96%) cellular catalyst consisting of α-alumina-based support with active sulfated zirconium dioxide substrate and palladium as active component in amount 0.16-0.75 wt %.

EFFECT: simplified process, eliminated catalyst/hydrogenation catalysate separation stage, prevented destruction of catalyst, prolonged lifetime of catalyst, and increased purity of desired product.

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Description

The invention relates to chemical-technological processes, for example, to petrochemical synthesis, in particular to a catalytic liquid-phase method for the hydrogenation of 2 ′, 4 ′, 4-trinitrobenzanilide (TNBA) to produce aromatic polyamino compounds that are widely used as intermediate products in the manufacture of dyes, heat-resistant polymers synthesis of high-strength fibers, etc.

A known method of hydrogenation of TNBA on coal containing palladium in amide solvents at a temperature of 298-333 K and a hydrogen pressure of 0.098-5.8 MPa (Shcheltsyn V.K., Varnikova G.V., Makova EA, etc. Journal of Organic Chemistry, 1979, vol. 15. Issue 9. S.1905-1907). The disadvantages of the method include the formation of intermediate products, erosion and destruction of palladium-containing coal contaminating the target product, as well as irretrievable losses of palladium.

A known method of hydrogenation of TNBA on a skeletal nickel catalyst (Scheltsyn V.K., Varnikova G.V., Krylova K.S. et al. - In the book: Basic organic synthesis and petrochemistry. Yaroslavl, 1981. P.89-95) . The disadvantages of this method include the low selectivity of the process and the low stability of the catalyst.

The closest in technical essence and the achieved result to the claimed one is the method of catalytic liquid-phase hydrogenation of 2 ′, 4 ′, 4-trinitrobenzanilide (TNBA) when heated in an organic solvent (lower alcohols). The process of hydrogenation of TNBA is carried out on a palladium-containing catalyst with a mass content of palladium 4% supported on powdered alumina (Dzholdasova Sh.A., Sokolova L.A., Bizhanov F.B. Recovery of 2 ′, 4 ′, 4-trinitrobenzanilide on a palladium catalyst // Proceedings of the Academy of Sciences of the Kazakh SSR. Chemical series. 1984. No. 5, p. 26-28). The disadvantages of the process are the high content of the active component (palladium 4 wt.%), High hydrogen pressure up to 4.9 MPa, the duration of the process is from 10 ... 15 to 85 ... 90 minutes.

The technical result, the achievement of which the claimed method is directed, is to reduce the content of the active component (palladium), reduce the pressure of hydrogen, reduce the duration of the reaction, simplify the process: elimination of the stage of separation of the catalyst from the hydrogenation catalysis; preventing the destruction of the catalyst, the irretrievable loss of the precious metal - palladium and obtaining a cleaner target product; increased catalyst life.

To achieve the specified technical result in the proposed method, the liquid-phase hydrogenation of 2 ′, 4 ′, 4-trinitrobenzanilide is carried out by heating in an environment of an organic solvent (lower alcohols, for example, isopropyl) on a block highly porous cellular catalyst with a porosity of at least 80 ... 96%, consisting of a carrier based on α-alumina with an active substrate of sulfated zirconia and an active component - palladium with a mass content of 0.16-0.75%.

The liquid phase hydrogenation of 2 ′, 4 ′, 4-trinitrobenzanilide (TNBA) is carried out in a reactor with a reaction zone filled with a block highly porous cellular catalyst. Block highly porous cellular material (α-Al ₂ O ₃ ) with a porosity of at least 80-96%, used as a catalyst carrier, has high aero- and hydropermeability, has a higher coefficient of external mass transfer in comparison with carriers of the honeycomb structure. The carrier is modified to form an active substrate of sulfated zirconia. The catalytically active component of the catalyst, palladium, is applied to a highly porous cellular support by impregnation from soluble salts of palladium (palladium nitrate). Heat treatment of the applied layer of palladium nitrate is carried out at a temperature of 450 ° C. The reduction of palladium oxide to a metal is carried out with molecular hydrogen at a temperature of 50 ... 55 ° C.

After the hydrogenation process, the block highly porous cellular catalyst is regenerated. The number of regenerations of a block highly porous cellular catalyst reaches fifty without loss of its initial activity.

Example 1. The hydrogenation of 2 ′, 4 ′, 4-trinitrobenzanilide (TNBA) is carried out in a reactor, which is a cylindrical tank with an inner diameter of 50 mm, made of stainless steel. An organic solvent (isopropyl alcohol) in an amount of 95 ml was charged into the reactor, 1 g of TNBA was added. A highly porous cellular catalyst weighing 22.00 g with a porosity of 80-96%, containing 0.16 wt.% Palladium, is placed in the middle part of the reactor, ensuring its immobility due to the fastening of crosses and washers. The reactor is closed with a lid, in which a pocket for a thermocouple and a fitting for introducing hydrogen are provided. Using a special clamp, the reactor is mounted on a “rocking chair” capable of producing a number of swings equal to 120-160 min ^-1 , while conditions are ensured under which the course of the reaction is not limited by the diffusion of components to the outer surface of the block highly porous cellular catalyst. Maintain a predetermined temperature in the reactor due to electric heating, allowing the hydrogenation process to be carried out at temperatures up to 200 ° C. The reactor is asbestos-insulated to prevent heat loss to the environment. The free volume of the reactor is filled with hydrogen to an initial pressure of 0.5 MPa. The reaction rate is estimated by the pressure drop in the reactor at a temperature of 64 ° C. The reaction time up to 50% conversion of the initial TNBA is 330 s, while the hydrogen pressure in this case changes from 0.5 MPa to 0.24 MPa. The reaction mass on the content of residual TNBA is analyzed by thin layer chromatography. As a result of the experiment, the following data were obtained: 50% conversion rate of the initial TNBA W _50% = 0.27 ml / s; TNBA load on the catalyst is 0.08 h ^-1 . The yield of TABA (2 ′, 4 ′, 4-triaminobenzanilide) is 99.3% of theoretical.

The results of experiments on the effect of temperature and pressure of hydrogen on the recovery process of TNBA are given in the table

Table Hydrogenation of TNBA (1 g) on VPYAPK with a sulfated substrate in isopropyl alcohol (IPA) No. p / p m, g % Pd Ro, MPa T, ° C τ 50%, s W 50%, ml / s one 21.97 0.16 0.5 70 745 0.36 2 21.90 0.16 0.5 80 465 0.56 3 21.87 0.16 0.5 83 260 0.94 four 17.63 0.75 0.7 92 98 1.79 5 17.73 0.75 0.9 94 97 2.2 6 17.54 0.75 1,1 93 96 2.24

After the tests, there was no erosion of the block highly porous cellular catalyst, this could be judged by the transparency of the reaction mass, and as a result of this: before performing analyzes for the content of the components of the reaction mass, additional filtration was not required.

The cost of TABA (2 ′, 4 ′, 4-triaminobenzanilide) is determined mainly by the cost of the catalyst used for liquid-phase hydrogenation. Experiments and calculations show that regeneration of a block palladium catalyst is almost ten times cheaper than preparing fresh, the number of regenerations of a block catalyst can reach fifty; there is no additional loss of the catalyst containing palladium, since the stage of filtering the catalyst from the reaction mixture is eliminated. All this reduces the cost of 2 ′, 4 ′, 4-triaminobenzanilide.

Claims (1)

The method of liquid-phase hydrogenation of 2 ', 4', 4-trinitrobenzanilide when heated in an environment of an organic solvent (lower alcohols) in the presence of a palladium-containing catalyst on a support, characterized in that the process is carried out on a block highly porous cellular catalyst with a porosity of at least 80 ... 96% consisting of a carrier based on α-alumina with an active substrate of sulfated zirconia and an active component - palladium with a mass content of 0.16 ... 0.75%.