CS209102B1 - Preparation method of oxidizing katalyzer - Google Patents

Description

The invention relates to an improved process for the preparation of cobalt and multicomponent catalysts consisting of cobalt, manganese and chromium and nickel or chromium and potassium additives by oxidizing a mixture of p-xylene and terephthalate methyl ester with air, oxygen or oxygen-containing gases and toluic acid monomer.

The improvement according to the invention consists in a simplified process for the preparation of cobalt and multicomponent catalysts consisting of cobalt and manganese and chromium and nickel or chromium and potassium additives and in an increased acid yield and higher selectivity of p-xy-, toluene and toluic acid terephthalic acid monomethyl ester.

To produce dimethyl terephthalic acid according to Witten, p-xylene is oxidized in the presence of a catalyst in the liquid phase with air to form toluylic acid, which is in the next step esterified with methanol to give methyl toluyl ester. The colloylic acid methyl ester obtained is further oxidized to terephthalic acid monomethyl ester. Its esterification with methanol yields terephthalic acid dimethyl ester.

In practice, this process is carried out by oxidizing the p-xylene and the methyl ester of toluylic acid with air in the presence of a catalyst consisting of a cobalt salt or a mixture of cobalt and manganese. The resulting acids are then esterified in methanol in the second step to the corresponding esters. The resulting esters are distilled off by treating the methyl ester with acid;

^R 1 ^C OK ⁺ 2

--— * / ^R1 ; ^C 0 ^ 2 Me + 2 Rg - C no.

The toluic acid is distilled off from the terephthalic acid dimethyl ester, and the ol and the p-xylene are oxidized in the first step. The terephthalic acid dimethyl ester is further processed to the degree of purity desired by distillation, extraction and the pure product is recovered by distillation. In the production of dimethyl terephthalic acid ester, mixed catalysts comprising cobalt-manganese combinations, cobalt and metals IV are known as catalysts in addition to cobalt. side group, from combinations cobalt-manganese-honey, cobalt-maiigan-nickel (DAS 2010103, DOS 2163031, DOS 2047579, German Pat. No. 24 20805, German Pat. No. 24 46823). Said multi-component catalysts sg are used in the form of naphthenates, octanoates and other higher fatty acid salts of the metals concerned or as aqueous solutions dispersed in methyl toluyl ester.

A disadvantage of said catalysts is that they are difficult to prepare. Naphthenates, octanoates and other salts of higher fatty acids are prepared through the potassium salt of the corresponding acid and the salts of the corresponding

I. R ·] “C q _H + Κ0Η _r

II. / R ₂ - C ° / ₂ Me + 2 R ₁ - C ° _K

Said preparation is difficult to neutralize fatty acids, wash the resulting catalyst and isolate it.

Catalysts prepared by dispersing aqueous solutions of the metal acetates in the methyl ester of toluyl are poorly stable and the metal component sometimes falls off in the next process of the production of dimethyl terephthalic acid, causing fouling of the process equipment,

We have found that the preparation of a cobalt catalyst and catalysts containing a number of components, such as cobalt-manganese-chromium-potassium, or cobalt-manganese-chromium-nickel, can be simplified and the oxidation of p-xylene and methyl toluyl ester takes place with these catalysts. higher yields and a higher oxidation rate than using the aforementioned catalysts consisting of. from combinations of cobalt - manganese, cobalt - manganese - copper, cobalt - manganese - nickel, or cobalt catalyst alone.

By using the mixed catalysts prepared according to the invention, consisting of combinations of cobalt-manganese-chromium-potassium, or cobalt-manganese-chromium-nickel, the formation of oxidation by-products is reduced, i.e. carbon dioxide, carbon monoxide, ootic acid, formic acid and higher boar. and the yield of the desired acids is increased.

In the preparation of the catalysts according to the invention, the difference between the boiling point of oic acid, formic acid and the corresponding fatty acid is utilized, as well as the knowledge that the catalyst in the oxidation process is in the form of complex salts.

According to the invention, cobalt acetate, formate or carbonate, or a mixture of cobalt, manganese, chromium and nickel acetates, manganese, or carbonates, or cobalt, manganese, chromium and potassium, is admixed with an equivalent amount of the corresponding fatty acid with carbon numbers 4 At a temperature of 100 to 150 ° C at a pressure of 2.6 to 101.0 kPa, crystalline bound water and an equivalent amount of acetic or formic acid are distilled off, or water and carbon dioxide are used using carbonates. The resulting catalyst is dissolved in p-xylene, a mixture of xylenes or a mixture of xylene and alcohols and a carbon number of 2 to 8, or other solvents having a carbon number of 9 to 11,

According to the invention, this form of preparation of the oxidation catalyst is suitable. Acetate, formate or cobalt carbonate or a mixture of cobalt, manganese, chromium and nickel acetates, formates and carbonates or cobalt, manganese, chromium and potassium is mixed with an equivalent amount of carboxylic acid. The mixture is heated to 100-150 [deg.] C. and crystalline-bound water and, equivalently, part of the acids are distilled off at a pressure of 10-100 mbar, with the use of carbonates, liberating carbon dioxide equivalent. The exchange reaction is accelerated by introducing air or nitrogen into the system. Add a solvent consisting of toluene or a mixture of xylenes, a mixture of xylenes and alcohols having a carbon number of 2 to 8, or a mixture of hydrocarbons having a carbon number of 9 to 11. A homogeneous solution of a cobalt fatty acid salt having a carbon number of 4 to 20 or a mixture of cobalt, manganese, chromium and nickel salts, or cobalt, manganese, chromium and potassium, fatty acids having 4 to 20 carbon atoms per molecule in the solvent used. The concentration of cobalt, manganese, chromium and nickel, or cobalt, manganese, chromium and potassium is controlled by the amount of solvent used. The solvent to product ratio is 2: 1 to 1: 1.

In the reactor, a mixture of p-xylene and toluylic acid methyl ester is oxidized by air in the presence of a cobalt-manganese catalyst component and chromium-potassium or chromium-nickel admixtures prepared according to the invention.

It is oxidized at a pressure of 0.3 to 2.0 MPa, preferably 0.45 to 0.9 MPa at a temperature of 100 to 200 ° C, preferably 130 to 180 ° C.

The resulting oxidate consists of toluylic acid, terephthalic acid mono-methyl ester, terephthalic acid methyl ester, toluylic acid methyl ester, toluylaldehyde and other oxidation products. The oxidate is then esterified with methanol. The resulting esters are separated by oxidation. The methyl ester of toluylic acid returns to the oxidation and the dimethyl ester of terephthalic acid is further processed to the desired quality product.

The advantage of preparing the oxidation catalyst is evident from the following examples.

Example 1 \

155 g of cobalt acetate and 200 g of fatty acid having a carbon number of 4 to 20 are added to a 500 ml flask equipped with a condenser. The mixture is gradually heated to 100 to 150 ° C at 2.6 to 101.0 kPa with stirring. It equally distills off the amount of acetic acid and water. 120 to 150 ml of a solvent consisting of a mixture of p-xylene and an alcohol having a carbon number of 2 to 8 are then added. The ratio of p-xylene to alcohol is 1 with 5. Violet mixing produces a homogeneous catalyst with a cobalt concentration of about 10.0% hm.

A 1.5 L stainless steel reactor was charged with 650 g of a mixture consisting of p-xylene and toluylic acid methyl ester in a 1: 1 ratio and 100 ppm of cobalt as a catalyst prepared as described above. The mixture is heated to 156 [deg.] C. and 90 l of air are supplied at 90 l / h. In the experiments with cobalt-manganese, cobalt-manganese-copper, cobalt-manganese-chromium-potassium, or cobalt-manganese-chromium-nickel catalysts, these are supplied in accordance with the quantitative data in Table 1. Oxidized for 13 hours. The oxidation effluent is discharged through a cooling device and a flow meter to the atmosphere. Every two hours, the concentration of carbon dioxide and carbon monoxide is determined by chromatography. The resulting water of reaction was separated and collected in a separator, after which the acetic acid and formic acid contents were determined. After oxidation, the oxidation mixture is homogenized and the amount of p-xylene, toluylic acid, terephthalic acid monomethyl ester and other oxidation products are determined by chromatography using an internal standard method. Terephthalic acid is determined as the acetone insoluble fraction.

Compared to the catalysts shown in Table 1, the oxidation with the catalyst prepared according to the invention results in 3 to 4% more acids, 4.2 to 5.1% less higher boilers and 1.6 to 2.3% less by-products.

Table 1

cis lo after- piece catalyst g of acid Com- lu P g higher boiling g above boiling 100 g acids g oxide g of acid toluy- acid methyl terephthalic monomethyl ester and ^; terephthalic coal- dioxide uhoT- Nate , acetic vej mrav- whomsoever First Nuodex® 100 ppm cobalt 162.90 107.00 269,90 32.60 12.07 9.20 1.98 1.20 0.21 Second Soligen 100 ppm cobalt 163.10 107.80 270.90 27.37 10.10 9.15 1.95 1.21 0.25 Third according to the invention 100 ppm cobalt 163.20 108.10 271.30 28,06 10.34 9.22 1.97 1.20 l 0.23 4th according to the invention 100 ppm cobalt 10 ppm manganese 2 ppm of chromium 0.9 ppm of potassium 160.10 135.70 295.80 28.10 9.49 9.76 1.36 0.53 0.12

Example 2

A 500 ml flask equipped with a condenser was charged with 137.5 g of cobalt formate, 28.34 g of manganese formate, 6.0 g of potassium formate and 1.6 g of potassium acetate and 220 g of fatty acids having 4 to 20 carbons. of stirring is heated gradually to 100 to 150 ° 0 at a pressure of 2.6 to 101.0 kPa. It equally distills off the amount of formic acid, acetic acid and water. 150 ml of n-butyl alcohol are added. Further mixing produces a homogeneous catalyst containing 10 wt. cobalt, 2 wt. Manganese, 0.4 wt. % of chromium and 0.18 wt. potassium.

The apparatus described in Example 1 is charged with 650 g of a 1: 1.5 mixture of p-xylene and methyl toluyl ester, 100 ppm of cobalt, 20 ppm of manganese, 4 ppm of chromium and 1.8 ppm of potassium are added as catalyst prepared as described above. The mixture is heated to 156 [deg.] C. and 90 l of air are supplied at 90 l / h. The amounts of by-products and the resulting acids are given in analogy to Example 1 in Table 2.

The results shown in Table 2 show that in the oxidation according to the invention, the yields of acids are 2.7 to 3.6% higher, the higher boilers are 2.1 to 3.0% and the by-products are 1.8 to 2, 0% lower than the catalytic systems listed in Table 2.

Table 2

cis lo after- piece catalyst g of acid Together g higher boiling g above boiling 100 g of acid g of oxygen g of acid toluy- acid methyl terephthalic and terephthalic monomethyl esters uhliči- th uholna- th acetate formic First 100 ppm cobalt 162.90 107.00 269.9C 32,61 12.07 9.20 1.98 1.20 0.21 Second according to the invention 100 ppm cobalt 20 ppm manganese 4 ppm chromium 1.8 ppm potassium 162.30 136.80 299.10 27,10 9.06 6.02 1.30 0.55 . in 0.12 Third according to the invention 100 ppm cobalt 20 ppm manganese 0.1 ppm chromium him 0.05 ppm carbon 155.90 133.20 289.1 28.4 9,82 ' 6.40 1.27 0.52 0.14

Example 3.

In a 500 ml flask fitted with a condenser, 75,83 g of manganese carbonate, 35 g of chromium ootane, 8 g of potassium ootane and 200 g of fatty acids with carbon numbers 4 to 20 are added. The mixture is gradually heated to 100 to 150 ° C at a pressure of 2.6 to 101.0 kPa. The amount of water, carbon dioxide and acetic acid is distilled off equivalently. 150 ml of aliphatic hydrocarbons having a carbon number of 6 to 11 are added. Further mixing produces a homogeneous catalyst.

The apparatus described in Example 1 is charged with 650 g of a 1: 1.5 mixture of p-xylene and methyl toluyl ester and 100 ppm of cobalt catalyst in the form of a xylene fatty acid salt solution are added. The mixture is heated to 156 [deg.] C. and 90 l of air are supplied at 90 l / h. In experiments with cobalt-manganese catalysts, cobalt-manganese-copper, cobalt-manganese-ohr-potassium and cobalt-manganese-chromium-nickel, additional components are added to the cobalt component only after 2 to 3 hours of oxidation, in accordance with quantitative data in Table 3. The amounts of acids and by-products formed are given in analogy to Example 1 in Table 3.

The results shown in Table 3 show that in the oxidation with the catalyst prepared according to the invention, the acid yields are 3.1 to 3.8% higher, the higher boilers are 2.2 to 2.3% and the by-products are 1.9 to 3.8%. 2.5% lower than the above catalyst systems in Table 3.

cis lo poku They are catalyst g of acid Together e higher vrúoioh & Above 100 g / 100 g kyselil® g oxide g of acid toluy- acid methyl monometyles- ter terephthalic and terephthalic; coal- dioxide uhol'- Nate acetate formic First 100 ppm cobalt 162.90 107.00 269.9 ) 32.60 12.07 9.20 1.98 1.20 0.21 Second according to the invention 100 ppm cobalt 50 ppm manganese 10 ppm chromium 3.6 ppm of potassium 163.60 139.00 302.6 ( I 26,00 8.59 5.30 1.23 0.52 0.29

/ τ

Example 4 ·

160 g of manganese acetate, 35 g of chromium acetate, 7.6 g of nickel carbonate and 200 g of fatty acids having a carbon number of 4 to 20 are placed in a 500-ml flask equipped with a condenser. The mixture is gradually heated to 100 to 150 ° with stirring. C at a pressure of 2.6 to 101.0 kPa. The amount of acetic acid, water and carbon dioxide is distilled off equivalently. Toluene (150 ml) was added. Further mixing produces a homogeneous catalyst.

The apparatus described in Example 1 is charged with 650 g of a mixture consisting of p-xylene and methyl toluyl ester in a ratio of 1 and 1.5, and 200 ppm of a cocatalyst catalyst in the form of a xylenic fatty acid salt solution are added. The mixture is heated to 150 ° C and 90 l of air are introduced at 90 l / h. When attempting cobalt catalysts. - manganese, cobalt - manganese - honey, cobalt - manganese - chromium - nickel, the other components are added to the cobalt component after two to three hours of oxidation, in accordance with the quantitative data in Table 4. The amounts of acids and by-products formed are given in analogy to Example 1 in Table 4. '

The results shown in Table 4 show that in the oxidation with the catalyst prepared according to the invention the acid yields are 2.6 to 3.5% higher, the higher boilers are 2.1 to 3.0 and the by-products are 1.85 to 3.5%. 2.21% lower than the above catalyst systems in Table 4.

Table 4

cis lo after- piece íatalyzátor g of acid Together δ; above: boiling g higher boiling / 100 g acids g oxide * g of acid toluy- acid methyl Thionomethyl ester of terephthal and terephthal coal- dioxide angled- Nate acetate formic First 100 ppm cobalt 162.90 107.00 269.9 0 32.60 12.07 9.20 1.98 1.20 0.21 Second according to the invention 200 ppm Co 10 ppm Mn 0.1 ppm Cr 0.05 ppm Ni 159.40 131.28 290.6 3 28.30 9.75 . 5.60 1.30 0.54 0.11 Third according to the invention 200 ppm Co 20 ppm Mn 4 ppm Cr 2 ppm Ni 161.90 134.70 296.6 i) 26.90 • 9.00 6.13 1.34 0.51 0.40 4th according to the invention 100 ppm Co 50 ppm Mn 10 ppm Cr 5 ppm Ni 164.00 140.10 304.1 0 26.60 8.74 5.45 1.30 0.54 0.33

Claims (2)

OBJECT OF THE INVENTION A process for the preparation of an oxidation catalyst based on a cobalt fatty acid salt or a mixture of cobalt, manganese, chromium, nickel or a mixture of cobalt, manganese, chromium, potassium salts, characterized in that the formates and / or carbonates of the metals are mixed with an equivalent an amount of fatty acid having a carbon number of 4 to 20, the mixture is heated to a temperature of 100 to 150 ° C at a pressure of 2.6 to 101.0 kPa to remove crystalline water and formic acid and / or acetic acid formed by reaction; and / or carbon dioxide water, the resulting product is dissolved in toluene or p-xylan or in a mixture of xylenes and alcohols having a carbon number of 2 to 8 or aliphatic hydrocarbons having a carbon number of 6 to 11 in a ratio of 2 t 1 to 1: 1. 2. A process for the preparation of a catalyst according to claim 1, characterized in that air or nitrogen is introduced into the mixture during the reaction.