Method for hydrogenating aromatic compounds

Abstract

The present invention relates to a method for hydrogenating aromatic compounds with hydrogen in the presence of a catalyst, in which the catalyst comprises ruthenium on a zirconium oxide support material, and also the use of a catalyst comprising ruthenium on a zirconium oxide support material for hydrogenating aromatic compounds.

Claims

1. A method comprising hydrogenating a mixture 2,4- and 2,6-diaminotoluene, in which the 2,4-diaminotoluene is present in a proportion of 70 to 90% by weight, and the 2,6-diaminotoluene is present in a proportion of 10 to 30% by weight, with hydrogen in the presence of a catalyst, wherein: the catalyst comprises ruthenium on a zirconium oxide support material; the zirconium oxide support material has a BET surface area of 50 to 100 m.sup.2/g, a pore volume of 0.1 to 0.9 cm.sup.3/g, and a tapped density of 700 to 1750 kg/m.sup.3; and the catalyst has a BET surface area of 50 to 100 m.sup.2/g, a pore volume of 0.1 to 0.9 cm.sup.3/g, and a tapped density of 700 to 1750 kg/m.sup.3.

2. The method according to claim 1, wherein the method is carried out continuously.

3. The method according to claim 1, wherein the method is carried out at a temperature of 50 to 220 C.

4. The method according to claim 1, wherein the method is carried out at a hydrogen pressure of 100 to 300 bar.

5. The method according to claim 1, wherein the catalyst comprises ruthenium in an amount of 0.05 to 20% by weight, based on a total weight of the catalyst.

6. The method according to claim 1, wherein the zirconium oxide support material is present in monoclinic, tetragonal, cubic or amorphous phase or a mixed phase of these modifications.

7. The method according to claim 1, wherein the zirconium oxide support material is present in monoclinic, tetragonal or a mixed phase of these modifications.

8. The method according to claim 1, wherein the zirconium oxide support material of the catalyst has a pore size distribution in which more than 50% of the pores present are formed by mesopores having a diameter of 2 nm to 50 nm and the remainder up to 100% by macropores having a diameter>50 nm.

9. The method according to claim 1, wherein the catalyst has a pore size distribution in which more than 50% of the pores present are formed by mesopores having a diameter of 2 nm to 50 nm and the remainder up to 100% by macropores having a diameter>50 nm.

10. The method according to claim 1, wherein the zirconium oxide support material of the catalyst has a pore size distribution in which more than 40% of the pores present are formed by macropores having a diameter of >50 nm and the remainder up to 100% by mesopores having a diameter of 2 nm to 50 nm.

11. The method according to claim 1, wherein the catalyst has a pore size distribution in which more than 40% of the pores present are formed by macropores having a diameter of >50 nm and the remainder up to 100% by mesopores having a diameter of 2 nm to 50 nm.

12. The method according to claim 1, wherein the hydrogenation is conducted in an organic solvent.

13. The method according to claim 1, wherein the catalyst is present in a fixed bed.

14. The method according to claim 1, wherein the catalyst is present in a suspension.

15. The method according to claim 1, wherein in the mixture of 2,4- and 2,6-diaminotoluene, the 2,4-diaminotoluene is present in a proportion of 75 to 85% by weight, and the 2,6-diaminotoluene is present in a proportion of 15 to 25% by weight.

Description

EXAMPLES

Example 1

(1) Various catalytically active metals on Al.sub.2O.sub.3 as support were tested in the method according to the invention in the hydrogenation of toluenediamine (TDA) to methyldiaminocyclohexane (MDACH) and the conversion and selectivity were measured. The reaction conditions according to the invention were:

(2) Starting material: TDA (isomeric mixture of 2,4- and 2,6-TDA in a weight ratio of 80:20) dissolved in dioxane (25% by weight solution), temperature=170 C., hydrogen pressure=140 bar, amount of catalyst=20 mg per ml starting material. The reactions were carried out in an autoclave.

(3) The conversion and the selectivity were determined by GC analysis (GC column: RTX Amine, length=30 m, internal diameter=0.25 mm, film thickness=0.5 m) and stated as area %. Table 1 shows the results obtained after a reaction time of 180 minutes.

(4) TABLE-US-00001 TABLE 1 Metal content TDA conversion MDACH Selectivity [% by wt.] Metal [Area %] [Area %] 14.8 Mo 3.51 53.01 7.0 Co 2.66 41.59 10.3 Ni 3.78 47.32 9.9 Pd 82.48 1.66 5.0 Pt 9.00 57.80 5.0 Rh 99.21 33.45 12.1 Ru 93.56 85.87 5.0 Ir 16.36 13.09

(5) Ruthenium as catalytically active metal showed the highest selectivity at 85.87% at high conversion (93.56%).

(6) The catalyst preparation is described by way of example based on the co-catalyst. All other catalysts are prepared analogously with the corresponding metal salt solution.

(7) A bowl is charged with 10 g of aluminum oxide (NorPro no. 2009850151). 5.49 g of cobalt(II) nitrate hexahydrate is then weighed into a measuring cylinder and is diluted with 7.6 ml of distilled water. The solution is divided into four and the support material is soaked in the bowl in four steps. Between the impregnating steps, the material is homogenized with a spatula. The powder is dried for 16 h at 120 C. and subsequently calcined for 4 h at 400 C. The catalyst obtained is then reduced at 400 C. with 4 l/h H.sub.2 and 40 l N.sub.2/h for 2 h and subsequently passivated with 5% air and 95% N.sub.2 for 2 h at room temperature.

Example 2

(8) The catalytically active metal ruthenium was tested on various support materials by hydrogenating toluenediamine (TDA) to methyldiaminocyclohexane (MDACH) and the conversion and selectivity were measured.

(9) The preparation of the catalyst used is described below by way of example for an inventive Ru catalyst on zirconium oxide as support material. The other catalysts mentioned in Table 2 were prepared accordingly:

(10) A measuring cylinder is charged with 30.51 g of Ru(III) nitrosyl nitrate solution (from Heraeus) and filled to a total volume of 37.5 ml with demineralized water. A ceramic bowl is then charged with 50 g of zirconium oxide powder (D9-89, BASF, BET surface area: 78 m.sup.2/g, pore volume: 0.84 ml/g, pore volume distribution: 68% macropores, 32% mesopores), the solution is added and homogeneously mixed. The powder is then dried in a circulating-air drying cabinet at 120 C. for 16 h and calcined at 200 C. for 2 h in air. The powder is then first purged with 40 l/h N.sub.2 for 20 min in a rotary tube furnace and then reduced over a period of 90 min (3 l/h hydrogen and 53 l/h nitrogen). After cooling to room temperature, the hydrogen is shut off and the powder is purged with ca. 60 l/h nitrogen. For passivation purposes, firstly 60 l/h nitrogen and 1 l/h air are added and the amount of air then slowly increases to 10 l/h (0 l/h nitrogen). It must be ensured here that the catalyst is not heated above 35 C. The active composition thus prepared is 10% by weight Ru and 90% by weight ZrO.sub.2.

(11) The catalyst has the following characteristics: tapped density is 1.13 kg/L, the pore volume (Hg porosimetry) is 0.32 ml/g, the BET surface area is 75 m.sup.2/g, the pore distribution is as follows: 0% mesopores (2-50 nm), 100% macropores (>50 nm).

(12) The reaction conditions for the hydrogenation experiments were: starting material: TDA (isomeric mixture of 2,4- and 2,6-TDA in a weight ratio of 80:20) dissolved in dioxane (25% by weight solution), temperature=170 C., hydrogen pressure=140 bar, amount of catalyst=20 mg per ml of starting material. The reactions were carried out in an autoclave.

(13) The conversion and the selectivity were determined by GC analysis (GC column: RTX Amine, length=30 m, internal diameter=0.25 mm, film thickness=0.5 m) and stated as area %. Table 2 shows the results obtained after a reaction time of 180 minutes.

(14) TABLE-US-00002 TABLE 2 TDA MDACH Ru content conversion Selectivity Support material [% by wt.] [Area %] [Area %] -Al.sub.20.sub.3 10.0 15.93 75.88 -Al.sub.20.sub.3 10.2 80.37 83.75 -, -, -Al.sub.20.sub.3 12.1 82.98 82.16 Boehmite 11.6 78.40 77.34 pseudo-Boehmite 10.4 57.78 78.25 Activated carbon 10.0 59.66 35.11 Graphite 10.0 66.19 45.95 La.sub.2O.sub.3 9.7 59.68 56.23 SiO.sub.2 10.0 45.11 65.99 TiO.sub.2 10.0 16.80 67.42 Faujasite 10.0 3.26 58.06 Cr.sub.2O.sub.3 8.9 62.02 57.49 HA (Hydroxyapatite) 11.6 23.05 72.50 ZrO.sub.2 (mixture of monoclinic, 10.0 40.06 85.87 tetragonal)

(15) The catalyst according to the invention comprising ruthenium on zirconium oxide as support material showed an excellent selectivity with respect to the desired product.

(16) Various ZrO.sub.2 support materials were then tested and the results are shown in Table 3. The reactions were carried out according to Example 2.

(17) TABLE-US-00003 TABLE 3 BET Pore surface Support volume area Pore distribution Ru TDA MDACH designation [mL/g] [m.sup.2/g] (Mesopores:Macropores) content conversion selectivity D9-89 0.32 75 0:100 10 40 86 NorPro 0.53 83 30:70 9.6 44 87 XZ16122 D9-89 0.48 17 2:98 9.4 74 79 (1000 C.) NorPro 0.54 92 36:64 9.7 47 86 SZ31164

(18) The examples show that a low BET surface area leads to a decline in MACH selectivity and that a high BET surface area is advantageous.

(19) The hydrogenations according to examples 3 and 4 described below were carried out in a tubular reactor (internal diameter 12 mm, length 140 cm). The reactor was operated in this case in circulating mode, i.e. the output was partially recycled to the reactor such that a superficial velocity of 30 to 60 m/h was present in the reactor.

(20) The hydrogenation was carried out using pure hydrogen. The feed was selected such that the catalyst hourly space velocity in the reactor (kg(TDA solution)/(L(catalyst).Math.h) reaches the specified value. The hydrogen was supplied in a pressure-regulated manner at the specified pressure. The reaction temperatures are likewise specified.

Example 3

Comparative

(21) In this comparative example, the deactivation tendency of a catalyst comprising 1% by weight of ruthenium on a gamma-aluminum oxide support material was tested in the hydrogenation of toluenediamine (TDA) to methyldiaminocyclohexane (MDACH) and the conversion and the selectivity were measured. The reaction conditions were:

(22) Starting material: TDA (isomeric mixture of 2,4- and 2,6-TDA in a weight ratio of 80:20) dissolved in dioxane (25% by weight solution), temperature=170 C., hydrogen pressure=190 bar, catalyst hourly space velocity=0.5 kg.sub.starting material.Math.L.sub.catalyst.sup.1.Math.h.sup.1, superficial velocity 44 m/h.

(23) The conversion and the selectivity were determined by GC analysis (GC column: RTX Amine, length=30 m, internal diameter=0.25 mm, film thickness=0.5 m) and stated as area %. Table 4 shows the results obtained as a function of the reaction time.

(24) TABLE-US-00004 TABLE 4 TDA MDACH Time conversion Selectivity [h] [Area %] [Area %] 22 91.5 79.9 41 88.4 80.8 65 85.8 79.9 185 79.3 78.8 209 76.8 79.0 233 74.9 79.2 256 75.4 77.9 280 74.1 77.2

(25) Comparative example 3 shows that the TDA conversion after 280 hours had fallen from 91.5% (after 22 hours) to 74.1% (after 280 hours). At the same time, the MDACH selectivity declined from 79.9% to 77.2%.

Example 4

(26) Preparation of 1% by Weight Ru on ZrO.sub.2 Fixed Bed Catalyst

(27) 238 g of ZrO.sub.2 extrudates (3 mm, SZ 31108 from NorPro, BET surface area: 73 m.sup.2/g, pore volume: 0.30 ml/g, pore volume distribution: 6% macropores, 94% mesopores) are sprayed in an impregnating drum with 19.81 g of Ru(III) nitrosyl nitrate solution (15.95% by weight Ru(III) nitrosyl nitrate (from Heraeus) in dilute nitric acid), diluted with 35 ml of demineralized water.

(28) The extrudates are then dried at 120 C. for 16 h in a circulating-air drying cabinet and subsequently calcined in a muffle furnace at 180 C. for 2 h. The catalyst is then firstly reduced for 2 h at 200 C. (4 l/h H.sub.2; 40 l/h N.sub.2) and passivated with a mixture of 10% by volume of air and 90% by volume of N.sub.2 for 1 h at room temperature. The active composition thus prepared comprises 1% by weight Ru and 99% by weight zirconium oxide.

(29) The catalyst has the following characteristics: a BET surface area of 81 m.sup.2/g, a tapped density of 1.2 kg/L, a pore volume of 0.24 mL/g (determined by Hg porosimetry).

Example 5

(30) In this example according to the invention, the reaction was carried out according to comparative example 3, in which the inventive catalyst comprising 1% by weight ruthenium on a zirconium oxide support material was used, the preparation of which is shown in example 2 by way of example. The reaction conditions were:

(31) Starting material: TDA (isomeric mixture of 2,4- and 2,6-TDA in a weight ratio of 80:20) dissolved in dioxane (25% by weight solution), temperature=170 C., hydrogen pressure=190 bar, catalyst hourly space velocity=0.1 kg.sub.starting material.Math.L.sub.catalyst.sup.1.Math.h.sup.1, superficial velocity 44 m/h.

(32) The conversion and the selectivity were determined by GC analysis (GC column: RTX Amine, length=30 m, internal diameter=0.25 mm, film thickness=0.5 m) and stated as area %. Table 5 shows the results obtained as a function of the reaction time.

(33) TABLE-US-00005 TABLE 5 TDA MDACH Time conversion Selectivity [h] [Area %] [Area %] 18.0 97.9 53.2 26.0 97.6 61.0 42.0 96.6 73.3 73.0 96.8 69.2 146.0 95.5 76.1 170.0 95.3 76.0 193.5 94.9 76.3 218.5 94.6 76.7 242.0 94.1 76.1 330.0 88.2 74.5 354.0 89.5 71.8 380.5 94.4 75.4 402.0 94.8 75.4 475.0 95.6 75.4 498.0 94.9 78.0 522.5 95.4 75.8 572.5 95.6 75.5 650.0 95.0 76.5 672.0 95.5 75.8 696.5 95.6 75.5 720.0 95.5 75.5 744.0 95.4 76.1 818.0 94.8 78.1 840.0 95.2 75.8 864.0 95.2 75.8 890.0 95.2 75.9

(34) The example shows that the TDA conversion after 242 hours is 94.1% and after 890 hours is 95.2%, in which the MDACH selectivity at 242 hours and 890 hours is high and practically unchanged.

Example 6

(35) In this inventive example, the reaction was carried out according to comparative example 3, wherein the catalyst according to the invention comprising 1% by weight ruthenium on a zirconium oxide support material was used, the preparation of which is shown in Example 2 by way of example. The reaction conditions were:

(36) Starting material: TDA (isomeric mixture of 2,4- and 2,6-TDA in a weight ratio of 80:20) dissolved in methyldiaminocyclohexane (15% by weight solution), temperature=185 C., hydrogen pressure=190 bar, catalyst hourly space velocity=0.5 kg.sub.starting material.Math.L.sub.catalyst.sup.1.Math.h.sup.1, superficial velocity 44 m/h.

(37) The conversion and the selectivity were determined by GC analysis (GC column: RTX Amine, length=30 m, internal diameter=0.25 mm, film thickness=0.5 m) and stated as area %. Table 6 shows the results obtained as a function of the reaction time.

(38) TABLE-US-00006 TABLE 6 TDA conversion MDACH selectivity Time [h] [Area %] [Area %] 89 77 70 281 79 87 617 77 88 840 83 87

(39) The example shows that the hydrogenation is also possible in substance and does not lead to a decrease in the conversion and the selectivity over a period of at least 840 hours.

Example 7

(40) In this inventive example, the reaction was carried out according to comparative example 3, wherein the catalyst according to the invention comprising 2% by weight ruthenium on a zirconium oxide support material was used, the preparation of which was carried out analogously to Example 2 with correspondingly higher amount of Ru. The reaction conditions were:

(41) Starting material: TDA (isomeric mixture of 2,4- and 2,6-TDA in a weight ratio of 80:20) dissolved in methyldiaminocyclohexane (15% by weight solution), temperature=150 C., hydrogen pressure=190 bar, catalyst hourly space velocity=0.5 kg.sub.starting material.Math.L.sub.catalyst.sup.1.Math.h.sup.1, superficial velocity 44 m/h.

(42) The conversion and the selectivity were determined by GC analysis (GC column: RTX Amine, length=30 m, internal diameter=0.25 mm, film thickness=0.5 m) and stated as area %. Table 7 shows the results obtained as a function of the reaction time.

(43) TABLE-US-00007 TABLE 7 TDA conversion MDACH selectivity Time [h] [Area %] [Area %] 256 76 89 599 82 88 2993 80 85

(44) The example shows that the hydrogenation is also possible in substance and does not lead to a decrease in the conversion and the selectivity over a period of at least 2993 hours.

Example 8

(45) In this inventive example, the reaction was carried out according to comparative example 3, wherein the catalyst according to the invention comprising 5% by weight ruthenium on a zirconium oxide support material was used, the preparation of which was carried out analogously to Example 2 with correspondingly higher amount of Ru. The reaction conditions were:

(46) Starting material: TDA (isomeric mixture of 2,4- and 2,6-TDA in a weight ratio of 80:20) dissolved in methyldiaminocyclohexane (15% by weight solution), temperature=185 C., hydrogen pressure=190 bar, catalyst hourly space velocity=0.5 kg.sub.starting material.Math.L.sub.catalyst.sup.1.Math.h.sup.1 superficial velocity 44 m/h.

(47) The conversion and the selectivity were determined by GC analysis (GC column: RTX Amine, length=30 m, internal diameter=0.25 mm, film thickness=0.5 m) and stated as area %. Table 8 shows the results obtained as a function of the reaction time.

(48) TABLE-US-00008 TABLE 8 TDA conversion MDACH selectivity Time [h] [Area %] [Area %] 200 64 96 250 64 96

(49) The example shows that the hydrogenation is also possible in substance and does not lead to a decrease in the conversion and the selectivity over a period of at least 250 hours.

Example 9

(50) The continuous hydrogenation of TDA in a suspension autoclave was carried out in a 270 ml autoclave with baffles and a stirrer with 6-blade impeller. This was initially charged with 6 g of pulverulent 5% Ru/ZrO.sub.2 catalyst, prepared according to Example 4, in a mixture comprising MDACH and dioxane in a ratio of 25:75 percent by weight and hydrogen was continuously metered in at 15 NL/h. At 170 C. and 180 bar, 12 g of a solution comprising 25% by weight TDA and 75% by weight dioxane were then fed in per hour. The suspension catalyst was retained by a filter element made of sintered metal and the reaction mixture was passed continuously over the frit.

(51) The conversion and the selectivity were determined by GC analysis (GC column: RTX Amine, length=30 m, internal diameter=0.25 mm, film thickness=0.5 m) and stated as area %. Table 9 shows the results obtained as a function of the reaction time.

(52) TABLE-US-00009 TABLE 9 TDA conversion MDACH selectivity Time [h] [Area %] [Area %] 175 99.89 85.29 220 99.85 84.53 295 99.80 83.78

(53) The example shows that the hydrogenation of TDA in a continuous suspension hydrogenation is possible without significant decline in the conversion and selectivity.

Example 10

(54) The continuous hydrogenation of TDA in a suspension autoclave was carried out in a 270 ml autoclave with baffles and a stirrer with 6-blade impeller. This was initially charged with 6 g of pulverulent 1% by weight Ru/ZrO.sub.2 catalyst, prepared according to Example 4, in a mixture comprising MDACH and dioxane in a ratio of 25:75 percent by weight and hydrogen was continuously metered in at 15 NL/h. At 170 C. and 180 bar, 12 g of a solution comprising 25% by weight TDA and 75% by weight dioxane were then fed in per hour. The suspension catalyst was retained by a filter element made of sintered metal and the reaction mixture was passed continuously over the frit.

(55) The conversion and the selectivity were determined by GC analysis (GC column: RTX Amine, length=30 m, internal diameter=0.25 mm, film thickness=0.5 m) and stated as area %. Table 10 shows the results obtained as a function of the reaction time.

(56) TABLE-US-00010 TABLE 10 TDA conversion MDACH selectivity Time [h] [Area %] [Area %] 23 99.93 83.72 142 99.87 84.93 277 99.55 84.15

(57) The example shows that the hydrogenation of TDA in a continuous suspension hydrogenation is possible without significant decline in the conversion and selectivity.