Method for preparing diamino-dicyclohexyl methane

Abstract

Disclosed is a method for preparing diamino-dicyclohexyl methane (H.sub.12MDA) by hydrogenation of diamino-diphenyl methane (MDA). In the process, 4,4-MDA used as the starting material is firstly hydrogenated to prepare 4,4-H.sub.12MDA. When the activity of the catalyst is reduced, the feed is switched from 4,4-MDA to the mixture of 2,4-MDA and 4,4-MDA, and then when the conversion is stabilized, the feed is switched to 4,4-MDA again. The deactivated catalyst is activated on line by switching the feed to the mixture of 2,4-MDA and 4,4-MDA. 4,4-H.sub.12MDA having the trans-trans isomer content of 1624 wt % is produced, and the mixture of 2,4-H.sub.12MDA and 4,4-H.sub.12MDA is also produced, wherein the content of 2,4-H.sub.12MDA in the mixture is 415 wt %.

Claims

1. A continuous method for preparing diamino-dicyclohexyl methane, wherein said continuous method comprises the following steps: 1) 4,4-diamino-diphenyl methane feed is hydrogenated in a reactor packed with catalyst to prepare 4,4-diamino-dicyclohexyl methane at the conversion of 98-99.99%; 2) When the conversion in step 1) is 90-98%, the feed is switched from 4,4-diamino-diphenyl methane to a mixture of 2,4-diamino-diphenyl methane and 4,4-diamino-diphenyl methane, and the hydrogenation reaction is continued to prepare 2,4-diamino-dicyclohexyl methane and 4,4-diamino-dicyclohexyl methane; 3) After the conversion of the mixture of 2,4-diamino-diphenyl methane and 4,4-diamino-diphenyl methane in step 2) is 90% and the reaction is lasted at said conversion for 20-40 h, the feed is switched from the mixture of 2,4-diamino-diphenyl methane and 4,4-diamino-diphenyl methane to 4,4-diamino-diphenyl methane, and the hydrogenation reaction is continued to prepare 4,4-diamino-dicyclohexyl methane.

2. The continuous method as claimed in claim 1, wherein the 4,4-diamino-diphenyl methane feed is composed of 98-100 wt % 4,4-diamino-diphenyl methane, 0-2 wt % 2,4-diamino-diphenyl methane, 0-1 wt % N-methyl-4,4-diamino diphenyl methane, and 0-1 wt % other impurities, based on the total weight of the 4,4-diamino-diphenyl methane feed.

3. The continuous method as claimed in claim 1, wherein the mixture of 2,4-diamino-diphenyl methane and 4,4-diamino-diphenyl methane is composed of 83-95 wt % 4,4-diamino-diphenyl methane, 3-16 wt % 2,4-diamino-diphenyl methane, 0-1 wt % N-methyl-4,4-diamino-diphenyl methane, and 0-1 wt % other impurities, based on the total weight of the mixture.

4. The continuous method as claimed in claim 1, wherein said catalyst is a supported metal catalyst, wherein the metal is one or more selected from Group VIIIB metals, the support is one or more selected from rare earth, diatomaceous earth, alumina, activated carbon, lithium aluminate, spinel, titania, silica and silica-alumina oxides, and the weight ratio of the metal and the support is 1-10:100.

5. The continuous method as claimed in claim 1, wherein said catalyst is a mixture of Rh/Al.sub.2O.sub.3 and Ru/Al.sub.2O.sub.3, wherein the weight ratio of Rh/Ru is 1-50:1.

6. The continuous method as claimed in claim 5, wherein the amount of Rh/Al.sub.2O.sub.3 is 0.5-5 wt %, based on the total weight of the reaction solution in the reaction tank.

7. The continuous method as claimed in claim 1, wherein the 4,4-MDA feed is supplied in the presence of or in the absence of a solvent, and the concentration of 4,4-MDA in the solution is 40-60 wt %.

8. The continuous method as claimed in claim 1, wherein the mixture of 2,4-MDA and 4,4-MDA is supplied in the presence of or in the absence of a solvent, and the total concentration of 2,4-MDA and 4,4-MDA in the solution is 40-60 wt %.

9. The continuous method as claimed in claim 7, wherein said solvent comprises one or more selected from cyclohexane, dioxane, tetrahydrofuran, cyclohexylamine, dicyclohexylamine, methanol, ethanol, isopropanol, n-butanol, 2-butanol and methyl cyclohexane.

10. The continuous method as claimed in claim 1, wherein the productivity of the catalyst for 4,4-diamino-diphenyl methane in the step 1) is 0.4-1 g MDA/g cat/min, and the productivity of the catalyst for the mixture of 2,4-diamino-diphenyl methane and 4,4-diamino-diphenyl methane in the step 2) is 0.4-1 g MDA/g cat/min; and the reaction temperature of hydrogenation is 100-190 C., and the absolute reaction pressure is 5-15 MPa.

11. The continuous method as claimed in claim 2, wherein the 4,4-diamino-diphenyl methane feed is composed of 99-100wt% 4,4-diamino-diphenyl methane, 0-1wt% 2,4-diamino-diphenyl methane, 0-0.5wt% N-methyl-4,4-diamino-diphenyl methane, and 0-0.5wt% other impurities, based on the total weight of the 4,4-diamino-diphenyl methane feed.

12. The continuous method as claimed in claim 3, wherein the 4,4-diamino-diphenyl methane feed is composed of 85-95wt% 4,4-diamino-diphenyl methane, 5-15wt% 2,4-diamino-diphenyl methane, 0-0.5wt% N-methyl-4,4-diamino-diphenyl methane, and 0-0.5wt% other impurities, based on the total weight of the mixture.

13. The continuous method as claimed in claim 4, wherein the metal is one or more selected from Pt, Rh, Ru, Ir and Pd.

14. The continuous method as claimed in claim 5, wherein the weight ratio of Rh/Ru is 30-40:1, wherein the content of Rh is 3-7wt%; and the contend of Ru is 3-7wt%.

15. The continuous method as claimed in claim 14, wherein the content of Rh is 4-6wt%, and the contend of Ru is 4-6wt%.

16. The continuous method as claimed in claim 6, wherein the amount of Rh/Al.sub.2O.sub.3 is 1-3wt%.

17. The continuous method as claimed in claim 7, wherein the 4,4-MDA feed is supplied in the presence a solvent, and the concentration of 4,4-MDA in the solution is about 50wt%.

18. The continuous method as claimed in claim 8, wherein the mixture of 2,4-MDA and 4,4-MDA is supplied in the presence of a solvent, and the total concentration of 2,4-MDA and 4,4-MDA in the solution is about 50wt%.

19. The continuous method as claimed in claim 9, wherein said solvent is tetrahydrofuran.

Description

THE MODE OF CARRYING OUT THE INVENTION

(1) The present invention is further described with reference to the Examples, but should not be interpreted to be limited to these Examples.

(2) Both 4 wt % Rh/Al.sub.2O.sub.3 and 5 wt % Ru/Al.sub.2O.sub.3 are available from Johnson Matthey Plc.

(3) The starting material 4,4-MDA is Wanamine MDA-100 from WANHUA Chemical Group Co., Ltd.

(4) The MDA mixture containing 15 wt % 2,4-MDA is available from WANHUA Chemical Group Co., Ltd.

(5) The MDA mixtures containing 10 wt % and 5 wt % 2,4-MDA are respectively prepared by mixing the above-said MDA mixture containing 15 wt % 2,4-MDA with Wanamine MDA-100.

(6) The main composition of the starting materials is as shown in table 1.

(7) TABLE-US-00001 TABLE 1 The main composition of the starting materials Other starting 4,4- 2,4- NCH.sub.3-4,4- com- materials MDA/wt % MDA/wt % MDA/wt % ponents/wt % 4,4-MDA 99.5 0.35 0.15 MDA mixture 94.5 5 0.36 0.14 containing 5 wt % 2,4-MDA MDA mixture 89.5 10 0.35 0.15 containing 10 wt % 2,4-MDA MDA mixture 84.5 15 0.35 0.15 containing 15 wt % 2,4-MDA

(8) The gas chromatograph is Agilent 6980 series manufactured by Agilent Technologies, DB capillary column, FID detector temperature: 300 C., the initial column temperature: 160 C., heated to 300 C. at 10 C./min, the retention time: 20 min.

Example 1

(9) Into a 2 L volume autoclave are added 10 g of Rh(4 wt %)/Al.sub.2O.sub.3 catalyst and 0.2 g of Ru(5 wt %)/Al.sub.2O.sub.3 catalyst, along with 700 g of THF. At room temperature, the interior of the autoclave is replaced with 10 bar (absolute pressure) of N.sub.2 and H.sub.2 for three times respectively, and further pressurized to 45-50 bar (absolute pressure) by using H.sub.2. At 180 C. and 8 MPa (absolute pressure), both the feed rate and discharge rate are 10 g/min, and firstly a THF solution of 4,4-MDA (THF is 50 wt % based on the total weight of the solution) is fed. During the experiment, timing sampling is done and the samples are analyzed by gas chromatography, and the results are shown as in table 2.

(10) As shown in table 2, when the conversion of MDA is reduced to 96.66%, the feed is switched from the THF solution of 4,4-MDA to a THF solution of the MDA mixture containing 5 wt % 2,4-MDA (THF is 50 wt % based on the total weight of the solution); and after the MDA conversion of the mixture maintains at 93-95% for 20 h, the feed is switched from the mixture to the THF solution of 4,4-MDA (THF is 50 wt % based on the total weight of the solution). When the conversion of MDA is reduced to 96.73%, the feed is switched from the THF solution of 4,4-MDA to the THF solution of the MDA mixture containing 5 wt % 2,4-MDA (THF is 50 wt % based on the total weight of the solution). After the MDA conversion of the mixture maintains at 93-94% for 20 h, the feed is switched from the mixture to the THF solution of 4,4-MDA (THF is 50 wt % based on the total weight of the solution). By switching to the solution of the MDA mixture containing 5 wt % 2,4-MDA for two times, the catalyst still maintains high activity after 180 h, and when the feed is then switched to 4,4-MDA, the conversion is still above 98%, and the yield of H.sub.12MDA is above 85%.

(11) TABLE-US-00002 TABLE 2 continuous reaction results of Example 1 Content of tans-trans isomer Yield of high MDA H.sub.12MDA based on boiling Reaction conversion yield 2,4-H.sub.12MDA/H.sub.12MDA 4,4-H.sub.12MDA components time (h) (%) (%) (%) [% (wt)] (%) Feed: THF solution of 4,4-MDA 10 97.12 84.34 18.55 3.12 20 98.94 90.12 19.04 5.37 30 99.11 90.78 18.92 5.31 40 99.02 90.24 19.17 5.81 50 96.66 81.43 18.12 5.12 Feed is switched to THF solution of MDA mixture containing 5 wt % 2,4-MDA 60 93.93 73.6 4.23 19.57 5.78 70 94.85 74.57 4.18 20.13 5.98 80 94.91 74.05 4.25 20.45 6.23 Feed is switched to THF solution of 4,4-MDA 90 98.41 86.17 19.24 8.15 100 98.45 86.45 19.84 8.38 110 98.42 86.29 19.56 8.46 120 96.73 79.32 19.04 8.57 Feed is switched to THF solution of MDA mixture containing 5 wt % 2,4-MDA 130 93.74 72.89 4.21 20.35 8.37 150 93.62 72.89 4.34 20.48 8.26 Feed is switched to THF solution of 4,4-MDA 160 98.33 85.89 19.22 8.57 180 98.41 85.67 19.38 8.66

Example 2

(12) Into a 2 L volume autoclave are added 5 g of Rh(4 wt %)/Al.sub.2O.sub.3 catalyst and 0.13 g of Ru(5 wt %)/Al.sub.2O.sub.3 catalyst, along with 600 g of THF. At room temperature, the interior of the autoclave is replaced with 10 bar (absolute pressure) of N.sub.2 and H.sub.2 for three times respectively, and further pressurized to 80-85 bar (absolute pressure) by using H.sub.2. At 170 C. and 12 MPa (absolute pressure), both the feed rate and discharge rate are 10 g/min, and firstly a THF solution of 4,4-MDA (THF is 50 wt % based on the total weight of the solution) is fed. During the experiment, timing sampling is done and the samples are analyzed by gas chromatography, and the results are shown as in table 3.

(13) As shown in table 3, when the conversion of MDA is reduced to 96.21%, the feed is switched from the THF solution of 4,4-MDA to a THF solution of the MDA mixture containing 10 wt % 2,4-MDA (THF is 50 wt % based on the total weight of the solution); and after the MDA conversion of the mixture maintains at 93-95% for 30 h, the feed is switched from the mixture to the THF solution of 4,4-MDA (THF is 50 wt % based on the total weight of the solution). When the conversion of MDA is reduced to 96.11%, the feed is switched from the THF solution of 4,4-MDA to the THF solution of the MDA mixture containing 10 wt % 2,4-MDA (THF is 50 wt % based on the total weight of the solution). After the MDA conversion of the mixture maintains at 93-94% for 20 h, the feed is switched from the mixture to the THF solution of 4,4-MDA (THF is 50 wt % based on the total weight of the solution). By switching to the solution of the MDA mixture containing 10 wt % 2,4-MDA for two times, the catalyst still maintains high activity after 240 h, and when the feed is then switched to 4,4-MDA, the conversion of MDA is above 98%, and the yield of H.sub.12MDA is above 85%. After 260 h, the conversion of MDA is still up to 98.45%, but the yield of the high boiling components is increased to 8.57% due to lowering of the catalyst selectivity.

(14) TABLE-US-00003 TABLE 3 continuous reaction results of Example 2 Content of tans-trans isomer Yield of high MDA H.sub.12MDA based on boiling Reaction conversion yield 2,4-H.sub.12MDA/H.sub.12MDA 4,4-H.sub.12MDA components time (h) (%) (%) (%) [% (wt)] (%) Feed: THF solution of 4,4-MDA 10 98.78 90.05 18.35 3.08 20 98.50 90.28 18.62 5.26 40 99.01 90.62 18.77 5.15 60 98.75 90.32 19.05 5.62 80 96.21 82.93 18.07 5.79 Feed is switched to THF solution of MDA mixture containing 10 wt % 2,4-MDA 90 93.93 72.02 8.73 20.23 5.25 100 93.85 71.87 8.60 21.01 5.52 120 94.11 71.52 8.72 20.65 5.13 Feed is switched to THF solution of 4,4-MDA 130 98.27 85.57 19.32 8.01 150 98.18 85.34 19.75 8.23 170 98.32 86.07 19.49 8.28 190 96.11 78.21 19.02 8.49 Feed is switched to THF solution of MDA mixture containing 10 wt % 2,4-MDA 200 93.34 71.08 8.58 20.56 8.22 220 93.02 70.32 8.60 20.69 8.15 Feed is switched to THF solution of 4,4-MDA 240 98.31 85.35 20.81 8.41 260 98.45 84.17 20.92 8.57

Example 3

(15) Into a 2 L volume autoclave are added 15 g of Rh(4 wt %)/Al.sub.2O.sub.3 catalyst and 1 g of Ru(5 wt %)/Al.sub.2O.sub.3 catalyst, along with 500 g of THF. At room temperature, the interior of the autoclave is replaced with 10 bar (absolute pressure) of N.sub.2 and H.sub.2 for three times respectively, and further pressurized to 70-75 bar (absolute pressure) by using H.sub.2. At 180 C. and 10 MPa (absolute pressure), both the feed rate and discharge rate are 15 g/min, and firstly a THF solution of 4,4-MDA (THF is 50 wt % based on the total weight of the solution) is fed. During the experiment, timing sampling is done and the samples are analyzed by gas chromatography, and the results are shown as in table 4.

(16) As shown in table 4, when the conversion of MDA is reduced to 96.95%, the feed is switched from the THF solution of 4,4-MDA to a THF solution of the MDA mixture containing 15 wt % 2,4-MDA (THF is 50 wt % based on the total weight of the solution); and after the MDA conversion of the mixture maintains at 91-92% for 20 h, the feed is switched from the mixture to the THF solution of 4,4-MDA (THF is 50 wt % based on the total weight of the solution). When the conversion of MDA is reduced to 96.14%, the feed is switched from 4,4-MDA to the THF solution of the MDA mixture containing 15 wt % 2,4-MDA (THF is 50 wt % based on the total weight of the solution). After the MDA conversion of the mixture maintains at 91-92% for 20 h, the feed is switched from the mixture to the THF solution of 4,4-MDA (THF is 50 wt % based on the total weight of the solution). By switching to the solution of the MDA mixture containing 15 wt % 2,4-MDA for two times, after 160 h of reaction time and when the feed is switched to 4,4-MDA, the conversion of MDA still reaches 98.07%, but the yield of the high boiling components is increased to 8.92% due to lowering of the catalyst selectivity, and thus the yield of H.sub.12MDA is decreased to 84.62%.

(17) TABLE-US-00004 TABLE 4 continuous reaction results of Example 3 Content of tans-trans isomer Yield of high MDA based on boiling Reaction conversion H.sub.12MDA 2,4-H.sub.12MDA/H.sub.12MDA 4,4-H.sub.12MDA components time (h) (%) yield (%) (%) [% (wt)] (%) Feed: THF solution of 4,4-MDA 10 97.57 85.35 18.63 3.26 20 99.16 90.45 18.94 5.16 30 99.23 90.34 18.59 5.81 40 99.18 90.03 19.01 6.05 50 96.95 80.82 18.07 5.68 Feed is switched to THF solution of MDA mixture containing 15 wt % 2,4-MDA 60 91.72 67.36 12.23 21.76 5.63 70 91.64 68.24 12.40 21.13 5.54 80 91.75 68.58 12.64 21.45 5.23 Feed is switched to THF solution of 4,4-MDA 90 98.11 86.47 19.89 8.56 100 98.47 85.52 19.62 9.12 110 98.35 85.87 19.48 8.42 120 96.14 77.58 19.26 8.52 Feed is switched to THF solution of MDA mixture containing 15 wt % 2,4-MDA 130 91.61 65.38 12.42 21.51 8.58 150 91.58 65.02 12.41 21.48 8.81 Feed is switched to THF solution of 4,4-MDA 160 98.07 84.62 19.76 8.92 180 98.15 84.57 19.58 9.09

Comparative Example 1

(18) Into a 2 L volume autoclave are added 10 g of Rh(4 wt %)/Al.sub.2O.sub.3 catalyst and 0.2 g of Ru(5 wt %)/Al.sub.2O.sub.3 catalyst, along with 700 g of tetrahydrofuran (THF). At room temperature, the interior of the autoclave is replaced with 10 bar (absolute pressure) of N.sub.2 and H.sub.2 for three times respectively, and further pressurized to 45-50 bar (absolute pressure) by using H.sub.2. At 180 C. and 8 MPa (absolute pressure), a THF solution of 4,4-MDA (THF is 50 wt % based on the total weight of the solution) is fed at the feed rate of 10 g/min, and the reaction product is discharged at 10 g/min by a discharging pump. During the experiment, timing sampling is done and the samples are analyzed by gas chromatography, and the results are shown as in table 5.

(19) TABLE-US-00005 TABLE 5 continuous reaction results of Comparative Example 1 Content of tans-trans Reaction MDA H.sub.12MDA isomer based on Yield of high time conversion yield 4,4-H.sub.12MDA boiling (h) (%) (%) [% (wt)] components (%) 10 97.26 85.29 18.78 3.32 15 98.84 89.01 18.84 4.37 20 99.14 90.78 18.92 5.34 25 99.02 91.22 19.17 5.31 30 98.66 90.35 18.52 5.58 35 99.02 90.18 18.79 5.55 40 99.16 91.16 19.06 5.21 45 97.48 85.83 18.29 5.12 50 96.24 80.27 18.38 5.17 55 94.24 65.34 16.16 3.65 60 85.33 48.33 15.34 3.23 65 76.35 30.82 15.18 3.17

(20) As shown in table 5, after the reaction time reaches 45 h, the activity of the catalyst is reduced, and as the reaction continues, the conversion of MDA and the yield of H.sub.12MDA are further reduced, and the catalyst is deactivated significantly.