Metal complex catalyst, preparation method thereof, and use thereof in preparing D,L-menthol

Abstract

The present invention discloses a metal complex catalyst, its preparing method and its application in preparing D,L-menthol, the metal complex catalyst includes weight percent elements as follows: 70-85% of Ni, 8-10% of Al, 5-10% of V, and 2-10% of Co. When this metal complex catalyst is applied in preparing D,L-menthol through thymol hydrogenation, it has the characteristics of high reaction activity and quick racemization of chiral compound. Meanwhile, a certain kind of alkali added in isomerization is the key to reducing light constituent byproduct. The whole process comes in good reaction selectivity, simple preparing technology, low production cost, and environment-friendly synthetic route.

Claims

1. A metal complex catalyst comprising the following elements of weight percentages: TABLE-US-00004 Ni 70-85% Al 8-10% V 5-10% Co 2-10%.

2. The method for preparing metal complex catalyst according to claim 1, comprising the following steps: (1) treating NiAl alloy with a dilute sodium hydroxide solution, then water-washing the treated NiAl alloy until neutral; the mass percent concentration of the dilute sodium hydroxide solution is 38%; (2) adding the NiAl alloy treated in Step (1) batch by batch into the concentrated sodium hydroxide solution for reaction, after the reaction being completed, keeping the reaction solution static and then washing to obtain intermediate; the mass percent concentration of the concentrated sodium hydroxide solution is 1525%; (3) adding vanadium nitrate solution and cobalt nitrate solution to the intermediate obtained in Step (2) for replacement reaction, after the reaction being completed, the metal complex catalyst is obtained through post-treatment.

3. The method for preparing metal complex catalyst according to claim 2, wherein: in Step (1), the weight percent content of Ni in the NiAl alloy is 50%60%, the weight percent content of Al is 40%50%.

4. The method for preparing metal complex catalyst according to claim 2, wherein: in Step (1), the mass percent concentration of the dilute sodium hydroxide solution is 5%; the treatment temperature is 2025 C., and the treatment duration is 13 hours.

5. The method for preparing metal complex catalyst according to claim 2, wherein: in Step (2), the mass percent concentration of the concentrated sodium hydroxide solution is 20%; the reaction temperature is 1025 C., and the reaction duration is 812 hours.

6. The method for preparing metal complex catalyst according to claim 2, wherein: in Step (3), the concentration of vanadium nitrate is 12 mol/L, that of cobalt nitrate is 0.51 mol/L; the molar ratio of vanadium nitrate to the Ni in the NiAl alloy is 1:815; and the molar ratio of cobalt nitrate to the Ni in the NiAl alloy is 1:3040.

7. A method for preparing D,L-menthol, comprising the following steps: (1) under the effect of the metal complex catalyst in claim 1 and hydrogen, thymol going through hydrogenation reaction, rectifying the produced hydrogenation product to obtain the D,L-menthol and residual fraction; (2) under the effect of the metal complex catalyst in claim 1 and hydrogen, the residual fraction obtained in Step (1) further going through isomerization reaction, rectifying the produced isomerization product to obtain D,L-menthol.

8. The method for preparing D,L-menthol according to claim 7, wherein: in Step (1), the pressure of hydrogenation reaction is 28 Mpa, and the temperature of that is 120220 C.

9. The method for preparing D,L-menthol according to claim 7, wherein: in Step (2), the pressure of isomerization reaction is 23 Mpa, and the temperature of that is 80120 C.; the isomerization reaction is conducted under the catalysis of alkaline, and the weight ratio of alkaline to material is 1:1030.

10. A method for preparing D,L-menthol, comprising the following steps: under the effect of the metal complex catalyst in claim 1 and hydrogen, the material containing menthol isomer going through isomerization reaction, the produced isomerization product being rectified to obtain D,L-menthol.

Description

SPECIFIC EMBODIMENTS OF THE PRESENT INVENTION

Embodiment 1: Preparing Metal Complex Catalyst A

(1) The metal complex catalyst A in this embodiment comprises 85% of Ni, 8% of Al, 5% of V, and 2% of Co (weight percentage). The synthesizing steps are as follows:

(2) (1) At 25 C., NiAl alloy was treated with sodium hydroxide solution at mass percent concentration of 5% (in the alloy, the weight percent content of Ni is 56%, that of Al is 44%) for 2 hours, water-wash until it was neutral, at this stage, the contents of NiAl alloy had no obvious change.

(3) (2) In 4 L beaker, 380 g sodium hydroxide was dissolved in 1.5 L distilled water, stirred, cooled on ice bath to 10 C. While stirring, 300 g NiAl alloy treated in Step (1) was added batch by batch in a small amount into the alkali liquor, the adding speed was controlled not to allow the solution temperature to exceed 25 C. (on ice bath). After it was fully added (it took about 2 hours), stirring was stopped, the beaker was taken away from the ice bath, the reaction solution was allowed to rise to room temperature. When the hydrogen generation was slow, the reaction solution was heated slowly on the boiling water bath (no fast temperature rise, otherwise there can be too many bubbles, and the reaction solution may spill), until the bubble generation slowed down again (about 812 hours, during this time, the volume of the solution was maintained basically constant by replenishing distilled water). Then it was kept static to allow the Ni powder to settle down, and the supernatant was poured out. Distilled water was added until it reached the original volume, the solution was stirred to allow the Ni powder to suspend, kept static again to allow the Ni powder to settle down, the supernatant was poured out. Then the Ni power was transfer to 2 L beaker, the supernatant was removed, 500 ml water solution containing 50 g sodium hydroxide was added, stirred, kept static, the supernatant was poured out. 500 ml distilled water was added again, stirred, kept static, the supernatant was poured out. It as water-washed in this way for several times until the eluate shows neutrality against the litmus paper, then water-washed for 10 more times (water-wash for about 2040 times). The supernatant was poured out, poured in 100 mL vanadium nitrate (2N) and cobalt nitrate (0.8N) solutions and stirred for 4 hours, the catalyst was allowed to settle down, the supernatant was poured out. 200 mL 95% ethanol was added, washed using decantation method for three times, and washed again using waterless ethanol for three times. The obtained metal complex catalyst was stored in grinding jar filled with waterless ethanol (no contact with air), the catalyst must be kept under the liquid surface, the metal complex catalyst A suspending in the liquid weighs about 150 g. Based on XPS analysis, the product contains 85% of Ni, 8% of Al, 5% of V, and 2% of Co.

Embodiment 2 Preparing Metal Complex Catalyst B

(4) The metal complex catalyst B in this embodiment comprises 75% of Ni, 10% of Al, 10% of V, and 5% of Co (weight percentage). The synthesizing steps are as follows:

(5) (1) At 25 C., NiAl alloy was treated with sodium hydroxide solution at mass percent concentration of 5% (in the alloy, the weight percent content of Ni is 50%, that of Al is 50%), allowed to react for 2 hours, water-wash until it was neutral.

(6) (2) In 4 L beaker, 380 g sodium hydroxide was dissolved in 1.5 L distilled water, stirred, cooled on ice bath to 10 C. While stirring, 300 g NiAl alloy treated in Step (1) was added batch by batch in a small amount into the alkali liquor, the adding speed was controlled not to allow the solution temperature to exceed 25 C. (on ice bath). After it was fully added (it took about 2 hours), stopped stirring, the beaker was taken away from the ice bath, the reaction solution was allowed to rise to room temperature. If the hydrogen generation is slow, the reaction solution was heated slowly on the boiling water bath (no fast temperature rise, otherwise there can be too many bubbles, and the reaction solution may spill), until the bubble generation slows down again (about 812 hours, during this time, the volume of the solution was maintained basically constant by replenishing distilled water). Then it was kept static to allow the Ni powder to settle down, and poured out the supernatant. Distilled water was added until it reached the original volume, the solution was stirred to allow the Ni powder to suspend, kept static again to allow the Ni powder to settle down, the supernatant was poured out. Then settled Ni powder was transferred to 2 L beaker, the supernatant was removed, 500 ml water solution containing 50 g sodium hydroxide was added, stirred, kept static, the supernatant was poured out. 500 ml distilled water was added again, stirred, kept static, the supernatant was poured out. It was water-washed in this way for several times until the eluate shows neutrality against the litmus paper, then it was water-washed for 10 more times (water-wash for about 2040 times). Supernatant was poured out, poured in 200 mL vanadium nitrate (2N) and cobalt nitrate (0.8N) solutions and stirred for 4 hours, allowed the catalyst to settle down, the supernatant was poured out. 200 mL 95% ethanol was added, washed using decantation method for three times, and washed again using waterless ethanol for three times. The obtained metal complex catalyst was stored in grinding jar filled with waterless ethanol (no contact with air), the catalyst must be kept under the liquid surface, the metal complex catalyst B suspending in the liquid weighs about 144 g. Based on XPS analysis, the product contains 75% of Ni, 10% of Al, 10% of V, and 5% of Co.

Embodiment 3 Preparing Metal Complex Catalyst C

(7) The metal complex catalyst C in this embodiment comprises consists of 80% of Ni, 8% of Al, 7% of V, and 5% of Co (weight percentage). The synthesizing steps are as follows:

(8) (1) At 25 C., NiAl alloy was treated with sodium hydroxide solution at mass percent concentration of 5% (in the alloy, the weight percent content of Ni is 54%, that of Al is 46%), allowed to react for 2 hours, water-washed until it was neutral.

(9) (2) In 4 L beaker, 380 g sodium hydroxide was dissolved in 1.5 L distilled water, stirred, cooled on ice bath to 10 C. While stirring, 300 g NiAl alloy treated in Step (1) was added batch by batch in a small amount into the alkali liquor, the adding speed was controlled not to allow the solution temperature to exceed 25 C. (on ice bath). After it was fully added (it took about 2 hours), stirring was stopped, the beaker was taken away from the ice bath, the reaction solution was allowed to rise to room temperature. If the hydrogen generation was slow, the reaction solution was heated slowly on the boiling water bath (no fast temperature rise, otherwise there can be too many bubbles, and the reaction solution may spill), until the bubble generation slowed down again (about 812 hours, during this time, the volume of the solution was maintained basically constant by replenishing distilled water). Then it was kept static to allow the Ni powder to settle down, and the supernatant was poured out. Distilled water was added until it reached the original volume, the solution was stirred to allow the Ni powder to suspend, kept static again to allow the Ni powder to settle down, the supernatant was poured out. Then transfer to 2 L beaker, the supernatant was removed, add 500 ml water solution containing 50 g sodium hydroxide, stirred, kept static, the supernatant was poured out. 500 ml distilled water was added again, stirred, kept static, the supernatant was poured out. It was water-washed in this way for several times until the eluate showed neutrality against the litmus paper, then it was water-washed for 10 more times (water-wash for about 2040 times). Supernatant was poured out, poured in 150 mL vanadium nitrate (2N) and cobalt nitrate (0.8N) solutions and stirred for 4 hours, allowed the catalyst to settle down, the supernatant was poured out. 200 mL 95% ethanol was added, washed using decantation method for three times, and washed again using waterless ethanol for three times. The obtained metal complex catalyst was stored in grinding jar filled with waterless ethanol (no contact with air), the catalyst must be kept under the liquid surface, the metal complex catalyst C suspending in the liquid weighs about 146 g. Based on XPS analysis, the product contains 80% of Ni, 8% of Al, 7% of V, and 5% of Co.

Embodiments 49 Thymol Hydrogenation Reaction

(10) Operating steps were as follows:

(11) (1) Preparation: an operator cleaned autoclave, tested pressure, checked air tightness. Modified metal complex catalyst A was washed with ethanol to dehydrate, then washed with cyclohexane to remove ethanol. The cyclohexane liquid was sealed for future use.

(12) (2) Feed material: under the condition that the autoclave was in good air tightness, thymol, cyclohexane solvent and 1.5 g metal complex catalyst A washed already were added, 0.5N sodium hydroxide was added to adjust pH to 9.

(13) (3) Replacement: Charging and discharging nitrogen were repeated for 3 times, basically empty the air in the autoclave, repeating charging and discharging nitrogen for 3 times again, basically empty the nitrogen in the autoclave, then introducing hydrogen to allow the pressure in the autoclave to reach 4 MPa.

(14) (4) Start reaction: the temperature was set to 150 C. allow autoclave to raise temperature slowly, started stirring and circulating cooling water at stirring speed of 500 r/min, when the temperature reached 180 C., adjusting the set temperature to 180 C., and raised the hydrogen pressure to 6.0 MPa. After two hours, it was sampled to test the condition of isomers to allow the contents of the isomers to reach balance, recorded the mass percent contents of the isomers, the results were as shown in Table 1.

(15) (5) Press material: after the reaction was completed, the reaction mixture was pressed out, filtered and removed catalyst, the used catalyst was sealed and stored in cyclohexane solvent for next time recycled use. The autoclave was washed to get ready for next time reaction.

(16) (6) Remove cyclohexane: cyclohexane solvent was removed by rotating and distilling the filtrate to obtain crude product of mixture of menthol isomers.

(17) (7) Distillation: the crude product of mixture of menthol isomers was distilled to remove the resolved low-boiling-point substance (preceding fraction), high-boiling-point substance (bottoms) was removed, the finished product of a mixture of menthol isomers was obtained. D,L-menthol product and residual fraction (containing small amount of D,L-menthol, neomenthol, neoisomenthol and isomenthol) were obtained through rectification.

(18) TABLE-US-00002 TABLE 1 Reaction conditions & results of embodiments 4~9 Isomer content (%) Fed material Reaction Light Light Thymol Cyclohexane time constituent constituent No. (g) (ml) (h) by-product 1 by-product 2 Neomenthol Menthol Neoisomenthol Isomenthol Thymol 4 2 30 7 1.35 1.65 23.86 60.31 2.53 9.35 5.sup.a 2 30 7 2.86 3.25 25.18 53.33 3.51 10.92 6 10 100 7 26.6 61.01 2.48 9.78 7 20 100 7 22.00 50.21 3.66 15.57 12 1.36 1.53 23.99 60.39 2.44 8.96 0.70 8 30 100 5 0.61 0.84 17.75 48.88 3.33 6.80 21.02 11.5 1.65 1.69 22.96 62.40 2.31 8.07 0.26 9 40 100 7.5 0.05 0.08 15.09 40.02 4.59 10.93 29.24 11.5 0.07 0.12 18.43 64.45 4.66 11.91 0.36 15.5 0.79 0.68 20.54 67.29 2.51 8.12 0.07 .sup.aUsed market raney nickel as catalyst.

(19) The results of Embodiments 49 show that when the metal complex catalyst of the present invention was used instead of raney nickel, the menthol content in the hydrogenation reaction is obviously improved.

Embodiments 1011 Isomerization Reaction

(20) Operating steps are as follows:

(21) (1) Preparation: a use cleaned autoclave, tested pressure, checked air tightness. Modified metal complex catalyst A was washed with ethanol to dehydrate, then washed with cyclohexane to remove ethanol. The cyclohexane liquid was sealed for future use.

(22) (2) Feed material: under the condition that the autoclave was in good air tightness, isomerization material, 100 ml cyclohexane solvent and 1.5 g metal complex catalyst A washed already were added, 0.5N sodium hydroxide was added to adjust pH to 9.

(23) (3) Replacement: an operator repeated charging and discharging nitrogen for 3 times, basically empty the air in the autoclave, repeated charging and discharging nitrogen for 3 times again, basically empty the nitrogen in the autoclave, then introduced hydrogen to allow the pressure in the autoclave to reach 2 MPa.

(24) (4) Start reaction: temperature was set to 80 C. allow autoclave to raise temperature slowly, an operator started stirring and circulating cooling water at stirring speed of 500 r/min, when the temperature reached 100 C., adjusted the set temperature to 100 C., and raised the hydrogen pressure to 3.0 MPa. After two hours, sample was taken to test the condition of isomers to allow the contents of the isomers to reach balance, recorded the mass percent contents of the isomers, the results are as shown in Table 2.

(25) (5) Press material: after the reaction was completed, the reaction mixture was pressed out, filtered and catalyst was removed, the used catalyst was sealed and stored in cyclohexane solvent for next time recycled use. The autoclave was washed to get ready for next time reaction.

(26) (6) Remove cyclohexane: cyclohexane solvent was removed by rotating and distilling the filtrate to obtain crude product of mixture of menthol isomers.

(27) (7) Distillation: the crude product of mixture of menthol isomers was removed to remove the resolved low-boiling-point substance (preceding fraction), high-boiling-point substance (bottoms) was removed, finished product of mixture of menthol isomers was obtained.

(28) TABLE-US-00003 TABLE 2 Reaction conditions & results of embodiments 10~12 Material designation/ material Isomer content (%) feeding Menthol Light Light No. amount g constituent constituent 1 constituent 2 Neomenthol Menthol Neoisomenthol Isomenthol D/L-menthol 10 Menthol Pre-reaction 0 0 6.83 20.41 2.75 70.01 10/10 mixture constituents A 10 g contents Post-reaction 0.13 0.41 20.85 68.74 2.60 7.27 34/34 constituents contents 11 Menthol Pre-reaction 0 0 83.76 8.29 7.83 0.12 4/4 mixture constituents B 10 g contents Post-reaction 0.24 0.38 24.18 67.88 2.11 5.21 32/32 constituents contents 12 D-menthol Pre-reaction 0 0 0.93 98.7 0.25 0.12 93/6 10 g constituents contents Post-reaction 0.27 0.39 21.17 70.24 3.21 4.72 35/35 constituents contents .sup.aIn Embodiments 10~12, the reaction time is 11 hours.

(29) The results of Embodiments 1012 show that when the metal complex catalyst of the present invention was used for the isomerization reaction of menthol, good results were also achieved.