PROCESS FOR THE PRODUCTION OF y - VARELOLACTONE

Abstract

The present invention provides a process for the hydrogenation of the levulinic acid to -valerolactone in a single step with a single Pt supported on hydrotalcite catalyst. The process provides conversion of -valerolactone over Pt supported hydrotalcite catalyst at room temperature (25 C.). The process provides a levulinic acid conversion of 34-100% with 20-50 bar hydrogen pressure to give -valerolactone selectivity up to 99%.

Claims

1. An improved process for the production of -valerolactone comprising the steps: a) preparing hydrotalcite support using nitrate salts of aluminium and magnesium ratio of 80:20; b) impregnation of platinum in the range 1-3% on hydrotalcite using Pt (NH3).sub.4(NO.sub.3).sub.2 as Pt precursor; c) calcinating Pt loaded hydrotalcite as obtained from step (b) at 260-550 C. in air; d) reducing Pt loaded hydrotalcite as obtained from step (c) in hydrogen gas at 260-480 C. to obtain platinum supported hydrotalcite; e) hydrogenising of 5-20% leuvlinic acid in water in presence of platinum supported hydrotalcite catalyst as obtained in step (d) in high pressure stirrer reactor at 25 C. to 100 C. and 20-50 bar hydrogen gas while stirring for a period of 2-100 h to obtain -valerolactone

2. A process accordingly to claim 1, wherein hydrogenising of leuvlinic acid (LA) is carried out at a temperature in the range between 75-100 C.

3. A process accordingly to claim 1, wherein hydrogenising of leuvlinic acid (LA) is carried out for time in the range 75-100 h.

4. A process accordingly to claim 1, wherein hydrogenising of leuvlinic acid (LA) is carried out at a pressure in the range of 40-50 bar hydrogen pressure.

5. A process accordingly to claim 1, wherein the levulinic acid concentration for its hydrogenation is preferably selected in the range 5-20%.

Description

BRIEF DESCRIPTION OF DRAWING

[0021] FIG. 1 X-ray Diffraction (XRD) of 2% Pt-hydrotalcite and calcined 2% Pt-hydrotalcite.

[0022] FIG. 2 Scanning Electron Microscope (SEM) image of 2% Pt-hydrotalcite

[0023] FIG. 3 EDAX of 2% Pt-hydrotalcite

[0024] FIG. 4 High magnification TEM image of 2% Pt-hydrotalcite

DETAILED DESCRIPTION OF THE INVENTION

[0025] The present invention provides a process for the production of -valerolactone by hydrogenation at room temperature over Pt supported on hydrotalcite catalyst which involves the following steps.

[0026] The process for the preparation of hydrotalcite comprising the steps of:

Synthesis of hydrotalcite (Al.sub.2O.sub.3/MgO ratio of 80:20)
Synthesis of hydrotalcite was carried out using precipitation of Al (NO.sub.3).sub.3. 9H.sub.2O and
Mg(NO.sub.3).sub.26H.sub.20 with NaOH and Na.sub.2CO.sub.3 solution.

[0027] The pH of the mixture was adjusted between 9-13.

[0028] The mixed solution was stirred for 30 min at room temperature.

[0029] Heating of the resultant solution was carried out in a two necked round bottom flask at 80-90 C. for 16-18 h to get a solid substance.

[0030] The solid obtained was filtered and washed with distilled water dried at 110 C. for 12 h.

[0031] In one embodiment of the present invention, an improved process for the production of -valerolactone comprising the steps: a) preparing hydrotalcite support using nitrate salts of aluminium and magnesium ratio of 80:20; b) impregnation of platinum in the range 1-3% on hydrotalcite using Pt (NH3).sub.4(NO.sub.3).sub.2 as Pt precursor; c) calcinating Pt loaded hydrotalcite as obtained from step (b) at 260-550 C. in air; d) reducing Pt loaded hydrotalcite as obtained from step (c) in hydrogen gas at 260-480 C. to obtain platinum supported hydrotalcite; e) hydrogenising of 5-20% leuvlinic acid in water in presence of platinum supported hydrotalcite catalyst as obtained in step (d) in high pressure stirrer reactor at 25 C. to 100 C. and 20-50 bar hydrogen gas while stirring for a period of 2-100 h to obtain -valerolactone

[0032] In another embodiment of the present invention, A process accordingly to claim 1, wherein hydrogenising of leuvlinic acid (LA) is carried out at a temperature in the range between 75-100 C.

[0033] In yet another embodiment of the present invention, wherein hydrogenising of leuvlinic acid (LA) is carried out for time in the range 75-100 h.

[0034] In yet another embodiment of the present invention, wherein hydrogenising of leuvlinic acid (LA) is carried out at a pressure in the range of 40-50 bar hydrogen pressure.

[0035] In another embodiment of the present invention, wherein the levulinic acid concentration for its hydrogenation is preferably selected in the range 5-20%.

Loading of Pt on Hydrotalcite:

[0036] Pt was impregnated with the above prepared hydrotalcite using the following preparation method.

[0037] Pt(NH.sub.3).sub.4(NO.sub.3).sub.2 dissolved in required amount water and added to the hydrotalcite support while stirring and continued for 1 h. The Pt supported catalyst was dried at 90 C. for 12 and calcined at 550 C. The wt. % of Pt supported on HT varied in the range between 1-3.

General Procedure for the Hydrogenation of Levulinic Acid:

[0038] Hydrogenation reactions were conducted in batch mode, in a 160 ml stainless steel autoclave (parr reactor) at various temperatures. leuvlicnic acid, catalyst (reduced in H.sub.2 at 480 C.) and water were placed inside the reactor, after which the reactor was closed. Then the system was purged with hydrogen 4 times to remove the air. The whole system was pressurized to require hydrogen pressure from 20 to 50 bars and carried hydrogenation reaction at room temperature 25 C. to 75 C. Aliquots (liquid) were withdrawn through the special sample port attached within the reactor. At the end of the reaction, the pressure was released very slowly. The catalyst particles were separated by filtration and the product was analyzed by an Agilent 7890 gas chromatograph equipped with a FID (using restek MXT WAX capillary Column 30 m0.25ID) using reference samples.

[0039] The following examples are given by way of illustration of working of the invention in actual practice and should not be constructed to limit the scope of the present invention in any way.

Example: 1

Preparation of Pt Supported Hydrotalcite (HT) Catalyst

[0040] The hydroltalcite support was prepared by co-precipitation method. The procedure as follows. Salt solution A (100 ml) containing mixture of 0.080 mole Al(NO).sub.3.9H.sub.2O and 0.020 mole Mg(NO.sub.3).sub.26H.sub.20 was added drop wise to a basic solution of B (100 ml) containing 0.05 mole Na.sub.2CO.sub.3 and 0.17 mole NaOH. The pH was maintained between 9-13 and the mixture was aged for 1 h at room temperature with continuous stirring. Later temperature was raised to 80 C. and continued for 16 to 18 h. The resulted solid was washed with deionised water and dried at 110 C. in an oven for 12 h.

[0041] The Pt was deposited by wetness impregnation method. In a typical procedure, a 20 ml solution of 0.2 g of tetramine platinum nitrate nano hydrate (Pt(NH.sub.3).sub.4(NO.sub.3).sub.2) (2% on Pt basis) was mixed with 5 g of prepared hydrotalcite support stirred at room temperature for 1 h. The mixture was later dried at 60-80 C. at a duration of 2 to 4 h. The resulted solid was dried in an air oven at 110 C. for 12 h and calcined at 550 C. for 6 h.

[0042] The obtained catalyst was denoted as 2% Pt-HT the catalyst. In the present case, the three different types of catalyst named 1% Pt-HT, 2% Pt-HT and 3% Pt-HT contains 1% (0.1 g), 2% (0.2 g), and 3% (0.3 g) of tetra mine platinum nitrate nano hydrate

[0043] The XRD pattern of the hydrotalcite and 2% Pt hydrotalcite are shown in FIG. 1. XRD pattern of HT conforms the presence of LDH structure of hydrotalcite in the sample. 2% Pt-HT catalyst structure was collapsed after calcination of Pt-supported hydrotalcite catalyst was confirmed by XRD FIG. 1. Pt nanoparticle was not shown because of very small amount and small size. The morphology of the material (2% Pt-HT) was characterized by SEM. The typical image of the 2% Pt-HT is shown in FIG. 2. From the SEM image it is clear that the hydrotalcite particles are almost in uniform shape. The EDAX of 2% Pt-HT in FIG. 3 conforms the qualitative composition of Al, Mg, O, and Pt metals. The typical TEM images of the 2% Pt-HT is shown in FIG. 4, which indicate that 2-3 nm Pt nanoparticles are well dispersed on hydrotalcite support.

Example: 2

[0044] The hydroltalcite support was prepared by co-precipitation method. The procedure as follows: Salt solution A (100 ml) containing mixture of 0.080 mole Al(NO.sub.3).sub.3.9H.sub.2O and 0.020 mole Mg(NO.sub.3).sub.26H.sub.20 was added drop wise to a basic solution of B (100 ml) containing 0.05 mole Na.sub.2CO.sub.3 and 0.17 mole NaOH. The pH was maintained between 9-13 and the mixture was aged for 1 h at room temperature with continuous stirring. Later temperature was raised to 80 C. and continued for 16 to 18 h. The resulted solid was washed with deionised water and dried at 110 C. in an oven for 12 h.

[0045] The Pt was deposited by wetness impregnation method. In a typical procedure a 20 ml solution of tetramine platinum nitrate nano hydrate (Pt (NH.sub.3).sub.4(NO.sub.3).sub.2) (1-3% on Pt basis) was mixed with 5 g of prepared hydrotalcite support stirred at room temperature for 1 h. The mixture was later dried at 60-80 C. at a duration of 2 to 4 h. The resulted solid was dried in an air oven at 110 C. for 12 h and calcined at 550 C. for 6 h.

[0046] The obtained catalyst was denoted as Pt-HT the catalyst. In the present case, the three different types of catalyst named 1% Pt-HT, 2% Pt-HT and 3% Pt-HT contains 1% (0.1 g), 2% (0.2 g), and 3% (0.3 g) of tetra mine platinum nitrate nano hydrate

[0047] Hydrogenation reactions were conducted in batch mode, in a 160 ml stainless steel autoclave (parr reactor) at various temperatures. leuvlicnic acid (5%), catalyst 0.2 g (reduced in H.sub.2 at 480 C.) and water (20 ml) were placed inside the reactor, after which the reactor was closed. Then the system was purged with hydrogen 4 times to remove the air. The whole system was pressurized to 30 bar hydrogen pressure and carried hydrogenation reaction at room temperature (25 C.) for 24 h. At the end of the reaction, the pressure was released very slowly. The catalyst particles were separated by filtration and the product was analyzed by an Agilent 7890 gas chromatograph equipped with a FID (using restek MXT WAX capillary Column 30 m0.25ID) using reference samples.

[0048] This example describes the effect of Pt loading on hydrotalcite catalyst. The results are given in Table 1.

TABLE-US-00001 TABLE 1 Conversion Selectivity/ Entry Catalyst code Catslyst Wt (g) (%) valerolactone 1 1 wt % Pt-HT 0.2 78 >99% 2 2 wt % Pt-HT 0.2 90 >99% 3 3 wt % Pt-HT 0.2 100 >99%

Example: 3

[0049] The hydroltalcite support was prepared by co-precipitation method. The procedure as follows: Salt solution A (100 ml) containing mixture of 0.080 mole Al(NO.sub.3).sub.3.9H.sub.2O and 0.020 mole Mg(NO.sub.3).sub.26H.sub.20 was added drop wise to a basic solution of B (100 ml) containing 0.05 mole Na.sub.2CO.sub.3 and 0.17 mole NaOH. The pH was maintained between 9-13 and the mixture was aged for 1 h at room temperature with continuous stirring. Later temperature was raised to 80 C. and continued for 16 to 18 h. The resulted solid was washed with deionised water and dried at 110 C. in an oven for 12 h.

[0050] The Pt was deposited by wetness impregnation method. In a typical procedure, a 20 ml solution of 0.2 g of tetramine platinum nitrate nano hydrate (Pt(NH.sub.3).sub.4(NO.sub.3).sub.2) (2% on Pt basis) was mixed with 5 g of prepared hydrotalcite support stirred at room temperature for 1 h. The mixture was later dried at 60-80 C. at a duration of 2 to 4 h. The resulted solid was dried in an air oven at 110 C. for 12 h and calcined at 550 C. for 6 h.

[0051] Hydrogenation reactions were conducted in batch mode, in a 160 ml stainless steel autoclave (parr reactor) at various temperatures. Leuvlicnic acid (5-20%), catalyst 0.2 g (reduced in H.sub.2 at 480 C.) and water (20 ml) were placed inside the reactor, after which the reactor was closed. Then the system was purged with hydrogen 4 times to remove the air. The whole system was pressurized to 50 bar hydrogen pressure and carried hydrogenation reaction at room temperature (25 C.) for 24 h. At the end of the reaction, the pressure was released very slowly. The catalyst particles were separated by filtration and the product was analyzed by an Agilent 7890 gas chromatograph equipped with a FID (using restek MXT WAX capillary Column 30 m0.25ID) using reference samples.

[0052] This example describes the effect of leuvlinic acid concentration for its conversion. The analysis results are presented in Table 2

TABLE-US-00002 TABLE 2 LA Reaction Selectivity/ Catalyst code (wt %) Time (h) Conversition valerolactone 2 wt % Pt-HT 5 24 81 >99% 2 wt % Pt-HT 10 24 60 >99% 2 wt % Pt-HT 20 24 15 >99%

Example: 4

[0053] The hydroltalcite support was prepared by co-precipitation method. The procedure as follow: Salt solution A (100 ml) containing mixture of 0.080 mole Al(NO.sub.3).sub.3.9H.sub.2O and 0.020 mole Mg(NO.sub.3).sub.26H.sub.20 was added drop wise to a basic solution of B (100 ml) containing 0.05 mole Na.sub.2CO.sub.3 and 0.17 mole NaOH. The pH was maintained between 9-13 and the mixture was aged for 1 h at room temperature with continuous stirring. Later temperature was raised to 80 C. and continued for 16 to 18 h. The resulted solid was washed with deionised water and dried at 110 C. in an oven for 12 h.

[0054] The Pt was deposited by wetness impregnation method. In a typical procedure, a 20 ml solution of 0.2 g of tetramine platinum nitrate nano hydrate (Pt(NH.sub.3).sub.4(NO.sub.3).sub.2) (2% on Pt basis) was mixed with 5 g of prepared hydrotalcite support stirred at room temperature for 1 h. The mixture was later dried at 60-80 C. at a duration of 2 to 4 h. The resulted solid was dried in an air oven at 110 C. for 12 h and calcined at 550 C. for 6 h.

[0055] Hydrogenation reactions were conducted in batch mode, in a 160 ml stainless steel autoclave (parr reactor) at various temperatures. Leuvlicnic acid (5%), catalyst 0.2 g (reduced in H.sub.2 at 480 C.) and water (20 ml) were placed inside the reactor, after which the reactor was closed. Then the system was purged with hydrogen 4 times to remove the air. The whole system was pressurized to 50 bar hydrogen pressure and carried hydrogenation reaction at room temperature (25 C.) for 2-100 h. At the end of the reaction, the pressure was released very slowly. The catalyst particles were separated by filtration and the product was analyzed by an Agilent 7890 gas chromatograph equipped with a FID (using restek MXT WAX capillary Column 30 m0.25ID) using reference samples.

[0056] This example describes the effect of reaction time on conversion of leuvliic acid conversion. The analysis results are presented in Table 3

TABLE-US-00003 TABLE 3 Reaction Time Conversion Selectivity/ Entry Catalyst code (h) (%) valerolactone 1 2 wt % Pt-HT 2 34 >99% 2 2 wt % Pt-HT 5 45 >99% 3 2 wt % Pt-HT 8 57 >99% 4 2 wt % Pt-HT 12 66 >99% 5 2 wt % Pt-HT 22 75 >99% 6 2 wt % Pt-HT 24 81 >99% 7 2 wt % Pt-HT 30 83 >99% 8 2 wt % Pt-HT 35 85 >99% 9 2 wt % Pt-HT 47 86 >99% 10 2 wt % Pt-HT 60 89 >99% 11 2 wt % Pt-HT 75 90 >99% 12 2 wt % Pt-HT 100 90 >99%

Example: 5

[0057] The hydroltalcite support was prepared by co-precipitation method. The procedure as follows: Salt solution A (100 ml) containing mixture of 0.080 mole Al(NO.sub.3).sub.3.9H.sub.2O and 0.020 mole Mg(N03).sub.26H.sub.20 was added drop wise to a basic solution of B (100 ml) containing 0.05 mole Na.sub.2CO.sub.3 and 0.17 mole NaOH. The pH was maintained between 9-13 and the mixture was aged for 1 h at room temperature with continuous stirring. Later temperature was raised to 80 C. and continued for 16 to 18 h. The resulted solid was washed with deionised water and dried at 110 C. in an oven for 12 h.

[0058] The Pt was deposited by wetness impregnation method. In a typical procedure, a 20 ml solution of 0.2 g of tetramine platinum nitrate nano hydrate (Pt(NH.sub.3).sub.4(NO.sub.3).sub.2) (2% on Pt basis) was mixed with 5 g of prepared hydrotalcite support stirred at room temperature for 1 h. The mixture was later dried at 60-80 C. at a duration of 2 to 4 h. The resulted solid was dried in an air oven at 110 C. for 12 h and calcined at 550 C. for 6 h.

[0059] Hydrogenation reactions were conducted in batch mode, in a 160 ml stainless steel autoclave (parr reactor) at various temperatures. leuvlicnic acid (5%), catalyst 0.2 g (reduced in H.sub.2 at 480 C.) and water (20 ml) were placed inside the reactor, after which the reactor was closed. Then the system was purged with hydrogen 4 times to remove the air. The whole system was pressurized to 20-50 bar hydrogen pressure and carried hydrogenation reaction at room temperature (25 C.) for 24 h. At the end of the reaction, the pressure was released very slowly. The catalyst particles were separated by filtration and the product was analyzed by an Agilent 7890 gas chromatograph equipped with a FID (using restek MXT WAX capillary Column 30 m0.25ID) using reference samples.

[0060] This example describes the effect of H.sub.2 pressure on conversion of leuvlicnic acid. The analysis results are presented in Table 4

TABLE-US-00004 TABLE 4 Hydrogen pressure Conversion Selectivity/ Entry Sample code (bar) (%) valerolactone 1 2 wt % Pt-HT 20 65 >99% 2 2 wt % Pt-HT 30 72 >99% 3 2 wt % Pt-HT 40 74 >99% 4 2 wt % Pt-HT 50 81 >99%

Example: 6

[0061] The hydroltalcite support was prepared by co-precipitation method. Salt solution A (100 ml) containing mixture of 0.080 mole Al(NO.sub.3).sub.3.9H.sub.2O and 0.020 mole Mg(NO.sub.3).sub.26H.sub.20 was added drop wise to a basic solution of B (100 ml) containing 0.05 mole Na.sub.2CO.sub.3 and 0.17 mole NaOH. The pH was maintained between 9-13 and the mixture was aged for 1 h at room temperature with continuous stirring. Later temperature was raised to 80 C. and continued for 16 to 18 h. The resulted solid was washed with deionised water and dried at 110 C. in an oven for 12 h.

[0062] The Pt was deposited by wetness impregnation method. In a typical procedure a 20 ml solution of 0.2 g of tetramine platinum nitrate nano hydrate (Pt(NH.sub.3).sub.4(NO.sub.3).sub.2) (3% on Pt basis) was mixed with 5 g of prepared hydrotalcite support stirred at room temperature for 1 h. The mixture was later dried at 60-80 C. at a duration of 2 to 4 h. The resulted solid was dried in an air oven at 110 C. for 12 h and calcined at 550 C. for 6 h.

[0063] Hydrogenation reactions were conducted in batch mode, in a 160 ml stainless steel autoclave (parr reactor) at various temperatures. leuvlicnic acid (5%), catalyst 0.2 g (reduced in H.sub.2 at 480 C.) and water (20 ml) were placed inside the reactor, after which the reactor was closed. Then the system was purged with hydrogen 4 times to remove the air. The whole system was pressurized to 50 bar hydrogen pressure and carried hydrogenation reaction between 25 to 75 C. for 5 h. At the end of the reaction, the pressure was released very slowly. The catalyst particles were separated by filtration and the product was analyzed by an Agilent 7890 gas chromatograph equipped with a FID (using restek MXT WAX capillary Column 30 m0.25ID) using reference samples.

[0064] This example describes the effect of reaction temperature on conversion of Leuvlinic acid. The analysis results are presented in Table 5

TABLE-US-00005 TABLE 5 Reaction Conversion Selectivity/ Entry Catalyst code temperature ( C.) (%) valerolactone 1 2 wt % Pt-HT 25 45 >99% 2 2 wt % Pt-HT 40 62 >99% 3 2 wt % Pt-HT 50 79 >99% 4 2 wt % Pt-HT 75 100 >99%

ADVANTAGES OF THE INVENTION

[0065] The main advantages of the present invention are: [0066] 1. The process of the present invention converts levulinic acid to -valerolactone in a single step with a single catalyst. [0067] 2. The process of the present invention hydrogenation of levulinic acid at room temperature. [0068] 3. The process shows conversion of levulinic acid up to 900/%. [0069] 4. The process provides selectivity of -valerolactone up to >99%. [0070] 5. The process provides good conversion even at low hydrogen pressure. [0071] 6. The catalyst is used in very low amounts. [0072] 7. The process does not produce any major by-products which is also a major advantage of the process.