USE OF RHENIUM-CONTAINING SUPPORTED HETEROGENOUS CATALYSTS FOR THE DIRECT DEOXY-DEHYDRATED OF GLYCEROL TO ALLYL ALCOHOL

Abstract

The present invention relates to the use of rhenium-containing supported heterogeneous catalysts for the deoxydehydration of glycerol to allyl alcohol, as well as to a process for the production of allyl alcohol from glycerol, in the presence of such heterogeneous catalysts.

Claims

1. A method for catalysing the deoxydehydration of glycerol to allyl alcohol, said method comprising: deoxydehydrating glycerol to allyl alcohol with an alumina-supported rhenium-oxide catalyst of formula ReO.sub.3/Al.sub.2O.sub.3 (I), wherein said reaction is carried out in heterogeneous conditions in the presence of at least one aliphatic alcohol.

2. The method of claim 1, wherein said at least one aliphatic alcohol is used as a solvent.

3. The method of claim 1, wherein said catalyst of formula (I) is chosen among those in which the amount of ReO.sub.3 ranges from 5 to 15 weight % relative to the total mass of catalyst of formula (I).

4. A process for the production of allyl alcohol from glycerol in the presence of a catalyst, said process comprising only one step of deoxydehydration of glycerol, said reaction being carried out in heterogeneous conditions, in the presence of i) an alumina-supported rhenium-oxide catalyst of formula ReO.sub.3/Al.sub.2O.sub.3 (I) and of ii) at least one aliphatic alcohol.

5. The process of claim 4, wherein the catalyst of formula (I) is chosen among catalysts in which the amount of ReO.sub.3 ranges from 5 to 15 weight % relative to the total amount of catalyst of formula (I).

6. The process of claim 4, wherein the aliphatic alcohol is a monohydroxylated alcohol having from 6 to 10 carbon atoms.

7. The process of claim 6, wherein the aliphatic alcohol is a monohydroxylated alcohol having from 6 to 8 carbon atoms.

8. The process of claim 7, wherein the monohydroxylated alcohol is a secondary alcohol.

9. The process according to claim 8, wherein the secondary alcohol is 2-hexanol or 3-octanol.

10. The process according to claim 3, wherein the deoxydehydration reaction is carried out at a temperature higher than or equal to 140 C.

11. The process according to claim 3, wherein the deoxydehydration reaction is carried out at a temperature ranging from 140 to 150 C.

Description

EXAMPLES

[0029] In the next examples, the following starting materials were used: [0030] Glycerol, purity in water >99% (Aldrich) [0031] Alumina (-Al.sub.2O.sub.3) having a surface area of 198.7 m.sup.2/g (B.E.T.) (Puralox), [0032] Silicium dioxide (SiO.sub.2) having a surface area of 105.5 m.sup.2/g (B.E.T.) (Fuji Silysia), [0033] Titanium oxide (TiO.sub.2) having a surface area of 62.5 m.sup.2/g (B.E.T.) commercialized under the name P25 (Aldrich, 99% purity), [0034] 75 w % perrhenic acid (HReO.sub.4) aqueous solution (Aldrich), [0035] 1-hexanol (Aldrich), [0036] 2-hexanol (Aldrich), [0037] 1-octanol (Aldrich), [0038] 3-octanol (Aldrich, [0039] 2-butanol (Aldrich), [0040] Cyclohexanol (Aldrich), [0041] 1-phenylethanol (Aldrich), [0042] Benzyl alcohol (Aldrich).

[0043] All these materials were used as received from the suppliers, i.e., without any additional purification.

Preparation of Alumina-Supported Rhenium Oxide Catalysts of Formula (I) According to the Invention

[0044] The different catalysts of formula (I) were prepared by an incipient-wetness impregnation method.

[0045] Catalysts of formula (I) containing respectively 5, 10 or 15 wt % of ReO.sub.3 relative to the total amount of catalysts were prepared. These catalysts were respectively denoted 5w %-ReO.sub.3/Al.sub.2O.sub.3, 10w %-ReO.sub.3/Al.sub.2O.sub.3, and 15 w %-ReO.sub.3/Al.sub.2O.sub.3.

[0046] For the preparation of 5 w %-ReO.sub.3/Al.sub.2O.sub.3, 1.81 g of -Al.sub.2O.sub.3 were added to a diluted aqueous solution of HReO.sub.4 resulting from the addition of 136 mg of the 75 w % perrhenic acid aqueous solution (Aldrich) in 1 mL of water.

[0047] For the preparation of 10 w %-ReO.sub.3/Al.sub.2O.sub.3, 1.81 g of -Al.sub.2O.sub.3 were added to a diluted aqueous solution of HReO.sub.4 resulting from the addition of 286 mg of the 75 w % perrhenic acid aqueous solution (Aldrich) in 1 mL of water.

[0048] For the preparation of 15 w %-ReO.sub.3/Al.sub.2O.sub.3, 1.81 g of -Al.sub.2O.sub.3 were added to a diluted aqueous solution of HReO.sub.4 resulting from the addition of 456 mg of the 75 w % perrhenic acid aqueous solution (Aldrich) in 1 mL of water.

[0049] After one hour, the impregnated catalysts were dried at 110 C. for 24 hours and calcinated under static air at 500 C. for 3 hours before their use in the catalytic tests.

Preparation of a TiO.SUB.2.-Supported Rhenium Oxide Comparative Catalyst Not Forming Part of the Present Invention

[0050] The same procedure as that described above for the preparation of catalysts of formula (I) has been used to prepare the comparative catalyst except that TiO.sub.2 (1.81 g) was used instead of Al.sub.2O.sub.3.

[0051] After one hour, the as-obtained impregnated catalyst (denoted 5-w %-ReO.sub.3/TiO.sub.2) was dried at 110 C. for 24 hours and calcinated under static air at 500 C. for 3 hours before its use in the catalytic tests.

Example 1: Conversion of Glycerol to Allyl Alcohol Using 10-Wt % ReO.SUB.3./Al.SUB.2.O.SUB.3 .(First/Second and Third Uses of the Catalyst)

[0052] First Use:

[0053] A pressure-resistant glass tube equipped with a magnetic stirring bar was loaded with glycerol (92 mg, 1 mmol), 10-wt % ReO.sub.3/AL.sub.2O.sub.3 (100 mg), and 2-hexanol (3.3 mL). The vessel was tightly sealed by a screw cap and the mixture was stirred (500 rpm) in an oil bath maintained at 170 C. for 2.5 h so that the reaction medium was maintained at a reaction temperature of 148 C. After reaction, the solution was cooled to room temperature and then diluted with 15 mL of methanol Biphenyl (20 mg, 0.13 mmol) was added to the solution as an internal standard for gas chromatography (GC) analysis. The solution was placed under ultrasonic irradiation for 10 min to assure a good homogeneity of the mixture. The conversion and yield were determined on the basis of the analysis of the mixture by GC.

[0054] The yield in allyl alcohol was 91%, the conversion of glycerol was >99%, and the selectivity to allyl alcohol (yield/conversion100) was 91% (first use).

[0055] Second Use:

[0056] The reaction proceeded as above for the first use, using the spent 10-wt %-ReO.sub.3/Al.sub.2O.sub.3 catalyst (82 mg) recovered from experiment 1 with a new amount of glycerol (75 mg) to keep the glycerol/catalyst ratio constant at the beginning of the reaction compared to the conditions of experiment 1 (first use).

[0057] The used 10-wt %-ReO.sub.3/Al.sub.2O.sub.3 was re-calcined at 500 C. for 3 h before the second reaction. The yield in allyl alcohol was 93%, the conversion of glycerol was >99%, and the selectivity to allyl alcohol was 93%.

[0058] Another test was also performed using the spent 10-wt %-ReO.sub.3/Al.sub.2O.sub.3 catalyst (82 mg) from experiment 1 (first use) with a new amount of glycerol (75 mg) but instead of carrying out calcination before the second use, only a drying at 110 C. was performed for 2 hours. The yield in allyl alcohol was 90%, the conversion of glycerol was >99%, and the selectivity to allyl alcohol was 90%. This additional result demonstrates that, even if a calcination step is preferably carried out before the reuse of the catalyst, such a calcination step is not compulsory at all to obtain good performances.

[0059] Third Use:

[0060] The reaction proceeded as described above for the second use, using the spent 10-wt %-ReO.sub.3/Al.sub.2O.sub.3 catalyst (62 mg) recovered from experiment 2 (with calcination) with a new amount of glycerol (62 mg) to keep the glycerol/catalyst ratio as a constant at the beginning of the reaction compared to the conditions of experiment 1.

[0061] The used 10-wt %-ReO.sub.3/Al.sub.2O.sub.3 was again re-calcined at 500 C. for 3 h before the third reaction.

[0062] The yield in allyl alcohol was 92%, the conversion of glycerol was >99%, and the selectivity to allyl alcohol was 92%.

[0063] These results demonstrate that the catalyst of formula (I) can be easily reused to give allyl alcohol with 93% or 92% yields, respectively, for the second and third uses. No peak assigned to acrolein or acrylic acid was observed in .sup.1H NMR analysis of the products.

Example 2: Conversion of Glycerol to Allyl Alcohol Using 5-wt %-ReO.SUB.3./Al.SUB.2.O, 10-wt %-ReO.SUB.3./Al.SUB.2.O.SUB.3 .and 15-wt %-ReO.SUB.3./Al.SUB.2.O.SUB.3

[0064] The conversion of glycerol to allyl alcohol has been performed in the same conditions as those described in example 1 above (first use).

[0065] The results obtained with over of the catalysts of formula (I) are given in Table 1 below:

TABLE-US-00001 TABLE 1 Allyl alcohol Glycerol Allyl alcohol Catalyst (I) Yield (%) Conversion (%) Selectivity (%) 5-wt%-ReO.sub.3/Al.sub.2O.sub.3 77 >99 77 10-wt%-ReO.sub.3/Al.sub.2O.sub.3 91 >99 91 15-wt%-ReO.sub.3/Al.sub.2O.sub.3 88 >99 88

Example 3: Conversion of Glycerol to Allyl Alcohol Using 5-wt %-ReO.SUB.3./Al.SUB.2.O.SUB.3.Comparison with 5-wt %-ReO.SUB.3./TiO.SUB.2

[0066] In this example, the conversion performances of the 5-w %-ReO.sub.3/Al.sub.2O.sub.3 of formula (I) according to the present invention were compared to that of a catalyst not being part of the present invention, namely 5-w %-ReO.sub.3/TiO.sub.2.

[0067] The conversion of glycerol to allyl alcohol was carried in the same conditions as those used in example 1, first use, unless otherwise stated.

[0068] The results are given in the following Table 2:

TABLE-US-00002 TABLE 2 Allyl alcohol Glycerol Allyl alcohol Catalyst Yield (%) Conversion (%) Selectivity (%) 5-wt%-ReO.sub.3/Al.sub.2O.sub.3 77 >99 77 5-wt%-ReO.sub.3/TiO.sub.2 .sup.(*) 82 >99 82 .sup.(*) Comparative catalyst not forming part of the invention

[0069] As shown in Table 2, TiO.sub.2 and Al.sub.2O.sub.3 supports showed high reactivity (82% and 77% yields to allyl alcohol for TiO.sub.2 and Al.sub.2O.sub.3, respectively). While TiO.sub.2 showed higher reactivity than Al.sub.2O.sub.3, it was not possible to reuse the ReO.sub.3/TiO.sub.2 catalyst because of rhenium leaching from the TiO.sub.2 support.

Example 4: Conversion of Glycerol to Allyl Alcohol Using 10-wt %-Re.SUB.3./Al.SUB.2.O.SUB.3 .at Different Temperatures

[0070] In this example, the conversion of glycerol to allyl alcohol was carried out using the same conditions as those in example 1 above, first use, but varying the temperature of the oil bath, so that the temperature of the reaction medium also varied.

[0071] The results are given in Table 3 below:

TABLE-US-00003 TABLE 3 Allyl Oil Bath Reaction Allyl Glycerol alcohol temperature temperature alcohol Conversion Selectivity Example ( C.) ( C.) Yield (%) (%) (%) 4a 150 140 75 89 84 4b 170 148 91 >99 91 4c 180 148 90 >99 90

[0072] Although 2-hexanol has, at atmospheric pressure, a boiling point (b.p.) of 139 C., the preferred reaction temperature is higher than 139 C.

[0073] The reaction with the same catalysts at a temperature of the oil bath of 150 C. (observed inner reaction temperature: 140 C.) gave allyl alcohol with a 75% yield. When the temperature of the oil bath was 170 C. (observed inner reaction temperature: 148 C.), allyl alcohol was obtained in excellent yield (91%).

Example 5: Conversion of Glycerol to Allyl Alcohol Using 10-wt %-ReO.SUB.3./Al.SUB.2.O.SUB.3 .in Aliphatic Alcohol SolventsComparison with Cyclic Alcohol Solvents

[0074] In this example, the conversion of glycerol to allyl alcohol was carried out in the same conditions as those of example 1 (first use) but using different aliphatic alcohols according to the process of the invention, and in comparison with some cyclic alcohols according to a process not forming part of the present invention.

[0075] The results are tabulated in Table 4 below:

TABLE-US-00004 TABLE 4 Allyl alcohol Glycerol Allyl alcohol Alcohol Yield (%) Conversion (%) Selectivity (%) 2-hexanol 91 >99 91 1-hexanol 73 >99 73 1-octanol 45 93 48 3-octanol 84 93 90 2-butanol 40 51 78 Cyclohexanol .sup.(*) 30 52 58 1-phenylethanol .sup.(*) 0 83 0 Benzyl alcohol .sup.(*) 8 85 9 .sup.(*) Comparative catalyst not forming part of the invention

[0076] These results show that all the aliphatic alcohols used as solvents according to the process of the present invention lead to allyl alcohol with a yield of at least 40%. However, among these alcohols, and for the same number of carbon atoms, secondary alcohols showed higher yields than primary alcohols. On the contrary, the use of cyclohexanol induced a yield lower than 40% and aryl alcohols (1-phenylethanol and benzyl alcohol) are not acceptable solvents of the deoxydehydration of glycerol to allyl alcohol in the presence of a catalyst of formula (I) since the yields were very low despite high conversions (0% and 8% yields when using 1-phenylethanol and benzyl alcohol, respectively).

Example 6: Conversion of Glycerol to Allyl Alcohol Using 10-wt %-ReO.SUB.3./Al.SUB.2.O.SUB.3 .Using Glycerol Exhibiting Different Fractions of Water

[0077] In this example, the conversion of glycerol to allyl alcohol was carried out in 2-hexanol with 10-wt %-ReO.sub.3/Al.sub.2O.sub.3 using glycerol containing different fractions of water, i.e., containing from less than 1 wt % to 20 wt % of water.

[0078] The glycerol solutions with different degrees of purity in water were simply prepared by adding the required amounts of water in purchased glycerol having a purity of >99%.

[0079] The corresponding results are tabulated in Table 5 below:

TABLE-US-00005 TABLE 5 Purity of Amount of Glycerol Glycerol in added water Allyl alcohol Conversion Allyl alcohol water (wt %) (wt %) Yield (%) (%) Selectivity (%) >99 0 91 >99 91 95 5 91 >99 91 85 16 80 93 86 80 23 66 93 71

[0080] These results show that the process of deoxydehydration of glycerol according to the present invention can be carried out with very good yield in allyl alcohol even if the glycerol exhibit a purity in water of only 80 wt %.