SYNTHESIS OF SAPO-18 AND THE CATALYTIC APPLICATIONS THEREOF

Abstract

Synthesis of the silicoaluminophosphate and metal silicoaluminophosphate polymorphs of the molecular sieve SAPO-18 using cyclic quaternary ammoniums as organic structure-directing agents (OSDA) and use thereof as a catalyst.

Claims

1. A procedure for the synthesis of SAPO-18 comprising the following steps: i) preparing a mixture containing at least water, at least one source of silicon, at least one source of aluminium, at least one source of phosphorus, one or more; organic structure-directing agents (OSDA), wherein at least one OSDA is a cyclic quaternary ammonium, and where the mixture has the following molar composition:
a Si:0.5Al:b P:c OSDA:d H.sub.2O where a is between the interval 0.01 to 0.3; where b is between the interval 0.2 to 0.49; where c is between the interval 0.001 to 2; where d is between the interval 1 to 200. ii) hydrothermally treating the mixture at a temperature between 80-200° C. until a crystalline material is formed, and iii) recovering the crystalline material.

2. The procedure of claim 1, wherein the mixture has the following molar composition:
a Si:0.5Al:b P: c OSDA:d H.sub.2O where a is between the interval 0.03 to 0.3; where b is between the interval 0.2 to 0.47; where c is between the interval. 0.1 to 1; where d is between the interval 2 to 200.

3. The procedure to claim 1, wherein the cyclic quaternary ammonium is selected from the group consisting of N,N-dimethyl-3,5-dimethylpiperidine (DMDMP), N,N-diethyl-2,6-dimethylpiperidine (DEDMP), N,N-dimethyl-2,6-dimethylpiperidine, N-ethyl-N-methyl-2,6-dimethylpiperidine and combinations thereof.

4. (canceled)

5. The procedure of claim 1, wherein step (ii) is carried out in an autoclave under both static and dynamic conditions.

6. The procedure of claim 1, wherein the temperature of step (ii) is within the temperature range of 100 and 200° C.

7. The procedure of claim 1, in step (ii) the mixture is hydrothermally treated between 1 hour and 50 days.

8. The procedure of claim 1, wherein crystals of the SAPO-18 material are added to the mixture as seed after step (i) but before step (ii).

9. The procedure of claim 8, wherein the amount of SAPO-18 crystals is up to 25% by weight of the total components introduced in the synthesis.

10. The procedure of claim 1, wherein in step (iii) the crystalline material is separated from a mother liquor by decantation, filtration, ultrafiltration, centrifugation, a solid-liquid separation technique and combinations thereof.

11. The procedure of claim 1, further comprising removing an organic matter occluded in the interior of the material.

12. The procedure of claim 11, wherein the removal of the organic matter is carried by extraction, thermal treatment or combinations thereof and at a temperature above 25° C. between 2 minutes and 25 hours.

13. The procedure of claim 1, wherein the crystalline material is pelletized.

14. The procedure of claim 1, wherein the mixture further comprises, at least one source of metal where the mixture has the following molar composition:
a Si:0.5Al:b P:e X:c OSDA:d H.sub.2O where a is between the interval 0.01 to 0.3; where b is between the interval 0.2 to 0.49; where c is between the interval. 0.001 to 2; where d is between the interval 1 to 200; where e is between the interval 0.00 to 0.6.

15. The procedure of claim 14, the procedure is a direct synthesis procedure and the product Me-SAPO-18 is obtained, wherein Me is a metal.

16. The procedure of claim 15, wherein said metal is selected from the group consisting of Cu, Ni, Fe, Pt, Pd, Mn, Ca, Mg, Zn, Cd, Co, Ti, Sn and combinations thereof.

17. The procedure of claim 16, wherein said metal is Cu.

18. A product obtained by the procedure of claim 1, wherein the product has the following molar composition:
X.sub.0.0-0.6Si.sub.0.01-0.3Al.sub.0.40-0.55P.sub.0.20-0.49O.sub.2

19. The product claim 18, wherein the product has the following molar composition:
X.sub.0.005-0.6Si.sub.0.01-0.3Al.sub.0.40-0.55P.sub.0.20-0.49O.sub.2

20. The product of claim 19, wherein X is a metal selected from the group consisting of Cu, Ni, Fe, Pt, Pd, Mn, Ca, Mg, Zn, Cd, Co, Ti, Sn and combinations thereof.

21. The product of claim 20, said metal is Cu.

22. The product of claim 20, wherein the metal is in extra-network positions.

23. (canceled)

24. A catalyst for the removal or separation of organic compounds from the reactive current comprising the product of claim 18.

25. (canceled)

26. A catalyst for converting feed formed by organic compounds into high value-added products comprising the product of claim 18.

27. A catalyst for the selective reduction of nitrogen oxides in a gas stream, wherein the catalyst comprises the product of claim 18.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0041] FIG. 1: X-ray diffraction patterns of the solid synthesized in examples 3 and 6 described herein.

[0042] FIG. 2: Solid .sup.295i Nuclear magnetic resonance (NMR) spectra of synthesized samples according to Examples 3 and 6.

[0043] FIG. 3: UV-Vis spectra of the sample synthesized in Example 6 of the present invention in its uncalcinated form and of the Cu-TETA complex in an aqueous solution.

EXAMPLES

[0044] The following examples are provided by way of illustration and are not intended to be limiting of the present invention.

Example 1

Synthesis of OSDA iodide N,N-dimethyl-3,5-dimethylpiperidine (DMDMP)

[0045] 10 g of 3,5-dimethylpiperidine (Sigma-Aldrich, ≧96% by weight) are mixed with 19.51 g of potassium bicarbonate (KHCO.sub.3 Sigma-Aldrich; 99.7% by weight) and dissolved in 140 ml of methanol. Next, 54 ml of methyl iodide (CH.sub.3I, Sigma-Aldrich, ≧99% by weight) are added and the resulting mixture is kept under stirring for 5 days at room temperature. After this time, the reactive mixture was filtered to remove the potassium bicarbonate. The filtered solution is partially concentrated by rotary evaporation. Once the methanol has been partially evaporated, the solution is washed several times with chloroform and magnesium sulphate (MgSO.sub.4 Sigma-Aldrich, ≧99.5% by weight) is added. The mixture is filtered to remove the magnesium sulphate. Ammonium salt is obtained by precipitation with diethyl ether and subsequent filtration. The final yield of iodide N,N-dimethyl-3,5-dimethylpiperidine is 85%.

[0046] To prepare the hydroxide form of the above organic salt: 10.13 g of the organic salt are dissolved in 75.3 g of water. Next, they are added with 37.6 g of an anion exchange resin (Dower SBR) and the resulting mixture is kept under stirring for 24 hours. Finally, the solution is filtered and N,N-dimethyl-3,5-dimethylpiperidine hydroxide is obtained (with an exchange percentage of 94%).

Example 2

Synthesis of OSDA iodide N,N-diethyl-2,6-dimethylpiperidine (DEDMP)

[0047] 36 g of cis-2,6-dimethylpiperidine (Sigma-Aldrich, 98% by weight) are mixed with 320 ml of methanol and 64 g of potassium bicarbonate (KHCO.sub.3 Sigma-Aldrich; 99.7% by weight). Subsequently, 200 g of ethyl iodide (Sigma-Aldrich, 99% by weight) are added and the resulting mixture is refluxed for 5 days. After this time, the reaction mixture is filtered to remove potassium bicarbonate. The filtered solution is partially concentrated by rotary evaporation. Once the methanol is partially evaporated, the solution is washed several times with chloroform and added with magnesium sulphate (MgSO.sub.4 Sigma-Aldrich, ≧99.5% by weight). The mixture is filtered to remove the magnesium sulphate. Ammonium salt is obtained by precipitation with diethyl ether and subsequent filtration. The final yield of N,N-diethyl-2,6-dimethylpiperidine iodide is 75%.

[0048] To prepare the hydroxide form of the above organic salt: 10 g of organic salt is dissolved in 75 g of water. Next, 40 g of an anion exchange resin (Dower SBR) are added and the resulting mixture is kept under stirring for 24 hours. Finally, the solution is filtered and the N,N-diethyl-2,6-dimethylpiperidine hydroxide (with a percentage of 90% exchange) is obtained.

Example 3

Synthesis of the SAPO-18 material using DMDMP as OSDA

[0049] First, 1324.3 mg of orthophosphoric acid (85% by weight, Aldrich) is mixed with 6287.0 mg of an aqueous solution at 19% by weight of DMDMP hydroxide and kept under stirring for 10 minutes. Next, 1043.8 mg of alumina (75% by weight, Condea) and 304.2 mg of a colloidal silica suspension (Ludox AS40 40% by weight, Aldrich) are introduced. The resulting mixture is kept under stirring for the required time to evaporate the excess of water to achieve the desired gel concentration. The final composition of the gel is:

0.066SiO.sub.2:0.19P.sub.2O.sub.5:0.25Al.sub.2O.sub.3:0.24DMDMP:4.6H.sub.2O

[0050] The gel is transferred to a Teflon-lined autoclave, and heated at 190° C. for 2 days under dynamic conditions. After the hydrothermal crystallization process, the sample is filtered and washed with abundant distilled water and finally dried at 100° C.

[0051] The sample is characterised by X-ray diffraction (XRD), observing the formation of the characteristic XRD pattern of SAPO-18 (see FIG. 1).

[0052] As evidenced by the solid .sup.29Si nuclear magnetic resonance (NMR), the synthesized SAPO-18 shows only the presence of isolated silicon species in its structure (see the band centred at −90 ppm in the sample Example 3 in FIG. 2).

[0053] The sample is calcinated at 550° C. in air to remove the organic matter fractions occluded in the interior of the microporous material during the crystallization process.

Example 4

Synthesis of SAPO-18 Material using DMDMP as OSDA

[0054] First, 1365.3 mg of orthophosphoric acid (85 wt %, Aldrich) is mixed with 6282.0 mg of an aqueous solution at 19% by weight of DMDMP hydroxide and kept under stirring for 10 minutes. Next, 1016.3 mg of alumina (75% by weight, Condea) and 195.3 mg of a colloidal silica suspension (Ludox AS40 40% by weight, Aldrich) are introduced. The resulting mixture is kept under stirring for the required time to evaporate the excess of water to achieve the desired gel concentration. The final composition of the gel is:

0.043SiO.sub.2:0.20P.sub.2O.sub.5:0.25Al.sub.2O.sub.3:0.25DMDMP:4.8H.sub.2O

[0055] The gel is transferred to a Teflon-lined autoclave and heated at 190° C. for 2 days under dynamic conditions. After the hydrothermal crystallization process, the sample is filtered and washed with abundant distilled water and finally dried at 100° C.

[0056] The sample is characterised by X-ray diffraction to determine the structure obtained after the crystallization process, observing the characteristic diffraction pattern of SAPO-18.

[0057] The sample is calcinated at 550° C. in air to remove organic matter fractions occluded in the interior of the microporous material during the crystallization process.

Example 5

Synthesis of SAPO-18 Material using DEDMP as OSDA

[0058] First 107.5 mg of orthophosphoric acid (85 wt %, Aldrich) is mixed with 712.2 mg of an aqueous solution at 15% by weight of DEDMP hydroxide and kept under stirring for 10 minutes. Next, 83.5 mg of alumina (75% by weight, Condea) and 17.9 mg of a colloidal silica suspension (Ludox AS40 40% by weight, Aldrich) are introduced. The resulting mixture is kept under stirring for the required time to evaporate the excess of water until the gel reaches the desired concentration of the gel. The final composition of the gel is:

0.048SiO.sub.2:0.19P.sub.2O.sub.5:0.25Al.sub.2O.sub.3:0.23DEDMP:5.0H.sub.2O

[0059] The gel is transferred to a Teflon-lined autoclave, and heated at 190° C. for two days under dynamic conditions. After the hydrothermal crystallization process, the sample is filtered and washed with abundant distilled water and finally dried at 100° C.

[0060] The sample is characterised by X-ray diffraction to determine the structure obtained after the crystallization process, observing the characteristic diffraction pattern of SAPO-18.

[0061] The sample is calcinated at 550° C. in air to remove organic matter fractions occluded in the interior of the microporous material during the crystallization process.

Example 6

Direct Synthesis of the Cu-SAPO-18 Material using Cu Triethylenetetramine (Cu-TETA) as a Precursor of Cu and DMDMP as OSDA

[0062] The first step is the preparation of the Cu-TETA copper complex. To this end, 405.9 mg of a 20% aqueous solution by weight of copper sulphate (II) (98% by weight, Alfa) is mixed with 74.5 mg of triethylenetetramine (TETA, 99% by weight, Aldrich) and kept under stirring for 2 hours. Next, 2700 mg of distilled water and 1035.8 mg of orthophosphoric acid (85% by weight, Aldrich) are added and the resulting solution is kept under stirring for 5 minutes. Finally, 8840 mg of an aqueous solution at 17.1% by weight of DMDMP hydroxide is added, and kept under stirring another 5 minutes. Finally, 734.7 mg of alumina (75% by weight, Condea) and 241.5 mg of a colloidal silica suspension (Ludox AS40 40% by weight, Aldrich) are introduced. The resulting mixture is stirred for 30 minutes or the required time to evaporate the excess of water to achieve the desired gel concentration. The final composition of the gel is:

0.074SiO.sub.2:0.21P.sub.2O.sub.5:0.25Al.sub.2O.sub.3:0.023Cu-TETA:0.44DMDMP:27.8H.sub.2O

[0063] The gel is transferred to a Teflon-lined autoclave, and heated at 175° C. for 6 days under dynamic conditions. After the hydrothermal crystallization process, the sample is filtered and washed with abundant distilled water and finally dried at 100° C.

[0064] The sample was characterised by X-ray diffraction to determine the structure obtained after the crystallization process (see the XRD pattern in FIG. 1).

[0065] The as-prepared sample is characterised by ultraviolet-visible (UV-Vis) spectroscopy to verify that the copper atoms are in extra-network positions. The UV-Vis spectrum of the sample in its uncalcinated form shows a single band centred at ˜260 nm, which shows the presence of the intact organometallic complex within the solid in extra-framework positions (see FIG. 3).

[0066] As shown by the solid .sup.29Si nuclear magnetic resonance (NMR) spectrum, the synthesized SAPO-18 only shows the presence of isolated silicon species in its structure (see the band centred at −90 ppm in the sample Example 6 in FIG. 2).

[0067] The sample is calcinated at 550° C. in air to remove the organic matter fractions occluded in the interior of the microporous material during the crystallization process.

Example 7

Direct Synthesis of the Cu-SAPO-18 Material using Cu Triethylenetetramine (Cu-TETA) as a Precursor of Cu and DMDMP as OSDA

[0068] The first step is the preparation of the Cu-TETA copper complex. To this end, 799.2 mg of a 20% aqueous solution by weight of copper sulphate (II) (98 wt %, Alfa) is mixed with 145.5 mg of triethylenetetramine (TETA, 99% by weight, Aldrich) and kept under stirring for 2 hours. Next, 2800 mg of distilled water and 1043.2 mg of orthophosphoric acid (85% by weight, Aldrich) are added and the resulting solution is kept under stirring for 5 minutes. Subsequently, 8405 mg of an aqueous solution at 17.1% by weight of DMDMP hydroxide is added and kept under stirring another 5 minutes. Finally, 734.5 mg of alumina (75% by weight, Condea) and 254.2 mg of a colloidal silica suspension (Ludox AS40 40% by weight, Aldrich) are introduced. The resulting mixture is stirred for 30 minutes or the required time to evaporate the excess of water to achieve the desired gel concentration. The final composition of the gel is:

0.078SiO.sub.2:0.21P.sub.2O.sub.5:0.25Al.sub.2O.sub.3:0.046Cu-TETA:0.42DMDMP:28.8H.sub.2O

[0069] The gel is transferred to a Teflon-lined autoclave and heated at 175° C. for 6 days under dynamic conditions. After the hydrothermal crystallization process, the sample is filtered and washed with abundant distilled water and finally dried at 100° C.

[0070] The sample is characterised by X-ray diffraction to determine the structure obtained after the crystallization process, observing the characteristic diffraction pattern of SAPO-18.

[0071] The sample is calcinated at 550° C. in air to remove the organic matter fractions occluded in the interior of the microporous material during the crystallization process.

Example 8

Direct Synthesis of the Cu-SAPO-18 Material using Cu-Triethylenetetramine (Cu-TETA) as a Precursor of Cu and DMDMP as OSDA

[0072] The first step is the preparation of the Cu-TETA copper complex. To do this, 1591.4 mg of a 20% aqueous solution by weight of copper sulphate (II) (98% by weight, Alfa) is mixed with 296.4 mg of triethylenetetramine (TETA, 99% by weight, Aldrich) and kept stirring for 2 hours. Next, 1056.0 mg of orthophosphoric acid (85% by weight, Aldrich) is added and the resulting solution is kept under stirring for 5 minutes. Subsequently, 10031 mg of an aqueous solution at 12.2% by weight of DMDMP hydroxide is added and is kept under stirring for another 5 minutes. Finally, 735.0 mg of alumina (75% by weight, Condea) and 242.1 mg of a colloidal silica suspension (Ludox AS40 40% by weight, Aldrich) are introduced. The resulting mixture is stirred for 30 minutes or the required time to evaporate the excess of water to achieve the desired gel concentration. The final composition of the gel is:

0.074SiO.sub.2:0.21P.sub.2O.sub.5:0.25Al.sub.2O.sub.3:0.093Cu-TETA:0.36DMDMP:29.3H.sub.2O

[0073] The gel is transferred to a Teflon-lined autoclave and heated at 175° C. for 6 days under dynamic conditions. After the hydrothermal crystallization process, the sample is filtered and washed with abundant distilled water and finally dried at 100° C.

[0074] The sample was characterised by X-ray diffraction to determine the structure obtained after the crystallization process, observing the characteristic diffraction pattern of SAPO-18.

[0075] The sample is calcinated at 550° C. in air to remove the organic matter fractions occluded in the interior of the microporous material during the crystallization process.

Example 9

Direct Synthesis of Cu-SAPO-18 Material using Cu-Triethylenetetramine (Cu-TETA) as Precursor of Cu and DMDMP as OSDA

[0076] The first step is the preparation of the Cu-TETA copper complex. To this end, 400.8 mg of an aqueous solution 20% by weight of copper sulphate (II) (98% by weight, Alfa) with 72.9 mg of triethylenetetramine (TETA, 99% by weight, Aldrich) are added and kept under stirring for 2 hours. Next, 1076.8 mg of orthophosphoric acid (85% by weight, Aldrich) is added and the resulting solution is kept under stirring for 5 minutes. Subsequently, 8692 mg of an aqueous solution at 17.4% by weight of DMDMP hydroxide is added and kept under stirring for another 5 minutes. Finally, 734.5 mg (75% by weight, Condea) and 251.6 mg of a colloidal silica suspension (Ludox AS40 40% by weight, Aldrich) are introduced. The resulting mixture is kept under stirring for 30 minutes or the required timeto evaporate the excess of water to achieve the desired gel concentration. The final composition of the gel is:

0.077SiO.sub.2:0.21P.sub.2O.sub.5:0.25Al.sub.2O.sub.3:0.023Cu-TETA:0.44DMDMP:31.2H.sub.2O

[0077] The gel is transferred to a Teflon-lined autoclave, and heated at 190° C. for 3 days under dynamic conditions. After the hydrothermal crystallization process, the sample is filtered and washed with abundant distilled water and finally dried at 100° C.

[0078] The sample was characterised by X-ray diffraction to determine the structure obtained after the process, observing the characteristic diffraction pattern of SAPO-18.

[0079] The sample is calcinated at 550° C. in air to remove the organic matter fractions occluded in the interior of the microporous material during the crystallization process.

Example 10

Direct Synthesis of the Cu-SAPO-18 Material using Cu-Triethylenetetramine (Cu-TETA) as a Precursor of Cu and DMDMP as OSDA

[0080] The first step is the preparation of the Cu-TETA copper complex. To this end, 799.2 mg of an aqueous solution 20% by weight of copper sulphate (II) (98% by weight, Alfa) is mixed with 145.4 mg of triethylenetetramine (TETA, 99% by weight, Aldrich) and kept under stirring for 2 hours. Next, 1061.6 mg of orthophosphoric acid (85% by weight, Aldrich) is added and the resulting solution is kept under stirring for 5 minutes. Subsequently, 8244 mg of an aqueous solution at 17.4% by weight of DMDMP hydroxide is added and kept under stirring another 5 minutes. Finally, 735.4 mg of alumina (75% by weight, Condea) and 248.1 mg of a colloidal silica suspension (Ludox AS40 40% by weight, Aldrich) are introduced. The resulting mixture is stirred for 30 minutes or the required time to evaporate the excess of water to achieve the desired gel concentration. The final composition of the gel is:

0.076SiO.sub.2:0.21P.sub.2O.sub.5:0.25Al.sub.2O.sub.3:0.046Cu-TETA:0.42DMDMP:32.5H.sub.2O

[0081] The gel is transferred to a Teflon-lined autoclave, and heated at 190° C. for 3 days under dynamic conditions. After the hydrothermal crystallization process, the sample is filtered and washed with abundant distilled water and finally dried at 100° C.

[0082] The sample was characterized by X-ray diffraction to determine the structure obtained after the crystallization process, observing the characteristic diffraction pattern of SAPO-18.

[0083] The sample is calcinated at 550° C. in air to remove the organic matter fractions occluded in the interior of the microporous material during the crystallization process.

Example 11

Chemical Analysis of Various Cu-SAPO-18 Materials obtained herein

[0084] Molar ratios of Si and Cu obtained by ICP of the materials synthesized in examples 6, 7, 8, 9 and 10 (see Table 1).

TABLE-US-00001 TABLE 1 Molar ratios of solids synthesized according to Examples 7, 8 and 9 of the present invention. Example Si/(Al + P) Cu/(Al + P) 5 0.097 0.028 7 0.101 0.058 8 0.104 0.063 9 0.089 0.029 10 0.090 0.064

Example 12

Thermal Treatments in the Presence of Steam

[0085] The hydrothermal stability of some of the samples synthesized in the examples of the present invention is studied by treating them with steam (2.2 ml/min) at 750° C. for 13 hours.

Example 13

Catalytic Test for the SCR of NOx Reaction using Different Cu-SAPO-18 Materials Synthesized According to the Present Invention

[0086] The activity of these samples for the selective catalytic reduction of NOx is studied using a tubular fixed-bed quartz reactor 1.2 cm in diameter and 20 cm long. In a typical experiment, the catalyst is compacted into particles in the size range of 0.25 to 0.42 mm, which are introduced into the reactor, and the temperature is increased to 550° C. (see the reaction conditions in Table 2); subsequently, the temperature is maintained for 1 hour under nitrogen flow. Once the desired temperature has been reached, the reactive mixture is fed. The SCR of NOx is studied using NH.sub.3 as a reducing agent. The NOx present in the gases that flow out of the reactor is continuously analysed using a chemiluminescent detector (Thermo 62C).

TABLE-US-00002 TABLE 2 Reaction conditions of SCR of NOx. Total gas flow (ml/min) 300 Catalyst load (mg) 40 Concentration of NO (ppm) 500 Concentration of NH.sub.3 (ppm) 530 Concentration of O.sub.2 (%) 7 Concentration of H.sub.2O 5 Temperature interval tested (° C.) 170-550

[0087] The catalytic results of some of the catalysts synthesized in any of the examples of the present invention are summarised in Table 3. In Table 3, the catalytic results of the materials synthesized in examples 7, 9 and 10, after being treated with steam, are also described They are treated with steam at 750° C. for 13 hours (Example 7-750° C., Example 9-750° C. and 10-750° C., respectively).

TABLE-US-00003 TABLE 3 Conversion (%) of NOx at different temperatures (200, 250, 300, 350, 400, 450, 500° C.) using the various Cu-SAPO-18 materials synthesized following the synthesis methodology described herein. Conversion (%) of NOx at different temperatures 210° C. 250° C. 300° C. 350° C. 400° C. 450° C. 500° C. 550° C. Example 6 63.1 82.0 81.2 82.6 87.4 90.6 83.5 52.9 Example 7 79.0 93.5 94.1 94.3 94.3 91.9 78.2 54.9 Example 8 75.9 85.5 85.8 87.2 89.4 89.3 75.2 47.2 Example 7-750° C. 84.6 92.9 91.5 91.7 90 88.3 74.6 61.1 Example 9-750° C. 84.6 93.3 90.9 92.4 92.2 93.9 89.1 82.2 Example 10-750° C. 93.2 99 98.6 99.4 98.4 97.1 88.7 82.6