PROCESS AND CATALYST FOR THE PREPARATION OF ETHYLENE

Abstract

A process for the preparation of ethylene by the dehydration of ethanol in the presence of a zeolite catalyst having the MOR framework code, wherein the process is operated at a temperature in the range of from 100° C. to 300° C., for example from 140° C. to 270° C., such as from 150° C. to 250° C., and wherein the zeolite catalyst having the MOR framework code has been modified by the adsorption of an optionally substituted pyridine compound.

Claims

1. A process for the preparation of ethylene by the dehydration of ethanol in the presence of a zeolite catalyst having the MOR framework code, wherein the process is operated at a temperature in the range of from 100° C. to 300° C., and wherein the zeolite catalyst having the MOR framework code has been modified by the adsorption of an optionally substituted pyridine compound.

2. A process according to claim 1, wherein the process is operated in the vapour phase.

3. A process according to claim 1, wherein the optionally substituted pyridine compound is a compound of formula I: ##STR00002## wherein each of X.sup.1 to X.sup.5 are independently selected from hydrogen, hydroxy groups, optionally substituted hydrocarbyl groups, optionally substituted alkoxy groups, optionally substituted aromatic groups, or any two of X.sup.1 to X.sup.5 may be bonded together with an optionally substituted hydrocarbyl group or an optionally substituted alkoxy group to form a cyclic group.

4. A process according to claim 3, wherein each of X.sup.1 to X.sup.5 are independently selected from hydrogen, C.sub.1-C.sub.11 hydrocarbyl groups, and C.sub.1-C.sub.11 alkoxy groups.

5. A process according to claim 3, wherein one of the X.sup.1 to X.sup.5 groups is a group selected from C.sub.1-C.sub.11 hydrocarbyl groups, C.sub.1-C.sub.11 alkoxy groups, and the other the X.sup.1 to X.sup.5 groups are all hydrogen groups.

6. A process according to claim 1, wherein the optionally substituted pyridine compound is selected from pyridine, 2-methylpyridine, 3-methylpyridine, 4-methylpyridine, 2-ethylpyridine, 3-ethylpyridine, 4-ethylpyridine, 4-n-propylpyridine, 3-n-butylpyridine, 4-hydroxypyridine, 4-methoxypyridine, 4-ethoxypyridine, collidines, and lutidines.

7. A process according to claim 1, wherein the zeolite catalyst having the MOR framework code is mordenite.

8. A process according to claim 7, wherein the mordenite has been synthesised using an organic-structure directing agent (OSDA)

9. A process according to claim 1, wherein the zeolite catalyst having the MOR framework code is composited with a binder material.

10. A process according to claim 1, wherein the optionally substituted pyridine compound is adsorbed on to the zeolite catalyst having the MOR framework code by impregnation prior to using the catalyst in the dehydration process.

11. A process according to claim 1, wherein the optionally substituted pyridine compound is added as a component of the feed to the dehydration process.

12. A process according to claim 1, wherein at least part of any unconverted ethanol together with any diethyl ether and optionally the by-product water present in the product stream is separated from the ethylene product and recycled back to the dehydration process.

13. A process according to claim 1, wherein the ethanol feed to the dehydration process comprises at least 50% wt. ethanol.

14. A process according to claim 1, wherein the ethanol feed to the dehydration process comprises bioethanol.

15. A catalyst composition comprising a zeolite catalyst having the MOR framework code that has been modified by the adsorption of an optionally substituted pyridine compound.

16. A catalyst composition according to claim 15, wherein the zeolite catalyst having the MOR framework code is mordenite.

17. A catalyst composition according to claim 16, wherein the mordenite has been synthesised using an organic-structure directing agent (OSDA).

18. (canceled)

19. A method of preparing a catalyst composition, the method comprising, providing a catalyst having the MOR framework code, and modifying the zeolite catalyst by the adsorption of an optionally substituted pyridine compound.

20. The method of claim 19, the wherein the optionally substituted pyridine compound is a compound of formula I: ##STR00003## wherein each of X.sup.1 to X.sup.5 are independently selected from hydrogen, hydroxy groups, optionally substituted hydrocarbyl groups, optionally substituted alkoxy groups, optionally substituted aromatic groups, or any two of X.sup.1 to X.sup.5 may be bonded together with an optionally substituted hydrocarbyl group or an optionally substituted alkoxy group to form a cyclic group.

21. The method of claim 19, further comprising filtering the catalyst composition, washing and drying the catalyst composition.

Description

EXAMPLES

Preparation of Catalyst A

[0067] NH.sub.4-mordenite (CBV21A, Zeolyst International) was calcined in air at 500° C. for 4 hours to convert it into the H-form.

Preparation of Catalyst B

[0068] 2-ethylpyridine (0.14 mL) was dissolved in methanol (25 mL) before being added to Catalyst A (2 g) and the mixture heated to reflux (˜65° C.) for 72 hours whilst stirring. The mixture was then allowed to cool before being filtered and the catalyst residue washed with methanol (3×25 mL). The catalyst residue was then dried in vacuo for 24 hours to afford a white solid of 2-ethylpyridine doped H-mordenite.

Preparation of Catalyst C

[0069] 3-ethylpyridine (0.14 mL) was dissolved in methanol (25 mL) before being added to Catalyst A (2 g) and the mixture heated to reflux (˜65° C.) for 72 hours whilst stirring. The mixture was then allowed to cool before being filtered and the catalyst residue washed with methanol (3×25 mL). The catalyst residue was then dried in vacuo for 24 hours to afford a white solid of 3-ethylpyridine doped H-mordenite.

Preparation of Catalyst D

[0070] 4-ethylpyridine (0.14 mL) was dissolved in methanol (25 mL) before being added to Catalyst A and the mixture heated to reflux (˜65° C.) for 72 hours whilst stirring. The mixture was then allowed to cool before being filtered and the catalyst residue washed with methanol (3×25 mL). The catalyst residue was then dried in vacuo for 24 hours to afford a white solid of 4-ethylpyridine doped H-mordenite.

Preparation of Catalyst E

[0071] 4-hydroxypyridine (0.35 g) was dissolved in methanol (25 mL) before being added to Catalyst A (2 g) and the mixture heated to reflux (˜65° C.) for 72 hours whilst stirring. The reaction mixture was then allowed to cool before being filtered and the catalyst residue washed with methanol (3×25 mL). The catalyst residue was then dried in vacuo for 24 hours to afford a white solid of 4-hydroxypyridine doped H-mordenite.

Preparation of Catalyst F

[0072] 4-methoxypyridine (0.262 mL) was dissolved in methanol (25 mL) before being added to Catalyst A (2 g) and the mixture heated to reflux (˜65° C.) for 72 hours whilst stirring. The reaction mixture was then allowed to cool before being filtered and the catalyst residue washed with methanol (3×25 mL). The catalyst residue was then dried in vacuo for 24 hours to afford a white solid of 4-methoxypyridine doped H-mordenite.

Preparation of Catalyst G

[0073] Pyridine (0.21 mL) was dissolved in methanol (25 mL) before being added to Catalyst A (2 g) and the mixture heated to reflux (˜65° C.) for 72 hours whilst stirring. The reaction mixture was then allowed to cool before being filtered and the catalyst residue washed with methanol (3×25 mL). The catalyst residue was then dried in vacuo for 24 hours to afford a white solid of pyridine doped H-mordenite.

Preparation of Catalyst K

[0074] 2.02 g of Catalyst A was loaded into a tubular glassware reactor. Nitrogen was passed over the catalyst for 1 hour at 50 mL/min whilst at ambient temperature and pressure. The reactor was then heated to 150° C. at 5° C./min. A gas feed of nitrogen was sparged though a saturator containing liquid pyridine at room temperature and then passed over the catalyst for 1.5 hours at 50 mL/min. A nitrogen only gas feed was then passed over the catalyst at 100 mL/min and the reactor held at 150° C. for 30 minutes. The temperature was then ramped to 450° C. at 5° C./min and held for 24 hours. The heater was cooled to room temperature whilst nitrogen was passed over it at 50 mL/min and the catalyst removed.

Preparation of Catalyst L—Neat Pyridine, No Solvent

[0075] Pyridine (25 mL) was added to Catalyst A (2 g) and the mixture heated to reflux (˜65° C.) for 72 hours without stirring. The reaction mixture was then allowed to cool before being filtered and the catalyst residue was then dried in vacuo for 24 hours to afford a white solid of pyridine doped H-mordenite.

Preparation of Catalyst M, neat 3-.sup.nbutylpyridine, no solvent

[0076] 3-.sup.nbutylpyridine (25 mL) was added to Catalyst A (2 g) and the mixture heated to 80° C. for 72 hours whilst stirring. The reaction mixture was then allowed to cool before being filtered and the catalyst residue was then dried in vacuo for 48 hours to afford a white solid of 3-.sup.nbutylpyridine doped H-mordenite.

General Reaction Method and Apparatus

[0077] The ethanol dehydration reactions were carried out using a 16-channel parallel fixed-bed stainless steel reactor system. Each reactor housed a 25 mg bed of catalyst (having particle size fraction of 100 to 200 microns diameter) loaded on top of a 6 cm deep bed of an inert material (carborundum). The reactor volume above the catalyst was also packed with carborundum.

[0078] Each reactor (2 mm internal diameter) was initially purged with a feed of inert gas (helium and nitrogen mixture) for a period of approximately 20 hours, after which time each reactor was heated to a temperature of 150° C. at the start of the reaction and was maintained at a total pressure of 1100 kPa throughout the reaction. A gaseous feed comprising 10 mol % ethanol and inert gas (8.18 mol % He and 81.82 mol % nitrogen) was introduced into the reactor at a temperature of 150° C. and allowed to flow through the catalyst bed. This total gaseous feed to each reactor was 133 mmol h.sup.−1. After 24 hours at 150° C., each reactor was then heated via a series of temperature steps (180° C., 210° C., 230° C. and 250° C.) to a final reaction temperature of 270° C. A dwell time of approximately 24 hours was applied at each temperature step.

[0079] The effluent stream from each reactor was diluted with inert gas (nitrogen) and was periodically analysed by online gas chromatography to determine the yields of diethyl ether and ethylene products, and ethane and acetaldehyde by-products.

[0080] The Catalyst A to M were tested for the dehydration of ethanol using the General Reaction Method and Apparatus described above. Tables 1, 2, 3 and 4 list the ethanol (EtOH) conversion, and the space time yield (STYW) of diethyl ether (DEE), ethylene, ethane and acetaldehyde measured at reaction temperatures of 210, 230, 250 and 270° C., respectively. The addition of the dopant significantly reduces the yields of diethyl ether, ethane and acetaldehyde compared to Catalyst A.

[0081] Table 5 lists the results from elemental compositional analysis of Catalysts A to M. Table 5 lists the weight % concentration of the catalysts. The results show Catalysts B to M have higher carbon and nitrogen content than Catalyst A due to the adsorption of the optionally substituted pyridine compounds.

TABLE-US-00001 TABLE 1 Data at 210° C. reaction temperature Time on Catalyst EtOH Ethylene Ethane in C2 Acetaldehyde Stream mass conversion STYW DEE STYW hydrocarbons STYW Catalyst Dopant (TOS) (h) (mg) (%) (gkg.sub.cat.sup.−1h.sup.−1) (gkg.sub.cat.sup.−1h.sup.−1) (ppm) (gkg.sub.cat.sup.−1h.sup.−1) A* None 93.9 25 81.0 1434 14044  1554  0.014 B 2-Ethylpyridine 92.6 25 13.9 1603 610 286 0.009 C 3-Ethylpyridine 92.0 25 11.2 1478 282 250 0.009 D 4-Ethylpyridine 93.8 25 13.4 1479 265 617 0.011 E 4-Hydroxypyridine 92.8 25 8.3 972  88   0** 0.007 F 4-Methoxypyridine 93.6 25 8.3 1061  97   0** 0.007 G Pyridine 91.1 25 9.3 1149 340 158 0.007 K Pyridine (vapour phase 94.5 25 16.6 2026 418 175 0.005 impregnation) L Pyridine (no solvent) 93.2 25 10.9 1345 301 113 0.004 M 3-.sup.nbutylpyridine (no solvent) 92.8 25 5.8 814   0**   0** 0.004 *Not of the invention **Below detection limit Space Time Yield (STYW) is quoted in grammes of product per kilogramme of catalyst per hour, g kg.sub.cat.sup.−1h.sup.−1 DEE STYW detection limit: 0.15 gkg.sub.cat.sup.−1h.sup.−1 Ethane in ethylene detection limit: 0.03 ppm Ethane make quoted on a mole ppm basis relative to the sum of moles of C2 hydrocarbons produced (moles ethylene + moles ethane)

TABLE-US-00002 TABLE 2 Data at 230° C. reaction temperature Catalyst EtOH Ethylene DEE STYW Ethane in C2 Acetaldehyde TOS mass conversion STYW (g hydrocarbons STYW Catalyst Dopant (h) (mg) (%) (gkg.sub.cat.sup.−1h.sup.−1) kg.sub.cat.sup.−1h.sup.−1) (ppm) (gkg.sub.cat.sup.−1h.sup.−1) A* None 118.6 25 84.5 4345 10349  970 0.042 B 2-Ethylpyridine 117.2 25 32.7 4189 411 775 0.025 C 3-Ethylpyridine 116.7 25 33.1 4301 261 322 0.011 D 4-Ethylpyridine 118.4 25 33.8 4338 228 607 0.023 E 4-Hydroxypyridine 117.4 25 25.2 3148 143 81 0.018 F 4-Methoxypyridine 118.2 25 26.2 3245 151 62 0.014 G Pyridine 115.7 25 27.6 3406 479 107 0.011 K Pyridine (vapour phase 120 25 40.7 5365 446 207 0.005 impregnation) L Pyridine (no solvent) 118.3 25 29.9 3918 422 76 0.004 M 3-.sup.nbutylpyridine (no solvent) 117.8 25 11.2 1579   0** 166 0.004 *Not of the invention **Below detection limit Space Time Yield (STYW) is quoted in grammes of product per kilogramme of catalyst per hour, g kg.sub.cat.sup.−1h.sup.−1 DEE STYW detection limit: 0.15 gkg.sub.cat.sup.−1h.sup.−1 Ethane make quoted on a mole ppm basis relative to the sum of moles of C2 hydrocarbons produced (moles ethylene + moles ethane)

TABLE-US-00003 TABLE 3 Data at 250° C. reaction temperature Catalyst EtOH Ethylene DEE STYW Ethane in C2 Acetaldehyde TOS mass conversion STYW (g hydrocarbons STYW Catalyst Dopant (h) (mg) (%) (gkg.sub.cat.sup.−1h.sup.−1) kg.sub.cat.sup.−1h.sup.−1) (ppm) (gkg.sub.cat.sup.−1h.sup.−1) A* None 143.1 25 88.6 9250 3945  1144 0.090 B 2-Ethylpyridine 141.8 25 47.5 6474 116 981 0.030 C 3-Ethylpyridine 141.2 25 64.9 8875 132 229 0.023 D 4-Ethylpyridine 142.9 25 65.8 8852 132 466 0.021 E 4-Hydroxypyridine 141.9 25 52.6 7174 126 69 0.018 F 4-Methoxypyridine 142.7 25 51.7 6940 131 53 0.016 G Pyridine 143.3 25 58.0 7451 490 75 0.018 K Pyridine (vapour phase 144.3 25 74.7 10201 209 183 0.011 impregnation) L Pyridine (no solvent) 143.0 25 63.9 8715 445 89 0.005 M 3-.sup.nbutylpyridine (no solvent) 142.4 25 17.3 2397   0** 178 0.005 *Not of the invention **Below detection limit Space Time Yield (STYW) is quoted in grammes of product per kilogramme of catalyst per hour, g kg.sub.cat.sup.−1h.sup.−1 DEE STYW detection limit: 0.15 gkg.sub.cat.sup.−1h.sup.−1 Ethane make quoted on a mole ppm basis relative to the sum of moles of C2 hydrocarbons produced (moles ethylene + moles ethane)

TABLE-US-00004 TABLE 4 Data at 270° C. reaction temperature Catalyst EtOH Ethylene DEE STYW Ethane in C2 Acetaldehyde TOS mass conversion STYW (g hydrocarbons STYW Catalyst Dopant (h) (mg) (%) (gkg.sub.cat.sup.−1h.sup.−1) kg.sub.cat.sup.−1h.sup.−1) (ppm) (gkg.sub.cat.sup.−1h.sup.−1) A* None 167.6 25 96.9 10799 3112 4273 0.123 B 2-Ethylpyridine 166.3 25 45.5 6057 39 241 0.023 C 3-Ethylpyridine 165.7 25 91.9 12488 66 147 0.033 D 4-Ethylpyridine 167.4 25 91.2 12237 60 140 0.030 E 4-Hydroxypyridine 166.5 25 79.0 11009 59 75 0.026 F 4-Methoxypyridine 167.2 25 74.4 10036 167 78 0.023 G Pyridine 167.8 25 89.7 11755 334 75 0.025 K Pyridine (vapour phase 191.2** 25 95.6 13174 76 152 0.019 impregnation) L Pyridine (no solvent) 189.9** 25 94.2 13085 257 102 0.011 *Not of the invention **An additional dwell time of approximately 24 hours at 260° C. was included in the reaction method for Catalysts K and L Space Time Yield (STYW) is quoted in grammes of product per kilogramme of catalyst per hour, g kg.sub.cat.sup.−1h.sup.−1 Ethane make quoted on a mole ppm basis relative to the sum of moles of C2 hydrocarbons produced (moles ethylene + moles ethane)

TABLE-US-00005 TABLE 5 Analytical information for catalysts Catalyst Dopant C (wt. %) N (wt. %) A* None  0** 0.3 B 2-Ethylpyridine  8.0 1.5 C 3-Ethylpyridine 11.3 1.0 D 4-Ethylpyridine  5.3 0.9 E 4-Hydroxypyridine  5.6 1.3 F 4-Methoxypyridine  6.6 1.3 G Pyridine  5.9 1.0 K Pyridine (vapour phase impregnation)  3.8 1.0 L Pyridine (no solvent)  6.7 1.7 M 3-.sup.nbutylpyridine (no solvent) 10.1 1.5 **Below detection limit; detection limit: <0.1 wt. % for C, H and N.