Carbonylation process for the production of methyl acetate

Abstract

A process for the production of methyl acetate by carbonylating at a temperature of 250 to 350° C., in the presence of a zeolite catalyst, a feed comprising dimethyl ether, a gas comprising carbon monoxide and hydrogen at a molar ratio of hydrogen to carbon monoxide of at least 1, methyl acetate and one or more compounds containing a hydroxyl functional group.

Claims

1. A process for the carbonylation of dimethyl ether with carbon monoxide in the presence of a catalyst comprising a templated zeolite to produce a reaction product comprising methyl acetate wherein the process is carried out at a temperature of from 250 to 350° C., the feed to the process comprises dimethyl ether, carbon monoxide, hydrogen, methyl acetate, and one or more hydroxyl compound(s) selected from water, a C.sub.1-C.sub.4 aliphatic alcohol, and a C.sub.1-C.sub.4 aliphatic carboxylic acid; the molar ratio of hydrogen to carbon monoxide in the feed is at least 1, and the molar ratio of methyl acetate to the one or more hydroxyl compound(s) is in the range 500:1 to 0.5:1.

2. The process according to claim 1 wherein the feed comprises the hydroxyl compound(s) in a total amount of up to 1 mol % based on a total gaseous feed to the process including the hydroxyl compound(s), dimethyl ether, carbon monoxide, hydrogen, and methyl acetate.

3. The process according to claim 1 wherein the feed comprises the hydroxyl compound(s) in a total amount of 0.01 to 0.5 mol % based on a total gaseous feed to the process including the hydroxyl compound(s), dimethyl ether, carbon monoxide, hydrogen, and methyl acetate.

4. The process according to claim 1, wherein the feed comprises methyl acetate and the hydroxyl compound(s) at a molar ratio of methyl acetate to hydroxyl compound(s) in the range 300:1 to 1:1.

5. The process according to claim 1, wherein the hydroxyl compound is water.

6. The process according to claim 1 wherein the hydroxyl compound is a C.sub.1-C.sub.4 aliphatic alcohol.

7. The process according to claim 1 wherein the hydroxyl compound is a C.sub.1-C.sub.4 aliphatic carboxylic acid.

8. The process according to claim 1 wherein the hydroxyl compound is selected from one or more of water, acetic acid and methanol.

9. The process according to claim 1, wherein the feed comprises hydrogen and carbon monoxide at a molar ratio of hydrogen to carbon monoxide in the range 1.5 to 4:1.

10. The process according to claim 1, wherein the feed comprises methyl acetate in an amount up to 5 mol % based on a total gaseous feed to the process including the hydroxyl compound(s), dimethyl ether, carbon monoxide, hydrogen, and methyl acetate.

11. The process according to claim 1, wherein the catalyst is a zeolite having at least one channel which is defined by an 8-membered ring.

12. The process according to claim 11 wherein the zeolite has a framework type selected from the group consisting of MOR, FER, OFF, CHA, GME, MFS, EON and ETR.

13. The process according to claim 12 wherein the zeolite has the framework type MOR and is mordenite.

14. The process according to claim 1, wherein the process is carried out at a temperature of from 275 to 325° C.

15. The process according to claim 1, wherein methyl acetate product is hydrolysed to acetic acid.

16. A method of maintaining or reducing the deactivation rate of a catalyst in a process for the carbonylation of dimethyl ether with carbon monoxide in the presence of a catalyst comprising a templated zeolite to produce a reaction product comprising methyl acetate in which method, the process is carried out at a temperature of from 250 to 350° C., the feed to the process comprises dimethyl ether, carbon monoxide, hydrogen, methyl acetate, and one or more hydroxyl compound(s) selected from water, a C.sub.1-C.sub.4 aliphatic alcohol, and a C.sub.1-C.sub.4 aliphatic carboxylic acid, the molar ratio of hydrogen to carbon monoxide in the feed is at least 1, and the molar ratio of methyl acetate to the one or more hydroxyl compound(s) is in the range 500:1 to 0.5:1.

17. The process according to claim 1, wherein the feed to the process includes one or more gaseous recycles, and the feed comprises methyl acetate in an amount up to 5 mol % based on a total gaseous feed, including gaseous recycles, to the process including the hydroxyl compound(s), dimethyl ether, carbon monoxide, hydrogen, and methyl acetate.

18. The process according to claim 1, wherein the feed comprises methyl acetate and the hydroxyl compound(s) at a molar ratio of methyl acetate to hydroxyl compound(s) in the range 100:1 to 4:1.

19. The process according to claim 1, wherein the feed comprises methyl acetate, present in an amount of from 0.5 to 5.0 mol %; and one or more hydroxyl compounds selected from water, acetic acid, and methanol, present in a combined amount of from 0.03 to 0.5 mol %.

20. The process according to claim 1, wherein methyl acetate is present in the feed in an amount of less than 2 mol %; one or more of water, acetic acid and methanol are present in the feed in a combined amount of from 0.03 to 0.2 mol %; hydrogen and carbon monoxide are present in the feed in a molar ratio in the range 1.5:1 to 4:1; and the process is carried out at a temperature of from 275 to 325° C.

Description

EXAMPLE 1

(1) This Example demonstrates carbonylation of dimethyl ether with carbon monoxide in the presence of a templated zeolite catalyst under hydrogen-rich conditions and utilising feeds comprising (i) methyl acetate and water or acetic acid and (ii) methyl acetate.

(2) The carbonylation reactions were conducted in a reactor (length 1215 mm and internal diameter 20.4 mm) containing a 137.4 mL bed of templated mordenite catalyst in the form of 3.2 mm diameter extrudates. The temperature of the catalyst bed was determined from thermocouples positioned at a number of points within the bed.

(3) A gaseous feed stream of 9 mol % dimethyl ether, carbon monoxide and hydrogen at a molar ratio of 1:4 and 2.97 mol % methyl acetate doped with water (so as to provide a water concentration of 0.03 mol % in the total feed) (“water-doped feed”) was supplied to the reactor under reaction conditions of a pressure of 70 barg (7000 kPa), a temperature of 283° C. and a gas hourly space velocity of 4000 h.sup.−1 for a period of 264 hours (Period A). Following Period A, the water-doped feed was replaced by a feed of 3 mol % methyl acetate containing essentially no water (“non-doped feed”) and the reaction was allowed to continue under these conditions for a period of 96 hours (Period B). Following Period B, the non-doped feed was replaced by the water-doped feed and the reaction was allowed to continue under these conditions for 192 hours (Period C). Following Period C, the water-doped feed was replaced with the non-doped feed and the reaction was allowed to continue under these conditions for 120 hours (Period D). Following Period D, the non-doped feed was replaced by a 2.97 mol % methyl acetate feed doped with acetic acid (so as to provide an acetic acid concentration of 0.03 mol % in the total feed) (“acid-doped feed”) and the reaction was allowed to continue under these conditions for 200 hours (Period E).

(4) The effluent stream from the reactor was periodically analysed on two Varian gas chromatographs to determine the concentration of carbonylation reactants and products. The first gas chromatograph was equipped with two FID detectors and the second gas chromatograph was fitted with two TCD detectors.

(5) The results of the experiments are shown in Tables 1 and 2 below. The rate of deactivation of the catalyst was determined by the change (° C. loss per day) in the average internal catalyst bed temperature.

(6) TABLE-US-00001 TABLE 1 Time Hydroxyl Catalyst deactivation rate Period compound (° C. loss per day) A water 0.00 B none 0.22 C water 0.00 D none 0.18 E acetic acid 0.01

(7) As can be seen from the results in Table 1, the catalyst deactivation rates in the carbonylation reactions conducted with feeds containing a hydroxyl compound were significantly reduced compared to the deactivation rates using feeds which did not contain a hydroxyl compound.

(8) The results in Table 2 show the impact of using feeds with and without hydroxyl compounds on the production of by-product methane in the reactions of Example 1.

(9) TABLE-US-00002 TABLE 2 Time Hydroxyl Methane STY Period compound (gLcat.sup.−1h.sup.−1) A water 6.0 B none 4.0 C water 5.5 D none 3.5 E acetic acid 4.0

EXAMPLE 2

(10) Using the apparatus and 91.6 mL catalyst as described in Example 1 above, a gaseous carbonylation feed of carbon monoxide and hydrogen at a molar ratio of 1:4, 9 mol % dimethyl ether and 0.94 mol % methyl acetate doped with acetic acid (so as to provide an acetic acid concentration of 0.06 mol % in the total feed) was fed to the reactor under reaction conditions of a pressure of 70 barg (7000 kPa), a temperature of 286° C. and a gas hourly space velocity of 6000 h.sup.−1 for 350 hours (Period A). After Period A, the methyl acetate doped feed was changed to a feed of 1.88 mol % methyl acetate doped with acetic acid (so as to provide an acetic acid concentration of 0.12 mol % in the total feed) and the reaction was allowed to continue under these conditions for 161 hours (Period B). After Period B, the methyl acetate doped feed was changed to a feed of 0.88 mol % methyl acetate doped with acetic acid (so as to provide an acetic acid concentration of 0.12 mol % in the total feed) and the reaction was allowed to continue under these conditions (Period C).

(11) The results of the experiments are shown in Table 3 below. Deactivation rates of the catalyst were determined by the change (° C. loss per day) in the average internal catalyst bed temperature. The amounts of feed components in the Table are based on the total feed to the reactor.

(12) TABLE-US-00003 TABLE 3 Amount of Amount of Catalyst Time methyl acetate acetic acid deactivation rate Period (mol %) (mol %) (° C. loss per day) A 0.94 0.06 0.08 B 1.88 0.12 0.00 C 0.88 0.12 0.00

(13) The results in Table 3 demonstrate that the deactivation rate of a templated zeolite catalyst, utilised in reactions for the carbonylation of dimethyl ether carried out under hydrogen-rich conditions, can be effectively maintained by utilising acetic acid as a component of the reaction feed. The methyl acetate concentration used in Period C was reduced by approximately half of that used in Period B. No detrimental effect was observed to the catalyst deactivation rate in Period C. This demonstrates that use of acetic acid as a component of a carbonylation reaction feed is beneficial to maintaining catalyst deactivation rate and consequently, catalyst lifetime.

EXAMPLE 3

(14) Using the apparatus and 91.6 mL catalyst as described in Example 1 above, a gaseous carbonylation feed of carbon monoxide and hydrogen in a molar ratio of 1:4, 9 mol % dimethyl ether and 0.81 mol % methyl acetate doped with acetic acid (so as to provide an acetic acid concentration of 0.19 mol % in the total feed) was supplied to the reactor under reaction conditions of a pressure of 70 barg (7000 kPa), a temperature of 286° C. and a gas hourly space velocity of 6000 h.sup.−1 for 80 hours (Period A). Following Period A, the hydrogen:carbon monoxide molar ratio was changed to a molar ratio of 2.5H.sub.2:1CO and the reaction was allowed to continue under these conditions for 317 hours (Period B). Following Period B, the acid-doped methyl acetate feed was replaced by a feed of 0.81 mol % methyl acetate doped with methanol (so as to provide a methanol concentration of 0.19 mol % in the total feed) and the reaction allowed to continue under these conditions for a period of 60 hours (Period C). The deactivation rate of the catalyst was determined by the change (° C. loss per day) in the average internal catalyst bed temperature. The results of Example 3 are shown in Table 4 below.

(15) TABLE-US-00004 TABLE 4 Catalyst Time Hydroxyl H.sub.2:CO deactivation rate Period compound molar ratio (° C. loss per day) A acetic acid   4:1 0.00 B acetic acid 2.5:1 0.11 C methanol 2.5:1 0.00

(16) The results in Table 4 demonstrate that in Example 3 the use of methanol reduces the rate at which the catalyst deactivates more effectively than acetic acid.

EXAMPLE 4

(17) Using the apparatus and 109.9 mL of catalyst as described in Example 1 above, a gaseous carbonylation feed of carbon monoxide and hydrogen in a molar ratio of 1:1.75, 9 mol % dimethyl ether and 0.81 mol % methyl acetate doped with methanol (so as to provide a methanol concentration of 0.19 mol % in the total feed) was supplied to the reactor under reaction conditions of a pressure of 70 barg (7000 kPa), a temperature of 283° C. and a gas hourly space velocity of 5000 h for a period of 1040 hours (Period A). After Period A, the methanol-doped methyl acetate feed was changed to a feed of 0.81 mol % methyl acetate feed doped with acetic acid (so as to provide an acetic acid concentration of 0.19 mol % in the total feed) and the reaction was allowed to continue under these conditions for 46 hours (Period B). After Period B, the doped methyl acetate feed to the reactor was ceased and the reaction allowed to continue in the absence of the methyl acetate doped feed for a period of 114 hours (Period C). The deactivation rate of the catalyst was determined by the change (° C. loss per day) in the average internal catalyst bed temperature. The results of Example 4 are shown in Table 5 below.

(18) TABLE-US-00005 TABLE 5 Catalyst Time Hydroxyl deactivation rate Period compound (° C. loss per day) A methanol 0.00 B acetic acid 0.06 C none 0.83

(19) The results in Table 5 demonstrate that the rate of catalyst deactivation is reduced if methanol or acetic acid is present as a component of the feed to the carbonylation reaction.

EXAMPLE 5

(20) Using the apparatus and 110.0 mL catalyst as described in Example 1 above, a gaseous carbonylation feed of carbon monoxide and hydrogen at a molar ratio of 1:1.8, 9 mol % dimethyl ether and 0.85 mol % methyl acetate doped with acetic acid (so as to provide an acetic acid concentration of 0.15 mol % in the total feed) was supplied to the reactor under reaction conditions of a pressure of 70 barg (7000 kPa), a temperature of 280° C. and a gas hourly space velocity of 5000 h.sup.−1 for a period of 1057 hours (Period A). After Period A, the methyl acetate doped feed was changed to 0.80 mol % methyl acetate doped with acetic acid (so as to provide acetic acid at a concentration of 0.20 mol % based on the total feed), the temperature was increased to 297.5° C. and the reaction was allowed to continue under these conditions for 840 hours (Period B). After Period B, the methyl acetate doped feed was maintained but the temperature was increased to 299.5° C. and the reaction was allowed to continue under these conditions for 52 hours (Period C). After Period C, the methyl acetate doped feed was changed to 0.80 mol % methyl acetate doped with methanol (so as to provide methanol at a concentration of 0.20 mol % based on the total feed), the temperature was increased to 301.5° C. and the reaction was allowed to continue under these conditions for 106 hours (Period D). After Period D, the methyl acetate doped feed was changed to 0.90 mol % methyl acetate doped with water (so as to provide water at a concentration of 0.10 mol % based on the total feed), the temperature was increased to 312.0° C. and the reaction was allowed to continue under these conditions for 110 hours (Period E). After Period E, the methyl acetate doped feed was changed to 0.82 mol % methyl acetate doped with water, acetic acid and methanol (so as to provide water, acetic acid and methanol at a concentration of 0.02, 0.01 and 0.15 mol % respectively based on the total feed), the temperature was maintained at 312° C. and the reaction was allowed to continue under these conditions for 30 hours (Period F).

(21) The deactivation rate of the catalyst was determined by the change (° C. loss per day) in the average internal catalyst bed temperature. The results of Example 5 are shown in Table 6 below.

(22) TABLE-US-00006 TABLE 6 Amount Amount of of methyl hydroxyl Catalyst Time acetate Hydroxyl compound deactivation rate Period (mol %) Compound (mol %) (° C. loss per day) A 0.85 acetic acid 0.15 0.02 B 0.80 acetic acid 0.20 0.01 C 0.80 acetic acid 0.20 0.00 D 0.80 methanol 0.20 0.02 E 0.90 water 0.10 0.00 F 0.82 water, methanol 0.18 0.03 and acetic acid

(23) The results in Table 6 demonstrate that the deactivation rate of the catalyst can be effectively maintained by adding to the process any one of acetic acid, methanol, water or a mixture thereof.

EXAMPLE 6

(24) This example was carried out using a stainless steel pipe reactor of 0.4 mm internal diameter containing a 2.0 mL bed of 3.2 mm diameter templated mordenite catalyst extrudates with any interstitial voids filled with ceramic beads. The reactor was heated to the desired reaction temperature and pressurised to 70 barg (7000 kPa).

(25) A gaseous feed of 9 mol % dimethyl ether, 0.85 mol % methyl acetate doped with acetic acid to provide a concentration of 0.15 mol % acetic acid in the total feed, 5 mol % helium and carbon monoxide and hydrogen in a molar ratio of 1:2.5 was supplied to the reactor at a gas hourly space velocity of 4000 h.sup.−1 for 192 hours (Period A) under the reaction conditions of 300° C. and 70 barg (7000 kPa).

(26) After Period A, the methyl acetate doped feed was switched off and the carbonylation reaction was allowed to continue at 300° C. and 70 barg (7000 kPa) for a period of 79 hours (Period B).

(27) The gaseous effluent stream from the reactor was diluted with 200 mL/min nitrogen, reduced to atmospheric pressure and periodically analysed during Periods A and B, using two Agilent gas chromatographs, to determine the concentration of carbonylation reactants and products. The first chromatograph was equipped with two FID detectors and the second with two TCD detectors.

(28) The deactivation rate of the catalyst was determined by the % change in the acetyls STY (gLcat.sup.−1 h.sup.−1) per day. A negative % STY change per day indicates that the catalyst is deactivating.

(29) The results of this Example are shown in Table 7 below.

(30) TABLE-US-00007 TABLE 7 Hydroxyl Deactivation Rate Period compound (% STY change per day) A acetic acid 0.0 B none −4.5

(31) The results in Table 7 demonstrate that during Period B when no acetic acid was present, the catalyst was deactivating whereas in Period A, the catalyst was found to be stable. These results show that the presence of acetic acid in the carbonylation feed mitigates catalyst deactivation.

EXAMPLE 7

(32) Using the reactor as described above in Example 6, Example 6 was repeated except that the gaseous feed to the reactor had 0.80 mol % methyl acetate doped with methanol to provide a concentration of 0.20 mol % methanol in the total feed, and the reaction was carried out at a temperature of 292° C. The results of Example 7 are shown in Table 8 below.

(33) TABLE-US-00008 TABLE 8 Hydroxyl Deactivation Rate Period compound (% STY change per day) A methanol 0.0 B none −3.3

(34) The results in Table 8 demonstrate that during Period B when methanol was not used as a component of the feed, the catalyst was deactivating whereas in Period A, the catalyst was found to be stable. These results show that the presence of methanol in the carbonylation feed mitigates catalyst deactivation.

EXAMPLE 8

(35) Using the reactor as described above in Example 6, Example 6 was repeated except that the gaseous feed to the reactor had 0.90 mol % methyl acetate doped with water to provide a concentration of 0.10 mol % water in the total feed, and the reaction was carried out at a temperature of 297° C. The results of Example 8 are shown in Table 9 below.

(36) TABLE-US-00009 TABLE 9 Hydroxyl Deactivation Rate Period compound (% STY change per day) A water 0.0 B none −2.9

(37) The results in Table 9 demonstrate that during Period B when water was not used as a component of the feed, the catalyst was deactivating whereas in Period A, the catalyst was found to be stable. These results show that the presence of water in the carbonylation feed mitigates catalyst deactivation.