阅读说明：本技术 催化剂再活化方法 (Catalyst reactivation process ) 是由 斯里坎特·戈帕尔 图尔基·阿尔斯马里 沙希德·阿扎姆 哈利德·卡里姆 于 2020-03-26 设计创作，主要内容包括：公开了使用和再生用于由乙烷生产乙酸的催化剂的系统和方法。使包含乙烷和包括氧气的氧化剂的进料料流流向反应器,在该反应器中设置有包含MoVNbPd氧化物的催化剂。乙烷和氧化剂在催化剂存在下在足以产生乙酸的反应条件下反应。当催化剂催化乙烷和氧化剂之间反应的能力降低预定百分比时,停止进料料流向反应器的流动。使再生气体料流流经反应器,以在操作条件下使再生气体料流与催化剂接触,以增加催化剂催化乙烷和氧化剂之间反应的能力。(Systems and methods for using and regenerating a catalyst for the production of acetic acid from ethane are disclosed. A feed stream comprising ethane and an oxidant comprising oxygen is flowed to a reactor in which a catalyst comprising MoVNbPd oxide is disposed. Ethane and an oxidant are reacted in the presence of a catalyst under reaction conditions sufficient to produce acetic acid. The flow of the feed stream to the reactor is stopped when the catalyst's ability to catalyze the reaction between ethane and the oxidant decreases by a predetermined percentage. The regeneration gas stream is flowed through the reactor to contact the regeneration gas stream with the catalyst at operating conditions to increase the ability of the catalyst to catalyze a reaction between ethane and an oxidant.)

1. A method of using and regenerating a catalyst for the production of acetic acid from ethane, the method comprising:

flowing (1) a feed gas comprising ethane and (2) an oxidant comprising oxygen into a reactor in which is disposed a catalyst comprising an oxide of MoVNbPd;

reacting ethane with an oxidant in the presence of a catalyst in a reactor to produce acetic acid;

stopping the flow of feed gas and oxidant to the reactor when the catalyst's ability to catalyze the reaction between ethane and oxidant decreases by 30% or more; and

subjecting a regeneration gas stream comprising 2 to 21 mol% oxygen to a temperature of 200 to 375 ℃ and a pressure of 1000 to 10,000h^-1Is flowed through the reactor to contact the regeneration gas stream with the catalyst to increase the ability of the catalyst to catalyze the reaction between ethane and the oxidant.

2. The process of claim 1, wherein the regeneration gas stream is flowed through the reactor after the reactor has been in operation for at least 3 months.

3. The method of claim 1, further comprising flushing a feed line to a reactor and the reactor with an inert gas prior to flowing the regeneration gas stream.

4. The method of claim 3, wherein the inert gas is selected from the group consisting of nitrogen, argon, CO₂And combinations thereof.

5. The process of any of claims 1 to 4, wherein the regeneration gas stream flows through the reactor for at least 3 to 24 hours.

6. The process according to any one of claims 1 to 4, wherein the reactor is maintained at a temperature that prevents the formation of liquid water.

7. The process of any of claims 1 to 4, wherein the regeneration gas stream further comprises nitrogen, carbon dioxide, argon, or a combination thereof.

8. A process according to any one of claims 1 to 4 wherein flowing the regeneration gas through the reactor is capable of restoring the activity of the catalyst to 70 to 100% of that of fresh catalyst.

9. The process of any one of claims 1 to 4, further comprising recycling unreacted ethane and/or unreacted oxidant to the reactor.

10. The process of any one of claims 1 to 4, wherein the reactor comprises a fixed bed reactor, a fluidized bed reactor, or a combination thereof.

11. The process of any one of claims 1 to 4, wherein the catalyst is supported on alumina, silica, titania, zinc oxide, or a combination thereof.

12. The process according to any one of claims 1 to 4, wherein the reaction is carried out at a temperature of 150 to 450 ℃.

13. A process according to any one of claims 1 to 4, wherein the reaction is carried out at a pressure of from 1 to 50 bar.

14. The process according to any one of claims 1 to 4, wherein the reaction is carried out for 50 to 50000hr^-1At a gas hourly space velocity of (a).

15. The process according to any one of claims 1 to 4, wherein the molar ratio of oxygen and ethane flowing into the reactor is in the range of 1:1000 to 1: 1.

16. The method of any one of claims 1 to 4, further comprising removing the CO by removing the CO₂And/or water to purify the acetic acid.

Technical Field

The present invention generally relates to methods of using and regenerating catalysts for the production of acetic acid. More particularly, the present invention relates to a process for using and regenerating a catalyst suitable for catalyzing the oxidation of ethane to produce acetic acid.

Background

Acetic acid is a chemical agent used to produce plastic bottles, photographic films, polyvinyl acetate (for wood glues) and synthetic fibers and fabrics. Acetic acid is also commonly used as a cleaning agent, an acidity regulator for food, and a seasoning.

There are a number of processes for the production of acetic acid in the chemical industry. One such process is the oxidation of ethane. In this process, ethane and an oxidant are reacted in the presence of a catalyst at elevated temperature and pressure to form acetic acid. However, the performance of the catalyst gradually declines over time in the process, leading to various problems, including increased formation of carbon dioxide and water, increased catalyst temperature, and decreased acetic acid productivity.

The increase in carbon dioxide and water formation may result in an increase in the energy consumption of the carbon dioxide removal unit and the water removal unit used to purify the acetic acid. The gradual increase in the operating temperature of the catalyst may bring the catalyst to a temperature at which the rate of production of acetic acid is significantly lower than when fresh catalyst is used. Furthermore, increased operating temperatures may lead to higher safety risks. When this occurs, the catalyst needs to be replaced, which increases the production cost of acetic acid.

In general, despite the existence of processes for producing acetic acid, there remains a need in the art for improvements in view of at least the above-mentioned shortcomings of conventional processes.

Disclosure of Invention

A solution to at least some of the above-mentioned problems associated with processes for producing acetic acid using ethane and an oxidizing agent has been discovered. The solution is a method of using and regenerating a catalyst for the production of acetic acid. Typically, after 3 to 6 months or up to 24 months of continuous operation, when the catalyst's ability to catalyze the reaction between ethane and the oxidant decreases to a predetermined value or below a predetermined value, the method involves flowing an oxygen-containing regeneration gas stream over the catalyst at a temperature to increase the catalyst's ability to catalyze the reaction between ethane and the oxidant. The regenerated catalyst is then used to produce more acetic acid, for example for an additional 3 to 6 months, after which regeneration of the catalyst is again carried out. It should be noted that the time period between regenerations may vary. Thus, while the catalyst may typically be regenerated every 3 to 6 months, some catalysts may only need to be regenerated once a year. Regenerating the catalyst in this manner at least advantageously extends the catalyst life of the process, thereby reducing the cost of acetic acid production. Notably, the process is capable of reactivating a partially deactivated catalyst to greater than at least 70% of the activity and selectivity of a fresh catalyst, thereby forming less carbon dioxide and water during the production of acetic acid than conventional processes. In addition, the regeneration of the catalyst can prevent a gradual increase in the operating temperature of the catalyst, thereby improving the catalyst life and improving the safety level of the production system. The process of the present invention therefore provides a solution to at least some of the problems associated with currently available processes for the production of acetic acid from ethane.

Embodiments of the invention include methods of using and regenerating catalysts for the production of acetic acid from ethane. The method comprises flowing (1) a feed gas comprising ethane and (2) an oxidant comprising oxygen into a reactor in which is disposedA catalyst comprising an oxide of MoVNbPd is disposed. The process also includes reacting ethane with an oxidant in the presence of a catalyst in a reactor to produce acetic acid. The method also includes stopping the flow of the feed gas and the oxidant to the reactor when the catalyst's ability to catalyze the reaction between ethane and the oxidant decreases by 30% or more. The process further comprises subjecting the regeneration gas stream comprising 2 to 21 mol% oxygen to a temperature of 200 to 375 ℃ and 1000 to 10,000h^-1Is flowed through the reactor to contact the regeneration gas stream with the catalyst to increase the catalyst's ability to catalyze the reaction between ethane and the oxidant.

Embodiments of the invention include methods of using and regenerating catalysts for the production of acetic acid from ethane. The process includes flowing (1) a feed gas comprising ethane and (2) an oxidant comprising oxygen into a reactor having disposed therein a catalyst comprising an oxide of MoVNbPd. The process also includes reacting ethane with an oxidant in the presence of a catalyst in a reactor to produce acetic acid. The method also includes stopping the flow of the feed gas and the oxidant to the reactor when the catalyst's ability to catalyze the reaction between ethane and the oxidant decreases by 30% or more. The method also includes flushing the feed line to the reactor and the reactor with an inert gas. The process further comprises subjecting the regeneration gas stream comprising 2 to 21 mol% oxygen to a temperature of 200 to 375 ℃ and 1000 to 10,000h^-1Is flowed through the reactor to contact the regeneration gas stream with the catalyst to increase the ability of the catalyst to catalyze the reaction between ethane and the oxidant. The method further comprises purifying the acetic acid produced in the reacting step by removing by-products comprising carbon dioxide and/or water.

The following includes definitions for various terms and phrases used throughout the specification.

The term "about" or "approximately" is defined as being close to as understood by one of ordinary skill in the art. In one non-limiting embodiment, these terms are defined as being within 10%, preferably within 5%, more preferably within 1%, and most preferably within 0.5%.

The terms "weight%", "volume%" or "mole%" refer to the weight, volume, or mole percent of a component, respectively, based on the total weight, volume, or total moles of materials comprising the component. In a non-limiting example, 10mol of the component in 100mol of the material is 10 mol% of the component.

The term "substantially" and variations thereof are defined as ranges that include within 10%, within 5%, within 1%, or within 0.5%.

The terms "inhibit" or "reduce" or "prevent" or "avoid" when used in the claims and/or the specification, or any variation of these terms, includes any measurable amount of reduction or complete inhibition to achieve a desired result.

The term "effective" as used in the specification and/or claims means sufficient to achieve a desired, expected, or intended result.

The term "partially deactivated catalyst" or "deactivated catalyst" as used in the specification and/or claims refers to a catalyst having a catalytic activity that is less than 70% of the catalytic activity of a fresh catalyst of the same catalyst composition.

The use of the words "a" or "an" when used in the claims or the specification in conjunction with the terms "comprising," including, "" containing, "or" having "can mean" one, "but it also has the meaning of" one or more, "" at least one, "and" one or more than one.

The words "comprising" (and any form of comprising, such as "comprises" and "comprises"), "having" (and any form of having, such as "has" and "has"), "including" (and any form of including, such as "includes" and "includes") or "containing" (and any form of containing, such as "contains" and "contains") are inclusive or open-ended and do not exclude additional, unrecited elements or process steps.

The methods of the present invention can "comprise," "consist essentially of," or "consist of" the particular ingredients, components, compositions, etc. disclosed throughout the specification.

The term "predominantly", as that term is used in the specification and/or claims, means greater than any one of 50 weight percent, 50 mole percent, and 50 volume percent. For example, "predominantly" can include 50.1% to 100% by weight and all values and ranges therebetween, 50.1% to 100% by mole and all values and ranges therebetween, or 50.1% to 100% by volume and all values and ranges therebetween.

Other objects, features and advantages of the present invention will become apparent from the following drawings, detailed description and examples. It should be understood, however, that the drawings, detailed description, and examples, while indicating specific embodiments of the present invention, are given by way of illustration only, and not by way of limitation. In addition, it is contemplated that changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description. In other embodiments, features from specific embodiments may be combined with features from other embodiments. For example, features from one embodiment may be combined with features from any of the other embodiments. In further embodiments, additional features may be added to the specific embodiments described herein.

Drawings

For a more complete understanding, reference is now made to the following descriptions taken in conjunction with the accompanying drawings, in which:

FIG. 1 shows a schematic diagram of a system for using and regenerating a catalyst for the production of acetic acid, according to an embodiment of the invention; and is

Fig. 2 shows a schematic flow diagram of a method of regenerating and using a catalyst for the production of acetic acid according to an embodiment of the present invention.

Detailed Description

Currently, there are several problems associated with the oxidation of ethane to produce acetic acid, including increasing catalyst temperature over time and gradually decreasing catalyst activity and selectivity. A decrease in catalyst activity and selectivity can lead to an increase in the formation of carbon dioxide and water during the reaction, resulting in an increase in the energy consumption for separating carbon dioxide and water from the product stream. In addition, the decrease in catalyst activity also increases raw material consumption, resulting in a decrease in production efficiency. Increased catalyst temperature can greatly shorten the life of the catalyst, resulting in increased costs associated with replacing the catalyst. The present invention provides a solution to at least some of these problems. A prerequisite of this solution is a method for using and regenerating a catalyst for the production of acetic acid from ethane, which method comprises passing a stream of regeneration gas over the catalyst to restore the catalyst activity and selectivity to more than 70% of the fresh catalyst when the catalyst performance drops to a predetermined value during the reaction of ethane and oxidant. Typically, the catalyst may be regenerated every 3 to 6 months or annually. Thus, both the overall catalyst performance and catalyst life are improved, resulting in improved acetic acid production efficiency and reduced production costs as compared to conventional processes. These and other non-limiting aspects of the invention are discussed in further detail in the following sections.

A. Use and regeneration system for catalyst for acetic acid production

In embodiments of the invention, a system for using and regenerating a catalyst for the production of acetic acid from ethane can include one or more reactors and a product separation system including a carbon dioxide removal unit and a distillation unit. Referring to fig. 1, a schematic diagram of a system 100 is shown, the system 100 capable of producing acetic acid from ethane with improved production efficiency and reduced production costs compared to conventional processes. According to an embodiment of the present invention, the system 100 may include a feed heating unit 101 adapted to heat the feed stream 11 to a predetermined temperature to produce a heated feed stream 12. In embodiments of the present invention, the feed heating unit 101 may comprise a heat exchanger, a furnace, or a combination thereof. The predetermined temperature for feed stream 11 can be in the range of 150 to 450 ℃ and all ranges and values therebetween, including the ranges of 150 to 165 ℃, 165 to 180 ℃, 180 to 195 ℃, 195 to 210 ℃, 210 to 225 ℃, 225 to 240 ℃, 240 to 255 ℃, 255 to 270 ℃, 270 to 285 ℃, 285 to 300 ℃, 300 to 315 ℃, 315 to 330 ℃, 330 to 345 ℃, 345 to 360 ℃, 360 to 375 ℃, 375 to 390 ℃, 390 to 405 ℃, 405 to 420 ℃, 420 to 435 ℃, and 435 to 450 ℃. In an embodiment of the invention, the feed stream 11 may be a combined stream of the feed gas stream 13 and the oxidant stream 14.

According to an embodiment of the invention, the outlet of the feed heating unit 101 may be in fluid communication with the first inlet of the reaction unit 102 such that the heated feed stream 12 flows from the feed heating unit 101 to the reaction unit 102. In embodiments of the invention, the reaction unit 102 may include one or more reactors adapted to react ethane and an oxidant in the presence of a catalyst under reaction conditions sufficient to produce an effluent stream 17 comprising acetic acid. According to embodiments of the present invention, the effluent stream 17 may also include unreacted ethane, unreacted oxygen, carbon dioxide, water, ethylene, methane, nitrogen, argon, carbon monoxide, low concentrations of various impurities and other byproducts, or combinations thereof. In embodiments of the invention, the one or more reactors may be in a series or parallel configuration. Each reactor may be a multi-tubular fixed bed reactor, a fluidized bed reactor, or a combination thereof. The reactor may comprise a multi-tube configuration. The catalyst disposed in each reactor may include a mixed metal oxide comprising MoVNb, MoVNbTe, MoVNbSb, MoVNbW, MoVNbLa, or combinations thereof. The catalyst may also comprise Pd. The catalyst may be supported on alumina, silica, titania, zinc oxide, or a combination thereof. In embodiments of the invention, the catalyst may have a BET surface area of from 10 to 50m for unsupported catalysts²In the case of supported catalysts, the molar ratio may be from 10 to 150m²And/g, and all ranges and values therebetween. The catalyst may have a porosity of 0.05 to 0.6 and all ranges and values therebetween, including ranges of 0.05 to 0.06, 0.06 to 0.07, 0.07 to 0.08, 0.08 to 0.09, 0.09 to 0.1, 0.1 to 0.2, 0.2 to 0.3, 0.3 to 0.4, 0.4 to 0.5, and 0.5 to 0.6.

According to embodiments of the invention, each reactor of the reaction unit 102 may include an inlet and an outlet adapted to receive and release the regeneration gas stream 15, respectively, such that the regeneration gas stream 15 flows through the catalyst in each reactor of the reaction unit 102. In embodiments of the invention, the system 100 may include a regeneration gas heating unit 103 disposed upstream of the inlet for the regeneration gas stream 15. The regeneration gas heating unit 103 may be adapted to heat the regeneration gas stream 15 to a predetermined regeneration temperature. In embodiments of the invention, the regeneration gas stream 15 may be adapted to restore the catalytic activity and selectivity of the catalyst. In embodiments of the invention, the regeneration gas stream 15 is capable of removing hydrocarbon or carbon deposits on the surface of the catalyst and/or reversing the change in oxidation state of the catalyst metal oxide. In embodiments of the invention, the regeneration gas stream 15 may comprise from 2 to 21 mol% oxygen and from 79 to 98 mol% inert gas. The inert gas may include nitrogen, argon, carbon dioxide, or combinations thereof.

According to an embodiment of the invention, each reactor of the reaction unit 102 may include an inlet and an outlet adapted to receive and release the stream of purge gas 16, respectively, such that the stream of purge gas 16 flows through each reactor. In embodiments of the invention, the purge gas stream 16 may be adapted to purge the hydrocarbon (e.g., ethane) in each reactor of the reaction unit 102. In embodiments of the invention, the purge gas stream 16 may comprise nitrogen, argon, CO₂Or a combination thereof. In an embodiment of the invention, the purge gas stream 16 may flow into the reaction unit 102 through the same inlet as the feed stream 11, such that the purge gas stream 16 purges each reactor of the reaction unit 102 and the piping for flowing the feed stream 11 into the reaction unit 102.

In embodiments of the invention, the effluent outlet of the reaction unit 102 may be in fluid communication with the inlet of the effluent cooler 104 such that the effluent stream 17 flows from the reaction unit 102 to the effluent cooler 104. According to an embodiment, the effluent cooler 104 is adapted to cool the effluent stream 17 to produce a cooled effluent stream 18. The cooled effluent stream 18 can comprise at least some condensed acetic acid and/or condensed water. In embodiments of the present invention, the effluent cooler 104 may comprise one or more heat exchangers, one or more quench columns, or a combination thereof.

In embodiments of the invention, the first inlet of the reaction unit 102 may be the same as the inlet adapted to receive the regeneration gas stream 15 and/or the inlet adapted to receive the purge gas stream 16. In embodiments of the invention, the effluent outlet of the reaction unit 102 may be the same as the outlet adapted to release the regeneration gas stream 15 and/or the outlet adapted to release the purge gas stream 16. According to an embodiment of the invention, the regeneration gas heating unit 103 may be the same as the feed heating unit 101.

According to embodiments of the invention, the outlet of the effluent cooler 104 may be in fluid communication with the gas-liquid separator 105 such that the cooled effluent stream 18 flows from the effluent cooler 104 to the gas-liquid separator 105. In embodiments of the invention, the gas-liquid separator 105 may be adapted to separate the cooled effluent stream 18 into a gaseous stream 19 and a liquid stream 20. According to embodiments of the invention, the gaseous stream 19 may comprise carbon dioxide, unreacted ethane, unreacted oxidant, or combinations thereof. The liquid stream 20 can comprise water, acetic acid, or a combination thereof. Exemplary gas-liquid separator 105 may include a flash tank, a cold box, a condenser, an acetic acid scrubber, or combinations thereof.

In embodiments of the invention, the top outlet of the gas-liquid separator 105 may be in fluid communication with the carbon dioxide removal unit 106 such that the gaseous stream 19 flows from the gas-liquid separator 105 to the carbon dioxide removal unit 106. In embodiments of the invention, the carbon dioxide removal unit 106 may be adapted to separate the gaseous stream 19 into a carbon dioxide stream 23 and a recycle stream 22. The recycle stream 22 can comprise unreacted ethane, unreacted oxidant, or a combination thereof. In embodiments of the invention, the carbon dioxide removal unit 106 may include one or more CO₂An absorption column, and one or more for CO₂A regeneration unit for absorbing solution. In embodiments of the invention, the outlet of the carbon dioxide removal unit 106 may be in fluid communication with the inlet of the feed heating unit 101 such that the recycle stream is combined with the feed stream 11 and flows to the feed heating unit 101.

According to embodiments of the invention, the bottom outlet of the gas-liquid separator 105 may be in fluid communication with an inlet of the dewatering unit 107 such that the liquid stream 20 flows from the gas-liquid separator 105 to the dewatering unit 107. In embodiments of the invention, the dehydration unit 107 may be adapted to separate the liquid stream 20 into a water stream 23 and an acetic acid stream 24. In embodiments of the present invention, dehydration unit 107 may include an azeotropic distillation column, a binary distillation column, or a combination thereof. According to embodiments of the invention, the azeotropic distillation column may use ethyl acetate and/or butyl acetate as an entrainer to form an azeotrope with water.

B. Method for using and regenerating a catalyst for the production of acetic acid

A process has been discovered for using and regenerating a catalyst for the production of acetic acid from ethane. The method can improve the production efficiency of acetic acid and reduce the production cost as compared with the conventional method. As shown in fig. 2, an embodiment of the invention includes a process 200 for producing acetic acid from ethane using a catalyst for an extended period of time, and then regenerating the catalyst for additional acetic acid from ethane for an extended period of time. The method 200 may be implemented by the system 100 as shown in fig. 1. According to an embodiment of the invention, as shown in block 201, the method 200 may include flowing (1) the feed gas stream 13 and (2) the oxidant stream 14 to a reaction unit 102 comprising one or more reactors in which a catalyst is disposed to catalyze an ethane oxidation reaction, as shown in block 201. In an embodiment of the invention, the combined stream of the feed gas stream 13 and the oxidant stream 14 (feed stream 11) may be heated in the feed heating unit 101 before they flow to the reaction unit 102. In embodiments of the invention, the combined stream (feed stream 11) may be heated to a temperature of 150 to 450 ℃ and temperatures of all ranges and values therebetween, including ranges of 150 to 165 ℃, 165 to 180 ℃, 180 to 195 ℃, 195 to 210 ℃, 210 to 225 ℃, 225 to 240 ℃, 240 to 255 ℃, 255 to 270 ℃, 270 to 285 ℃, 285 to 300 ℃, 300 to 315 ℃, 315 to 330 ℃, 330 to 345 ℃, 345 to 360 ℃, 360 to 375 ℃, 375 to 390 ℃, 390 to 405 ℃, 405 to 420 ℃, 420 to 435 ℃, and 435 to 450 ℃. In embodiments of the invention, the combined stream (feed stream 11) at block 201 may include oxygen in the range of 0.1 to 50 wt% and all ranges and values therebetween, including ranges of 0.1 to 0.2 wt%, 0.2 to 0.3 wt%, 0.3 to 0.4 wt%, 0.4 to 0.5 wt%, 0.5 to 0.6 wt%, 0.6 to 0.7 wt%, 0.7 to 0.8 wt%, 0.8 to 0.9 wt%, 0.9 to 1.0 wt%, 1.0 to 5.0 wt%, 5.0 to 10 wt%, 10 to 15 wt%, 15 to 20 wt%, 20 to 25 wt%, 25 to 30 wt%, 30 to 35 wt%, 35 to 40 wt%, 40 to 45 wt%, and 45 to 50 wt%. In embodiments of the invention, the catalyst may comprise an oxide of Mo, V, Nb, Pd or combinations thereof. In embodiments of the invention, the catalyst may comprise a mixed metal oxide comprising MoVNb, MoVNbTe, MoVNbSb, MoVNbW, MoVNbLa or combinations thereof. The catalyst may further comprise Pd. According to embodiments of the present invention, the catalyst may be supported on alumina, silica, titania, zinc oxide, or combinations thereof.

According to an embodiment of the invention, as shown in block 202, the process 200 may further include reacting ethane with an oxidant in the presence of a catalyst in the reaction unit 102 to produce an effluent stream 17 comprising acetic acid. In embodiments of the present invention, the effluent stream 17 may also comprise unreacted ethane, unreacted oxidant, carbon dioxide, water, ethylene, methane, nitrogen, argon, or combinations thereof. According to embodiments of the invention, the reaction conditions at block 202 may include reaction temperatures in the range of 150 to 450 ℃ and all ranges and values therebetween, including the ranges of 150 to 165 ℃, 165 to 180 ℃, 180 to 195 ℃, 195 to 210 ℃, 210 to 225 ℃, 225 to 240 ℃, 240 to 255 ℃, 255 to 270 ℃, 270 to 285 ℃, 285 to 300 ℃, 300 to 315 ℃, 315 to 330 ℃, 330 to 345 ℃, 345 to 360 ℃, 360 to 375 ℃, 375 to 390 ℃, 390 to 405 ℃, 405 to 420 ℃, 420 to 435 ℃, and 435 to 450 ℃. The reaction conditions at block 202 may include reaction pressures in the range of 1 to 50 bar and all ranges and values therebetween, including the ranges of 1 to 5 bar, 5 to 10 bar, 10 to 15 bar, 15 to 20 bar, 20 to 25 bar, 25 to 30 bar, 30 to 35 bar, 35 to 40 bar, 40 to 45 bar, and 45 to 50 bar. The reaction conditions at block 202 may further include a temperature of 50 to 50000hr^-1And all ranges and values therebetween, including from 50 to 100hr^-1100 to 200hr^-1200 to 300hr^-1300 to 400hr^-1400 to 500hr^-1500 to 600hr^-1600 to 700hr^-1700 to 800hr^-1800 to 900hr^-1900 to 1000hr^-11000 to 2000hr^-12000 to 3000hr^-13000 to 4000hr^-14000 to 5000hr^-15000 to 6000hr^-16000 to 7000hr^-17000 to 8000hr^-18000 to 9000hr^-19000 to 10000hr^-110000 to 15000hr^-115000 to 20000hr^-120000 to 25000hr^-125000 to 30000hr^-130000 to 35000hr^-135000 to 40000hr^-140000 to 45000hr^-145000-50000 hr^-1The range of (1).

According to embodiments of the invention, the process 200 may further comprise purifying the acetic acid by removing byproducts including carbon dioxide and/or water from the effluent stream 17, as shown in block 203. In embodiments of the invention, the purification at block 203 may include cooling the effluent stream 17 in the effluent cooler 104 to form a cooled effluent stream 18 comprising at least some liquid acetic acid and/or liquid water, as shown in block 204. In embodiments of the invention, the purification at block 203 may also include separating the cooled effluent stream 18 into a gaseous stream 19 and a liquid stream 20 in the gas-liquid separator 105.

In an embodiment of the invention, the liquid-gas separation unit 105 comprises a flash tank. As an alternative to or in addition to the flash tank, the liquid-gas separation unit 105 may include an acetic acid scrubber that uses water to scrub uncondensed water from the cooled effluent stream 18.

In embodiments of the invention, as shown in block 205, the separating at block 206 may further include separating the liquid stream 20 in the dehydration unit 107 to form an acetic acid stream 24 and a water stream 23. In an embodiment of the invention, dehydration unit 107 comprises one or more azeotropic distillation columns. In embodiments of the invention, the entrainer of the azeotropic distillation column may comprise ethyl acetate, butyl acetate, or a combination thereof. As an alternative to, or in addition to, an azeotropic distillation column, dehydration unit 107 may include one or more binary distillation columns.

According to an embodiment of the invention, as shown in block 206, the process 200 may further include separating the gaseous stream 19 in the carbon dioxide removal unit 106 to produce a carbon dioxide stream 21 and a recycle stream 22 comprising unreacted ethane and unreacted oxidant. In embodiments of the invention, the carbon dioxide removal unit 106 may include one or more carbon dioxide absorption towers. According to an embodiment of the invention, as shown in block 207, the method 200 may further include flowing the recycle stream 22 into the feed heating unit 101 such that unreacted ethane and unreacted oxidant are combined with the feed stream 11.

According to an embodiment of the invention, the method 200 further includes stopping the flow of the feed gas stream 13 and the oxidant stream 14 to the reaction unit 102 when the catalyst's ability to catalyze the reaction between ethane and the oxidant decreases by a predetermined percentage, as shown in block 208. In an embodiment of the invention, the catalytic activity of the catalyst decreases by a predetermined percentage every 3 to 6 months or year, depending on the rate of decline of the catalyst. Thus, in embodiments of the invention, the flow of the feed gas stream 13 is stopped every 3 to 6 months or year for the following flushing and regeneration. In embodiments of the invention, the ability of the catalyst to catalyze the reaction between ethane and an oxidant may be defined by the catalyst activity and/or catalyst selectivity. In embodiments of the invention, the predetermined percentage of reduced catalyst capacity used at block 203 may be in the range of 20% to 80%, and all ranges and values therebetween, including the ranges of 20 to 23%, 23 to 26%, 26 to 29%, 29 to 32%, 32 to 35%, 35 to 38%, 38 to 41%, 41 to 44%, 44 to 47%, 47 to 50%, 50 to 53%, 53 to 56%, 56 to 59%, 59 to 62%, 62 to 65%, 65 to 68%, 68 to 71%, 71 to 74%, 74 to 77%, and 77 to 80%. In embodiments of the invention, the fresh catalyst selectivity for the production of acetic acid may be in the range of 20 to 80%, and all ranges and values therebetween, including ranges of 20 to 25%, 25 to 30%, 30 to 35%, 35 to 40%, 40 to 45%, 45 to 50%, 50 to 55%, 55 to 60%, 60 to 65%, 65 to 70%, 70 to 75%, and 75 to 80%.

In embodiments of the invention, the method 200 may further include flushing the feed line to the one or more reactors and the one or more reactors of the reaction unit 102 with a purge gas stream 16 comprising an inert gas, as shown in block 209. In embodiments of the present invention, the inert gas may comprise nitrogen, argon, carbon dioxide, or combinations thereof.

According to an embodiment of the invention, as shown in block 210, the method 200 may further include flowing the regeneration gas stream 15 through one or more reactors of the reaction unit 102 to contact the regeneration gas stream 15 with the catalyst to increase the ability of the catalyst to catalyze the reaction between ethane and the oxidant. In embodiments of the invention, the flow at block 205 may be conducted at a regeneration temperature in the range of 200 to 375 ℃ and all ranges and values therebetween, including regeneration temperatures in the range of 200 to 205 ℃, 205 to 210 ℃, 210 to 215 ℃, 215 to 220 ℃, 220 to 225 ℃, 225 to 230 ℃, 230 to 235 ℃, 235 to 240 ℃, 240 to 245 ℃, 245 to 250 ℃, 250 to 255 ℃, 255 to 260 ℃, 260 to 265 ℃, 265 to 270 ℃, 270 to 275 ℃, 275 to 280 ℃, 280 to 285 ℃, 285 to 290 ℃, 290 to 295 ℃, 295 to 300 ℃, 300 to 305 ℃, 305 to 310 ℃, 310 to 315 ℃, 315 to 320 ℃, 320 to 325 ℃, 325 to 330 ℃, 330 to 335 ℃, 335 to 340 ℃, 340 to 345 ℃, 345 to 350 ℃, 350 to 355 ℃, 355 to 360 ℃, 360 to 365 ℃, 365 to 370 ℃, and 370 ℃ and 370 to 375 ℃. The regeneration temperature is selected such that substantially no liquid water is formed in the reaction unit 102 during the flow at block 210. According to an embodiment of the invention, the temperature in the reaction unit 102 is maintained at least in part by heating the regeneration gas stream 15 via the regeneration gas heating unit 103.

In an embodiment of the invention, the flow at block 210 may be such that the gas hourly space velocity in the reaction unit 102 is in the range of 1000 to 10,000hr^-1Within the range of (1), and all ranges and values therebetween, including 1000 to 2000hr^-12000 to 3000hr^-13000 to 4000hr^-1、4000 to 5000hr^-15000 to 6000hr^-16000 to 7000hr^-17000 to 8000hr^-18000 to 9000hr^-1And 9000 to 10,000hr^-1The range of (1). In embodiments of the invention, the regeneration gas stream may comprise 2 to 21 mol% oxygen, and all ranges and values therebetween, including ranges of 2 to 3 mol%, 3 to 4 mol%, 4 to 5 mol%, 5 to 6 mol%, 6 to 7 mol%, 7 to 8 mol%, 8 to 9 mol%, 9 to 10 mol%, 10 to 11 mol%, 11 to 12 mol%, 12 to 13 mol%, 13 to 14 mol%, 14 to 15 mol%, 15 to 16 mol%, 16 to 17 mol%, 17 to 18 mol%, 18 to 19 mol%, 19 to 20 mol%, and 20 to 21 mol%. According to an embodiment of the invention, the oxygen fraction in the regeneration gas stream is kept at a low level to substantially prevent oxygen from staying in dead zones in the catalyst bed. In an embodiment of the invention, the flow at block 210 may be performed for a duration of 3 to 24 hours. In an embodiment of the present invention, the flow at block 210 may be performed for more than 24 hours. According to an embodiment of the invention, the flow of the regeneration gas stream 15 at block 210 is capable of restoring the activity and/or selectivity of the catalyst to at least 70% of the fresh catalyst (i.e., catalyst that has not been used in the reaction step of block 202). As an alternative to flowing the regeneration gas through the reaction unit 102 to regenerate the catalyst, regeneration of the catalyst may be performed by withdrawing the catalyst from the reaction unit 102 and flowing the regeneration gas stream 15 through the catalyst outside the reaction unit 102.

In an embodiment of the present invention, as shown in block 211, the method 200 includes purging an inert gas to remove oxygen present in the residual regeneration gas in the reactor of the reaction unit 102. Non-limiting examples of purge inert gases may include nitrogen, argon, CO₂And combinations thereof.

According to embodiments of the invention, one or more reactors in the reaction unit 102 may be operated in parallel. Each of the one or more reactors in the reaction unit 102 may repeat blocks 201 through 211 every 3 months to every two years, or preferably every 3 months to every 6 months. In an embodiment of the present invention, the reaction at block 202 is carried out in at least one reactor of the reaction unit 102 at any time while the system 100 is in operation.

Although embodiments of the present invention have been described with reference to the blocks of fig. 2, it should be understood that the operations of the present invention are not limited to the specific blocks and/or the specific order of the blocks shown in fig. 2. Accordingly, embodiments of the invention may use various blocks in a different order than that of FIG. 2 to provide the functionality as described herein.

In the context of the present invention, at least the following 15 embodiments are described. Embodiment 1 is a method of using and regenerating a catalyst for the production of acetic acid from ethane. The process includes flowing (1) a feed gas comprising ethane and (2) an oxidant comprising oxygen into a reactor having disposed therein a catalyst comprising an oxide of MoVNbPd. The process also includes reacting ethane with an oxidant in the presence of a catalyst in a reactor to produce acetic acid. The process further comprises, when the catalyst's ability to catalyze the reaction between ethane and the oxidant decreases by 30% or more, stopping the flow of the feed gas and the oxidant to the reactor and allowing a regeneration gas stream comprising 2 to 21 mol% oxygen to flow at a temperature of 200 to 375 ℃ and for 1000 to 10,000h^-1Is flowed through the reactor to contact the regeneration gas stream with the catalyst to increase the ability of the catalyst to catalyze the reaction between ethane and the oxidant. Embodiment 2 is the method of embodiment 1, further comprising flushing a feed line to the reactor and the reactor with an inert gas prior to flowing the regeneration gas stream. Embodiment 3 is the method of embodiment 2, wherein the inert gas is selected from the group consisting of nitrogen, argon, CO₂And combinations thereof. Embodiment 4 is the method of any of embodiments 1 to 3, wherein the regeneration gas stream flows through the reactor for at least 3 to 24 hours. Embodiment 5 is the method of any one of embodiments 1 to 4, wherein the reactor is maintained at a temperature that prevents the formation of liquid water. Embodiment 6 is the method of any one of embodiments 1 to 5, wherein the regeneration gas stream further comprises nitrogen, carbon dioxide, argon, or a combination thereof. Embodiment 7 is the method of any one of embodiments 1 to 6, wherein flowing the regeneration gas through the reactor is capable of passing the regeneration gas through the reactorThe activity of the catalyst was restored to 70 to 100% of the fresh catalyst. Embodiment 8 is the method of any one of embodiments 1 to 7, further comprising recycling unreacted ethane and/or unreacted oxidant to the reactor. Embodiment 9 is the method of any one of embodiments 1 to 8, wherein the reactor comprises a fixed bed reactor, a fluidized bed reactor, or a combination thereof. Embodiment 10 is the method of any one of embodiments 1 to 9, wherein the catalyst is supported on alumina, silica, titania, zinc oxide, or a combination thereof. Embodiment 11 is the method of any one of embodiments 1 to 10, wherein the reacting is carried out at a temperature of 150 to 450 ℃. Embodiment 12 is the method of any one of embodiments 1 to 11, wherein the reacting is carried out at a pressure of 1 to 50 bar. Embodiment 13 is the method of any one of embodiments 1 to 10, wherein the reacting is between 50 to 50000hr^-1At a gas hourly space velocity of (a). Embodiment 14 is the method of any one of embodiments 1 to 13, wherein the molar ratio of oxygen to ethane flowed into the reactor is in the range of 1:1000 to 1: 1. Embodiment 15 is the method of any one of embodiments 1 to 14, further comprising removing the CO-containing gas by₂And/or water to purify the acetic acid.

Although the embodiments of the present application and their advantages have been described in detail, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the embodiments as defined by the appended claims. Moreover, the scope of the present application is not intended to be limited to the particular embodiments of the process, machine, manufacture, composition of matter, means, methods and steps described in the specification. As one of ordinary skill in the art will readily appreciate from the disclosure set forth above, processes, machines, manufacture, compositions of matter, means, methods, or steps, presently existing or later to be developed that perform substantially the same function or achieve substantially the same result as the corresponding embodiments described herein may be utilized. Accordingly, the appended claims are intended to include within their scope such processes, machines, manufacture, compositions of matter, means, methods, or steps.