System and process for producing alkylene glycol

Abstract

A method for producing alkylene glycols are disclosed. A feed stream comprising an alkylene oxide and water is flowed through to at least one inlet of a reaction unit thereby producing an first outlet stream comprising water, monoalkylene glycol, dialkylene glycol, trialkylene glycol or a combination thereof from the outlet of the reaction unit. The first outlet stream is passed through a first separation unit to produce a second outlet stream comprising water and a third outlet stream comprising monoalkylene glycol, dialkylene glycol, trialkylene glycol or a combination thereof. At least a portion of the third outlet stream is recycled to at least one inlet of the reaction unit.

Description

SYSTEM AND PROCESS FOR PRODUCING ALKYLENE GLYCOLCROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to and the benefit of Indian Provisional Patent Application 202341090218, filed December 30, 2023. The contents of the referenced patent application is incorporated into the present application by reference.FIELD OF INVENTION

[0002] The present invention generally relates to a system and a method for producing alkylene glycols (e.g. ethylene glycols) from alkylene oxide (e.g. ethylene oxide). Specifically, the present invention relates to a system and a process for improving the product distribution of diethylene and triethylene glycols. More specifically, the present invention relates to a system and a process for improving the product distribution of diethylene and triethylene glycols using recycle streams.BACKGROUND OF THE INVENTION

[0003] Alkylene glycols are generally prepared by hydrolysis of alkylene oxide in a plug flow reactor in a non-catalytic pathway. The alkylene oxide (e.g. ethylene oxide) is produced from alkylene (e.g. ethylene) and oxygen over a catalyst consisting of silver supported on alphaalumina, under pressures of 10 bar to 30 bar and temperatures of 200 °C to 300 °C. The hydrolysis reaction is performed by adding a large excess of water, e.g., 15 moles to 30 moles of water per mole of ethylene oxide. The resulting aqueous mixture comprises mostly monoethylene glycol (MEG) in the range of 90 wt.% to 91 wt.% followed by di ethylene glycol (DEG) in the range of 8 wt.% to 9 wt.%, tri ethylene glycol (TEG) in the range of 0.5 wt.% to 1 wt.%, and the remainder being polyethylene glycol (PEG). The hydrolysis reaction is a nucleophilic substitution reaction, in which a ring opening of the ethylene oxide occurs and water serves as the nucleophile. The initially formed monoethylene glycol can also act as a nucleophile, and a mixture of monoethylene glycol, diethylene glycol and higher ethylene glycols is typically formed.

[0004] Alternatively, ethylene glycols can be produced from carbon monoxide, oxygen, and hydrogen. The carbon monoxide and hydrogen are first used to produce methanol. The methanol is then subjected to oxidative carbonylation, using carbon monoxide, to producedimethyl oxalate. Dimethyl oxalate is then converted to ethylene glycol via hydrogenation. However, this method generally requires the production of carbon monoxide from coal to keep the production cost low. Thus, there is a negative environmental impact associated with this method.

[0005] Glycols have continued commercial interest. For example, monoethylene glycol (MEG) is used in antifreeze compositions, as solvents, coolant for engines and as an intermediate product for producing polyester fibers and polyethylene terephthalate (PET), which is used for producing plastic bottles or fibers. Diethylene glycol (DEG) can be used to produce polyurethanes, plasticizers, and organic solvents. Triethylene glycols (TEG) are often used as plasticizers and moisture-retaining agents. Polyethylene glycols (PEG) are used in perfumes, cosmetics, lubricants, and plasticizers.

[0006] Diethylene glycol and triethylene glycol started out as unwanted byproducts during hydrolysis of ethylene oxide for ethylene glycol production but have achieved a sizable market of their own as antifreeze additives, solvents and plasticizers. The market price for all these ethylene glycols varies with time. For example, the market value of MEG may be higher than the price for DEG but at other times the opposite situation is observed. Similarly, the TEG price may be higher than the prices for MEG and DEG, respectively. Also, there is a frequent and continuous change in market demand for these glycols. This requires change in the product distribution at the outlet of the glycol reactor. In conventional plants, there is some flexibility to vary the water to ethylene oxide ratio to change the product distribution; however that scope is limited because of plant design.

[0007] In conventional thermal hydration of ethylene oxide, the diethylene and triethylene glycols are produced in low concentrations compared to monoethylene glycol. So to achieve higher concentration of diethylene and triethylene glycols, these glycols are generally produced in on-purpose glycol plants. However, on-purpose diethylene and triethylene glycol plants require additional capital expenditure designated for producing it. Additionally, on-purpose diethylene and triethylene glycol plants require utilizing purified ethylene oxide in the feed stream, which causes the production cost for triethylene glycol to be high.

[0008] Overall, while the systems and methods of producing diethylene and triethylene glycol exist, the need for improvements in this field persists in light of at least the aforementioned drawbacks with processes for producing di ethylene glycol and triethylene glycol.

[0009] Therefore, one of the objectives of the present invention is to provide a solution that increases the product distribution of diethylene and triethylene glycol in an existing reactor, thereby greatly reducing capital expenditure designated for on-purpose diethylene and tri ethylene glycol production. Another objective of the present invention is to avoid using purified ethylene oxide in the feed stream during the production of diethylene and triethylene glycols.SUMMARY OF THE INVENTION

[0010] Accordingly, the one or more objectives of the invention is achieved by a method for producing alkylene glycol, wherein the method comprises(i) flowing a feed stream comprising an alkylene oxide and water to at least one inlet of a reaction unit;(ii) producing a first outlet stream comprising water, monoalkylene glycol, dialkylene glycol, trialkylene glycol or a combination thereof from the outlet of the reaction unit;(iii) passing the first outlet stream through a first separation unit to produce a second outlet stream comprising water and a third outlet stream comprising monoalkylene glycol, dialkylene glycol, trialkylene glycol or a combination thereof;(iv) recycling a portion of the third outlet stream to at least one inlet of the reaction unit; and(v) recycling the second outlet stream comprising water to at least one inlet of the reaction unit; wherein the feed stream comprises water to alkylene oxide molar ratio in a range of 15: 1 to 27 : 1 ; and wherein the recycling portion of the third outlet stream is in the range of from 0.1% to 35% of the third outlet stream.

[0011] In some embodiments, the third outlet stream is separated in a second separation unit to produce a fourth outlet stream comprising monoalkylene glycol and a fifth outlet stream comprising dialkylene glycol and tri alkylene glycol; at least a portion of the fourth outlet stream is recycled to at least one inlet of the reaction unit; and at least a portion of the fifth outlet stream is recycled to at least one inlet of the reaction unit.

[0012] In other embodiments, prior to separating the fifth outlet stream in the third separation unit, at least a portion of the fifth outlet stream is recycled to at least one inlet of the reaction unit.

[0013] Yet another embodiment of the invention relates to mixing at least a portion of the fourth outlet stream, at least a portion of the fifth outlet stream, at least a portion of the sixth outlet stream or a combination thereof, with at least a portion of the third outlet stream to produce an eighth outlet stream; and recycling at least a portion of the eighth outlet stream to at least one inlet of the reaction unit.

[0014] Other objects, features and advantages of the invention will become apparent from the following figures, detailed description, and examples. It should be understood, however, that the figures, detailed description, and examples, while indicating specific embodiments of the invention, are given by way of illustration only and are not meant to be limiting. Additionally, 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 further embodiments, features from specific embodiments may be combined with features from other embodiments. For example, features from some specific embodiments 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.

[0015] The following includes definitions of various terms, expressions and phrases used throughout this specification.

[0016] The use of the words “a” or “an” when used in conjunction with the term “comprising,” “including,” “containing,” or “having” in the claims or the specification may mean “one,” but it is also consistent with 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 “comprise” and “comprises”), “having” (and any form of having, such as “have” and “has”), “including” (and any form of including, such as “includes” and “include”) or “containing” (and any form of containing, such as “contains” and “contain”) are inclusive or open-ended and do not exclude additional, unrecited elements or method steps. The method of the invention can “comprise,” “consist essentially of,” or “consist of’ particular ingredients, components, compositions, etc., disclosed throughout the specification.

[0017] The terms “about” or “approximately” are defined as being close to as understood by one of ordinary skill in the art. In one non-limiting embodiment the terms are defined to be within 10%, preferably, within 5%, more preferably, within 1%, and most preferably, within 0.5%.

[0018] For the purposes of this disclosure, “X, Y, and / or Z” can be construed as X only, Y only, Z only, or any combination of two or more items X, Y, and Z (e.g., XYZ, XY, XZ, YZ).

[0019] The terms “wt.%”, “vol.%” or “mol.%” refers to a weight, volume, or molar percentage of a component, respectively, based on the total weight, the total volume, or the total moles of material that includes the component. In a non-limiting example, 10 moles of component in 100 moles of the material is 10 mol.% of component.

[0020] The term “substantially” and its variations are defined to include ranges within 10%, within 5%, within 1%, or within 0.5%.

[0021] The terms “inhibiting” or “reducing” or “preventing” or “avoiding” or any variation of these terms, when used in the claims and / or the specification, includes any measurable decrease or complete inhibition to achieve a desired result.

[0022] The term “effective,” as that term is used in the specification and / or claims, means adequate to accomplish a desired, expected, or intended result.

[0023] The term “primarily,” as that term is used in the specification and / or claims, means greater than any of 50 wt.%, 50 mol.%, and 50 vol.%. For example, “primarily” may include 50.1 wt.% to 100 wt.% and all values and ranges therebetween, 50.1 mol.% to 100 mol.% and all values and ranges therebetween, or 50.1 vol.% to 100 vol.% and all values and ranges therebetween.

[0024] The term “at least a portion” as used throughout this disclosure with regard to any product stream means > 0.1%, preferably from 0.1% to 90%, more preferably from 0.1% to 50%, even more preferably from 0.1% to 35% of the stream.BRIEF DESCRIPTION OF THE DRAWINGS

[0025] For a more complete understanding, reference is now made to the following descriptions taken in conjunction with the accompanying drawings, in which:

[0026] FIG. 1 shows a schematic diagram of a system for producing alkylene glycol in accordance with an embodiment of the present invention involving a reaction unit coupled to separation units for recovery of one or more desired products and recycling a portion thereof to at least one inlet of the reaction unit.

[0027] FIG. 2 shows a schematic flowchart of a method of producing alkylene glycol in accordance with an embodiment of the present invention.DETAILED DESCRIPTION OF THE INVENTION

[0028] Conventionally, ethylene oxide is produced via direct oxidation of ethylene in a reactor which upon thermal hydration produces monoethylene glycol, diethylene glycol, triethylene glycol and polyethylene glycols. During thermal hydration of ethylene oxide, the diethylene and triethylene glycols are produced in low concentration compared to monoethylene glycol. Due to the frequent and continuous change in market demand for these glycols there is a need for flexibility in the product distribution during the production of ethylene glycols without additional capital expenditure. The present invention provides a solution to at least some of the problems. The solution is premised on a method of producing ethylene glycols by flowing a feed stream comprising an ethylene oxide and water to at least one inlet of a reaction unit (reference to a reaction unit refers to a thermal hydration reaction unit in presence of a catalyst or without catalyst); producing an first outlet stream comprising water, monoethylene glycol, diethylene glycol, triethylene glycol or a combination thereof from the outlet of the reaction unit; passing the first outlet stream through a first separation unit (separation unit generally includes a distillation unit, evaporation unit, a drying unit, a separation column, reboilers, a multi-effect evaporator or a combinations thereof) to produce a second outlet stream comprising water and optionally monoalkylene glycol from 0.01 wt.% to 5 wt.% and a third outlet stream comprising monoethylene glycol, diethylene glycol, triethylene glycol or a combination thereof; and recycling at least a portion of the third outlet stream to at least one inlet of the reaction unit. The method can be beneficial when using an existing system for ethylene oxide thermal hydration and thereby is capable of increasing the production rate of diethylene glycol and triethylene glycol compared to conventional methods, and eliminating additional capital expenditure compared to known on-purpose di ethylene and tri ethylene glycol production methods. Additionally, the disclosed system and method do not require purified ethylene oxide in the feed stream, thereby the cost of obtaining such purified product isavoided. The disclosed system and method are configured to keep production capacity of monoethylene glycol nearly the same while increasing the diethylene and triethylene glycol production rates, resulting in a minimized effect on monoethylene glycol production. These and other non-limiting aspects of the present invention are discussed in further detail in the following sections.A. System for Producing Alkylene Glycols

[0029] In embodiments of the invention, a system for producing ethylene glycol can include a thermal hydration reaction unit and one or more separation units. With reference to FIG. 1, a schematic diagram is shown of system 100 for producing alkylene glycols.

[0030] In embodiments of the invention, system 100 comprises a reaction unit 101 configured to receive (1) a first feed stream 11 comprising water and an alkylene oxide, and / or (2) a second feed stream 12 comprising a monoalkylene glycol, a dialkylene glycol, or a combination thereof. In embodiments of the invention, the alkylene oxide can include ethylene oxide and / or propylene oxide. The dialkylene glycol can include diethylene glycol and / or dipropylene glycol. In embodiments of the invention, feed stream 11 has a water-to-ethylene oxide molar ratio in a range of 15 : 1 to 27: 1 and all ranges and values therebetween including ranges of 15 : 1 to 16:1, 16:1 to 17:1, 17:1 to 18:1, 18:1 to 19:1, 19:1 to 20:1,20:1 to 21:1, 21:1 to 22:1, 22:1 to 23:1, 23:1 to 24:1, 24:1 to 25:1, 25:1 to 26:1, 26:1 to 27:1, 15:1 to 17:1, 17:1 to 19:1, 19:1 to 21:1, 21:1 to 23:1, 23:1 to 25:1, 25:1 to 27:1, 15:1 to 18:1, 18:1 to 21:1, 21:1 to 24:1, 24:1 to 27:1, 15:1 to 19:1, 19:1 to 22:1, 22:1 to 25:1, 15:1 to 20:1, 20:1 to 25:1, 15:1 to 21:1, 21:1 to 26:1, 15:1 to 22:1, and 22:1 to 27:1. Although portions of both first feed stream 11 and second feed stream 12 may comprise one or more streams recycled from other portions of system 100 as further described herein, it is to be understood that both of said streams may include portions or inputs external to system 100.

[0031] According to embodiments of the invention, reaction unit 101 is designed for the reaction of water with the alkylene oxide to produce a mixture of a monoalkylene glycol, a dialkylene glycol, a trialkylene glycol, and heavy alkylene glycols such as polyalkylene glycols. In embodiments of the invention, reaction unit 101 is further configured to subject first feed stream 11 and second feed stream 12 to reaction conditions sufficient to react the alkylene oxide with the monoalkylene glycol, and / or the dialkylene glycol or a combination thereof to produce additional amounts of dialkylene glycol, trialkylene glycol, and small amounts ofheavy alkylene glycols. In an aspect, the flow rate of second feed stream 12 is less than 50%, or less than 25%, or less than 10%, or less than 5%, or less than 2% of the flow rate of first feed stream 11. The output of reaction unit 101 is a first outlet stream 13 comprising water, monoalkylene glycol, dialkylene glycol, trialkylene glycol, and small amounts of heavy alkylene glycols. In embodiments of the invention, the trialkylene glycol includes triethylene glycol, the dialkylene glycol includes diethylene glycol, and the monoalkylene glycol includes monoethylene glycol. Reaction unit 101, which may comprise an ethylene glycol synthesis reaction unit, may include a thermal hydration reactor. The thermal hydration reactor may include substantially no catalyst or no catalyst.

[0032] According to embodiments of the invention, an outlet of reaction unit 101 is in fluid communication with an inlet of a first separation unit 102 such that first outlet stream 13 flows from reaction unit 101 to the first separation unit 102. In embodiments of the invention, first separation unit 102 is configured to separate first outlet stream 13 to produce a second outlet stream 14 comprising primarily water and optionally monoalkylene glycol from 0.01 wt.% to 5 wt.%, and a third outlet stream 15 comprising the monoalkylene glycol, the dialkylene glycol, the trialkylene glycol, and small amounts of heavy alkylene glycols. In embodiments of the invention, an outlet from the first separation unit 102 is in fluid communication with an inlet of a second separation unit 103 such that the second separation unit 103 is configured to separate the third outlet stream 15 to produce a fourth outlet stream 16 comprising primarily the monoalkylene glycol, and a fifth outlet stream 17 comprising the dialkylene glycol, the trialkylene glycol, and small amounts of heavy alkylene glycols. In further embodiments of the invention, an outlet from the second separation unit 103 is in fluid communication with an inlet of a third separation unit 104 such that the third separation unit 104 is configured to separate the fifth outlet stream 17 to produce a sixth outlet stream 18 comprising primarily the dialkylene glycol and a seventh outlet stream 19 comprising the trialkylene glycol and small amounts of heavy alkylene glycols.

[0033] As previously stated, reaction unit 101 is configured to react water with alkylene oxide to produce a mixture of monoalkylene glycol, dialkylene glycol, trialkylene glycol, and small amounts of heavy alkylene glycols. In embodiments of the invention, however, reaction unit 101 is further configured to concurrently use first feed stream 11 and at least a portion of third outlet stream 15, via a line 20, to reaction conditions sufficient to react with the alkylene oxide and to produce additional amounts of dialkylene glycol, and trialkylene glycol. Theseadditional amounts of glycols are produced because line 20 includes a higher concentration of glycols, as line 20 has a similar or identical composition as third outlet stream 15. In an aspect, the flow rate of line 20 is less than 50%, or less than 25%, or less than 10%, or less than 5%, or less than 2% of the flow rate of first feed inlet stream 11.

[0034] In embodiments of the invention, reaction unit 101 is further configured to subject first feed stream 11 and at least a portion of fourth outlet stream 16, via line 22, to reaction conditions sufficient to react with alkylene oxide to produce dialkylene glycol, trialkylene glycol, and small amounts of heavy alkylene glycols. These additional amounts of glycols are produced because line 22 includes a higher concentration of glycols, as line 22 has a similar or identical composition as fourth outlet stream 16. In an aspect, the flow rate of line 22 is less than 50%, or less than 25%, or less than 10%, or less than 5%, or less than 2% of the flow rate of first feed inlet stream 11.

[0035] In embodiments of the invention, reaction unit 101 is further configured to subject first feed stream 11 and at least a portion of fifth outlet stream 17, via a line 21, to reaction conditions sufficient to react with and alkylene oxide to produce additional amounts of dialkylene glycol, trialkylene glycol, and small amounts of heavy alkylene glycols. These additional amounts of glycols are produced because line 21 includes a higher concentration of glycols, as line 21 has a similar or identical composition as fifth outlet stream 17. In an aspect, the flow rate of line 21 is less than 50%, or less than 25%, or less than 10%, or less than 5%, or less than 2% of the flow rate of first inlet feed stream 11.

[0036] In the embodiments of the invention, reaction unit 101 is further configured to subject first feed stream 11 and at least a portion of sixth outlet stream 18, via line 23, to reaction conditions sufficient to react with alkylene oxide to produce and trialkylene glycol. These additional amounts of glycols are produced because line 23 includes a higher concentration of glycols, as line 23 has a similar or identical composition as sixth outlet stream 18. In an aspect, the flow rate of line 23 is less than 50%, or less than 25%, or less than 10%, or less than 5%, or less than 2% of the flow rate offirst feed stream 11.

[0037] Yet another embodiment of the invention relates to mixing at least a portion of the fourth outlet stream 16 or at least a portion of the fifth outlet stream 17 or at least a portion of the sixth outlet stream 18 or a combination thereof, with the third outlet stream 15 to produce an eighth outlet stream and recycling at least a portion of the eighth outlet stream via a line 20 to at leastone inlet of the reaction unit 101 which is further configure to subject first feed stream 11 to reaction conditions sufficient to react with the water and alkylene oxide to produce additional amounts of dialkylene glycol, trialkylene glycol, and small amounts of heavy alkylene glycols. These additional amounts of glycols are produced because line 20 includes a higher concentration of glycols, as line 20 has a similar or identical composition as that of fourth outlet stream 16 or fifth outlet stream 17 or the sixth outlet stream 18 or combinations thereof. In an aspect, the flow rate of line 20 is less than 50%, or less than 25%, or less than 10%, or less than 5%, or less than 2% of the flow rate of first inlet feed stream 11.

[0038] In embodiments of the invention, first separation unit 102 can include an evaporation unit, a drying unit, a separation column, reboilers or combinations thereof. The evaporation unit may be configured to evaporate water from first outlet stream 13 to such that third outlet stream 15 has substantially all water removed therefrom. The evaporation unit may include tray columns, packed columns, and columns with a combination of trays and packing. The dewatered effluent stream from the evaporation unit can include 5 to 30 wt. % water. The drying unit may be configured to further remove water from the de-watered third outlet stream 15 to form a dried effluent stream. The drying unit can include tray columns, packed columns, and columns with a combination of trays and packing. The dried effluent stream can include less than 1 wt. % water. In embodiments of the invention second outlet stream 14, comprising water and optionally monoalkylene glycol from 0.01 wt.% to 5 wt.%, is recycled back to reaction unit 101. As previously described, an outlet of the first separation unit 102 is in fluid communication with an inlet of reaction unit 101 (shown in FIG. 1, for example, as being combined with second feed stream 12) such that at least a portion of third outlet stream 15 is recycled back to reaction unit 101, as indicated by line 20.

[0039] According to embodiments of the invention, second separation unit 103 includes a separation column. In embodiments of the invention, second separation unit 103 includes one or more distillation columns. In embodiments of the invention, an outlet of the second separation unit 103 is in fluid communication with an inlet of reaction unit 101 (shown in FIG. 1, for example, as being combined with second feed stream 12) such that at least a portion of fourth outlet stream 16 is recycled back to reaction unit 101, as indicated by line 22. In embodiments of the invention, another outlet of the second separation unit 103 is in fluid communication with an inlet of reaction unit 101 (shown in FIG. 1, for example, as beingcombined with second feed stream 12) such that at least a portion of fifth outlet stream 17 is recycled back to reaction unit 101, as indicated by line 21.

[0040] According to embodiments of the invention, third separation unit 104 includes a separation column and one or more distillation columns. In embodiments of the invention, an outlet of the third separation unit 104 is in fluid communication with an inlet of reaction unit 101 (shown in FIG. 1, for example, as being combined with second feed stream 12) such that at least a portion of sixth outlet stream 18 is recycled back to reaction unit 101, as indicated by line 23.

[0041] In embodiments of the invention, portions of one or more of the third outlet stream 15, fourth outlet stream 16, fifth outlet stream 17, and sixth outlet stream 18, are recycled as input(s) to reaction unit 101. The specific portions of each of said outlet streams that are recycled may be varied as to obtain desired proportions of monoalkylene glycol, dialkylene glycol, and trialkylene glycol. The recycled portions of the third outlet stream, the fourth outlet stream, the fifth outlet stream, and the sixth outlet stream (disclosed herein as lines 20, 22, 21, and 23, respectively) are in the range of from 0.1% to 35% of their respective outlet streams and all ranges and values therebetween including ranges of 0.1% to 34%, 0.1% to 32%, 0.1% to 30%, 0.1% to 29%, 0.1% to 28%, 0.1% to 26%, 0.1% to 24%, 0.1% to 22%, 0.1% to 20%, 0.1% to 18%, 0.1% to 16%, 0.1% to 14%, 0.1% to 12%, 1% to 35%, 1% to 34%, 1% to 32%, 1% to 30%, 1% to 29%, 1% to 28%, 1% to 26%, 1% to 24%, 2% to 35%, 2% to 34%, 2% to 32%, 2% to 30%, 2% to 29%, 2% to 28%, 2% to 26%, 2% to 24%, 2% to 22%, 2% to 20%, 2% to 18%, 3% to 15%, 3% to 13%, 3% to 12%, 3% to 31%, 3% to 30%, 3% to 29%, 3% to 28%, 4% to 35, 4 to 33%, 4% to 32%, 4% to 31%, 4% to 30%, 4% to 29%, 4% to 28%, 5% to 35%, 5% to 32%, 5% to 29%, 5% to 28%, 5.2% to 35%, 5.2% to 33%, 5.2% to 32%, 5.2% to 30%, 5.2% to 29%, 5.2% to 28%.B. Method for Producing Alkylene Glycols

[0042] A method of producing additional dialkylene and trialkylene glycol has been discovered. The method is capable of increasing production rates of dialkylene glycol and trialkylene glycol via thermal hydration of an alkylene oxide with minimum additional capital expenditure, compared to conventional methods. As shown in FIG. 2, embodiments of the invention include method 200 for producing a dialkylene glycol (e.g., diethylene glycol) andtrialkylene glycol (e.g., triethylene glycol). As a non-limiting example, method 200 may be implemented by system 100, as shown in FIG. 1 and described above.

[0043] According to embodiments of the invention, as shown in block 201, method 200 includes flowing a first feed stream 11 comprising an alkylene oxide and water, to react in a reaction unit 101 to produce a first outlet stream 13 comprising water, a monoalkylene glycol, a di ethylene glycol, a trialkylene glycol and small amounts of heavy alkylene glycols. In embodiments of the invention, a second feed stream 12 includes 80 to 100 wt. % monoalkylene glycol or 0 wt.% to 100 wt.% di ethylene glycol or combinations thereof and all ranges and values therebetween including ranges of 80 wt.% to 98 wt.%, 80 wt.% to 96 wt.%, 80 wt.% to 94 wt.%, 80 wt.% to 92 wt.%, 80 wt.% to 90 wt.%, 80 wt.% to 88 wt.%, 80 wt.% to 86 wt.%, 80 wt.% to 84 wt.%, 80 wt.% to 82 wt.%, 82 wt.% to 100 wt.% 82 wt.% to 98 wt.%, 82 wt.% to 96 wt.%, 82 wt.% to 94 wt.%, 82 wt.% to 92 wt.%, 82 wt.% to 90 wt.%, 82 wt.% to 88 wt.%, 82 wt.% to 86 wt.%, 84 wt.% to 100 wt.%, .84 wt.% to 98 wt.%, 84 wt.% to 96 wt.%, 84 wt.% to 94 wt.%, 84 wt.% to 92 wt.%, 84 wt.% to 90 wt.%, 84 wt.% to 88 wt.%, 84 wt.% to 86 wt.%, 86 wt.% to 100 wt.%, 86 wt.% to 98 wt.%, 86 wt.% to 96 wt.%, 86 wt.% to 94 wt.%, 86 wt.% to 92 wt.%, 86 wt.% to 90 wt.%, 0 wt.% to 20 wt.%, 0 wt.% to 18 wt.%, 0 wt.% to 16 wt.%, 0 wt.% to 14 wt.%, 0 wt.% to 12 wt.%, 0 wt.% to 10 wt.%, 0 wt.% to 8 wt.%, 0 wt.% to 6 wt.%, 0 wt.% to 4 wt.%, 0 wt.% to 2 wt.%, 2 wt.% to 20 wt.%, 2 wt.% to 18 wt.%, 2 wt.% to 16 wt.%, 2 wt.% to 14 wt.%, 2 wt.% to 12 wt.%, 2 wt.% to 10 wt.%, 2 wt.% to 8 wt.%, 2 wt.% to 6 wt.%, 2 wt.% to 4 wt.%, 2 wt.% to 3 wt.%, 4 wt.% to 20 wt.%, 4 wt.% to 18 wt.%, 4 wt.% to 16 wt.%, 4 wt.% to 14 wt.%, 4 wt.% to 12 wt.%, 4 wt.% to 10 wt.%, 4 wt.% to 8 wt.%, 4 wt.% to 6 wt.%, 4 wt.% to 5 wt.%. First feed stream 11 may comprise 87 wt.% to 93 wt.% water and 7 wt.% to 13 wt. % ethylene oxide. In embodiments of the invention, at block 201, first feed stream 11 and / or second feed stream 12 flow into reaction unit 101 in a volumetric ratio within a range of 10: 1 to 20000: 1 and all ranges and values therebetween. In embodiments of the invention, first feed stream 11 and second feed stream 12 may be combined before being flowed into reaction unit 101. In embodiments of the invention, as shown in block 201, the molar ratio between alkylene oxide and water in the first feed stream is in a range of 15 : 1 to 27: 1 all ranges and values therebetween.

[0044] According to embodiments of the invention, as shown in block 202, method 200 includes reacting, in reaction unit 101, alkylene oxide and water from first feed stream 11 to produce alkylene glycols including monoalkylene glycol, dialkylene glycol, trialkylene glycol,small amounts of heavy alkylene glycols, or combinations thereof. In embodiments of the invention, the alkylene oxide is ethylene oxide, and the alkylene glycols include monoethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycols or combinations thereof.

[0045] Reaction conditions in reaction unit 101 at block 202 can include a reaction temperature of 120 °C to 250 °C and all ranges and values therebetween including ranges of 120 °C to 225 °C, 120 °C to 200 °C, 120 °C to 180 °C, 120 °C to 160 °C, 120 °C to 140 °C, 130 °C to 225°C, 130 °C to 200 °C, 130 °C to 190 °C, 130 °C to 180 °C, 130 °C to 170 °C, 130 °C to 160°C, 130 °C to 140 °C, 140 °C to 225 °C, 140 °C to 200 °C, 140 °C to 180 °C, 140 °C to 160°C, 140 °C to 150 °C, 150 °C to 160 °C, 160 °C to 170 °C, 170 °C to 180 °C, 180 °C to 190°C, 190 °C to 200 °C, 200 °C to 210 °C, 210 °C to 220 °C, 220 °C to 230 °C, 230 °C to 240°C, and 240 °C to 250 °C. The reaction conditions in reaction unit 101 at block 202 can include a residence time from 0.1 minute to 30 minutes, preferably 0.5 minute to 30 minutes, more preferably 1 minute to 30 minutes. In embodiments of the invention, at block 202, the reaction conditions in reaction unit 101 can include a reaction pressure of 15 bar to 40 bar and all ranges and values therebetween. In embodiments of the invention, the reacting at block 202 is substantially non-catalytic or non-catalytic.

[0046] According to embodiments of the invention, as shown in block 203, method 200 includes reacting, in the reaction unit 101, the monoalkylene glycol, the dialkylene glycol or combinations thereof from second feed stream 12 and the alkylene oxide from feed stream 11 to produce dialkylene glycol and trialkylene glycol. In embodiments of the invention, the dialkylene glycol includes diethylene glycol and the trialkylene glycol includes triethylene glycol. In embodiments of invention, reacting at blocks 202 and 203 are conducted concurrently in the same reaction unit 101. In embodiments of the invention, the reaction mixture in reaction unit 101 can form a first outlet stream 13 comprising water, monoalkylene glycol, dialkylene glycol, and trialkylene glycol. The first outlet stream 13 may further include heavy alkylene glycols. In embodiments of the invention, the first outlet stream 13 includes 10 wt.% to 25 wt. % monoethylene glycol, 0.5 wt.% to 5 wt. % diethylene glycol, 0.01 wt.% to 0.5 wt. % triethylene glycol, and 75 wt.% to 90 wt. % water.

[0047] According to embodiments of the invention, as shown in block 204, method 200 includes separating the first outlet stream 13, in a first separation unit 102, into a second outlet stream 14 comprising water, and optionally monoalkylene glycol from 0.01 wt.% to 5 wt.%and a third outlet stream 15 comprising monoalkylene glycol, dialkylene glycol, trialkylene glycol and small amounts of heavy alkylene glycols. In embodiments of the invention, monoalkylene glycol, dialkylene glycol and trialkylene glycol in stream 15 is monoalkylene glycol comprising monoethylene glycol in a range of 80 wt.% to 95 wt.%, dialkylene glycol comprising diethylene glycol in a range of 4.9 wt.% to 18 wt.%, and trialkylene glycol comprising triethylene glycol in a range of 0.1 wt.% to 2 wt.%.

[0048] In embodiments of the invention, as shown in block 205, method 200 may include recycling a portion of third outlet stream 15 to at least one inlet of reaction unit 101. The recycled portion of the third outlet stream 15 in a range of 0.1% to 35% of the third outlet stream and all ranges and values therebetween. In embodiments of the invention, as shown in block 206, method 200 includes reacting, in the reaction unit 101, the recycled portion of third outlet stream 15 and the alkylene oxide from feed stream 11 to produce additional dialkylene glycol and trialkylene glycol. In embodiments of invention, reacting at blocks 202 and 206 are conducted concurrently in the same reaction unit 101. Reaction conditions in reaction unit 101 at block 206 can include a reaction temperature of 120 °C to 250 °C and all ranges and values therebetween.

[0049] In embodiments of the invention, as shown in block 207, method 200 includes separating third outlet stream 15, in a second separation unit 103, into a fourth outlet stream 16 comprising monoalkylene glycol and a fifth outlet stream 17 comprising dialkylene glycol, trialkylene glycol, and small amounts of heavy alkylene glycols. In embodiments of the invention, fourth outlet stream 16 comprises monoethylene glycol in a range of 99 wt.% to 100 wt.%, and fifth outlet stream 17 comprises di ethylene glycol in a range of 90 wt.% to 98 wt.%, tri ethylene glycol in a range of 2 wt.% to 10 wt.%, and all ranges and values therebetween.

[0050] In embodiments of the invention, as shown in block 208, method 200 may include recycling a portion of fourth outlet stream 16 to at least one inlet of reaction unit 101. The recycled portion of fourth outlet stream 16 is in a range of 0.1% to 35% of the fourth outlet stream and all ranges and values therebetween. In embodiments of the invention, as shown in block 209, method 200 may include reacting, in the reaction unit 101, the monoalkylene glycol from fourth outlet stream 16 and the alkylene oxide from first feed stream 11 to produce additional dialkylene glycol and / or trialkylene glycol. In embodiments of invention, the reacting at blocks 202 and 209 are conducted concurrently in the same reaction unit 101.Reaction conditions in reaction unit 101 at block 209 can include a reaction temperature of 120 °C to 250 °C and all ranges and values therebetween.

[0051] In embodiments of the invention, as shown in block 210, method 200 may include recycling a portion of the dialkylene glycol and trialkylene glycol from fifth outlet stream 17 to at least one inlet of reaction unit 101. The recycled portion of fifth outlet stream 17 is in a range of 0.1% to 35% of the fifth outlet stream and all ranges and values therebetween. In embodiments of the invention, as shown in block 211, method 200 may include reacting, in reaction unit 101, the dialkylene glycol and trialkylene glycol from the recycled portion of fifth outlet stream 17 and the alkylene oxide from feed stream 11 to produce additional dialkylene glycol and / or trialkylene glycol. In embodiments of invention, reacting at blocks 202 and 211 are conducted concurrently in the same reaction unit 101. Reaction conditions in reaction unit 101 at block 211 can include a reaction temperature of 120 °C to 250 °C and all ranges and values therebetween it.

[0052] In embodiments of the invention, as shown in block 212, method 200 includes separating fifth outlet stream 17, in a third separation unit 104, to a sixth outlet stream 18 comprising dialkylene glycol and a seventh outlet stream 19 comprising trialkylene glycol, and small amounts of heavy alkylene glycols. In embodiments of the invention, sixth outlet stream 18 comprises di ethylene glycol in a range of 99 wt.% to 100 wt.% with the remainder being trialkylene glycol. Seventh outlet stream 19 comprises triethylene glycol in a range of 90 wt.% to 98 wt.% and all ranges and values therebetween, with the remainder of the seventh outlet stream comprising small amounts of heavy alkylene glycols. In embodiments of the invention, as shown in block 213, method 200 may include recycling a portion of sixth outlet stream 18 to at least one inlet of reaction unit 101. The recycled portion of sixth outlet stream 18 is in a range of 0.1% to 35% of sixth outlet stream 18 and all ranges and values therebetween. In embodiments of the invention, as shown in block 214, method 200 may include reacting, in reaction unit 101, the dialkylene glycol from the recycled portion of sixth outlet stream 18 and the alkylene oxide from first feed stream 11 to produce additional trialkylene glycol. In embodiments of invention, the reacting at blocks 202 and 214 are conducted concurrently in the same reaction unit 101. Reaction conditions in reaction unit 101 at block 214 can include a reaction temperature of 120 °C to 250 °C and all ranges and values therebetween.EXAMPLES(Simulations on Ethylene Glycol Production)Example 1: Introduce Mono Ethylene Glycol in inlet of EG reaction unit:

[0053] Simulations of ethylene glycol production processes in the system of the present invention and in a conventional production system were run on the Aspen Plus simulation platform. Simulations were run with the flow rate of monoethylene glycol feeding into the thermal hydration reactor being set to 5000 kg / hr, 10000 kg / hr, and 15000 kg / hr. The reaction conditions included a reaction temperature of 150 °C and a residence time from 0.1 minute to 7 minutes, preferably 0.5 minute to 7 minutes, more preferably 1 minute to 7 minutes. The results are shown in Table 1, Table 2 and Table 3. The results show that feeding monoethylene glycol along with water and ethylene oxide into the thermal hydration reactor is capable of increasing the diethylene and triethylene glycol production rate.Table 1. Simulation results for Diethylene and Triethylene glycol at water to EO molar ratio of 25: 1Table 2. Simulation results for Diethylene and Tri ethylene glycol at water to EO molar ratio of 18: 1Table 3. Simulation results of recycling Monoethylene Glycol in the range of 5% to 25%Example 2: Introduce Mono Ethylene Glycol and Diethylene Glycol in inlet of EG reaction unit:

[0054] Simulations of ethylene glycol production processes in the system of the present invention and in a conventional production system were run on the Aspen Plus simulation platform. Simulations were run with the flow rate of monoethylene glycol feeding into the thermal hydration reactor being set to 5000 kg / hr, 10000 kg / hr, and 15000 kg / hr. The reaction conditions included a reaction temperature of 150 °C and a residence time from 0.1 minute to7 minutes, preferably 0.5 minute to 7 minutes, more preferably 1 minute to 7 minutes. The results are shown in Table 4, Table 5 and Table 6. The results show that feeding monoethylene glycol along with water and ethylene oxide into the thermal hydration reactor is capable of increasing the diethylene and triethylene glycol production rate. Table 4. Simulation results for Diethylene and Triethylene glycol at water to EO molar ratio of25: 1Table 5. Simulation results for Diethylene and Tri ethylene glycol at water to EO molar ratio of 18: 1Table 6. Simulation results of recycling Monoethylene Glycol in the range of 5% to 25% and DEG in the range of 5% to 20%

[0055] The systems and processes described herein can also include various equipment that is not shown and is known to one of skill in the art of chemical processing. For example, controllers, piping, computers, valves, pumps, heaters, thermocouples, pressure indicators, mixers, heat exchangers, and the like may not be shown.

[0056] In the context of the present invention, at least the following 18 embodiments are described. Embodiment 1 is a method of producing an alkylene glycol. The method includes flowing (i) a first feed stream comprising alkylene oxide and water and a second feed stream comprising monoalkylene glycol or dialkylene glycol or a combination thereof into a reaction unit.. The method further includes reacting, in the reaction unit, a second stream comprising monoalkylene glycol, or dialkylene glycol or a combination thereof with the first feed under reaction conditions sufficient to produce additional dialkylene glycol and trialkylene glycol.Embodiment 2 is the method of embodiment 1, wherein the reacting step produces a first outlet stream from the reaction unit comprising 10 to 25 wt.% monoalkylene glycol, 0.5 to 5 wt.% dialkylene glycol, 0.01 to 0.5 wt.% trialkylene glycol. Embodiment 3 is the method of any ofembodiments 1 to 2, further including separating the first outlet stream to produce a third outlet stream comprising monoalkylene glycol in the range of 80 to 95 wt.%, dialkylene glycol in the range of 4.9 to 18 wt.%, and trialkylene glycol in the range of 0.1 to 2 wt.%. Embodiment 4 is the method of any of the embodiments 1 to 3 at least a portion of the third outlet stream product stream is recycled into the reaction unit. Embodiment 5 is the method of any of the embodiments 1 to 4, wherein the separating step of the third outlet further produces a monoalkylene glycol stream and a dialkylene glycol, trialkylene glycol product stream. Embodiment 6 is the method of any of the embodiments 1 to 5 at least a portion of the monoalkylene glycol product stream is recycled into the reaction unit. Embodiment 7 is the method of any of the embodiments 1 to 6, at least a portion of the dialkylene glycol, and trialkylene product stream is recycled into the reaction unit. Embodiment 8 is the method of any of the embodiments 1 to 7 wherein the separating step of the dialkylene glycol, and trialkylene product stream further produces dialkylene glycol stream, and trialkylene glycol stream comprising some amounts of heavy alkylene glycol. Embodiment 9 is the method of any of the embodiments 1 to 8 at least a portion of the dialkylene glycol product stream is recycled into the reaction unit. Embodiment 10 is the method of embodiment 2, wherein separating the first outlet stream further produces a water stream comprising water. The water stream is combined with the feed stream upstream of the reaction unit. Embodiment 11 is the method of any of embodiments 1 to 10, wherein the feed stream includes a water-to-alkylene oxide molar ratio in a range of 15 to 27. Embodiment 12 is the method of any of embodiments 1 to 11, wherein the monoalkylene glycol includes monoethylene glycol, trialkylene glycol includes triethylene glycol, the dialkylene glycol includes diethylene glycol, and the alkylene oxide includes ethylene oxide. Embodiment 13 is the method of any of embodiments 1 to 12, wherein the monoalkylene glycol, dialkylene glycol, and trialkylene glycol stream comprises 75 to 90 wt.% monoethylene glycol, 10 to 25 wt.% diethylene glycol, and 0.01 to 0.5 wt.% triethylene glycol. Embodiment 14 is the method of any of embodiments 1 to 13, wherein the reacting in the reaction unit is a non-catalytic step. Embodiment 15 is the method of any of embodiments 1 to 14, wherein the method is conducted as a continuous process. Embodiment 16 is the method of any of embodiments 1 to 15, wherein the reaction conditions in the reaction unit include a reaction temperature of 120 to 250 °C. Embodiment 17 is the method of any of embodiments 1 to 16, wherein the reaction conditions in the reaction unit include a residence time from 0.1 minute to 30 minutes, preferably 0.5 minute to 30 minutes, more preferably 1 minute to 30 minutes. Embodiment 18 is the method of any of embodiments 1 to 17, whereinmono-alkylene glycol, di-alkylene glycol, and tri-alkylene glycol are produced in the reaction unit from the alkylene oxide and the water in the feed stream.

[0057] All embodiments described above and herein can be combined in any manner unless expressly excluded.

[0058] Although 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 above disclosure, 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.

Claims

CLAIMSWhat is claimed is:

1. A method of producing an alkylene glycol, wherein the method comprises:(i) flowing a feed stream comprising an alkylene oxide and water to at least one inlet of a reaction unit;(ii) producing a first outlet stream comprising water, monoalkylene glycol, dialkylene glycol, trialkylene glycol or a combination thereof from the outlet of the reaction unit;(iii) passing the first outlet stream through a first separation unit to produce a second outlet stream comprising water and a third outlet stream comprising monoalkylene glycol, dialkylene glycol, trialkylene glycol or a combination thereof;(iv) recycling a portion of the third outlet stream to at least one inlet of the reaction unit; and(v) recycling the second outlet stream comprising water to at least one inlet of the reaction unit; wherein the feed stream comprises an alkylene oxide to water molar ratio in a range of 15 : 1 to 27 : 1 ; and wherein the recycled portion of the third outlet stream is in the range of from 0.1% to 35% of the third outlet stream.

2. The method according to claim 1, wherein the method further comprises: separating the third outlet stream in a second separation unit to produce a fourth outlet stream comprising monoalkylene glycol and a fifth outlet stream comprising dialkylene glycol and trialkylene glycol; and recycling a portion of the fourth outlet stream to at least one inlet of the reaction unit; wherein the recycled portion of the fourth outlet stream is in the range of from 0.1 % to 35% of the fourth outlet stream.

3. The method according to any of claims 1 to 2, wherein the method further comprises: recycling a portion of the fifth outlet stream to at least one inlet of the reaction unit; wherein the recycled portion of the fifth outlet stream is in the range of from 0.1% to 35% of the fifth outlet stream.

4. The method according to any of claims 1 to 3, wherein the method further comprises: separating the fifth outlet stream in a third separation unit to produce a sixth outlet stream comprising dialkylene glycol and a seventh outlet stream comprising trialkylene glycol; and recycling a portion of the sixth outlet stream to at least one inlet of the reaction unit; wherein the recycled portion of the sixth outlet stream is in the range of from 0.1% to 35% of the sixth outlet stream.

5. The method according to any of claims 1 to 4, wherein the method further comprises: mixing the recycled portions of the fourth outlet stream, the fifth outlet stream, the sixth outlet stream or a combination thereof with the recycled portion of the third outlet stream to produce an eighth outlet stream connected to said at least one inlet of the reaction unit; wherein the eighth outlet stream comprises a range of from 0.1% to 35% of the combined outlet streams from which the recycled portions of said outlet streams are taken.

6. The method according to any of claims 1 to 5, wherein the first outlet stream comprises water in a range of 75 wt.% to 90 wt.%, monoalkylene glycol in a range of 10 wt.% to 25 wt.%, dialkylene glycol in a range of 0.5 wt.% to 5 wt.%, and trialkylene glycol in a range of 0.01 wt.% to 0.5 wt.%.

7. The method according to any one of the previous claims, wherein the third outlet stream comprises monoalkylene glycol in a range of 80 wt.% to 95 wt.%, dialkyleneglycol in a range of 4.9 wt.% to 18 wt.%, and trialkylene glycol in a range of 0.1 wt.% to 2 wt.%.

8. The method according to any of claims 1 to 7, wherein the fourth outlet stream comprises monoalkylene glycol in a range of 99 wt.% to 100 wt.%.

9. The method according to any ofclaims 1 to 8, wherein the fifth outlet stream comprises dialkylene glycol of 90 wt.% to 98 wt.% and trialkylene glycol in a range of 2 wt.% to 10 wt.%.

10. The method according to any of claims 1 to 9, wherein the sixth outlet stream comprises dialkylene glycol in a range of 99 wt.% to 100 wt.%.

11. The method of any one of the previous claims, wherein reacting in the reaction unit is a non-catalytic step.

12. The method according to any of claims 1 to 11, wherein the combined flow rate of the recycled portions of the outlet streams is less than 25% of the flow rate of the feed stream.

13. The method according to any of claims 1 to 12, wherein the method is conducted as a continuous process.

14. The method according to any of claims 1 to 13, wherein reaction conditions in the reaction unit include a reaction temperature of 120 °C to 250 °C.

15. The method according to any of claims 1 to 14, wherein reaction conditions in the reaction unit include a residence time from 0.1 minute to 30 minutes, preferably 0.5 minute to 30 minutes, more preferably 1 minute to 30 minutes.

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