Improved reactor and method for reacting gaseous and liquid reactants - Patents.com

Abstract

The hybrid vertical bubble plug flow reactor is comprised of a bottom inlet and a top outlet with a vertical tubular member disposed between them, the bottom inlet having a separate gas reactant inlet and a separate liquid reactant inlet where the gas reactant is mixed with the liquid reactant, and the outlet having an extraction port that is sufficiently expanded to remove liquid product from the reactor and maintain a gas headspace inside the tubular member of the reactor. The hybrid vertical bubble plug flow reactor is useful for reacting gaseous and liquid reactants that exceed the stoichiometric requirements of the gaseous reactants and react at a gaseous reactant / liquid reactant molar ratio where the gaseous reactant forms bubbles and reacts in the presence of a catalyst where the reactants form reaction products.

Description

[Technical field]

[0001] The present invention relates to an improved method for reacting a gaseous reactant with a liquid reactant, particularly to the reaction of a gas and a liquid in the presence of a catalyst, such as the carbonylation of ethylene oxide with carbon monoxide, to form beta propiolactone (BPL). [Background technology]

[0002] Catalytic reactions of gaseous and liquid reactants have typically been carried out in stirred batch or continuous stirred reactors that maintain an overpressure of reactant gas and continuous injection of the gaseous reactant into the liquid. Batch reactors tend to use catalyst efficiently (i.e., have a high catalyst turnover number, or "TON"), but suffer from high capital costs for a given throughput and downtime between batches. In some instances, agitation for batch reactions can be achieved by bubbling the gaseous reactant with the liquid reactant (i.e., bubble reactors).

[0003] Continuously stirred reactors can produce product continuously, but suffer from inefficient use of catalyst and require continuous separation, recycling, and replenishment of the catalyst. Such operations can involve complex processes and technologies, such as separation membranes, which can result in dirty and inconsistent operation and products.

[0004] Plug flow reactors have not been commonly used for these reactions because they typically contain long coils of tubing to provide sufficient residence time and sufficient heat transfer area. These reactions typically require an overfeed of gaseous reactants beyond the solubility limits of the liquid / solvent, which often results in accumulation of gaseous reactants in the higher parts of the piping, resulting in variable liquid holdup / residence times in the reactor and unstable reaction conditions throughout the reactor.

[0005] It would therefore be desirable to provide a method for reacting a gaseous reactant and a liquid reactant that avoids one or more of the problems of the prior art, such as one of the problems discussed above. Summary of the Invention

[0006] Applicants have discovered that the hybrid vertical bubble plug flow reactor ("Reactor") herein can be used to react gaseous and liquid reactants, allowing for well-controlled reaction conditions, effective and efficient use of catalyst (e.g., high TON), while avoiding the problems associated with batch bubble reactors, continuous stirred tank reactors, and typical plug flow reactors.

[0007] A first aspect of the present invention is a method of reacting a gaseous reactant and a liquid reactant, comprising: (i) introducing the gaseous reactant and the liquid reactant separately at a bottom inlet into a hybrid vertical bubble plug flow reactor having a bottom inlet and a top outlet connected by a tubular member, where the gaseous reactant and the liquid reactant are mixed and introduced in a ratio that results in a molar ratio of gaseous reactant / liquid reactant that exceeds stoichiometric amounts and where the gaseous reactant forms bubbles in the liquid reactant; (ii) reacting the gaseous reactant and the liquid reactant in the presence of a catalyst to form a reaction product as they flow upward through the hybrid vertical bubble plug flow reactor, and removing the reaction product from the top outlet. Vertical in this specification means that the length of the tubular member is essentially parallel to the Earth's gravitational field vector (i.e., essentially parallel to the plumb line when determining vertical).

[0008] A second embodiment of the present invention is a reactor comprised of a bottom inlet and a top outlet with a vertical tubular member disposed between them, the bottom inlet having a separate gas reactant inlet and a separate liquid reactant inlet where the gas reactant is mixed with the liquid reactant, the outlet having an extraction port which is sufficiently enlarged to remove liquid product from the reactor and maintain a gas headspace inside said vertical tubular member of the reactor.

[0009] The process and reactor are particularly suited for reactions of liquid and gaseous reactants that do not react quickly and typically require a catalyst, such as the carbonylation of epoxides with carbon monoxide. Other reactions can be performed, for example, hydrogenation reactions (e.g., H 2 with unsaturated hydrocarbons) or the oxidation of hydrocarbons (for example, cyclohexane with oxygen, a "gas"). [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a diagram of a hybrid vertical tubular reactor of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] The descriptions and figures presented herein are intended to acquaint those skilled in the art with the invention, its principles, and its practical application. The specific embodiments of the present disclosure described are not intended to be exhaustive or to limit the scope of the present disclosure.

[0012] The method uses, but is not limited to, a hybrid vertical bubble plug flow reactor (reactor) 10 as shown in FIG. 1. The reactor 10 has a bottom inlet 20 and a top outlet 30 connected by a tubular member 40. The bottom inlet is comprised of separate gas reactant inlet 60 and liquid reactant inlet 70. The bottom inlet may further comprise other inlets for introducing drain 80 or other components. At the bottom inlet 20, the gas reactant is mixed with the liquid reactant which may be mixed with the solvent in a mixing region 90. The gas reactant inlet 60 may also comprise a sparger (not shown) to form a desired gas reactant bubble size within the liquid reactant and promote saturation of the liquid reactant and, if used, the solvent. The inlet may further comprise a screen mesh or the like 100 to retain any packing 45 in the vertical tubular member 40 or to further disperse or reduce gas reactant bubbles. The mesh can be anything, such as a product offered by Sealing Devices Inc., a pipe flange gasket with inlaid 316SS #20 mesh, used to encourage the bubbles to break up into smaller bubbles and retain the packing. It is understood that the bottom inlet can be configured in any manner that allows for injection and mixing of reactants at the bottom of the tubular member 40, such as a radial inlet at the bottom of the tubular member 40, or a vertical tube that runs from the top through the interior of the tubular member and out the bottom of the tubular member 40.

[0013] The outlet 30 is attached in any suitable manner of gas-liquid separation, such as those known in the art. In one embodiment, the outlet 30 is configured with an extraction tube 75 that extends far enough into the liquid product, solvent, and residual liquid reactants (reactor liquid 50) to allow extraction of the reactor liquid 50 and maintain a headspace 65 to provide an overpressure of the gas reactants. In the alternative, the extraction tube can be replaced with any other outlet, such as a radial extraction port, that also allows for the maintenance of a headspace. The extraction tube, port, or other outlet for the liquid product and residual solvent and unreacted liquid reactants can be associated with a separate gas outlet. The outlet 30 has an effluent outlet 95 for transporting the reactor liquid 50 for further processing, such as separation of the solvent and / or catalyst, further reaction, recovery, and a gas outlet 85 for maintaining a gas overpressure inside the reactor using suitable flow control devices, tanks, valves, and devices known in the art (not shown), which may be integrated or may be integral with the reactor.

[0014] Surprisingly, it has been discovered that the reactor can be used to react gaseous and liquid reactants. In particular, the method allows for more effective and efficient use of catalysts and achieving high TONs. Turnover number (TON) is used as commonly understood in the art and for continuous reactions, the amount of catalyst and product produced in a given time is the TON of the continuous reaction, given by (moles of product / hour) / (moles of catalyst / hour). TON indicates the effectiveness of the catalyst for continuous reactions with similar product output. In carrying out the method of the present invention, the liquid reactant is injected into the mixing zone 90 via the liquid reactant inlet 70 and the gaseous reactant is injected into the mixing zone 90 via the gaseous reactant inlet 60, where bubbles of the gaseous reactant are formed in the liquid reactant. The reactants can be cooled or heated when injected depending on the type of reaction being carried out. For example, for exothermic reactions such as the carbonylation described herein, it may be desirable to inject cooled reactants.

[0015] The tubular member 40 is oriented vertically, and while some deviation from the vertical may be tolerated, it is understood that essentially the reaction zone is straight without any bends or other obstructions that may trap the gaseous reactants. The tubular member 40 may have any cross-sectional shape, such as square, rectangular, square, hexagonal, pentagonal, elliptical, or circular, with circular being preferred. The materials of construction may be any that are compatible with the reactants and the conditions used to react the reactants, as may be readily determined by one of ordinary skill in the art. For example, where the reactants are epoxide and carbon monoxide, stainless steels (e.g., 302 or 316 stainless steel), inorganic glasses, organic plastics (e.g., engineering polymers), and ceramics may be used.

[0016] The length of the reactor 10 and the tubular member 40 can be any length and diameter useful to achieve the desired reaction conditions, such as residence time. Typically, the diameter of the tubular member can be from 2 mm, 3 mm, 5 mm or 1 cm to 200 cm, 100 cm, 50 cm, 20 cm or 10 cm. It is understood that the diameter of a non-cylindrical tubular member is taken as the largest dimension of the cross section of such a tubular member. Generally, the aspect ratio (length / diameter) is at least about 10, 15, or 20, to any commercially viable ratio, such as 1000, 500, 200, 100, 75, or 50.

[0017] In an embodiment, the reactor 10 may be comprised of multiple tubular members 40 in parallel with separate or shared flanges for the injection of reactants and removal of products. Such a parallel arrangement of tubular members 40 may be housed in a common vessel that may have, for example, a heating element or heat transfer fluid for commonly heating or cooling the tubular members 40. In another embodiment, the reactors 10 may be configured in series, for example, to inject additional or different reactants or catalysts or to react products from one reactor in a subsequent reactor to form a different product. Similarly, a combination of parallel and series reactors may be configured to allow for the continuous formation of different products and to allow for tunable mixing of such products.

[0018] In another embodiment, the tubular member 40 may further be configured with one or more radial inlets along its length for injecting additional reactants or other components (e.g., solvents, stabilizers, surfactants, etc.). It is understood that such other components, just like solvents, may also be injected at the bottom inlet. For example, a radial inlet may be used to inject the same gas or liquid reactant inserted at the bottom inlet 20 along the length of the tubular member 40. If a gas reactant is injected through a radial inlet, it may include a nebulizer, as described herein. In another embodiment, different reactants may be inserted through one or more radial inlets to form different desired end products. As previously described, the reactants or any additional components may be heated or cooled depending on the desired reaction or reaction conditions.

[0019] The injection ratio of gas reactant / liquid reactant is such that it is a molar excess stoichiometric amount of gas reactant to the desired reaction. By way of example, the molar ratio (or equivalence ratio) of gas reactant / liquid reactant is from 1, 1.1, 1.2, 1.4, or 1.5 to about 20, 10, 7, 5, 4, or 3 or more. Without being limiting in any way, it is believed that the excess gas reactant allows the gas reactant to maintain saturation of the liquid reactant throughout the residence time inside the reactor, to avoid starving the reactor of gas reactants. Similarly, it is believed that an excess amount of gas reactant can cause the liquid reactant, product, or solvent to evaporate into bubbles formed inside the liquid reactant, thus inhibiting the catalytic reaction, without being limiting in any way.

[0020] Desirably, the bubbles formed in the liquid reactant are of a size that increases saturation within the liquid reactant and distributes uniformly throughout the reactor. In an embodiment, an atomizer can be used when injecting the gas reactant. The atomizer can be any of those commonly used in the chemical or biochemical industries. For example, the atomizer can be a porous sintered ceramic frit or a porous metal frit, such as those available from Mott Corp., Farmington, Connecticut. The pore size of the porous sintered frit atomizer can be any useful, such as those having a pore size of 0.5 micrometers, 1 micrometer, 2 micrometers to 100 micrometers, 50 micrometers, 20 micrometers, or 15 micrometers. Examples of other gas atomizers that may be suitable include perforated plates, needles, spiders, or combinations of various sizes of openings thereof, depending on the size of the bubbles desired.

[0021] In another embodiment, the desired bubble size or reactant distribution may be promoted in the reactor using packing 45. Packing 45 may be any useful in disrupting the formation of larger bubbles and breaking up larger bubbles, such as those known in the art and for distributing reactants. For example, packing 45 may be porous packing, such as those commonly used in plug flow reactors to ensure good radial mixing and promote plug flow through the reactor. Packing 45 may be beads of any useful shape, monolithic or segmented in-line static mixing or screw structures, distribution plates or sieves.

[0022] In further embodiments, the desired bubble size may be facilitated by the use of surfactants, including but not limited to separately added ionic (cationic, anionic, and amphoteric surfactants) or non-ionic surfactants. The surfactants may be mixed into the liquid reactants at the time of injection or may be separately inserted into the inlet 20. In embodiments, the surfactants may be generated in situ as a by-product. For example, glycol-based oligomers may be generated when epoxides or lactones are carbonylated with carbon monoxide.

[0023] When the packing 45 is a bead, the bead may be any useful shape, such as a sphere, spheroid, cone, cylinder, flat perforated sheet of any cross-sectional shape, tube, cube, or fiber. In embodiments, the beads may be of a single size (same volume or equivalent sphere diameter if not spherical) or may be of a range of sizes, including bimodal, trimodal, or continuous size distributions. Generally, the beads range in size from 1 mm to about 25 mm.

[0024] The bead size can be any useful size that promotes plug flow and bubble breakup, as discussed above. Packing 45 typically creates a void fraction of about 20% to 99% within tubular member 40. Typically, the void fraction is from 25% or 30% to 80%, 90%, or 95%.

[0025] Packing 45 can be made of any suitable material useful for handling the reactants and reaction conditions used. Suitable bead materials can include, for example, ceramics (e.g., crystalline oxides, nitrides, carbides, and amorphous silicates, aluminates, borates, and combinations thereof), plastics (e.g., polyolefins, fluoropolymers, polycarbonates, polyesters, and combinations thereof), metals (e.g., transition metals and their alloys), or combinations of any of the foregoing. Particular examples include porous borosilicate glass, silica glass, soda-lime glass, alumina, stainless steel, nickel alloys, or combinations thereof. In a particular embodiment, packing 45 is a perforated 316 stainless steel tab available under the trade name PRO-PAK (Cannon Instrument Co.,). In an embodiment, the method uses both the atomizer and packing. In a further embodiment, packing 45 can be catalytic, as described below.

[0026] In the method, it is desirable for the gas bubbles to flow through the reactor 10 at the same or higher speed (velocity) than the liquid reactants. Without imposing any limitations, it is believed that this promotes saturation of the gas reactants with the liquid reactants, creates agitation throughout the reactor, and increases reaction efficiency and effectiveness (e.g., higher TON and selectivity). Typically, the gas bubbles have a velocity through the reactor 10 at least about 1.1 or 1.5 to 10, 5, or 4 times faster than the liquid reactants and any solvent, if used. In other words, the gas bubbles have a shorter residence time than the liquid reactants at a similar rate to that given for velocity (e.g., 0.9 or 0.67 to 0.1, 0.2, or 0.25 of the residence time).

[0027] In embodiments, a gas headspace 65 is maintained inside the tubular member 40, for example, to facilitate saturation of the gaseous reactants in the liquid reactants and solvent, if used. The headspace 65 can be maintained at any pressure useful for the reaction conditions used to react the particular reactants, as described above. By way of illustration, if the liquid reactant is an epoxide (e.g., ethylene oxide and / or propylene oxide) or beta lactone (beta butyrolactone and / or beta propiolactone) and the gaseous reactant is carbon monoxide, the pressure may range from greater than 1, 2, 3, 4, or 5 bar to about 100, 50, 20, or 15 bar. In embodiments, the headspace 65 can also be used to facilitate maintenance of the liquid state of the liquid reactants. For example, if the reactants are normally gaseous at ambient conditions (essentially ambient conditions of 20 to 25° C. and about 1 atm), the liquid reactants can be partially maintained by having sufficient overpressure as described above.

[0028] The process may be carried out at any useful temperature for the particular reactants and products desired. By way of example, for carbonylation of an epoxide or lactone, the temperature may be from about 50° C., 60° C., 70° C. to 200° C., 150° C., 125° C., or 100° C. Heating or cooling of the reactor may be carried out by any suitable method or apparatus as known in the art. For example, reactor 10 may include a temperature control jacket, not shown in the photograph. Typically, this may include a heat exchange conduit, such as a channel in the wall of tubular member 40, that allows a cooling or heating liquid to pass through the reactor to transfer heat to and from the reactor to control the temperature of the reaction or heating / cooling tubes immersed inside tubular member 40, or it may be any known heating or cooling method, such as a heating tape or one or more tubes wrapped around tubular member 40, a channel within the wall of tubular member 40, or a tube within tubular member 40 (i.e., the reactants contact the walls of the tubes inside the reactor), or any combination thereof.

[0029] The process can utilize any ratio of introduction of reactants to achieve a suitable residence time inside the reactor 10. In general, the residence time inside the reactor 10 can be from 2, 5 or 10 minutes to 24 hours, 10 hours, 5 hours, 3 hours, 2 hours or 1 hour depending on the reactants such as epoxides, lactones, or combinations thereof with carbon monoxide. In an embodiment, surprisingly, the reactor 10 can be used to carbonylate epoxides to lactones, which are then further reacted to form anhydrides. This is surprising because there is a continuous feed of epoxide into the reactor and the catalyst is highly selective in forming lactones in the presence of epoxides. The process can also recycle the effluent, for example to achieve a mixture of desired products, particularly recycled CO, when it may be particularly desirable to perform the carbonylation reactions described herein.

[0030] In the method, the reaction is carried out in the presence of a catalyst. The catalyst can be a homogeneous catalyst, a heterogeneous catalyst, or a combination thereof. In an embodiment, the catalyst is present in the liquid reactant as it is injected into the reactor 10 via the liquid reactant inlet 70. For example, the catalyst is a homogeneous catalyst dissolved in the liquid reactant, or a heterogeneous catalyst present as particles in the liquid reactant (slurry) prior to insertion into the reactor 10. In another embodiment, the catalyst is comprised of a heterogeneous catalyst fixed to a support, which may be used, in part or in whole, as packing 45. By way of illustration, the heterogeneous catalyst may be a supported catalyst useful for the carbonylation of epoxides or lactones, as described in co-pending application PCT / US2020 / 044013, which is incorporated herein by reference. The support may be a porous ceramic, such as the packing beads described above, and in an embodiment may be a zeolite, silica, titania, silver (e.g., silver in a clay-bound material), as described in paragraph 36 of said co-pending application, which is incorporated herein by reference. Other exemplary catalysts for the carbonylation of epoxides or lactones are described in US Pat. Nos. 6,852,865 and 9,327,280 and US Pat. Appl. Nos. 2005 / 0014977 and 2007 / 0213524, each of which is incorporated herein by reference.

[0031] The amount of catalyst can be any useful amount and can depend on the particular reactants and products desired. Generally, the amount of catalyst present in the reactor is about 0.001% to 20% by weight of the amount of reactants present in reactor 10. Illustratively, when the catalyst is a homogeneous catalyst dissolved or mixed in the liquid reactants, the amount of catalyst is about 0.001%, 0.01%, 0.05% to about 20%, 10% or 5% by weight of the liquid reactants and catalyst. As further illustration, when carbonylating an epoxide or lactone with carbon monoxide, the amount of homogeneous catalyst is fed to the reactor with the epoxide or lactone at a liquid reactant / catalyst molar ratio of 50, 100 to 50,000, 25,000, 10,000, 5,000 or 2,500.

[0032] The liquid reactant may be present, mixed, or entrained in a solvent. Any useful solvent may be used. The solvent may be used to increase the presence of, for example, a gaseous reactant in the liquid reactant. By way of illustration, if the liquid reactant is an epoxide, the solvent may be an organic solvent such as an aliphatic hydrocarbon, an aromatic hydrocarbon, a halogenated solvent, an ether, an ester, a ketone, a nitrile, an amide, a carbonate, an alcohol, an amine, a sulfone, a mixture thereof, or a combination thereof. Exemplary solvents may include diethyl ether, methyl-t-butyl ether, tetrahydrofuran, 1,4-dioxane, glyme, diglyme, triglyme, higher glymes, or a mixture thereof. The amount of solvent may be any amount useful for carrying out the method and may vary over a wide range. For example, the amount of solvent to liquid reactant by weight (solvent / liquid reactant) may vary from 1, 10, or 20 to 99, 90, or 80.

[0033] The gaseous reactant may also be present in, mixed with, or entrained in another gas. For example, the gaseous reactant may be mixed with another gas, such as an inert gas or nitrogen. In certain embodiments, the reactant gas is carbon monoxide mixed with hydrogen, such as commercially available synthesis gas, as described in U.S. Pat. No. 10,597,294, incorporated herein by reference, and can be used in the carbonylation of epoxides, lactones, or combinations thereof.

[0034] In certain embodiments of the method, the liquid reactants are epoxides or lactones and carbon monoxide to form the corresponding carbonylated lactone, anhydride products, which refers to substituted or unsubstituted oxiranes. Substituted oxiranes include mono-substituted oxiranes, di-substituted oxiranes, tri-substituted oxiranes, and tetra-substituted oxiranes. Such epoxides may be further optionally substituted. In some embodiments, the epoxides are composed of one oxirane moiety. In some embodiments, the epoxides are composed of two or more oxirane moieties. The lactones may be any lactones, such as those produced upon carbonylating the aforementioned epoxides. Examples of such epoxides and lactones include ethylene oxide, propylene oxide, and their corresponding lactone carbonylation products, beta propiolactone and beta butyrolactone. Examples of such lactones include beta propiolactone, beta butyrolactone, and their corresponding carbonylation products, succinic anhydride and methylsuccinic anhydride. Further examples of epoxides and lactones can be found in Table A (between paragraphs 65 and 66) of PCT Publication WO2020 / 033267, which is incorporated herein by reference.

[0035] <Example> (Example 1) A method for reacting a gas reactant with a liquid reactant, comprising the steps of: (i) introducing the gaseous reactants and the liquid reactants separately at a bottom inlet into a hybrid vertical bubble plug flow reactor having the bottom inlet and a top outlet connected by a tubular member, wherein the gaseous reactants and the liquid reactants are mixed and introduced in a ratio that results in a gaseous reactant / liquid reactant molar ratio that exceeds stoichiometric amounts and in which the gaseous reactant forms bubbles in the liquid reactant; (ii) reacting the gaseous reactant and the liquid reactant in the presence of a catalyst to form a reaction product as they flow upwardly through the hybrid vertical bubble plug flow reactor; and (iii) removing said reaction products from said top outlet. Example 2: The method of Example 1, wherein a gas headspace is maintained in the reactor. (Example 3) The method of any one of the preceding examples, wherein the gas reactant / liquid reactant molar ratio is from 1.2 to about 20. (Example 4) The method according to Example 3, wherein the molar ratio is from 1.5 to about 5. (Example 5) The method of any one of the preceding examples, wherein the tubular member of the reactor has packing therein. (Example 6) The method of any one of the preceding examples, wherein the gaseous reactant is introduced through a nebulizer. (Example 7) The method of any one of the preceding examples, wherein the gas bubbles pass through the reactor at a velocity and the liquid reactant passes through the reactor at a velocity, the velocity of the gas bubbles being the same as or greater than the velocity of the liquid reactant. (Example 8) The method of any one of the preceding examples, wherein the liquid reactant is dissolved in a solvent. Example 9. The method of any one of the preceding examples, wherein the liquid reactant is a gas at ambient conditions and the reactor is maintained at a pressure and temperature at which the liquid reactant is maintained as a liquid. (Example 10) The method of any one of the preceding examples, wherein the gaseous reactant is carbon monoxide and the liquid reactant is an epoxide. (Example 11) The method of Example 10, wherein the epoxide is ethylene oxide, propylene oxide, or a combination thereof. (Example 12) The method according to any of the preceding examples, wherein the liquid reactant is beta-lactone. (Example 13) The method of Example 12, wherein the beta-lactone is beta-butyrolactone, beta-propiolactone, or a combination thereof. (Example 14) The method of any one of the preceding examples, wherein the catalyst comprises a homogeneous catalyst that is introduced with the reactants and flows through the reactor with the reactants and the reaction products. Example 15. The method of Example 14, wherein a homogeneous catalyst is mixed with the liquid reactants and introduced into the reactor together with the liquid reactants. (Example 16) The method of any one of the preceding examples, wherein the catalyst comprises a heterogeneous catalyst fixed to a support dispersed within the interior of the tubular member of the reactor. (Example 17) The method according to Example 16, wherein the rigid support is composed of the packing. (Example 18) The method of any one of the preceding examples, wherein the pressure is maintained at about 1 bar to about 100 bar. (Example 19) The method of Example 18, wherein the pressure is maintained at about 2 bar to 50 bar. Example 20. The method of any one of the preceding examples, wherein multiple reactors are used in series, parallel, or a combination thereof. Example 21 The method of Example 20, wherein at least two reactors are present in series. Example 22. The method of Example 21, wherein at least two reactors are in series and the product of one reactor becomes the liquid reactant of a subsequent reactor. (Example 23) The method of any one of the preceding examples, wherein the product is separated from the gaseous reactants, catalyst, and solvent, if present. (Example 24) The method of any one of the preceding examples, wherein the reactor has a length / diameter aspect ratio of at least about 10. (Example 25) The method described in Example 24, wherein the aspect ratio is at least 20 to 1000. (Example 26) The method described in Example 25, wherein the diameter is from about 1 cm to about 200 cm. (Example 27) The method according to any one of the preceding examples, wherein the temperature is about 50°C to 200°C. (Example 28) The method of any one of the preceding examples, wherein a surfactant is present in the reactor. (Example 29) The method of Example 28, wherein the surfactant is added separately. (Example 30) The method of Example 28, wherein the surfactant is generated in situ during the reaction as a by-product. (Example 31) The method of any one of the preceding examples, wherein the bubbles are sized to maintain saturation of the gaseous reactant in the liquid reactant and any solvent, if present. (Example 32) The method of any one of the preceding examples, further comprising injecting the gas reactant, the liquid reactant, other reagents, or a combination thereof along the length of the cylindrical member of the hybrid vertical bubble plug flow reactor. (Example 33) The method of any one of the preceding examples, wherein the liquid reactant is comprised of an epoxide, the gaseous reactant is comprised of carbon monoxide, and the reaction product is comprised of anhydride, and the method is carried out in a hybrid vertical bubble plug flow reactor. (Example 34) A reaction product produced by the method according to any one of the preceding examples. (Example 35) The reaction product of Example 34, wherein the reaction product comprises a lactone or anhydride compound. (Example 36) The reaction product of Example 35, wherein the reaction product comprises beta-butyrolactone, beta-propiolactone, methylsuccinic anhydride, succinic anhydride, or a combination thereof. (Example 37) A reactor consisting of a bottom inlet and a top outlet with a vertical tubular member disposed between them, the bottom inlet having a separate gas reactant inlet and a separate liquid reactant inlet where the gas reactant is mixed with the liquid reactant, and an extraction port in the vertical tubular member, the extraction port being sufficiently enlarged to remove the liquid product from the reactor and maintain a gas headspace within the vertical tubular member of the reactor. (Example 38) The reactor of Example 37, wherein the gas reactant inlet comprises a sparger. (Example 39) A reactor described in either Example 37 or 38, wherein the tubular member has packing therein. (Example 40) A reactor described in any one of Examples 37 to 39, wherein the tubular member has a length and a diameter, and the length / diameter ratio is at least 10. (Example 41) The reactor of any one of Examples 37 to 40, further comprising a radial inlet along the length of the tubular member. (Example 42) The reactor of Example 41, wherein the radial inlet is configured to deliver a gaseous reactant. (Example 43) The reactor of Example 42, wherein the gas reactant is the same as the gas reactant mixed with the liquid reactant at the bottom inlet. (Example 44) The reactor of any one of Examples 37 to 43, wherein the temperature is controlled by a heat exchange element. (Example 45) A reactor as described in Example 44, wherein the heat exchange element is composed of a tube or channel through which a heat exchange liquid passes. (Example 46) A reactor as described in Example 45, wherein the heat exchange element is comprised of one or more of a tube inside the tubular member, a channel in the wall of the tubular member, or a tube wrapped around the tubular member.

[0036] Illustrative Embodiments The following examples are provided to illustrate the process and reactor without limiting the scope of the invention. All parts and percentages are by weight unless otherwise stated. Table 1 shows the ingredients used in the examples and comparative examples. EXAMPLES

[0037] The laboratory scale hybrid bubble plug flow reactor 10 is constructed from a tubular member 40 fabricated using 316 stainless steel and 2 feet of 1 inch diameter pipe with flanges at the top outlet 20 and bottom outlet 30 in a similar manner as shown in FIG. 1 except that the gas and liquid reactant inlets and drains are made using two radial port bleed flanges and a bottom drain valve 80. The tubular member 40 is packed with PROPAK packing leaving about 1 inch headspace 65. The reactor has a 316 stainless steel strainer 100 (pipe flange gasket with inlaid 316SS #20 mesh available from Sealing Devices Inc) on top of the bottom bleeder flange. A ¼ inch 316 stainless steel dip tube 75 is used to extract the effluent as described herein.

[0038] The reactor was preheated and maintained at the temperature shown in Table 1. Ethylene oxide in tetrahydrofuran (THF) was injected into the reactor and CO was injected into the reactor separately as shown in Table 1 for each example. Each example was run for several hours, ensuring that the reaction occurred for multiple residence times. The catalyst used was the same in each example. The catalyst was essentially the same as that described in US Pub. No. 2019-0030520. The effluent composition and concentrations are shown in Table 2. Reactor performance metrics are shown in Table 3. All concentrations are by weight unless otherwise indicated. No buildup of bubbles was observed in any of the examples.

[0039] Example 1 shows that anhydrous compounds may be made in one reactor. Other examples show the wide range of operating conditions that can be used when reacting liquid and gaseous reactants.

[0040] Example 17 was made using the same reactor as Examples 1-16 and run under the conditions shown in Table 4. Comparative Example 1 was made in a continuous stirred reactor under conditions having substantially the same residence time and reactor outlet beta propiolactone (bPL) concentration as Example 17, also shown in Table 4. From this, it is readily apparent that the reactor of the present invention has a much higher TON for a given residence time and bPL yield than a continuously stirred reactor operating under similar conditions and product yield. Surprisingly, the bPL yield is comparable while using significantly less catalyst per mole of product output and essentially the same residence time, which is reflected in a significant increase in TON on a unit time basis. [Table 1-1] [Table 1-2] [Table 2] [Table 3] [Table 4]

Claims

1. 1. A method for reacting a gaseous reactant with a liquid reactant, comprising: (i) introducing said gaseous reactants and said liquid reactants separately at a bottom inlet into a hybrid vertical bubble plug flow reactor having said bottom inlet and top outlet connected by a tubular member, said gaseous reactants and said liquid reactants being mixed and introduced in a ratio that results in a molar ratio of gas reactant / liquid reactant that exceeds stoichiometric amounts and in which said gaseous reactant forms bubbles in said liquid reactant, said liquid reactant being a gas at ambient conditions, said reactor being maintained at a pressure and temperature at which said liquid reactant is maintained as a liquid, said bubbles passing through said reactor at a velocity and said liquid reactant passing through said reactor at a velocity, said velocity of said bubbles being equal to or greater than said velocity of said liquid reactant; (ii) reacting the gaseous reactant and the liquid reactant in the presence of a catalyst to form a reaction product as they flow upward through the hybrid vertical bubble plug flow reactor; and (iii) removing said reaction products from said top outlet.

2. The method of claim 1 , wherein a gas headspace is maintained in the reactor.

3. 2. The method of claim 1 , wherein the gas reactant / liquid reactant molar ratio is from 1.2 to 20.

4. 10. The method of claim 1, wherein the tubular member of the reactor has packing therein and the gaseous reactants are introduced through an atomizer.

5. The method of claim 1 , wherein the liquid reactant is dissolved in a solvent.

6. The method of claim 1, wherein the velocity of the bubbles is at least 1.1 to 10 times faster than the velocity of the liquid, and the bubbles are sized to maintain saturation of the gas reactant in the liquid reactant and any solvent, if present.

7. 2. The method of claim 1, wherein the gas reactant is carbon monoxide and the liquid reactant is an epoxide or a beta-lactone.

8. 8. The process of any one of claims 1 to 7, wherein the catalyst consists of a homogeneous catalyst that is introduced with the reactants and flows through the reactor with the reactants and the reaction products.

9. The method according to any one of claims 1 to 7, wherein the catalyst comprises a heterogeneous catalyst fixed to a support dispersed inside the tubular member of the reactor.

10. 2. The method of claim 1, wherein the pressure is maintained at about 1 bar to about 100 bar and the temperature is at about 50° C. to 200° C.

11. 10. The method of claim 1, wherein multiple reactors are used in series, parallel, or a combination thereof.

12. 12. The method of claim 11, wherein there are at least two reactors in series, and the product of one reactor becomes the liquid reactant of a subsequent reactor.

13. The process of claim 1 , wherein a surfactant is present in the reactor.

14. 10. The method of claim 1, further comprising injecting the gas reactant, the liquid reactant, other reagents, or a combination thereof along the length of the cylindrical member of the hybrid vertical bubble plug flow reactor.

15. 2. The method of claim 1, wherein the liquid reactant is comprised of an epoxide, the gaseous reactant is comprised of carbon monoxide, and the reaction product is comprised of an anhydride, and the method is carried out in a hybrid vertical bubble plug flow reactor.

Images