Patent Application
20190023672
The invention generally concerns methods for the direct of epoxidation of propylene with oxygen and optionally hydrogen. In a particular aspect, the methods allow for the ability to safely provide oxygen, propylene, and optionally hydrogen to a reactor system and produce propylene oxide. The reaction conditions, which include (1) at least 50 vol. % propene, 1 to 15 vol. % O2, and optionally 1 to 15 vol. % H2 and (2) a temperature of 150° C. to 300° C. and a pressure of 3 bar to 20 bar, remain outside of the explosive regime due to the reactor configuration.
Propylene oxide (PO) is an important chemical intermediate for the production of numerous commercial materials. For example, PO can be used to make propylene glycols and polyether polyols (e.g., polyglycol ethers, propylene glycol ethers, etc.). These chemical compounds can be used many commercial applications such as rigid foam insulations, flexible foam applications, flame retardants, starches, synthetic lubricants, oil field drilling chemicals, textile surfactants, food product additives, cosmetic applications, and the like.
One conventional method to make PO includes the reaction of propylene with chlorohydrin as shown in reaction Scheme I.
This method suffers from environmental liabilities and has high capital costs. These plants are often integrated with chloro-alkali plants to make the chlorine and caustic soda, which consume a large amount of power. Further, extensive effluent treatment may be needed to handle the large dilute calcium chloride brine waste stream.
Another conventional method to make PO includes a hydroperoxide method using, for example, cumene hydroperoxide as shown in reaction Scheme (II) or analogues thereof.
This reaction suffers in that the co-product a benzyl alcohol (alpha, alpha-dimethylbenzyl alcohol) must be isolated, and through a series of chemical steps converted to cumene, which is then oxidized by oxygen to cumene hydroperoxide.
Yet another conventional method to make PO includes the oxidation of propylene with hydrogen peroxide as shown in reaction Scheme (III). Commercially, propylene oxide can be made using anthraquinone to generate hydrogen peroxide. An alkylanthraquinone precursor dissolved in a mixture of organic solvents followed by liquid-liquid extraction to recover H2O2. The AO process is a multistep method that requires significant energy input and generates waste, which has a negative effect on its sustainability and production costs. The hydrogen peroxide is reacted with the propylene to make PO and water (HPPO process). This method suffers in that it requires significant energy input and generates waste, which has a negative effect on its sustainability and production costs
To overcome the limitations of the aforementioned conventional processes, direct epoxidation of propylene as shown in reaction Scheme (IV) using a wide variety of heterogeneous and homogeneous catalysts has been investigated. These methods suffer in that undesirable by-products (side products not shown in Scheme IV) or high amounts of water are produced, both of which result in low yields of propylene oxide.
Still further, the above direct epoxidation of propylene reaction is typically carried out with dilute gas mixtures in which each of the reactants (propylene, oxygen, and hydrogen) is present at concentrations of 10 vol. % or lower and operated at relatively low pressures (typically around 1 bar) and/or temperatures (typically less than 150° C.). These conditions are used to avoid running the reaction within an explosive regime of the reactants. While this can be safely performed, a downside is decreased efficiency of the reaction.
There has been at least one attempt to run the direct epoxidation of propene reaction in the explosive regime (See, Nijhuis et al., “The Direct Epoxidation of Propene in the Explosive Regime in a Microreactor—A Study into the Reaction Kinetics”, Ind. Eng. Chem. Res., 2010, 49, 10479-85). However, the reactor used in Nijhuis et al. was a microreactor, which prevents scalability to commercial production of propylene oxide.
A solution to the problems of direct epoxidation of propylene has been discovered. The solution is premised on the ability to safely provide oxygen, propylene, and optionally hydrogen to a reactor system and produce propylene oxide. The reaction conditions, which include (1) at least 50 vol. % propene, 1 to 15 vol. % O2, and optionally 1 to 15 vol. % H2 and (2) a temperature of 150° C. to 300° C. and a pressure of 3 bar to 20 bar, remain outside of the explosive regime due to the reactor configuration. In particular, the reaction can be safely performed under such reaction conditions by introducing propene through a first reactant feed stream and manipulating the introduction of oxygen gas (O2) and optionally hydrogen gas (H2) through separate feed streams over the length of the catalytic bed or the length of the reaction zone. By way of example, the O2 feed stream and optionally the H2 feed stream can be gradually (either incrementally, intermittently or both) introduced over the length of the catalytic bed or reaction zone such that an explosive concentration of propene, O2, and H2 (if present) is not exceeded at any point throughout the length of the reaction zone. Without wishing to be bound by theory, it is believed that these reaction parameters and conditions allow for the use of an overall explosive regime within a given reactor, but reduces the possibility of exceeding an explosive concentration of the reactants at any point within the reaction zone. This has the advantage of being able to safely operate the direct epoxidation of propene reaction under conditions that can maximize the efficiency of the reaction (e.g., reduced water production, increased propylene oxide yield, decreased production of by-products, and increased catalyst stability). Notably, any type of epoxidation catalyst can be used with the process of the present invention, as the improvements offered by the present invention focus on the reaction conditions rather than a specific catalyst.
In one aspect of the present invention, a method for direct epoxidation of propylene is described. The method can include reacting, in a reaction zone of a reactor (e.g., a continuous flow reactor selected from a fixed-bed reactor, a fluidized reactor, a plate reactor, a membrane reactor or a moving bed reactor), propene, oxygen gas (O2), and hydrogen gas (H2) in the presence of a catalytic bed that includes a propene epoxidation catalyst to produce a product stream that includes propylene oxide and, in some instances, water. At least 50 vol. % propene, 1 to 15 vol. % O2, and 1 to 15 vol. % H2 can be maintained in the reaction zone during the reaction by (i) introducing the propene through a first reactant feed stream and (ii) gradually introducing the O2 or the H2, or both, over the length of the catalytic bed or the length of the reaction zone through a separate reactant feed stream(s). The reaction can be performed at a temperature of 150° C. to 300° C., preferably 200° C. to 275° C., and a pressure of 3 bar to 20 bar, preferably 5 to 15 bar. In a particular aspect, 82 vol. % to 95 vol. % of propene, preferably 88 vol. % to 92 vol. % of propene, 3 vol. % to 8 vol. % O2, preferably 4 vol. % to 6 vol. % O2, and 2 vol. % to 10 vol. % H2, preferably, 4 vol. % to 6 vol. % H2, can be maintained in the reaction zone during the reaction. While the overall vol. % of propene, O2, and/or H2 in the reaction zone can be within the explosive regime/range, an explosive concentration of these reactants is not exceeded at any point throughout the length of the reaction zone due to the gradual introduction of O2 and/or H2 into the reaction zone. Gradual introduction can be performed through incremental introduction or intermittent introduction, or both, over the length of the catalytic bed or the length of the reaction zone. In some instances, H2 is introduced gradually over the length of the catalytic bed or the length of the reaction zone in a second reactant feed stream through a membrane that is positioned proximate to the catalytic bed and/or O2 is introduced over the length of the catalytic bed or the length of the reaction zone in a third feed stream through a second membrane that is positioned proximate to the catalytic bed. In one instances, O2 or H2 is introduced with the propene in the first reactant feed stream. The first reactant feed stream can be introduced through an inlet positioned upstream from the catalytic bed. In some instances, the separate reactant feed stream that gradually introduces O2 or H2, or both, over the length of the catalytic bed or the length of the reaction zone is introduced through a second inlet that is positioned downstream from the first inlet. The H2 can be gradually introduced over the length of the catalytic bed or the length of the reaction zone through a second inlet that can be positioned downstream from the first inlet and the H2 is introduced over the length of the catalytic bed or the length of the reaction zone through a third inlet that can be positioned downstream from the first inlet. In a particular instance the gradual introduction of O2 or H2, or both can be accomplished with a reactor having alternating plates. This can be accomplished, for instance, by using a reactor that includes alternating plates of an oxygen feed plate, an epoxidation catalyst plate, a hydrogen feed plate, a second epoxidation catalyst plate, a second oxygen feed plate, a third epoxidation catalyst plate, a second hydrogen feed plate, etc. The first reactant feed stream can include an inert gas (e.g., helium, nitrogen, argon, water vapor, carbon dioxide or any combination thereof) that is not involved/not consumed with the epoxidation of propene reaction. The reaction conditions can include a weight hourly space velocity (WHSV) of between 1 and 200 h−1. The propylene epoxidation catalyst can be in particulate or powdered form. In other instances, the propylene epoxidation catalyst can be formed to have a selected shape (e.g., extrudated catalysts, spherically catalysts, pellets, or structured catalysts such as monoliths, foams, etc.). The catalyst can include titanium, gold, palladium, platinum, silver or any combination or alloy thereof. Still further, the propylene epoxidation catalyst can be supported by a support material (e.g., metal oxide supports such as silica or titania, zeolite supports such as TS-1, Ti-Beta, etc.). In general, any known propylene epoxidation catalyst can be used in the context of the methods of the present invention.
In another embodiment of the present invention there is disclosed a method for direct epoxidation of propene without using hydrogen gas (H2) as a reactant. The method can include reacting, in a reaction zone of a reactor, propene and oxygen gas (O2) in the presence of a catalytic bed that includes a propene epoxidation catalyst to produce a product stream comprising propylene oxide, where (1) at least 50 vol. % propene and 1 to 15 vol. % O2 is maintained in the reaction zone during the reaction by (i) introducing the propene through a first reactant feed stream and (ii) gradually introducing the O2 over the length of the catalytic bed or the length of the reaction zone through a separate reactant feed stream; (2) a temperature of 150° C. to 300° C. and a pressure of 3 bar to 20 bar is maintained in the reaction zone during the reaction; and (3) the direct epoxidation of propene reaction is performed in the absence of H2 gas. Other than the absence of hydrogen gas in the reaction, the reaction can occur under the same parameters and processing conditions as those discussed above and throughout the present invention. Still further, this reaction can be performed in the complete absence of H2 or with non-reactive amounts of H2, such that H2 is not present in an amount to effect the overall production of propylene oxide.
In the context of the present invention 43 embodiments are described. The first embodiment describes a method for direct epoxidation of propene. The method can include reacting, in a reaction zone of a reactor, propene, oxygen gas (O2), and hydrogen gas (H2) in the presence of a catalytic bed that includes a propene epoxidation catalyst to produce a product stream comprising propylene oxide, where at least 50 vol. % propene, 1 to 15 vol. % O2, and 1 to 15 vol. % H2 is maintained in the reaction zone during the reaction by (i) introducing the propene through a first reactant feed stream and (ii) gradually introducing the O2 or the H2, or both, over the length of the catalytic bed or the length of the reaction zone through a separate reactant feed stream(s), and a temperature of 150° C. to 300° C. and a pressure of 3 bar to 20 bar is maintained in the reaction zone during the reaction. Embodiment 2 is the method of embodiment 1, wherein 82 vol. % to 95 vol. % of propene, 3 vol. % to 8 vol. % O2, and 2 vol. % to 10 vol. % H2 is maintained in the reaction zone during the reaction. Embodiment 3 is the method of embodiment 2, wherein 88 vol. % to 92 vol. % of propene, 4 vol. % to 6 vol. % O2, and 4 vol. % to 6 vol. % H2 is maintained in the reaction zone during the reaction. Embodiment 4 is the method of any one of embodiments 1 to 3, wherein the vol. % of propene and O2 or H2, or both, in the reaction zone has an explosive regime, and wherein the gradual introduction of O2 or H2, or both, in the reaction zone is such that an explosive concentration of propene and O2 or H2, or both, is not exceeded at any point throughout the length of the reaction zone. Embodiment 5 is the method of any one of embodiments 1 to 4, wherein a temperature of 200° C. to 275° C. and a pressure of 5 bar to 15 bar is maintained in the reaction zone during the reaction. Embodiment 6 is the method of any one of embodiments 1 to 5, wherein O2 or H2, or both, are introduced incrementally over the length of the catalytic bed or the length of the reaction zone. Embodiment 7 is the method of any one of embodiments 1 to 5, wherein O2 or H2, or both, are introduced intermittently over the length of the catalytic bed or the length of the reaction zone. Embodiment 8 is the method of any one of embodiments 1 to 7, wherein H2 is introduced gradually over the length of the catalytic bed or the length of the reaction zone in a second reactant feed stream through a membrane that is positioned proximate to the catalytic bed. Embodiment 9 is the method of embodiment 8, wherein O2 is introduced over the length of the catalytic bed or the length of the reaction zone in a third feed stream through a second membrane that is positioned proximate to the catalytic bed. Embodiment 10 is the method of embodiment 8, wherein O2 is introduced with the propene in the first reactant feed stream. Embodiment 11 is the method of any one of embodiments 1 to 7, wherein O2 is introduced gradually over the length of the catalytic bed or the length of the reaction zone in a second reactant feed stream through a membrane that is positioned proximate to the catalytic bed. Embodiment 12 is the method of embodiment 11, wherein H2 is introduced with the propene in the first feed stream. Embodiment 13 is the method of any one of embodiments 1 to 12, wherein the first reactant feed stream further comprises an inert gas. Embodiment 14 is the method of embodiment 13, wherein the inert gas is helium, nitrogen, argon, water vapor, carbon dioxide or any combination thereof. Embodiment 15 is the method of any one of embodiments 1 to 14, wherein the reaction conditions include a weight hourly space velocity (WHSV) of between 1 and 200 h−1. Embodiment 16 is the method of any one of embodiments 1 to 15, wherein the product stream further comprises water. Embodiment 17 is the method of any one of embodiments 1 to 16, wherein the propene epoxidation catalyst comprises titanium, gold, palladium, platinum or any combination or alloy thereof. Embodiment 18 is the method of embodiment 17, wherein the propene epoxidation catalyst is supported with a metal oxide or a zeolite. Embodiment 19 is the method of any one of embodiments 1 to 18, wherein the propene epoxidation catalyst is in particulate form or formed to have a selected shape. Embodiment 20 is the method of any one of embodiments 1 to 19, wherein the first reactant feed stream is introduced through an inlet positioned upstream from the catalytic bed. Embodiment 21 is the method of any one of embodiments 1 to 20, wherein the separate reactant feed stream that gradually introduces O2 or H2, or both, over the length of the catalytic bed or the length of the reaction zone is introduced through a second inlet that is positioned downstream from the first inlet. Embodiment 22 is the method of embodiment 21, wherein the hydrogen gas is gradually introduced over the length of the catalytic bed or the length of the reaction zone through a second inlet that is positioned downstream from the first inlet. Embodiment 23 is the method of embodiment 22, wherein the oxygen gas is introduced over the length of the catalytic bed or the length of the reaction zone through a third inlet that is positioned downstream from the first inlet. Embodiment 24 is the method of any one of embodiments 1 to 23, wherein the reactor comprises alternating plates or tubes of an oxygen feed plate or tube, an epoxidation catalyst plate or tube, and a hydrogen feed plate or tube. Embodiment 25 is the method of any one of embodiments 1 to 24, wherein the reaction zone is a continuous flow reactor selected from a fixed-bed reactor, a fluidized reactor, a plate or tube reactor, a membrane reactor or a moving bed reactor.
Embodiment 26 is a method for direct epoxidation of propene without using hydrogen gas (H2) as a reactant, the method comprising reacting, in a reaction zone of a reactor, propene and oxygen gas (O2) in the presence of a catalytic bed that includes a propene epoxidation catalyst to produce a product stream comprising propylene oxide, where at least 50 vol. % propene and 1 to 15 vol. % O2 is maintained in the reaction zone during the reaction by (i) introducing the propene through a first reactant feed stream and (ii) gradually introducing the O2 over the length of the catalytic bed or the length of the reaction zone through a separate reactant feed stream; a temperature of 150° C. to 300° C. and a pressure of 3 bar to 20 bar is maintained in the reaction zone during the reaction; and the direct epoxidation of propene reaction is performed in the absence of H2 gas. Embodiment 27 is the method of embodiment 26, wherein 82 vol. % to 95 vol. % of propene and 3 vol. % to 8 vol. % O2 is maintained in the reaction zone during the reaction. Embodiment 28 is the method of embodiment 26, wherein 88 vol. % to 92 vol. % of propene and 4 vol. % to 6 vol. % O2 is maintained in the reaction zone during the reaction. Embodiment 29 is the method of any one of embodiments 26 to 28, wherein the vol. % of propene and O2 in the reaction zone has an explosive regime, and wherein the gradual introduction of O2 in the reaction zone is such that an explosive concentration of propene and O2 is not exceeded at any point throughout the length of the reaction zone. Embodiment 30 is the method of any one of embodiments 26 to 29, wherein a temperature of 200° C. to 275° C. and a pressure of 5 bar to 15 bar is maintained in the reaction zone during the reaction. Embodiment 31 is the method of any one of embodiments 26 to 30, wherein O2 is introduced incrementally or intermittently over the length of the catalytic bed or the length of the reaction zone. Embodiment 32 is the method of any one of embodiments 26 to 30, wherein O2 is introduced gradually over the length of the catalytic bed or the length of the reaction zone in a second reactant feed stream through a membrane that is positioned proximate to the catalytic bed. Embodiment 33 is the method of any one of embodiments 26 to 32, wherein the first reactant feed stream further comprises an inert gas. Embodiment 34 is the method of embodiment 33, wherein the inert gas is helium, nitrogen, argon, carbon dioxide or any combination thereof. Embodiment 35 is the method of any one of embodiments 26 to 34, wherein the reaction conditions include a weight hourly space velocity (WHSV) of between 1 and 200 h−1. Embodiment 36 is the method of any one of embodiments 26 to 35, wherein the product stream further comprises water. Embodiment 37 is the method of any one of embodiments 26 to 36, wherein the propene epoxidation catalyst comprises titanium, gold, palladium, platinum or any combination or alloy thereof. Embodiment 38 is the method of embodiment 37, wherein the propene epoxidation catalyst is supported with a metal oxide or a zeolite. Embodiment 39 is the method of any one of embodiments 26 to 38, wherein the propene epoxidation catalyst is in particulate form or formed to have a selected shape. Embodiment 40 is the method of any one of embodiments 26 to 39, wherein the first reactant feed stream is introduced through an inlet positioned upstream from the catalytic bed. Embodiment 41 is the method of any one of embodiments 26 to 40, wherein the separate reactant feed stream that gradually introduces O2 over the length of the catalytic bed or the length of the reaction zone is introduced through a second inlet that is positioned downstream from the first inlet. Embodiment 42 is the method of any one of embodiments 26 to 41, wherein the reactor comprises alternating plates or tubes of an oxygen gas feed plate or tube and an epoxidation catalyst plate or tube. Embodiment 43 is the method of any one of embodiments 26 to 42, wherein the reaction zone is a continuous flow reactor selected from a fixed-bed reactor, a fluidized reactor, a plate or tube reactor, a membrane reactor or a moving bed reactor.
The following includes definitions of various terms and phrases used throughout this specification.
The terms “propene” and “propylene” refer to a compound having the structure CH3CH═CH2.
The term “inert” is defined as chemically inactive or substantially inactive under the reaction conditions. Non-limiting examples of inert chemical compounds in the context of this invention include helium, nitrogen, argon, and carbon dioxide.
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%.
The term “substantially” and its variations are defined to include ranges within 10%, within 5%, within 1%, or within 0.5%.
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.
The term “effective,” as that term is used in the specification and/or claims, means adequate to accomplish a desired, expected, or intended result.
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 of material, or total moles, that includes the component unless otherwise stated. In a non-limiting example, 10 grams of component in 100 grams of the material is 10 wt. % of component.
The use of the words “a” or “an” when used in conjunction with any of the terms “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 methods of the present invention can “comprise,” “consist essentially of,” or “consist of” particular ingredients, components, compositions, etc. disclosed throughout the specification. With respect to the transitional phrase “consisting essentially of,” in one non-limiting aspect, a basic and novel characteristic of the methods of the present invention is the ability to safely produce of propylene oxide under reaction conditions that include (1) at least 50 vol. % propene, 1 to 15 vol. % O2, and optionally 1 to 15 vol. % H2 and (2) a temperature of 150° C. to 300° C. and a pressure of 3 bar to 20 bar.
Other objects, features and advantages of the present 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 one embodiment may be combined with features from any of the other embodiments. In further embodiments, additional features may be added to the specific embodiments described herein.
Advantages of the present invention may become apparent to those skilled in the art with the benefit of the following detailed description and upon reference to the accompanying drawings.
While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and may herein be described in detail. The drawings may not be to scale.
The currently available methods to produce propylene oxide from propene are inefficient and suffer from catalyst deactivation. A discovery has been made that allows increased amounts of propene, oxygen, and optionally, hydrogen, to be used in a safe manner in a commercial reactor setting rather than on an experimental reactor setting (e.g., micro reactors). The discovery is premised on the idea of maintaining, in the reaction zone during the reaction, at least 50 vol. % propene, 1 to 15 vol. % O2, and optionally 1 to 15 vol. % H2, at high temperatures (e.g., 150° C. to 300° C., preferably 200° C. to 275° C.) and pressures (3 bar to 20 bar, preferably 5 bar to 15 bar) by gradually introducing a feed stream that includes O2 or multiple feed streams that each include O2 and H2 over the length of the catalytic bed or the length of the reaction zone. Without wishing to be bound by theory, it is believed that increasing the concentration of the propene and the oxygen at the catalyst surface will produce more propylene oxide and fewer by-products (e.g., water and/or acrolein). By controlling the position and the addition of the reactant gases to the catalytic bed, the reaction can be run at, outside of, or near the explosive regime for mixtures of propene, oxygen and hydrogen proximate or in the catalytic bed, while not exceeding the explosive concentration at any one point throughout the length of the reaction zone.
These and other non-limiting aspects of the present invention are discussed in further detail in the following sections with reference to the Figures.
Methods for direct epoxidation of propene are described. The methods can include introducing reactant feeds at different positions and times in the reaction zone such that the total concentration of reactants in the reaction zone are above the explosive regime of the reactant gases, while not exceeding the explosive concentration of the reactant gases at any point throughout the length of the reaction zone. The reaction zone can be a continuous flow reactor selected from a fixed-bed reactor, a fluidized reactor, a plate reactor, a membrane reactor or a moving bed reactor. Non-limiting examples of continuous flow reactors are described in U.S. Pat. No. 6,977,064 to Adris et al., U.S. Pat. No. 7,445,758 to Adris et al., and U.S. Pat. No. 8,288,311 to Dhingra et al. Details about non-limiting reactors are provided in the figures.
Referring to
In the reaction zone, propene reacts with oxygen to produce propylene oxide. When the catalyst includes gold and titania, hydrogen can react with the gold-titania species to form a peracid species (e.g., Ti—OOH species). The peracid can then react with the olefin to form propylene oxide. In other embodiments, the hydrogen can reduce the metal back to its metal state. In some embodiments, hydrogen is not used (e.g.,
Referring to
Another embodiment of the invention relates to a continuous flow chemical reaction fluidized bed system 300 as shown in
In some embodiments, the conduits that introduce the oxygen and hydrogen into the reactor are perpendicular to the flow of the propylene feed stream. System 400 includes reactor 302 and a catalyst capable of catalyzing a propylene oxide reaction. Reactor 302 includes fluidized catalytic bed 304 having a height and having first feed (propene) inlet 306 at a lower end for a first feed stream (propene feed stream) and product outlet 308 for the product stream (propylene oxide stream) at an upper end. The first feed stream (propene feed stream) can include propene and oxygen. Fluidized catalytic bed 304 can include interior conduits 402 and 404 extending perpendicular within the fluidized catalytic bed.
In some embodiments, the catalytic bed in the continuous flow reactor is separated into several catalytic beds.
In some embodiments, a porous barrier reactor is used to provide oxygen gas and/or hydrogen gas to the catalytic bed. Porous barrier reactor system 600 is shown in
In
Any catalyst capable of catalyzing the propylene oxide reaction can be used. One or more of the catalysts of the current embodiments can include a supported catalyst or bulk metal catalyst that contains metals (e.g., metals in reduced form), metal compounds (e.g., metal oxides) or mixtures thereof (collectively “metals”) of gold (Au), silver (Ag), titanium (Ti), platinum (Pt), palladium (Pd) or combinations thereof. The amount of catalytic metal to be used can depend, inter alia, on the catalytic activity of the catalyst. In some embodiments, the amount of catalytic metal present in the catalyst can range from 0.01 to 100 parts by weight of catalytic metal per 100 parts by weight of catalyst, from 0.01 to 5 parts by weight of catalytic metal per 100 parts by weight of catalyst. If more than one catalytic metal is used, the molar percentage of one metal can be 1 to 99 molar % of the total moles of catalytic metals in the catalyst. The metals can be supported on silica dioxide (SiO2) or a support that includes Ti in the crystalline SiO2 structure. Non-limiting examples of such supports include, zeolites TS-1 or Ti-Beta, which can be obtained commercially or manufactured.
The components of the first, second and third feed streams can be obtained from other process units and/or from commercial sources. The propene feed stream (first feed stream) can include at least 50 vol. %, or 82 vol. % to 95 vol. %, or 88 vol. % to 92 vol. % or 50 vol. %, 51 vol. %, 52 vol. %, 53 vol. %, 54 vol. %, 55 vol. %, 56 vol. %, 57 vol. %, 58 vol. %, 59 vol. %, 60 vol. %, 61 vol. %, 62 vol. %, 63 vol. %, 64 vol. %, 65 vol. %, 66 vol. %, 67 vol. %, 68 vol. %, 69 vol. %, 70 vol. %, 71 vol. %, 72 vol. %, 73 vol. %, 74 vol. %, 75 vol. %, 76 vol. %, 77 vol. %, 78 vol. %, 79 vol. %, 80 vol. %, 81 vol. %, 82 vol. %, 83 vol. %, 84 vol. %, 85 vol. %, 86 vol. %, 87 vol. %, 88 vol. %, 89 vol. %, 90 vol. %, 91 vol. %, 92 vol. %, 93 vol. %, 94 vol. %, 95 vol. %, or any value or range there between of propene with the balance being an inert gas, oxygen, hydrogen or combinations thereof. In some instances, gases inert to the propylene oxide reaction can be mixed with the propene. Such gases include carbon dioxide, nitrogen, helium or argon or combinations thereof. The oxygen stream (second feed stream) can include at least 50 vol. %, or 82 vol. % to 95 vol. %, or 88 vol. % to 92 vol. % or 50 vol. %, 51 vol. %, 52 vol. %, 53 vol. %, 54 vol. %, 55 vol. %, 56 vol. %, 57 vol. %, 58 vol. %, 59 vol. %, 60 vol. %, 61 vol. %, 62 vol. %, 63 vol. %, 64 vol. %, 65 vol. %, 66 vol. %, 67 vol. %, 68 vol. %, 69 vol. %, 70 vol. %, 71 vol. %, 72 vol. %, 73 vol. %, 74 vol. %, 75 vol. %, 76 vol. %, 77 vol. %, 78 vol. %, 79 vol. %, 80 vol. %, 81 vol. %, 82 vol. %, 83 vol. %, 84 vol. %, 85 vol. %, 86 vol. %, 87 vol. %, 88 vol. %, 89 vol. %, 90 vol. %, 91 vol. %, 92 vol. %, 93 vol. %, 94 vol. %, 95 vol. %, or any range or value there between of oxygen with the balance being a gas inert to the system (e.g., carbon dioxide, nitrogen, helium, or argon). The third stream (hydrogen feed stream) can include at least 50 vol. %, or 82 vol. % to 95 vol. %, or 88 vol. % to 92 vol. % or 50 vol. %, 51 vol. %, 52 vol. %, 53 vol. %, 54 vol. %, 55 vol. %, 56 vol. %, 57 vol. %, 58 vol. %, 59 vol. %, 60 vol. %, 61 vol. %, 62 vol. %, 63 vol. %, 64 vol. %, 65 vol. %, 66 vol. %, 67 vol. %, 68 vol. %, 69 vol. %, 70 vol. %, 71 vol. %, 72 vol. %, 73 vol. %, 74 vol. %, 75 vol. %, 76 vol. %, 77 vol. %, 78 vol. %, 79 vol. %, 80 vol. %, 81 vol. %, 82 vol. %, 83 vol. %, 84 vol. %, 85 vol. %, 86 vol. %, 87 vol. %, 88 vol. %, 89 vol. %, 90 vol. %, 91 vol. %, 92 vol. %, 93 vol. %, 94 vol. %, 95 vol. %, or any range or value there between of hydrogen with the balance being an inert gas (e.g., carbon dioxide, nitrogen, helium, or argon). In some embodiments, the reactant gas streams include water vapor. In some embodiments, the second and third streams can have a minimal amount of reactant gas or be substantially devoid of reactant gas when exiting the reactor. In some embodiments, the delivery of the hydrogen and/or oxygen is adjusted based on the total amount of propylene, hydrogen and/or oxygen in the catalytic bed or the reactor. The delivery of the hydrogen and/or oxygen can be sequential and/or simultaneous through the various injectors and/or conduits. The flowrate of these streams can be tuned to exactly make up the hydrogen and oxygen consumed by the reaction, so that concentrations of the gases is outside of the explosive regime over the entire reactor length, while keeping these concentrations as high as allowed and not letting hydrogen or oxygen be depleted too much.
The product stream can include hydrogen, propylene oxide, water, alkenes and, in some instances, epoxide ring opening by-products. As described above the hydrogen and alkene oxides can be separated from the product stream. These propylene oxide can be isolated, sold or used in a variety of chemical applications. For example, propylene oxide can be used to make polyether polyols, propylene glycols, and propylene glycol ethers. Propylene oxides can also be used in the manufacture of flame retardants, modified carbohydrates, synthetic lubricants, oil field drilling chemicals, textile surfactants and the like.
The present invention will be described in greater detail by way of specific examples. The following examples are offered for illustrative purposes only, and are not intended to limit the invention in any manner. Those of skill in the art will readily recognize a variety of noncritical parameters which can be changed or modified to yield essentially the same results.
Computer simulated calculations based on the reaction kinetics of the epoxidation and water formation reactions were performed to compare a conventional method of producing propylene oxide from propylene, hydrogen and oxygen using a single stage reactor without interstaged feed addition and the method of the present invention using a 3-stage reactor with interstaged feed addition. For all the calculations, the kinetic rate expressions used were of a catalyst similar to the one reported by Chen et al. (Chem. Cat. Chem. 2013, 5, 467-478), which was a 0.05 wt % gold catalyst on an amorphous silica support on which 0.2 wt % Ti is deposited.
A 3 stage reactor was modeled. In each reactor stage 5 gram of catalyst was loaded. Operating conditions included: a pressure of 10 bar(a) and a reaction temperature of 483 K (210° C.). The feed rate to the first reactor was 1.12×10−4 mol/s of propene (152 Nml/min), 6.21×10−6 mol/s of hydrogen (8.5 N ml/min) and 6.21×10−6 mol/s of oxygen (8.5 Nml/min). The product composition leaving this reactor was: 1.10×10−4 mol/s of propene, 2.58×10−6 mol/s of hydrogen, 3.42×10−6 mol/s of oxygen, 1.95×10−6 mol/s of propene oxide, and 3.63×10−6 mol/s of water. This corresponded to a propene oxide yield (based on propene) of 1.75% and a hydrogen utilization efficiency of 53.9%.
Before the second stage, the hydrogen and oxygen feed streams were supplemented to the original molar flow rates of 6.21×10−6, i.e. feeding 1.10×10−4 mol/s propene, 6.21×10−6 mol/s hydrogen, 6.21×10−6 mol/sec oxygen, 1.95×10−6 mol/s propene oxide, and 3.63×10−6 mol/s of water. The product composition of the 2nd stage was: 1.08×10−4 mol/s of propene, 2.52×10−6 mol/s of hydrogen, 3.37×10−6 mol/s of oxygen, 3.93×10−6 mol/s of propene oxide, and 7.32×10−6 mol/s of water. This corresponded to a propene oxide yield (based on propene) of 3.51% and a hydrogen utilization efficiency of 53.6%.
Finally, before the third stage, the hydrogen and oxygen feed streams are again supplemented to the original molar flow rates of 6.21×10−6 mol/s, i.e. feeding 1.08×10−4, 6.21×10−6, 6.21×10−6, 3.93×10−6, and 7.32×10−6 mol/s for propene, hydrogen, oxygen, propene oxide and water. The product composition of the 3rd stage was: 1.06×10−4 mol/s of propene, 2.45×10−6 mol/s of hydrogen, 3.33×10−6 mol/s of oxygen, 5.93×10−6 mol/s of propene oxide, and 1.11×10−5 mol/s of water. This corresponded to a final propene oxide yield (based on propene) of 5.30% and a hydrogen utilization efficiency of 53.4%.
A single reactor containing 15 gram of catalyst was modeled taken without any interstaged feed addition. The original feed of the first reactor described above was used and the hydrogen and oxygen added before the subsequent reactors were omitted to prevent mixing of explosive gas compositions. The feed rate to the reactor was 1.12×10−4 mol/s (152 Nml/min) of propene, 6.21×10−6 mol/s of hydrogen (8.5 Nml/min) and 6.21×10−6 mol/s of oxygen (8.5 Nml/min). The product composition leaving this reactor is: 1.08×10−4 mol/s of propene, 8.58×10−8 mol/s of hydrogen, 1.40×10−6 mol/s of oxygen, 3.49×10−6 mol/s of propene oxide and 6.13×10−6 mol/s of water. This corresponded to a propene oxide yield (based on propene) of 3.12% and a hydrogen utilization efficiency of 57.0%.
From the calculations, it can be concluded that the staged reactor method resulted in a significant improvement of the product yield in a same sized reactor with an identical amount of catalyst (5.30% yield versus 3.12% yield). Furthermore, in the comparative single reactor, after 15 grams of catalyst, the hydrogen provided was almost entirely consumed, providing a larger amount of catalyst will therefore not increase the propene oxide yield, whereas in the method of the present invention, a higher conversion can be obtained by adding subsequent staged (i.e. after a 4th reactor containing another 5 grams of catalyst would result in a 7.11% propene oxide yield at 53.3% hydrogen efficiency).
This application claims the benefit of priority of U.S. Provisional Patent Application No. 62/289,626, filed Feb. 1, 2016, which is hereby incorporated by reference in its entirety.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/IB2016/057908 | 12/21/2016 | WO | 00 |
| Number | Date | Country | |
|---|---|---|---|
| 62289626 | Feb 2016 | US |
