Methods for preparing olefin metathesis catalysts for improved stability

Abstract

Provided here are methods for producing a shaped metal-supported catalyst. One such method includes the steps of mixing a support hydroxide with an aqueous mixture of an active metal compound to form a malleable mixture of an active metal incorporated support hydroxide, passing the malleable mixture through a molding device to produce a shaped metal-supported wet catalyst; and drying and calcining the shaped metal-supported wet catalyst. The support hydroxide contains one or more of aluminium hydroxide, silica hydroxide, zirconia hydroxide, cerium hydroxide, titanium hydroxide, lanthanum hydroxide, gallium hydroxide, or niobium hydroxide. The active metal compound can be one or more of vanadium, niobium, tantalum, chromium, molybdenum, tungsten, manganese, technetium, and rhenium.

Description

METHODS FOR PREPARING OLEFIN METATHESIS CATALYSTS FOR IMPROVED STABILITY Cross-Reference to Related Applications

[0001] This application claims priority to and the benefit of European Application No. EP24164732.0, filed on March 20, 2024. The contents of the referenced application are incorporated into the present application by reference.Technical Field

[0002] The disclosure relates to methods for the preparation of an olefin metathesis catalyst containing rhenium oxide and aluminium oxide.Background

[0003] The need for propylene has dramatically increased in recent years in order to supply the expanding markets for acrylic acid, polypropylene, and propylene oxide. The majority of propylene generated nowadays is by either fluid catalytic cracking (FCC) units or steam cracking units, which predominantly produce ethylene. A sudden spike in the demand for propylene cannot be managed by these procedures. To change the composition of a pool of low-value butenes to satisfy the market's need for propylene, olefin metathesis would be an advantageous process. Olefin metathesis is the catalytic twofold disproportionation of the two olefin molecules' carbon double bonds through cleavage and reformation. The distribution of the overall product is constrained by thermodynamic equilibrium in this reversible reaction. Catalytic olefin metathesis transforms simple and cheap organic molecules into complex and valuable molecules. In olefin metathesis, two olefin molecules exchange the groups around the double bonds in the presence of a catalyst. The olefins can be of different compounds by structure and composition, or two identical compounds. In general, reaction temperatures for olefin metathesis reactions can be as low as atroom temperature or can be at temperatures up to about 500 °C or greater, depending on the type of feed stock, the catalyst, and the media in which the reaction is conducted. To produce propylene and other products, however, olefin metathesis catalysts frequently lack the necessary selectivity. As a result of coking from aromatic compounds, olefin metathesis catalysts can also become inactive. In industrial applications, metathesis catalysts require both high catalytic activities at low reaction temperatures and long lifetime.Summary

[0004] Applicant has identified a necessity for the development of highly selective and stable catalyst for metathesis reactions of butenes to propene and internal olefins. Provided here are compositions and methods to address these shortcomings of the art and provide other additional or alternative advantages.

[0005] Embodiments include methods for producing a shaped metal-supported catalyst. One such method includes the steps of mixing a support hydroxide with an aqueous mixture of an active metal compound to form a malleable mixture of an active metal incorporated support hydroxide, passing the malleable mixture through a molding device to produce a shaped metal-supported catalyst; drying the shaped metal-supported wet catalyst at about 100 °C to about 200 °C; and calcining the shaped metal-supported dry catalyst at about 400 °C to about 1000 °C. One such shaped metal-supported catalyst contains gamma alumina.

[0006] In certain examples, the support hydroxide contains one or more of aluminium hydroxide, silica hydroxide, zirconia hydroxide, cerium hydroxide, titanium hydroxide, lanthanum hydroxide, gallium hydroxide, or niobium hydroxide. In certain examples, the support hydroxide contains aluminium hydroxide. In certain examples, the active metal compound can be one or more of vanadium, niobium, tantalum, chromium, molybdenum, tungsten, manganese, technetium,rhenium, iron, cobalt, nickel, ruthenium, rhodium, iridium, osmium, palladium, and platinum. In certain examples, the active metal compound is a rhenium metal compound or ruthenium metal compound or a combination thereof. In certain examples, the shaped metal-supported catalyst is dried at about at about 100 °C to about 200 °C. In certain examples, the shaped metal- supported catalyst is calcined at about 450 °C to about 700 °C. Embodiments of the disclosure include a shaped metal-supported catalyst made by the foregoing process. Embodiments of the disclosure include a shaped metal- supported catalyst containing an active metal compound and the support oxide. One such shaped metal-supported catalyst is based on aluminium hydroxide as the support hydroxide. One such shaped metal-supported catalyst contains a rhenium compound or a ruthenium compound or a combination thereof as the active metal compound. One such shaped metal-supported catalyst contains gamma alumina.Brief Description of the Drawings

[0007] Examples will be readily understood by the following detailed description in conjunction with the accompanying drawings. To facilitate this description, like reference numerals designate like structural elements or procedures in a method. Examples are illustrated by way of example and not by way of limitation in the accompanying drawings. The present disclosure can be better understood by referring to the following figures. These drawings illustrate the principles of the disclosure and no limitation of the scope of the disclosure is thereby intended.

[0008] FIG. 1 is a diagrammatic representation of a method of preparing an extruded metal- supported catalyst, according to an example.

[0009] FIGS. 2A and 2B are diagrammatic representations of an extruded metal-supported catalyst as compared to another rhenium oxide-containing catalyst, according to an example.Detailed Description

[0010] The present disclosure describes various examples related to methods of production of olefin metathesis catalysts. By way of example, these olefin metathesis catalysts may be utilized in a metathesis unit that houses a reactor containing the metathesis catalyst within. Embodiments include methods for producing a shaped metal-supported catalyst. One such method for producing a shaped metal-supported catalyst includes the following steps: mixing a support hydroxide with an aqueous mixture of an active metal compound to form a malleable mixture of an active metal incorporated support hydroxide; passing the malleable mixture through a molding device to produce a shaped metal-supported catalyst; drying the shaped metal-supported wet catalyst; and calcining the shaped metal-supported dry catalyst in an oxidizing environment. In certain examples, the shaped metal-supported catalyst is dried at temperatures between 100 °C and 200 °C. In certain examples, the shaped metal- supported catalyst is calcined in the oxidizing environment at temperatures between 400 °C and 1000 °C. In certain examples, the shaped metal- supported catalyst is calcined in the oxidizing environment at temperatures between 450 °C and 700 °C. In certain examples, the support hydroxide can be one or more of aluminium hydroxide, silica hydroxide, zirconia hydroxide, cerium hydroxide, titanium hydroxide, lanthanum hydroxide, gallium hydroxide, or niobium hydroxide. In certain examples, the support hydroxide is aluminium hydroxide. In certain examples, the active metal compound contains one or more of vanadium, niobium, tantalum, chromium, molybdenum, tungsten, manganese, technetium, rhenium, iron, cobalt, nickel, ruthenium, rhodium, iridium, osmium, palladium, and platinum. In certain examples, the active metal compound is a rhenium compound or a ruthenium compound or a combination thereof. In certain examples, the molding device is an extrusion device, a spheronization device, or a combination thereof. In certain examples, the aqueous mixture of theactive metal comprises an acidic additive.

[0011] Embodiments include a shaped metal-supported catalyst made by the methods described herein. In certain examples of the shaped metal-supported catalyst, the support hydroxide is aluminium hydroxide. In certain examples of the shaped metal-supported catalyst, the active metal compound is a rhenium compound or a ruthenium compound or a combination thereof. In certain examples of the shaped metal- supported catalyst, the active metal compound is rhenium oxide. Certain examples of the shaped metal-supported catalyst contain gamma alumina.

[0012] An example of a method for producing a catalyst includes the steps of contacting a support hydroxide with an active metal compound to provide an active metal incorporated support hydroxide. The support hydroxide can be one or more of aluminium hydroxide, silica hydroxide, zirconia hydroxide, cerium hydroxide, titanium hydroxide, lanthanum hydroxide, gallium hydroxide, or niobium hydroxide. In certain embodiments, the support hydroxide is aluminium hydroxide. In certain embodiments, the active metal compound is one or more of a Group 5, 6, 7, or 8 metal compound. In certain specific embodiments, the active metal compound may be selected from a group within Group 5, 6, 7, or 8 metals. For example, the active metal compound may be selected from Group 5, 6, or 7. In another example, the active metal compound may be selected from Group 5 or 6, Group 6 or 7, or Group 5 or 7. In certain embodiments, the active metal compound is one or more of vanadium, niobium, tantalum, chromium, molybdenum, tungsten, manganese, technetium, rhenium, iron, cobalt, nickel, ruthenium, rhodium, iridium, osmium, palladium, and platinum. In another embodiment, the active metal compound is one or more of vanadium, niobium, tantalum, chromium, molybdenum, tungsten, manganese, technetium, and rhenium. Examples of the active metal compound can be rhenium compound or ruthenium compound or a combination thereof. In still another example, the active metal compound maycontain rhenium. Examples of the active metal compound can be rhenium oxide or ruthenium oxide. In another example, the active metal compound can be rhenium oxide.

[0013] In the following description, reference is made to the accompanying drawings that form a part of this disclosure and numerous details are set forth in order to provide a thorough understanding of the various examples. In other instances, well-known processes, devices, and systems may not been described in particular detail in order not to unnecessarily obscure the various examples. Additionally, illustrations of the various examples may omit certain features or details in order to not obscure the various examples. The drawings may provide an illustration of some of the various examples in which the subject matter of the present disclosure may be practiced. Other examples may be utilized, and logical changes may be made without departing from the scope of this disclosure.

[0014] The description may use the phrases “in some examples,” “in various examples,” “in an example,” or “in examples,” which may each refer to one or more of the same or different examples. 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.

[0015] The term “about” refers to a range of values including the specified value, which a person of ordinary skill in the art would consider reasonably similar to the specified value. In examples, “about” refers to values within a standard deviation using measurements generally acceptable in the art. In one non-limiting example, when the term “about” is used with a particular value, then “about” refers to a range extending to ±10% of the specified value, alternatively ±5%of the specified value, or alternatively ±1% of the specified value, or alternatively ±0.5% of the specified value. In examples, “about” refers to the specified value.

[0016] Examples of the shaped metal- supported catalysts include olefin metathesis catalysts containing rhenium oxide and aluminium oxide. An example of a method of preparation of these olefin metathesis catalysts includes the steps of mixing aluminum hydroxide with a rhenium compound solution to form a thick and malleable mixture and molding the mixture into a sphere or an extrudate, and subjecting the sphere or the extrudate to a heat treatment in the presence of air to convert the aluminum hydroxide in the sphere or the extrudate to a transition alumina. The method further includes the step of calcining the contacted support hydroxide in an atmosphere containing oxygen to yield the shaped metal- supported catalyst. In certain examples, the molding step can be an extrusion process, a spheronization process, or a combination thereof. In certain examples, the molding step can be a pelletization process.

[0017] There are 3 types of surface -OH' groups available on the surface of the alumina. During the catalyst synthesis, the rhenium ions readily occupy the basic -OH' groups of the active support, then occupy the neutral -OH' groups of the active support, and finally the acidic -OH' groups of the active support. At the same time, the metathesis catalyst activity / stability depends mainly on the ReO4‘ ions bonded with acidic — OH' sites rather than the basic and neutral -OH groups.

[0018] Embodiments include a method of producing rhenium-alumina catalysts. The steps include mixing aluminum hydroxide and a rhenium metal precursor to form a thick and malleable mixture and molding the mixture into a sphere or an extrudate, and subjecting the sphere or the extrudate to a heat treatment in the presence of air to convert the aluminum hydroxide in the sphere or the extrudate to a transition alumina. One such extruded metal-supported catalyst contains gamma alumina. Here, incorporation of aluminum hydroxide along with rhenium precursor leadsto formation of a highly dispersed rhenium oxide by interaction of aluminium ions with rhenium ions during the drying and calcination process. The rhenium oxide loaded on the support sinters during the regeneration process. As the rhenium ions impact the surface layer of the pores of the extrudate, they can cause particles on the surface to move, leading to a rearrangement or densification of the particle structure. This process can change the characteristics of the surface layer, such as its density, smoothness, hardness, or other physical properties. However, in the case of co-extrusion process, due to strong interaction between the support and the rhenium oxide, the catalyst stability can be enhanced by providing a barrier for mobility of rhenium oxide.

[0019] Methods disclosed herein increase the acidic -OH' groups on the surface of the support. Mixing an aluminium hydroxide and a rhenium precursor to form a thick and malleable mixture changes the availability of the -OH' groups as compared to catalysts made by impregnating the rhenium ions on the pre-formed alumina support. In certain examples, the aqueous mixture of the rhenium precursor contains an acidic additive. After extrusion, during the heat treatment, initially, the mixed aluminium hydroxide present along with rhenium metal precursor produce an amorphous aluminum oxide. Further heat treatment, the amorphous aluminium oxide converts to a crystallized aluminium oxide support with rhenium oxide. As the aluminium oxide and rhenium oxide were mixed together before calcination (during the extrusion), the active rhenium oxide may be present on the surface of the support or buried inside the support or fully merged with the support. The coverage of rhenium oxide on the alumina support surface will be less and there will be an increased formation of — OH' groups. More acidic — OH' groups are formed and the basic and neutral -OH sites are reduced on the support surface, which leads to formation of strong metal support interactions and high dispersion of the rhenium oxide.

[0020] FIG. 1 is a diagrammatic representation of a method of preparing a y-alumina-basedcatalyst, according to an example. The method 100 of preparation of the catalyst involves the step 102 of dissolving a rhenium precursor in water to prepare an aqueous rhenium precursor solution and the step 104 of mixing aluminum hydroxide with the aqueous rhenium precursor solution to prepare a malleable mixture. The rhenium precursor solution is added to aluminum hydroxide based on a required volume sufficient to form a thick and malleable mixture. The nature of the thick and malleable mixture should be sufficient to make an extrudate. The method 100 further involves the step 106 of passing the malleable mixture through a molding device to produce an extruded metal-supported wet catalyst, the step 108 of drying the extruded metal-supported wet catalyst at about 100 °C to about 200 °C to prepare dry extrudates, and the step 110 of calcining the extruded metal-supported dry catalyst at about 400 °C to about 1000 °C in an oxidizing environment (such as air). In certain examples, the dry extrudates are calcined to get the desired phase of transition alumina. In some examples, the dry extrudates are calcined at about 450 °C to about 700 °C. FIG. 2A is a diagrammatic representation of a extruded rhenium-supported catalyst. As the aluminium oxide and rhenium oxide were mixed together before the extrusion, the active rhenium oxide moieties are present on the surface of the support and buried inside the support or fully merged with the support.

[0021] A comparative catalyst was made by a two-step impregnation method. This method includes the steps of forming an aluminium hydroxide sphere or extrudate followed by impregnation of the y-alumina support sphere or extrudate by a rhenium precursor solution. The formed wet impregnated aluminium oxide is dried at a desired temperature in air and finally calcined at required temperature to get the final catalyst. The method further includes degassing the y-alumina support at 300-400 °C under the flow of air and cooling the degassed support in a desiccator, followed by pore volume measurement. The amount of rhenium precursor solution forthe impregnation of the y-alumina support sphere or extrudate is based on the pore volume of gamma alumina support. The impregnation takes about 5 to 10 mins. The formed wet impregnated aluminium oxide is immediately transferred to a pre-heated glass tray for 6 to 12 hours in the air oven at 160 °C to remove the water. The impregnated aluminium oxide catalyst is calcined in a rotary furnace at 550 °C under the flowing air for 5 hours. FIG. 2B is a diagrammatic representations of a rhenium oxide-containing catalyst prepared by impregnation of the rhenium oxide after the alumina support has been extruded, according to a comparative example.

[0022] When ranges are disclosed herein, ranges from any lower limit may be combined with any upper limit to recite a range not explicitly recited, as well as, ranges from any lower limit may be combined with any other lower limit to recite a range not explicitly recited, in the same way, ranges from any upper limit may be combined with any other upper limit to recite a range not explicitly recited. Additionally, reference to values stated in ranges includes each and every value within that range, even though not explicitly recited. Thus, every point or individual value may serve as its own lower or upper limit combined with any other point or individual value or any other lower or upper limit, to recite a range not explicitly recited.

[0023] Other objects, features and advantages of the disclosure will become apparent from the foregoing drawings, detailed description, and examples. These drawings, detailed description, and examples, while indicating specific examples of the disclosure, are given by way of illustration only and are not meant to be limiting. In further examples, features from specific examples may be combined with features from other examples. For example, features from one example may be combined with features from any of the other examples. In further examples, additional features may be added to the specific examples described herein. It should be understood that although the disclosure contains certain aspects, examples, and optional features, modification, improvement,or variation of such aspects, examples, and optional features can be resorted to by those skilled in the art, and that such modification, improvement, or variation is considered to be within the scope of this disclosure.

Claims

Claims1. A method for producing a shaped metal-supported catalyst, the method comprising: mixing a support hydroxide with an aqueous mixture of an active metal compound selected from Group 5, 6, or 7 to form a malleable mixture of an active metal incorporated support hydroxide; passing the malleable mixture through a molding device to produce a shaped metal- supported wet catalyst; drying the shaped metal-supported wet catalyst to produce a shaped metal-supported dry catalyst; and calcining the shaped metal-supported dry catalyst in an oxidizing environment.

2. The method of Claim 1, wherein the shaped metal-supported wet catalyst is dried at temperatures between 100 °C and 200 °C.

3. The method of Claim 1, wherein the shaped metal-supported dry catalyst is calcined in the oxidizing environment at temperatures between 400 °C and 1000 °C.

4. The method of Claim 1, wherein the shaped metal-supported dry catalyst is calcined in the oxidizing environment at temperatures between 450 °C and 700 °C.

5. The method of Claim 1, wherein the support hydroxide contains one or more of aluminium hydroxide, silica hydroxide, zirconia hydroxide, cerium hydroxide, titanium hydroxide, lanthanum hydroxide, gallium hydroxide, or niobium hydroxide.

6. The method of Claim 1 , wherein the support hydroxide is aluminium hydroxide.

7. The method of Claim 1, wherein the active metal compound contains one or more of vanadium, niobium, tantalum, chromium, molybdenum, tungsten, manganese, technetium, and rhenium.

8. The method of Claim 1, wherein the active metal compound contains rhenium.

9. The method of Claim 1, wherein the molding device is an extrusion device, a spheronization device, or a combination thereof.

10. The method of Claim 1, wherein the aqueous mixture of the active metal comprises an acidic additive.

11. A system to produce metathesis reactions using a shaped metal-supported catalyst, the system comprising: a metathesis unit having a reactor, the reactor containing the shaped metal- supported catalyst made by the method of Claim 1.

12. The system of Claim 11, wherein the support hydroxide is aluminium hydroxide.

13. The system of Claim 11, wherein the active metal compound is a rhenium compound or a ruthenium compound or a combination thereof.

14. The system of Claim 11, wherein the active metal compound is rhenium oxide.

15. The system of Claim 11, further comprising gamma alumina.

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