ISOMERIZATION CATALYST

CROSS REFERENCE TO RELATED APPLICATIONS [0001] This application claims priority from US Provisional Application No. 62/439,579 filed December 28, 2016, hereby incorporated by reference in its entirety for all purposes.

BACKGROUND

[0002] Catalysts containing platinum on alumina can be useful in alkane isomerization reactions, such as the transformation of n-butane to iso-butane. Iso-butane is an important starting material for production of methyl tert-butyl ether (MTBE), a gasoline additive that can be used to raise the octane number of gasoline. During the catalyzed isomerization reaction, carbonaceous materials, sulfurous materials, and/or other materials (e.g., fouling metals) can be deposited on the catalyst surface resulting in masking of catalyst active sites. In addition, catalysts can undergo sintering of particles resulting in mutual cohesion that increases the particle size in the catalyst and decreases the dispersion of particles in the catalyst. Thus over time a loss in catalytic activity can be observed. It is desirable to periodically restore or rejuvenate catalyst activity.

SUMMARY

[0003] Embodiments of the invention are directed to a process for rejuvenating a devitalized alkane isomerization catalyst. In certain aspects the catalyst comprises platinum (Pt) on a chlorided alumina (Al) support or alumino-silicates with inorganic binder. In a particular aspect the catalyst is a C4 isomerization catalyst. In certain aspect a devitalized catalyst can comprise 0.1 to 10 weight percent platinum, 1 to 10 weight percent chlorine, and 0.05 to 2.0 weight percent carbon. In certain aspects the devitalized catalyst is fouled or spent and having reduced catalytic activity due to deposition of carbonaceous or sulfurous materials, or physical or chemical alterations. A fouled or spent Pt containing isomerization catalyst can be chemically treated to restore activity or to substantially improve the catalytic activity. As used herein the term "substantially" refers to restoration of activity to within 1 to 5% of the activity prior to devitalization. In certain aspects the catalyst is treated by contacting a devitalized catalyst with a first regenerant solution of (i) a basic alcoholic solution, (ii) an alkoxide solution in an organic solvent, or (iii) alkali metal chloride in an alcohol solvent at temperatures of 25 to 250 °C for a period of time. In certain aspects the basic alcohol solution comprises an inorganic base in a C2 to C4 alcohol, e.g., methanol, ethanol, or tert-butyl alcohol solution. In a further aspect the inorganic base is potassium hydroxide (KOH) or sodium hydroxide (NaOH). In certain aspects the alkoxide solution comprises an alkoxide in an organic solvent. The alkoxide can be a CI to C5 alkoxide. In certain aspects the alkoxide is a C4 alkoxide, such as ter-butoxide (e.g., sodium ter-butoxide). In a further aspect the alkoxide is sodium alkoxide (RONa) or potassium alkoxide (ROK) and the organic solvent is THF or tert-Butyl alcohol. The alkali metal chloride solution comprises an alkali metal chloride in an alcohol solvent. In particular aspects the alcohol solvent can be C2 to C4 alcohol. In certain aspect the alkali chloride is KC1 or NaCl and the alcohol solvent is methanol. The catalyst can be further treated with a second solution comprising chloro-organic compounds at a temperature of 50 to 550 °C. In certain aspects the chloro-organic compounds can be phosgene, chloro acetyl chloride, methylene chloride, dichloromethane, chloroform, or carbon tetrachloride.

[0004] Certain embodiments are directed to methods for rejuvenating an isomerization catalyst by removal of deposited carbonaceous or sulfurous material from a spent platinum/alumina catalyst, comprising (i) contacting the spent catalyst with at least one regeneration solution forming a processed spent catalyst, (ii) treating the processed spent catalyst with a second alcohol solution forming a treated spent catalyst; and (iii) treating the treated spent catalyst with a chloro-organic forming a regenerated catalyst. The regeneration solutions can be (a) an inorganic base in a first alcohol, (b) a solution of an alkoxide in an organic solvent, (c) a solution of an alkali metal chloride in alcohol, or (d) mixtures thereof. In certain aspects the regeneration solutions are at a concentration of 0.001, 0.01, or 0.1 to 1, 5, or 10 N. The spent catalyst is contacted with the regeneration solution(s) for 10, 20, 30, 40, 50, or 60 minutes or hours at a temperature of 25, 50, 75, 100, or 150 °C to 175, 200, 225, or 250 °C. In a further aspect the incubation can be carried out at a pressure of 1 to 10 bar. A second alcohol can be C2 to C4 alcohol and can be contacted with the processed catalyst for 10, 20, 30, 40, 50, or 60 minutes or hours at a temperature of 25, 50, 100, or 200 °C to 250, 300, 400, or 550 °C. The treated catalyst can be contacted with the chloro-organic for 10, 20, 30, 40, 50, or 60 minutes or hours at 50, 100, 200, or 250 °C to 300, 400, or 550 °C. In certain aspects the regenerated catalyst can have substantially greater activity for the isomerization of n-butane to iso-butane then said spent catalyst. In certain aspects a regenerated catalyst can have a once through n-butane conversion of 50 to 55% with a selectivity of at least 90%. A spent catalyst, for example, can have a once through n-butane yield of 38% or less. In certain aspects the inorganic base is an alkali metal hydroxide, including, but not limited to KOH or NaOH. In a further aspect the first or second alcohol solvent is independently methanol, ethanol, tert-butyl alcohol, or a mixture thereof. In certain instances the chloro-organic is phosgene, chloro acetyl chloride, methylene chloride, dichloromethane, chloroform, carbon tetrachloride, or a mixture thereof. Certain embodiments are directed to using the regenerated catalyst as an isomerization catalyst for the production of MTBE.

[0005] Other embodiments are directed to processes for converting n-butane to iso-butane for use in the production of MTBE including contacting a regenerated catalyst as described herein with n-butane under conditions for producing iso-butane.

[0006] Other embodiments of the invention are discussed throughout this application. Any embodiment discussed with respect to one aspect of the invention applies to other aspects of the invention as well and vice versa. Each embodiment described herein is understood to be embodiments of the invention that are applicable to all aspects of the invention. It is contemplated that any embodiment discussed herein can be implemented with respect to any method or composition of the invention, and vice versa. Furthermore, compositions and kits of the invention can be used to achieve methods of the invention.

[0007] The use of the word "a" or "an" when used in conjunction with the term "comprising" in the claims and/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."

[0008] Throughout this application, the term "about" is used to indicate that a value includes the standard deviation of error for the device or method being employed to determine the value.

[0009] The use of the term "or" in the claims is used to mean "and/or" unless explicitly indicated to refer to alternatives only or the alternatives are mutually exclusive, although the disclosure supports a definition that refers to only alternatives and "and/or."

[0010] As used in this specification and claim(s), 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.

[0011] In the context of the present invention, nine embodiments are now described. Embodiment 1 is a method for rejuvenating an isomerization catalyst by removal of deposited carbonaceous or sulfurous material from a spent catalyst containing platinum, and chlorine on an alumina support. The method includes the steps of processing said spent catalyst with at least one of a solution of an inorganic base in a first alcohol, a solution of an alkoxide in an organic solvent, a solution of an alkali metal chloride in methanol and mixtures thereof at a concentration of 0.001 to 10 N in the temperature range of 25°C to 250°C; then treating the processed spent catalyst with a second alcohol in the temperature range of 25 °C to 550 °C; and then treating the processed and treated spent catalyst with a chloro-organic in the temperature range of 50 °C to 550 °C to obtain a regenerated catalyst having substantially greater activity for the isomerization of n-butane to iso-butane then said spent catalyst. Embodiment 2 is the method in accordance with embodiment 1, wherein said isomerization catalyst prior to treatment contains 0.1 to 10 weight percent platinum relative to the total weight of the isomerization catalyst, 1 to 10 weight percent chlorine relative to the total weight of the isomerization catalyst, and 0.05 to 2.0 weight percent carbon relative to the total weight of the isomerization catalyst. Embodiment 3 is the method in accordance with any one of embodiments 1 to 2, wherein said inorganic base is an alkali metal hydroxide. Embodiment 4 is the method in accordance with any one of embodiments 1 to 3, wherein said inorganic base is KOH or NaOH. Embodiment 5 is the method in accordance with any one of embodiments 1 to 4, wherein said first alcohol is methanol, ethanol, tert-butyl alcohol, or a mixture thereof. Embodiment 6 is the method in accordance with any one of embodiments 1 to 5, wherein the second alcohol is methanol, ethanol, tert-butyl alcohol, or mixtures thereof. Embodiment 7 is the method in accordance with any one of embodiments 1 to 6, wherein said chloro-organic is phosgene, chloro acetyl chloride, methylene chloride, dichloromethane, chloroform, carbon tetrachloride, or a mixture thereof. Embodiment 8 is the method in accordance with any one of embodiments 1 to 7, wherein the regenerated isomerization catalyst is used in the production of MTBE.

[0012] Embodiment 9 is a process for converting n-butane to iso-butane for use in the production of MTBE. The process includes the steps of combining an isomerization catalyst containing platinum and chlorine on an alumina support with an alcoholic solution or an alkoxide solution to create a reaction mixture; wherein the alcoholic solution contains a first alcohol and an inorganic base, an alkali metal chloride, or mixtures thereof at a concentration of 0.001 to 10 N; and wherein the alkoxide solution contains an alkoxide of formula R-O-X and an organic solvent, wherein R is an alkane, O is oxygen, and X is an alkali earth metal selected from sodium and potassium; maintaining the reaction mixture at a temperature of 25 °C to 250 °C for a time sufficient to remove a carbonaceous or sulfurous material from the isomerization catalyst to form a regenerated isomerization catalyst; then combining the isomerization catalyst with a second alcohol at a temperature of 25 °C to 550 °C; then combining the isomerization catalyst with a chloro-organic at a temperature of 50 °C to 550 °C; and then combining the isomerization catalyst with n-butane to form iso-butane.

[0013] Other objects, features and advantages of the present invention will become apparent from the following detailed description. It should be understood, however, that the detailed description and the specific examples, while indicating specific embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.

DESCRIPTION OF TH E DRAWINGS

[0014] The following drawings form part of the present specification and are included to further demonstrate certain aspects of the present invention. The invention may be better understood by reference to one or more of these drawings in combination with the detailed description of the specification embodiments presented herein.

[0015] FIG. 1. General schematic of the rejuvenation process.

DESCRIPTION

[0016] Disclosed herein are methods for rejuvenating an isomerization catalyst used in the production of isobutene. In one embodiment, the method includes contacting an isomerization catalyst with one or more rejuvenation solutions. In certain aspect rejuvenation solutions include a first alcohol solution or an alkoxide solution. The rejuvenation solutions can be alcohol solutions and can contain alcohol as a solvent and an inorganic base, an alkoxide, an alkali metal chloride, or mixtures thereof. Isomerization catalysts that may be used in accordance with the disclosure include platinum supported catalyst. In some embodiments, the isomerization catalyst includes platinum on an alumina support. In a further aspect the catalyst may also contain palladium, rhodium, cobalt, nickel, iron, copper, molybdenum or combinations thereof. In certain aspects the isomerization catalyst can include platinum in an amount of 0.1 to 10 weight percent, relative the total weight of the isomerization catalyst. [0017] In certain aspects the methods include contacting an isomerization catalyst with an alcohol solution to create a reaction mixture, and maintaining the reaction mixture at a temperature of 25, 50, 75, or 100 °C to 125, 150, 200, or 250 °C for a time sufficient to remove a carbonaceous or sulfurous material from the isomerization catalyst forming a regenerated isomerization catalyst. In certain aspects the combination is incubated at temperature for 10, 20, 30, 40, 50, or 60 minutes or hours, including all values and ranges there between.

[0018] In some embodiments, the method of the disclosure includes combining an isomerization catalyst with an alcohol solution. As used herein, the term alcohol solution means a solution that comprises an alcohol, or a first alcohol, and optionally another component. In one embodiment, the alcohol solution includes an alcohol and an inorganic base, an alkali metal chloride, or mixtures thereof. Alcohols that may be used in accordance with the disclosure include, but are not limited to C2 to C4 alcohols. In one embodiment, the alcohol solution includes methanol, ethanol, or tert-butyl alcohol as a solvent.

[0019] Inorganic bases that may be used in accordance with the disclosure include, but are not limited to alkali metal hydroxides. In one embodiment, the alkali metal hydroxide is KOH or NaOH.

[0020] In one embodiment, the method includes combining an isomerization catalyst with an alkoxide solution to create a reaction mixture, and maintaining the reaction mixture at a temperature of 25, 50, 75, or 100 °C to 125, 150, 200, or 250 °C for a time sufficient to remove a carbonaceous or sulfurous material from the isomerization catalyst to form a regenerated isomerization catalyst. In certain aspects the reaction mixture is incubated at temperature for 10, 20, 30, 40, 50, or 60 minutes or hours, including all values and ranges there between.

[0021] In one embodiment, after creating a reaction mixture, the method includes combining the isomerization catalyst with a second alcohol at a temperature of 25, 50, 100, 150, 200, 250, or 300 °C to 350, 400, 450, 500, or 550 °C. Second alcohols that may be used in accordance with the disclosure include C2 to C4 alcohols. In certain aspects the reaction mixture is incubated at temperature for 10, 20, 30, 40, 50, or 60 minutes or hours, including all values and ranges there between.

[0022] In certain aspects the methods can include treating the isomerization catalyst with a chloro-organic compound at a temperature of 50, 100, 150, 200, 250, or 300 °C to 350, 400, 450, 500, or 550 °C. Chloro-organic compounds that may be used in accordance with the disclosure include, but are not limited to phosgene, chloro acetyl chloride, methylene chloride, dichloromethane, chloroform, carbon tetrachloride or mixtures thereof.

[0023] In some aspects the methods include combining an isomerization catalyst with an alkoxide solution. In one embodiment, the alkoxide solution comprises an alkoxide of formula R-O-X and an organic solvent, wherein R is an C2 to C4 alkane, O is oxygen, and X is an alkali earth metal. In certain aspect the alkali earth metal is sodium or potassium. Organic solvents that may be used in accordance with the disclosure include, but are not limited to C2 to C4 alcohols, benzene, C4 alcohols, carbon tetrachloride, chlorobenzene, 1,2- dichloroethane, diethyl ether, di ethylene glycol, 1,2-dimethoxy-ethane (DME), dimethylether, dimethyl-formamide (DMF), and dimethyl sulfoxide (DMSO).

[0024] The disclosure also relates to a process for converting n-butane to iso-butane, including combining n-butane with an isomerization catalyst treated in accordance with the disclosure.