Modified ultra-stable y (usy) zeolite catalysts for dealkylation of aromatic compounds

Abstract

The present disclosure relates to a process for hydrodealkylation of a hydrocarbon stream rich in aromatic compounds to produce benzene, toluene, and mixed xylenes (BTX) with high selectivity to high value xylenes. The process uses a catalyst containing a framework-substituted zirconium and / or titanium and / or hafnium modified ultra-stable Y (USY) type zeolite.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a process for hydrodealkylation of a hydrocarbon stream rich in aromatic compounds to produce benzene, toluene, and mixed xylenes (BTX) with high selectivity to valuable xylenes. The process uses a catalyst containing a framework-substituted zirconium and / or titanium and / or hafnium modified ultra-stable Y (USY) type zeolite. BACKGROUND

[0002] Catalytic reforming is a widely used process for refining hydrocarbon mixtures that produces reformate, a gasoline blending fraction rich in aromatic compounds that can be used for aromatic production. The reformate from the catalytic reforming unit is sent to an aromatic complex to recover high value products such as xylenes and benzene, and to convert lower value products such as toluene into higher value products. For example, toluene is typically recovered as a separate fraction and subjected to disproportionation to produce benzene and xylenes or is hydrodealkylated to produce benzene.

[0003] Aromatic complexes produce very heavy (boiling point in the range of 100-450 °C) waste streams or bottoms that contain C9+ alkylated aromatic compounds with alkyl groups containing 3 or more carbon numbers. The heavy bottoms fraction is not suitable as a gasoline blending component because it degrades gasoline quality and negatively impacts engine performance in the long run. In addition, blending is becoming more difficult due to more stringent regulations on aromatic content in gasoline.

[0004] Para-xylene is experiencing a growing rate of market demand. Therefore, converting heavy aromatic compounds to para-xylene provides a valuable product stream. Thus, it is desirable to utilize the heavy reformate fraction via dealkylation of alkylated aromatic compounds to obtain a BTX rich in xylenes. SUMMARY

[0005] A method and system for hydrodealkylation of heavy reformate rich in aromatic compounds using a catalyst containing a modified framework-substituted ultra-stable Y (USY) zeolite is disclosed.

[0006] The present disclosure relates to a system for hydrodealkylating a bottoms stream from an aromatics recovery complex to produce benzene, toluene, and xylenes (BTX) with selectivity to high value xylenes. The process utilizes a catalyst containing a modified framework-substituted ultra-stable Y (USY) zeolite in which titanium (Ti) and / or zirconium (Zr) and / or hafnium (Hf) is intercalated into the dealuminated zeolite catalyst. The use of the modified USY zeolite catalyst according to the present disclosure results in a higher ratio of xylenes to toluene and benzene compared to known processes. Thus, the process of the present disclosure provides the technical advantage of preferentially forming high value xylenes and reducing the formation of lower value benzene and toluene.

[0007] Thus, in some embodiments, the present disclosure provides a process for hydrodealkylating a hydrocarbon feed comprising aromatic hydrocarbons having 9 or more carbon atoms (C9+ aromatic compounds) by reacting the hydrocarbon feed with a hydrogen feed in the presence of a dealkylation catalyst, wherein the dealkylation catalyst is a framework-substituted ultra-stable Y (USY) type zeolite.

[0008] In other embodiments, the present disclosure provides a process for producing mixed xylenes from a hydrocarbon feed comprising aromatic hydrocarbons having C9+ aromatic compounds by reacting the hydrocarbon feed with a hydrogen feed in the presence of a dealkylation catalyst that hydrodealkylates the aromatic compounds in the hydrocarbon feed; wherein the dealkylation catalyst is a framework-substituted ultra-stable Y (USY) type zeolite.

[0009] In some embodiments, the framework-substituted USY zeolite is a zeolite in which a portion of the aluminum atoms that make up its zeolite framework are substituted with zirconium atoms and / or titanium and / or hafnium atoms. In other embodiments, the framework-substituted USY zeolite can be supported on a support containing an inorganic oxide such as alumina, silica-alumina, and the like, as described herein.

[0010] Preferably, the hydrocarbon feed comprises a heavy reformate feed (e.g., a bottoms stream) enriched in aromatic compounds comprising a hydrocarbon oil enriched in aromatic compounds having a boiling point range of about 50°C to about 500°C.

[0011] The process of the present disclosure results in the formation of a BTX fraction with strong selectivity to para-xylene. In some embodiments, the ratio of mixed xylenes to benzene and toluene is at least about 2 to 1, preferably at least about 3 to 1. In other embodiments, the ratio of benzene to toluene to xylenes is about 1 :4-10: 15-25.

[0012] Further embodiments and full scope of applicability of the present disclosure will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the application, are given by way of illustration only, since various changes and modifications within the spirit and scope of the application will become apparent to one of ordinary skill in the art from this detailed description. BRIEF DESCRIPTION OF DRAWINGS

[0013] A more complete understanding of the present application, and the attendant advantages and features thereof, will be more fully understood by reference to the following detailed description when considered in conjunction with the accompanying drawings wherein:

[0014] Figure 1 A schematic of an embodiment of the process is provided. DETAILED DESCRIPTION

[0015] While the scope of the apparatus and methods will be described in various embodiments, it is understood that those of ordinary skill in the relevant art will appreciate that many examples, variations and alterations to the apparatus and methods described herein are within the scope and spirit of the described embodiments.

[0016] Accordingly, the described embodiments are set forth without limitation to any generally described use or embodiment, and without limitation to the final forms thereof. Those skilled in the art understand and appreciate the scope of the present disclosure and realize additional ones can be made without departing from the scope of the present disclosure.

[0017] Described herein are processes and systems for producing mixed xylenes by hydrodealkylating a heavy hydrocarbon feed containing C9+aromatics, such as a heavy bottoms reformer feed. A heavy bottoms reformer feed and a hydrogen feed, such as hydrogen gas, are introduced to a dealkylation reactor containing a dealkylation catalyst. The dealkylation catalyst is a catalyst containing a framework-substituted ultra-stable Y (USY) type zeolite, wherein a portion of aluminum atoms constituting a zeolite framework thereof are substituted with zirconium atoms and / or titanium and / or hafnium atoms. Optionally, a dealkylation effluent from the dealkylation reactor is introduced to a separator unit to separate components of the dealkylation effluent.

[0018] Advantageously, the use of a catalyst containing a framework-substituted ultra-stable Y (USY) type zeolite increases the overall production of xylenes compared to other catalysts. Thus, the process results in the dealkylation of C9+aromatics to produce benzene, toluene, and mixed xylenes (BTX), preferably high value xylenes.

[0019] Definitions

[0020] As used throughout, reference to "C" and a number refers to the number of carbon atoms in a hydrocarbon. For example, C6 refers to a hydrocarbon having 6 carbon atoms, and C7 refers to a hydrocarbon having 7 carbon atoms, and the like.

[0021] As used throughout, "C8aromatics" refers to aromatic hydrocarbons having eight carbon atoms. Examples of C8aromatics include mixed xylenes and ethylbenzene. As used throughout, "mixed xylenes" refers to one or more of para-xylene (p-xylene), meta-xylene (m-xylene), and ortho-xylene (o-xylene).

[0022] As used throughout, "C9aromatics" refers to aromatic hydrocarbons having nine carbon atoms. Examples of C9aromatics include methyl ethyl benzene, trimethyl benzene, and propyl benzene.

[0023] As used throughout, "C10+ aromatics" refers to aromatic hydrocarbons having ten carbon atoms and aromatic compounds having more than 10 carbon atoms, for example, aromatic hydrocarbons having 11 carbon atoms. C10+ aromatics can include bicyclic aromatic compounds. Examples of bicyclic aromatic compounds of C10+ aromatics include naphthalene, methylnaphthalene, naphthalene derivatives, and combinations thereof. Examples of methylnaphthalene include 1-methylnaphthalene, 2-methylnaphthalene, and combinations thereof.

[0024] As used throughout, "C9aromatics" refers to a group of C9aromatics and C10+ aromatics.

[0025] As used herein, the term "BTX" means a composition comprising benzene (C6), toluene (C7), and mixed xylenes (C8). As used herein, the term "xylene" means any one of ortho-xylene (o-xylene), meta-xylene (m-xylene), para-xylene (p-xylene), or any combination thereof. As used throughout, "mixed xylenes" refers to any one or more of o-xylene, m-xylene, and p-xylene.

[0026] As used throughout, "dealkylation reaction" refers to a reaction that results in the removal of one or more alkyl groups from one or more reactants.

[0027] As used throughout, "light hydrocarbons" refers to one or more alkanes, including methane, ethane, propane, butane, pentane, alkenes, and trace amounts of cycloalkanes, such as cyclopentane, cyclohexane.

[0028] As used throughout, "light gas" refers to one or more of light hydrocarbons, hydrogen, and air.

[0029] As used throughout, "monocyclic aromatic compounds" refers to aromatic compounds containing at least 6 carbon atoms arranged in a central aromatic ring, and includes rings having hydrogen and hydrocarbons as substituents.

[0030] Description of the embodiments

[0031] Reference Figure 1 Embodiments of a process for producing mixed xylenes are provided. A heavy reformate feed 100 is introduced to a dealkylation reactor 10 along with a hydrogen feed 105. The heavy reformate feed 100 can include toluene, mixed xylenes, C9 aromatics, and C10+ aromatics, as described below.

[0032] The hydrogen feed 105 can be any stream containing hydrogen gas. The hydrogen feed 105 can be a pure hydrogen stream from a fresh hydrogen source. In at least one embodiment, the hydrogen feed 105 can be from a hydrogen source in a refinery and can contain light hydrocarbons.

[0033] The dealkylation reactor 10 can be any type of reactor capable of containing and supporting a dealkylation reaction. The dealkylation reactor 10 can be a fixed bed reactor or a fluidized bed reactor. The dealkylation temperature in the dealkylation reactor 10 can be between 400 degrees Celsius (°C) and 500 °C. The dealkylation pressure in the dealkylation reactor 10 can be between 20 bar (2,000 kiloPascals (kPa)) and 50 bar (5,000 kPa). The liquid hourly space velocity (LHSV) can be between about 0.5 per hour (hr -1 ) and about 5 hr -1 ). The hydrogen to hydrocarbon ratio can be about 100 to about 500 SLt / Lt (SLt / Lt).

[0034] The dealkylation reactor 10 includes a dealkylation catalyst containing a framework-substituted USY zeolite, which is a zeolite in which a portion of the aluminum atoms that make up its zeolite framework are substituted with zirconium atoms and / or titanium atoms and / or hafnium atoms, as further described below. The dealkylation catalyst can be selected to selectively convert one or more C9+ aromatics in a dealkylation reaction. The dealkylation reaction can convert the C9+ aromatics into toluene, benzene, mixed xylenes, and light gases. The reaction in the dealkylation reactor 10 can remove methyl, ethyl, propyl, butyl, and pentyl groups, and their isomers, attached to the C9+ aromatics.

[0035] In at least one embodiment, the dealkylation catalyst can be selected to convert greater than 97.5 weight percent of methylethylbenzenes to toluene. In at least one embodiment, the total conversion of C9+ aromatics can be greater than 98 weight percent due to the conversion of C9 aromatics and the removal of methyl, ethyl, propyl, butyl, and pentyl groups attached to C10+ aromatics.

[0036] The dealkylation reaction produces a dealkylated effluent 110, which can contain mixed xylenes, toluene, benzene, light gases, and C9+aromatics. The dealkylated effluent is then optionally introduced to a separator unit 20, which operates to separate and recover different fractions. The separator unit 20 can be any type of separation unit capable of separating a stream into its constituent parts. In at least one embodiment, the separator unit 20 can be a separator column(s) designed to separate a feed stream into multiple sub-streams. In at least one embodiment, the separator unit 20 can be multiple separator columns in series designed to separate one component from a feed stream. In at least one embodiment, the separator unit 20 can be one or more distillation units. In at least one embodiment, the separator unit 20 includes a distillation column operating at a pressure between 4 barg and 6 barg and a temperature between 20°C and 100°C to separate light gases from the first column feed to produce a light gas stream 120 and a liquid reaction effluent 122 containing C6+hydrocarbons.

[0037] In at least one embodiment, the separator unit 20 separates components to produce a light gas stream 120 and a liquid reaction effluent 122 containing a BTX (C6-8aromatics) and C9+aromatics stream. In at least one embodiment, the effluent 122 can be introduced to an aromatic recovery complex (ARC) 30, where such effluent is further processed to recover a BTX stream 124.

[0038] It will be appreciated by those skilled in the art that the separator unit 20 can be designed to operate at certain temperatures and pressures to produce the desired streams. In at least one embodiment, where the separator unit 20 is a distillation column, the distillation column can include multiple sections in one vessel, where each section has operating conditions corresponding to each individual column described in this section.

[0039] It will be clear to those skilled in the art that the apparatus for the hydrodealkylation process in the present disclosure is not particularly limited to the foregoing embodiments and any other apparatus can be used as long as the foregoing reactions are carried out. Various types of apparatus can be used. According to some embodiments, the process of the present disclosure can be carried out on a ebullated bed or slurry bed or moving bed reactor or CSTR or batch type reactor, etc.

[0040] Hydrocarbon feed

[0041] The hydrocarbon feed 100 used in the processes of the present disclosure can be any hydrocarbon feed that is rich in aromatic hydrocarbons. In preferred embodiments, the hydrocarbon feed is a heavy reformate feed produced from an aromatics recovery process (also referred to herein as an "aromatics bottoms fraction"). The heavy reformate feed is preferably rich in aromatic hydrocarbons, and can include toluene, mixed xylenes, C9aromatics, and C10+aromatics.

[0042] In at least one embodiment, the heavy reformate feed 100 can contain between 0 wt% and 10 wt% C6aromatics (benzene). In at least one embodiment, the heavy reformate feed 100 can contain between 0 wt% and 10 wt% C7aromatics (toluene). In at least one embodiment, the heavy reformate feed 100 can contain between 0 wt% and 10 wt% mixed xylenes. In at least one embodiment, the heavy reformate feed 100 can contain between 0 wt% and 10 wt% C6-C8aromatics. In at least one embodiment, the heavy reformate feed 100 can contain between 0 wt% and 10 wt% mixed xylenes and between 60 wt% and 100 wt% C9+aromatics. In at least one embodiment, the heavy reformate feed 100 can contain between 0 wt% and 40 wt% C6-C8aromatics and between 60 wt% and 100 wt% C9+aromatics. In at least one embodiment, the heavy reformate feed 100 can contain between 0 wt% and 10 wt% mixed xylenes, between 0 wt% and 10 wt% toluene, and between 80 wt% and 100 wt% C9+aromatics. In at least one embodiment, the heavy reformate feed 100 contains between 60 wt% and 100 wt% C9+aromatics. In at least one embodiment, the heavy reformate feed 100 contains between 60 wt% and 100 wt% C10+aromatics. In at least one embodiment, the heavy reformate feed 100 contains between 90 wt% and 100 wt% C10+aromatics. In at least one embodiment, the heavy reformate feed 100 contains between 60 wt% and 100 wt% C11+aromatics. In at least one embodiment, the heavy reformate feed 100 contains between 90 wt% and 100 wt% C11+aromatics.

[0043] In at least one embodiment, the heavy reformate feed 100 can include trace amounts of C8+ naphthenes and C10+ naphthalenes, including alkyl derivatives thereof. In further embodiments, the heavy reformate feed includes trace amounts of non-aromatic hydrocarbons. In at least one embodiment, the heavy reformate feed 100 contains between 0 wt% and 1 wt% C4-C12 n-paraffins. In at least one embodiment, the heavy reformate feed 100 contains between 0 wt% and 1 wt% C4-C12 i-paraffins. In at least one embodiment, the heavy reformate feed 100 contains between 0 wt% and 1 wt% C8+ naphthenes and C10+ naphthalenes.

[0044] In some embodiments, the heavy reformate feed includes an aromatic-rich hydrocarbon oil having a boiling point range of about 50°C to about 500°C. In other embodiments, the hydrocarbon feed includes an aromatic-rich hydrocarbon oil having a boiling point range of about 100°C to about 500°C. In other embodiments, the heavy reformate feed includes an aromatic-rich hydrocarbon oil having a boiling point range of about 150°C to about 500°C. In other embodiments, the heavy reformate feed includes an aromatic-rich hydrocarbon oil having a boiling point range of about 150°C to about 400°C.

[0045] The reformate feed often contains very small amounts of sulfur because they are typically subjected to desulfurization prior to reforming, such that the resulting gasoline product contains an acceptable level of sulfur that meets current sulfur specifications. In some embodiments, the dealkylated hydrocarbon product preferably contains less than about 500 ppm, preferably less than about 10 ppm, most preferably less than about 0.5 ppm of sulfur. In other embodiments, the dealkylated hydrocarbon product contains less than about 100 ppm, preferably less than about 10 ppm, most preferably less than about 0.5 ppm of nitrogen.

[0046] Dealkylated product

[0047] As a result of the dealkylation reaction, the amount of alkylated aromatic compounds is reduced relative to the amount of alkylated aromatic compounds in the initial feed. According to at least one embodiment, the hydrocarbon feed is dealkylated by at least about 50%. According to at least one embodiment, the hydrocarbon feed is dealkylated by at least about 60%. According to at least one embodiment, the hydrocarbon feed is dealkylated by at least about 70%.

[0048] Advantageously, the process of the present disclosure produces a dealkylated product including benzene, toluene, mixed xylenes (BTX), C9 aromatic compounds, and C10+ aromatic compounds. Optionally, the dealkylated product contains trace amounts of C8+ naphthenes, C10+ naphthalenes, C4-C12 n-paraffins, and / or C4-C12 i-paraffins.

[0049] Advantageously, the process of the present disclosure is characterized by producing a BTX fraction that is strongly selective for xylene over benzene and toluene. Thus, in at least one embodiment, the process produces a higher amount of mixed xylenes compared to benzene and toluene. In at least one embodiment, the ratio of mixed xylenes to benzene and toluene is at least about 2 to 1. In at least one embodiment, the ratio of mixed xylenes to benzene and toluene is preferably at least about 3 to 1.

[0050] In other embodiments, the ratio of benzene to toluene to xylene is about 1 :4-10: 15-25 (expressed as benzene:toluene:xylene, and normalized to benzene). In other embodiments, the ratio of benzene to toluene to xylene is about 1 :4-7: 18-25.

[0051] Catalyst with framework-substituted ultra-stable Y (USY) zeolite

[0052] The dealkylation reactor 10 can include a dealkylation catalyst. Advantageously, the dealkylation catalyst contains a framework-substituted zeolite, wherein a portion of aluminum atoms that make up the zeolite framework are substituted with zirconium atoms and / or titanium atoms and / or hafnium atoms.

[0053] In some embodiments, the catalyst having a framework-substituted zeolite catalyst used in the process of the present disclosure is a Y-type zeolite, wherein silicon atoms and aluminum atoms form the zeolite framework, and wherein a portion of the aluminum atoms are substituted with zirconium atoms and / or titanium atoms and / or hafnium atoms. For example, a framework-substituted zeolite in a catalyst wherein a portion of the aluminum atoms that form the zeolite framework are substituted with zirconium atoms only is referred to as a “zirconium-substituted zeolite” or “Zr-USY”; a framework-substituted zeolite in a catalyst wherein a portion of the aluminum atoms that form the zeolite framework of the framework-substituted zeolite are substituted with titanium atoms only is referred to as a “titanium-substituted zeolite” or “Ti-USY”; a framework-substituted zeolite in a catalyst wherein a portion of the aluminum atoms that form the zeolite framework are substituted with zirconium atoms and titanium atoms only is referred to as a “zirconium-titanium-substituted zeolite” or “Zr-Ti-USY”; and a framework-substituted zeolite in a catalyst wherein a portion of the aluminum atoms that form the zeolite framework are substituted with zirconium atoms, titanium, and hafnium atoms is referred to as a “zirconium-titanium-hafnium-substituted zeolite” or “Zr-Ti-Hf-USY”.

[0054] The zirconium atoms and / or titanium and / or hafnium atoms that substitute the aluminum atoms that form the framework of the Y-type zeolite serve as components of the framework of the Y-type zeolite. The substitution can be verified by, for example, ultraviolet, visible, and near-infrared spectrophotometry (UV-Vis-NIR), Fourier-transform infrared spectroscopy (FT-IR).

[0055] In some embodiments, in addition to the substituted atoms, the zirconium atoms and / or titanium and / or hafnium atoms can be further attached (supported) to the outside of the framework of the USY-type catalyst or combined with the framework of the USY-type catalyst, as described in U.S. Patent No. 10,293,332, which is incorporated herein by reference in its entirety as if fully set forth herein.

[0056] In some embodiments, the framework-substituted zeolite of the catalyst contains about 0.1 mass% to about 5 mass%, preferably about 0.2 mass% to about 4 mass%, more preferably about 0.3 mass% to about 3 mass% of zirconium atoms and / or titanium and / or hafnium atoms, based on the framework-substituted zeolite, as oxide (i.e., “ZrO2”, “TiO2”, and “HfO2”). As contemplated herein, the content range of the zirconium atoms and / or titanium and / or hafnium atoms, based on oxide, includes all contents of the zirconium atoms and / or titanium and / or hafnium atoms that substitute for aluminum atoms forming the framework of the zeolite as well as the zirconium atoms and / or titanium and / or hafnium atoms that do not substitute for the aforementioned aluminum atoms.

[0057] As understood by one skilled in the art, when the framework-substituted zeolite in the catalyst contains the aforementioned zirconium atoms and titanium atoms and / or hafnium atoms, the mass ratio of the zirconium atoms to the titanium atoms and / or hafnium atoms (as oxide) is not particularly limited, and any ratio of zirconium or titanium or hafnium effective to carry out the process of the present application can be used.

[0058] The content of the zirconium atoms and / or titanium and / or hafnium atoms of the framework-substituted zeolite in the catalyst can be measured, for example, with an X-ray fluorescence analyzer, a high-frequency plasma emission spectrometer, an atomic absorption spectrometer, or the like.

[0059] In some embodiments, the particles of the zirconium and / or titanium and / or hafnium-modified USY catalyst have a diameter of 50 nm or less.

[0060] Process for preparing framework-substituted zeolite

[0061] The framework-substituted zeolite in the catalyst in the present application can be produced according to the method described in U.S. 10,293,332. For example, the framework-substituted zeolite in the catalyst can be produced by calcining a USY-type zeolite (having a lattice constant of 2.430 to 2.450 nm, a specific surface area of 600 to 900 m 2 / g, and a molar ratio of SiO2 to Al2O3 of 20 to 100), forming a suspension containing the calcined USY-type zeolite (having a liquid / solid mass ratio of 5 to 15), adding an inorganic acid or an organic acid such that the pH of the aforementioned suspension is 1.0 to 2.0, subsequently adding a solution containing a zirconium compound and / or a hafnium compound and mixing them, and neutralizing the solution with, for example, aqueous ammonia in such a way that the mixed solution has a pH of about 7.

[0062] Ultra-stable Y-type zeolite is used as one of the raw materials for preparing a framework-substituted zeolite in a catalyst. The ultra-stable Y-type zeolite means a zeolite having a lattice constant (UD) falling within a range of 2.430 nm or more and 2.450 nm or less, a specific surface area of 600 to 900 m 2 / g and a molar ratio of SiO2 to Al2O3 (silica-alumina ratio) falling within a range of 20 to 100. The ultra-stable Y-type zeolite can be prepared by any method known in the art.

[0063] In the method for preparing a framework-substituted ultra-stable Y-type zeolite, aluminum outside the framework (aluminum atoms not forming a zeolite framework) can be removed from the ultra-stable Y-type zeolite raw material to obtain the ultra-stable Y-type zeolite. The aluminum outside the framework can be removed by, for example, dispersing the ultra-stable Y-type zeolite in warm water at 40 to 95°C to prepare a suspension, adding sulfuric acid to the above suspension and stirring it for 10 minutes to 3 hours while maintaining the temperature at 40 to 95°C, thereby dissolving the aluminum outside the framework. After dissolving the aluminum outside the framework, the suspension is filtered, and the residue on the filter is washed with purified water at 40 to 95°C, and dried at 100 to 180°C for 3 to 30 hours, whereby the ultra-stable Y-type zeolite from which the aluminum outside the framework is removed can be obtained.

[0064] Further, in the method for producing a framework-substituted ultra-stable Y-type zeolite, the ultra-stable Y-type zeolite raw material can be calcined at 500°C to 700°C, preferably 550°C to 650°C. The calcination time should not be particularly limited as long as the target framework-substituted zeolite is obtained, and the calcination can be performed, for example, in a range of 30 minutes to 10 hours. As for the calcination atmosphere of the ultra-stable Y-type zeolite, it is preferable to be performed in air. The calcined ultra-stable Y-type zeolite is suspended in water at a temperature of about 20°C to about 30°C to form a suspension. As for the concentration of the ultra-stable Y-type zeolite suspension, it is preferable that the liquid / solid mass ratio is in a range of 5 to 15, and more preferably, a mass ratio of 8 to 12 is recommended.

[0065] Next, an inorganic acid or an organic acid is added thereto so that the pH of the above suspension is controlled to 1.0 to 2.0, and then a solution containing a zirconium compound and / or a hafnium compound is added and mixed. Then, the mixed solution is neutralized (pH 7.0 to 7.5), and desirably dried at 80 to 180°C, whereby the above framework-substituted zeolite can be obtained.

[0066] Sulfuric acid, nitric acid, hydrochloric acid, and the like can be given as the inorganic acid used above, and among them, sulfuric acid, hydrochloric acid, and the like are particularly preferred. Further, a carboxylic acid can be suitably used as the above-mentioned organic acid. The amount of the inorganic acid or the organic acid should not be limited as long as the pH of the suspension can be controlled to the range of 1.0 to 2.0, and is, for example, 0.5 to 4.0 times the molar amount and preferably 0.7 to 3.5 times the molar amount based on the amount of AI2O3 in the ultrastable Y-type zeolite, but should not be limited to the above range.

[0067] Examples of the above-mentioned zirconium compound include zirconium sulfate, zirconium nitrate, zirconium chloride, and the like. Among these compounds, zirconium sulfate, zirconium nitrate, and the like are particularly preferred. The amount of the zirconium compound added with respect to the above-mentioned ultrastable Y-type zeolite is preferably about 0.1 mass% to about 5 mass% and more preferably about 0.2 mass% to about 4 mass% based on zirconium oxide. Generally, an aqueous solution of the zirconium compound prepared by dissolving the zirconium compound in water is suitably used as the zirconium compound.

[0068] Examples of the above-mentioned hafnium compound include hafnium chloride, hafnium nitrate, hafnium fluoride, hafnium bromide, hafnium oxalate, and the like. Among these compounds, hafnium chloride, hafnium nitrate, and the like are particularly preferred. The amount of the hafnium compound added with respect to the ultrastable Y-type zeolite is preferably about 0.1 mass% to about 5 mass% and more preferably about 0.2 mass% to about 4 mass% based on hafnium oxide. Generally, an aqueous solution of the hafnium compound prepared by dissolving the hafnium compound in water is suitably used as the hafnium compound.

[0069] In some embodiments, a titanium compound can be added to the above-mentioned mixed solution. Examples of the titanium compound include titanium sulfate, titanium acetate, titanium chloride, titanium nitrate, and titanium lactate. Among these compounds, titanium sulfate, titanium acetate, and the like are particularly preferred. The amount of the titanium compound added with respect to the ultrastable Y-type zeolite is preferably about 0.1 mass% to about 5 mass% and more preferably about 0.2 mass% to about 4 mass% based on the oxide. Generally, an aqueous solution of the titanium compound prepared by dissolving the titanium compound in water is suitably used as the titanium compound.

[0070] In order to prevent the generation of a precipitate at the time of mixing the aqueous solution of the zirconium compound, the hafnium compound, or the titanium compound with the suspension of the ultrastable Y-type zeolite described above, it is necessary to control the pH of the above-mentioned suspension in advance to the range of 1.0 to 2.0.

[0071] In the case where the aqueous solution of the zirconium compound, hafnium compound or titanium compound is mixed with the suspension of the ultrastable Y-type zeolite, the above aqueous solution is preferably gradually added to the suspension. After the addition of the above-described aqueous solution to the suspension is completed, the solution is preferably mixed by stirring at, for example, room temperature (about 25°C to about 35°C) for 3 to 5 hours. Further, after the above-described mixing is completed, the mixed solution described above is neutralized by adding a base such as aqueous ammonia or the like so that its pH is controlled to 7.0 to 7.5, whereby the framework-substituted zeolite in the catalyst can be obtained.

[0072] It is clear to those skilled in the art that, when only a zirconium compound (or an aqueous solution thereof) is used as the compound (or an aqueous solution thereof) added to the above-described suspension, a framework-substituted zeolite in a catalyst (Zr-USY) in which zirconium atoms substitute for a part of aluminum atoms forming the framework of the ultrastable Y-type zeolite is formed; when only a hafnium compound (or an aqueous solution thereof) is used, a framework-substituted zeolite in a catalyst (Hf-USY) in which hafnium atoms substitute for a part of aluminum atoms forming the framework of the ultrastable Y-type zeolite is formed; when only a titanium compound (or an aqueous solution thereof) is used, a framework-substituted zeolite in a catalyst (Ti-USY) in which titanium atoms substitute for a part of aluminum atoms forming the framework of the ultrastable Y-type zeolite is formed; when a zirconium compound and a titanium compound (or an aqueous solution thereof) are used, a framework-substituted zeolite in a catalyst (Zr-Ti-USY) in which zirconium atoms and titanium atoms substitute for a part of aluminum atoms forming the framework of the ultrastable Y-type zeolite is formed; when a zirconium compound and a hafnium compound (or an aqueous solution thereof) are used, a framework-substituted zeolite in a catalyst (Zr-Hf-USY) in which zirconium atoms and hafnium atoms substitute for a part of aluminum atoms forming the framework of the ultrastable Y-type zeolite is formed; and when a zirconium compound, a titanium compound and a hafnium compound (or an aqueous solution thereof) are used, a framework-substituted zeolite in a catalyst (Zr-Ti-Hf-USY) in which zirconium atoms, titanium atoms and hafnium atoms substitute for a part of aluminum atoms forming the framework of the ultrastable Y-type zeolite is formed.

[0073] If necessary, the resulting framework-substituted zeolite in the catalyst is preferably filtered, washed with water, and dried at about 80°C to about 180°C.

[0074] The framework-substituted USY zeolite can be supported on a carrier containing an inorganic oxide in addition to the framework-substituted zeolite in the catalyst described above, excluding the framework-substituted zeolite in the above-described catalyst. The inorganic oxide typically contains a substance used as a granulating agent or a binder. Generally, known substances contained in a carrier including a Y-type zeolite and used as a granulating agent or the like can be used. Examples of the inorganic oxide include, but are not limited to, alumina, silica, titania, silica-alumina, alumina-titania, alumina-zirconia, alumina-boria, phospho-alumina, silica-alumina-boria, phospho-alumina-boria, phospho-alumina-silica, silica-alumina-titania, and silica-alumina-zirconia. In the present disclosure, in particular, an inorganic oxide consisting mainly of alumina, silica-alumina is preferred.

[0075] The content of the framework-substituted zeolite in the catalyst and the inorganic oxide content of the carrier can be appropriately determined according to the purpose. The carrier includes about 2 mass% to about 80 mass%, preferably about 10 mass% to about 80 mass%, and more preferably about 20 mass% to about 70 mass% of the framework-substituted zeolite in the catalyst, and about 98 mass% to about 20 mass%, preferably about 90 mass% to about 20 mass%, and more preferably about 80 mass% to about 30 mass% of the inorganic oxide content.

[0076] Metal components:

[0077] The catalyst used in the process of the present disclosure can further include an active metal component selected from the group consisting of IUPAC Groups 6 to 11 metals of the periodic table. Examples of the active metal include iron, cobalt, nickel, rhodium, palladium, silver, iridium, platinum, or gold in the long periodic table Group 8, and / or the metal component chromium, molybdenum, or tungsten in Group 6. Preferred examples of the metal component include a combination of molybdenum or tungsten in Group 6 and cobalt or nickel in Group 8; and a platinum group metal component (platinum, rhodium, palladium, etc.).

[0078] When present, the metal component can be contained in the catalyst in an amount of about 0.0001 to about 40 mass% as an oxide. In the case of molybdenum, tungsten, cobalt, or nickel, the amount is particularly preferably about 3 to about 30 mass% as an oxide, based on the mass of the catalyst. In the case of the platinum group (platinum, rhodium, palladium, etc.), when present, the amount is particularly preferably about 0.01 to about 2 mass% as a metal.

[0079] Examples

[0080] The following examples are provided to better illustrate embodiments of the present disclosure. However, it is understood that these examples are merely illustrative in nature and that the process embodiments of the present disclosure are not necessarily limited thereto.

[0081] Example 1:

[0082] Example 1 provides a reference Figure 1 Analysis of dealkylation reactor 10. The heavy reformate feed 100 had the composition of Table 1. The feed composition and properties are summarized in Table 1. The detailed composition obtained from PIONA analysis is shown in Table 2.

[0083] Table 1. Feed properties.

[0084] Property (unit) Unit Value Density @ 15 °C Kg / L 0.84 Carbon wt% (W%) 89.85 Hydrogen wt% 10.15 Sulfur wt% 1.42 Nitrogen ppmw 73 Distillation (D2887) IBP ℃ 91 10 wt% ℃ 187 30 wt% ℃ 253 50 wt% ℃ 293 70 wt% ℃ 331 90 wt% ℃ 381 FBP ℃ 441

[0085] Table 2. Feed compound-type composition (wt%)

[0086] Carbon number 4 5 6 7 8 9 10 11 12+ Total n-paraffins 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 i-paraffins 0.00 0.00 0.00 0.00 0.00 0.00 0.03 0.04 0.30 0.37 naphthenes 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.07 0.07 aromatics 0.00 0.00 0.00 0.06 1.04 84.20 11.08 3.18 0.00 99.56 Total 0.00 0.00 0.00 0.06 1.04 84.20 11.11 3.22 0.37 100.00

[0087] The pilot plant test conditions are summarized in Table 3.

[0088] Table 3 - Operating conditions

[0089] Variable Unit Value Catalyst Ni-Mo / Ti-Zr-modified USY zeolite Temperature ℃ 400、425 LHSV h -1 ]]> 1.0 H2 / Oil ratio SLt / L 200、400t Hydrogen partial pressure Bar 30s

[0090] The catalyst was a framework-substituted ultra-stable Y (USY) type zeolite in which a portion of the aluminum atoms constituting the zeolite framework thereof were substituted with zirconium atoms and titanium atoms, which further included nickel (Ni) and molybdenum (Mo) as active metals.

[0091] Result:

[0092] The aromatic compound dealkylation results are shown in Table 4 (reaction temperature: 400°C) and Table 5 (reaction temperature: 425°C):

[0093] Table 4: Dealkylation results at 400°C

[0094]

[0095] Table 5: Dealkylation results at 425°C

[0096]

[0097] The benzene / toluene / xylene ratios obtained from the experiments in Table 4 are summarized in Table 6.

[0098] Table 6.

[0099]

[0100] The benzene / toluene / xylene ratios obtained from the experiments in Table 5 are summarized in Table 7.

[0101] Table 7.

[0102]

[0103] Comparative example:

[0104] Table 8 provides the benzene / toluene / xylene ratios obtained according to the process of US 2019 / 0194095 Example 1. The process of US 2019 / 0194095 used a ZSM-5 zeolite catalyst at 400 °C. US 2019 / 0194095 is expressly incorporated by reference in its entirety.

[0105] Table 8:

[0106]

[0107] As seen, the process of the present disclosure produces products with a benzene:toluene:xylene ratio of 1.0:6.7:19.5 at 400 °C and a benzene:toluene:xylene ratio of 1.0:5.0:21.8 at 425 °C, while the process of US 2019 / 0194095 leads to a benzene:toluene:xylene ratio of 1:0:6.5:6.6 at 400 °C.

[0108] Thus, the ratio / selectivity of toluene and xylene is similar according to the process of US 2019 / 0194095 using a ZSM-5 catalyst. However, in the process of the present disclosure using a framework-substituted ultra-stable Y (USY) type zeolite, there is a strong selectivity for xylene over benzene and toluene. Thus, the use of the modified USY zeolite catalyst according to the present disclosure provides a technical advantage as it leads to a higher proportion of the desired high-value xylene compared to toluene and benzene.

[0109] The foregoing description of specific implementations will so fully reveal the general nature of the application that others can adapt and / or merely apply such descnptions to various applications and / or purposes without undue experimentation. Consequently, while the specific implementations have been described in terms of preferred embodiments and optional features, it is to be understood that the application should not be limited to such disclosure but is understood to encompass any and all embodiments within the broad concepts, the great framework, and the narrow framework thereof. Therefore, the foregoing description is not intended to be exhaustive or to limit the application to the precise forms disclosed. Modifications or variations are possible in light of the above teachings. The implementation(s) disclosed is / are provided for the best modes contemplated for carrying out the application. Of course, to be consistent with the statute, implementations falling under 35 U.S.C. 112(f) are specifically intended to be disclosd in this patent specification.

Claims

1. A process for hydrodealkylating a hydrocarbon feed to produce a dealkylated product, the process comprising reacting the hydrocarbon feed with a hydrogen feed in the presence of a dealkylation catalyst, wherein the hydrocarbon feed comprises aromatic hydrocarbons having 9 or more carbon atoms, i.e., C9+ aromatic compounds; and wherein the dealkylation catalyst is a framework-substituted ultrastable Y (USY) type zeolite, in which a portion of the aluminum atoms constituting the zeolite framework thereof are substituted with zirconium atoms and / or titanium atoms and / or hafnium atoms.

2. The process according to claim 1, further comprising the steps of: introducing the hydrocarbon feed and the hydrogen feed to a dealkylation reactor, wherein the dealkylation reactor contains the dealkylation catalyst; and The hydrocarbon feed is reacted with the hydrogen feed in the presence of the dealkylation catalyst to produce a dealkylation product.

3. The process according to claim 1 or 2, wherein the framework-substituted USY-type zeolite in the catalyst comprises zirconium atoms and titanium atoms.

4. The process according to claim 1 or 2, wherein the framework-substituted USY-type zeolite in the catalyst contains 0.1 to 5 mass % of zirconium and / or titanium and / or hafnium atoms, each calculated on an oxide basis.

5. The process according to claim 1 or 2, wherein the framework-substituted USY-type zeolite in the catalyst is supported on a carrier comprising an inorganic oxide selected from the group consisting of alumina, silica-alumina and combinations thereof.

6. The process according to claim 1 or 2, wherein the framework-substituted USY-type zeolite in the catalyst further comprises alumina as a binder.

7. The process according to claim 1 or 2, wherein the catalyst further comprises an active metal selected from the group consisting of IUPAC Groups 6 to 11 of the Periodic Table.

8. The process of claim 1 or 2, wherein the dealkylated product comprises BTX and C9+ aromatic compounds, wherein BTX means a composition comprising benzene, toluene and mixed xylenes.

9. The process of claim 8, wherein the mixed xylenes are produced in higher amounts compared to benzene and toluene.

10. The process of claim 9, wherein the weight ratio of mixed xylenes to benzene and toluene is at least 2 to 1, expressed as a weight ratio of mixed xylenes:benzene+toluene.

11. A process according to claim 10, wherein the weight ratio of mixed xylenes to benzene and toluene is at least 3 to 1, expressed as a weight ratio of mixed xylenes:benzene+toluene.

12. The process according to claim 9, wherein the weight ratio of benzene to toluene to xylene in the dealkylated product is 1:4-10:15-25.

13. The process of claim 1 or 2, wherein the hydrocarbon feed comprises an aromatics-rich hydrocarbon oil having a boiling point range of 50°C to 500°C.

14. The process of claim 1 or 2, wherein the hydrocarbon feed comprises a heavy reformate feed rich in aromatics.

15. The process according to claim 1 or 2, wherein the reaction temperature is in the range of 400°C to 500°C, the pressure is in the range of 20 to 50 bar, and the reaction time is in the range of 0.5 to 5 hours. -1 The reactor is operated at an LHSV of 100 to 500 SLt / Lt and a hydrogen to hydrocarbon ratio of 100 to 500 SLt / Lt.

16. The process of claim 1 or 2, which operates at a reaction temperature range of 400°C to 425°C.

17. The process of claim 1 or 2, wherein the hydrogen feed comprises hydrogen gas.

18. The process of claim 1 or 2, wherein the dealkylated product contains less than 500 ppm by weight of sulfur.

19. The process of claim 1 or 2, wherein the dealkylated product contains less than 10 ppm by weight of sulfur.

20. The process of claim 1 or 2, wherein the dealkylated product contains less than 0.5 ppm by weight of sulfur.

21. The process of claim 1 or 2, wherein the dealkylated product contains less than 100 ppm by weight of nitrogen.

22. The process of claim 1 or 2, wherein the dealkylated product contains less than 10 ppm by weight of nitrogen.

23. The process of claim 1 or 2, wherein the dealkylated product contains less than 0.5 ppm by weight of nitrogen.

24. The process of claim 1 or 2, wherein the hydrocarbon feed is dealkylated by at least 50% by weight.

25. The process of claim 1 or 2, wherein the hydrocarbon feed is dealkylated by at least 60% by weight.

26. The process of claim 1 or 2, wherein the hydrocarbon feed is dealkylated by at least 70% by weight.

27. The process of claim 1 or 2, further comprising the step of introducing the dealkylated product into a separator unit and separating the dealkylated product into a light hydrocarbon stream and a stream comprising C6+ aromatics.

28. The process of claim 27, wherein the stream comprising C6+ aromatics comprises BTX and C9+ aromatics, wherein BTX means a composition comprising benzene, toluene, and mixed xylenes.

29. The process of claim 28, further comprising the step of introducing the stream comprising C6+ aromatics into an aromatics recovery complex to recover BTX.

30. A process for producing mixed xylenes from a hydrocarbon feed, the process comprising the steps of reacting the hydrocarbon feed with a hydrogen feed in the presence of a dealkylation catalyst, the dealkylation catalyst hydrodealkylating aromatic hydrocarbons in the hydrocarbon feed; wherein the hydrocarbon feed comprises aromatic hydrocarbons having 9 or more carbon atoms, i.e., C9+ aromatic compounds; and wherein the dealkylation catalyst is a framework-substituted ultrastable Y (USY) type zeolite, wherein a portion of the aluminum atoms constituting the zeolite framework thereof are substituted with zirconium atoms and / or titanium and / or hafnium atoms.

31. The process of claim 30, wherein the hydrocarbon feed is a heavy reformate feed.

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