[0001] This application claims the benefit of priority of U.S. Provisional Patent Application No. 62/361,616 filed July 13, 2016, which is hereby incorporated by reference in its entirety.

BACKGROUND OF THE INVENTION

A. Field of the Invention

[0002] The invention generally concerns multi -layered or core/shell structured zeolites that include two different zeolites having different silica (Si0 ₂ ) to alumina (A1 ₂ 0 ₃ ) ratios (SARs). A first zeolite is in direct contact with the second zeolite defining an interface between the first and second zeolites. The silicon (Si) and optional aluminum (Al), if present, in the second zeolite is from the first zeolite.

B. Description of Related Art

[0003] Zeolites belong to a broader material category known as "molecular sieves." Zeolites can have uniform, molecular-sized pores, and can be separated based on their size, shape, and polarity. For example, zeolites can have pore sizes ranging from about 0.3 nm to about 1 nm. Currently, more than 200 different zeolite types are registered and referenced by the International Zeolite Association (IZA). Zeolites can exhibit a regular microporosity with interconnection of some cages, in the scale of few Angstroms, which can allow specific chemical reactions to occur. Due to their very specific porosity and their high surface area, zeolites can be used both as a support and a catalyst. In some cases, a zeolite can include metallic compounds to enhance the reactivity of a specific chemical reaction. Various attempts have been tried to control the metallic particle dispersion on the surface of the zeolite. However, because the metallic particles are in the same scale as the pore of the zeolite, the metallic particles can diffuse through the pore. This can result in deactivation of the catalyst and/or leaching of the metallic particle from the catalyst.

[0004] Other attempts to control leaching of the metallic particle include making double- layered zeolites using bonding material. By way of example, Lauridant et al. {Microporous and Mesoporous Materials, 2013, 166:79-85) describes adding a cationic polymer on the surface of a first zeolite and then crystallizing a second zeolite on the surface of the cationic polymer. This double-layered zeolite suffers in that nonhomogeneous and/or incomplete coverage of the cationic polymer by the second zeolite occurs. In another example, U.S. Patent No. 6,710,003 to Jan et al. describes a layered catalyst where an outer layer is bound to an inner cordierite material. In yet another example, Zou et al. {Catalysis Today, 2011, 168: 140-146) describes crystallization of IT A zeolite crystals on the surface of a FAU-type crystal. In each of these references, the second zeolite is obtained by using additional amounts of silicon and aluminum. That is, the silicon and aluminum is not obtained/derived from the first zeolite.

[0005] Despite the forgoing efforts, zeolites that are composite structures can be inefficient to produce on a commercial scale. Further, the composite materials can have adverse effects on pore size, reactant and product diffusion into and out of the materials, can ultimately reduce catalytic efficiency, and/or can contribute to deactivation of the catalyst.

SUMMARY OF THE INVENTION

[0006] A solution to the aforementioned problems associated with composite zeolites has been discovered. In particular, the solution of the present invention concerns a multi-layered or core/shell structured zeolite that includes two different zeolites having different silica (Si0 ₂ ) to alumina (Α1 ₂ 0 ₃ ) ratios (SARs). The second zeolite is in direct contact with the first zeolite defining an interface between the first and second zeolites. Notably, the silicon (Si) and optionally aluminum (Al), if present, in the second zeolite is from the first zeolite {i.e., the second zeolite is prepared from the Si and Al (if present) from the first zeolite. Without wishing to be bound by theory, it is believed that this creates a stronger interaction between the first and second zeolites when compared with the above-discussed composite zeolites. Further, the SAR ratio of the initial zeolite is maintained when Si and optional Al from this initial zeolite are used to create the second zeolite. Therefore, an overall target SAR ratio can be maintained while forming a second zeolite layer or shell from the first zeolite. The formation of this second layer in such a manner can be commercially scalable and/or can reduce costs associated with forming double layered or core/shell zeolites. Also, if the initial zeolite includes metal(s) {e.g., catalytic metal(s)) on its surface or impregnated within the initial zeolite, the formation of the second layer from the first layer can help reduce leaching of the metals. [0007] As explained in detail below, the process used to make the double layered or core/shell zeolites of the present invention includes an elegant dissolution/recrystallization process that can use the selection of templating agents to obtain the second layer or shell. In preferred instances, the first or initial zeolite (e.g., *BEA-type zeolite, FAU-type zeolite, MOR type zeolite, MWW type zeolite, LTA type zeolite, etc.) can have a more uniform defect density when compared with zeolites (e.g., MFI type zeolite or ZSM-5) that have defect densities concentrated in their respective cores. It is believed that the more uniform density allows for the hydroxyl group of the templating agent to begin solubilizing Si and/or Al around the surface of the first zeolite, thereby creating the outer second layer or shell rather than forming a hollow zeolite. Once produced, the zeolites of the present invention can be used in many commercial applications (e.g., adsorption/absorption applications, chemical reactions, and the like). In particular, the zeolites of the present invention can used in processes to make aromatic products (e.g., ethylbenzene, cumene) or hydrocarbon cracking of vacuum gas oil to make lower boiling (lighter) hydrocarbons.

[0008] In a particular aspect of the invention, a multi -layered or core/shell structured zeolite can include a first zeolite having a first silica (Si0 ₂ ) to alumina (A1 ₂ 0 ₃ ) (SAR) ratio (e.g., a SAR ratio of 5 < SAR < infinity (∞)) and a second zeolite that is in direct contact with the first zeolite defining an interface between the first and second zeolites. The second zeolite can be a pure silica zeolite or can have a second SAR ratio that is different than the first SAR ratio (e.g., <∞). In some aspects, the SAR ratio of the second zeolite can be greater than the SAR ratio of the first zeolite. The silicon (Si) and optionally aluminum (Al), if present, in the second zeolite can be from the first zeolite. The first and second zeolites can be different zeolites. By way of example, the first zeolite can be *BEA-type zeolite, a FAU- type zeolite, MOR type zeolite, MWW type zeolite, or LTA type zeolite, and the second zeolite can be a MFI-type zeolite (e.g., ZSM-5 or silicate-1) or a pure silica zeolite. As discussed in other parts of this application, which are incorporated by reference, other zeolites can be used for the first and second zeolites. In certain embodiments, the first and second zeolites can be first and second substantially planar zeolite layers. The first layer can have a thickness of 20 nm to 300 nm and the second layer can have a thickness of 5 nm to 30 nm. In some aspects, the zeolite can have a core/shell structure, where the first zeolite is the core and the second zeolite is the shell that substantially or completely encompasses the core. The core can have a particle size of 20 nm to 300 nm and the shell can have a thickness of 5 nm to 30 nm. Such a structure does not require a bonding or binding agent (e.g., an adhesive) to connect the two zeolites together to form double-layered or core/shell structured zeolite.

[0009] The zeolites of the present invention can include a metal or multiple metals. In some aspects, the zeolite of the present invention can include a catalytically active noble metal (e.g., silver (Ag), palladium (Pd), platinum (Pt), gold (Au), rhodium (Rh), ruthenium (Ru), rhenium (Re), iridium (Ir), osmium (Os), or any combination or alloys thereof), transition metals (e.g., copper (Cu), iron (Fe), nickel (Ni), zinc (Zn), manganese (Mn), chromium (Cr), molybdenum (Mo), tungsten (W), tin (Sn), or any combinations, or oxides, or alloys thereof), or combinations thereof.

[0010] A method to make zeolites of the present invention can include (a) obtaining a first zeolite having a first silica to alumina (SAR) ratio, (b) suspending the first zeolite in an aqueous solution that includes a hydroxide containing templating agent (e.g., tetrapropyl ammonium hydroxide (TPAOH)) to form a suspension, (c) heat-treating the suspension to obtain a dried material that has a multi-layered or core/shell structure with the second zeolite in direct contact with the first zeolite defining an interface between the first and second zeolites where the first and second zeolites are different, and (d) calcining the dried material to remove any remaining templating material to obtain the multi-layered or core/shell structured zeolite of the present invention having a second zeolite in direct contact with the first zeolite defining an interface between the first and second zeolites and the first and second zeolites are different. The first zeolite can be a *BEA-type zeolite and the hydroxide containing templating agent templates the formation of a MFI-type zeolite. During step (c), the hydroxyl group from the templating agent can solubilize silica and optionally alumina present in the outer portion of the first zeolite. The templating agent can also template the formation of a second zeolite on the surface of the first zeolite with the silicon (Si), and if present, the alumina (Al) from the solubilized silica and alumina of step (b). Heat-treating in step (c) can include subjecting the suspension to a temperature of greater than 100 °C to 250 °C, preferably 150 °C to 200 °C, for 12 hours to 96 hours, preferably 48 hours to 96 hours, and optionally followed by rinsing and drying the dried material. Calcining in step (d) can include subjecting the dried material to air at a temperature of 450 °C to 650 °C, preferably 500 °C to 600 °C, for 3 hours to 10 hours, preferably 4 hours to 8 hours. Notably, the SAR ratio of the first zeolite prior to process steps (b) to (d) is the same SAR ratio for the resulting double layered or core/shell zeolite, as the Si and Al, if present in the second zeolite, is from the first zeolite. Preservation of the SAR ratio of the starting zeolite can be maintained through the process of producing the double layered or core/shell zeolites of the present invention.

[0011] Methods for using the zeolites of the present invention in a chemical reaction (e.g., alkylation, hydrocracking or the like) are described. A method can include contacting the multi -layered or core/shell structured zeolite with a reactant stream to catalyze the reaction and produce a product stream. In some instances, the reactant stream includes an aromatic hydrocarbon and an olefin (e.g., ethylene or propylene), and the product stream comprises an alkyl aromatic compound(s) (e.g., ethylbenzene or cumene). In another aspect, the reactant stream is a vacuum gas oil stream (VGO) and the product stream includes hydrocarbons having an average lower boiling point than the average boiling point of the hydrocarbons in the VGO stream.

[0012] The following includes definitions of various terms and phrases used throughout this specification. [0013] 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%.

[0014] The terms "wt.%", "vol.%", or "mol.%" refers to a weight percentage of a component, a volume percentage of a component, or molar percentage of a component, respectively, based on the total weight, the total volume of material, or total moles, that includes the component. In a non-limiting example, 10 grams of component in 100 grams of the material is 10 wt.% of component.

[0015] The term "substantially" and its variations are defined to include ranges within 10%, within 5%, within 1%, or within 0.5%.

[0016] 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.

[0017] The term "effective," as that term is used in the specification and/or claims, means adequate to accomplish a desired, expected, or intended result.

[0018] The use of the words "a" or "an" when used in conjunction with the term "comprising" 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."

[0019] 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.

[0020] The zeolites 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 phase "consisting essentially of," in one non- limiting aspect, a basic and novel characteristic of the zeolites of the present invention is that they include two different zeolites where a second zeolite is in direct contact with the first zeolite defining an interface between the first and second zeolites and the Si and optionally Al, if present in the second zeolite, is from the first zeolite. [0021] 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.

BRIEF DESCRIPTION OF THE DRAWINGS

[0022] 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. [0023] FIG. 1A is an illustration of a core-shell zeolite of the present invention having a zeolite core and a zeolite shell.

[0024] FIG. IB is an illustration of a core-shell zeolite of the present invention having a zeolite core, and a noncontiguous zeolite shell.

[0025] FIG. 2 is an illustration of a multi-layered planar zeolite catalyst having a first zeolite layer and a second zeolite layer. [0026] FIG. 3 is a schematic of a system for the production of an alkyl aromatic hydrocarbon using the multi -layered or core/shell structured zeolite of the present invention.

[0027] FIG. 4 shows the normalized XRD pattern of (4A) BEA zeolite, (4B) MFI zeolite and (4C) double layer BEA-MFI zeolite. [0028] FIG. 5 shows the N ₂ isotherm of a BEA zeolite (top isotherm) and BEA-MFI zeolite of the present invention (bottom isotherm).

[0029] FIGS. 6A-6D show the SEM images of *BEA starting material (FIGS. 6 A and 6B) and a BEA-MFI zeolite of the present invention (FIGS. 6C and 6D).

[0030] FIG. 7 shows gas-chromatograms of the alkylation of benzene reaction using a comparative catalyst (top chromatogram) and the multi -layered or core/shell catalyst of the present invention (bottom chromatogram).

[0031] While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings. The drawings may not be to scale. DETAILED DESCRIPTION OF THE INVENTION

[0032] A discovery has been made that avoids problems associated with deactivation of zeolite-type catalysts. The discovery is based on creating a multi-layered or core/shell type structure that includes two different zeolites, where one of the zeolites (e.g., second zeolite) is formed from the silica and optionally alumina of the other zeolite (e.g., first zeolite). The second zeolite is in direct contact with the first zeolite defining an interface between the two zeolites. Notably, the multi-layered or core/shell structured zeolite does not require a bonding or binding agent (e.g., adhesive or composite) between the two zeolites to create a double-layered or core/shell structured zeolite. Metals (e.g., catalytic metals) can be incorporated into the zeolite using a variety of methods. The method of making the multi - layered or core/shell structured zeolite allows for dissolution of silica or some alumina from of the first zeolite (e.g., a *BEA-type zeolite, a FAU-type zeolite, MOR type zeolite, MFI type zeolite, MWW type zeolite, or LTA type zeolite), which then recrystallizes as a second zeolite layer having a different zeolite structure (e.g., a MFI-type zeolite or a pure silica zeolite) than the first zeolite. An MFI-type zeolite includes a ZSM-5 zeolite or a silicate- 1 zeolite. [0033] These and other non-limiting aspects of the present invention are discussed in further detail in the following sections.

A. Catalyst Structure

[0034] The zeolite catalyst of the present invention can include a core (e.g., a first zeolite) substantially or completely surrounded by a second zeolite (e.g., silica shell or a silica/alumina shell) where the first zeolite is different than the second zeolite and the second zeolite is in direct contact with first zeolite defining an interface. FIG. 1 A is an illustration of a core-shell zeolite 10 of the present invention having a zeolite core 12 and a zeolite shell 14. FIG. ID is an illustration of core-shell zeolite 10 of the present invention having zeolite core 12 and discontinuous zeolite shell 14. As illustrated in FIG. 1A, the core-shell structure can have a substantially spherical shape. The surface of zeolite core 12 is in full or substantially direct contact with the inner surface of zeolite shell 14 to form interface 16. In some embodiments, there are few or no voids between zeolite core 12 and the zeolite shell 14. As shown in FIG. IB, the zeolite 10 includes noncontiguous zeolite shell 14'. Portions (voids) 18 of zeolite core 12 are not covered by the zeolite shell 14'. Portions 18 can be the result of noncontiguous growth of the second zeolite on the surface of the zeolite core 12. The thickness of the second zeolite shell can range from 5 nm to 30 nm, 10 nm to 25 nm, 15 nm to 20 nm, or 5 nm, 6 nm, 7 nm, 8 nm, 9 nm, 10 nm, 1 1 nm, 12 nm, 13 nm, 14 nm, 15 nm, 16 nm, 17 nm, 18 nm, 19 nm, 20 nm, 21 nm, 22 nm, 23 nm, 24 nm, 25 nm 26 nm, 27 nm, 28 nm 29 nm, 30 nm or any value or range there between. The particle size of the first zeolite core can range from 20 nm to 300 nm, 50 nm to 250 nm, 100 nm to 200 nm, 125 nm to 150 nm, or 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, 100 nm, 1 10 nm, 120 nm, 130 nm, 140 nm, 150 nm, 160 nm, 170 nm, 180 nm, 200 nm, 210 nm, 220 nm, 220 nm, 230 nm, 240 nm, 250 nm, 260 nm, 270 nm, 280 nm or any value or range there between. [0035] Alternatively, the zeolite catalyst of the present invention can include two layers (e.g., substantially planar layers) where the first layer is a first zeolite and the second layer is the second zeolite that is in direct contact with the first zeolite. FIG. 2 is an illustration of a multi-layered planar zeolite catalyst having first zeolite layer 22 and second zeolite layer 24 (second zeolite). Referring to FIG. 2, the surface of first zeolite layer 22 can be in full or substantially direct contact with the surface of second zeolite layer 24 to form interface 26. In some embodiments, there are few or no voids between first zeolite layer 22 and second zeolite layer 24. Second zeolite layer 24 can have a thickness less than the thickness of the first zeolite layer. A thickness of the second zeolite layer can range from 5 nm to 30 nm, 10 nm to 25 nm, 15 nm to 20 nm, or 5 nm, 6 nm, 7 nm, 8 nm, 9 nm, 10 nm, 1 1 nm, 12 nm, 13 nm, 14 nm, 15 nm, 16 nm, 17 nm, 18 nm, 19 nm, 20 nm, 21 nm, 22 nm, 23 nm, 24 nm, 25 nm 26 nm, 27 nm, 28 nm 29 nm, 30 nm or any value or range there between. The thickness of the first zeolite layer can range from 20 nm to 300 nm, 50 nm to 250 nm, 100 nm to 200 nm, 125 nm to 150 nm, or 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, 100 nm, 1 10 nm, 120 nm, 130 nm, 140 nm, 150 nm, 160 nm, 170 nm, 180 nm, 200 nm, 210 nm, 220 nm, 220 nm, 230 nm, 240 nm, 250 nm, 260 nm, 270 nm, 280 nm or any value or range there between.

[0036] Depending on the application, the thickness or particle size of the core, shell, or layers can be tuned to a specific thickness or particle size as desired by modifying the amounts of materials used and/or the processing conditions, such as those discussed throughout this specification.

[0037] The double layered or core/shell zeolite can be porous and can include pores having a diameter of 2 nanometers or less, 0.1 nanometers to 0.5 nanometers, or 0.1 nm, 0.2 nm, 0.3 nm, 0.4 nm, 0.5 nm, 0.6 nm, 0.7 nm, 0.8 nm, 0.9 nm, 1 nm, 1.1 nm 1.2 nm, 1.3 nm, 1.4 nm, 1.5 nm, 1.6 nm, 1.7 nm, 1.8 nm, 1.9 nm, 2.0 nm or any value or range there between. In some embodiments, the surface area of the multi-layered or core/shell structured zeolite can be less than the surface area of the original zeolite (e.g., the first zeolite core material or the first zeolite layer material) used to make the zeolite of the present invention. The second zeolite layer or zeolite shell can have a silica to alumina ratio (SAR) greater than the SAR of the first zeolite layer or first zeolite core, respectively. The multi-layered or core/shell structured zeolite can have an increased surface area, increased micropore surface area, and an increased amount of strong acid sites, all of which can facilitate hydrogen transfer reactions. B. Method of Making the Multi-layered or Core/Shell Structured Zeolite

[0038] The multi-layered or core/shell structured zeolites of the present invention can be made using a dissolution/recrystallization method as exemplified in the Examples. By way of example, step 1 can include obtaining a starting zeolite having a first silica to alumina (SAR) ratio (for example, a *BEA-type zeolite having a SAR ratio of 5 < SAR < infinity (∞)). This starting zeolite can be manufactured or obtained from a commercial vendor. Notably, the SAR ratio of the starting zeolite can be maintained in the produced double-layered or core/shell zeolite of the present invention by using Si and optionally Al from the starting zeolite to produce the outer layer or shell of the double-layered or core/shell zeolite, respectively.

[0039] In a second step of the method, the first zeolite can be suspended in an aqueous solution that includes a hydroxide containing templating agent. The hydroxide containing templating agent can be any known agent capable of dissolving silica and optionally alumina present in the outer portion of the first zeolite. Non-limiting examples of the templating agent include a quaternary ammonium compound, a tertiary ammonium compound, or a tetramethyl ammonium hydroxide. Non-limiting examples of quaternary ammonium salts include tetrapropylammioum hydroxide (TPAOH), tetraethylammonium hydroxide (TEAOH), tetramethylammonium hydroxide (TMAOH), hexadecyltrimethylammonium hydroxide, dibenzyldimethylammonium hydroxide, benzyltriethylammonium hydroxide, and cetyltrimethylammonium hydroxide or alkyl derivatives thereof. In a preferred embodiment, TPAOH is used. The templating agent can be selected to create a desired zeolite shell or zeolite outer layer (e.g., TPAOH can be used to create an MFI-type zeolite). Therefore, the selection of the templating agent can be such that it matches a desired zeolite shell or zeolite outer layer of the core/shell or double layered zeolites of the present invention. In preferred instances, the templating agent is different than the templating agent used to form the core of the core/shell zeolite or the first or inner layer of the double layered zeolite of the present invention. [0040] In step 3, the resulting suspension can be heat-treated to produce the multi-layered or core/shell zeolite material 10 or 20. Heating the zeolite suspension in the presence of a quaternary ammonium salts can affect the resultant crystal morphology (size, shape, dispersion, surface area, distribution), and, thus, the activity of the zeolite formed. The heat treating can be a dissolution-recrystallization process under hydrothermal conditions. By way of example, the aqueous templated zeolite suspension can be heated at high vapor pressures. In a particular embodiment, the suspension is heated to 100 °C to 250 °C, preferably 150 °C to 200 °C, or about 170 °C for 12 to 96 hours, preferably about 72 hours under autogenous pressure, and then cooled to room temperature. Heat-treating can be performed in a pressure vessel, such as an autoclave, by a temperature-difference method, temperature-reduction method, or a metastable-phase technique. Without wishing to be bound by theory, it is believed that during the heat-treating, the silica and optionally alumina is dissolved and recrystallized as a second zeolite on the outer surface of the first zeolite upon cooling to form a precursor zeolite material. The precursor zeolite material can be isolated from the water using known separation techniques (e.g., filtration, centrifugation, or the like). The isolated precursor zeolite material can be dried, washed to remove any excess templating agent, and then dried at 100 °C to 150 °C, 110 °C to 130 °C, or about 110 °C.

[0041] In step 4 of the method, the dried precursor zeolite material can be calcined at a temperature of 450 °C to 650 °C, 500 °C to 600 °C, or 450 °C, 455 °C, 460 °C, 465 °C, 470 °C, 475 °C, 480 °C, 485 °C, 490 °C, 500 °C, 505 °C, 510 °C, 515 °C, 520 °C, 525 °C, 530 °C, 535 °C, 540 °C, 545 °C, 550 °C, 555 °C, 560 °C, 565 °C, 570 °C, 575 °C, 580 °C, 585 °C, 590 °C, 595 °C, or 600 °C, for 3 to 10 hours, or 4 to 8 hours or 5 to 7 hour, or 6 hours to obtain the multi-layered or core/shell structured zeolite of the present invention (e.g., zeolite 10 or zeolite 20 in FIGS. 1 and 2, respectively). Calcining of the material can remove any remaining template.

C. Materials

1. First Zeolite Material

[0042] The first zeolite material can be a naturally occurring zeolite, a synthetic zeolite, a zeolite that have other materials in the zeolite framework (e.g., phosphorous), or combinations thereof. X-ray diffraction (XRD) analysis and scanning electron microscopy (SEM) may be carried out to determine the properties of zeolite materials, including their crystallinity, size, and morphology. The network of such zeolites is made up of Si0 ₄ and A10 ₄ tetrahedra, which are joined via shared oxygen bridges. An overview of the known structures may be found, for example, in W. M. Meier, D. H. Olson and Ch. Baerlocher, "Atlas of Zeolite Structure Types", Elsevier, 5th edition, Amsterdam 2001. Non-limiting examples of zeolites include ABW, ACO, AEI, AEL, AEN, AET, AFG, AFI, AFN, AFO, AFR, AFS, AFT, AFX, AFY, AHT, ANA, APC, APD, AST, ATN, ATO, ATS, ATT, ATV, AWO, AWW, *BEA, BIK, BOG, BPH, BRE, CAN, CAS, CFI, CGF, CGS, CHA, CHI, - CLO, CON, CZP, DAC, DDR, DFO, DFT, DOH, DON, EAB, EDI, EMT, EPI, ERI, ESV, EUO, *EWT, FAU, FER, GIS, GME, GOO, HEU, IFR, ISV, ITE, ITH, ITG, JBW, KFI, LAU, LEV, LIO, LOS, LOV, LTA, LTL, LTN, MAZ, MEI, MEL, MEP, MER, MFI MFS, MON, MOR, MSO, MTF, MTN, MTT, MTW, MWW, NAT, NES, NON, OFF, OSI, PAR, PAU, PHI, RHO, RON, RSN, RTE, RTH, RUT, SAO, SAT, SBE, SBS, SBT, SFF, SGT, SOD, STF, STI, STT, TER, THO, TON, TSC, VET, VFI, VNI, VSV, WIE, WEN, YUG, or ZON structures, or mixed structures of two or more of the abovementioned structures. In some embodiments, the zeolite includes phosphorous to form an AIPOx structure. Non- limiting examples of AIPOx zeolites include AABW, AACO, AAEI, AAEL, AAEN, AAET, AAFG, AAFI, AAFN, AAFO, AAFR, AAFS, A AFT, AAFX, AAFY, AAHT, AANA, AAPC, AAPD, AAST, AATN, AATO, AATS, AATT, AATV, AAWO, AAWW, ABEA, ABIK, ABOG, ABPH, ABRE, ACAN, ACAS, ACFI, ACGF, ACGS, ACHA, ACHI, A- CLO, ACON, ACZP, ADAC, ADDR, ADFO, ADFT, ADOH, ADON, AEAB, AEDI, AEMT, AEPI, AERI, AESV, AEUO, A*EWT, AFAU, AFER, AGIS, AGME, AMFI, AGOO, AHEU, AIFR, AISV, AITE, AITH, AITG, AJBW, AKFI, ALAU, ALEV, ALIO, ALOS, ALOV, ALTA, ALTL, ALTN, AMAZ, AMEI, A MEL, AMEP, AMER, AMFS, AMON, AMOR, AMSO, AMTF, AMTN, AMTT, AMTW, AMWW, ANAT, A ES, ANON, AOFF, AOSI, APAR, APAU, APHI, ARHO, ARON, ARSN, ARTE, ARTH, ARUT, AS AO, AS AT, ASBE, ASBS, ASBT, ASFF, ASGT, ASOD, ASTF, ASTI, ASTT, ATER, ATHO, ATON, ATSC, AVET, AVFI, AVNI, AVSV, AWIE, AWEN, AYUG, or AZON structures, or mixed structures of two or more of the abovementioned structures. In particular embodiment, the zeolite is a porous zeolite in pure silica (Si/Al=∞) form or with a small amount of Al. Non-limiting examples of such zeolites include a FAU type structure (including X and Y structures), a MWW type structure, a *BEA type structure, a LTA type structure, a MFI type zeolite, a MOR type structure, an ITH type structure, a CHA type structure, a MER type structure, a MFE type structure, or a VFI type structure zeolites. Zeolites can be obtained from a commercial manufacturer such as Zeolyst (Valley Forge, Pennsylvania, U.S.A.). The SAR of the first zeolite can be greater than 5 and less than or equal to infinity. The first zeolite can be chosen based on the defect density concentration being more uniform throughout the material (e.g. a *BEA type zeolite) as opposed to zeolites that have defect density concentrated in the core (e.g., a MFI type zeolite). As used herein "defects" are the misalignment of zeolite particle nuclei between adjacent zeolite crystals extending through the thickness of the zeolite layer. Defects can be determined using spectroscopy methods, for example solid state NMR, X-ray absorption fine structure spectroscopy (EXAFS) and/or X-ray absorption near edge structure (XANES). In some embodiments, the first zeolite can be prepared using known methods (e.g., Zheng et al, Chem Letter, 2010, 39:330-31) or as demonstrated in the Examples section. In a non-limiting example, a β-zeolite (*BEA) can be prepared by dissolving a templating agent (e.g., tetraethyl ammonium chloride (TEACl)), sodium aluminate, and sodium oxide in an aqueous ammonia solution. To the clear solution, silica solution (e.g., colloidal silica) can be slowly added to the solution under stirring. The mixture can be stirred at room temperature for a given amount of time (e.g., 0.5 to 5 hours, or 1 hour), and then subjected to heat-treating under high temperature and pressure. In some instances, the suspension is heated under autogenous pressure at 130 °C to 200 °C, or 140 °C to 180 °C, or 140 °C to 145 °C, for 200 to 220 hours, or about 216 hours. Then, the heat-treated sample can be isolated (e.g., filtered or centrifuged), washed with water to remove any excess templating agent, and then dried at 100 °C to 150 °C, 1 10 °C to 130 °C, or about 1 10 °C. The dried solid can be calcined at a temperature of 450 °C to 650 °C, 500 °C to 600 °C, or 450 °C, 455 °C, 460 °C, 465 °C, 470 °C, 475 °C, 480 °C, 485 °C, 490 °C, 500 °C, 505 °C, 510 °C, 515 °C, 520 °C, 525 °C, 530 °C, 535 °C, 540 °C, 545 °C, 550 °C, 555 °C, 560 °C, 565 °C, 570 °C, 575 °C, 580 °C, 585 °C, 590 °C, 595 °C, or about 600 °C, for 3 to 10 hours, or 4 to 8 hours or 5 to 7 hour, or 6 hours to obtain a β-type zeolite.

2. Metals

[0043] The multi-layered or core/shell structured zeolite of the present invention can include one or more metals (e.g., metals in reduced form), metal compounds (e.g., metal oxides), or mixtures thereof ("collectively metals") of Column 1 or 2 metals, transition metals, post-transition metals, and lanthanides (atomic number 57-71) of the Periodic Table. Non-limiting examples of transition metals and post-transition metals include chromium (Cr), molybdenum (Mo), tungsten (W), manganese (Mn), iron (Fe), ruthenium (Ru), cobalt (Co), rhodium (Rh), nickel (Ni), palladium (Pd), copper (Cu), silver (Ag), gold (Au), zinc (Zn), osmium (Os), iridium (Ir), cadmium (Cd), tin (Sn), or gallium (Ga). In some embodiments, the metal material is a noble metal, for example, Ag, Pd, Pt, Au, Rh, Ru, Re, Ir, Os, or any combination or alloys thereof. In other embodiments, the metal material is a transition metal such as Cu, Fe, Ni, Zn, Mn, Cr, Mo, W, Sn, or any combinations, or oxides, or alloys thereof. The multi-layered or core/shell structured zeolite of the present invention can include up to 20 wt. % of the metal and/or metal oxide, from 0.1 wt.% to 20 wt. %, from 1 wt. % to 10 wt. %, or from 3 wt. % to 7 wt. % and all wt.% there between (e.g., 3.1 wt.%, 3.2 wt.%, 3.3 wt.%, 3.4 wt.%, 3.5 wt.%, 3.6 wt.%, 3.7 wt.%, 3.8 wt.%, 3.9 wt.%, 4 wt.%, 4.1 wt.%, 4.2 wt.%, 4.3 wt.%, 4.4 wt.%, 4.5 wt.%, 4.6 wt.%, 4.7 wt.%, 4.8 wt.%, 4.9 wt.%, 5 wt.%, 5.1 wt.%, 5.2 wt.%, 5.3 wt.%, 5.4 wt.%, 5.5 wt.%, 5.6 wt.%, 5.7 wt.%, 5.8 wt.%, 5.9 wt.%, 6 wt.%, 6.1 wt.%, 6.2 wt.%, 6.3 wt.%, 6.4 wt.%, 6.5 wt.%, 6.6 wt.%, 6.7 wt.%, 6.8 wt.%, and 6.9 wt.%)). In a specific embodiment, the multi-layered or core/shell structured zeolite includes about 5 wt. % of metal and/or metal oxide. The metals used to prepare the multi- layered or core/shell structured zeolite of the present invention can be provided in varying oxidation states as metallic, oxide, hydrate, or salt forms typically depending on the propensity of each metals stability and/or physical/chemical properties. The metals in the catalyst can also exist in one or more oxidation states. Preferably the metals or metal oxides used in the preparation of the mixed metal oxide catalyst are provided in stable oxidation states as complexes with monodentate, bidentate, tridentate, or tetradendrate coordinating ligands such as for example iodide, bromide, sulfide, thiocyanate, chloride, nitrate, azide, fluoride, hydroxide, oxalate, water, isothiocyanate, acetonitrile, pyridine, ammonia, ethylenediamine, 2,2'-bipyridine, 1, 10-phenanthroline, nitrite, triphenylphosphine, cyanide, carbon monoxide, or mixtures thereof. In a preferred aspect, the metals are impregnated into the zeolite catalysts as aqueous solutions of metal nitrate, metal nitrate hydrates, metal nitrate trihydrates, metal nitrate hexahydrates, or metal nitrate nonahydrates for example, nickel nitrate hexahydrate (Ni(N0 ₃ )2*6H ₂ 0), copper nitrate trihydrate Cu(N0 ₃ ) ₂ *3H ₂ 0, iron nitrate nonahydrate (Fe(N0 ₃ )3*9H ₂ 0), cobalt nitrate hexahydrate (Co(N0 ₃ ) ₂ *6H ₂ 0), chromium nitrate nonahydrate (Cr(N0 ₃ )3*9H ₂ 0), or zinc nitrate hexahydrate (Zn(N0 ₃ ) ₂ *6H ₂ 0). A non- limiting example of a commercial source of the above mentioned metals and metal oxides is Sigma Aldrich® (U.S.A).

D. Uses of the Multi-Layered or Core/Shell Structured Zeolites

[0044] Also disclosed is a method of producing a chemical product. The method can include contacting a reactant feed of a hydrocarbon with any one of the multi-layered or core/shell structured zeolite (e.g., zeolites 10 and/or 20 discussed above) and/or throughout this specification under sufficient conditions to produce a desired chemical product. The reactant feed can be a saturated hydrocarbon stream, an aromatic hydrocarbon stream, and/or a hydrocarbon stream having a boiling point of 315 °C to 595 °C or more at atmospheric pressure (e.g., Vacuum Gas Oil (VGO). The product stream can include alkylated hydrocarbons (e.g., ethylbenzene, cumene, or the like), gasoline, jet fuel, diesel, olefinic gases, or any combination thereof. The method can further include isolating, separating, and/or storing the produced product mixture.

[0045] In one particular aspect of the invention, a method is provided for producing alkyl aromatic hydrocarbons. The method can include reacting an alkene (e.g., ethylene or propylene) with an aromatic hydrocarbon (e.g., benzene) in the presence of a catalytic zeolite of the present invention under conditions sufficient to produce the alkyl aromatic hydrocarbon (e.g., ethylbenzene or cumene). Referring to FIG. 3, a schematic of system 30 for the production of an alkyl benzene such as ethylbenzene or cumene is depicted. System 30 can include a continuous flow reactor 32 and a reaction zone 34 that includes the multi- layered or core/shell structured zeolite 36 (e.g., zeolite 10 or 20 in FIGS. 1A-C and 2, respectively). A reactant stream that includes an alkene (e.g., ethylene, propylene, butylene, etc.,) and an aromatic hydrocarbon can enter the continuous flow reactor 32 via the feed inlet 38. In some instances, two feed streams enter the continuous flow reactor 32. In some instances, the catalytic material can be layered or in beds in the continuous flow reactor 32. The continuous flow reactor can be a fixed bed reactor or fluidized circulating reactor (e.g., an ebullating bed reactor). In some embodiments, any one of the feeds may include a gaseous diluent. The gaseous diluent may be, for example, nitrogen, helium, argon, carbon dioxide, or water, or any combination thereof. [0046] Reaction zone 34 and the reactant feed(s) can be heated to a temperature suitable for an aromatic alkylation reaction using known heating sources (e.g., heaters, heat exchangers, steam, oil, high temperature circulating fluid, or combinations thereof). Reactor 32 can be operated at atmospheric or elevated pressure. Contact of the alkene and the aromatic hydrocarbon with the double layered or core/shell zeolite catalyst 36 of the present invention under these conditions can produce a product stream that includes the alkyl aromatic hydrocarbon (e.g., ethylbenzene or cumene).

[0047] The product stream can exit continuous flow reactor 32 via product outlet 39, and be transported to a collection zone. In the collection zone, the alkyl aromatic hydrocarbon can be separated from the reactant feed stream using known separation techniques, for example, distillation, absorption, membrane technology, etc., to produce an alkyl aromatic hydrocarbon. The method can further include isolating and/or storing the produced alkyl aromatic hydrocarbon or the separated products.

EXAMPLES

[0048] 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.

Example 1

(Synthesis of A First Zeolite)

[0049] β-Zeolite: A *BEA-Zeolite was prepared by following the procedure of Zheng et al. (Chemistry Letters, 2010, 39, 330-331). Tetraethylammonium chloride (4.4 g TEAC1, > 98%, Sigma-Aldrich®, U.S. A), sodium aluminate (0.56 g, about 8% H ₂ 0, Strem Chemicals, U.S.A.) and sodium oxide (0.14 g, 80 wt.%, Sigma-Aldrich®, U.S.A.) were dissolved in deionized water (8.75 mL) and aqueous ammonia (1.45 mL, 32 wt.%, VWR Chemicals BDH Prolabo) to form a clear solution. Silica solution (9.5 g, Ludox SM-30, colloidal silica (30%), Sigma-Aldrich®, U.S.A.) was slowly added to the solution under agitation. The mixture was stirred for 1 h at room temperature, transferred to a Teflon liner having a volume of 45 mL, and the liner was put in an autoclave. The mixture was heat to 413 K (284 °C) and kept at 413 K for 216 h under static conditions. The resulting solid washed with water, and then recovered by centrifugation at 10,000 rpm for 15 minute, followed by washing with water three times. The washed solid product was recovered and dried overnight at 110 °C and calcined at 550 °C for 6 hours while ramping rate did not exceed 1 °C /minute. Around 2.5 g of a *BEA zeolite was obtained.

Example 2

(Synthesis of A Double Layered or Core/Shell Zeolite)

[0050] BEA zeolite from Example 1 was added to TPAOH (10 mL of 1 mol/L in water, Sigma-Aldrich®, U.S. A) and deionized H ₂ 0 (10 mL). The mixture was stirred for few minutes at 150 rpm, transferred to a Teflon liner of 45 mL, introduced into an autoclave, and heated at 170 °C for 72 hours. The sample was recovered by centrifugation at 10,000 rpm for 15 minute and washing with three times with water. The washed solid product was recovered and dried overnight at 110 °C and calcined at 550 °C for 6 hours while ramping rate did not exceed 1 °C /minute.

Example 3

(Characterization of the Double Layered Core/Shell Zeolite)

[0051] X-ray diffraction (XRD): XRD patterns were collected using an Empyrean X-ray diffractometer from PANalytical (the Netherlands) having a nickel-filtered CuKa X-ray source, a convergence mirror, and a PIXcelld detector. The scanning rate was 0.01 degrees over the range between 5 degrees and 80 degrees at 2 theta (Θ). FIGS. 4A-C show the normalized XRD pattern of (4A) BEA zeolite, (4B) MFI zeolite, and (4C) double layer BEA- MFI zeolite. XRD pattern (FIG. 4A) corresponded to the BEA zeolite with a composition of polymorph A and B equal to 50/50, ICDD: 00-056-0467. XRD pattern (FIG. 4B) corresponded to the pure silica MFI zeolite, ICDD: 01-070-4743. XRD pattern (FIG. 4C) corresponded to the double layer BEA-MFI zeolite. From the XRD data, it was determined that the double layer BEA-MFI zeolite possessed the signature of the BEA and the MFI zeolites.

[0052] Isothermal Analysis: Nitrogen adsorption/desorption isotherms of the BEA-MFI zeolite of the present invention was collected at 77 K (-196 °C) using a Micromeritics® ASAP 2010 instrument (Micromeritics®, USA). Before the measurement, approximately 100 mg of sample was degassed under vacuum (10 ^"6 bar) at 350 °C for 10 hours. FIG. 5 shows the N ₂ isotherm of the BEA-MFI zeolite. It can be noticed that the surface area of BEA-MFI material is lower than *BEA. That can be explained by the dissolution/recrystallization process. *BEA zeolite has a surface area of about 500 to 750 m ² g ^_1 , while MFI zeolites have a surface area of about 300 to 450 m ² g ^_1 . According to these results, it was expected to see a decrease of the BEA-MFI zeolite surface area given that MFI was being produced on the BEA surface.

[0053] Scanning Electron Microscopy (SEM): SEM analysis was performed using a Titan G2 80-300 kV transmission electron microscopy (FEI™, USA) operating at 300 kV equipped with a 4 k x 4 k CCD camera, a GIF Tridiem (Gatan, Inc.) and an energy-dispersive X-ray spectroscopy (EDS) detector (EDAX, USA). Field-emission SEM pictures were obtained with a FEI Quanta 600 FEG. FIG. 6 shows the SEM images of *BEA starting material (FIGS. 6A and 6B) and the *BEA-MFI of the present invention (FIGS. 6C and 6D). From the SEM, it was determined that the shape of the zeolite particle before and after treatment was completely different. Notably, the *BEA zeolite shape was almost spherical and some sticks were detected after the double layer treatment.

Example 3

(Production of Ethylbenzene from Ethylene and Benzene)

[0054] The catalyst (300 g) from Example 2 or a comparative zeolite (*BEA Si/Al =7.5) and benzene (10 mL) were introduced into a 100 mL PARR autoclave reactor. The comparative zeolite was the starting material in Example 2 for producing of the double- layered zeolite of the present invention as is a known catalyst for the alkylation of benzene. The reactor was pressurized to 10 bar (1 MPa) with pure ethylene. The reactor was stirred and the temperature was increased to 250 °C. After 72 h, the reaction was cooled and the liquid phase was analyzed by using an Agilent Technologies (USA) GC-MS (Agilent 7890b with a FID detector and HP 5MS UI columns, 0.25 micrometer and an Agilent 5977A Mass spectrometer). FIG. 7 shows the GC chromatogram for both experiments. The top chromatogram was the comparative catalyst (BEA Si/Al = 7.5) and the bottom chromatogram was the multi-layered or core/shell catalyst of the present invention. In FIG. 7, the peak at 2.2 min. was benzene, the peak at 4.3 min. was ethylbenzene, and the peaks having higher retention times are by-products of the alkylation reaction (e.g. at the 9.8 min was 1- methylpropylbenzene). Under these experimental conditions, the multi-layered or core/shell catalyst of the present invention produced less by-products (i.e., more selective) than the comparative (*BEA Si/Al=7.5) zeolite in the alkylation of benzene reaction.