Mesoporous zeolites and methods for preparing mesoporous zeolites

Abstract

This invention provides mesoporous zeolites and processes for preparing mesoporous zeolites.

Description

C2-8129 MESOPOROUS ZEOLITES AND METHODS FOR PREPARING MESOPOROUS ZEOLITES CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application filed October 31, 2024, under 35 U.S.C. §119(e), claims the benefit of U.S. Provisional Patent Application Ser. No. 63 / 547,005, filed November 02, 2023, entitled “MESOPOROUS ZEOLITES AND METHODS FOR PREPARING MESOPOROUS ZEOLITES,” the entire contents and substance of which are hereby incorporated by reference as if fully set forth below. TECHNICAL FIELD

[0002] This invention relates to mesoporous zeolites and methods for preparing mesoporous zeolites. BACKGROUND

[0003] Zeolites are often included as components of fluid cracking catalysts. In typical zeolite manufacturing processes, zeolites are crystallized from mixtures, typically slurries, that usually contain less than 25 wt% solids. A significant amount of water is usually present, which reduces yields and raises production costs.

[0004] Mesoporous zeolites are desirable, and improved methods for preparing zeolites having mesoporosity are continually sought. SUMMARY OF THE INVENTION

[0005] This invention provides zeolites having mesoporosity as well as methods for producing zeolites having mesoporosity. The processes described herein provide zeolites having mesoporosity. An organic template is not necessary to achieve the mesoporosity, and no post- treatment of the prepared zeolites is needed to obtain the mesoporosity. The processes of the present invention utilize slurries having relatively low amounts of water, which in turn provides increased production yields and greater energy efficiency. In the processes of this invention, the mesoporosity is formed in the zeolites during the crystallization step. This is advantageous compared to other known technologies, in which the mesoporosity is formed via an additional step, typically via removal of material from the zeolite crystal, by methods such as acid and / or baseC2-8129 leaching. At least some types of mesoporous zeolites formed by the processes of this invention, when used in a catalytic cracking process, provide higher yields of light olefins, especially propylene and / or C4 olefins.

[0006] An embodiment of this invention is a process for preparing mesoporous zeolites in the absence of an organic template. The process comprises A) i) pre-aging an aqueous zeolite precursor mixture comprising water, a silicon source, and an aluminum source to form a pre-aged precursor; and ii) concentrating the pre-aged precursor to form a concentrated pre-aged precursor; and iii) crystallizing the concentrated pre-aged precursor to obtain zeolites containing mesopores; or B) i) concentrating an aqueous zeolite precursor mixture comprising water, a silicon source, and an aluminum source to form a concentrated precursor; and ii) crystallizing the concentrated precursor by steam-assisted crystallization to obtain zeolites containing mesopores. These processes provide zeolites containing mesopores.

[0007] These and other embodiments and features of this invention will be still further apparent from the ensuing description and appended claims. FURTHER DETAILED DESCRIPTION OF THE INVENTION

[0008] As defined by IUPAC, mesopores have pore diameters of 2 nm to 50 nm, and micropores have pore diameters of less than 2 nm.

[0009] As used throughout this document, the phrases "zeolites having mesoporosity", "mesoporous zeolites"' and "zeolites containing mesopores" are used interchangeably.

[0010] Throughout this document, zeolites formed by a process involving a pre-aging step are sometimes referred to as "pre-aged zeolites."

[0011] Various types of mesoporous zeolites can be prepared in the practice of this invention. These types of zeolites include but are not limited to aluminosilicate zeolites, aluminum phosphate zeolites, gallium phosphate zeolites, silicon aluminum phosphate zeolites, metal aluminum phosphate zeolites (where metal represents a transition metal element), germanosilicate zeolites, borosilicate zeolites, beryllosilicate zeolites, zincosilicate zeolites, and titanosilicate zeolites.C2-8129

[0012] Some of the zeolites that can be prepared as mesoporous zeolites in the practice of this invention include FAU, MFI, MEL, IMF, MSE, MFS, MTT, CFI, FER, MWW, TUN, TON, MEI, EWS, EMT, OFF, ERI, BEA, ITH, LTA, LTL, MER, MTF, MOR, MTW, NES, EON, EUO, ABW, GIS, CHA, RHO, STF, AFI, ITW, STI, CSV, IFW, ITN, BPH, NAT, PCR, MRE, SSO, CAS, IFR, IFO, MAZ, SZR, SFE, STT, AEL, AEI, AFO, ISV, and ITE.

[0013] Preferred zeolites that can be prepared as mesoporous zeolites in the practice of this invention are zeolite Y, including HY, USY, dealuminated Y, RE-Y and RE-USY, ZSM-5, ZSM- 11, IM-5, MCM-68, ZSM-57, ZSM-23, CIT-5, ZSM-35, MCM-22, MCM-56, MCM-49, UZM-8, EMM-10, ITQ-2, ITQ-30, TNU-9, ZSM-22, ZSM-18, EMM-26, zeolite T, EMC -2, offretite, beta zeolite, ITQ-13, zeolite A, zeolite L, MCM-35, mordenite, ZSM-12, NU-87, ECR-1, EU-1, ZSM- 50, Li-A, Na-Pl, Na-P2, chabazite, SSZ-13, SAPO-34, zeolite RHO, SSZ-35, SAPO-5, ITQ-12, stilbite, CIT-7, ITQ-39, Linde Q (a synthetic BPH), UZM-4, natrolite, IPC-4, ZSM-48, SSZ-61, ITQ-4, ITQ-51, mazzite, ZSM-4, SUZ-4, SSZ-48, SSZ-23, SAPO-11, SAPO-31 AIPO-18, SAPO- 18, SAPO-41, ITQ-7, ITQ-3, SSZ-36, MCM-58. More preferred zeolites are pentasil zeolites, especially ZSM-5.

[0014] The processes of this invention utilize an aqueous zeolite precursor mixture, which is comprised of water, a silicon source, and an aluminum source. The amount of aluminum and silicon source present in the aqueous zeolite precursor mixture depends on the desired silicon to aluminum molar ratio (SAR) of the resulting zeolite, and on which zeolite is being made.

[0015] Suitable silicon sources include sodium silicate, sodium meta-silicate, stabilized silica sols, silica gels, polysilicic acid, tetraethyl orthosilicate, fumed silicas, precipitated silicas, and combinations of any two or more of the foregoing.

[0016] Doped silica sols, for example, can be obtained by preparing a silica sol from water glass and an acid (e.g., sulfuric acid), and exchanging the sodium ions with the desired dopant. Alternatively, water glass, an acid (e.g., sulfuric acid), and a dopant are coprecipitated to form a doped silica sol.

[0017] Suitable aluminum sources include aluminum salts, such as Al2(SO4)3, AlCl3, AIPO4, Al2(HPO4)3, and Al(H2PO4)3, and water-insoluble aluminum compounds, e.g., alumina and aluminum trihydrate (Al(OH)3) such as gibbsite and bauxite ore concentrate, thermally treated aluminum trihydrate such as flash-calcined aluminum trihydrate, boehmite, pseudoboehmite,C2-8129 aluminum chlorohydrol, aluminum nitrohydrol, sodium aluminate, and combinations of any two or more of the foregoing.

[0018] Doped aluminum sources can be prepared by preparation of the aluminum source in the presence of the dopant, impregnation of the aluminum source with the dopant, or ion exchanging the aluminum source with the dopant. Doped boehmite or pseudoboehmite, for example, can be prepared by hydrolysis of aluminum alkoxide in the presence of a dopant, hydrolysis and precipitation of aluminum salts in the presence of a dopant, or by aging a slurry of (thermally treated) aluminum trihydrate, amorphous gel alumina, or less crystalline (pseudo)boehmite in the presence of a dopant.

[0019] Other sources of silicon and aluminum may also be used, wherein both the silicon and aluminum are supplied by the same source material. Examples include, but are not limited to, sands and clays such as kaolin, illinite, and bentonite. These sands and clays may be used as-is or undergo a treatment to adjust the silicon and aluminum content in the clays or sands. Example treatments may include acid or base leaching of silicon, aluminum, or other elements found in the sand or clay. Additional treatments may also include the addition of silicon or aluminum using aforementioned silicon or aluminum sources. These clays may also contain other elements such as titanium, magnesium, iron, sodium, calcium, zirconium, phosphorous, cerium, barium, zinc, boron, lithium, and rare earth metals.

[0020] Suitable dopants for the aluminum and / or the silicon source include compounds comprising rare earth metals such as Ce, La, Y, Gd, Eu, Pr, Sm, Ho, Nd, Er, Yb, or Tb; alkaline and alkaline earth metals such as Mg, Ca, K, Na, and Ba, transition metals such as Zr, Mn, Fe, Ti, Ag, Au, Cu, Ni, Zn, Mo, W, V, and Sn, actinides, noble metals such as Rh, Ru, Pt and Pd, group III, IV, or V elements such as Ga, B, In, Ge and / or P. Preferred dopants include P, La, Ga, Fe, Y, Mn, Ag, Ti, Cu, Zn, Pr, Ce, In, Gd, Eu, and Yb; more preferred are P, Mn, Ge, Ga, La, Y, and Zn. The optional dopant(s) present in the silicon and / or aluminum source and the dopant in the doped non-zeolitic seeds can be the same or different.

[0021] The pH of the aqueous zeolite precursor mixture depends on the zeolite to be crystallized. Suitable acids or bases can be added to the aqueous zeolite precursor mixture to adjust the pH depending on the zeolite being produced. Suitable inorganic acids include sulfuric acid, nitric acid, and hydrochloric acid. Suitable inorganic bases include sodium hydroxide, lithium hydroxide, potassium hydroxide, cesium hydroxide, ammonium hydroxide, magnesiumC2-8129 hydroxide, and calcium hydroxide. Other acids or bases, including organic acids and bases, can be used to adjust the pH of the aqueous zeolite precursor mixture.

[0022] To form the aqueous zeolite precursor mixture, the water, silicon source, and aluminum source are combined. The combining can be accomplished by any of the methods known in the art for preparing aqueous zeolite precursor mixtures. The aqueous zeolite precursor mixture typically contains about 25 wt% solids or less, preferably about 20 wt% solids or less, more preferably about 15 wt% solids or less, relative to the total weight of the aqueous zeolite precursor mixture. Usually, the aqueous zeolite precursor mixture contains about 1 wt% to about 25 wt% solids, preferably about 5 wt% to about 20 wt% solids, more preferably about 10 wt% to 20wt% solids, relative to the total weight of the aqueous zeolite precursor mixture.

[0023] In the processes of this invention, some of the steps may be considered to be carried out under hydrothermal conditions because the step or steps involve heating in the presence of water (sometimes in the form of steam).

[0024] Some of the processes of this invention have a pre-aging step. In these processes, after the pre-aging step, the pre-aged precursor formed thereby is concentrated and then crystallized. Optionally, an aging step can be performed after the concentrating step but before the crystallizing step. The crystallizing step can be a steam-assisted crystallization. In these processes having a pre-aging step, zeolites having mesoporosity are formed. Because the processes involving a preaging step can be performed with or without an aging step, the process steps include a) preaging, concentrating, and crystallizing, where the crystallizing may or may not be steam-assisted crystallization; or b) preaging, concentrating, aging, and crystallizing, where the crystallizing may or may not be steam-assisted crystallization.

[0025] In the pre-aging step, an aqueous zeolite precursor mixture is heated at one or more temperatures in the range of about 25°C to below the zeolite's crystallization temperature, usually about 25°C to about 300°C, preferably about 40°C to about 230°C, more preferably about 50°C to about 185°C, still more preferably about 75°C to about 180°C. In terms of steam pressure, the pressure is preferably about one atmosphere to about 30 atmospheres (0.1 MPa to 3.04 MPa). The duration of the pre-aging step is typically about 5 minutes to about 200 hours, preferably about 15 minutes to about 48 hours. The pre-aging step can be carried out in a vessel, process piping, a heat exchanger, or other process equipment.C2-8129

[0026] As used throughout this document, the phrase "pre-aged precursor" refers to the substance obtained at the end of the pre-aging step. In some instances, the pre-aged precursor appears to be a gel, and in other instances the pre-aged precursor appears to be a slurry, and in other instances appears to be a paste. When the amount of water in pre-aged precursor is very low, the pre-aged precursor may have a powder-like appearance.

[0027] After the pre-aging step, a concentrating step is carried out on the pre-aged precursor. The pre-aging step and the concentrating step can be carried out in the same vessel or reactor.

[0028] In the concentrating step, the pre-aged precursor is concentrated by removing water therefrom to obtain a concentrated pre-aged precursor having a desired solids content (concentration). Preferably, the concentrated pre-aged precursor has a concentration of about 30 wt% solids or more, preferably about 40 wt% solids or more, more preferably about 50 wt% solids or more, relative to the total weight of the concentrated pre-aged precursor. In some embodiments, the concentrated pre-aged precursor has a concentration of about 30 wt% to about 95 wt% solids, preferably about 40 wt% to about 85 wt% solids, more preferably about 50 wt% to about 80 wt% solids, relative to the total weight of the concentrated pre-aged precursor. In terms of water removal, the concentrating step typically removes about 5 wt% or more, preferably about 10 wt% or more, more preferably about 15 wt% or more, of the water content of the pre-aged precursor.

[0029] When the concentrated pre-aged precursor has a concentration above 95 wt% solids, but less than 100% solids, the process may still provide mesoporous zeolites. At a concentration of 100% solids, the process provides products having very low amounts of mesopores. If the concentrating step removed too much water, resulting in a concentration that is higher than desired, water may be combined with the concentrated pre-aged precursor to lower the concentration to the desired value.

[0030] Concentrating (water removal) can be performed any one or more of a variety of techniques. Such techniques include applying thermal energy, filtration, decantation, and centrifugation. Thermal energy techniques include evaporation, flash drying, spray drying, freeze drying, fluidized bed drying, and drum drying. Thermal energy may be obtained from steam, heated gases, such as air and / or an inert gas, electrical heating, and / or gas heating.

[0031] The optional aging step can be carried out with or without additional water added to the concentrated pre-aged precursor. In the optional aging step, the concentrated pre-aged precursor is heated at one or more temperatures in the range of about 25°C to below the zeolite'sC2-8129 crystallization temperature, usually about 25°C to about 300°C, preferably about 40°C to about 230°C, more preferably about 50°C to about 175°C, still more preferably about 75°C to about 150°C. The duration of the aging step is typically about 1 minute to about 200 hours, preferably about 15 minutes to about 48 hours, more preferably about one hour to about 36 hours. The aging step can be carried out in a vessel, process piping, a heat exchanger, or other process equipment.

[0032] In the crystallizing step, the concentrated pre-aged precursor is heated at one or more temperatures in the range of about 60°C to about 300°C, preferably about 100°C to 250°C, more preferably about 150°C to about 200°C. The crystallizing step is carried out for a time of about 1 minute to about 48 hours, preferably about 15 minutes to about 36 hours, more preferably about 30 minutes to about 24 hours, even more preferably about one hour to about 12 hours. In some crystallization steps, the water removed is in vapor form, and preferably is vented, preferably periodically, from the reactor or reaction zone in which the crystallization is conducted.

[0033] In some embodiments, this crystallizing step is a steam-assisted crystallization. In the steam-assisted crystallization, the concentrated pre-aged precursor, whether or not aged after the concentrating step, is subjected to steam-assisted crystallization. Steam-assisted crystallization is typically carried out in a sealed system, such as an autoclave. During the steam-assisted crystallization, the concentrated pre-aged precursor is heated at one or more temperatures in the range of about 60°C to about 300°C, preferably about 100°C to 250°C, more preferably about 150°C to about 200°C. The crystallizing step is carried out for a time of about 1 minute to about 48 hours, preferably about 15 minutes to about 36 hours, more preferably about 30 minutes to about 24 hours, even more preferably about one hour to about 12 hours. At the end of the steam- assisted crystallization, mesoporous zeolites are obtained.

[0034] Steam-assisted crystallization is typically carried out in a sealed vessel, to which steam is injected, or in which steam is generated from liquid water that is not in contact with the concentrated pre-aged precursor. In steam-assisted crystallization, liquid water is not brought into contact with the concentrated pre-aged precursor. One way of operating when liquid water is used to generate steam is to have an open container of the concentrated pre-aged precursor and a separate open container of water present in a sealed autoclave. If desired, during the steam-assisted crystallization the partial pressure of the steam can be decreased by introducing one or more other gases or a mixture of gases to maintain the desired total pressure (about one atmosphere to about 30 atmospheres, 0.1 MPa to 3.04 MPa) in the crystallization step. The other gases can be nitrogen,C2-8129 argon, or helium; air is a mixture of gases that can be used. In some steam-assisted crystallizations, steam is continuously introduced into the crystallization and continuously removed from the crystallization while maintaining the desired pressure in the crystallization reactor or reaction zone.

[0035] Some of the processes of this invention form mesoporous zeolites by steam-assisted crystallization without a pre-aging step. These processes have a concentrating step followed by a crystallizing step in which the crystallizing is accomplished by steam-assisted crystallization, but do not have a pre-aging step. Optionally, an aging step can be performed after the concentrating step but before the steam-assisted crystallization. In these processes using steam-assisted crystallization, zeolites having mesoporosity are formed. Because the processes involving steam- assisted crystallization can be performed with or without an aging step, the process steps include a) concentrating and then crystallizing by steam-assisted crystallization; or b) concentrating, aging, and then crystallizing by steam-assisted crystallization.

[0036] In the concentrating step, the aqueous zeolite precursor mixture is concentrated by removing water therefrom to obtain a concentrated precursor having a desired solids content (concentration). Preferably, the concentrated precursor has a concentration of about 20 wt% solids or more, preferably about 30 wt% solids or more, more preferably about 50 wt% solids or more, relative to the total weight of the concentrated precursor. In some embodiments, the concentrated precursor has a concentration of about 20 wt% to about 95 wt% solids, preferably about 30 wt% to about 85 wt% solids, more preferably about 50 wt% to about 80 wt% solids, relative to the total weight of the concentrated precursor. In terms of water removal, the concentrating step typically removes about 5 wt% or more, preferably about 10 wt% or more, more preferably about 15 wt% or more, of the water content of the aqueous zeolite precursor mixture.

[0037] When the concentrated precursor has a concentration above 95 wt% solids, but less than 100% solids, the process may still provide mesoporous zeolites. At a concentration of 100% solids, the process provides products having very low amounts of mesopores. If the concentrating step removed too much water, resulting in a concentration that is higher than desired, water may be combined with the concentrated precursor to lower the concentration to the desired value.

[0038] As used throughout this document, the phrase "concentrated precursor" refers to the substance obtained at the end of the concentrating step. In some instances, the concentrated precursor appears to be a gel, and in other instances the concentrated precursor appears to be aC2-8129 slurry, and in other instances appears to be a paste. When the amount of water in concentrated precursor is very low, the concentrated precursor may have a powder-like appearance.

[0039] The optional aging step can be carried out with or without additional water added to the concentrated precursor. In the optional aging step, the concentrated precursor is heated at one or more temperatures in the range of about 25°C to below the zeolite's crystallization temperature, usually about 25°C to about 300°C, preferably about 40°C to about 230°C, more preferably about 50°C to about 175°C, still more preferably about 75°C to about 150°C. The duration of the aging step is typically about 1 minute to about 200 hours, preferably about 15 minutes to about 48 hours, more preferably about one hour to about 36 hours. The aging step can be carried out in a vessel, process piping, a heat exchanger, or other process equipment.

[0040] In the steam-assisted crystallization, the concentrated precursor, whether or not aged after the concentrating step, is subjected to steam-assisted crystallization. Steam-assisted crystallization is typically carried out in a sealed system, such as an autoclave. During the steam-assisted crystallization, the concentrated precursor is heated at one or more temperatures in the range of about 60°C to about 300°C, preferably about 100°C to 250°C, more preferably about 150°C to about 200°C. The crystallizing step is carried out for a time of about 1 minute to about 48 hours, preferably about 15 minutes to about 36 hours, more preferably about 30 minutes to about 24 hours, even more preferably about one hour to about 12 hours. At the end of the steam-assisted crystallization, mesoporous zeolites are obtained.

[0041] Steam-assisted crystallization is typically carried out in a sealed vessel, to which steam is injected, or in which steam is generated from liquid water that is not in contact with the concentrated precursor. In steam-assisted crystallization, liquid water is not brought into contact with the concentrated precursor. One way of operating when liquid water is used to generate steam is to have an open container of the concentrated precursor and a separate open container of water present in a sealed autoclave. If desired, during the steam-assisted crystallization the partial pressure of the steam can be decreased by introducing one or more other gases or a mixture of gases to maintain the desired total pressure (about one atmosphere to about 30 atmospheres, 0.1 MPa to 3.04 MPa) in the crystallization step. The other gases can be nitrogen, argon, or helium; air is a mixture of gases that can be used. In some steam-assisted crystallizations, steam is continuously introduced into the crystallization and continuously removed from the crystallization while maintaining the desired pressure in the crystallization reactor or reaction zone.C2-8129

[0042] Mesoporous zeolites made in the practice of the processes of this invention are compositions of the invention. Some of the mesoporous zeolites made by the processes of this invention have about 75% or more of their aluminum content as framework aluminum and / or about 20% or less of their aluminum content as non-framework aluminum, especially pentasil zeolites, more especially ZSM-5. In some embodiments, the mesoporous zeolites made by the processes of this invention appear to retain 45% or more of the aluminum as framework aluminum after steam treatment, especially pentasil zeolites, more especially ZSM-5. In other embodiments, the mesoporous zeolites made by the processes of this invention have about 75% or more of their aluminum content as framework aluminum and / or about 20% or less of their aluminum content as non-framework aluminum, and appear to retain 45% or more of the aluminum as framework aluminum after steam treatment, especially pentasil zeolites, more especially ZSM-5.

[0043] In some embodiments of the invention, the processes of the invention create enough mesopores to provide zeolites having mesoporous surface areas of about 40 m2 / g or more, preferably about 50 m2 / g or more, still more preferably about 80 m2 / g or more, as measured by argon adsorption, especially for pentasil zeolites, more especially ZSM-5. In some embodiments, the processes of the invention, especially when a pre-aging step is part of the process, create enough mesopores to provide zeolites having about 20% or more, preferably about 25% or more, of their surface area as mesoporous surface area, especially for pentasil zeolites, more especially ZSM-5.

[0044] In other embodiments of the invention, the processes of the invention, especially when steam-assisted crystallization is performed without a pre-aging step as part of the process, create enough mesopores to provide zeolites having about 0.06 cm3 / g or more, preferably about 0.07 cm3 / g or more, of mesopore volume, as determined by argon adsorption and calculated by nonlocal density functional theory.

[0045] In still other embodiments of the invention, the processes of the invention, especially when a pre-aging step is part of the process, create enough mesopores to provide zeolites having about 0.10 cm3 / g or more, preferably about 0.11 cm3 / g or more, of mesopore volume, as determined by argon adsorption and calculated by nonlocal density functional theory. In some embodiments, the processes of the invention, especially when a pre-aging step is part of the process, create enough mesopores to provide zeolites having about 35% or more, preferably aboutC2-8129 40% or more, of their pore volume as mesoporous pore volume, especially for pentasil zeolites, more especially ZSM-5.

[0046] In yet other embodiments of the invention, the processes of the invention create enough mesopores to provide zeolites having about 0.10 cm3 / g or more, preferably about 0.11 cm3 / g or more, of mesopore volume, as determined by argon adsorption and calculated by nonlocal density functional theory, and having mesoporous surface areas of about 40 m2 / g or more, preferably about 50 m2 / g or more, still more preferably about 80 m2 / g or more, as measured by argon adsorption.

[0047] In some preferred embodiments of the invention, when the zeolites are produced with a pre-aging step, the zeolites have about 0.10 cm3 / g or more, preferably about 0.11 cm3 / g or more, of mesopore volume, as determined by argon adsorption and calculated by nonlocal density functional theory; and / or have about 75% or more of their aluminum content as framework aluminum and / or about 20% or less of their aluminum content as non-framework aluminum; and provide zeolites having mesoporous surface areas of about 40 m2 / g or more, preferably about 50 m2 / g or more, still more preferably about 80 m2 / g or more, as measured by argon adsorption. In these preferred embodiments of the invention, the zeolites often have about 20%, preferably about 25%, or more of their surface area as mesoporous surface area, and / or about 35% or more, preferably about 40% or more, of their pore volume as mesoporous pore volume. Preferably, the zeolites in these embodiments are pentasil zeolites, especially ZSM-5.

[0048] In other preferred embodiments of the invention, when the zeolites are produced by steam crystallization without a pre-aging step, the zeolites have about 0.06 cm3 / g or more, preferably about 0.07 cm3 / g or more, of mesopore volume, as determined by argon adsorption and calculated by nonlocal density functional theory; and / or have about 75% or more of their aluminum content as framework aluminum and / or about 20% or less of their aluminum content as non-framework aluminum; and provide zeolites having mesoporous surface areas of about 40 m2 / g or more, preferably about 50 m2 / g or more, still more preferably about 80 m2 / g or more, as measured by argon adsorption. Preferably, the zeolites in these embodiments are pentasil zeolites, especially ZSM-5.

[0049] The mesoporous zeolites produced in the practice of this invention may be used in fluid catalytic cracking catalysts and additives useful in such catalysts. When used as catalysts for olefin cracking, some of the mesoporous zeolites produced in the practice of this invention, especially pentasil zeolites, more especially ZSM-5, exhibit improved olefin yields, especially propyleneyields, and in some instance improved yields of butenes. In addition, the mesoporous zeolites of the instant invention may be used to improve the performance of adsorbents, alkylation catalysts, isomerization catalysts, catalysts used in the cracking of biogenic or waste plastic-containing feedstocks, catalysts used in the alcohol-to-jet fuel applications, including alcohol dehydration, and methanol-to-olefins, methanol-to-gasoline, and methanol-to-jet fuel processes and technologies.

[0050] In a typical olefin cracking process, a gaseous olefin or mixture of gaseous olefins, optionally in combination with an inert gas, usually helium, nitrogen, and / or argon, is brought into contact with a mesoporous zeolite composition of the invention at one or more elevated temperatures, typically about 200°C to about 600°C, preferably about 300°C to about 550°C. The olefins typically have four to about eight carbon atoms; olefins having six carbon atoms, especially 1-hexene, are preferred. In the olefin cracking processes, the mesoporous zeolite compositions of the invention have the same features and preferences described above.

[0051] The following examples are presented for purposes of illustration and are not intended to impose limitations on the scope of this invention. EXAMPLES

[0052] For characterization of the mesoporous zeolites in the Examples and accompanying Tables, one or more of the following characterization methods were employed.

[0053] The specific surface area, more particularly the Brunauer-Emmett-Teller specific surface area (BET SA), was determined by argon adsorption at 87 K.

[0054] The mesopore surface area (MeSA) was determined by a t-plot method from data from an argon adsorption at 87 K. The relative amount (%) of mesoporous surface area was determined by dividing the measured mesoporous surface area by the total measured specific surface area of the zeolite.

[0055] The mesopore volume, micropore volume, total pore volume, and the pore size distribution of the fresh and steamed zeolites were determined by nonlocal density functional theory (NLDFT) calculations from measured argon adsorption isotherms following examples in the literature including Thommes, M., "Textural Characterization of Zeolites and Ordered Mesoporous Materials by Physical Adsorption," in Stud. Surf. Sci. Catal., vol.168, J. Cejka et al.,Oxford, UK: Elsevier B.V., 2007, 495-524. The % mesopore volume is determined by dividing the measured mesoporous volume by the total measured pore volume.

[0056] In the tables below, PV is an abbreviation for pore volume; μPV is an abbreviation for micropore volume, and MePV and MesoPV are abbreviations for mesopore volume. Also in the tables below, NLDFT is an abbreviation for nonlocal density functional theory.

[0057] Powder x-ray diffraction (XRD). The x-ray powder diffraction analyses were performed on a D8 ADVANCE powder diffractometer (Bruker Inc.) which used a CuKα anode as the x-ray source (λ=1.54060 Å).

[0058] Solid state27Al NMR. Solid state nuclear magnetic resonance spectroscopy with magic- angle spinning (MAS) was performed in an NMR spectrometer (Bruker Ascend 500 Spectrometer with the magnet at a1H frequency of 500 MHz).

[0059] Catalytic results were determined with an inline gas chromatograph (GC; Agilent 6890) equipped with an FID detector was used to obtain catalytic conversion and product yields on a wt% carbon basis. Conversion was calculated by subtracting the total GC area of remaining C6olefins (C6=isomerization products) in the product from the feed hexene and dividing by the feed hexene. conversion (%) = (C6=feed − C6=products) / (C6=feed) x 100 Relative product yields were calculated by dividing the specific product's GC area by the total area. Product selectivity was calculated by dividing the product yield by the conversion. EXAMPLE 1

[0060] Several ZSM-5 zeolites were made by pre-aging, concentrating, and then crystallizing aqueous ZSM-5 precursor mixtures. The crystallization temperature for all runs was 170°C; the crystallization time for all runs was 17 hours. The pre-aging temperature for the zeolite precursor mixtures and concentration of the solids at the end of the concentrating step were varied; the pre- aging time for all runs was 4 hours. The product mesoporous ZSM-5 zeolites were calcined at 600°C for one hour and subjected to several measurements; some of the samples were measured fresh (as calcined), and other samples were steamed (788°C, 5 hr.) after calcining. Results are summarized in Tables 1A-1C below.C2-8129 TABLE 1ARunPre-agingAr BET Ar Relative NLDFT Relative Post-conc Treatment surface area MeSA amt. MesoPV amt. T, °C solids (m2 / g) (m2 / g) MeSA (cm3 / g) MesoPV 1a 100 50 wt% fresh 336.9 86.5 26% 0.122 44% 1b 100 50 wt% steamed 284.8 40.6 14% 0.115 44% 2a 100 60 wt% fresh 293.9 108.7 37% 0.172 60% 2b 100 60 wt% steamed 233.6 52.9 23% 0.147 59% 3a 140 60 wt% fresh 298.5 129.1 43% 0.246 69% 3b 140 60 wt% steamed 225.7 58.7 26% 0.211 70% 4a 140 70 wt% fresh 326.7 174.1 53% 0.221 66% 4b 140 70 wt% steamed 219.3 58.9 27% 0.185 67%C2-8129 TABLE 1B Post NLDFT NLDFT RunPre-aging-concTreatmentMeSAT, °C solids retained MesoPV μPV retained retained 1a 100 50 wt% fresh 46.9% 94.0% 96.5% 1b 100 50 wt% steamed 2a 100 60 wt% fresh 45.5% 85.9% 90.2% 2b 100 60 wt% steamed 3a 140 60 wt% fresh 48.7% 85.4% 84.8% 3b 140 60 wt% steamed 4a 140 70 wt% fresh 33.8% 83.4% 80.6% 4b 140 70 wt% steamed

[0061] At lower concentrations of solids in the post-concentrated mixtures, mesopore retention appears to be more affected by the pre-aging temperature, or the pre-aging temperature has a greater effect for lower concentrations of solids in the post-concentrated mixtures. TABLE 1C ZSM-5 Preaged Preaged Standard*Standard*Pre-aging T 100°C 100°C N / A N / A Post-conc. solids 50 wt% 50 wt% N / A N / A Treatment fresh steamed fresh steamed 27Al NMR at 55 ppm (framework)83.6% 47.6% 70.9% 32.9%27Al NMR not at 55 ppm (extra-framework)16.4% 52.4% 29.1% 67.1%Framework Al retained 56.9% 46.4% * Comparative run; standard ZSM-5 was prepared by techniques known in the art, and is equivalent to commercially-available ZSM-5.C2-8129

[0062] For Table 1C, the27Al NMR results indicate that the mesoporous ZSM-5 has more framework aluminum, and retains a greater percentage of framework aluminum after steam treatment. EXAMPLE 2

[0063] Olefin cracking tests were performed in a pulsed fixed bed reactor system. The mesoporous zeolite sample (10 mg) was placed in a quartz reactor tube and heated to and maintained at 480°C in a continuous 50 mL / min He flow. 1-Hexene (1 µL injection volume) was injected into the He flow at a rate corresponding to a zeolite to olefin ratio of 10:1 (wt / wt). Results are summarized in Tables 2A-2B below. C6 isomers were considered to be unreacted feed. TABLE 2A C6=catalytic cracking – fresh zeolites Run a b c d e f g ZSM-5 pre-aged pre-aged pre-aged pre-aged pre-aged pre-aged std.*Pre-aging T100°C 100°C 100°C 140°C 140°C 140°C N / APost-conc. solids50 wt% 60 wt% 70 wt% 50 wt% 60 wt% 70 wt% N / AConversion 96.5% 95.4% 96.2% 96.6% 96.2% 96.0% 97.5% C3=yield 22.9% 25.0% 24.4% 22.4% 24.0% 25.2% 19.7% *Comparative run; standard ZSM-5 was prepared by techniques known in the art, and is equivalent to commercially-available ZSM-5. TABLE 2B C6= catalytic cracking – steamed zeolites Run A B C D E F G ZSM-5 std.1std.1pre-aged pre-aged pre-aged std.1std.1Pre-aging TN / A N / A 100°C 100°C 100°C N / A N / APost-conc. solidsN / A N / A 50 wt% 50 wt% 50 wt% N / A N / ASample size25 mg 10 mg 5 mg 10 mg 15 mg 15 mg 20 mg Ethane yield 0.00 0.00 0.07 0.08 0.08 0.00 0.00C2-8129 C2=yield 0.7 1.6 2.4 3.8 4.5 2.3 2.9 Propane yield 0.03 0.09 0.08 0.19 0.27 0.18 0.28 C3=yield 8.3 18.4 24.6 37.1 42.0 23.9 28.0 C4=yield 3.7 10.6 7.6 13.7 17.1 15.8 20.8 BTEX yield30.08 0.02 0.02 0.05 0.06 0.02 0.08 Conversion 15.9 39.7 38.9 62.8 73.5 55.2 68.7 1 Comparative run; standard ZSM-5 was prepared by techniques known in the art, and is equivalent to commercially-available ZSM-5. 2 Amount of zeolite used in the catalytic run. 3 Benzene, toluene, ethylbenzene, and xylenes.

[0064] Table 2A shows that cracking of 1-hexene with catalysts containing fresh ZSM-5 prepared by pre-aging provided significantly increased propene yields. Table 2B shows that cracking of 1-hexene with catalysts containing steamed ZSM-5 prepared by pre-aging provided significantly increased yields of ethylene, propylene, and C4olefins. EXAMPLE 3

[0065] Standard ZSM-5 samples (ZSM-5 prepared by techniques known in the art and equivalent to commercially-available ZSM-5) having different post-concentration solids content were subjected to steam-assisted crystallization, directly after concentrating the aqueous zeolite precursor mixture to the desired concentration. The steam crystallization was conducted at 170°C for 8 hours in an autoclave with water evaporating from a vessel separate from the vessel containing the concentrated ZSM-5 precursor. Properties of the obtained mesoporous ZSM-5 zeolites are summarized in Table 3. TABLE 3 Post-conc. Ar BET NLDFT solids surface area Ar MeSA MesoPV (m2 / g) (m2 / g) (cm3 / g) 20 wt% 335.6 147.8 0.078 30 wt% 342.5 189.4 0.082 40 wt% 315.7 129.0 0.083C2-8129 50 wt% 410.2 218.9 0.108 60 wt% 353.1 172.1 0.069 70 wt% 336.5 143.2 0.071 80 wt% 325.4 120.5 0.081

[0066] Further embodiments of the invention include, without limitation:

[0067] A) A process for preparing zeolites containing mesopores in the absence of an organic template, which process comprises a) i) pre-aging an aqueous zeolite precursor mixture comprising water, a silicon source, and an aluminum source to form a pre-aged precursor; ii) concentrating the pre-aged precursor to form a concentrated pre-aged precursor; and iii) crystallizing the concentrated pre-aged precursor to obtain zeolites containing mesopores; or b) i) concentrating an aqueous zeolite precursor mixture comprising water, a silicon source, and an aluminum source to form a concentrated precursor; and ii) crystallizing the concentrated precursor by steam-assisted crystallization to obtain zeolites containing mesopores.

[0068] B) The process of A) wherein the silicon source is sodium silicate, sodium meta-silicate, stabilized silica sols, silica gels, polysilicic acid, tetraethyl orthosilicate, fumed silicas, precipitated silicas, or a combination of any two or more of the foregoing; and / or the aluminum source is Al2(SO4)3, AlCl3, AIPO4, Al2(HPO4)3, and Al(H2PO4)3, alumina, aluminum trihydrate, aluminum chlorohydrol, aluminum nitrohydrol, sodium aluminate, or a combination of any two or more of the foregoing.

[0069] C) The process of A) or B) wherein the aqueous zeolite precursor mixture has a concentration of about 1 wt% solids to about 25 wt% solids relative to the total weight of the aqueous zeolite precursor mixture.

[0070] D) The process of any one of A)-C) wherein the concentrating step in a) or b) is conducted at one or more temperatures in the range of about 25°C to about 300°C.

[0071] E) The process of any one of A)-D) whereinC2-8129 in a), the concentrated pre-aged precursor has a concentration of about 20 wt% solids to about 95 wt% solids relative to the total weight of the concentrated pre-aged precursor; or in b), the concentrated precursor has a concentration of about 20 wt% solids to about 95 wt% solids relative to the total weight of the concentrated precursor.

[0072] F) The process of any one of A)-E) wherein the crystallizing step in a) or b) is conducted at one or more temperatures in the range of about 60°C to about 300°C.

[0073] G) The process of any one of A)-F) wherein in a), the pre-aging step is conducted at one or more temperatures in the range of about 25°C to about 300°C.

[0074] H) The process of any one of A)-G) wherein in a), the crystallizing is by steam-assisted crystallization.

[0075] I) The process of any one of A)-G) wherein in a), the concentrated pre-aged precursor is subjected to aging before the crystallizing.

[0076] J) The process of I) wherein the aging step is conducted at one or more temperatures in the range of about 25°C to about 300°C.

[0077] K) The process of any one of A)-F) wherein in b), the concentrated precursor is subjected to aging before the crystallizing.

[0078] L) The process of K) wherein the aging step is conducted at one or more temperatures in the range of about 25°C to about 300°C.

[0079] M) The process of any one of A)-L) wherein the zeolite is a pentasil zeolite.

[0080] N) The process of any one of A)-L) wherein the zeolite is ZSM-5.

[0081] O) A mesoporous zeolite composition in which the mesoporous zeolites have about 0.06 cm3 / g or more of mesopore volume, as determined by argon adsorption and calculated by nonlocal density functional theory; mesoporous surface areas of about 40 m2 / g or more, as measured by argon absorption; and / or about 75% or more of their aluminum content as framework aluminum.

[0082] P) The mesoporous zeolite composition of O) wherein about 20% or less of the zeolite aluminum content is non-framework aluminum; and / or the zeolites retain 45% or more of the aluminum as framework aluminum after steam treatment.

[0083] Q) The mesoporous zeolite composition of O) or P) wherein about 20% or more of the surface area is mesoporous surface area, and / or about 35% or more of the pore volume is mesoporous pore volume.C2-8129

[0084] R) The mesoporous zeolite composition of Q) wherein about 25% or more of the surface area is mesoporous surface area, and / or about 40% or more of the pore volume is mesoporous pore volume.

[0085] S) The mesoporous zeolite composition of any one of O)-R) wherein the zeolite is a pentasil zeolite.

[0086] T) The mesoporous zeolite composition of any one of O)-S) wherein the zeolite is ZSM- 5.

[0087] U) A process for olefin cracking, which process comprises bringing a gaseous olefin or mixture of gaseous olefins into contact with a mesoporous zeolite composition at one or more elevated temperatures, wherein the mesoporous zeolites have about 0.06 cm3 / g or more of mesopore volume, as determined by argon adsorption and calculated by nonlocal density functional theory; mesoporous surface areas of about 40 m2 / g or more, as measured by argon absorption; and / or about 75% or more of their aluminum content as framework aluminum.

[0088] V) The process as in U) wherein the gaseous olefin is in combination with an inert gas, and optionally the olefin has six carbon atoms, and the elevated temperatures, typically about 200°C to about 600°C.

[0089] W) The process as in U) or V) wherein the mesoporous zeolite composition has about 20% or less of the zeolite aluminum content as non-framework aluminum; about 20% or more of the surface area as mesoporous surface area, and / or about 35% or more of the pore volume as mesoporous pore volume; optionally wherein the zeolite is a pentasil zeolite, preferably ZSM-5.

[0090] Components referred to by chemical name or formula anywhere in the specification or claims hereof, whether referred to in the singular or plural, are identified as they exist prior to coming into contact with another substance referred to by chemical name or chemical type (e.g., another component, a solvent, or etc.). It matters not what chemical changes, transformations and / or reactions, if any, take place in the resulting mixture or solution as such changes, transformations, and / or reactions are the natural result of bringing the specified components together under the conditions called for pursuant to this disclosure. Thus, the components are identified as ingredients to be brought together in connection with performing a desired operation or in forming a desired composition. Also, even though the claims hereinafter may refer toC2-8129 substances, components and / or ingredients in the present tense ("comprises", "is", etc.), the reference is to the substance, component or ingredient as it existed at the time just before it was first contacted, blended or mixed with one or more other substances, components and / or ingredients in accordance with the present disclosure. The fact that a substance, component or ingredient may have lost its original identity through a chemical reaction or transformation during the course of contacting, blending or mixing operations, if conducted in accordance with this disclosure and with ordinary skill of a chemist, is thus of no practical concern.

[0091] The invention may comprise, consist, or consist essentially of the materials and / or procedures recited herein.

[0092] As used herein, the term "about" modifying the quantity of an ingredient in the compositions of the invention or employed in the methods of the invention refers to variation in the numerical quantity that can occur, for example, through typical measuring and liquid handling procedures used for making concentrates or use solutions in the real world; through inadvertent error in these procedures; through differences in the manufacture, source, or purity of the ingredients employed to make the compositions or carry out the methods; and the like. The term about also encompasses amounts that differ due to different equilibrium conditions for a composition resulting from a particular initial mixture. Whether or not modified by the term "about", the claims include equivalents to the quantities.

[0093] Except as may be expressly otherwise indicated, the article "a" or "an" if and as used herein is not intended to limit, and should not be construed as limiting, the description or a claim to a single element to which the article refers. Rather, the article "a" or "an" if and as used herein is intended to cover one or more such elements, unless the text expressly indicates otherwise.

[0094] This invention is susceptible to considerable variation in its practice. Therefore the foregoing description is not intended to limit, and should not be construed as limiting, the invention to the particular exemplifications presented hereinabove.

Claims

C2-8129 THAT WHICH IS CLAIMED IS:

1. A process for preparing zeolites containing mesopores in the absence of an organic template, which process comprises A) i) pre-aging an aqueous zeolite precursor mixture comprising water, a silicon source, and an aluminum source to form a pre-aged precursor; ii) concentrating the pre-aged precursor to form a concentrated pre-aged precursor; and iii) crystallizing the concentrated pre-aged precursor to obtain zeolites containing mesopores; or B) i) concentrating an aqueous zeolite precursor mixture comprising water, a silicon source, and an aluminum source to form a concentrated precursor; and ii) crystallizing the concentrated precursor by steam-assisted crystallization to obtain zeolites containing mesopores.

2. The process of Claim 1 wherein the silicon source is sodium silicate, sodium meta-silicate, stabilized silica sols, silica gels, polysilicic acid, tetraethyl orthosilicate, fumed silicas, precipitated silicas, or a combination of any two or more of the foregoing; and / or the aluminum source is Al2(SO4)3, AlCl3, AIPO4, Al2(HPO4)3, Al(H2PO4)3, alumina, aluminum trihydrate, aluminum chlorohydrol, aluminum nitrohydrol, sodium aluminate, or a combination of any two or more of the foregoing.

3. The process of Claim 1 wherein the aqueous zeolite precursor mixture has a concentration of about 1 wt% solids to about 25 wt% solids relative to the total weight of the aqueous zeolite precursor mixture.

4. The process of Claim 1 wherein the concentrating step in A) or B) is conducted at one or more temperatures in the range of about 25°C to about 300°C.

5. The process of Claim 1 wherein in A), the concentrated pre-aged precursor has a concentration of about 20 wt% solids to about 95 wt% solids relative to the total weight of the concentrated pre-aged precursor; or in B), the concentrated precursor has a concentration of about 20 wt% solids to about 95 wt% solids relative to the total weight of the concentrated precursor.C2-8129 6. The process of Claim 1 wherein the crystallizing step in A) or B) is conducted at one or more temperatures in the range of about 60°C to about 300°C.

7. The process of Claim 1 wherein in A), the pre-aging step is conducted at one or more temperatures in the range of about 25°C to about 300°C.

8. The process of Claim 1 wherein in A), the crystallizing is by steam-assisted crystallization.

9. The process of Claim 1 wherein in A), the concentrated pre-aged precursor is subjected to aging before the crystallizing.

10. The process of Claim 9 wherein the aging step is conducted at one or more temperatures in the range of about 25°C to about 300°C.

11. The process of Claim 1 wherein in B), the concentrated precursor is subjected to aging before the crystallizing.

12. The process of Claim 11 wherein the aging step is conducted at one or more temperatures in the range of about 25°C to about 300°C.

13. The process of Claim 1 wherein the zeolite is a pentasil zeolite.

14. The process of Claim 1 wherein the zeolite is ZSM-5.

15. A mesoporous zeolite composition in which the mesoporous zeolites have about 0.06 cm3 / g or more of mesopore volume, as determined by argon adsorption and calculated by nonlocal density functional theory; mesoporous surface areas of about 40 m2 / g or more, as measured by argon absorption; and / or about 75% or more of their aluminum content as framework aluminum.

16. The mesoporous zeolite composition of Claim 15 wherein about 20% or less of the zeolite aluminum content is non-framework aluminum; and / or the zeolites retain 45% or more of the aluminum as framework aluminum after steam treatment.C2-8129 17. The mesoporous zeolite composition of Claim 15 wherein about 20% or more of the surface area is mesoporous surface area, and / or about 35% or more of the pore volume is mesoporous pore volume.

18. The mesoporous zeolite composition of Claim 17 wherein about 25% or more of the surface area is mesoporous surface area, and / or about 40% or more of the pore volume is mesoporous pore volume.

19. The mesoporous zeolite composition of Claim 15 wherein the zeolite is a pentasil zeolite.

20. A process for olefin cracking, which process comprises bringing a gaseous olefin or mixture of gaseous olefins into contact with a mesoporous zeolite composition, at one or more elevated temperatures, wherein the mesoporous zeolites have about 0.06 cm3 / g or more of mesopore volume, as determined by argon adsorption and calculated by nonlocal density functional theory; mesoporous surface areas of about 40 m2 / g or more, as measured by argon absorption; and / or about 75% or more of their aluminum content as framework aluminum.

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