Hydrothermal synthesis method of sphere-like ZSM-48 zeolites and use thereof in isomerization

Abstract

Sphere-like ZSM-48 zeolites are prepared by mixing a source of alumina, silica, an organic structure directional agent, and a mineralizing agent together in water to form an aqueous mixture; combining a morphology modifier and optionally zeolite seeds with the mixture forming a gel; subjecting the gel to a hydrothermal process and allowing the ZSM-48 zeolites to crystallize as a precipitate in a mother liquid; and separating the precipitate from the mother liquid. The formed ZSM-48 zeolites have a silica to alumina ratio in the range of 50 to 150 and a sphere-like morphology defined by one or more of a loose bulk density of > 0.15 g / cm3 and a sphericity of > 0.5. The ZSM-48 zeolites may be incorporated into a catalyst by combining the zeolites with a binder and at least one other acidic support to form a powder mixture that is then shaped into a zeolite extrudate.

Description

HYDROTHERMAL SYNTHESIS METHOD OF SPHERE-LIKEZSM-48 ZEOLITES AND USE THEREOF IN ISOMERIZATIONFIELD

[0001] This disclosure generally relates to a method of forming a sphere-like ZSM- 48 zeolite using a hydrothermal process.BACKGROUND

[0002] The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.

[0003] ZSM-48 zeolites generally exhibit a high silica to alumina ratio (SAR) and are known fortheir unique unidimensional pore channel structure. These zeolites are often used as a catalyst by the petrochemical industry in hydrocracking and dewaxing processes. The 1 -dimensional pore structure of the ZSM-48 zeolites assist in selectively cracking larger hydrocarbon molecules into smaller, more valuable products, such as gasoline and diesel fuel. In addition, these zeolites can effectively be used to catalyze the isomerization of linear alkanes into branched alkanes, which are more suitable for use as high-octane fuels.

[0004] Conventional ZSM-48 zeolites having needle-like morphology exhibit a large aspect ratio of > 8:1 due to excessive growth along the main channel, which inherently limits the diffusion of mass throughout. This unidirectional growth compels reactants to experience a longer residence time in narrow pores, thereby, intensifying carbon deposition that tends to lead to deactivation of the catalyst. Moreover, needle-like ZSM-48 zeolites exhibit a lower loose bulk density, e.g., ~0.1 g / cm3, which results in less catalytic active sites per unit space, poor mechanical stability, and low mass transfer. The determination of how to obtain ZSM-48 zeolites that exhibit a lower aspect ratio (e.g., shaped in the form of spheres, cubes, etc.) in order to shorten the mass diffusion path has become a significant industrial challenge.

[0005] A more efficient way to ensure high catalytic performance is to synthesize ZSM-48 particles that exhibit a sphere-like morphology. These sphere-like particles would generally consist of nano-size crystals that have a shortened crystal length in order for the reactants to reach the active sites more quickly, and the products that form to exit the pores more effectively.

[0006] The introduction of fluoride ions (F-) during the preparation of ZSM-48 zeolites through the use of ammonium fluoride (NF F) or sodium fluoride (NaF) as morphology modifiers has led to the synthesis of spherical ZSM-48 zeolites. The presence of F" ions is believed to induce the formation of ZSM-48 spheres by promoting surface Si- OH condensation. Spherical ZSM-48 zeolites are capable of providing enhanced catalytic performance due to the positive impact of having shortened channels for mass transfer. In addition, spherical ZSM-48 zeolites have the potential of being a new catalyst for m-xylene isomerization. Unfortunately, the high toxicity associated with these fluoride compounds has limited the industrial production and use of spherical ZSM-48 zeolites. Thus, a need exists for the development of safer and more cost-effective morphology modifiers that may be used to synthesize sphere-like ZSM- 48 zeolites.DRAWINGS

[0007] In order that the disclosure may be well understood, there will now be described various forms thereof, given by way of example, reference being made to the accompanying drawings.

[0008] Fig. 1 is a flowchart describing a method of preparing sphere-like ZSM-48 zeolites formed according to the teachings of the present disclosure.

[0009] Fig. 2 is a flowchart describing a method of preparing a catalyst that incorporates the ZSM-48 zeolite formed according to the method of Fig. 1 .

[0010] Fig. 3 is a schematic representation of various shapes for a catalyst extrudate formed according to the method of Fig. 2.

[0011] Fig. 4A is a graphical representation of an x-ray diffraction (XRD) pattern measured for a sphere-like ZSM-48 zeolite prepared according to the teachings of the present disclosure.

[0012] Fig. 4B is a graphical representation of an x-ray diffraction (XRD) pattern measured for a conventional ZSM-48 zeolite.

[0013] Fig. 4C is a graphical representation of an x-ray diffraction (XRD) pattern for another sphere-like ZSM-48 zeolite prepared according to the teachings of the present disclosure.

[0014] Fig. 5A is a scanning electron micrograph (SEM) demonstrating the morphology of the sphere-like ZSM-48 zeolite of Fig. 4A.

[0015] Fig. 5B is a scanning electron micrograph (SEM) demonstrating the needlelike or rod-like morphology of the conventional ZSM-48 zeolite of Fig. 4B.

[0016] Fig. 5C is a scanning electron micrograph (SEM) demonstrating the morphology of the sphere-like ZSM-48 zeolite of Fig. 4C.

[0017] The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way.DETAILED DESCRIPTION

[0018] The following description is merely exemplary in nature and is in no way intended to limit the present disclosure or its application or uses. For example, the sphere-like ZSM-48 zeolite made and used according to the teachings contained herein is described throughout the present disclosure in conjunction with a catalyst for de-waxing or hydroisomerization that improve the cold flow properties of fuels and lubricants in order to more fully illustrate the composition and the use thereof. The incorporation and use of such sphere-like ZSM-48 zeolites in other catalysts used for naphtha cracking, methanol-to-hydrocarbon conversion, isomerization of xylenes, pyrolysis of alkanes or low density polyethylene, and the dehydration and isomerization of carbohydrates, as well as in other applications is contemplated to be within the scope of the present disclosure. It should be understood that throughout the description, corresponding reference numerals indicate like or corresponding parts and features.

[0019] The present disclosure generally provides a method of forming a ZSM-48 zeolite having a sphere-like morphology, a silica to alumina ratio (SAR) > 50, and a morphology that is spherical or close to being spherical in shape. Referring to Fig. 1 , this method generally comprises providing 3 a source of alumina, providing 5 a source of silica, providing 7 an organic structure directional agent (OSDA), and providing 9 a mineralizing agent. These sources of alumina 3, silica 5, OSDA 7, and mineralizing agent 9 are mixed 10 together in water to form an aqueous gel composition. Then, a morphology modifier and, optionally, a zeolite seed may be combined 15 with the aqueous gel composition. The gel composition is subjected 20 to a hydrothermal process in order for the sphere-like ZSM-48 zeolites to crystallize, thereby, forming a crystalline precipitate of the ZSM-48 zeolites and a mother liquid. The crystalline precipitate is separated 25 from the mother liquid. The ZSM-48 zeolites formed bythis method 1 has a sphere-like morphology and a silica to alumina ratio (SAR) that is in the range of 50 to 150.

[0020] The gel composition formed upon mixing together the aqueous mixture containing the sources of alumina, silica, organic structure directional agent (OSDA), mineralizing agent and morphology modifier with the optional zeolite seed generally comprises the following molar ratios:wherein the “M” in M2O represents the alkali metal arising from the mineralizing agent. Alternatively, the ratio of the morphology modifier to silica is in the range of 0.01 to 0.09; alternatively, from 0.025 to 0.075.

[0021] The amount of the zeolite seed added 15 to the gel composition may comprise from 0.0% to 5.0% by mass relative to the overall mass of the ZSM-48 zeolite formed. Alternatively, the amount of zeolite seed added to the gel composition is > 0.0%; alternatively, between 0.1 % and 3.5%; alternatively, from about 0.5% to about 3.0%.

[0022] Alternatively, the gel composition comprises the following molar ratios:

[0023] Still referring to Fig. 1 , the source of alumina is provided 3, without limitation, as one or more of alumina hydroxide, sodium aluminate, and aluminum sulfate. Alternatively, the source of alumina consists entirely of alumina hydroxide, sodium aluminate, or aluminum sulfate.

[0024] The source of silica is provided 5, without limitation, as at least one of colloidal silica, sodium silicate, and tetraethyl orthosilicate (TEOS). Alternatively, the source ofsilica consists entirely of colloidal silica, sodium silicate, or tetraethyl orthosilicate (TEOS).

[0025] The source of the organic structure directional agent (OSDA) is provided 7, without limitation, as hexamethonium bromide (HMBr), hexamethonium chloride (HMCI), or a mixture or combination thereof. Alternatively, the OSDA consists entirely of either HMBr or HMCI.

[0026] The source of the mineralizing agent is provided 9, without limitation as sodium hydroxide (NaOH), potassium hydroxide (KOH), or a combination thereof. Alternatively, the mineralizing agent consists entirely of either NaOH or KOH.

[0027] The morphology modifiers that are added 15 to the gel composition may include, but not be limited to, dimethyl carbonate (DMC), sodium dodecyl sulfate (SDS), or a combination thereof. Alternatively, the morphology modifier consists entirely of DMC or SDS.

[0028] The optional zeolite seed, when present, may be provided 15 as one from the group consisting of beta zeolites, a ZSM-48 zeolite, any other low framework density zeolite, and a combination thereof. Several specific examples of other low framework density zeolites include, without limitation, faujasite (FAU) zeolites, Erionite-Mordenite type (EMT) zeolites, and ITQ-40, which is a synthetic zeolite having extra-large pores.

[0029] The hydrothermal process to which the gel composition is subjected 20 may be conducted at a temperature that ranges from 135°C to 200°C for a predetermined amount of time. Alternatively, the temperature ranges from about 140°C to 190°C; alternatively, from 150°C to 180°C. The predetermined amount of time may range from about 12 hours to about 5 days; alternatively, 1 day (25 hours) to 3 days (72 hours); alternatively, from 20 hours to 50 hours.

[0030] The hydrothermally synthesized ZSM-48 zeolite obtained 25 from the method 1 has molar silica to alumina ratio (SAR) that is between 50 to 150; alternatively, 60 to 140; alternatively, 70 to 120; alternatively, 80 to 110.

[0031] The hydrothermally synthesized ZSM-48 zeolites formed according to the present disclosure also have a particle size that is between 0.5 pm and 10 pm; alternatively, between 0.75 pm and 7.5 pm; alternatively, about 1.0 pm to about 5.0 pm. The particle size being determined via the use of scanning electron microscopy (SEM) or another light scattering method, such as a laser particle size analyzer.

[0032] The hydrothermally synthesized ZSM-48 zeolites have a sphere-like morphology that consists of nano-size crystals having a shorter length then that ofconventional ZSM-48 zeolites. Controlling the sphere-like morphology of the particles is beneficial for the use of zeolites in many applications, as the morphology of the zeolites may influence the efficiency of adsorption, catalysis, as well as any other processes affected by the particle’s morphology.

[0033] For the purpose of this disclosure, the sphere-like nature of the ZSM-48 zeolites hydrothermally synthesized by the method of Fig. 1 may be defined by one or more of the following properties: (1 ) the sphericity determined for the particles and / or (2) the loose bulk density associated with the particles. Alternatively, the sphere-like morphology of the particles represents a combination of more than one of the preceding properties. In other words, the sphere-like morphology may be determined as a function of both of these properties. The sphericity for the sphere-like particles may be determined via the use of scanning electron microscopy (SEM) or another optical measurement technique.

[0034] The sphericity of a sphere-like particle may be estimated by determining the ratio of the smallest diameter of the particle to the largest diameter of that particle. The closer this ratio is to 1 .0, the closer the particle shape is to that of a sphere. The sphere-like ZSM-48 particles formed according to Fig. 1 exhibit an average sphericity value that is greater than or equal to 0.50; alternatively, at least 0.65; alternatively, > 0.75; alternatively, 0.80 or higher; alternatively, between 0.90 and 0.99. The sphericity of the formed particles is always < 1 .0.

[0035] The hydrothermally synthesized ZSM-48 zeolites may have a loose bulk density (LBD) that is greater > 0.15 g / cm3; alternatively, > 0.20 g / cm3; alternatively, the LBD is > 0.22 g / cm3. The loose bulk density (LBD) is defined as being the mass of the zeolites divided by the volume that the zeolites occupy when they are in a loose, non-compacted, or poured state.

[0036] The hydrothermally synthesized ZSM-48 zeolites have an average specific surface area that is greater than 200 m2 / g; alternatively, greater than 300 m2 / g. The specific surface area may be measured or determined according to Brunauer-Emmett- Teller (BET) theory and analysis.

[0037] According to another aspect of the present disclosure, a method of forming a catalyst for use in dewaxing and isomerization applications is provided. Referring now to Fig. 2, this method 50 generally comprises the steps of forming 1 the sphere-like ZSM-48 zeolites according to Fig. 1 ; combining 55 the ZSM-48 zeolites with a binder and at least one other acidic support to form a powder mixture; and then shaping 60the powder mixture into a zeolite extrudate. This zeolite extrudate may function in any given application as the catalyst. However, when desirable, this zeolite extrudate may further be impregnated with at least one additional metal to form the desired catalyst.

[0038] An extrudate represents the ZSM-48 zeolite after it has been shaped into a specific structure designed to improve its physical properties and suitability for use in a predetermined industrial application. The shaping process may involve any known or conventional method of extrusion or shaping of catalyst materials. The selection of the shaping process may affect the performance of the catalyst by influencing porosity, surface area, and the distribution of active sites due to interactions formed among binders, zeolites, and any other additives that may be present.

[0039] The zeolite extrudate may take the form of any shape suitable for use as a catalyst in the intended application. The shape of the zeolite extrudate may include, but not be limited to, a cylinder, a trilobe, a quadrilobe, a wagon wheel, a daisy, a multiple hole cylinder or monolith, a sphere, a pellet, or a ring. Referring now to Fig.3, the zeolite extrudate 75 may alternatively be a cylinder 80, a trilobe 85, a quadrilobe 90, or a wagon wheel 95. The diameter (D) of the zeolite extrudate 75 may range from about 2 mm up to about 6 mm.

[0040] Referring once again to Fig. 2, the amount of the ZSM-48 zeolite that is combined 55 with the binder and the at least one other acidic support may comprise an amount that ranges from about 15% to 85% by mass; alternatively, from 20% to 80% by mass; alternatively, 25% to 75% by mass; alternatively, 30% to 65% by mass relative to the overall mass of the zeolite extrudate. According to one aspect of the present disclosure the sphere-like ZSM-48 exhibits a silica to alumina ratio (SAR) in the range of 70 to 120.

[0041] The amount of the binder that is combined 55 with the ZSM-48 zeolite and the at least one other acidic support may comprise an amount that ranges from about 3% to 30% by mass; alternatively, 5% to 25% by mass; alternatively, 7.5% to 20% by mass relative to the overall mass of the zeolite extrudate. The composition of the binder may include, without limitation, clay, colloidal silica, Boehmite, gamma alumina, silica doped alumina, or a combination thereof. Alternatively, the composition is selected as one from the group consisting of clay, colloidal silica, Boehmite, gamma alumina, and silica doped alumina.

[0042] The amount of the at least one other acidic support that is combined 55 with the ZSM-48 zeolite and the binder may comprise an amount that ranges from about3% to 60% by mass; alternatively, 5% to 50% by mass; alternatively, 7.5% to 40% by mass; alternatively, 10% to 35% by mass relative to the overall mass of the zeolite extrudate. The composition of the binder may include, without limitation, Boehmite, alumina, silica doped alumina, titania doped alumina, lanthanum doped alumina, or a combination thereof. Alternatively, the composition is selected as one from the group consisting of Boehmite, alumina, silica doped alumina, titania doped alumina, and lanthanum doped alumina.

[0043] Preferably, the selection of the at least one additional acidic support is made such that the additional acidic support is different than the composition of the selected binder present in the zeolite extrudate. However, the use of an additional acidic support and a binder that have the same composition is within the scope of the present disclosure. When the additional acidic support and the binder have the same composition, the total amount of this additional acidic support and binder present in the zeolite extrudate is 85% to 15% by mass; alternatively, from 80% to 20% by mass; alternatively, 75% to 25% by mass; alternatively, 70% to 35% by mass relative to the overall mass of the zeolite extrudate.

[0044] Still referring to Fig. 2, an additional metal may be added 65 to the zeolite extrudate when necessary or desirable depending upon the intended application. This additional metal may include one or more metals selected from the group consisting of group VI metals and group VII to group X non-noble metals. These metals may include, without limitation, chromium (Cr), molybdenum (Mo), tungsten (W), iron (Fe), cobalt (Co), and nickel (Ni). The amount of the additional metal(s) that may be added 65 to the zeolite extrudate comprises an amount that ranges from about 0.1 % to 7.5% by mass; alternatively, 0.2% to 5.0% by mass; alternatively, 0.5% to 3.5% by mass relative to the overall mass of the formed catalyst. As demonstrated in Fig. 2, the additional metal(s) may be added either to the powder mixture before 55 or after shaping 60 the powder mixture into a zeolite extrudate.

[0045] For the purpose of this disclosure, the terms "at least one" and "one or more of' an element are used interchangeably and may have the same meaning. These terms, which refer to the inclusion of a single element or a plurality of the elements, may also be represented by the suffix "(s)"at the end of the element. For example, "at least one metal", "one or more metals", and "metal(s)" may be used interchangeably and are intended to have the same meaning.

[0046] For the purpose of this disclosure the terms "about" and "substantially" are used herein with respect to measurable values and ranges due to expected variations known to those skilled in the art (e.g., limitations and variability in measurements).

[0047] For the purpose of this disclosure, the recitations of numerical ranges by endpoints include the endpoints and all numbers within that numerical range. For example, an amount ranging from 40% by mass to 60% by mass includes concentrations of 40% by mass, 60% by mass, and all concentrations there between (e.g., 40.1 %, 41 %, 45%, 50%, 52.5%, 55%, 59%, etc.).

[0048] The following specific examples are given to illustrate the sphere-like ZSM- 48 zeolites and the catalyst extrudate(s) that incorporate such zeolites formed according to the teachings of the present disclosure and the method of forming these materials, as well as the properties thereof and should not be construed to limit the scope of the disclosure. Those skilled-in-the-art, in light of the present disclosure, will appreciate that many changes can be made in the specific embodiments which are disclosed herein and still obtain alike or similar result without departing from or exceeding the spirit or scope of the disclosure. One skilled in the art will further understand that any properties reported herein represent properties that are routinely measured and can be obtained by multiple different methods. The methods described herein represent one such method and other methods may be utilized without exceeding the scope of the present disclosure.

[0049] Test Methodology - The specific surface area (SSA) exhibited by the ZSM- 48 zeolites and catalysts are measured according to conventional Brunauer-Emmett- Teller (BET) analysis methods using a TriStar Micromeritics Inc. analyzer or similar instrument.

[0050] The crystalline phase or framework structure of the ZSM-48 zeolites may be characterized by x-ray diffraction (XRD) data. However, the XRD measurement may be influenced by a variety of factors, such as the growth direction of the zeolite; the ratio of constituent elements; the presence of an adsorbed substance, defects, or the like; resulting in a deviation in the intensity ratio or positioning of each peak in the XRD spectrum. Therefore, a deviation of 10% or less; alternatively, 5% or less; alternatively, 1 % or less in the numerical value measured for each parameter of the framework structure for a zeolite is within expected tolerance

[0051] The particle size and associated size distribution may be measured for the ZSM-48 zeolites using any known conventional technique, including but not limited to,using a laser particle size analyzer or scanning electron microscopy (SEM). Similarly, the sphericity of the ZSM-48 zeolites may be obtained by measurements taken through the use of scanning electron microscopy (SEM).

[0052] The loose bulk density of the ZSM-48 zeolites may be obtained simply by filling a container of known volume with dried powder or particles until it overflows, leveling the top of particles with the top of the container, and then obtaining the ratio of the mass of particles to the container’s volume.

[0053] The chemical composition of the ZSM-48 may be measured by inductively coupled plasma mass spectrometry (ICP-MS) or the like.

[0054] Example I - A Sphere-like ZSM-48 Zeolite Prepared with Dimethyl Carbonate (DMC) as Morphology Modifier.

[0055] In a 2 liter stainless steel autoclave a total of 7.04 grams of NaAIOs and 39.07 grams NaOH was dissolved in 882.27 grams of deionized (DI) water, Then 55.96 grams of hexamethonium bromide (HMBr, 50.2%) solution was added under stirring conditions. This was followed by slowly adding 798.95 grams of colloidal silica (Ludox® HS-30, W.R. Grace & Co.). Finally, 0.25 grams of beta structured (BEA) zeolites were added as seeds (0.1 % of SiO2 in gel) along with 16.71 grams of dimethyl carbonate (DMC) in the gel. The mixing was continued for an additional 30 minutes. The resulting gel has a molar ratio SiC>2 : HMBr : DMC : AI2O2 : Na2O : H2O of 1.0 : 0.019 : 0.045 : 0.00909 : 0.14 : 20.0. The gel was heated at 160°C for 36 hours with stirring. The collected product was washed with DI water by filtration and then dried at 120°C in an oven.

[0056] Referring now to Fig.’s 4A & 4B, the measured x-ray diffraction (XRD) pattern (Fig. 4A) for the powder 100 collected and dried in this Example I shows 2-theta peaks that correspond to the 2-theta peaks (Fig. 4B) exhibited by the structure or framework of a conventional ZSM-48 zeolite 200. The corresponding 2-theta peaks are labeled or identified within each figure with an asterisk (*). The measured XRD pattern for the ZSM-48 zeolites formed in this Example I further demonstrates that the ZSM-48 zeolites as collected are substantially free of any other type of crystalline zeolite phase or structure

[0057] The collected ZSM-48 zeolites are found to exhibit a morphology that is sphere-like with a particle size being in the range of 0.2 micrometers (pm) to 1 pm as demonstrated from scanning electron micrograph provided in Fig 5A. The particlesconsist of a primary crystal size that is less than 100 nanometers (nm). Further particle size analysis showed the occurrence of particle agglomeration resulting in a distribution ranging from 0.2 pm to 6.7 pm with an average Dso particle size of 1 .5 pm.

[0058] The collected powder was calcined at 595°C for 5 hours then ion exchanged with a concentration of 1 gram of ZSM-48 zeolite in 10 ml of 2N NH4HCO3 solution at room temperature for 2 hours. The ammonia form of the ZSM-48 zeolite was obtained by collecting the powder by filtration, Deionized (DI) water was used to wash the collected powder followed by oven drying at 125°C.

[0059] The BET specific surface area exhibited by the ammonia form of the ZSM-48 zeolites obtained in this Example I is 231 m2 / g with a pore volume of 0.21 cm3 / g and a pore diameter of 3.57 nm. The loose bulk density measured for the ammonia form of the ZSM-48 zeolites was found to be 0.23 g / cm3as measured by comparing the weight of the zeolites that completely fill a cylinder having a known volume.

[0060] Referring once again to Fig. 5A, the sphericity of the ZSM-48 zeolites was determined to be great than 0.80. The sphericity is determined as an average of measurements taken on at least 30 different particles that are randomly selected. Thus, the morphology of the ZSM-48 zeolite 100 formed and collected in this Example I is shown in the scanning electron micrograph (SEM) to comprise, consist of, or consist essentially of sphere-like 105 particles.

[0061] ICP analysis determined that the silica to alumina ratio (SAR) exhibited by the ZSM-48 zeolites formed in this Example I was 85. The amount of Na2O was determined to be less than 100 ppm with the loss on ignition (LOI) at 1 ,000°C being 5.6%.

[0062] This example demonstrates that the method according to the present disclosure provides an economical process for the preparation of ZSM-48 zeolites that exhibit a sphere-like morphology exemplified by a high sphericity and / or high loose bulk density.

[0063] Conventional ZSM-48 zeolite synthesis

[0064] Conventional ZSM-48 zeolites were prepared according to the procedure set forth in Example 1 of U.S. Patent No. 7,482,300, the entire content of which is hereby incorporated in its entirety by reference.

[0065] A mixture gel was prepared by mixing together water, hexamethonium chloride, precipitated silica powder (Hi-Sil 233, PPG), sodium aluminate, and sodiumhydroxide. This mixture gel had molar ratio of SiO2 : HMCI : AI2O2 : Na2O : H2O = 1 .0 : 0.023 : 0.00943 : 0.085 : 20.15. In a 2 liter autoclave, the mixture gel was heated at 160°C for 48 hours with stirring. The product was filtered, washed with deionized (DI) water, and dried in oven at 120°C.

[0066] The XRD pattern (Fig. 4B) of the as synthesized material showed the typical pure phase of ZSM-48 topology. The SEM (Fig. 5B) of the as-synthesized material shows that the material was composed of agglomerates of crystals with mixed morphologies (needle-like and irregularly shaped crystals). The particle size distribution of the agglomerated particles is from 0.2 pm to 17.38 pm with an average D50 particle size of 4.76 pm.

[0067] The ammonia form of the conventional ZSM-48 zeolite was obtained using the same procedures as used in Example I. The BET specific surface area exhibited by the ammonia form of the conventional ZSM-48 zeolites formed is 209 m2 / g with a pore volume of 0.40 cm3 / g and a pore diameter of 7.62 nm. The loose bulk density measured for the ammonia form of the conventional ZSM-48 zeolites was found to be 0.13 g / cm3. ICP analysis determined that the silica to alumina ratio (SAR) for the conventional ZSM-48 zeolites was 97 and the amount of Na2<3 to be less than 100 ppm with a loss on ignition (LOI) at 1 ,000°C of 7.4%.

[0068] Referring once again to Fig. 5B, the morphology of conventional ZSM-48 zeolites 110 is shown in the scanning electron micrograph (SEM) to comprise, consist of, or consist essentially of needle-like or rod-like 115 particles having an elongated structure or framework, wherein the values for both sphericity and loose bulk density were found to be substantially outside the limits set forth for the ZSM-48 zeolites formed according to the present disclosure.

[0069] Conventional preparation methods provide for the preparation of ZSM-48 zeolites that exhibit needle-like or rod-like morphology exhibiting non-sphericity and a low loose bulk density.

[0070] Example II - A Sphere-like ZSM-48 Zeolite Prepared Without Seeds

[0071] In a 2 liter stainless steel autoclave a total of 7.04 grams of NaAIC>2 and 35.78 grams of NaOH was dissolved in 878.62 grams of deionized (DI) water, Then, 64.80 grams of HMBr solution (50.2%) under stirring was added. Finally, 798.95 grams of colloidal silica (HS-30) and 16.71 grams of dimethyl carbonate (DMC) was slowly added into the gel. The gel was continued to be mixed for an additional 30 minutes. The resulting gel has a molar ratio of SiC>2 : HMBr : DMC : AI2O2 : Na2O : H2O equalto 1 .0 : 0.022 : 0.045 : 0.00909 : 0.13 : 20.0. The gel was heated at 160°C for 48 hours under stirring. The collected product was washed with deionized (DI) water by filtration and then dried at 120 °C in an oven.

[0072] The XRD pattern (see Fig. 4C) of the as synthesized material exhibits the typical pure phase of ZSM-48 topology. The SEM (see Fig. 5C) of the as-synthesized material 100 demonstrates that the material is composed of sphere-like agglomerates of small crystals less than 200 nm. These sphere-like agglomerates had a particle size < 1 .5 pm. Further particle size analysis showed a particle size distribution ranging from 1.32 pm - 11.6 pm with an average particle size Dso of 3.98 pm due to further clustering of the sphere-like agglomerates.

[0073] The ammonia form of the ZSM-48 zeolite was obtained using the same procedures as set forth in Example I. The BET specific surface area exhibited by the ammonia form of the ZSM-48 zeolites formed in this Example II is 201 m2 / g with a pore volume of 0.24 cm3 / g and a pore diameter of 4.9 nm. The loose bulk density measured for the ammonia form of the ZSM-48 zeolites was found to be 0.22 g / cm3. ICP analysis showed the formed ZSM-48 zeolites to have a silica to alumina ratio (SAR) of 89 and an amount of Na2O that was less than 100 ppm with a loss on ignition (LOI) at 1 ,000°C of 5.6%.

[0074] Referring once again to Fig. 5C, the sphericity of the ZSM-48 zeolites was determined to be greater than 0.90. The sphericity is determined as an average of measurements taken on at least 30 different particles that are randomly selected. Thus, the morphology of the ZSM-48 zeolite 100 formed and collected in this Example II is shown in the scanning electron micrograph (SEM) to comprise, consist of, or consist essentially of sphere-like 105 particles.

[0075] This Example II further demonstrates that the method according to the present disclosure provides an economical process for the preparation of ZSM-48 zeolites that exhibit a sphere-like morphology exemplified by a high sphericity and / or high loose bulk density.

[0076] Example III - Catalyst Formed as an Extrudate

[0077] A zeolite extrudate catalyst is prepared by first dry mixing 750 grams of ZSM- 48 in ammonium form prepared according to Examples I or II with 100 grams of a Boehmite as binder and another 150 grams of Boehmite as another acidic support. The Boehmite utilized has a surface area in the range of 200-300 m2 / g, a pore volume of 0.4 - 1 .0 cm3 / g and a dispersibility index of 20% - 40%. The dry powders are mixedfor 15 minutes and then impregnated with 400-600 grams of water and 5-40 grams of nitric acid with mixing for an additional 45 minutes. The resulting mixture is then pushed through an extruder followed by oven drying at 120°C for 4 hours and calcination at 550°C for 3 hours to form a zeolite extrudate. Thus, this zeolite extrudate contains 75% ZSM-48 zeolite, 10% binder, and 15% of another acidic support by mass. Since the binder and the other acidic support material in this Example III are both Boehmite, the total amount of the binder and the other acidic support represents 25% by mass relative to the mass of the zeolite extrudate.

[0078] The calcined zeolite extrudate is then impregnated with 5% by weight of nickel oxide relative to the weight of the overall catalyst. This is accomplished by dispersing 1 kg of the calcined zeolite extrudate in 500 grams of deionized (DI) water containing 50 grams of nickel oxide in the form of nickel nitrate. The catalyst is then dried at 120°C for 4 hours and calcined at 550°C for 3 hours.

[0079] The ZSN-48 zeolite was found to be extrudable in any desired form, including, without limitation, a cylinder, a trilobe, a quadrilobe, and a wagon wheel. The extruded zeolite with the impregnated transition metal was found to provide adequate performance in dewaxing and / or isomerization applications.

[0080] Within this specification, embodiments have been described in a way that enables a clear and concise specification to be written, but it is intended and will be appreciated that embodiments may be variously combined or separated without parting from the invention. For example, it will be appreciated that all preferred features described herein are applicable to all aspects of the invention described herein.

[0081] The foregoing description of various forms of the invention has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise forms disclosed. Numerous modifications or variations are possible in light of the above teachings. The forms discussed were chosen and described to provide the best illustration of the principles of the invention and its practical application to thereby enable one of ordinary skill in the art to utilize the invention in various forms and with various modifications as are suited to the particular use contemplated. All such modifications and variations are within the scope of the invention as determined by the appended claims when interpreted in accordance with the breadth to which they are fairly, legally, and equitably entitled.

Claims

CLAIMS1. A method of manufacturing a sphere-like ZSM-48 zeolite, the method comprising a hydrothermal process including the steps of: providing a source of alumina; providing a source of silica; providing an organic structure directional agent (OSDA); providing a mineralizing agent; mixing the sources of alumina, silica, OSDA, and mineralizing agent together in water to form an aqueous mixture; combining a morphology modifier and optionally a zeolite seed with the aqueous mixture to form a gel composition; subjecting the gel composition to the hydrothermal process in order for the ZSM-48 zeolite to crystallize, thereby, forming a crystalline precipitate and a mother liquid; and separating the crystalline precipitate from the mother liquid to obtain the ZSM- 48 zeolite having a silica to alumina ratio (SAR) that is in the range of 50 to 150; wherein the ZSM-48 zeolite has a sphere-like morphology defined by one or more of the following: a loose bulk density of > 0.15 g / cm3and a sphericity of > 0.5.

2. The method according to claim 1 , wherein the organic structure directional agent (OSDA) is hexamethonium bromide (HMBr), hexamethonium chloride (HMCI), or a combination thereof.

3. The method according to any of claims 1 or 2, wherein the mineralizing agent is sodium hydroxide (NaOH), potassium hydroxide (KOH), or a combination thereof.

4. The method according to any of claims 1 to 3, wherein the morphology modifier is dimethyl carbonate (DMC), sodium dodecyl sulfate (SDS), or a combination thereof.

5. The method according to any of claims 1 to 4, wherein the alumina source comprises one or more of aluminum hydroxide, sodium aluminate, and aluminum sulfate.

6. The method according to any of claims 1 to 5, wherein the silica source comprises at least one of colloidal silica, sodium silicate, and tetraethyl orthosilicate (TEOS).

7. The method according to any of claims 1 to 6, wherein the method includes the presence of the zeolite seed; the zeolite seed comprising one or more of a beta zeolite, a ZSM-48 zeolite, or another low framework density zeolite; wherein the zeolite seed is present in an amount ranging from > 0.0% to about 5.0%.

8. The method according to any of claims 1 to 7, wherein the gel composition comprises the following molar ratios:SiCk / AkOs 70 - 200M2O / SiO2 0.05 - 0.20OSDA / SiO20.01 - 0.200H2O / SiO210 - 50Modifier / SiC>2 0.001 - 0.100.

9. The method according to any of claims 1 to 8, wherein the hydrothermal process comprises subjecting the gel composition to a temperature that is in the range of 135°C to 200°C for a period of 1 to 3 days.

10. The method according to claim 9, wherein the temperature is in the range of 150°C to 180°C.

11. The method according to any of claims 1 to 10, wherein the silica to alumina ratio (SAR) is in the range of 70 to 120.

12. The method according to any of claims 1 to 11 , wherein the ZSM-48 zeolite comprises particle sizes that range between 0.5 pm to 10 pm as measured via scanning electron microscopy (SEM).

13. The method according to any of claims 1 to 12, wherein the sphere-like morphology of the ZSM-48 zeolite is defined by at least one of the following: a loose bulk density of > 0.20 g / cm3and a sphericity of > 0.8.

14. The method according to any of claims 1 to 13, wherein the ZSM-48 zeolite comprises a loose bulk density that is greater than 0.15 g / cm3; alternatively, the loose bulk density is greater than 0.20 g / cm3.

15. The method according to any of claims 1 to 14, wherein the ZSM-48 zeolite comprises a specific surface area that is greater than 200 m2 / g; alternatively, greater than 300 m2 / g, as determined according to Brunauer-Emmett-Teller (BET) analysis.

16. A method of forming a catalyst for de-waxing or isomerization, the method comprising the steps of: forming a sphere-like ZSM-48 zeolite according to any of claims 1 to 15; combining the ZSM-48 zeolite with a binder, and at least one other acidic support to form a powder mixture; shaping the powder mixture into an extrudate to form the catalyst.

17. The method according to claim 16, wherein the method further comprises the step of adding to the extrudate an additional metal selected as one or more from the group consisting of group VI metals and group VIII to group X non-noble metals; wherein the additional metal is present in an amount that ranges from 0.2% to 5.0% by mass relative to the overall mass of the catalyst.

18. The method according to any of claims 16 or 17, wherein the additional metal is added either before or after the shaping of the powder mixture into the extrudate.

19. The method according to any of claims 16 to 18, wherein the extrudate comprises the shape of a cylinder, a trilobe, a quadrilobe or a wagon wheel having a diameter in the range of 2 mm to 6 mm.1720. The method according to any of claims 16 to 19, wherein the ZSM-48 zeolite is present in an amount that ranges from 20% to about 75% by mass relative to the overall mass of the extrudate.21 . The method according to any of claims 16 to 20, wherein the binder is selected from the group consisting of clay, colloidal silica, Boehmite, gamma alumina, silica doped alumina, or a combination thereof; wherein the binder is present in an amount that ranges from 5% to 25% by mass relative to the overall mass of the extrudate.

22. The method according to any of claims 16 to 21 , wherein the at least one other acidic support is selected from the group consisting of Boehmite, alumina, silica-doped alumina, titania-doped alumina, lanthanum-doped alumina, and a combination thereof; the at least one other acidic support being selected so that it is different than the binder; wherein the at least one other acidic support is present in an amount that ranges from 5% to 40% by mass relative to the overall mass of the extrudate.

23. The method according to any of claims 16 to 22, wherein the binder and the at least one other acidic support have the same composition; such that the amount of the binder and the other acidic support together represent wherein the binder and the other acidic support together represent a total of 80% to 25% by mass relative to the overall mass of the extrudate.

24. A catalyst for de-waxing or isomerization formed by the method according to any of claims 16 to 23.

25. A sphere-like ZSM-48 zeolite formed by the method according to any of claims 1 to 15.18

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