Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
  • B01J37/0009—Use of binding agents; Moulding; Pressing; Powdering; Granulating; Addition of materials ameliorating the mechanical properties of the product catalyst
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J29/00—Catalysts comprising molecular sieves
  • B01J29/04—Catalysts comprising molecular sieves having base-exchange properties, e.g. crystalline zeolites
  • B01J29/06—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof
  • B01J29/08—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof of the faujasite type, e.g. type X or Y
  • B01J29/084—Y-type faujasite
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J29/00—Catalysts comprising molecular sieves
  • B01J29/04—Catalysts comprising molecular sieves having base-exchange properties, e.g. crystalline zeolites
  • B01J29/06—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof
  • B01J29/70—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof of types characterised by their specific structure not provided for in groups B01J29/08 - B01J29/65
  • B01J29/7007—Zeolite Beta

Definitions

• This invention relates to a method for preparing a mechanically stable zeolite catalyst composition possessing a refractory oxide binder of low acidity, e.g., a silica binder.
• zeolite designates the class of porous crystalline silicates, which contain silicon and oxygen atoms as the major components.
• Other framework components can be present in minor amount, usually less than about 14 mole ., and preferably less than 4.. These components include aluminum,, gallium, iron, boron, etc., and combinations thereof.
• the crystalline aluminosilicates constitute an especially well known type of zeolite.
• aluminosilicate zeolites have long been used as catalysts for a wide variety of organic conversion processes.
• aluminosilicate zeolites are incorporated with a matrix, or binder, material in order to impart mechanical stability thereto.
• matrix materials have included alumina and/or clays since these materials are fairly easy to extrude and provide extrudates of good physical strength.
• the method comprises mixing silica-rich solids, preferably a mixture of silica with a zeolite such as ZSM-4 (Omega), ZSM-5, ZSM-11, ZSM-12, ZSM-23, ZSM-35, ZSM-38, ZSM-48, Beta, X, Y, L, ferrierite, mordenite, dachiardite, clinoptilolite, offretite, erionite, gmelinite or chabazite with water and an alkali metal base such as sodium hydroxide or a basic salt such as an alkali-metal carbonate, borate, phosphate or silicate as an extrusion aid followed by mulling, extruding and subsequently drying the extrudate.
• a zeolite such as ZSM-4 (Omega), ZSM-5, ZSM-11, ZSM-12, ZSM-23, ZSM-35, ZSM-38, ZSM-48, Beta, X, Y, L, ferrierite
• Silica-bound zeolite catalysts prepared in accordance with the method described in U.S. Patent No. 4,582,815 are indicated to be useful in hydrocarbon conversions such as hydrocracking, isomerization, hydrogenation, dehydrogenation, polymerization, reforming, catalytic cracking and catalytic hydrocracking.
• a low acidity refractory oxide-bound zeolite possessing excellent mechanical stability and low binder acidity, making it especially useful as a catalyst for certain kinds of hydrocarbon conversions can be prepared by a method which comprises: a) providing a substantially homogeneous mixture of zeolite, water and a low acidity refractory oxide binder containing at least an extrusion-facilitating amount of said binder in a colloidal state to provide an extrudable mass, said mixture being substantially free of added alkali metal base and/or basic salt; b) extruding the extrudable mass resulting from step
• step (a) drying the extrudate resulting from step (b); and d) calcining the dried extrudate resulting from step
• the calcined extrudate can be subjected to other operations such as base exchange, dealumination, steaming and impregnating with catalytically active metal(s), the details of which are well known in the art.
• low acidity refractory oxide binders such as silica do not interact with zeolites to any appreciable extent. Consequently, zeolites can be bound with low acidity refractory oxides in accordance with the method of this invention without increasing the zeolite's intrinsic activity as might occur with an alumina binder.
• the use of low-acidity refractory oxide-bound zeolites having lower levels of inherent activity than their alumina-bound counterparts can result in lower coke production and significant increases in cycle length.
• the zeolite's intrinsic catalytic activity may actually be decreased by binding the zeolite with low acidity refractory oxides, such as silica.. More particularly, zeolite activity may be reduced by binding zeolites such as ZSM-5, Y, Beta, etc. with low acidity refractory oxides such as Si_ 2 and Ti0 2 .
• this reduction in activity is a result of a chemical reaction of the binder with the zeolite, whereby high acidity oxides such as alumina in the zeolite framework become replaced by low acidity refractory oxides from the binder.
• zeolites with a silica to alumina molar ratio of 70 or less may become enriched with framework silicon content by binding the zeolite with silica and treating the mixture at elevated temperatures.
• Zeolites treated in this manner may exhibit lower exchange capacities, hexane cracking (e.g., as measured by alpha value) and toluene disproportionation activities, and shifts in x-ray diffraction patterns.
• a silica-bound, low sodium, framework dealuminated zeolite Y e.g., ultrastable Y (USY) zeolite
• USY ultrastable Y
• the low acidity refractory oxide-bound zeolite catalysts of the present invention are capable of maintaining their structural integrity in low pH solutions, the zeolite dispersed in such, a binder can be treated with an acid solution to effect dealumination. This effectively results in a
• the method of this invention is not limited to any ' particular zeolite and in general may be employed with all metallosilicates, particularly the aluminosilicates whether or
• Typical zeolites include ZSM-4 (Omega), ZSM-5; ZSM-11, ZSM-12, ZSM-20, ZSM-23, ZSM-35, ZSM-48, ZSM-50, Beta, X, Y and L as well as ferrierite, mordenite, dachiardite, clinoptilollte, offretite, erionite, gmelinite and chabazite.
• 30 zeolites utilized herein can be replaced by a wide variety of other cations employing techniques well known in the art. Typical replacing cations including hydronium, ammonium, alkyl ammonium and metal cations. Suitable metal cations include metals such as rare earth metals, as well as metals of Groups IIA and B of the Periodic Table, e.g., zinc, and Group VIII of the Periodic Table, e.g., platinum and palladium.
• Typical ion-exchange techniques call for contacting the selected zeolite with a salt of the desired replacing cation.
• a wide variety of salts can be employed, particular preference is given to chlorides, nitrates and sulfates.
• Representative ion-exchange techniques are disclosed in a wide variety of patents including U.S. Patent Nos. 3,140,249; 3,140,251; and 3,140,253.
• the zeolite is then preferably washed with water and dried at a temperature of 65-315°C (150-600°F) and thereafter calcined in air, or other inert gas, at a temperature of 260-815°C (500-1500°F) for 1 to 48 hours or more.
• Catalysts of improved selectivity and other beneficial properties can be obtained by subjecting the zeolite to treatment with steam at elevated temperatures ranging from 260 to 650°C (500 to 1200°F) and preferably from 400 to 540°C (750 to 1000°F).
• the treatment can be accomplished in an atmosphere of 100% steam or in an atmosphere consisting of steam or ammonia and some other gas which is essentially inert to the zeolites.
• a similar treatment can be accomplished at lower temperatures and elevated pressure, e.g., from 180 to 370°C (350° to about 700°F) at from 1000-20000 kPa (10 to 200 atmospheres).
• the zeolite can be treated with reagents prior to steaming and with organics still contained from synthesis to remove alumina from the outside surface, or calcined in air or inert atmosphere to remove the organics and then ion exchanged to the ammonium form or other desired metal exchanged form.
• Processes for dealuminizing Y are well known in the art, i.e., see Rabo, Zeolite Chemistry and Catalysis, ACS Monograph 171(1976) Chapter 4.
• the binder material used herein can be selected from among any of the low acidity refractory oxides of metals of Groups IVA and IVB of the Periodic Table of the Elements. Particularly useful are the oxides of silicon, germanium, titanium and zirconium with silica being especially preferred. Combinations of such oxides with other oxides are also useful provided that at least about 40 weight percent, and preferably at least 50 weight percent, of the total oxide is one or a combination of the aforesaid Group IVA and/or Group IVB metal oxides.
• mixtures of oxides which can be used to provide the binder material herein include silica-alumina, silica-magnesia, silica-zirconia, silica-thoria, silica-beryllia, silica-titania, titania-zirconia, silica-alumina-thoria, silica-alumina- zirconia, silica-alumina-magnesia and silica-magnesia-zirconia.
• the low acidity refractory oxide contains at least an extrusion-facilitating amount of the oxide in colloidal form, preferably with water as the dispersant.
• at least part of the low acidity refractory oxide is added in dry particulate form, e.g. amorphous precipitated silica, so as to control the moisture content of the binder/zeolite/water mixture at a level to ensure satisfactory extrusion.
• the moisture content of the mixture does not exceed 50%, and preferably is at least 40%, by weight. No alkali metal base or basic salt is added to the mixture.
• the colloidal Group IVA and or Group IVB metal oxide component of the binder can represent anywhere from 1 to 90 weight percent or more of the total binder.
• amounts of colloidal silica ranging from 2 to 60 weight percent, preferably 5 to 50 weight percent, of the total binder generally provide entirely acceptable results.
• the relative proportions of zeolite and low acidity refractory oxide binder can vary widely, with the zeolite content ranging from between 1 to 99 weight percent, and more usually in the range of from 4 to 90 weight percent, of the total extrudate (dry basis).
• Extrudates of 1/16 inch (1.6mm) obtained in accordance with this invention typically have a crush strength of from 5 to 24 pounds (2 - 11kg) when the crushing force is applied over a 1/8 inch (3.2mm) length. This is equivalent to a crush strength range of 40 to 192 lb/linear inch (700 - 3430kg/m).
• the low acidity refractory oxide-bound extrudates of this invention are also characterized by a high porosity, i.e., between 0.43 to l.cc/gram (measured by mercury porosimeter and helium absorption) .
• the extrudates of this invention can find utility in a wide variety of processes which are both catalytic and noncatalytic. Quite obviously, the materials can be used as sorbents. Additionally, the materials can be used as catalysts for a wide variety of organic conversions. Moreover, since a low acidity refractory oxide, such as silica, has low catalytic activity, the incorporation of a zeolite in the silica can lead to some unusual catalytic effects.
• the low acidity refractory oxide can also be used as a support for a catalytic material, e.g., a hydrogenation component such as platinum, palladium, cobalt, molybdenum, iron, tungsten, nickel or mixtures of the same.
• the catalytic metals in the form of their oxides or salts can also be added to the low acidity refractory oxide during the mulling step with pH adjustment, if necessary, to stabilize the colloidal oxide component of the mixture.
• the low acidity refractory oxide-bound zeolite extrudates of the invention find utility in catalytic cracking, typically under conditions including a temperature of at least 315°C (600°F), generally 400.-600°C (750°-1100°F), and pressures between 100 and 1500 kPa (atmospheric and 200 psig).
• the cracking can be conducted in the presence of hydrogen, preferably with the hydrogen partial pressure being no greater than 7000 kPa.
• This example illustrates the preparation of an alumina-bound USY catalyst to provide a basis for comparison with silica-bound USY catalysts prepared in accordance with the method of this invention (Examples 2-6).
• Examples 2-6 On a dry basis, 65 weight parts of USY zeolite (Z-14US, W.R. Grace) were intimately admixed with 35 weight parts finely divided alpha alumina monohydrate (Kaiser SA) and an extrudable mass was obtained by mulling. The moisture content of the mix was adjusted to 46-48 weight percent by addition of deionized water. After additional mulling, the resulting paste was extruded using a 2" (5cm) Bonnot extruder to yield 1/16" (1.6mm) diameter extrudates.
• extrudates were subsequently dried at 121°C (250°F) for 18 hours in air and then calcined at 540°C (1000°F) for 3 hours in air flowing at 3 or 5 v/v/min. Heating rates of 2 or 3°C/min (3 or 5°F/min) were used. Examples 2-6
• the extrudate was washed and dried at 121°C (250°F) in air and subsequently calcined at 540°C (1000°F) for 3 hours in dry flowing air. This procedure was repeated three times so that the acidity of the catalyst (as measured by the alpha test) increased to a level of 250 to 300 and the sodium content was reduced from 1.8-1.9 to 0.1-0.2 wt %.
• the calcinations were performed in a relatively anhydrous environment to preclude any significant steaming of the catalyst.
• zeolite beta on a dry basis in the form of a powder was mulled with 35 wt parts of combined amorphous precipitated silica (HiSil 233 EP) and colloidal silica to produce a homogeneous mix. To facilitate admixture, the moisture content of the mix was adjusted to 45-49 weight percent by adjusting the amount of deionized water added. Two different amounts of colloidal Si0 2 were added to obtain extrudable mixes while maintaining a 65/35 zeolite/binder weight ratio. The resulting mixes were extruded to yield 1.6mm (1/16") diameter extrudates.
• HiSil 233 EP amorphous precipitated silica
• colloidal silica colloidal silica
• extrudates were dried at 121°C (250°F) for 18 hours and were subsequently calcined at 540°C (1000°F) for 3 hours in nitrogen flowing at 3 or 5 v/v/min. This was followed by a 3 hour calcination at 1000°F (540°C) in air flowing at 3 or 5 v/v/min.
• each extrudate was exchanged twice at room temperature for 1 hour with a 5 ml/g circulating IN ammonium nitrate solution. After washing the extrudate was then calcined at 540°C (1000°F) for 3 hours in air flowing at 3 or 5 v/v/min.
• silica-bound ZSM-5 extrudates (Examples 11 and 12) were prepared substantially as described in Examples 8 and 9.
• the physical properties of the silica-bound ZSM-5 extrudates and those of a commercial alumina-bound ZSM-5 extrudate (Example 10) are set forth in Table 3 as follows:
• silica-bound catalysts prepared by the extrusion method of this invention retain their structural integrity upon calcination and ammonium exchange.
• An important advantage of silica-bound zeolite catalysts is that the extrudates can be acid treated without losing their structural integrity.
• the silica-bound USY catalyst of Example 3 was steamed for 10 hours at 540°C (1000°F) to reduce the alpha activity from 255 to 50-60 and to reduce the unit cell size from 24.52 to 24.35 Angstroms.
• the steamed extrudate (Example 13) was then treated for 4 hours in a IN HN03 solution at 55oC or 85oC (Examples 14-17).
• a sodium exchanged zeolite Y (NaY) was extruded with silica in a 65/35 zeolite binder ratio.
• This extrudate was prepared by mixing, on a dry basis, 65 weight parts of NaY with 17.5 weight parts amorphous precipitated silica (HiSil 233 EP) and 17.5 weight parts of colloidal silica (HS-30). After mulling and water addition as appropriate, the resulting homogenous mixture paste was extruded to 1/16" diameter extrudate. The extrudate was dried at 121°C. 1 gram of this catalyst was calcined at 538°C for four hours under high nitrogen purge such that in-situ steaming of the material was avoided. The calcined silica bound catalyst was analyzed by x-ray diffraction along with the uncalcined silica bound catalyst.
• X-ray diffraction data was collected at the Brookhaven National Laboratory, National Synchrotron Light Source on the - X13A powder diffractometer.
• the diffractbmeter employs parallel beam geometry with a Ge(lll) incident beam monochromater and a Ge(220) analyzer crystal. Data was obtained with a 2-theta step scan of 0.01 degrees, 2 second count times per step, a theta scan of 2 degrees per step, and an x-ray wavelength of 1.3208 Angstroms.
• the 2-theta zero and x-ray wavelength were calibrated with a National Bureau of Standards silicon metal standard.
• D-spacings were obtained ' from the measured data with a second derivative peak search algorithm.
• the lattice parameters were refined with a standard least-squares refinement program.
• a zeolite beta/silica mix was prepared with a 65/35 weight ratio as in examples 8 and 9 but using only colloidal silica as the low acidity, refractory oxide source.
• zeolite beta crystals ash content 75.5%
• colloidal silica Lidox HS-30
• Example 19 The process of Example 19 was repeated but with ratio of the zeolite beta (ash content 75.5%) to colloidal silica (ash content 30%) increased to 82.5/17.5 to produce mixtures in which the moisture content was at a level suitable for extrusion.
• ratio of the zeolite beta (ash content 75.5%) to colloidal silica (ash content 30%) increased to 82.5/17.5 to produce mixtures in which the moisture content was at a level suitable for extrusion.
• Table 5 Table 5 Physical Properties of Silica-Bound Zeolite Beta

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