EP0393138A4

EP0393138A4 - Crystalline molecular sieve

Info

Publication number: EP0393138A4
Application number: EP19890901225
Authority: EP
Inventors: Cynthia Ting-Wah Chu; Eric Gerard Derouane; Michael Eugene Landis; Roland Von Ballmoos
Original assignee: Mobil Oil Corp
Current assignee: ExxonMobil Oil Corp
Priority date: 1987-12-21
Filing date: 1988-12-16
Publication date: 1992-01-02
Also published as: EP0393138A1; JPH03504372A; CA1329798C; NZ227383A; AU2924089A; DK150590A; DK150590D0; WO1989005775A1

Abstract

A synthetic crystalline molecular sieve composition comprises at least 70 % by weight of a crystalline material having the following X-ray diffraction lines:

Description

-1-

CRYSTALLINE MOLECULAR SIEVE

This invention relates to a synthetic crystalline^"molecular sieve composition and in particular to a composition containing a framework +3 valence element, e.g. aluminum, a framework +5 valence element, e.g. phosphorous, and preferably a framework +4 valence element, e.g. silicon.

Zeolitic materials, both natural and synthetic, have been demonstrated in the past to have catalytic properties for various types of hydrocarbon conversion. Certain zeolitic materials are ordered, porous crystalline aluminosilicates having a definite crystalline structure as determined by X-ray diffraction, within which there are cavities which may be interconnected by channels or pores. These cavities and pores are uniform in size within a specific zeolitic material. Since the dimensions of these pores are such as to accept for adsorption molecules of certain dimensions while rejecting those of larger dimensions, these materials have come to be known as "molecular sieves" and are utilized in a variety of ways, to take advantage of these properties.

Such molecular sieves, both natural and synthetic, include a wide variety of positive ion-containing crystalline aluminosilicates. These aluminosilicates can be described as rigid three-dimensional frameworks of SiO. and A10. in which the tetrahedra are cross-linked by the sharing of oxygen atoms whereby the ratio of the total aluminum and silicon atoms to oxygen atoms is 1:2. The electrovalence of the tetrahedra containing aluminum is balanced by the inclusion in the crystal of a cation, for example an alkali metal or an alkaline earth metal cation. This can be expressed wherein the ratio of aluminum to the number of various cations, such as Ca/2, Sr/2, Na, K or Li, is equal to unity. Che type of cation may be exchanged either entirely or partially with another type of cation utilizing ion exchange techniques in a conventional manner. By means of such cation exchange, it has been possible to vary the properties of a given aluminosilicate by suitable selection of the cation.

Prior art techniques have resulted in the formation of a great variety of synthetic zeolites. The zeolites have come to be designated by letter or other convenient symbols, as illustrated by zeolite A (U.S. Patent 2,882,243), zeolite X (U.S. Patent 2,882,244), zeolite Y (U.S. Patent 3,130,007), zeolite Z -5 (U.S. Patent 3,247,195), zeolite ZK-4 (U.S. Patent 3,314,752), zeolite ZSM-5 (U.S. Patent 3,702,886), zeolite ZSM-11 (U.S. Patent

3,709,979), zeolite ZSM-12 (U.S. Patent 3,832,449), zeolite ZSM-20 (U.S. Patent 3,972,983), zeolite ZSM-35 (U.S. Patent 4,016,245), zeolite ZSM-38 (U.S. Patent 4,046,859), and zeolite ZSM-23 (U.S. Patent 4,076,842). Aluminum phosphates are taught in, for example U.S.

Patents 4,310,440 and 4,385,994.

Silicoaluminophosphates of various structure are taught in U.S. Patent 4,440,871. U.S. Patent 4,363,748 describes a combination of silica and aluminu -calciu -cerium phosphate as a low acid activity catalyst for oxidative dehydrogenation. Great Eritain Patent 2,068,253 discloses a combination of silica and aluminum-calcium-tungsten phosphate as a low acid activity catalyst for oxidative dehydrogenation. U.S. Patent 4,228,036 teaches an alumina-aluminum phosphate-silica matrix as an amorphous body to be mixed with zeolite for use as cracking catalyst. U.S. Patent

3,213,035 teaches improving hardness of aluminosilicate catalysts by treatment with phosphoric acid. The catalysts are amorphous.

The present invention resides in a novel synthetic crystalline molecular sieve composition comprising at least 70% by weight of a crystalline material having the X-ray diffraction lines listed in Table 1A below: and more specifically the following X-ray diffraction lines:

Table IB

These X-ray diffraction data were collected with conventional X-ray systems, using copper K-alpha radiation. The positions of the peaks, expressed in degrees 2 theta, where theta is the Bragg angle, were determined by scanning 2 theta. The interplanar spacings, d, measured in Angstrom units (A), and the relative intensities of the lines, I/I_0> where I is one-hundredth of the intensity of the strongest line, including subtraction of the background, were derived. The relative intensities are given in terms of the symbols vs = very strong (75-1001), s = strong (50-74%), = medium (25-49%) and w = weak (0-24%). It should be understood that this X-ray diffraction pattern is characteristic of all the species of the present compositions. Ion exchange of cations with other ions results in a composition which reveals substantially the same X-ray diffraction pattern with some minor shifts in interplanar spacing and variation in relative intensity. Relative intensity of individual lines may ⁵ also vary relative the^" strongest line when the composition is chemically treated, such as by dilute acid treatment. Other variations can occur, depending on the composition of the particular sample, as well as its degree of thermal treatment. The relative intensities of the lines are also susceptible to changes by factors ° such as sorption of water, hydrocarbons or other components in the channel structure. F rther, the optics of the X-ray diffraction equipment can have significant effects on intensity, particularly in the low angle region. Intensities may also be affected by preferred crystallite orientation. In addition, the line at a d-spacing of 6.19 +_ 0.07A is believed to be a doublet at 6.21 +_ 0.05A and 6.17 + 0.05A but in many cases the doublet is difficult to resolve.

The X-ray diffraction lines in Tables 1A and IB identify a crystal framework topology exhibiting large pore windows of 0 18-membered ring size. The pores are at least 12 Angstroms, e.g. 12-13 Angstrom, in diameter.

The crystalline framework of the composition of this invention has the general chemical formula:

5 + (X0 ) :(Y0 ) :(Z0 ) 2 1-y 2 1-x 2 x+y wherein X is a +3 valence element, Y is a +5 valence element, Z is an optional +4 valence element, and x and y are each greater than -1 and less than +1, with anions and/or cations being present as 0 necessary for electrical neutrality. Preferably, the element Z is present and x and y satisfy the further relationships:

(1) if x is 0, then y is not 0,

(2) if y is 0, then x is not 0, and

(3) x + y is greater than 0.001 and less than 1. In the above composition, the +3 valence element x is preferably selected from aluminum, iron, chromium, vanadium, molybdenum, arsenic, antimony, manganese, gallium and boron; the +4 valence element Z is preferably selected from silicon, germanium and titanium; the .+5 valence element Y is preferably selected from phosphorous, arsenic, antimony and vanadium. Most preferably, X is aluminum, Y is phosphorus and Z is silicon.

In the composition above, depending on the values of x and y, the composition can be a cation exchange material with potential use as an acidic catalyst, or it can be an anion exchange material with potential use as a basic catalyst.

The composition of the present invention is prepared by providing a reaction mixture comprising sources of X oxide, Y oxide and Z oxide, water, an organic directing agent B, inorganic cations M and. anions N, the components of said reaction mixture having the following relationship:

(D)_a:(M₂0)_b:(X₂0₃)_c:(Z0₂)_d:(Y₂0₅)_e:(N)_g:(H₂0)_h

where a, b, c, d, e, f, g, and h are numbers satisfying the following relationships:

d/(d+2c+2e) is up to 0.2 (preferably 0.05 to 0.2) a/(d+2c+2e) is 0.2 to 0.4, and preferably the addition relationships: b/(c+d+e) is less than 2, c ^ e g/(c-κl+e) is less than 2, and h/(c+d+e) is from 3 to 150,

The initial pH of the reaction mixture should be 4-6. The mixture is heated with agitation to a temperature of 130 to 155°C and maintained at this temperature until crystals of oxide material are formed.

The pH is controlled during the reaction so that the final pH is 6-7 and the reaction to produce at least 70%, and preferably at least 80% of the composition of the invention (based on the weight of the total crystalline phase) is normally complete after 4-20 hours. The crystalline product is recovered by separating same from the reaction medium, such as by cooling the whole to room temperature, filtering and washing with water before drying.

In some cases it may be desirable to employ a two-phase reaction mixture, in which at least one of the X, Y and Z oxides is dissolved or dispersed in an organic solvent.

The above reaction mixture composition can be prepared from any suitable materials which supply the appropriate components. Useful sources of +3 valence element, e.g. aluminum, include any known form of oxide or hydroxide, organic or inorganic salt or compound. Useful sources of +4 valence element, e.g. silicon, include, any known form of dioxide or silicic acid, alkoxy- or other compounds of such element. Useful sources of +5 valence element, e.g. phosphorus, include, any known form of phosphorus acids or phosphorus oxides, phosphates and phosphites, and organic derivatives of such element.

The organic solvent is a Cr-C,₀ alcohol or any other liquid compound substantially immiscible with water.

The organic directing agent can be an organic mono- or dialkylamine, with alkyl being of 3 or 4 carbon atoms, or an onium compounds having the following formula:

R₄M⁺X~ or (R₃M⁺R'M⁺R₃)X₂

wherein R or R ¹ is alkyl of from 1 to 20 carbon atoms , or combinations thereof ; M is a tetra coordinate element (e.g . nitrogen, phosphorus , arsenic, antimony or bismuth) ; and X is an anion (e .g. fluoride , chloride , bromide , iodide, hydroxide , acetate , sulfate, carboxylate) . Particularly preferred directing agents include tetraethylammonium hydroxide , tetra propylammonium bromide or most preferably tetrapropylammonium hydroxide and dialkylamines wherein alkyl is butyl or most preferably propyl. In order to avoid the production of unwanted crystalline phases, the temperature must be carefully controlled within the 130 - 155°C range specified abaove. The preferred temperature within this range depends on the directing agent employed, so that with 5 dipropyla ine the preferred temperature is 135 - 155°C, most preferably about 150°C, whereas with tetrapropylammonium hydroxide the preferred temperature is 130 - 145°C, preferably about 135°C.

In its synthesized form the present composition will also contain occluded organic directing agent and water molecules, 1° entrapped during the synthesis and filling the icroporous voids. However, these can be removed by heating.

The original cations of the as-synthesized present composition can be replaced in accordance with techniques well known in the art, at least in part, by ion exchange with other cations. I⁵ Preferred replacing cations include metal ions, hydrogen ions, hydrogen precursor, e.g. ammonium, ions and mixtures thereof. Particularly preferred cations are those which render the composition catalytically active or control catalytic activity, especially for hydrocarbon conversion. These include hydrogen, rare

20 earth metal and metals of Groups IA, IIA, IIIA, IVA, IB, IIB, IIIB, IVB, VIB and VIII of the Periodic Table of the Elements.

A typical ion exchange technique would be to contact the synthetic present composition with a salt of the desired replacing cation or cations. Examples of such salts include the halides, e.g.

25 chlorides, nitrates and sulfates.

The crystalline composition of the present invention can be beneficially thermally treated, either before or after ion exchange. This thermal treatment is performed by heating the composition in an atmosphere such as air, nitrogen, hydrogen, steam, 0 etc., at a temperature of from 300°C to 1100°C, preferably from 350°C to 750°C, for from 1 minute to 20 hours. While subatmospheric or superatmospheric pressures may be used for this thermal treatment, atmospheric pressure is desired for reasons of convenience. It may be desirable to incorporate the new composition with another material, i.e. a matrix, resistant to the temperatures and other conditions employed in various organic conversion processes. Such materials include active and inactive material and synthetic or naturally occurring zeolites as well as inorganic materials such as clays, silica and/or metal oxides, e.g. alumina. The latter may be either naturally occurring or in the form of gelatinous precipitates or gels including mixtures of silica and metal oxides. Catalyst compositions containing the present composition will generally comprise from 1% to 90% by weight of the present composition and from 10% to 99% by weight of the matrix material. More preferably, such catalyst compositions will comprise from 2% to 80% by weight of the present composition and from 20% to 98% by weight of the matrix. Use of a material in conjunction with the new composition, i.e. combined therewith, which is active, tends to alter the conversion and/or selectivity of the overall catalyst in certain organic conversion processes. Inactive materials suitably serve as diluents to cont--ol the amount of conversion in a given process so that products can be obtained economically and orderly without employing other means for controlling the rate of reaction. These materials may be incorporated into naturally occurring clays, e.g. bentonite and kaolin, to improve the crush strength of the catalyst under commercial operating conditions. Said materials, i.e. clays, oxides, etc., function as binders for the catalyst. It may be desirable to provide a catalyst having good crush strength because in commercial use it is desirable to prevent the catalyst from breaking down into powder-like materials. These clay binders have been employed normally only for the purpose of improving the crush strength of the overall catalyst. Naturally occurring clays which can be composited with the new crystal include the montmorillonite and kaolin families which include the subbentonites, and the kaolins commonly known as Dixie, McNamee, Georgia and Florida clays or others in which the main mineral constituent is halloysite, kaolinite, dickite, nacrite, or anauxite. Such clays can be used in the raw state as originally mined or initially subjected to calcination, acid treatment or chemical modification.

In addition to the foregoing materials, the present composition can be composited with a porous matrix material such as aluminum phosphate, silica-alumina, silica-magnesia, silica-zirconia, silica-thoria, silica-beryllia, silica-titania as well as ternary compositions such as silica-alumina-thoria, silica-alu ina-zirconia silica-alumina-magnesia and silica-magnesia-zirconia. The relative proportions of finely divided crystalline material and inorganic oxide gel matrix vary widely, with the crystal content ranging from 1 to 90 percent by weight and more usually, particularly when the composite is prepared in the form of beads, in the range of 2 to 80 weight percent of the composite.

Employing a catalytically active form of the present composition as a catalyst component, said catalyst possibly containing additional hydrogenation components, reforming stocks can be reformed employing a temperature of 370°C to 540°C, a pressure of 100 psig to 1000 psig (791 to 6996 kPa), preferably from 200 psig to

700 psig (1480 to 4928 kPa), a liquid hourly space velocity is of 0.1 to 10, preferably 0.5 to 4, and a hydrogen to hydrocarbon mole ratio of 1 to 20, preferably 4 to 12.

A catalyst comprising the present composition can also be used for hydroisomerization of normal paraffins, when provided with a hydrogenation component, e.g. platinum. Such hydroisomerization is carried out at a temperature of 90°C to 375°C, preferably 145°C to 290°C, with a liquid hourly space velocity of 0.01 to 2, preferably 0.25 to 0.50, and with a hydrogen to hydrocarbon mole ratio of 1:1 to 5:1. Additionally, such a catalyst can be used for olefin or aromatic isomerization, employing a temperature of 200°C to 480°C. Such a catalyst can also be used for reducing the pour point of gas oils. This reaction is carried out at a liquid hourly space velocity of 10 to 30 and at a temperature of 425°C to 595°C.

Other reactions which can be accomplished employing a catalyst comprising the composition of this invention containing a metal, e.g. platinum, include hydrogenation-dehydrogenation reactions and desulfurization reactions, olefin polymerization (oligomerization) and other organic compound conversions, such as the conversion of alcohols (e.g. ethanol) or ethers (e.g. dimethylether) to hydrocarbons, and the alkylation of aromatics (e.g. benzene) in the presence of an alkylating agent (e.g. ethylene).

The invention will now be more particularly described with reference to the Examples and the accompanying drawings, in which:

Figure 1 shows the X-ray diffraction pattern of the as-synthesized Example 1 product;

Figure 2 shows the X-ray diffraction pattern of the calcined Example 1 product; and

Figure 3 shows the X-ray diffraction pattern of the as-synthesized Example 3 product; and

Figure 4 shows the X-ray diffraction pattern of the calcined Example 3 product.

EXAMPLE 1 A two-phase synthesis reaction mixture was prepared with the organic phase comprising lOg Si (OC₂H₅)₄ and 60g 1-hexanol, and the aqueous phase comprising 23g H,P0₄ (85%), 14g A1₂0₃, lOg di-n-propylamine (DPA) and 60g of H₂0. The reaction mixture as a whole had the following approximate composition:

Si/Si+A1+P = 0.1 DPA/Si+Al+P = 0.2 The reaction mixture had a starting pH of 5.5 and having been stirred without heating for 15 minutes, was heated at 50°C per hour to 150°C and maintained at that temperature for 24 hours while being stirred at 800 rpm until crystals of silicophosphoaluminate formed. The final pH was 7.

The crystalline product was separated from the reaction mixture by filtration, washed with toluene and ether and then dried. A sample of the product was then submitted for X-ray analysis and found to be a crystalline composition exhibiting the diffraction lines shown in Table 2A. The X-ray diffraction pattern of this sample is shown in Figure 1. This product, after calcination at 450°C in nitrogen and air for four hours each, was found to have the X-ray pattern shown in Table 2B and Figure 2.

Table 2A

*dif fraction lines identifying a crystal _.framework topology having pore windows formed by 18 tetrahedral members .

**diffraction lines of * plus additiosal intensity contribution from other crystalline phase.

*** doublet.

*diffraction lines identifying a crystal framework topology having pore windows formed by 18 tetrahedral members.

**diffraction lines of * plus additional intensity contribution from other crystalline phase.

*** doublet. Analysis of the X-ray data of the as-synthesized and calcined products showed the the crystalline phase contained in excess of 80% by weight of the crystalline material of the invention having the X-ray lines listed in Tables 1A and IB.

EXAMPLE 2 The process of Example 1 was repeated but with the reaction mixture being heated at 50°C/hour to 130°C, maintained at this temperature for 24 hours , heated to 200°C, and then maintained at this temperature for 24 hours . In this case, although the composition having the X-ray lines listed in Tables 1A and B was present, it constituted less than 70% by weight of the overall crystalline product .

Example 3

A mixture containing 38.3 g of 85% orthophosphoric acid (H_τP0₄) in 50 g water was mixed with 22.97 g hydrated aluminium oxide (Kaiser A1-0- . The mixture was heated to 80°C with stirring for 1/2 hour. To this mixture was added 108.8 g tetrapropylammonium hydroxide (TPAOF 25%). Crystallization in an autoclave was at 135°C at autogenous pressure for 16 hours. The solid product was filtered, washed and dried. Figure 3 shows the X-ray diffraction pattern of the as-synthesized material and Figure 4 shows that of the calcined material (calcined at 538°C in N_ for 2 hours). Tables 3 and 4 show X-ray powder diffraction data of the as-synthesized and calcined samples, respectively.

Analysis of the X-ray information indicated that the crystalline product of this example contained in excess of 90% by weight of a material having the X-ray lines of Tables 1A and IB. Table 3

Interplanar d-Spacings (A)

16.3 13.4 12.0 11.4

9.3

8.10

6.85

6.15

5 .97

5 .39

4.670

4.496

4.384

4.241

4.143

4.066

4.014

3.946

3.707

3.531

3.431

3.388

3.246

3.104

3.045

Table 4

Interplanar d-Spacings (A)

16.5 12.0 9.5 - 8.21 6^".17 5.47 4.729 4. 280 4.081 3.959 3.840 3.760 3.638 3.579 3.409 3.274 3.155 3.082 3.029

Claims

CLAIMS:

1. A synthetic crystalline molecular sieve composition comprising at least 70% by weight of a crystalline material having the X-ray diffraction lines in Table 1A by weight of the crystalline phase..

2. The composition of claim 1 wherein said material has the X-ray diffraction lines listed in Table IB.

3. The composition of claim 1 wherein the crystal framework of sad material has the following composition:

OTO₂);_„y :(Y0₂)J__χ :(Z0₂)_χ+y wherein X is a +3 valence element, Y is a +5 valence element, Z is a +4 valence element, and x and y are each greater than -1 and less than +1.

4. The composition of claim 4 wherein x and y satisfy the further relationships

(i) if x is 0, then y is not 0,

(ii) if y is 0, then x is not 0, and

(iii) x + y is greater than 0.001 and less than 1.

5. The composition of claim 3 or claim 4 wherein X is aluminum, Y is phosphorus and Z is silicon.

6. A method of producing the composition of claim 3 comprising the step of providing a reaction mixture comprising water, sources of oxides of the elements X, Y and Z, an organic directing agent D, inorganic cations M and anions N is the following molar relationship

(D)_a:C^0)_b:(X₂0₃)_c:(Z0_£)_d:(Y₂0₅)_e: (Solvent)_f:(N) :(F₂0)_h wherein a/(d+2c+2e) is up to 0.2 d/(d+2c+2e) is 0.2 to 0.4

and heating the mixture to a temperature of 130 - 155°C for 4 - 20 hours.

7. The method of claim 6 wherein the mixture obeys the following additional relationships:

a/(d+2c+2e) is 0.05 to 0.2, b/(c+d-*e) is less than 2, c e, g/(c+d+e) is less than 2, and h/(c+d+e) is from 3 to 150,

8. The method of claim 5 or claim 6 wherein the directing ag-.nt is dipropylamine and said temperature is 135 - 155°C.

9. The method of claim 5 or claim 6 wherein the directing agent is a tetrapropylammonium compound and said temperature is 130

- 145°C.

10. The method of claim 5 or claim 6 wherein the initial pH of said mixture is 4 - 6.

11. The method of claim 10 wherein the final pH of the mixture is 6-7.

12. The method of claim 5 or claim 6 wherein the mixture comprises an aqueous phase and an organic phase, at least one of said oxides being dispersed or dissolved in the. organic phase and the mixture being agitated to admix the phases during the heating step.

4550h/0334h