NL8004775A - CRYSTALLINE CHROME OXIDE SILICATE, METHODS FOR PREPARING IT, AND METHOD FOR CONVERSION OF HYDROCARBONS. - Google Patents

Description

• »K.O. 29,366

Crystalline chromium oxide silicate, processes for its preparation, and a process for the conversion of hydrocarbons .____

The present invention relates to new types of crystalline silicates containing chromium oxide and processes for their preparation. These preparations are suitable as catalysts for hydrocarbon processes, in particular dewaxing operations and olefin preparation.

Molecular sieve type crystalline zeolites are aluminosilicates, which contain a rigid three-dimensional structure of SiO4 and AlO4 tetrahedrons united by common oxygen atoms. The inclusion of aluminum atoms in the structure is too short of an electrical charge, which must be locally neutralized by the presence of additional positive ions in the structure. In natural zeolites and many of the synthetic zeolites, these ions are usually alkali metal or alkaline earth metal cations, which are quite mobile and are easily exchanged in different sizes according to conventional techniques for other cations. The cations occupy channels and interconnected spaces provided by the geometry of the structure.

U.S. Patent 5,702,886 discloses a new group of crystalline zeolites referred to as ZSM-5. The ZSM-5 type zeolites have a composition expressed in oxide molar ratios as follows: 0.9 * 0.2M2 / nO: W2 O: 5-100YO2: zH2 O wherein M is at least one cation , n is the valence, ¥ is aluminum or gallium, Y is silicon or germanium, and z has a value between 0 and 40. Members of the ZSM-5 family are reported to possess a random powder X-ray diffraction pattern with the following significant lines: 2

Table A

Interplanar space d (&): Relative intensity 11.1 ± 0.2 s.

10.0 i 0.2 s.

5 7.4 ± 0.15 z.

7.1 i 0.15 z.

6.5 i 0.1 z.

6.04) +01 z 5.97) z * 5.56 ± 0.1 z.

10 5.01 ± 0.1 z.

4.60 ± 0.08 z.

4.25 ί 0.08 z.

5.85 - 0.07 z.s.

5.71 i 0.05 s.

15 3.04 ί 0.05 z.

2.99 t 0.02 z.

2.94 ± 0.02 z.

The aforementioned values were determined according to conventional techniques, as described in the patent.

The patent teaches that ZSM-5 type zeolites are prepared by hydrothermal crystallization of a reaction mixture of tetrapropylammonium hydroxide, sodium oxide and an oxide of aluminum or gallium and an oxide of silicon or germanium.

U.S. Patent 5,941,871 discloses a crystalline metal organosilicate having the following composition in its anhydrous state: 0.9 ~ 0.2 [xR20 ± (1-x) M2 / no]]: <.005A1205:> SiO02 50 wherein M is a metal other than a metal group IIIA of the periodic system, n is the valence thereof, R is an alkyl ammonium group and x has a value between 0 and 1.

The disclosed compositions are prepared by hydrothermal crystallization of a reaction mixture of alkyl ammonium oxides, sodium oxides, water and oxides of a metal other than group UIA of the periodic table. Aluminum oxide appears in the product in small amounts due to contaminants from the reagents and / or equipment used in the synthesis. The random X-ray 8004775 3 ray powder diffraction analysis shows the following significant lines: fable 3

Interplanar space d (&): Relative intensity 5 11.1 - 0.2 s 10.0 - 0.2 s 7.4 ± 0.15 z 7.1 ± 0.15 z 6.3 £ 0.1 z

10 i 0.1 Z

5.56 £ 0.1 z 5.01 £ 0.1 z 4/7 - £ / 08 z 4.25 £ 0.08 z 15 3.85 £ 0.07 z.s.

3.71 i 0.05 s 3.04 £ 0.03 z 2.99 £ 0.02 z 2.94 £ 0.02 z 20 U.S. Patent 4,061,724 discloses a

crystalline silicon oxide, referred to as "silicalite". Silicalite is prepared by hydrothermal crystallization of a reaction mixture containing water, silicon oxide and an alkylonium compound, such as tetraethyl ammonium hydroxide, tetrapropyl ammonium hydroxide or the corresponding salts thereof, such as tetrapropyl ammonium bromide. Silicalite, after calcination in air at 600 ° C for one hour, shows the following X-ray diffraction pattern: Table C

30 _d - & _ Relative intensity 11.1 £ 0.2 z.s.

10.0 £ 0.2 z.s.

3.85 £ 0.07 z.s.

3.82 ± 0.0? s 35 3.76 - 0.05 s 5.72 ± 0.05 s

Table D presents the results of an X-ray diffraction analysis of a silicalite preparation after calcination containing 51.9 moles SiO 2 per mole tetrapropylammonium oxide 40: 4

Table D

d- & Relative d- & Relative _ intensity _ intensity 11.1 100 4.35 5 5 10.02 64 4.25 7 9.75 16 4.08 3 8.99 1 4.00 3 8.04 0, 5 3.85 59 7.42 1 3.82 32 10 7.06 0.5 3.74 24 6.68 5 3.71 27 6.35 9 3.64 12 5.98 14 3.59 0.5 5.70 7 3.48 3 15 5.57 8 3.44 5 5.36 2 3.34 11 5.11 2 3.30 7 5.01 4 3.25 3 4.98 5 3.17 0.5 20 4.86 0.5 3.13 0.5 4.60 3 3.05 5 4.44 0.5 2.98 10

All of the foregoing preparations have a pore diameter of about 6 angstroms and are individually suitable in certain hydrocarbon processing applications. However, ZSM-5 type aluminosilicates are too active in hydrocracking, for example, in cracking normal alkanes from a feed for dewaxing purposes. This strong activity results in high gas production and low liquid yields. On the other hand, silicalite as such is much less active and is primarily used as an absorbent for oil from oil-water mixtures.

It is, therefore, an object of the present invention to provide a novel composition which is suitable for dewaxing high liquid yield feeds for the production of olefins and for other hydrocarbon conversion processes.

8004775 5

3TIGUUB

The figure illustrates the ESCA spectra for chromium in the CZM chromium oxide silicates of the present invention and in silicalite impregnated with chromium obtained in Example V.

The present invention relates to a new crystalline chromium oxide silicate which is hydrothermally crystallized from a reaction mixture containing chromium. The chromium oxide silicates of the present invention have a chromium oxide: silica ratio, expressed in mole ratios of oxides greater than about 20: 1, and an X-ray diffraction pattern, which is characterized by the diffraction lines of Table E.

Table E

15 d-ü Relative intensity 11.1 - 0.2 z.s.

10.0 ± 0.2 z.s.

3.85 - 0.07 z.s.

3.82 ± 0.07 s 20 3.76 i 0.05 s 3.72 ± 0.05 s

The chromium oxide silicates, hereinafter referred to as CZM, have a composition, expressed in the anhydrous state in the number of moles of oxides, which consists of: R2O: aM20: bC2O ^ CS1O2 wherein R2O is a quaternary alkyl ammonium oxide, preferably tetrapropyl ammonium oxide , M is an alkali metal selected from the group of alkali metals consisting of lithium, sodium, potassium or mixtures thereof, preferably sodium, 30 a has a value between 0 and 1.5, c is greater than or equal to 12 and c / b is greater is then 20. The ratio c / b will usually vary between 20 and 3000, and is preferably in the range of 50 to 1000. This chromium oxide silicate exhibits the random powder X-ray diffraction lines shown in Table F.

8004775 6

Table F

Interplanar 2Θ Normalized space (doubled Bragg intensities d (Angstrom) angle) ____— - 5 11.2 ± 0.2 7.90 100 10.05 ± 0.12 8.80 70 9.75 ± 0.11 9.07 17 8.99 1 0.09 9.84 1 7.44 ± 0.06 11.90 1 10 6.71 - 0.05 13.20 7 6.36 ± 0.05 13.92 5.99 - 0.04 14.78 14 5.71 - 0.04 15.53 7 5.57 ± 0.04 15.91 10 15 5.36 ± 0.05 16.54 3 5.14 ± 0.05 17.25 1 5.02 ± 0.05 17. 65 5 4.98 - 0.05 17.81 5 4.61 ± 0.02 19.25 4 20 4.56 ± 0.02 20.57 5 4.25 ± 0.02 20.88 8 4.08 ± 0 .02 21.78 2 4.01 ± 0.02 22.18 3 5.86 ± 0.02 25.07 52 25 5.82 ± 0.02 25.29 32 5.75 1 0.02 25.73 17 5.72 ± 0.02 25.73 26 5.65 ± 0.02 24.40 12 5.60 ± 0.01 24.76 2 30 5.48 ± 0.01 25.58 2 5.44 ± 0.01 25.88 4 5.40 ± 0.01 26.24 1 3.35 1 0.01 26.60 3 3.31 ± 0.01 26.95 0 35 3.25 ± 0.01 27.45 2 5.05 ± 0.01 29.28 4 2.99 ± 0.01 29.90 9 2.96 ± 0.01 50.22 4

The X-ray diffraction patterns were obtained by normalized diffractometer methods using an X-ray tube with copper target, an 8004775 • graf 7 graphite crystal monochromator set to select the Κ-α doublet radiation of copper and a proportional counting tube, which is used to selectively measure the reflected Ε-α-doublet radiation. The patterns were recorded with a strip chart recorder and the diffraction peak intensities normalized to a scale of 0 to 100. The interplanar spaces, d (measured in angstroms), corresponding to the recorded diffraction peaks, were calculated.

The crystalline chromium oxide silicate is prepared by hydrothermal crystallization of an aqueous reaction mixture containing quaternary alkyl ammonium oxide, chromium oxide, silicon oxide and an oxide of an alkali metal from the group of the alkali metals consisting of lithium, sodium, potassium or mixtures thereof, preferably sodium.

The reaction mixture preferably has a composition, expressed in the number of moles of oxides, of _____ .... EgO * al ^ OïbC ^ O ^ icSiOgidHgO

Wherein a is greater than 0 but less than 5, c is in the range of 1 to 100, the ratio c / b is greater than 12 but less than 800, and d is in the range of 70 to 500. Preferably, a is in the range 0.05 to 1, c is in the range 2 to 20, the ratio c / b is in the range 50 to 600, and d is in the range 100 to 300. Hydrothermal crystallization is carried out at preferably performed at a temperature in the range of 100 to 200 ° C, more preferably at 125 to 175 ° 0, and even more preferably at 150 ° 0. The crystallization is conveniently carried out at the autogenous pressure of the reaction mixture.

CZM is suitable as a catalyst in hydrocarbon processing and is particularly useful in dewaxing treatments and olefin preparation.

In such processes, a hydrocarbon fill, such as a reformate, is contacted with the CZM catalyst under conversion conditions.

Normal alkanes in the reformate are cracked to yield significant amounts of olefins even in the presence of hydrogen.

Preferably, the reformate is contacted 8 with the CZM catalyst in the presence of hydrogen at a hydrogen partial pressure in the range of about 1000 to 27ΟΟ kPa and at a temperature in the range of 450 to 510 ° C. These conversion conditions allow the catalyst to be placed to receive the entire effluent from the reformer either in a separate reservoir after the reformer unit or as a layered catalyst bed in the final reformer reactor. A space-time velocity in the range of 0.5 to 5 should preferably be maintained.

The CZM catalyst of the present invention can be used with or without a matrix or binder. When a matrix is used, the CZM can conveniently be bound therewith in a catalyst to matrix weight ratio of about 95: 5 to 1: 100. In such cases, the matrix should contain substantially non-acidic products such as aluminum oxide or silicon oxide. A preferred binder is alumina, which can be powdered, milled together with the catalyst and mixed and extruded.

The chromium oxide silicates of the present invention contain crystalline structures identified by random powder X-ray diffraction patterns similar to the patterns exhibited by ZSM-5 aluminosilicates and silicalite. In the present invention, the chromium oxide should be present in the reaction mixture during hydrothermal crystallization. The molar ratio of silica to chromium oxide in the product composition is greater than 20 and preferably in the range of from 50 to 1000.

CZM can be hydrothermally crystallized from a reaction mixture containing suitable sources of chromium, silicon and sodium oxides, water and quaternary alkyl ammonium cations of the formula (R 1 R) *, wherein R represents an alkyl group of 35 to 4 carbon atoms.

Preferably R is ethyl, propyl or normal butyl, especially propyl. Examples of compounds which provide the desired cation in solution include tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetra-40-butylammonium hydroxide and the salts corresponding to these hydroxides 8004775 9 such as the chloride, bromide and iodide salts.

Suitable sources of silicon dioxide for the reaction mixture include alkali metal silicates such as a sodium silicate solution, as well as reactive forms of the silicon oxide sols, silica gels and smoked silicon dioxide. Silicon oxide sols, such as the commercially available brand Ludox, containing 30 wt% SiO 2, are particularly preferred. Since alumina will readily be incorporated into the crystal lattice, care should be taken to minimize the sources of alumina impurities. Commercially available silica sols usually contain 500 to 700 ppm Al2 O4 and at least a portion of the alumina will appear in the final product.

Generally, sodium, potassium or lithium can be added to the reaction mixture in the form of hydroxides or the corresponding salts thereof. Alkali metal silicates can also provide all or part of the required metals in addition to serving as a source of silicon oxide. Preferred reaction sources include sodium hydroxide, sodium nitrate, sodium silicate solution or water glass.

Chromium sources include soluble chromium salts such as chromium chloride, chromium sulfates and chromium nitrates, the nitrates being particularly preferred. The chromosilicates in the present invention are preferably crystallized from a basic reaction mixture with a pH in the range of 10 to 13. To obtain a mixture in this pH range it may be necessary depending on the source of the reagents, raise the pH by adding additional base to the mixture (e.g., ammonium hydroxide or alkali metal hydroxides) or lowering the pH to the desired range using an acid (e.g., inorganic acids). Na-35, lithium, or potassium hydroxides are particularly suitable for controlling the pH in an upward direction, since the alkali metals are also required as reagents in the crystallization process.

Preferably, the reaction mixture, expressed in terms of the molar ratio of oxides, should be 0.05 to 5 moles of sodium, potassium and 7 7 r 10 lium or lithium oxide, 1 to 100 moles of SiOg, 70 to 500 moles of water and a mole ratio of silica to the number of moles of chromium oxide equal to or greater than 12 per mole. Preferred reaction mixtures contain 0.05 to 5 moles of sodium, potassium or lithium oxide, preferably sodium oxide, 2 to 20 moles of silica, 100 to 500 moles of water, and a mole ratio of silica to chromium oxide in the range of 30 to 600.

After the reaction mixture has been prepared, the mixture is heated to a temperature in the range of from 100 to 200 ° C, preferably from 125 to 175 ° C, and more preferably at a temperature of 150 ° C and at this temperature and at autogenous pressure held until the hydrated forms of CZM are formed. Crystalline hydrated CZM will usually form and precipitate from the reaction mixture within 6 hours to 6 days and usually within 48 hours. The product crystals are separated from the mother liquor, such as by cooling to ambient temperature, filtration and washing. Dehydrated or low sodium forms of the product can be prepared by conventional techniques from the prepared crystals.

Example I

A reaction solution was prepared by dissolving 47 * 9 g of tetrapropyl ammonium bromide in 35 ml of water and adding to the solution 7.2 g of sodium hydroxide dissolved in 30 ml of water. 8 g Cr (NO 2 dissolved in 20 ml water and 116 g silica sol, Ludox brand (30 wt% S1O2) were added to the EPA Bfi-NaOH mixture with rapid stirring.

The total reaction mixture was treated in an open Teflon flask at a temperature of 150 ° C and at autogenous pressure for 48 hours. At the end of the hydrothermal crystallization period, the product crystals were filtered from the solution and washed with water. The crystals were dried at 121 ° C overnight and then calcined at 450 ° C for 8 hours. They had the X-ray diff fraction pattern, as given in Table Έ, and had a composition expressed in number moles of oxides of 0.6Na2 O: C 2 O 2 28 OS 10 O 2 after washing with water containing N 1 N 2 O 2.

4 0 8004775 11

Example II

2.3 g of sodium nitrate dissolved in 10 ml of water and 5.5 Gr of Gr (NO2), .9H2O dissolved in 10 ml of water were added successively to 100 g of a 25% solution of 5 tetrapropylammonium hydroxide with rapid stirring. 80 g of silicon oxide sol, brand ludox (30 wt% SiQ2), were added to the previous solution and the total mixture was autoclaved at 144 ° C for 2 days at the vapor pressure of the solution. The product crystals were filtered from the solution and recovered, exchanged with ammonium nitrate, washed with water, dried at 121 ° C overnight and calcined at 450 ° C for 8 hours. X-ray analysis gave the diffraction pattern as in Table 3P.

The crystals had a composition expressed in 15 mol oxides of 0.5Na2 O: Cr2O: 66S1O2.

Example III

When testing the CZM catalyst, a sample of the chromium-silica-silica prepared according to Example 20 II was mixed with a binder (peptized Ziegler aluminum oxide-Catapal) in a weight ratio of 1: 1 , extruded, exchanged with ammonium acetate, dried and calcined at 450 ° C for 8 hours. The exchange and calcination were repeated twice. The non-alumina portion 25 of the catalyst had a composition, expressed in the number of moles of oxides, of 0.01Ha2O: Cr2O5: 2253iO2

A feed of bottoms from an iso-separator of 385 ° C +, with a pour point of + 33 ° C, was passed over the catalyst 30 with hydrogen at a pressure of 6800 kPa, a temperature of 350 ° C and a space-time velocity of 2. The hydrogen feed to the reactors was kept at 17.8 liters per liter of feed. Under these conditions, an efficiency of 83.8% by weight of the product 370 ° C + was obtained with a pour point of -30 ° C. For comparative purposes, a similar test was performed using the same weight ratio of silicalite prepared according to U.S. Pat. No. 4,061 * 724 to Catapal binder. However, in order to obtain a comparable C + 40 product, an operating temperature of 406 ° C was required, which meant that at 775 ° C.

very clearly demonstrates the greater activity of the chromium oxide silicate relative to the prior art. Example IV

A series of tests were conducted to investigate the activity of CZM, silicalite and silicalite impregnated with chromium after the synthesis using Cr (NO 4, 9, 0 and standard techniques).

The CZM catalyst was prepared as follows: The screen product of Example II was exchanged five times with a 10 25% ammonium acetate solution at 80 ° C, washed with water, dried at 121 ° 0 overnight and calcined at 450 ° C for 8 hours. The exchange, drying and calcination were repeated.

Silicalite was prepared using the technique of U.S. Patent 4,061,724. The catalyst was prepared by exchanging silicalite with a 20 percent ammonium nitrate solution at 80 ° C four times, washing with water, drying at 121 ° C overnight, and calcining at 450 ° C for 8 hours.

The chromium-impregnated silicalite was prepared by impregnating the previous catalyst with a solution of CrCNO4] -9 ^ 0 by the pore filling method.

The catalyst was dried at 121 ° C overnight and calcined at 450 ° C for 8 hours.

Investigations of the three catalysts are provided in Table G.

Table G

Al (dnm) Na (dom) CrCwt.%) CZM 380 <50 0.56 30 silicalite 400 <50 0 silicalite impregnated with chromium 400 100 0.5

The catalysts were bonded with Catapal alumina, extruded, dried and calcined at 450 ° C for 8 hours. Samples of each were placed in porcelain crucibles in a calcination pot and treated in a 100% steam atmosphere at 760 ° C.

Steamed and non-steamed catalyst samples were then tested according to a "pulse decane cracking test" 40 to determine their cracking activity. Test Method 8004775 was as follows: 0.1-0.5 catalyst were mixed with 1 g of acid washed and neutralized alundum and filled into a 4.75 mm stainless steel reactor tube with the remaining space filled with alundum. The reactor contents 5 were calcined at 450 ° C for one hour. The reactor was then placed in a gripper oven and the reactor outlet connected to the inlet of a gas chromatograph. The inlet was connected to the carrier gas line of the gas chromatograph. Helium was passed through the system at 30 cm / min. 10 microliter pulses of n-decane were injected through a septum over the reactor and reaction products were determined by standard gas chromatographic analysis. Blank tests with alundum showed no conversion under the experimental conditions, nor did a 100% Catapal 15 alumina catalyst.

A pseudo first order cracking rate constant, k, was calculated using the formula K = -L in -ΙΑ 1-x where A is the weight of zeolite in grams and x is the fractional conversion to products boiling below decane. , is.

Table H shows the resulting values of the ln of k as a function of the steam time at 760 ° C.

Table H

After steaming at 760 ° C

25 0_h 6_h 24 h

At> 0 -1.85 -2.70 silicalite -1.40 -3.00 -4.35 silicalite impregnated with chromium> 0 -2.65 -4.20 30 Without steaming, both chromium-containing catalysts were very active. After 6 hours of steaming, C2M was about three times as active as silicalite, while the chrome-impregnated silicalite was only about 1.4 times as active. After 24 hours of steaming, CZM was five times more active than silica-35 calite, while the silicalite impregnated with chromium had only little improved activity. These data demonstrate the significantly different catalytic activity obtained with the CZM chromium oxide silicates from low alumina silicates, which may or may not have been impregnated with chromium.

Example V

ESCA analysis of chromium silicalites

A series of tests were performed to demonstrate the differences between the chromium in CZM chromium oxide silicates and in silicalite impregnated with chromium.

Samples of CZM and chromium impregnated silicalite prepared as in Example IV (but not steamed) were tested in a Hewlett-Packard 5950A SSOA (Electron 10 Spectroscopy for Chemical Analysis) Spectrometer. The samples were not bound in an assembly. Both samples were powders and were placed in the spectrometer by spraying on double-sided adhesive tape. Al Kcc radiation passed through a monochromator was used as an excitation source. Electrons of 2 eV from an electron gun with an emission setting of 0.3 milliamps were used to compensate for sample charge effects.

The pressure in the spectrometer during the analysis was approximately 0.27 x 10 kPa. For chromium a 50 eV window 20 was scanned with 256 points, while for silicon, carbon and oxygen 20 eV windows were scanned with 256 points. The different windows were scanned several times and then the signal was averaged to obtain good signal-to-sound ratios and separation. The analyzer was calibrated by determining the

Au (4f 7/2) binding energy (BE) at 84.0 ^ 0.1 eV. After taking into account the sample charge effects, the Cr (2p3 / 2) BE 2 eV was lower in CZM than in chromium impregnated silicalite, while the Si (2p) and 0 (ls) BEs of the two samples were the same within the experimental accuracy (-0.1 eV). The figure shows the difference in the Cr (2p) lines for CZM and chrome-impregnated silicalite. Herb big difference. in Cr BE's, it is surprising that the chromium is in different oxidation states in the two samples.

Visual examination of the CZM and the chromium impregnated silicalite provides further evidence of differences between the samples. After the calcination step of the preparation (8 hours at 450 ° C), the CZM sample was light green in 40 color, while the chrome-impregnated silicalite was yellow 8004775. This shows the increased stability of the chromium in the CZM chromium oxide silicate compared to the chromium impregnated silicalite.

The synthetic chromium oxide silicates can be used as prepared or can be heat treated (calcined). It is usually desirable to remove alkali metal cation by ion exchange and replace it with hydrogen, ammonium or any desired metal ion. The chromium oxide silicate can be used in intimate combination with hydrogenation components, such as tungsten, vanadium, molybdenum, rhenium, nickel, cobalt, chromium, manganese or a precious metal such as palladium or platinum, for those applications in which a hydrogenation dehydrogenation function is desired is. Conventional metal cations can include rare earths, Group IIA and Group VIII metals of the periodic table, as well as their mixtures, cations of metals such as rare earths, Mn, Ca, Mg, Zn, Cd, Pt,

Pd, Ni, Co ', Ti, Al, Sn, Pe and Co are particularly preferred.

The hydrogen, ammonium and metal components can be exchanged in the chromium oxide silicate. The chromium oxide silicate can also be impregnated with the metals, or the metals can be physically thoroughly mixed with the chromium oxide silicate using known techniques. Conventional ion exchange techniques include contacting the synthetic chromium oxide silicate with a solution that replaces salt of the desired

Although the cation or cations contains a wide variety of salts can be used, chlorides and other halides, nitrates and sulfates are particularly preferred. Representative ion exchange techniques have been described in many patents, such as, for example, U.S. Pat. Nos. 3-14-0.249, 3-14-0.251 and 3-14-0.253, ion exchange may take place before or after the zeo-35 has been calcined.

After contact with the saline of the desired replacement cation, the chromium oxide silicate is usually washed with water and dried at a temperature from 65 ° C to about 315 ° C. After washing, it can be calcined in air or in a 40 inert gas at temperatures of about ft π o 4 7 7 5 200 ° C to 820 ° C for periods of 1 to 48 hours or more, to prepare a catalytically active product , particularly suitable in hydrocarbon conversion processes.

Regardless of the cations present in the synthesized form of the chromium oxide silicate, the spatial arrangement of the atoms constituting the base crystal lattice remains essentially unchanged. The exchange of cations has little or no effect on the lattice structures.

The chromium oxide silicates can be produced in a wide variety of physical forms. Generally speaking, they may be in the form of a powder, a granule, or a molded product, such as an extrusion product having a particle size sufficient to pass and be retained by a 2-mesh (Tyler) mesh screen. on a 400 mesh screen (Tyler). In cases where the catalyst is formed, such as by extrusion with an organic binder, the chromium silicate can be extruded before drying or dried or partially dried and then extruded

The chromium oxide silicate can be formulated with other materials that can withstand the temperatures and other conditions used in organic conversion processes. Such matrix materials include active and inactive materials and synthetic or naturally occurring zeolites, as well as inorganic materials such as clays, silica and metal oxides. The latter may in the form of gelatinous precipitates, sols or gels, including mixtures of silica and metal oxides, in the natural form. Use of a material in conjunction with the synthetic chromium oxide silicate, that is, combined with that which is active, tends to improve the conversion and selectivity of the catalyst in certain organic conversion processes. Inactive materials suitably serve as diluents to control the degree of conversion in a given process so that products can be obtained economically without the use of other reaction rate controls. 40 The chromium oxide silicates can be included in clays naturally occurring in 8004775 17, such as bentonite and kaolin. These materials, i.e. clays, oxides, etc., partially function as binders for the catalyst. It is desirable to provide a catalyst with good breaking strength, because in petroleum refining the catalyst is often subject to rough treatment. This tends to break the catalyst into powdery materials, which cause processing problems.

Naturally occurring clays that can be formulated with the chromium oxide silicates of the present invention include the groups of montmorillonite and kaolin, to which the sub-bentonites belong and the kaolin groups known as Dixie, McHamee, 15 Georgia and Florida clays or others, in which the major mineral constituent is halloysite, kaolinite, dickite, nacrite, or anauxite. Fibrous clays such as sepiolite and attapulgite can also be used as carriers. Such clays can be used in the raw state, such as originally recovered or first subjected to calcination, acid treatment or chemical modification.

In addition to the aforementioned materials, the chromium oxide silicate can be formulated with porous matrix materials and mixtures of matrix materials such as silica, alumina, titanium oxide, magnesia, silica-alumina, silica-magnesia, silica-zirconia, silica-thorium oxide, silica beryllium oxide, silica-titanium oxide, titanium oxide-zirconium oxide, as well as ternary compositions such as silicon oxide-alumina-thorium oxide, silica-alumina-zirconium oxide, silica-alumina-magnesium oxide, and silica-magnesium oxide-zirconium oxide.

The matrix may be in the form of a ball.

The chromium oxide silicates can also be formulated with other zeolites, such as synthetic and natural faujasites, erionites and mordenites (eg X and Y). They can also be formulated with synthetic zeolites.

40 The relative proportions of the crystalline chromium

o Λ fl A 7 7 K

oxide silicates of the present invention and the inorganic oxide gel matrix can be varied widely. The chromium oxide silicate content can range from about 1 to about 90 wt%, but usually ranges from about 2 to about 50 wt% of the composition.

Chromium oxide silicates are useful in hydrocarbon conversion reactions. Hydrocarbon conversion reactions are chemical and catalytic processes in which carbon-containing compounds are changed to other carbon-containing compounds. Examples of hydrocarbon conversion reactions include catalytic cracking, hydrocracking and olefin and aromatics formation reactions. The catalysts are useful in other petroleum refining and hydrocarbon conversion reactions, such as isomerizing n-alkanes and naphthenes, polymerizing and oligomerizing ethylenically or ethynically unsaturated compounds such as isobutylene and butene-1, reforming, alkylating, isomerizing polyalkyl substituted aromatics (eg ortho-xylene) and disproportionating aromatics (eg toluene) to provide a mixture of benzene, xylenes and higher methylbenzenes.

The chromium oxide silicates can be used in the processing of hydrocarbonaceous feeds. Hydrocarbonaceous feeds contain carbon compounds and can come from many different sources, for example, untreated petroleum fractions, recycled petroleum fractions, slate oil, liquefied carbon, tar sands oil and generally any carbon containing fluid sensitive to zeolite-like catalytic reactions. Depending on the type of processing that the hydrocarbonaceous feed is to undergo, the feed may contain metal or be metal free, and may also contain much or little nitrogen or sulfur impurities. However, it can be assumed that in general the processing will be more efficient (and the catalyst more active) the lower the nitrogen content of the feed.

The conversion of hydrocarbonaceous feeds can be by any conventional method, for example in fluidized bed, moving bed reactors 8004775 or fixed bed depending on the type of process desired. The formation of the catalyst particles will vary depending on the conversion process and the processing method.

Using chromium oxide silionates containing 5 hydrogenation components, heavy petroleum stocks, recycle stocks and other hydrocrackable stocks can be hydrocracked at temperatures from 300 ° C to 525 ° C using hydrogen to hydrocarbon fill molar ratios of 1 to 100. The pressure can range from about 70 to 55,000 kPa and the space-time rate from 0.1 to 30. For these purposes, the chromium silylates can be formulated with mixtures of inorganic oxide supports, as well as with faujasites, such as X and Y.

The chromium oxide siliates can be used for catalytic cracking using temperatures from 260 ° G to 625 ° 0, pressures from below atmospheric to several hundred atmospheres, and other standard conditions.

Chromium oxide siliates can be used to dewax the hydrocarbonaceous feeds by selectively removing straight chain and slightly branched chain alkanes. The process conditions can be those of hydrocaraffinizing - weak hydrocracking, or they can be run at lower pressures in the absence of hydrogen. Dewaxing produces significant amounts of olefins from the cracked paraffins.

Chromium oxide siliates can also be used in reforming reactions using temperatures from 360 ° C to 600 ° C, pressures from 100 kPa to 3500 kPa, and over 30 rates from 0.1 to 20. The hydrogen to hydrocarbon molar ratio can generally be 1 to 20.

The catalyst can also be used to hydroisomerize normal alkanes when provided with a hydrogenation component, for example, platinum. Hydro-35 isomerization is generally conducted at temperatures from 200 ° C to 375 ° C and space time rates from 0.01 to 5 · The hydrogen to hydrocarbon molar ratio is from 1 to 1 * 5 * 1. Also, the catalyst can be used for isomerizing olefins using temperatures from 140 ° C to 320 ° C.

8004775

Other reactions which can be accomplished using the catalyst of the present invention, which contain a metal, for example, platinum, are hydrogenation dehydrogenation reactions, denitrogenation reactions and desulfurization reactions.

Chromium oxide silicates can be used in hydrocarbons, cool conversion reactions with active or inactive carriers, with organic or inorganic binders, and with or without added metals. These reactions are known in the art, as are the reaction conditions.

8004775

Claims (24)

1. Crystalline chromium oxide silicate having a mole ratio of oxides of SiCl 3: 0 ^ 0 greater than about 20: 1 and having the random powder X-ray diffraction lines 5 of Table E. 2. Crystalline chromium-silicate preparation, which in the anhydrous state, expressed in moles of oxides E ^ O: aM ^ O: "kC ^ O ^: CS1O2, wherein Eg0 is a quaternary alkyl ammonium oxide, 10. is an alkali metal such as lithium, sodium, potassium or mixtures thereof, a is greater than 0 but less than 1.5, c is greater than or equal to 12, and c / b is greater than 20. and which chromium oxide silicate is the random powder X-ray diffraction pattern of Table E has. Crystalline chromium oxide silicate according to claim 2, characterized in that EgO is tetrapropylammonium oxide and M is sodium. 4. Process for the conversion of hydrocarbons, characterized in that a hydrocarbon charge is contacted under conversion conditions with the catalyst of claim 1. 5. Process for improving the quality of a reformate containing normal alkanes, characterized in that the reformate is contacted with the catalyst of claim 1 under conversion conditions, wherein a substantial part of the normal alkanes are cracked into lighter gaseous products . 6. Process according to claim 5, characterized in that the gaseous products contain olefins. Process according to claim 5 or 6, characterized in that the conversion conditions involve the presence of hydrogen. 8. Process according to claims 5 to 7, characterized in that the conversion conditions include a partial hydrogen pressure in the range from 100 to 3000 kPa and a temperature in the range from 400 to 550 ° C. Method according to claim 8, characterized in that the conversion conditions include a space velocity in the range of 0.1 to 10 h. and nk 775 10. Process for preparing crystalline chromium oxide silicate, characterized in that a reaction mixture containing a quaternary alkyl ammonium oxide, an oxide of an alkali metal such as lithium, sodium, potassium or mixtures thereof, chromium oxide and silicon oxide "is hydrothermal crystallizes, the reaction mixture having a composition expressed in moles of oxides of RgO:: c ^^^ 2: wherein RgO is a quaternary alkyl ammonium oxide, M is an al-potassium metal such as lithium, sodium, potassium or mixtures thereof, a greater than 0 but is less than 5, c is in the range of 1-100, c / b is greater than 12, and d is in the range of 70-500. 11. Process according to claim 10, characterized in that 1 ^ 0 is tetrapropylammonium oxide and M is sodium. A method according to claim 11, characterized in that a is in the range 0.05-1, c is in the range 2-20, c / b is in the range 50-600 and d is in the range range of 100-500. Process according to claims 10 to 12, characterized in that the hydrothermal crystallization is carried out at a temperature in the range from 100 to 200 ° C. 14. Process according to claims 10 to 13, characterized in that the hydrothermal crystallization is carried out at autogenous pressure. Crystalline chromium oxide silicate obtained by one or more of the methods of claims 10 to 14. Process for the conversion of hydrocarbons, characterized in that a hydrocarbonaceous feed is contacted with the crystalline chromium oxide silicate according to claim 1 under hydrocarbon conversion conditions. A method according to claim 16, characterized in that the method is hydrocracking. A method according to claim 16, characterized in that the method is an extraction. 19. A method according to claim 16, characterized in that the method is a reformation. 8004775 A method according to claim 16, characterized in that the method is a polymerization or oligomerization of olefins. 21. A method according to claim 16, characterized in that the method is an isomerization. Method according to claim 16, characterized in that the method is a disproportionation. Process according to claim 16, characterized in that the process is an alkylation. A method according to claim 16, characterized in that the method is a catalytic cracking. * * * * * * * 8004775