| PATENT ASSIGNEE'S COUNTRY | France |
| UPDATE | 12.99 |
| PATENT NUMBER | This data is not available for free |
| PATENT GRANT DATE | 07.12.99 |
| PATENT TITLE |
Catalyst comprising a dioctahedral 2:1 phyllosilicate prepared in a fluoride medium and a process for the hydroconversion of petroleum feeds |
| PATENT ABSTRACT |
The invention concerns a catalyst comprising at least one catalytic element, and a support comprising 20-99% by weight of at least one matrix, 1-80% by weight of at least one 2:1 dioctahedral phyllosilicate containing fluorine and 0-30% by weight of at least one Y zeolite. The catalytic element is from groups VI and/or VIII. Phosphorous can be present. The invention also concerns a process for the hydroconversion of said catalyst. |
| PATENT INVENTORS | This data is not available for free |
| PATENT ASSIGNEE | This data is not available for free |
| PATENT FILE DATE | 26.02.97 |
| PATENT REFERENCES CITED | Abstract, WPI/Derwent, No. 92-053997[07] Japan Jan. 6, 1992. |
| PATENT CLAIMS |
We claim: 1. A catalyst comprising a support comprising 20-99% by weight of at least one matrix, 1-80% by weight of at least one dioctahedral 2:1 phyllosilicate containing fluorine, and 0.1-30% by weight of at least one Y zeolite; and at least one catalytic element. 2. A catalyst according to claim 1, wherein the catalytic element is a group VI element or a group VIII element, and wherein the catalyst contains 1-40% by weight of said element(s). 3. A catalyst according to claim 2, also containing phosphorous. 4. A catalyst according to claim 3, containing less than 15% phosphorou. 5. A catalyst according to claim 2, wherein the dioctahedral 2:1 phyllosilicate is synthesized in a fluoride medium. 6. A catalyst according to claim 1, also containing phosphorous. 7. A catalyst according to claim 6, containing less than 15% of phosphorous. 8. A catalyst according to claim 6, wherein the dioctahedral 2:1 phyllosilicate is synthesized in a fluoride medium. 9. A catalyst according to claim 1, in which the dioctahedral 2:1 phyllosilicate is synthesised in a fluoride medium. 10. A catalyst according to claim 1, wherein the dioctahedral 2:1 phyllosilicate has: a) the following general chemical formula for a half cell; M.sup.m+.sub.x/m ((Si.sub.(4-x) T.sub.x)(T.sub.2 .quadrature..sub.1)O.sub.10 (OH.sub.(2-y) F.sub.y)).sup.x- where T represents an element selected from the group consisting of group IIIA elements and iron; where M is at least one compensating cation from the reaction medium or introduced by at least one ion exchange process, and M is selected from the group consisting of group IA, IIA, and VIII elements, a proton, organic cations containing nitrogen, ammonium cations, and rare earth cations; where m is the valency of cation M; where x is a number which is in the range 0 to 2; y is a number which is greater than 0 and less than or equal to 2; and .quadrature. represents an octahedral cavity; b) an X ray diffraction diagram characterized by the presence of the following lines: a line corresponding to a d.sub.hkl of 1.49.+-.0.01.times.10.sup.-10 m; two further lines at d.sub.hkl values of: 4.46.+-.0.02.times.10.sup.-10 m and 2.56.+-.0.015.times.10.sup.-10 m; at least one 001 reflection such that d.sub.001 is: 12.5.+-.3.times.10.sup.-10 m, under appropriate humidity conditions for hydration of the compensating cation; c) a fluorine content which is such that F/Si molar ration is in the range 0.1 to 4; d) at least one signal at -133 ppm.+-.5 ppm in .sup.19 F NMR, with magic angle spinning; said phyllosilicate having been synthesized in a fluorinated medium in the presence of HF acid and at a pH of less than 9. 11. A catalyst according to claim 10, in which the pH for synthesis is in the range 0.5 to 6.5. 12. A catalyst according to claim 1, in which the dioctahedral 2:1 phyllosilicate is bridged. 13. A catalyst according to claim 12, in which the dioctahedral 2:1 phyllosilicate is bridged using a process comprising at least one treatment comprising a first step in which a solution of polycations is brought into contact with the phyllosilicate to be bridged comprising exchangeable cations, to form the reaction mixture; then in a second step, exchange is carried out between the polycations and the exchangeable cations of the phyllosilicate: and finally, in a third step the product obtained is separated by filtering and washed; said treatment being characterized in that: the mass of the phyllosilicate to be bridged per total solution volume is in the range 1 to 200 g/l; the second, exchange, step is carried out at a temperature which is in the range 15.degree. C. to 100.degree. C.; said second step has a duration which is in the range 1 minute to 3 hours; the separation time in the third step is in the range 20 seconds to 60 minutes per litre of solution containing the product to be separated in suspension. 14. A catalyst according to claim 13, wherein the polycations are [Al.sub.13 O.sub.4 (OH).sub.24 (H.sub.2 O).sub.12 ].sup.7+, [Zr.sub.4 (OH).sub.8 (H.sub.2 O).sub.16 ].sup.8+, [ZrOCl.sub.2 Al.sub.8 (OH).sub.20 ].sup.4+, or polycations containing at least one element selected from the group consisting of zirconium, titanium, molybdenum and vanadium. 15. A catalyst according to claim 1, wherein the catalyst support comprises 20% to 99% by weight of matrix, 1% to 80% by weight of dioctahedral 2:1 phyllosilicate, and 0.1 to 30% by weight of at least one Y zeolite. 16. A catalyst according to claim 1, wherein the catalyst support comprises 30% to 96% by weight of matrix, 4% to 70% by weight of dioctahedral 2:1 phyllosilicate, and 0.1 to 20% by weight of at least one Y zeolite. 17. A catalyst according to claim 1, wherein the catalyst support comprises 50% to 85% by weight of matrix, 15% to 50% by weight of dioctahedral 2:1 phyllosilicate, and 0.1 to 10% by weight of at least one Y zeolite. 18. A catalyst according to claim 1, wherein the matrix is selected from the group consisting alumina, silica, magnesia, titanium oxide, zirconia, aluminum phosphate, titanium phosphate, zirconium phosphate and alumina-boron oxide combinations. 19. A catalyst according to claim 1, prepared by impregnation of the formed and calcined support, using at least one solution containing at least one element from group VI and, simultaneously or subsequently, using at least one solution containing at least one element from group VIII, followed by final calcining. 20. A process for hydrocracking of heavy cuts, comprising subjecting said cuts to effective hydrocracking conditions in the presence of a catalyst in accordance with claim 1. 21. A process for hydrocracking of heavy cuts, comprising subjecting said cuts to effective hydrocracking conditions in the presence of a catalyst in accordance with claim 2. 22. A process for hydrocracking of heavy cuts, comprising subjecting said cuts to effective hydrocracking conditions in the presence of a catalyst in accordance with claim 6. 23. A process for hydrocracking of heavy cuts, comprising subjecting said cuts to effective hydrocracking conditions in the presence of a catalyst in accordance with claim 7. 24. A process for hydrocracking of heavy cuts, comprising subjecting said cuts to effective hydrocracking conditions in the presence of a catalyst in accordance with claim 9. 25. A process for hydrocracking of heavy cuts, comprising subjecting said cuts to effective hydrocracking conditions in the presence of a catalyst in accordance with claim 10. -------------------------------------------------------------------------------- |
| PATENT DESCRIPTION |
The present invention concerns a catalyst comprising at least one catalytic element and a support comprising at least one 2:1 dioctahedral phyllosilicate containing fluorine, optionally and preferably bridged, at least one matrix and optionally, at least one Y zeolite with a faujasite structure. The invention also concerns a process for the hydroconversion of heavy petroleum feeds using this catalyst. Hydrocracking of heavy petroleum feeds is a very important refining process which can produce lighter fractions such as gasolines, jet fuels and light gas oils from surplus heavy feeds which are not very valuable, which fractions the refiner needs in order to adapt production to market demands. In comparison with catalytic cracking, catalytic hydrocracking is intended to provide very high quality middle distillates, jet fuels and gas oils. In contrast, the gasoline produced has a much lower octane number than that from catalytic cracking. Catalysts used for hydrocracking are all bifunctional, combining an acid function with a hydrogenating function. The acid function is provided by supports with large surface areas (150 to 800 m.sup.2 .g.sup.-1 in general) with superficial acidity, such as halogenated aluminas (in particular chlorinated or fluorinated), combinations of boron oxide and aluminium, amorphous silica-aluminas and zeolites. The hydrogenating function is provided either by one or a plurality of metals from group VIII of the periodic classification of the elements such as iron, cobalt, nickel, ruthenium, rhodium, palladium, osmium, iridium and platinum, or by a combination of at least one metal from group VI of the periodic classification of the elements such as chromium, molybdenum and tungsten and at least one group VIII metal. The balance between the two functions, acid and hydrogenating, is a fundamental parameter which governs the activity and selectivity of the catalyst. A weak acid function and a strong hydrogenating function result in catalysts which are of low activity, which operate generally at high temperatures (greater than or equal to 390.degree. C.) and at low space velocities (HSV expressed as the volume of feed to be treated per unit volume of catalyst per hour generally less than or equal to 2) but have very high selectivity towards middle distillates. In contrast, a strong acid function and a weak hydrogenating function produces very active catalysts but with poor selectivity towards middle distillates. The correct choice of each of these functions is the problem which must be solved in order to adjust the activity/selectivity couple of the catalyst. It is thus of major interest in hydrocracking to have wide flexibility available on a number of levels: flexibility as regards the catalysts used, which results in flexibility in the feeds to be treated and in the products obtained. The great majority of conventional hydrocracking catalysts are constituted by supports which are weakly acidic, such as amorphous silica-aluminas. Such systems are used to produce very high quality middle distillates and, when the acidity is very low, oil stock. Amorphous silica-aluminas are weak acid supports. Many of the hydrocracking catalysts on the market are constituted by silica-alumina associated with either a group VIII metal or, as is preferable when the amount of heteroatomic poisons in the feed exceeds 0.5% by weight, an association of sulphides of metals from groups VIB and VIII. Such systems have very good selectivity towards middle distillates and high quality products are formed. For the most weakly acidic among them, such catalysts can also produce lubricant stock. As already stated, the disadvantage of all of such catalytic systems based on an amorphous support is their low activity. Our research on a large number of zeolites and crystalline microporous solids has led to the surprising discovery that a catalyst containing at least one dioctahedral 2:1 phyllosilicate containing fluorine, preferably synthesised in a fluoride medium and preferably bridged, optionally and advantageously combined with a Y zeolite with a faujasite structure, can result in substantially improved selectivity towards middle distillates compared with known prior art catalysts. Dioctahedral 2:1 phyllosilicates are minerals which are formed by layering elementary sheets. Each sheet comprises two tetrahedral layers located one on each side of an octahedral layer. The tetrahedral layer is constituted by .DELTA.O.sub.4 tetrahedra, 3 out of 4 vertices being common to 2 tetrahedra and one vertex being free, giving the formula .DELTA.O(.sub.3/2+1), .DELTA. representing a tetrahedral cavity and O representing an oxygen atom. The octahedral layer is constituted by .DELTA.O.sub.6 octahedra, the 6 vertices being common to 3 octahedra, giving the formula O.sub.6/3. .DELTA. represents an octahedral cavity. By linings the context of a sheet to a half unit cell, 4.DELTA..sub.4 O.sub.6+4) tetrahedra are located two by two on each side of 3 .quadrature..sub.3 O.sub.6 octahedra and have 4 vertices in common: .DELTA.4.quadrature.3O.sub.(12). Two O atoms in the octahedral layer do not participate in this sharing and are saturated with H atoms: .DELTA..sub.4 .quadrature..sub.3 O.sub.10 (OH).sub.2. The tetrahedral cavities .DELTA. are usually occupied by silicon atoms and two out of three octahedral cavities .quadrature. are occupied by aluminum atoms: Si.sub.4 Al.sub.2 .quadrature.O.sub.10 (OH).sub.2. This structure is electrically neutral. The tetrahedral element silicon can be completely substituted by trivalent elements such as aluminium or gallium. Similarly, the octahedral element aluminium can be substituted by divalent elements (for example Mg or Fe) and/or monovalent elements (for example Li). These substitutions result in an overall negative charge in the structure. This necessitates the existence of exchangeable compensating cations located in the space between the sheets. The thickness of the space between the sheets depends on the nature of the compensating cations and their hydration. This space is also capable of accepting other chemical species such as water, amines, salts, alcohols, bases etc. The existence of --OH groups causes thermal instability due to a dehydroxylation reaction with equation: 2-OH.fwdarw.--O--+H.sub.2 O. In this respect, the introduction of the element fluorine during synthesis into the structure in place of the O--H groups produces phyllosilicates with greatly improved thermal stability. The general chemical formula (for a half-cell) of dioctahedral 2:1 phyllosilicate synthesised in a fluorine medium before bridging is as follows: M.sup.m+.sub.x/m ((Si.sub.(4-x) T.sub.x)(T.sub.2 .quadrature..sub.1)O.sub.10 (OH.sub.(2-y)F.sub.y)).sup.x- where T represents an element selected from group IIIA and iron; M is at least one compensating cation from the reaction medium or introduced by at least one ion exchange process, selected from the group formed by cations of elements from groups IA, IIA and VIII of the periodic classification of the elements, rare earth cations (cations of elements with atomic number 57 to 71 inclusive), organic cations containing nitrogen (including alkylammonium and arylammonium cations and the ammonium cation), and a proton; m is the valency of cation M; x is a number which is in the range 0 to 2; y is a number which is greater than 0 and less than or equal to 2; and represents an octahedral cavity. The X ray diffraction diagram is characterised by the presence of the following lines: a line corresponding to a d.sub.hkl of 1.49.+-.0.01.times.10.sup.-10 m; two lines at d.sub.hkl values of 4.46.+-.0.02.times.10.sup.-10 m and 2.56.+-.0.015.times.10.sup.-10 m; at least one 001 reflection such that d.sub.001 is 12.5.+-.3.times.10.sup.-10 m depending on the nature of the compensating cation and its hydration at the humidity under consideration. Preferably, the fluorine content is such that the F/Si molar ratio is in the range 0.1 to 4. The dioctahedral 2:1 phyllosilicate also has at least one signal at -133 ppm (.+-.5 ppm) in .sup.19 F NMR, with magic angle spinning. The phyllosilicates are synthesised in a fluorinated medium in the presence of HF acid and at a pH of less than 9, preferably in the range 0.5 to 6.5. The preparation of these types of solids in a fluoride medium and their characterisation are described in French patent FR-A-2 673 930 and in a publication of the 202.sup.nd meeting of the American Chemical Society (ACS) in New York in August 1991, published in "Synthesis of Microporous Materials, Extended clays and Other Microporous Solids" (1992). The teaching of these documents is hereby included in the present description. The scope of the invention also includes any type of dioctahedral 2:1 phyllosilicate containing fluorine. This fluorine can be added on synthesis or after synthesis. Any preparation method is suitable, and that described above is highly advantageous. The dioctahedral 2:1 phyllosilicates can be bridged using any technique which is known to the skilled person, in particular the bridging process developed by us and described in patents FR-A-2 720 386 and FR-A-2 720 387, the teachings of which are hereby included by reference. This process comprises at least one treatment comprising a first step in which a solution of polycations is brought into contact with the phyllosilicate to be bridged comprising exchangeable cations, to form the reaction mixture; then in a second step, exchange is carried out between the polycations and the exchangeable cations of the phyllosilicate: and finally, in a third step the product obtained is separated by filtering and washed; the treatment is characterized in that: the mass of the clay to be bridged per total solution volume is in the range 1 to 200 g/l; the second, exchange, step is carried out at a temperature which is in the range 15.degree. C. to 100.degree. C.; said second step has a duration which is in the range 1 minute to 3 hours; the separation time in the third step is in the range 20 seconds to 60 minutes per litre of solution containing the product to be separated in suspension. This bridging process can simply and rapidly introduce, for example, [A1.sub.13 O.sub.4 (OH).sub.24 (H.sub.2 O).sub.12 ].sup.7+ polycations, also known as Keggin ions, or polycations containing at least one element selected from the group formed by zirconium, titanium, molybdenum and vanadium, non limiting examples of which are: [Zr.sub.4 (OH).sub.8 (H.sub.2 O).sub.16 ].sup.8+, or [ZrOCl.sub.2 Al.sub.8 (OH).sub.20 ].sup.4+. The catalyst of the present invention can also contain a Y zeolite with faujasite structure (Zeolite Molecular Sieves: Structure, Chemistry and Uses, D. W. Breck, J Wiley & Sons, 1973). Of the Y zeolites which can be used, a stabilised Y zeolite is preferably used, which is known as ultrastable zeolite or USY, either in a form which is at least partially exchanged with metal cations, for example alkaline-earth and/or rare earth metal cations with atomic number 57 to 71 inclusive, or in the hydrogen form. An acidic zeolite HY is particularly advantageous and is characterised by different specifications: a SiO.sub.2 /Al.sub.2 O.sub.3 molar ratio which is in the range about 8 to 70, preferably in the range 12 to 40; a sodium content of less than 0.15% by weight, determined using zeolite calcined at 1100.degree. C.; a crystal parameter in the unit cell which is in the range 24.55.times.10.sup.-10 m and 24.24.times.10.sup.-10 m, preferably in the range 24.38.times.10.sup.-10 m to 24.26.times.10.sup.-10 m; a sodium take-up capacity CNa, expressed as the number of grams of Na per 100 grams of modified zeolite, neutralised then calcined, of more than about 0.85; a specific surface area (determined using the B.E.T method) of about 400 m.sup.2 /g, preferably more than 550 m.sup.2 /g, a water vapour adsorption capacity of more than about 6% at 25.degree. C. at a partial pressure of 2.6 torrs (i.e., 34.6 MPa), a pore distribution in the range 1% to 20%, preferably in the range 3% to 15%, of the pore volume contained in pores of diameters between 20.times.10.sup.-10 m and 80.times.10.sup.-10 m, the remainder of the pore volume being contained in pores with a diameter of less than 20.times.10.sup.-10 m. The catalyst of the present invention also contains at least one matrix which is normally amorphous or only slightly crystalline selected, for example, from the group formed by alumina, silica, magnesia, titanium oxide, zirconia, aluminium, titanium or zirconium phosphates, combinations of two or more of these compounds, and alumina-boron oxide combinations. The matrix is preferably selected from the group formed by silica, alumina, magnesia, silica-alumina combinations, and silica-magnesia combinations. The catalyst support of the present invention thus comprises: a) 20% to 99%, or 30% to 96%, preferably 40% to 90%, more preferably 50% to 85% by weight, of matrix (matrices); b) 1% to 80%, or 4% to 70%, preferably 10% to 60%, more preferably 15% to 50% by weight, of dioctahedral 2:1 phyllosilicate(s) synthesised in a fluoride medium and optionally bridged; c) 0 to at most 30%, or 0.1% to 30%, preferably 0 to at most 20% or 0.1% to 20%, more preferably 0 to at most 10% or 0.1% to 10% of Y zeolite(s) with faujasite structure, in the hydrogen form, preferably with the characteristics given above. The catalyst of the present invention can be prepared by any of the methods known to the skilled person. A preferred method for use in the present invention consists of grinding a dioctahedral 2:1 phyllosilicate, synthesised in a fluoride medium and optionally bridged, and optionally a Y zeolite, in a wet alumina gel for several tens of minutes, then passing the paste obtained through a die to form extrudates with a diameter which is in the range 0.4 to 4 mm. The catalyst also contains at least one catalytic element, for example a metal with a hydro-dehydrogenating function. The hydro-dehydrogenating function is provided by at least one metal or compound of a metal from group VIII such as nickel or cobalt. A combination of at least one metal or compound of a metal from group VI (in particular molybdenum or tungsten) and at least one metal or compound of a metal from group VIII (in particular cobalt or nickel) of the periodic classification of the elements can be used. The total concentration of oxides of metals from groups VI and/or VIII is in the range 1% to 40% by weight of the catalyst, preferably in the range 3% to 30%, advantageously in the range 8% to 40%, more preferably 10% to 40% and most preferably 10% to 30%, and the ratio of the metal(s) from group VI to the metal(s) from general VII is in the range 1.25 to 20, preferably in the range 2 to 10, expressed as the weight of metal oxide. Further, the catalyst can contain phosphorous. The phosphorous content, expressed as the concentration of phosphorous oxide P.sub.2 O.sub.5, is advantageously less than 15% by weight, preferably less than 10% by weight. The hydrogenating function in itself has been described above (elements from group VIII or a combination of elements from groups VI and VIII) can be introduced into the catalyst at different stages of the preparation and in different manners. It can be introduced in part only (for example with combinations of groups VI and VIII) or completely when grinding the dioctahedral 2:1 phyllosilicate synthesised in a fluoride medium and optionally bridged, with a gel of the oxide selected as the matrix. It can be introduced by one of more ion exchange operations carried out on the calcined dioctahedral 2:1 phyllosilicate based support which has been synthesised in a fluoride medium and optionally dispersed in the selected matrix, using solutions containing precursor salts of the selected metals, in particular salts of elements of group VIII. It can be introduced by one or more steps for impregnating the formed and calcined support using a solution of precursors of oxides of metals from group VIII (in particular cobalt and nickel) when the precursors of oxides of metals from group VI (in particular molybdenum or tungsten) have already been introduced when grinding the support. Finally, it can be introduced by one or more impregnation operations for a support based on a dioctahedral 2:1 phyllosilicate, synthesised in a fluoride medium and optionally bridged, and a matrix, advantageously already formed and calcined, using one or more solutions containing precursors of oxides of metals of groups VI and/or VIII, precursors of oxides of group VIII metals preferably being introduced after those of group VI or optionally at the same time as the latter. When the metal oxides are introduced in several steps for impregnating the corresponding precursor salts, an intermediate calcining step is preferably carried out on the catalyst at a temperature which is in the range 250.degree. C. to 600.degree. C. Molybdenum impregnation can be facilitated by addition of phosphoric acid to solutions of ammonium paramolybdate. The catalysts obtained are used to hydrocrack heavy cuts, and exhibit improved activity over the prior art. In addition, they have improved selectivity towards the production of very high quality middle distillates. The feeds used in the process are, for example, gas oils, vacuum distillates, vacuum gas oils, or deasphalted residues or their equivalent. Feeds containing high concentrations of N and S preferably have already been hydrotreated. Preferably, at least 80% of their volume is constituted by compounds with boiling points which are at least 350.degree. C., preferably 350.degree. C. to 580.degree. C. (i.e., corresponding to compounds containing at least 15 to 20 carbon atoms). They generally contain heteroatoms such as sulphur and nitrogen. The nitrogen content is usually in the range 1 to 5000 ppm by weight and the sulphur content is in the range 0.01% to 5% by weight. The hydrocracking conditions, such as temperature, pressure, hydrogen recycle ratio, hourly space velocity, can vary widely depending on the nature of the feed, the quality of the desired products, and the installations available to the refiner. The temperature is generally more than 230.degree. C., usually in the range 300.degree. C. to 480.degree. C., and preferably less than 450.degree. C. The pressure is greater than or equal to 2 MPa, generally more than 3 MPa, up to 10 MPa, and less than 30 MPa. The quantity of hydrogen is generally a minimum of 100 l/l of feed, usually in the range 260 to 3000 litres of hydrogen per litre of feed. The hourly space velocity is generally between 0.2 and 10 h.sup.-1. The factors which are important to the refiner are the activity and selectivity towards middle distillates. Fixed targets must be achieved under conditions which are compatible with economic reality. The refiner thus seeks to reduce the temperature, pressure, and quantity of hydrogen and to maximise the hourly space velocity. Conversion is also known to be increased by raising the temperature, but it is often to the detriment of selectivity. Selectivity towards middle distillates improves with an increase in the pressure or the quantity of hydrogen, but this is to the detriment of the economy of the process. This type of catalyst can, under conventional operating conditions, produce selectivities towards middle distillates with boiling points in the range 150.degree. C. to 380.degree. C. of more than 65%, for levels of conversion to products with boiling points of less than 380.degree. C. of more than 55% by volume. Under less severe mild hydrocracking conditions, the selectivities towards middle distillates are over 65% (and generally more than 75%) for levels of conversion of more than 30%, generally around 40-50%, and usually less than 55%. Further, under these conditions, the catalyst has remarkable stability. Finally, because of the composition of the catalyst, it can readily be regenerated. The following examples illustrate the present invention without in any way limiting its scope. |
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