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
  • B01J21/00—Catalysts comprising the elements, oxides, or hydroxides of magnesium, boron, aluminium, carbon, silicon, titanium, zirconium, or hafnium
  • B01J21/06—Silicon, titanium, zirconium or hafnium; Oxides or hydroxides thereof
  • B01J21/066—Zirconium or hafnium; Oxides or hydroxides thereof
• • 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
  • B01J27/00—Catalysts comprising the elements or compounds of halogens, sulfur, selenium, tellurium, phosphorus or nitrogen; Catalysts comprising carbon compounds
  • B01J27/02—Sulfur, selenium or tellurium; Compounds thereof
  • B01J27/053—Sulfates
• • 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

Definitions

• the present invention relates to an acid catalyst containing a substantial amount of mass sulfated zirconia and at least one hydrogenating transition metal, an original process for the preparation of such a catalyst, as well as the uses of this catalyst in chemical reactions for the transformation of hydrocarbons. requiring the use of an acid type catalyst.
• sulfated zirconia denotes not zirconium or stoichiometric zirconyl sulfate, but more or less sulfated zirconia (zirconium dioxide), the sulfate content of which may be lower than that of the stoichiometric compounds cited above.
• US patent 3032599 Phillips Petroleum
• US patent 3032599 is one of the first patents to describe the application of sulfated zirconia to isomerization and allation hydrocarbons: the proposed catalysts are entirely made from zirconia gel, possibly containing small amounts of a metal promoter. They are prepared by precipitation of a zirconyl salt in solution in water, by addition of base. The zirconia gel obtained is then sulphated, then activated at around 500 ° C. These catalysts do indeed have acidic catalytic properties, but they are nevertheless not very satisfactory. They indeed have a low specific surface, which may explain their relatively poor performance for isomerization reactions. In addition, these powdery catalysts are almost unusable as such in an industrial reactor.
• US patent 3132110 (Union Oil) describes the properties of a series of acid catalysts based on hydrated zirconia containing sulphate radicals, pure or preferably combined with alumina.
• the methods of preparation of these catalysts are essentially based on the decomposition of a zirconium sulphate salt in solution in water, by hydrolysis in basic medium or by thermal decomposition.
• the catalysts thus obtained are effectively active in a good number of reactions requiring the use of an acid catalyst, and have the advantage of being perfectly regenerable.
• their activity has been found to be relatively limited and these catalysts must be used at high temperatures, for example above 370 ° C. in the case of the isomerization reaction of paraffins.
• at such temperatures not only is this reaction thermodynamically disadvantaged, but, moreover, the speed of deactivation of the catalyst is accelerated by the deposition of coke on its surface.
• the patent US 4406821 proposes a catalyst consisting of a sulfated oxide deposited on an alumina support, said oxide preferably being tungsten or hafnium oxide, but can also be niobium, thallium, zirconium oxide or a mixture of these oxides.
• This catalyst is prepared by impregnating the alumina support with a solution of a salt of the chosen metal, followed by calcination at high temperature then by sulfation using an aqueous solution of sulfuric acid.
• the catalyst thus obtained does indeed have acidic properties, and it is particularly effective in the etherification reactions of phenols.
• such catalysts are not very suitable for the isomerization reaction of paraffins at low temperature, for which they seem to exhibit limited activity.
• patent application EP 908.232 describes acid catalysts based on crystallized sulfated zirconia and a hydrogenating transition metal, which are characterized by particularly high texture parameters (specific surface greater than or equal to 135 m 2 / g, pore volume greater than or equal to 0.16 cm 3 / g and average pore radius greater than or equal to 20 ⁇ ), which substantially improves their activity.
• catalysts can be of three different categories: - supported sulfated zirconia, ie a layer of sulfated zirconia is deposited on a conventional refractory oxide support, which gives the catalyst high texture parameters; Mass sulfated zirconia in intimate mixture with a structuring agent, which is another mineral oxide refractory (typically alumina, silica), which allows better control of the structure and texture of the catalyst; pure mass sulfated zirconia, prepared by drying and sulfating a hydrated zirconia gel.
• a structuring agent typically alumina, silica
• a catalyst is said to contain sulphated zirconia ⁇ mass "when it comprises zirconia crystals in its matrix (as opposed to a supported catalyst).
• the present invention relates to the last category of catalysts described above , that is to say catalysts based on pure mass sulfated zirconia.
• the Applicant has developed an original method allowing better control of the structure and texture of catalysts based on pure mass sulphated zirconia, and thus of preparing catalysts with higher porosity.
• the Applicant has discovered that, surprisingly, it is possible to substantially increase the porosity of catalysts based on pure mass sulfated zirconia by including in the process for the preparation of these catalysts a specific treatment, which consists in washing the zirconia gel using an organic polar solvent (i.e. different from water).
• This key washing step constitutes a significant improvement in the preparation methods, in that it makes it possible to obtain catalysts having a higher porosity, and which are thus more active.
• the present invention relates to a process for the preparation of a catalyst based on mass crystallized sulfated zirconia from a hydrated zirconia gel, characterized in that it comprises at least one step of washing said zirconia gel with at least minus a polar organic solvent soluble in water.
• this solvent has a solubility in water greater than or equal to 5 g / 100 ml.
• at least 5 g of solvent can be dissolved in 100 ml of water, at 23 ° C and under atmospheric pressure (760 mm Hg). Even more preferably, this solvent and water are miscible in all proportions.
• this solvent has a boiling point less than or equal to that of water, i.e. less than or equal to 100 ° C under atmospheric pressure (760 mm Hg)).
• the zirconia gel is washed at least once with the solvent.
• at least three successive washes are carried out, and even more preferably at least five successive washes.
• the preparation process according to the invention advantageously comprises the following steps: a) adding a basic solution to a solution of a zirconium salt so as to cause precipitation of a gel • hydrated zirconia, b) filtration zirconia gel, c) washing, at least once, of the zirconia gel with at least one polar organic solvent soluble in water, d) drying the resulting solid, e) sulfation of the solid, f) shaping the solid, g) deposition of a hydrogenating transition metal, h) final calcination, steps (f) of shaping and / or (g) deposition of the hydrogenating transition metal can be carried out before or after step ( e) sulphation, but before stage (h) of final calcination.
• stage (d) which is the key stage of washing the precipitate of zirconia hydrated with a polar organic solvent soluble in water.
• the zirconium salt used in step (a) can advantageously be chosen from the group consisting of nitrate, chloride, acetate, formate, zirconium and zirconyl oxalate as well as zirconium propylate and butylate.
• the basic solution used in step (a) can be any solution which makes it possible to carry out the precipitation of a hydrated oxide from a solution of a precursor salt of said oxide by increasing the pH. It may for example be an ammonia solution or any other base known to those skilled in the art.
• Step (e) of sulfation of the catalyst is carried out by impregnating the solid with a sulfating agent, then drying.
• the sulfating agent can be liquid, gaseous or in solution; it is possible to use, for example, pure sulfuric acid or in solution, an aqueous solution of ammonium sulphate, or any other precursor of sulphate ions. To achieve this sulfation, one can use any impregnation technique known to those skilled in the art.
• the catalyst shaping step (f) makes it possible to agglomerate the catalyst powder in the form of particles (beads, extrudates or pellets for example), in order to allow the direct use of this catalyst in an industrial reactor.
• a binder alumina xerogel or any other industrial binder
• the catalyst comprises from 5 to 50% by weight of binder and, preferably, from 10 to 30% by weight.
• the binder is advantageously chosen from among the aluminas, silicas, silica-aluminas, aluminosilicates, clays and mixtures of these materials.
• the step (g) of depositing the hydrogenating transition metal is advantageously carried out by impregnation of the solid by means of a solution of a compound of this hydrogenating transition metal, followed by a drying step.
• this metal is platinum
• the impregnation step is carried out using a solution of a platinum compound which can be chosen from the group consisting of chloroplatinic acid and complex platinum compounds.
• a first calcination of the catalyst is preferably carried out at a temperature greater than or equal to 550 ° C.
• the first calcination involved in the preparation method according to the invention (whether carried out immediately after the shaping step (f) or at the end of the preparation method (step (h)), must take place at a sufficiently high temperature, ie greater than or equal to 550 ° C. This is necessary for obtaining a zirconia having an adequate crystalline structure
• the process according to the present invention makes it possible to easily obtain catalysts based on pure mass sulphated zirconia in crystallized form, which have particularly high texture parameters (specific surface, pore volume, average pore radius).
• the invention also relates to the improved catalysts capable of being obtained by the process which is the subject of the present invention.
• catalysts contain at least 50% and preferably at least 70% of mass crystallized sulphated zirconia, and have the following properties: a specific surface greater than or equal to 150 m 2 / g, a volume of pores greater than or equal to 0.25 cm 3 / g and an average pore radius greater than or equal to 30 A (30.10 -10m).
• the zirconia (zirconium dioxide) is partially or completely sulfated.
• the sulphate content is less than the stoichiometric quantities: the sulfur content in the form of sulphate is preferably between 1% and 10% by weight, relative to the weight of zirconia, and, more preferably, between 1% and 5% in weight .
• the sulphated zirconia which it contains must be in crystallized form, that is to say that it must not be in amorphous form.
• the preferred crystal structures are quadratic and monoclinic type structures.
• the crystal structure of zirconia is determined, in a well known manner, by X-ray diffraction.
• a hydrogenating transition metal is necessary for the stability of the catalytic activity of the catalyst according to the invention.
• This hydrogenating transition metal is preferably an element of group VIII of the Periodic Table of the Elements and, in particular, an element of the group constituted by nickel, platinum, ruthenium, rhodium, palladium, osmium and iridium, platinum being particularly preferred.
• the crystal structure of zirconia is not significantly affected by the presence of this hydrogenating transition metal.
• the acid catalyst according to the invention is of the solid type. It can be in all the forms to which a person skilled in the art usually uses for the implementation of solid catalysts and, in particular, in the form of particles such as beads, extrudates, pellets. It has an apparent filling density preferably of between 0.5 and 3.
• the catalysts prepared by the process which is the subject of the present invention can be used in any chemical reaction for the transformation of hydrocarbons requiring the use of an acid catalyst, or even superacid. These catalysts are particularly efficient for isomerization reactions of linear paraffins into branched paraffins at a temperature below 200 ° C.
• a temperature between 20 ° C and 200 ° C (preferably between 50 ° C and 150 ° C)
• a pressure between 5.10 5 and 100.10 5 Pa (preferably between 20.10 5 and 60.10 5 Pa)
• a hydrogen / hydrocarbons to convert, H 2 / HC molecular ratio between 1 and 20 (preferably between 5 and 15).
• the catalysts prepared by the process according to the invention can be stored or loaded in a reactor without special precautions. However, it is preferable to subject them to calcination at high temperature in a dry atmosphere, before using them.
• Catalyst A no washing with organic solvent of the zirconia gel.
• the zirconium hydroxide gel is precipitated by adding 17 ml of a 28% ammonia solution, still with stirring. The final pH is 8.5. After filtration on a Buchner filter and washing with water to pH 7, it is filtered, then the gel is dried overnight at 120 ° C.
• the shaping is carried out after crushing of the whole of the solid and mixing with 3.45 g of alumina type Pural SB and 6.9 ml of distilled water in a syringe-extruder (2 mm in diameter).
• platinum is deposited by statically impregnating 12.3 g of this solid with a solution consisting of the mixture of 0.248 g of a 25% Pt chloroplatinic acid solution and 3.8 ml of water. distilled (impregnation with pore volume).
• the solid is finally dried at 120 ° C overnight and then calcined at 480 ° C for 4 hours.
• Catalyst B (according to the invention, with washing with acetone of the zirconia gel).
• the mixture is then filtered on a Buchner filter and washed with water until pH 7.
• the gel is washed with acetone: it is transferred to a beaker, in which it is dispersed in 350 ml of acetone.
• the mixture is stirred for 15 minutes, then the gel is filtered on a Buchner filter.
• After a second acetone wash carried out under the same conditions, the gel is dried overnight at 120 ° C. 13.85 g of solid are obtained.
• Sulphation is carried out by adding 85 ml of 1 N sulfuric acid to 13.65 g of the solid, and maintaining static contact for 15 minutes. We then spin on Buchner, then dry overnight at 120 ° C.
• the shaping is carried out after grinding of 15.20 g of the solid and mixing with 3.80 g of alumina type Pural SB and 16 ml of distilled water in a syringe-extruder (1.8 mm in diameter). After drying again overnight at 120 ° C, the extrudates are calcined at 650 ° C for 2 hours.
• the amount of material recovered is 14 g.
• platinum is deposited by statically impregnating 12.5 g of this solid with a solution prepared as follows: to 0.252 g of a 25% Pt chloroplatinic acid solution, water is added distilled to obtain 6.9 ml of solution. The pore volume impregnation is then carried out.
• the solid is finally dried at 120 ° C overnight and then calcined at 480 ° C for 4 hours.
• Catalyst C (according to the invention, with ethanol washing of the zirconia gel).
• the zirconium hydroxide gel is precipitated by adding 50 ml of a 28% ammonia solution, always under agitation.
• the final pH is 9.5.
• the mixture is then filtered, and washed with water in a Buchner filter until pH 7.
• the gel is then washed with methanol: it is rinsed in the filter with 50 ml of methanol, then transferred to a beaker in which it is dispersed in 600 ml of methanol, with stirring at room temperature, then filtered again. This washing (dispersion then filtration) is repeated five times.
• the gel is then dried overnight at 60 ° C.
• Sulphation is carried out by adding 198 ml of 0.5 M sulfuric acid to 30.44 g of gel, and imposing static contact for 15 minutes.
• the gel is then filtered on a Buchner filter, in which it is rinsed with 90 ml of 0.5 M sulfuric acid, then it is dried overnight at 120 ° C.
• the shaping is carried out in a syringe-extruder (1.5 mm in diameter), after grinding the 30.44 g of solid, and mixing with 7.61 g of alumina type Pural SB and 29 ml of distilled water . After drying again overnight at 120 ° C, the extrudates are calcined at 650 ° C for 3 hours. Finally, platinum is deposited by impregnation with a pore volume so as to obtain a final content of 0.5% by weight of platinum deposited on the catalyst. For this, 23.50 g of extrudates are impregnated with 8.23 ml of an aqueous solution of chloroplatinic acid at 5.32% by weight of Pt.
• the solid is finally dried at 120 ° C overnight and then calcined at 480 ° C for 4 hours.
• Catalyst D (according to the invention, with ethanol washing of the zirconia gel).
• Sulphation is carried out by adding 92 ml of 1 N sulfuric acid to 14.20 g of this gel, and imposing a contact for 15 minutes with stirring. We then spin on Buchner, then dry overnight at 120 ° C.
• the shaping is carried out after grinding of 12.88 g of the solid and mixing with 3.22 g of alumina type Pural SB and 9.9 ml of distilled water in a syringe-extruder (1.5 mm in diameter).
• the extrudates are calcined at 650 ° C for 2 hours.
• the amount of material recovered is 11.82 g.
• platinum is deposited by statically impregnating the 11.82 g of solid with a solution prepared as follows: to 0.236 g of a 25% Pt chloroplatinic acid solution, water is added distilled to obtain 4.5 ml of solution. The pore volume impregnation is then carried out. The solid is finally dried at 120 ° C overnight and then calcined at 480 ° C for 4 hours.
• solubility of ethanol in water is greater than 10 g / 100 ml at 23 ° C and atmospheric pressure.
• Table I below illustrates the properties of the catalyst samples obtained according to the preparation methods detailed above.
• the sulfated zirconia has a quadratic crystal structure. This structure was determined by X-ray diffraction.
• S, Vp and Rp respectively denote the specific surface, the pore volume and the average pore radius of the catalyst. As indicated above, these characteristics were determined using the so-called B.E.T. (Brunauer, Emmett, Teller), by nitrogen adsorption, as described in the work by S. Lowell entitled "Po der Surface Area and Porosity", Society of Petroleum Engineers Advanced Technology Series (1984).
• the specific surface S is deduced from the linear transform B.E.T.
• the catalyst is activated in situ under a stream of hydrogen, gradually increasing the reactor temperature from room temperature to 145 ° C, then maintaining the temperature at this latter value for two hours before start injecting the charge.
• samples B to D (in accordance with the invention) was determined in the isomerization reaction of a complex charge close to industrial charges, of the following composition:
• the catalyst is activated in situ under a stream of hydrogen, gradually increasing the reactor temperature from room temperature to 145 ° C, then maintaining the temperature at this latter value for one hour before start injecting the charge.
• TIN ° 100 + 2 ⁇ 100 nCS + eoCS + isoCS 2.2 DMB + 2.3 DMB + 2MP + 3MP + nC ⁇
• - isoC5 content by weight of the effluents in iso-pentane
• - nC5 content by weight of the effluents in normal-pentane
• - 2.3DMB content by weight of the effluents in 2,3 dimethyl butane
• - 2MP content by weight of the effluents in 2 methyl-pentane
• the TIN in fact corresponds to the rate of highly branched paraffins in the isomerization test effluents. It is perfectly representative of the isomerizing activity of the catalyst tested.
• Table III illustrates the excellent performance of the catalysts according to the invention, under industrial type conditions.
• the additional properties provided by the catalysts according to the invention are considerable (increased stability, ease of handling, no corrosive dopes to be injected, regenerability, etc.), which makes their use particularly advantageous in reactions involving an acid or even superacid catalyst.

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• 2000
  • 2000-07-10 US US09/613,585 patent/US6448198B1/en not_active Expired - Fee Related
• 2001
  • 2001-07-10 CA CA002415405A patent/CA2415405A1/fr not_active Abandoned
  • 2001-07-10 WO PCT/FR2001/002217 patent/WO2002004110A2/fr active Application Filing
  • 2001-07-10 EP EP01951786A patent/EP1299187A2/de not_active Withdrawn
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