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  • C01B39/02—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof; Direct preparation thereof; Preparation thereof starting from a reaction mixture containing a crystalline zeolite of another type, or from preformed reactants; After-treatment thereof
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  • C01B39/02—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof; Direct preparation thereof; Preparation thereof starting from a reaction mixture containing a crystalline zeolite of another type, or from preformed reactants; After-treatment thereof
  • C01B39/20—Faujasite type, e.g. type X or Y
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  • C01B39/02—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof; Direct preparation thereof; Preparation thereof starting from a reaction mixture containing a crystalline zeolite of another type, or from preformed reactants; After-treatment thereof
  • C01B39/20—Faujasite type, e.g. type X or Y
  • C01B39/22—Type X
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  • C01B39/02—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof; Direct preparation thereof; Preparation thereof starting from a reaction mixture containing a crystalline zeolite of another type, or from preformed reactants; After-treatment thereof
  • C01B39/46—Other types characterised by their X-ray diffraction pattern and their defined composition
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  • C01P2004/62—Submicrometer sized, i.e. from 0.1-1 micrometer
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  • C01P2006/16—Pore diameter
  • C01P2006/17—Pore diameter distribution

Definitions

• the present invention relates to the field of zeolites, especially zeolites with hierarchical porosity, and in particular zeolites with hierarchical porosity of low Si / Al molar ratio, and especially zeolites with hierarchical porosity of low Si / Al molar ratio. of structure FAU and LTA.
• Synthetic zeolites (that is to say non-natural) are of ever increasing interest in the industry, as evidenced by the many recent research work related to obtaining zeolites always more efficient, with synthetic processes always simpler, economic and easy to implement.
• hierarchical porosity zeolites are the subject of many scientific publications and patent applications.
• the process for synthesizing zeolites with hierarchical porosity with good crystallinity was described in application WO2007 / 043731, using an organosilane structuring agent.
• the product obtained after calcination comprises a zeolite network connected to a network of mesopores of a few nanometers in diameter.
• the hydrothermal resistance of this product is much better than that of mesoporous solids type MCM-41 which allows to consider applications in which involves a thermal regeneration.
• Zeolitic structure postprocessing which consists of removing atoms from the zeolite network to create mesopores; this can be done either by acid treatments which dealuminate the solid followed by a washing with sodium hydroxide which eliminates the aluminic residues formed (J. Pérez-Ramirez et al., Adv Funct Mater., (2012), 1 - 12 or by treatments that combine the action of an acid with that of a structuring agent that promotes the formation of mesopores (see WO 2013/106816).
• Hard templating method or “molding method” which consists of using a porous network (organic or inorganic) as a mold, this porous network is brought into contact with a reaction medium that can form a zeolite network by hydrothermal transformation, the crystallization of the zeolite is carried out then eliminates the mold either by calcination or by dissolution to generate mesoporosity (CJH Jacobsen, J. Am. C em. Soc., (2000), 122, 71 16-71 17).
• CJH Jacobsen J. Am. C em. Soc.
• microporous volume of these hierarchically porous zeolites is significantly lower than that of non-mesoporous zeolites
• the structuring agent modifies the growth rates of the faces of the crystals, which makes it difficult to control the size of the crystals,
• One of the objectives of the present invention is to solve at least these three major drawbacks noted for direct synthesis using an organosilane type structuring agent.
• the patent application EP2592049 proposes the synthesis of a zeolite having a very large and well organized mesoporosity, but with a marked degradation of the crystalline framework (very low microporosity). This method uses a specific structuring agent comprising three ammonium functions.
• microporous volumes are significantly lower than the microporous volumes of equivalent non mesoporous zeolites (that is to say whose mesoporous outer surface as defined below is strictly less than 40. m 2, g "1 ), which is very penalizing in applications where a high active site content is required.
• the size of the crystals is undergone and can not be modified.
• preparation methods described in the prior art seem to be difficult to industrialize especially because of the high costs they can generate, and because of the synthesis times which are even longer than the desired increase the mesoporosity.
• the document US2013 / 0183229 introduces an amount of Pluronic ® of the same order of magnitude as the amount of zeolite X, carries out long liquid channel treatments followed by several calcination treatments while the document WO2013 / 106816 introduced treatment with a halide of cetyltrimethylammonium (CTA) coupled with an acid.
• CTA cetyltrimethylammonium
• an object of the present invention is to provide hierarchically porous zeolites combining a high microporous volume, optimal purities and adjustable crystal sizes.
• Another object of the present invention is to provide an economical, simple and easily industrializable process for the preparation of said zeolites.
• the present invention relates to a zeolite with hierarchical porosity having at least the following characteristics:
• the zeolite according to the present invention is a zeolite of the FAU type, and in particular a zeolite X, MSX, LSX or an EMT type zeolite or an LTA zeolite, ie a zeolite A
• zeolite MSX Silica X medium
• zeolite LSX Low Silica X
• the characteristics mentioned above give the zeolite according to the present invention, improved properties and quite surprising and interesting, compared to only microporous zeolites or both microporous and mesoporous known from the prior art.
• the size of the crystals of the zeolite according to the present invention is expressed by their number average diameter by scanning electron microscope (SEM) observation, as indicated below.
• SEM scanning electron microscope
• the present invention also has the advantage of allowing to adjust and adjust this size of crystals, in particular according to the synthesis conditions explained below.
• the microporous volume / ⁇ ⁇ of a non-mesoporous LTA zeolite perfectly crystallized is equal to 0.30 cm 3 .
• the microporous volume ⁇ ⁇ ⁇ of a zeolite FAU NaX, Si / Al ratio between 1 and 1, 5, not mesoporous and perfectly crystallized is equal to 0.36 cm 3 .g -1 .
• the calculation of the microporous volume is carried out by applying the methods known to those skilled in the art from the nitrogen or argon adsorption isotherm by applying, as indicated below, the Dubinin-Raduskevitch equation. . And, as a reminder, the calculation of the mesoporous outer surface is measured using the Harkins and Jura equation.
• the hierarchically porous zeolites according to the invention are solids comprising a microporous network connected to a mesopore network, and thus make it possible to reconcile the properties of accessibility to the active sites of the mesoporous zeolites known from the prior art and those of maximum crystallinity and microporosity of so-called "classical" zeolites (without mesoporosity).
• the hierarchically porous zeolites of the present invention have unexpected properties and open new perspectives as to their fields of industrial applications.
• the zeolites of the present invention may be subjected to one or more cationic exchanges (for example with alkali metal or alkaline earth metal salts), as is well known to those skilled in the art and commonly performed on conventional zeolites.
• cationic exchanges for example with alkali metal or alkaline earth metal salts
• the present invention relates to the method for preparing zeolites with hierarchical porosity as just described.
• the method of the invention has the advantages of being easy to implement, easily transferable on an industrial scale, and this in particular because of the high yields of synthetic materials, the robustness of the process and its speed.
• the method for preparing the zeolite with hierarchical porosity according to the invention comprises at least the following steps:
• step b) adding to the growth gel of step a) a nucleating agent, at a temperature between 0 ° C and 60 ° C,
• step c) of adding agent (s) structurant (s) can be operated simultaneously with the steps a) and / or b) or before and / or after the steps a) and / or b).
• the structuring agent must be present in the reaction medium before step d) of crystallization.
• a latency time rest time, with or without agitation
• steps a), b), c) and d can be provided between steps a), b), c) and d).
• the growth gel comprises a homogeneous mixture of a source of silica (for example sodium silicate), a source of alumina (for example alumina trihydrate), a strong mineral base, such as for example, sodium hydroxide, potassium hydroxide, or calcium hydroxide to name only the main and most commonly used, and water.
• a source of silica for example sodium silicate
• a source of alumina for example alumina trihydrate
• a strong mineral base such as for example, sodium hydroxide, potassium hydroxide, or calcium hydroxide to name only the main and most commonly used, and water.
• the process of the present invention is characterized by the use of the seeding technique with at least one nucleating agent well known to those skilled in the art, for example chosen from a nucleating gel, a crystal, for example for example, a zeolite crystal, a mineral particle of any kind, for example kaolin, meia-kaolin, or other clay, and the like, and mixtures thereof.
• a nucleating agent well known to those skilled in the art, for example chosen from a nucleating gel, a crystal, for example for example, a zeolite crystal, a mineral particle of any kind, for example kaolin, meia-kaolin, or other clay, and the like, and mixtures thereof.
• the nucleating agent promotes the orientation of the synthesis towards the desired zeolite.
• the nucleating agent is a nucleation gel, and more preferably, said nucleating gel comprises a homogeneous mixture of a source of silica (for example sodium silicate), a source of alumina (for example alumina trihydrate), a strong mineral base, such as, for example, sodium hydroxide, potassium hydroxide, or calcium hydroxide to name only the main and most commonly used, and water.
• a source of silica for example sodium silicate
• a source of alumina for example alumina trihydrate
• a strong mineral base such as, for example, sodium hydroxide, potassium hydroxide, or calcium hydroxide to name only the main and most commonly used, and water.
• the homogeneity of the mixture can be obtained by any method well known to those skilled in the art, and for example and without limitation by means of a paddle stirrer, a mixer, or to using an Archimedean screw type mixer as described in patent EP0818418.
• the mixture is generally prepared at temperatures between 0 ° C and 60 ° C, preferably between 10 ° C and 40 ° C, and for practical and economic reasons, the mixture is prepared more preferably at temperature. ambient, for example at 25 ° C.
• the homogenization period is then generally less than 2 hours.
• the method of the present invention is further characterized by the addition to the growth gel thus obtained of a nucleating agent, and preferably a gel of nucleation according to the concept defined in US3947482.
• the added amount of nucleating agent can vary in large proportions, and the amount of nucleation gel added can generally be from 0.1% to 20%, preferably from 0.5% to 15% by weight, of more preferably between 1% and 10% by weight, inclusive, based on the weight of the growth gel.
• the nucleating agent is a zeolite crystal
• it is preferably a zeolite crystal of the same nature as the zeolite that is desired to synthesize.
• the size of the crystal can vary in large proportions, and for example is typically between 0.1 ⁇ and 10 ⁇ .
• the zeolite crystal is introduced in the form of an aqueous suspension.
• the quantity of crystals introduced can also vary in large proportions and is generally between 0.1% and 10% by weight relative to the total weight of growth gel.
• the method of the present invention is a method of direct synthesis of zeolite with hierarchical porosity, and not a method where the hierarchized porosity results from a post-treatment of an already synthesized zeolite. However, it would not be outside the scope of the invention, by operating a subsequent post-processing step of the zeolite as synthesized.
• the method of the present invention comprises an addition step in the mixture [growth gel / nucleating agent] obtained in step b) of at least one structuring agent.
• the structuring agents that can be used are of all types known to those skilled in the art and in particular those described in the application WO2007 / 043731.
• the structuring agent is advantageously chosen from organosilanes and more preferably from [3- (trimethoxysilyl) propyl] octadecyldimethylammonium chloride, [3- (trimethoxysilyl) propyl] hexadecyldimethylammonium chloride, [3- (trimethoxysilyl) propyl] dodecyldimethylammonium chloride, [3- (trimethoxysilyl) propyl] octylammonium chloride, N- [3- (trimethoxysilyl) propyl] aniline, 3- [2- (2-aminoethylamino)] ethylamino] propyltrimethoxysilane, N- [3- (trimethoxysilyl) prop
• PPDA Polymer Poly-Diallyldimethylammonium
• PVB PolyVinyl Butyral
• other oligomeric compounds known in the art for increasing the diameter of the mesopores.
• agent (s) structurant (s) can vary in large proportions and in general it is such that the molar ratio of agent (s) structuring (s) / AI 2 0 3 starting is included between 0.005 and 0.20, preferably between 0.01 and 0.15, more preferably between 0.02 and 0.08 inclusive.
• step a The addition of the structuring agent (s) is carried out with stirring, for example as indicated previously in step a), and then the mixture is subjected to a maturation step, preferably with stirring, always at the same temperature, for example at 25 ° C, for a time varying from a few minutes to several tens of minutes, typically for one hour, with stirring at 300 rpm "1 .
• step d) the reaction mixture is initiated in step d) crystallization, still under agitation, but slower, typically between 20 tr.min “1 and 100 r” 1, e.g. 50 rpm "-1 , and increasing the temperature to a value between 60 ° C and 100 ° C, for example 75 ° C.
• the time required for crystallization is generally between a few hours and several tens of hours. hours, advantageously between 8 hours and 48 hours.
• the zeolite crystals are extracted from the reaction medium by filtration, then washed with one or more suitable solvent (s), aqueous and / or organic (s), but preferably aqueous and finally dried between 50 ° C and 150 ° C, according to the usual techniques known to those skilled in the art.
• the average size of the crystals may in particular be controlled by adjusting the content of nucleating agent (nucleation gel, or crystals for example of zeolite, or other) relative to the growth gel in step b).
• nucleating agent nucleation gel, or crystals for example of zeolite, or other
• the dried crystals are then subjected to calcination, a step necessary to release both the microporosity (elimination of water) and the mesoporosity (elimination of the structuring agent).
• the calcination used to eliminate the structuring agent can be carried out according to any calcination method known to those skilled in the art.
• the calcination of the zeolite crystals comprising the structuring agent can be carried out under an oxidizing and / or inert gas scavenging, with in particular gases such as oxygen, nitrogen, air, a dry air and / or decarbonated, an air depleted oxygen, optionally dry and / or decarbonated, at a temperature or temperatures above 150 ° C, typically between 180 ° C and 800 ° C, preferably between 200 ° C and 650 ° C, for a few hours, for example between 2 and 6 hours.
• gases such as oxygen, nitrogen, air, a dry air and / or decarbonated, an air depleted oxygen, optionally dry and / or decarbonated
• cationic exchanges for example with alkali metal or alkaline earth metal salt (s)
• drying step and / or calcination (step f) it would not be outside the scope of the invention by operating one or more cationic exchanges (for example with alkali metal or alkaline earth metal salt (s)), before or after the drying step and / or calcination (step f)), according to conventional cation exchange techniques.
• the synthesis method of the invention is easy to implement and it is performed in a relatively short time, and in particular in a reduced time by a factor of at least 4, with respect to methods for the synthesis of ZPH known from the prior art which are very long, for example due to the inhibitory effect of the organosilane structurant for the nucleation and growth of the microporous zeolite network. It has been discovered, quite surprisingly, that the inhibitory effect of the structuring agent (eg TPOAC) is compensated for by the presence of the nucleating agent.
• the structuring agent eg TPOAC
• the process of the invention is more productive and less expensive because it is carried out in a single step, of relatively short duration.
• the loss on ignition is determined in an oxidizing atmosphere, by calcination of the sample in air at a temperature of 950 ° C ⁇ 25 ° C, as described in standard NF EN 196-2 (April 2006). The standard deviation of measurement is less than 0.1%.
• the volume of Dubinin-Raduskevich is determined from the measurement of the gas adsorption isotherm, such as nitrogen or argon, at its liquefaction temperature, depending on the pore opening.
• zeolite structure argon or nitrogen for LTA (previously exchanged with calcium, as described in Breck, ibid., Table 5.7, page 428) and nitrogen for FAU.
• the zeolite adsorbent Prior to adsorption, the zeolite adsorbent is degassed between 300 ° C. and 450 ° C. for a period of between 9 hours and 16 hours under vacuum (P ⁇ 6.7 ⁇ 10 -4 Pa).
• adsorption is then carried out on an ASAP 2020 Micromeritics-type apparatus, taking at least 35 measuring points at relative pressures with a ratio ⁇ / ⁇ 0 of between 0.002 and 1.
• the microporous volume is determined according to Dubinin-Raduskevitch from FIG. isotherm obtained by applying the ISO 15901 -3 (2007) standard.
• the microporous volume evaluated according to the Dubinin-Raduskevitch equation is expressed in cm 3 of liquid adsorbate per gram of zeolite. The measurement uncertainty is ⁇ 0.003 cm 3 .g "1 .
• the estimation of the number average diameter of the zeolite crystals is carried out as indicated previously by observation with a scanning electron microscope.
• a set of images is carried out at a magnification of at least 5000.
• the diameter of at least 200 crystals is then measured using a dedicated software, for example the Smile View software from the LoGraMi editor.
• the accuracy is of the order of 3%.
• the morphology of the crystals is qualified from SEM photos taken at magnification adapted to the size of the crystals.
• a line can be drawn which defines an adsorbed Y intercept which allows the microporous surface to be calculated; if the solid is not microporous the line goes through 0.
• the powder is dispersed in ethanol: 1 minute under ultrasound. One drop of the solution is deposited on a microscopy grid. The sample is allowed to dry at room temperature. The observation is made with a transmission electron microscope (FEI CM 200) at a voltage of 120 kV.
• FEI CM 200 transmission electron microscope
• magnifications obtained from x 220000 make it possible to visualize the presence of the mesopores and to estimate their diameters.
• An elemental chemical analysis of the zeolite with hierarchical porosity can be carried out according to various analytical techniques known to those skilled in the art. Among these techniques, one can quote the technique of chemical analysis by ray fluorescence X as described in standard NF EN ISO 12677: 201 1 on a wavelength dispersive spectrometer (WDXRF), for example Tiger S8 from Bruker.
• WDXRF wavelength dispersive spectrometer
• X-ray fluorescence is a non-destructive spectral technique exploiting the photoluminescence of atoms in the X-ray domain, to establish the elemental composition of a sample.
• the excitation of the atoms generally by an X-ray beam or by bombardment with electrons, generates specific radiations after return to the ground state of the atom.
• the X-ray fluorescence spectrum has the advantage of relying very little on the chemical combination of the element, which offers a precise determination, both quantitative and qualitative. A measurement uncertainty of less than 0.4% by weight is obtained conventionally after calibration for each oxide.
• each of the zeolite structures has a single diffractogram (or diffraction spectrum) defined by the positioning of the diffraction peaks and by their relative intensities.
• the zeolite crystals are spread and smoothed on a sample holder by simple mechanical compression.
• the conditions of acquisition of the diffractogram realized on the device D5000 Brucker are the following ones:
• the interpretation of the diffraction spectrum (or diffractogram) obtained is carried out with the EVA software with identification of the phases using the ICDD PDF-2 base, release 201 1 which makes it possible to highlight a phase perfectly. crystalline.
• the amount of zeolite fractions X is measured by XRD analysis. This analysis is carried out on a device of the Bruker brand, then the quantity of the zeolite fractions X is evaluated using the software TOPAS Bruker society.
• Example 1 The amount of zeolite fractions X is measured by XRD analysis. This analysis is carried out on a device of the Bruker brand, then the quantity of the zeolite fractions X is evaluated using the software TOPAS Bruker society.
• a growth gel is prepared by mixing an aluminate solution containing 19 g of hydroxide. sodium (NaOH), 128 g of alumina trihydrate ( ⁇ 2 0 3 ⁇ 3 ⁇ 2 0 containing 65.2% by weight AI 2 0 3) and 195.5 g water at 25 ° C in 25 minutes with an agitation rate of 300 tr.min "1 in a silicate solution containing 565.3 g of sodium silicate, 55.3 g of NaOH and 1997.5 g of water at 25 ° C.
• the stoichiometry of the gel growth is as follows: 3.48 Na 2 0 / AI 2 0 3 / 3.07 Si0 2/180 H 2 0.
• the homogenization of the gel growth is carried out with stirring at 300 revolutions min -1 for 25 minutes at 25 ° C.
• nucleating gel (2% by weight) of composition 12 Na 2 0 / AI 2 0 3 / 10 Si0 2/180 H 2 0 prepared in the same manner as the growth of frost, and ripened for 1 hour at 40 ° C. After 5 minutes of homogenization at 300 tr.min "1, the stirring rate is reduced to 100 r "1 and continued for 30 minutes.
• the drying is carried out in an oven at 90 ° C for 8 hours, the loss on ignition of the dried product is 23% by weight.
• the calcination of the dried product necessary to release both the microporosity (water) and the mesoporosity by eliminating the structuring agent is carried out with the following temperature profile: 30 minutes of temperature rise at 200 ° C., then 1 bearing time at 200 ° C, then 3 hours of temperature rise at 550 ° C, and finally 1.5 hours of bearing at 550 ° C.
• Example 2 The procedure is as described in Example 1, with a TPOAC / Al 2 O 3 molar ratio of 0.02. 255 g of anhydrous equivalent solid of XPH zeolite are obtained, which represents a yield of 99 mol% relative to the amount of aluminum involved.
• the Si / Al ratio of the X-ray fluorescence ZPH is 1.24.
• Example 2 The procedure is as described in Example 1, with a TPOAC / Al 2 O 3 molar ratio of 0.08. 255 g of anhydrous equivalent solid of XPH zeolite are obtained, which represents a yield of 99 mol% relative to the amount of aluminum involved.
• the Si / Al ratio of the X-ray fluorescence ZPH is 1.24.
• Example 2 The procedure is as described in Example 1, with a TPOAC / Al 2 O 3 molar ratio of 0.04, and in step b) the nucleation gel is replaced by the introduction of 1% by weight. weight (relative to the total weight of the growth gel) of zeolite X crystals (crystals with a mean diameter by volume of about 0.8 ⁇ , prepared as described in example b) of the synthesis of application WO2014 / 090771). 254 g of a solid having the same characteristics as those obtained for the solid of Example 1 are obtained. Comparison of the characteristics of the zeolite X powders with hierarchical porosity synthesized in Examples 1, 2 and 3
• the porosity characteristics are calculated from the nitrogen adsorption / desorption isotherms at the temperature of the liquid nitrogen of a previously degassed powder at room temperature. 300 ° C under vacuum. Measurements are made on an ASAP 2020 Micromeritics device.
• microporous volume (cm 3, g -1 ) is calculated according to the Dubinin-Radushkevich theory
• the mesoporous outer surface (m 2, g -1 ) is calculated from the t-plot model.
• the mesopore size distribution is calculated by the Density Functional Theory (DFT) method with the cylindrical Pore model.
• DFT Density Functional Theory
• the X-ray diffraction makes it possible to identify the crystalline phases present in the powder from the reference spectra (or diffractograms) of the various zeolite structures and to demonstrate the level of crystallinity of the solids produced as a function of the peak intensity.
• FIGS. 1a and 1b show TEM images of the reference zeolite (FIG. 1 a) and the zeolite according to the invention of example 1 (FIG. 1b) and FIG. pores (volume in micropores and volume in mesopores) as a function of pore size.
• the pore volume is determined as indicated above (measurement from the nitrogen adsorption isotherm as described in the technical section "Dubinin-Raduskevich Volume” supra).
• a growth gel is prepared by mixing an aluminate solution containing 19 g of hydroxide. of sodium (NaOH) at 128 g of alumina trihydrate (Al 2 O 3 ⁇ 3H 2 O, containing 65.2% by weight of Al 2 O 3 ) and 195.5 g of water at 25 ° C. 25 minutes with a stirring speed of 300 tr.min "1 in a silicate solution containing 565.3 g of sodium silicate, 55.3 g of NaOH and 1997.5 g of water at 25 ° C.
• the stoichiometry of the gel growth is as follows: 3.48 Na 2 0 / AI 2 0 3 / 3.07 Si0 2/180 H 2 0.
• the homogenization of the gel growth is carried out with stirring at 300 revolutions min -1 for 25 minutes at 25 ° C.
• the stirred reaction medium is maintained at 50 rpm "-1 at 25 ° C for 22 hours, then the crystallization is started.
• the stirring speed is maintained at 50 rpm "-1 , and the set point of the jacket of the reactor is set at 80 ° C. so that the reaction medium rises to 75 ° C. in 80 minutes. 72 hours of residence at 75 ° C, the reaction medium is cooled by circulating cold water in the jacket to stop crystallization.
• the solids are recovered on sintered and then washed with deionized water until neutral pH.
• the drying is carried out in an oven at 90 ° C for 8 hours, the loss on ignition of the dried product is 22% by weight.
• the calcination of the dried product necessary to release both the microporosity (water) and the mesoporosity by eliminating the structuring agent is carried out with the following temperature profile: 30 minutes of rise at 200 ° C., then 1 hour of bearing at 200 ° C, then 3 hours of rise at 550 ° C, and finally 1.5 hours of bearing at 550 ° C.
• Figure 3 shows the superposition of the diffraction spectra (diffractograms).
• the superposition of the X-ray diffraction spectra (diffractograms) shows that the intensities of the diffraction peaks obtained with the solids according to the invention (zeolite of Example 1, referenced (b) in FIG. 3) are similar to those obtained. with the reference zeolite (referenced (a) in Figure 3), regardless of the amount of structuring agent introduced.
• the method according to the invention thus makes it possible to obtain solids whose crystallinity is optimal and controlled.
• the synthesis method implemented with the use of a structuring agent, a seeding gel and / or a nucleation gel makes it possible to vary the microporous volume / mesoporous outer surface distribution in the case of zeolites with a low Si / Al ratio, typically between 1 and 1, 4, while obtaining a pure FAU (Faujasite) type zeolite, without observing any other crystalline form, and in particular without co-crystallization of P. zeolite.
• the zeolite obtained has a crystal size of between 0.5 and 1.0 ⁇ m, that is to say less than the size of the crystals of the zeolite obtained in Example 1.
• a growth gel is prepared by mixing an aluminate solution containing 300 g of sodium hydroxide. sodium (NaOH), 264 g of 85% potassium hydroxide, 169 g of alumina trihydrate (Al 2 O 3 , 3H 2 O, containing 65.2% by weight of Al 2 O 3 ) and 1200 g water at 25 ° C in 5 minutes with a speed stirring 250 tr.min "1 silicate with a solution containing 490 g of sodium silicate, 29.4 g of NaOH and 470 g of water at 25 ° C.
• the stoichiometry of the gel growth is as follows: 4.32 Na 2 0/1 85 K 2 0 / AI 2 0 3 / Si0 2 2.0 / 1 14H 2 0.
• the homogenization of the gel growth is carried out with stirring at 250 tr.min "1 for 15 minutes at 25 ° C.
• nucleating gel (0.2 wt%) of composition 12 Na 2 0 / AI 2 0 3/10 Si0 2/180 H 2 0 prepared in the same manner as the growth of frost, and ripened for 1 hour at 40 ° C. After 5 minutes of homogenization at 250 tr.min "1, the rate of agitation is reduced to 50 tr.min "1 and continued for 30 minutes.
• the solids are recovered on sintered and then washed with deionized water to neutral pH.
• the drying is carried out in an oven at 90 ° C. for 8 hours.
• the calcination of the dried product necessary to release both the microporosity (water) and the mesoporosity by eliminating the structuring agent is carried out by vacuum degassing with a gradual increase in steps of 50 ° C. to 400 ° C. C for a period of between 9 hours and 16 hours under vacuum (P ⁇ 6.7 ⁇ 10 -4 Pa).
• Diameters of the mesopores DFT 5 nm to 10 nm.
• the Si / Al molar ratio of the LSXPH determined by X-ray fluorescence is equal to 1.11.
• a growth gel is prepared by mixing a aluminate solution containing 151 g of sodium hydroxide (NaOH), 1 12.4 g of alumina trihydrate ( ⁇ 2 0 3 ⁇ 3 ⁇ 2 0 containing 65.2% by weight AI 2 0 3) and 212 g water at 35 ° C in 5 minutes with a stirring speed of 600 tr.min "1 silicate with a solution containing 321 4 g of sodium silicate and 325 g of water at 35 ° C.
• the stoichiometry of the gel growth is as follows: 3.13 Na 2 0 / AI 2 0 3/1, 92 Si0 2/68 H 2 0.
• the homogenization of the gel growth is carried out with stirring at 600 rev .min "1 for 15 minutes at 35 ° C.
• nucleating gel 1% by weight composition of 2.05 Na 2 0 / Al 2 0 3/1, 92 Si0 2/87 H 2 0 prepared in the same manner as the growth of frost, and ripened for 2 hours at 25 ° C. After 5 minutes of homogenization at 300 tr.min "1, the stirring speed was decreased to 190 tr.min "1 and continued for 30 minutes.
• the solids are recovered on sintered and then washed with deionized water to neutral pH.
• the drying is carried out in an oven at 90 ° C. for 8 hours to obtain a solid with a loss on ignition of 20%.
• the drying is carried out in an oven at 90 ° C. for 8 hours to obtain a solid with a loss on ignition of 20%.
• the calcination of the dried product necessary to release both the microporosity (water) and the mesoporosity by eliminating the structuring agent is carried out by vacuum degassing with a gradual increase in steps of 50 ° C. to 400 ° C. C for a period of between 9 hours and 16 hours under vacuum (P ⁇ 6.7 ⁇ 10 -4 Pa).
• V Dubinin-Raduskevich 0.265 cm 3 . g "1
• Diameters of the mesopores DFT 5 nm to 10 nm.
• the Si / Al molar ratio of the HPA determined by X-ray fluorescence is equal to 1.02.
• the method described in the present invention is economically viable, simple to implement on an industrial scale, with a very significant time saving compared to the syntheses described in the prior art.
• the synthesis process of the invention makes it possible to achieve quite satisfactory yields, for example with an optimum yield of 99% relative to the amount of aluminum involved and which is the element in default in the gel. of synthesis.

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