Zeolite material based on mesoporous zeolite

Abstract

The present invention relates to zeolite materials in the form of agglomerates comprising at least one mesoporous zeolite and having both the characteristics of mesoporous zeolites, the properties associated with microporosity and the mechanical properties of zeolite agglomerates without mesoporous zeolite. The invention also relates to the process for preparing the said zeolite materials in the form of agglomerates.

Claims

1. An agglomerated zeolite material comprising at least one mesoporous zeolite, wherein the agglomerated zeolite material has: (1) a total zeolite content of at least 70% by weight relative to the total weight of the agglomerated zeolite material, (2) a content of mesoporous zeolite of greater than or equal to 30% relative to the total weight of the agglomerated zeolite material, (3) a binder content, after calcinations performed at 950 C. for 1 hour, of less than or equal to 30% relative to the total weight of the agglomerated zeolite material, (4) a mean volume diameter (D50), or a length (largest dimension when the material is not spherical) of less than or equal to 7 mm, and either (a) a bulk crushing strength (BCS) measured according to standard ASTM 7084-04 of between 0.5 MPa and 3 MPa, for a material with a mean volume diameter (D50), or a length (largest dimension when the material is not spherical), of less than 1 mm, limits inclusive, or (b) a grain crushing strength, measured according to standards ASTM D 4179 (2011) and ASTM D 6175 (2013), of 0.5 daN to 30 daN, for a material with a mean volume diameter (D50), or a length (largest dimension when the material is not spherical), of greater than or equal to 1 mm, limits inclusive, wherein the mesoporous zeolite has a mesoporous outer surface area of between 40 m.sup.2.Math.g.sup.1 and 400 m.sup.2.Math.g.sup.1 as defined by the t-plot method.

2. The agglomerated zeolite material of claim 1, further comprising one or more non-mesoporous zeolites.

3. The agglomerated zeolite material of claim 1, which has an apparent mass per unit volume of 0.4 g.Math.cm.sup.3 to 1 g.Math.cm.sup.3.

4. The agglomerated zeolite material of claim 1, wherein the mesoporous zeolite is selected from the group consisting of mesoporous zeolites of LTA, EMT and FAU structure, and wherein the mesoporous zeolite has an Si/Al atomic ratio of 1 to 1.4.

5. The agglomerated zeolite material of claim 1, in which zeolite crystals are agglomerated with a binder comprising a clay or a mixture of clays selected from the group consisting of kaolins, kaolinites, nacrites, dickites, halloysites, attapulgites, sepiolites, montmorillonites, bentonites, illites, metakaolins, and mixtures thereof.

6. The agglomerated zeolite material of claim 1, which has both the characteristics of mesoporous zeolites, but also the mechanical properties of conventional zeolite agglomerates in which the zeolite is non-mesoporous.

7. The agglomerated zeolite material of claim 1, wherein the agglomerated zeolite material has a total zeolite content of at least 80% by weight relative to the total weight of the agglomerated zeolite material.

8. The agglomerated zeolite material of claim 1, wherein the agglomerated zeolite material has a content of mesoporous zeolite greater than or equal to 70% by weight relative to the total weight of the agglomerated zeolite material.

9. The agglomerated zeolite material of claim 1, wherein the agglomerated zeolite material has a content of mesoporous zeolite greater than or equal to 90% by weight relative to the total weight of the agglomerated zeolite material.

10. The agglomerated zeolite material of claim 1, wherein the agglomerated zeolite material has a binder content, after calcinations performed at 950 C. for 1 hour, of less than or equal to 20% relative to the total weight of the agglomerated zeolite material.

11. The agglomerated zeolite material of claim 1, wherein the agglomerated zeolite material has a binder content, after calcinations performed at 950 C. for 1 hour, of less than or equal to 10% relative to the total weight of the agglomerated zeolite material.

12. The agglomerated zeolite material of claim 1, wherein the agglomerated zeolite material has a mean volume diameter (D50), or a length (largest dimension when the material is not spherical) of 1 mm to 2.5 mm.

13. The agglomerated zeolite material of claim 1, wherein the agglomerated zeolite material has a total zeolite content of at least 90% by weight relative to the total weight of the agglomerated zeolite material and a content of mesoporous zeolite of greater than or equal to 90% by weight relative to the total weight of the agglomerated zeolite material.

14. The agglomerated zeolite material of claim 1, wherein the mesoporous zeolite is in the form of crystals having a mean numerical diameter of less than 20 m as measured with a scanning electron microscope.

15. The agglomerated zeolite material of claim 1, wherein the mesoporous zeolite has a mesoporous outer surface area of between 60 m.sup.2.Math.g.sup.1 and 200 m.sup.2.Math.g.sup.1 as defined by the t-plot method.

16. The agglomerated zeolite material of claim 1, which has (4) a mean volume diameter (D50), or a length (largest dimension when the material is not spherical) of 1 mm to 7 mm.

17. A process for preparing the agglomerated zeolite material of claim 1, comprising: (a) obtaining an agglomerated material by agglomerating crystals of at least one mesoporous zeolite with a number-average diameter of between 0.1 m and 20 m, with an Si/Al atomic ratio of 1 to 1.4, and with a mesopore outer surface area, defined by the t-plot method, of 40 m.sup.2.Math.g.sup.1 to 400 m.sup.2.Math.g.sup.1, with a binder comprising at least 80% clay or a mixture of clays, which are optionally zeolitizable, and with up to 5% of additives, and with an amount of water that allows the shaping of the agglomerated material; (b) drying the agglomerated material from a) at a temperature of between 50 C. and 150 C. to obtain dried agglomerates; (c) calcining the dried agglomerates from b) with flushing with an oxidizing and/or inert gas, which is optionally dried and/or decarbonated, at a temperature above 150 C. to obtain calcined agglomerates; (d) optionally zeolitizing the binder by placing the calcined agglomerates obtained in c) in contact with an alkaline basic solution to obtain alkaline basic solution-treated agglomerates; (e) optionally cation exchanging the calcined agglomerates from c) or the alkaline basic solution-treated agglomerates from d) by placing in contact with a solution of at least one alkali metal or alkaline-earth metal salt; (f) washing and drying the agglomerates obtained in d) or e) at a temperature of between 50 C. and 150 C. to obtain washed and dried agglomerates, and (g) producing the agglomerated zeolite material by activating the washed and dried agglomerates obtained in f) under the conditions described in c).

18. The process of claim 17, wherein in a), agglomeration of crystals of a zeolite prepared in the presence of a sacrificial template is performed.

19. The process of claim 18, wherein the sacrificial template is selected from the group consisting of organosilane compounds and organosilane oligomers.

20. The process of claim 19, wherein the removal of the sacrificial template is performed by calcining the zeolite crystals before the agglomeration a).

21. The process of claim 19, wherein the removal of the sacrificial template is performed by calcining the zeolite crystals concomitantly with c).

22. An agglomerated zeolite material comprising at least one mesoporous zeolite, wherein the agglomerated zeolite material has: (1) a total zeolite content of at least 80% by weight relative to the total weight of the agglomerated zeolite material, (2) a content of mesoporous zeolite of greater than or equal to 50% relative to the total weight of the agglomerated zeolite material, (3) a binder content, after calcinations performed at 950 C. for 1 hour, of less than or equal to 20% relative to the total weight of the agglomerated zeolite material, (4) a mean volume diameter (D50), or a length (largest dimension when the material is not spherical) of between 0.05 mm and 7 mm, limits inclusive, and either (a) a bulk crushing strength (BCS) measured according to standard ASTM 7084-04 of between 0.75 MPa and 2.5 MPa, for a material with a mean volume diameter (D50), or a length (largest dimension when the material is not spherical), of less than 1 mm, limits inclusive, or (b) a grain crushing strength, measured according to standards ASTM D 4179 (2011) and ASTM D 6175 (2013), of between 1 daN and 20 daN, for a material with a mean volume diameter (D50), or a length (largest dimension when the material is not spherical), of greater than or equal to 1 mm, limits inclusive, wherein the mesoporous zeolite has a mesoporous outer surface area of between 40 m.sup.2.Math.g.sup.1 and 400 m.sup.2.Math.g.sup.1 as defined by the t-plot method.

23. The agglomerated zeolite material of claim 22, which has (4) a mean volume diameter (D50), or a length (largest dimension when the material is not spherical) of 1 mm to 7 mm, limits inclusive.

24. The agglomerated zeolite material of claim 22, wherein the mesoporous zeolite has a mesoporous outer surface area of between 60 m.sup.2.Math.g.sup.1 and 200 m.sup.2.Math.g.sup.1 as defined by the t-plot method.

25. An agglomerated zeolite material comprising at least one mesoporous zeolite, wherein the agglomerated zeolite material has: (1) a total zeolite content of at least 90% by weight relative to the total weight of the agglomerated zeolite material, (2) a content of mesoporous zeolite of greater than or equal to 80% relative to the total weight of the agglomerated zeolite material, (3) a binder content, after calcinations performed at 950 C. for 1 hour, of less than or equal to 10% relative to the total weight of the agglomerated zeolite material, (4) a mean volume diameter (D50), or a length (largest dimension when the material is not spherical) of between 0.2 mm and 5 mm, limits inclusive, limits inclusive, and either (a) a bulk crushing strength (BCS) measured according to standard ASTM 7084-04 of between 0.75 MPa and 2.5 MPa, for a material with a mean volume diameter (D50), or a length (largest dimension when the material is not spherical), of less than 1 mm, limits inclusive, or (b) a grain crushing strength, measured according to standards ASTM D 4179 (2011) and ASTM D 6175 (2013), of between 1 daN and 20 daN, for a material with a mean volume diameter (D50), or a length (largest dimension when the material is not spherical), of greater than or equal to 1 mm, limits inclusive, wherein the mesoporous zeolite has a mesoporous outer surface area of between 40 m.sup.2.Math.g.sup.1 and 400 m.sup.2.Math.g.sup.1 as defined by the t-plot method.

26. The agglomerated zeolite material of claim 25, which has (4) a mean volume diameter (D50), or a length (largest dimension when the material is not spherical) of 1 mm to 5 mm, limits inclusive.

27. The agglomerated zeolite material of claim 25, wherein the mesoporous zeolite has a mesoporous outer surface area of between 60 m.sup.2.Math.g.sup.1 and 200 m.sup.2.Math.g.sup.1 as defined by the t-plot method.

Description

BRIEF DESCRIPTION OF THE FIGURES

(1) FIGS. 1a and 1b show TEM images obtained at a magnification of 220 000 of a reference adsorbent (FIG. 1a) and of the adsorbent according to the invention (FIG. 1b).

(2) The image of FIG. 1b makes it possible to visualize the presence of the mesopores and to estimate their diameters.

(3) Particle Size of the Crystals:

(4) The estimation of the number-average diameter of the mesoporous zeolite crystals used in step a) and of the zeolite crystals contained in the agglomerates is performed as indicated previously by observation with a scanning electron microscope (SEM).

(5) In order to estimate the size of the zeolite crystals on the samples, a set of images is taken at a magnification of at least 5000. The diameter of at least 200 crystals is then measured using dedicated software, for example the Smile View software from the editor LoGraMi. The accuracy is about 3%.

(6) Bulk Crushing Strength:

(7) The crushing strength of a bed of zeolite adsorbents as described in the present invention is characterized according to the Shell method series SMS1471-74 (Shell Method Series SMS1471-74 Determination of Bulk Crushing Strength of Catalysts. Compression-Sieve Method), combined with the BCS Tester machine sold by the company Vinci Technologies. This method, originally intended for characterizing catalysts between 3 mm and 6 mm in size, is based on the use of a 425 m screen which makes it possible especially to separate the fines created during the crushing. The use of a 425 m screen remains suitable for particles with a diameter of greater than 1.6 mm, but must be adapted according to the particle size of the agglomerates that it is desired to characterize.

(8) Grain Crushing Strength:

(9) The mechanical grain crushing strengths are determined using a Grain Crushing Strength machine sold by Vinci Technologies, according to standards ASTM D 4179 and D 6175.

(10) Measurement of the Si/Al Ratio:

(11) The agglomerated zeolite material of the invention was evaluated as regards the Si/Al ratio by elemental chemical analysis of the said agglomerated zeolite material, and more precisely by X-ray fluorescence chemical analysis as described in standard NF EN ISO 12677 (2011) on a wavelength dispersive spectrometer (WDXRF), for example the Tiger S8 machine from the company Broker. The X-ray fluorescence spectrum has the advantage of being very little dependent on the chemical combination of the element, which offers precise determination, both quantitatively and qualitatively.

(12) A measurement uncertainty of less than 0.4% by weight is conventionally obtained after calibration for each oxide, inter alia for SiO.sub.2 and Al.sub.2O.sub.3. The measurement uncertainty of the Si/Al atomic ratio is 5%.

EXAMPLE 1

Synthesis of Mesoporous Zeolite of Type X with Addition of Nucleation Gel and of Growth Gel with a TPOAC/Al2O3 Ratio=0.04

(13) a) Preparation of the Growth Gel in a Stirred Reactor with an Archimedean Screw at 300 rpm.

(14) A growth gel is prepared in a stainless-steel reactor equipped with a heating jacket, a temperature probe and a stirrer, by mixing an aluminate solution containing 119 g of sodium hydroxide (NaOH), 128 g of alumina trihydrate (Al.sub.2O.sub.3.3H.sub.2O, containing 65.2% by weight of Al.sub.2O.sub.3) and 195.5 g of water at 25 C. for 25 minutes with a stirring speed of 300 rpm 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.

(15) The stoichiometry of the growth gel is as follows: 3.48 Na.sub.2O/Al.sub.2O.sub.3/3.07 SiO.sub.2/180 H.sub.2O. Homogenization of the growth gel is performed with stirring at 300 rpm for 25 minutes at 25 C.

(16) b) Addition of the Nucleation Gel

(17) 61.2 g of nucleation gel (i.e. 2% by weight) of composition 12 Na.sub.2O/Al.sub.2O.sub.3/10 SiO.sub.2/180 H.sub.2O prepared in the same manner as for the growth gel, and matured for 1 hour at 40 C., are added to the growth gel at 25 C. with stirring at 300 rpm. After homogenization for 5 minutes at 300 rpm, the stirring speed is reduced to 100 rpm and stirring is continued for 30 minutes.

(18) c) Introduction of the Structuring Agent into the Reaction Medium

(19) 27.3 g of a 60% solution of TPOAC in methanol (MeOH) are introduced into the reaction medium with a stirring speed of 300 rpm (TPOAC/Al.sub.2O.sub.3 mole ratio=0.04). A maturation step is performed at 25 C. for 1 hour at 300 rpm before starting the crystallization.

(20) d) Crystallization

(21) The stirring speed is lowered to 50 rpm and the nominal temperature of the reactor jacket is set at 80 C. so that the temperature of the reaction medium rises to 75 C. over 80 minutes. After a steady stage at 75 C. for 22 hours, the reaction medium is cooled by circulating cold water through the jacket to stop the crystallization.

(22) e) Filtration/Washing

(23) The solids are recovered on a sinter and then washed with deionized water to neutral pH.

(24) f) Drying/Calcination

(25) In order to characterize the product, drying is performed in an oven at 90 C. for 8 hours, and the loss on ignition of the dried product is 23% by weight.

(26) The calcination of the dried product necessary to release both the microporosity (water) and the mesoporosity by removing the structuring agent is performed with the following temperature profile: 30 minutes of temperature increase to 200 C., then 1 hour at a steady stage of 200 C., then 3 hours of temperature increase to 550 C., and finally 1.5 hours of steady stage at 550 C.

(27) 255 g of anhydrous equivalent solid of zeolite XPH are thus obtained; which represents a yield of 99 mol % relative to the amount of aluminium engaged. The Si/Al ratio of the ZPH determined by X-ray fluorescence is equal to 1.24.

(28) For comparative purposes for the preparation of an agglomerated zeolite material, a non-mesoporous commercial zeolite with an Si/Al atomic ratio equal to 1.25 is used. This reference zeolite is, for example, Siliporite G5 AP, sold by the company CECA.

(29) The characteristics of the mesoporous zeolite X prepared in this Example 1 and the characteristics of the reference zeolite indicated above are collated in Table 1 below:

(30) TABLE-US-00001 TABLE 1 Non- Mesoporous mesoporous zeolite X Reference zeolite X (Example 1) Synthesis TPOAC/Al.sub.2O.sub.3 mole ratio 0.04 Synthesis time (h) 24 Nitrogen Micropore volume (cm.sup.3/g) 0.342 0.335 adsorption Mesopore outer surface 35 105 isotherm area (m.sup.2/g) at 77 K Mesopore size (nm) 5 to 10 XRD spectrum Crystalline phase Pure X Pure X (diffractogram) Crystallinity X (%) 100 100 SEM Crystal size (m) 1.5 1 to 3

(31) The size distribution of the mesopores is characterized by the Density Functional Theory (DFT) method with the cylindrical pore model. The percentage of crystallinity is calculated by means of the TOPAS software using the base ICDD PDF-2, release 2011.

EXAMPLE 2

Preparation of Mesoporous Zeolite X Agglomerates (According to the Invention)

(32) In the text hereinbelow, the masses given are expressed as anhydrous equivalent.

(33) A homogeneous mixture consisting of 1600 g of mesoporous zeolite X crystals obtained in Example 1, 350 g of kaolin, 130 g of colloidal silica sold under the trade name Klebosol 30 (containing 30% by weight of SiO.sub.2 and 0.5% of Na.sub.2O) and also an amount of water which allows extrusion of the mixture, is prepared. The loss on ignition of the pulp before extrusion is 44%.

(34) Extrudates 1.6 mm in diameter are formed. The extrudates are dried overnight in a ventilated oven at 80 C. They are then calcined for 2 hours at 550 C. under a flush of nitrogen, and then for 2 hours at 550 C. under a flush of dry decarbonated air.

(35) The mechanical grain crushing strength of the mesoporous zeolite X extrudates is 2.6 daN. Their apparent mass per unit volume is 0.64 g/cm.sup.3.

EXAMPLE 3

Preparation of Non-Mesoporous Zeolite X Agglomerates (Comparative)

(36) The operations of Example 2 are repeated in an identical manner, replacing the mesoporous zeolite X with the reference non-mesoporous zeolite X. The mechanical grain crushing strength of the reference non-mesoporous zeolite X extrudates is 2.5 daN. Their apparent mass per unit volume is 0.66 g/cm.sup.3.

(37) It is thus observed that the agglomerated zeolite material according to the invention comprising a mesoporous zeolite X has mechanical properties and an apparent density that are entirely comparable to those of an agglomerated zeolite material comprising a non-mesoporous zeolite.

(38) It is thus entirely noteworthy that the present invention provides agglomerated zeolite materials combining both the properties of mesoporous zeolites, the properties associated with the microporosity and the mechanical properties of the zeolite agglomerates known hitherto. It is thus possible to envisage without problem the use of the agglomerated zeolite materials of the invention in all fields of industrial application such as catalysis, separation, adsorption and the like.

EXAMPLE 4

Comparison of the Agglomerates of Examples 2 and 3 Relative to an Agglomerate of the Prior Art

(39) The mesoporous zeolite obtained by post-treatment of a non-mesoporous zeolite X, described in patent application WO 2013/106 816 (PCT/US 2013/021 420), in Example 4, Table 4, last line of the table, is used for this comparative study.

(40) An agglomerate is prepared from this zeolite NaX according to the procedure described in Example 2 above.

(41) The results of the comparative analysis are presented in Table 2 below:

(42) TABLE-US-00002 TABLE 2 Nitrogen adsorption XRD spectrum isotherm at 77 K (diffractogram) Micropore Mesopore outer Crystal- Crystal- volume surface area line linity Agglomerate (cm.sup.3/g) (m.sup.2/g) phase (%) Example 2 0.279 108 X 100% (according to the invention) Example 3 0.277 37 X 100% (comparative) According to Table 4 of 0.170 90 X 46% WO 2013/106 816 (PCT/US 2013/021 420), (comparative)

(43) The percentage of crystallinity is calculated with the TOPAS software using the base ICDD PDF-2, release 2011.

(44) The agglomerates according to the invention have micropore volumes that are markedly greater than those of the prior art and at least equivalent mesopore outer surface areas. These results show that the agglomerates comprising a zeolite whose mesoporosity has been obtained by post-treatment have markedly less efficient porosity characteristics than the agglomerates prepared according to the invention.