ZEOLITE NANOCRYSTAL AGGREGATES

Abstract

The present invention relates to a zeolite material in the form of FAU zeolite nanocrystal aggregates, to the method for preparing said material, to the zeolite agglomerates prepared from said material with a binder, and to the uses of said material and agglomerate as adsorbents for gas-phase or liquid-phase separation operations, and particularly in methods for separating gas or liquid flows.

Claims

1. A zeolite material in the form of FAU zeolite nanocrystal aggregates having at least the following characteristics: a Si/Al atomic ratio of between 1 and 1.4, limits inclusive, an external surface area of between 20 m.sup.2.g.sup.−1 and 80 m.sup.2.g.sup.−1, a number-mean diameter of the nanocrystals of between 50 nm and 500 nm, limits inclusive, and a number-mean aggregate size of between 0.2 μm and 10 μm.

2. The zeolite material as claimed in claim 1, wherein the zeolite nanocrystals are nanocrystals of zeolite(s) of FAU type selected from the group consisting zeolites X, MSX and LSX.

3. The zeolite material as claimed in claim 1, wherein the exchangeable sites of the zeolites are occupied by ions selected from the group consisting of hydronium, lithium, sodium, potassium, calcium, and barim ions.

4. A process for preparing the zeolite nanocrystal aggregates as claimed in claim 1, comprising using both a control agent and a step of seeding with a nucleating agent.

5. The process as claimed in claim 4, comprising at least the following steps: a) preparing a “growth” gel, by mixing a source of silica with a source of alumina, at a temperature of between 0° C. and 60° C., b) adding to the growth gel from step a) a nucleating agent, at a temperature between 0° C. and 60° C., c) adding to the reaction medium at least one control agent, d) carrying out a crystallization reaction by increasing the temperature to obtain zeolite crystals, e) filtering and washing the zeolite crystals obtained, and f) drying and calcination.

6. The process as claimed in claim 4, wherein the growth gel comprises a homogeneous mixture of a source of silica, a source of alumina, a strong mineral base, and water.

7. The process as claimed in claim 4, wherein the nucleating agent is selected from the group consisting of a nucleating gel, a crystal, a mineral particle, a clay, and also mixtures thereof.

8. The process as claimed in claim 4, wherein the amount of control agent(s) used is such that the starting control agent(s)/Al.sub.2O.sub.3 mole ratio is between 0.001 and 0.15, limits inclusive.

9. The process as claimed in claim 4, wherein the control agent is selected from the group consisting of organosilanes.

10. The process as claimed in claim 4, wherein the control agent is selected from the group consisting of N-phenylaminopropyltrimethoxysilane (SIP), aminopropyltrimethoxysilane (APTMS), isobutyltriethoxysilane (IBTES), octadecyltrimethoxysilane (ODTMS), silyl polymers, [3-(trimethoxysilyl)propyl]octadecyldimethylammonium chloride (TPOAC), and also mixtures of two or more thereof in all proportions.

11. A zeolite agglomerate comprising at least one zeolite material in the form of FAU zeolite nanocrystal aggregates as claimed in claim 1 and at least one binder, the binder content being less than or equal to 30%.

12. A method, comprising using a material comprising at least one zeolite material in the form of FAU zeolite nanocrystal aggregates as claimed in claim 1, as an adsorbent.

13. The zeolite material as claimed in claim 1, having at least the following characteristics: a Si/Al atomic ratio of between 1 and 1.4, limits inclusive, an external surface area of between 30 m.sup.2.g.sup.−1 and 80 m.sup.2.g.sup.−1, a number-mean diameter of the nanocrystals of between 50 nm and 400 nm, limits inclusive, and a number-mean aggregate size of between 0.3 μm and 10 μm.

14. A zeolite material as claimed in claim 1, having at least the following characteristics: a Si/Al atomic ratio of between 1 and 1.4, limits inclusive, an external surface area of between 40 m.sup.2.g.sup.−1 and 60 m.sup.2.g.sup.−1, a number-mean diameter of the nanocrystals of between 100 nm and 300 nm, limits inclusive, and a number-mean aggregate size of between 0.5 μm and 8 μm.

15. The zeolite material as claimed in claim 1, wherein the zeolite nanocrystals are nanocrystals of zeolite(s) of FAU X type.

16. The process as claimed in claim 4, wherein the nucleating agent is selected from the group consisting of gels, crystals and mineral particles.

17. The process as claimed in claim 4, wherein the amount of control agent(s) used is such that the starting control agent(s)/Al.sub.2O.sub.3 mole ratio is between 0.001 and 0.12, limits inclusive.

18. The process as claimed in claim 4, wherein the control agent is selected from the group consisting of N-phenylaminopropyltrimethoxysilane (SIP) and [3-(trimethoxysily)propyl]octadecyldimethylammonium chloride (TPOAC), and also mixtures of thereof in all proportions.

19. The zeolite agglomerate as claimed in claim 11, wherein the binder content is less than or equal to 20%.

20. A method, comprising using a material comprising at least one zeolite material in the form of FAU zeolite nanocrystal aggregates as claimed in claim 1, as an adsorbent, wherein the method is selected from the group consisting of processes for separating gaseous or liquid streams, gas-phase pressure-modulated adsorption processes, gas-phase or liquid-phase temperature-modulated adsorption processes, adsorption processes in a fixed bed without regeneration, and separation processes in simulated moving beds.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0147] FIG. 1 is an SEM image of the solid obtained in Example 4.

[0148] FIG. 2 is an SEM image of the solid obtained in Example 6.

[0149] FIG. 3 is a TEM image of the solid obtained in Example 3 bis.

[0150] FIG. 4 is a TEM image of the solid obtained in Example 5.

TABLE-US-00001 TABLE 1 Operating conditions of Characteristics of the FAU zeolite the syntheses nanocrystal aggregates Mole ratio External control surface Mean nano- Mean Control Type agent/Al.sub.2O.sub.3 area crystal size aggregate size V.sub.DB agent Example of seeding in gel (m.sup.2 .Math. g.sup.−1) (nm) (μm) (cm.sup.3 .Math. g.sup.−1) Diffract. Without Example 1 2% nucleating 0 — >10 0.335 X pure (comparative) gel SIP Example 2 No 0.02 25 900 few 0.326 X pure (comparative) aggregates Example 3 2% nucleating 0.04 53 400 1 0.343 X pure (invention) gel Example 3 bis 2% nucleating 0.12 52 400 1.5 0.344 X pure (invention) gel TPOAC Example 4 2% nucleating 0.01 65 300 2 0.351 X pure (invention) gel Example 5 2% nucleating 0.02 85 650 2.5 0.339 X pure (comparative) gel Example 6 1% micro- 0.014 68 200 3.5 0.347 X pure (invention) crystals SIP = N-phenylaminopropyltrimethoxysilane TPOAC = [3-(trimethoxysilyl)propyl]octadecyldimethylammonium chloride V.sub.DB (cm.sup.3 .Math. g.sup.−1) = Dubinin-Raduskevitch Volume expressed in cm.sup.3 .Math. g.sup.−1, Diffract. = Qualitative and quantitative analysis by x-ray diffraction permitting identification of the crystalline phases present in the solid analyzed X pure = zeolite FAU X with less than 2% of polluting phase.