ZEOLITE ADSORBENTS HAVING A HIGH EXTERNAL SURFACE AREA AND USES THEREOF

Abstract

The present invention concerns the use, for gas separation and/or gas drying, of at least one zeolite adsorbent material comprising at least one type A zeolite, said adsorbent having an external surface area greater than 20 m.sup.2.g.sup.1, a non-zeolite phase (PNZ) content such that O<PNZ30%, and an Si/Al atomic ratio of between 1.0 and 2.0. The invention also concerns a zeolite adsorbent material having an Si/Al ratio of between 1.0 and 2.0, a mesoporous volume of between 0.07 cm.sup.3.Math.g.sup.1 and 0.18 cm.sup.3.Math.g.sup.1, a (Vmicro-Vmeso)/Vmicro ratio of between 3 and 1.0, non-inclusive, and a non-zeolite phase (PNZ) content such that 0<PNZ30%.

Claims

1. A process for separation of at least one gas mixture, wherein the process comprises feeding the at least one gas mixture to at least one zeolite adsorbent material, wherein the at least one zeolite adsorbent material comprises at least one A zeolite, and wherein the at least one zeolite adsorbent material has physical properties that are measured on the at least one zeolite adsorbent material that has been at least 90% exchanged with calcium, and wherein the physical properties comprise: an external surface area, measured by nitrogen adsorption and expressed in m.sup.2 per gram of adsorbent greater than 20 m.sup.2.Math.g.sup.1; a non-zeolite phase (PNZ) content such that 0<PNZ30% as measured by XRD (X-ray diffraction), by weight relative to the total weight of the zeolite adsorbent material; a mesopore volume of between 0.07 cm.sup.3.Math.g.sup.1 and 0.18 cm.sup.3.Math.g.sup.1, limits included; and an Si/Al atomic ratio of between 1.0 and 2.0.

2. The process according to claim 1, wherein the at least one zeolite adsorbent material has a (VmicroVmeso)/Vmicro ratio of between 0.5 and 1.0, limits not included, where Vmicro is the micropore volume measured by the Dubinin-Raduskevitch method and Vmeso is the mesopore volume determined by the Barrett-Joyner-Halenda (BJH) method, wherein all of the measurements are carried out on the zeolite adsorbent material that has been at least 90% exchanged with calcium.

3. The process according the claim 1, wherein the at least one zeolite adsorbent material has a micropore volume (Dubinin-Raduskevitch volume), expressed in cm.sup.3 per gram of zeolite adsorbent material, of between 0.160 cm.sup.3.Math.g.sup.1 and 0.280 cm.sup.3.Math.g.sup.1 as measured on the at least one zeolite adsorbent material that has been at least 90% exchanged with calcium.

4. The process according to claim 1, wherein the at least one A zeolite has an Si/Al ratio equal to 1.00+/0.05, wherein the Si/Al ratio is measured by solid silicon 29 Nuclear Magnetic Resonance (NMR).

5. The process according to claim 1, wherein the at least one zeolite adsorbent material comprises at least one cation selected from the group consisting of the ions of groups IA, IIA, IIIA, IB, IIB, and IIIB of the periodic table, the trivalent ions of the lanthanide series of the periodic table, the trivalent ions of the rare earth series of the periodic table, the zinc(II) ion, the silver(I) ion, the cupric (II) ion, the chromium(III) ion, the ferric (III) ion, the ammonium ion, the hydronium ion, the calcium ion, lithium ion, sodium ion, potassium ion, barium ion, cesium ion, strontium ion, zinc ion, and mixtures thereof.

6. The process according to claim 1, wherein the gas mixture comprises cracked gases and water and the water is separated from the cracked gases.

7. The process according to claim 6, wherein the at least one zeolite adsorbent material comprises at least one 3A zeolite, wherein the at least one 3A zeolite is mesoporous.

8. The process according to claim 1, wherein the gas mixture comprises water and at least one refrigerant fluid selected from the group consisting of HFCs and HFOs, and the water is separated from the at least one refrigerant fluid.

9. The process according to claim 8, wherein the zeolite adsorbent material comprises at least one mesoporous A zeolite, wherein the at least one mesoporous A zeolite is selected from the group consisting of 3A zeolites, 4A zeolites, 5A zeolites, and mixtures thereof.

10. The process according to claim 1, wherein the gas mixture comprises water and ethanol, and wherein the water is separated from the ethanol.

11. The process according to claim 10, wherein the at least one zeolite adsorbent material comprises at least one mesoporous 3A zeolite.

12. The process according to claim 1, wherein the gas mixture comprises air and water, and the water is separated from the air.

13. The process according to claim 12, wherein the zeolite adsorbent material comprises at least one mesoporous A zeolite, wherein the mesoporous A zeolite is selected from the group consisting of 3A zeolites, 4A zeolites, 5A zeolites, and mixtures thereof.

14. The process according to claim 1, wherein the gas mixture comprises olefins, and oxygen-bearing impurities, and wherein the oxygen-bearing impurities are separated from the olefins.

15. The process according to claim 14, wherein the zeolite adsorbent material comprises at least one mesoporous A zeolite, wherein the at least one mesoporous A zeolite is selected from the group consisting of 3A zeolites, 4A zeolites, 5A zeolites, and mixtures thereof.

16. The process according to claim 1, wherein the gas mixture comprises natural gas and at least one impurity, wherein the at least one impurity is selected from the group consisting of carbon dioxide, hydrogen sulfide, light mercaptans, water, and mixtures thereof, and wherein the at least one impurity is separated from the natural gas.

17. The process according to claim 16, wherein the zeolite adsorbent material comprises at least one mesoporous A zeolite, wherein the at least one mesoporous A zeolite is selected from the group consisting of 3A zeolites, 4A zeolites, 5A zeolites, and mixtures thereof.

18. The process according to claim 1 wherein the gas mixture comprises paraffins and wherein the paraffins are separated.

19. The process according to claim 18, wherein the zeolite adsorbent material comprises at least one mesoporous 5A zeolite.

20. The process according to claim 1, wherein the gas mixture comprises syngases, water, impurities, and hydrogen, and wherein the hydrogen is separated from the syngases, water, and impurities.

21. The process according to claim 20, wherein the zeolite adsorbent material comprises at least one mesoporous A zeolite, wherein the at least one mesoporous A zeolite is selected from the group consisting of 3A zeolites, 4A zeolites, 5A zeolites, and mixtures thereof.

22. A zeolite adsorbent material, wherein the zeolite adsorbent material has physical properties that are measured on the zeolite adsorbent material that has been at least 90% exchanged with calcium, and wherein the physical properties comprise: an Si/Al ratio such that 1.0Si/Al<2.0; a mesopore volume of between 0.07 cm.sup.3.Math.g.sup.1 and 0.18 cm.sup.3.Math.g.sup.1, limits included; a (VmicroVmeso)/Vmicro ratio of between 0.3 and 1.0, limits not included, wherein the Vmicro is measured by the Dubinin-Raduskevitch method and the Vmeso is measured by the BJH method, and; a non-zeolite phase (PNZ) content such that 0<PNZ30%, by weight relative to the total weight of the zeolite adsorbent material, wherein the PNZ is measured by X-Ray diffraction.

23. The zeolite adsorbent material according to claim 22, wherein the Vmicro (Dubinin-Raduskevitch volume), expressed in cm.sup.3 per gram of zeolite adsorbent material is between 0.160 cm.sup.3.Math.g.sup.1 and 0.280 cm.sup.3.Math.g.sup.1, wherein the micropore volume is measured on the zeolite adsorbent material that has been at least 90% exchanged with calcium.

24. The zeolite adsorbent material according to claim 22, wherein the physical properties further comprise a total volume of macropores and mesopores, measured by mercury intrusion on the zeolite adsorbent material that has been at least 90% exchanged with calcium, wherein the total volume of macropores and mesopores is between 0.15 cm.sup.3.Math.g.sup.1 and 0.50 cm.sup.3.Math.g.sup.1.

25. The zeolite adsorbent material according to claim 22, wherein the physical properties further comprise an external surface area, measured by nitrogen adsorption on the zeolite adsorbent material at least 90% exchanged with calcium, and wherein the external surface area expressed in m.sup.2 per gram of adsorbent is greater than 20 m.sup.2.Math.g.sup.1.

26. The zeolite adsorbent material according to claim 22, wherein the physical properties further comprise a volumetric micropore volume measured on the zeolite adsorbent material which has been at least 90% exchanged with calcium and expressed in cm.sup.3.cm.sup.3 of zeolite adsorbent material at least 90% exchanged with calcium, of greater than 0.01 cm.sup.3.cm.sup.3.

27. The zeolite adsorbent material according to claim 22, wherein the physical properties further comprise a total macropore and mesopore volume, and a macropore volume fraction, wherein the total macropore and mesopore volume and the macropore volume fraction are measured by mercury intrusion on the zeolite adsorbent material at least 90% exchanged with calcium, wherein the total macropore and mesopore volume is between 0.15 cm.sup.3.Math.g.sup.1 and 0.5 cm.sup.3.Math.g.sup.1, and the macropore volume fraction is between 0.2 and 1.

28. The process according to claim 1, wherein the gas mixture comprises water, 1,1,1,2-tetrafluoroethane and 2,3,3,3-tetrafluoropropene and the water is separated from the 1,1,1,2-tetrafluoroethane and 2,3,3,3-tetrafluoropropene.

29. The process according to claim 28, wherein the zeolite adsorbent material comprises at least one mesoporous A zeolite, wherein the at least one mesoporous A zeolite is selected from the group consisting of 3A zeolites, 4A zeolites, 5A zeolites, and mixtures thereof.

30. The process according to claim 1, wherein the gas mixture comprises at least one industrial gas and water, and the water is separated from the at least one industrial gas.

31. The process according to claim 30, wherein the zeolite adsorbent material comprises at least one mesoporous A zeolite, wherein the mesoporous A zeolite is selected from the group consisting of 3A zeolites, 4A zeolites, 5A zeolites, and mixtures thereof.

32. The process according to claim 1, wherein the gas mixture comprises air and the process comprises air separation.

33. The process according to claim 32, wherein the zeolite adsorbent material comprises at least one mesoporous A zeolite, wherein the mesoporous A zeolite is selected from the group consisting of 3A zeolites, 4A zeolites, 5A zeolites, and mixtures thereof.

Description

EXAMPLE 1

Preparation of a Zeolite Adsorbent Material According to the Invention

Step 1

Synthesis of Mesoporous A Zeolite with Addition of Nucleating Gel and Growth Gel

a) Preparation of the Growth Gel

[0136] A growth gel is prepared in a 1.5 liter glass reactor stirred with a 3-blade propeller at 600 rpm equipped with a heating jacket and a temperature probe, by mixing an aluminate solution containing 151 g of sodium hydroxide (NaOH), 112.4 g of alumina trihydrate (Al.sub.2O.sub.3.3H.sub.2O, containing 65.2% by weight of Al.sub.2O.sub.3) and 212 g of water at 35 C. over 5 minutes, with a stirring speed of 600 rpm, with a silicate solution containing 321.4 g of sodium silicate and 325 g of water at 35 C.

[0137] The stoichiometry of the growth gel is as follows: 3.13 Na.sub.2O/Al.sub.2O.sub.3/1.92 SiO.sub.2/68 H.sub.2O. Homogenization of the growth gel is performed with stirring at 600 rpm for 15 minutes at 35 C.

b) Addition of the Nucleating Gel

[0138] 11.2 g of nucleating gel (i.e. 1% by weight) of composition 2.05 Na.sub.2O/Al.sub.2O.sub.3/1.92 SiO.sub.2/87 H.sub.2O prepared in the same manner as the growth gel, and which has matured for 2 hours at 25 C., is added to the growth gel, at 35 C. with stirring at 300 rpm. After 5 minutes of homogenization at 300 rpm, the stirring speed is reduced to 190 rpm and stirring is continued for 30 minutes.

c) Introduction of the Structuring Agent into the Reaction Medium

[0139] 35.7 g of a solution of [3-(trimethoxysilyl)propyl]octadecyldimethylammonium chloride (TPOAC) at 60% in methanol (MeOH) are introduced into the reaction medium with a stirring speed of 600 rpm (TPOAC/Al.sub.2O.sub.3 mole ratio=0.04). A maturation step is performed at 35 C. for 10 minutes at 300 rpm before starting the crystallization.

d) Crystallization

[0140] The stirring speed is lowered to 190 rpm and the set point of the reactor jacket is fixed at 105 C. so that the reaction medium increases in temperature to 97 C. over the course of 40 minutes. After 3 hours at a stationary temperature phase of 97 C., the reaction medium is cooled by circulating cold water through the jacket to stop the crystallization.

e) Filtration/Washing

[0141] The solids are recovered on a sinter and then washed with deionized water to neutral pH.

f) Drying

[0142] Drying is performed in an oven at 90 C. for 8 hours to obtain a solid with a loss on ignition of 20%.

Step 2

Calcium Exchange to Obtain a Mesoporous CaA Zeolite Powder

a) Calcium Exchanges

[0143] A calcium exchange is carried out in order to obtain a micropore diameter of approximately 0.5 nm: the exchange conditions are the following: 50 g of dried powder are brought into contact with 500 cm.sup.3 of 0.5 M CaCl.sub.2 solution at 70 C. for 2 hours, and then the mixture is filtered and washing is carried out with 280 cm.sup.3 of water. The operation is repeated 3 times (triple exchange). A degree of calcium exchange of 92% is obtained.

b) Drying

[0144] The drying is carried out in an oven at 90 C. for 8 hours in order to obtain a solid with a loss on ignition of 20%.

c) Calcination

[0145] The calcination of the dried product, required in order to free both the microporosity (water) and the mesoporosity by removing the structuring agent, is carried out by degassing under vacuum with a gradual increase in steps of 50 C. up to 400 C. for a period of between 9 hours and 16 hours, under vacuum (P<6.710.sup.4 Pa).

[0146] The micropore volume and the external surface area, measured according to the t-plot method from the nitrogen adsorption isotherm at 77 K after degassing under vacuum at 400 C. for 10 hours, are respectively 0.208 cm.sup.3.Math.g.sup.1 and 92 m.sup.2.Math.g.sup.1. The number-average diameter of the crystals is 0.8 m. The mesopore diameters calculated from the nitrogen adsorption isotherm by the DFT method are between 5 nm and 10 nm. The XR diffractogram corresponds to a pure LTA structure, no other zeolite phases are detected. The Si/Al mole ratio of the mesoporous CaA zeolite determined by X-ray fluorescence is equal to 1.02.

Step 3

Preparation of Mesoporous CaA Zeolite Agglomerates

[0147] In the subsequent text, the weights given are expressed in anhydrous equivalent.

[0148] A homogeneous mixture consisting of 1700 g of mesoporous CaA zeolite crystals obtained in step 2, of 300 g of Zeoclay attapulgite, sold by CECA, and also of the amount of water such that the loss on ignition of the paste before forming is 35%, is prepared. The paste thus prepared is used on a granulating plate in order to prepare balls of agglomerated zeolite adsorbent material. Selection by sieving of the balls obtained is carried out so as to collect balls having a diameter of between 0.3 and 0.8 mm and a volume-average diameter equal to 0.55 mm.

[0149] The balls are dried overnight in a ventilated oven at 80 C. They are then calcined for 2 h at 550 C. under nitrogen flushing, then 2 h at 550 C. under flushing with decarbonated dry air.

Step 4

Characterizations

[0150] The external surface area of the mesoporous CaA balls is equal to 92 m.sup.2.Math.g.sup.1 of adsorbent, the micropore volume is 0.202 cm.sup.3.Math.g.sup.1 of adsorbent. The volumetric micropore volume is 0.131 cm.sup.3 per cm.sup.3 of zeolite adsorbent material. The mesopore volume is equal to 0.140 cm.sup.3.Math.g.sup.1 of sodium-exchanged adsorbent. The total macropore and mesopore volume, measured by mercury intrusion, is 0.41 cm.sup.3.Math.g.sup.1 of adsorbent.

[0151] The Si/Al atomic ratio of the adsorbent is 1.25. The Si/Al ratio of the zeolite present in the adsorbent zeolite material, which is equal to 1.01, is determined by solid silicon 29 NMR.

[0152] The content of non-zeolite phase (PNZ), measured by XRD and expressed by weight relative to the total weight of the adsorbent, is 15.0%.

EXAMPLE 2

Comparative Zeolite Adsorbent Material

[0153] Siliporite NK20 sieve from CECA is a material based on CaA zeolite agglomerated with attapulgite. The volumetric mean diameter of the balls is equal to 0.55 mm. The content of calcium oxide CaO, measured by ICP-AES, is 15.7% by weight relative to the total weight of sieve or a degree of Ca exchange related back to the powder of 92%.

[0154] The external surface area is equal to 39 m.sup.2.Math.g.sup.1 of adsorbent, the micropore volume is 0.238 cm.sup.3.Math.g.sup.1 of adsorbent. The volumetric micropore volume is 0.167 cm.sup.3 per cm.sup.3 of zeolite adsorbent material. The mesopore volume is equal to 0.07 cm.sup.3.Math.g.sup.1 of adsorbent. The total macropore and mesopore volume, measured by mercury intrusion, is 0.30 cm.sup.3.Math.g.sup.1 of sodium-exchanged adsorbent.

[0155] The Si/Al atomic ratio of the adsorbent is 1.23. The content of non-zeolite phase (PNZ), measured by XRD and expressed by weight relative to the total weight of the adsorbent, is 15.5%.

EXAMPLE 3

N.SUB.2./O.SUB.2 .Separation Tests on a Fixed Bed of Adsorbant with Pressure Swing Adsorption

[0156] An N.sub.2/O.sub.2 separation test is carried out by adsorption in a single column according to a principle presented in E. Alpay et al. (ibid.).

[0157] FIG. 1 describes the assembly produced. A column (1) of internal diameter equal to 27.5 mm and of internal height equal to 600 mm, filled with zeolite adsorbent material (2), is fed with dry air (3) intermittently by means of a valve (4). The time for feeding the column (1) with the stream (3) is called adsorption time. When the column (1) is not fed with dry air, the stream (3) is discharged into the atmosphere by the valve (5). The zeolite adsorbent material preferentially absorbs nitrogen, so that an oxygen-enriched air leaves the column via the non-return valve (6), to a buffering tank (7). A regulating valve (8) continuously delivers the gas at outlet (9) at a constant flow rate fixed at 1 NL.min.sup.1. When the column (1) is not fed, that is to say when the valve (4) is closed and the valve (5) is open, the column (1) is depressurized by the valve (10) to the atmosphere (11), for a period called the desorption time. The adsorption and desorption phases follow on from one another. The durations of these phases are fixed from one cycle to the other and they are adjustable. Table 1 indicates the respective state of the valves as a function of the adsorption and desorption phases.

TABLE-US-00001 TABLE 1 Adsorption phase Desorption phase Valve (4) open Valve (4) closed Valve (5) closed Valve (5) open Valve (10) closed Valve (10) open

[0158] The tests are carried out successively with the zeolite adsorbent materials of example 1 (according to the invention) and of example 2 (comparative). The column is loaded at constant volume, with respectively 241.2 g and 259.2 g of adsorbent materials.

[0159] The pressure at the inlet is fixed at 280 kPa relative. The outlet flow rate is fixed at 1 NL.min.sup.1. The adsorption time is fixed at 0.25 s. The desorption time is variable between 0.25 s and 1.50 s. The oxygen concentration at outlet (9) is measured by means of a Servomex 570A oxygen analyzer.

[0160] FIG. 2 shows the oxygen content of the stream produced at outlet (9) as a function of the desorption time fixed for the materials of example 1 and example 2. Despite a lower weight loaded into the column, the material of example 1 (according to the invention) proves to be much more efficient than the solid of example 2 (comparative).