EP4065253A1

EP4065253A1 - Separation of gases from air

Info

Publication number: EP4065253A1
Application number: EP20821052.6A
Authority: EP
Inventors: Guillaume ORTIZ; Quitterie Persillon
Original assignee: Arkema France SA
Current assignee: Arkema France SA
Priority date: 2019-11-27
Filing date: 2020-11-23
Publication date: 2022-10-05
Also published as: ZA202204148B; TWI801779B; CN114728230B; CA3153854C; FR3103393A1; FR3103393B1; TW202128551A; KR20220082077A; US20220387923A1; CA3153854A1; CN114728230A; JP2023503620A; WO2021105598A1; AU2020394572A1; AU2024201578A1; IL292022A

Abstract

The present invention relates to the use of an adsorbent zeolitic material made from crystals of faujasite zeolite (FAU), the molar ratio Si/Al of which is between 1.00 and 1.20, and which have such a non-zeolitic phase content (PNZ) that 0 < PNZ ≤ 25%, for non-cryogenically separating industrial gases with (V)PSA, in particular gases from air. The invention also relates to respiratory aid apparatuses comprising at least the adsorbent zeolitic material.

Description

SEPARATION OF GAS FROM AIR

The invention relates to the separation of industrial gases in (V) PSA, in particular the separation of nitrogen and oxygen contained in the air, a very suitable application being the preparation of medical oxygen , other possible applications being VPSA applications for the preparation of industrial oxygen.

More specifically, the present invention relates to the use of specific adsorbent materials for the separation of gases from air and industrial gases, and more particularly for the separation of nitrogen by adsorption in gas streams such as as air, as well as the preparation _{of high purity oxygen (0 2} ) by adsorption of nitrogen (N ₂ ), and more particularly for the preparation of oxygen for medical use from air.

[0003] The separation of nitrogen from gas mixtures is the basis of several non-cryogenic industrial processes, including the production of oxygen from air by the PSA process ("Pressure Swing Adsorption", in English, either "Pressure swing adsorption") or VPSA ("Vacuum and Pressure Swing Adsorption", in English, or "Pressure swing adsorption under vacuum"), the PSA process being one of the most important.

In this application, the air is compressed and sent to an adsorbent column having a marked preference for the nitrogen molecule. In this way, during the adsorption cycle, oxygen is produced with a purity of about 94-95% and argon. After a certain period of time, the column is depressurized and then maintained at low pressure, during which time the nitrogen is desorbed. Recompression is then ensured by means of part of the oxygen produced and / or by air, then the cycle continues. The advantage of this process compared to the cryogenic processes commonly used lies in the greater simplicity of the installations, greater ease of maintenance, and consequently more efficient uses and more economical implementations, in particular for small to medium-sized installations, that is, producing a few tens of tonnes or less of purified gas per day.

[0005] The quality of the adsorbent used, however, remains the key to an efficient and competitive process. The performance of the adsorbent is linked to several factors, including the nitrogen adsorption capacity and the selectivity between nitrogen and oxygen which will be decisive in sizing the column sizes and optimizing the production yield (ratio between oxygen produced and oxygen entered), the kinetics adsorption which will optimize cycle times and improve plant productivity.

[0006] Patent US6596256 B1 discloses a process for preparing sodium LSX and sodium MSX zeolites, without adding potassium. The zeolites thus prepared are then subjected to cation exchange with lithium ions, calcium ions, rare earth cations, or mixtures of these cations, before being used, for example for the nitrogen / oxygen separation, in the case of LSX zeolite exchanged with lithium.

[0007] Patent US5464467 A describes a process for preparing nitrogen from a gas mixture comprising passing said gas mixture through at least one adsorption zone containing an X zeolite comprising from 50% to approximately 95% lithium ions. Such lithium zeolites exhibit quite advantageous oxygen production capacities, and in particular better than the absorption capacities obtained with the zeolites of the prior art, or comprising other cations.

Also known are zeolite adsorbents based on zeolites of faujasite type (FAU), and in particular adsorbents based on zeolites with a low silicon / aluminum molar ratio exchanged with lithium (LiLSX) which are for example described in the international application WO2018100318. These adsorbents have been shown not only to be very suitable but also very effective for oxygen / nitrogen separation, and in particular for the preparation of medical oxygen from air.

[0009] The prior art therefore teaches those skilled in the art that the production of oxygen from gas mixtures (for example from a nitrogen / oxygen mixture or even from air) is optimized by using zeolitic adsorbents based on X zeolites, better still based on LSX zeolites, and which contain lithium ions. [0010] In fact, zeolitic adsorbents exchanged with lithium are marketed today for the nitrogen / oxygen separation, which are considered to be the most efficient. However, adsorbents exchanged with lithium suffer from a relatively high manufacturing cost due in particular to the cost inherent in that of metallic lithium, which is a metal whose natural resources are constantly diminishing.

In order to overcome these drawbacks and in particular to reduce the use of zeolitic adsorbents comprising lithium, US Pat. No. 6,027,548 A proposes to use columns of multilayer adsorbents superimposing adsorbents of the NaX and LiX type. Despite the relatively low performance of NaX type adsorbents compared to those of LiX type adsorbents, the multilayer adsorbents described in this document are of moderate cost and are presented as allowing an interesting cost / performance ratio. Indeed, it is well known that NaX type adsorbents can sometimes be used because of their low manufacturing / marketing cost compared to adsorbents exchanged with lithium. NaX-type adsorbents are, however, less efficient in terms of nitrogen adsorption capacity and nitrogen / oxygen selectivity. [0013] There therefore remains a need for products which remain inexpensive and have good performance in terms of nitrogen adsorption capacity and nitrogen / oxygen selectivity. Thus a first objective of the present is to provide inexpensive zeolitic adsorbents and having good performance or even very good performance in terms of gas separation, in particular in terms of nitrogen / oxygen separation, and more particularly in terms of production. oxygen and in particular medical oxygen.

As a very particularly targeted objective, there is proposed a zeolitic adsorbent at low cost and which is very selective in the nitrogen / oxygen separation, and in particular which has the capacity to retain nitrogen without the oxygen being retained, more particularly a zeolitic adsorbent which selectively adsorbs nitrogen, while not adsorbing oxygen or only very weakly.

One of the objectives of the present invention consists in particular of improving the zeolitic adsorbents (also called "sieves") existing sodium grades for the separation of nitrogen and oxygen, by providing solids which do not retain or which very little oxygen and very preferably nitrogen. Still other objects will become apparent from the description of the invention which follows.

The Applicant has now discovered that the aforementioned objectives can be achieved in whole, or at least in part, by virtue of the present invention which follows and which is described below.

It has now been discovered that it is possible to prepare zeolite adsorbent materials, from FAU-type zeolite crystals, for the non-cryogenic separation of industrial gases in (V) PSA, in particular for the separation of nitrogen and oxygen (N _2/0 _2), especially for the preparation of medical oxygen from air and for the industrial preparation of oxygen (V) PSA.

[0018] Thus, and according to a first aspect, the present invention relates to the use of a zeolitic adsorbent material:

- based on crystals of faujasite zeolite (s) (FAU), the Si / Al molar ratio of which is between 1.00 and 1.20, better still between 1.00 and 1.15 and preferably 1.00 and 1. , 12, terminals included,

- and with a non-zeolitic phase (PNZ) content such that 0 <PNZ <25%, preferably 0 <PNZ <20%, more preferably 0 <PNZ <15%, advantageously 0 <PNZ <10%, even more advantageously 0 <PNZ <8%, by weight relative to the total weight of the zeolitic adsorbent material, for the non-cryogenic separation of industrial gases in (V) PSA, in particular for the separation of nitrogen and oxygen (N _2/0 _2), and typically for the preparation of medical oxygen from air and for the industrial preparation of oxygen (V) PSA. [0019] According to a preferred aspect, the sodium content of the zeolitic adsorbent which can be used in the context of the present invention is generally greater than 95%, preferably greater than 97%, more preferably greater than 98%, more preferably still. greater than 99%, limits included, these sodium contents being expressed as percentages of exchangeable sites. With a sodium content greater than 95%, the zeolitic adsorbent for use in the context of the present invention is hereinafter referred to as “sodium grade zeolitic adsorbent”, or also “sodium grade sieve”. For the purposes of the present invention, it should be understood that the zeolites which can be used to form the aforementioned zeolitic adsorbents are synthesized from sodium solutions and advantageously do not undergo any ion exchange or else an ion exchange, so that the Exchangeable sites of the zeolitic adsorbent after exchange are occupied to more than 95%, preferably more than 97%, more preferably more than 98%, more preferably more than 99%, limits included, by sodium ions. [0021] Thus, and according to a very particularly preferred embodiment of the present invention, the zeolitic adsorbents which can be used for the non-cryogenic separation of industrial gases and in particular gases from the air, are sodium-grade zeolitic adsorbents whose exchangeable sites are more than 95% occupied by sodium ions and whose content of cations other than sodium is less than 5% expressed as oxides, and preferably less than 4%, better still less than 2%, the cations other than sodium being chosen from lithium, potassium, barium, calcium, strontium, cesium, and transition metals such as silver, for example and preferably chosen from lithium, potassium, calcium and barium.

In addition, the zeolite crystals (s) which form the zeolite adsorbents that can be used in the context of the present invention are faujasite-type zeolite crystals (called FAU-type zeolites) whose silicon / molar ratio aluminum (Si / Al molar ratio) is low to moderate. In other words, the zeolite crystals (s) which form the zeolite adsorbent which can be used in the context of the present invention are chosen from zeolite crystals of the FAU LSX type, that is to say with an Si / ratio. Al equal to 1.00, and zeolites of FAU MSX type, that is to say with an Si / Al ratio corresponding to the equation 1.00 <Si / Al <1. 20. It has been discovered, quite surprisingly, that for similar nitrogen adsorption capacities, the oxygen adsorption capacities are even lower than the Si / Al ratio of the zeolites of the adsorbents. zeolite sodium grades which can be used in the context of the invention is low. In other words, the lower the Si / Al ratio of the zeolites of the sodium grade zeolitic adsorbents, the less oxygen is adsorbed, while nitrogen is adsorbed well.

Thus, and as indicated above, it is preferred among the zeolites which can be used for the preparation of the zeolitic adsorbents useful for the present invention, the FAU type zeolites, which are LSX or MSX zeolites, and in in particular, FAU type zeolites in which the Si / Al molar ratio is between 1.00 and 1.20, preferably between 1.00 and 1.15 and preferably 1.00 and 1.12, limits included.

According to one embodiment of the present invention, the zeolites of the FAU LSX type (Si / Al molar ratio = 1.00) are most particularly preferred for the preparation of zeolitic adsorbents which can be used for the nitrogen / oxygen separation. The possible different types of zeolites present in the zeolitic adsorbent material are determined by XRD. The total quantity of zeolite (s) is also measured by XRD and is expressed in% by weight relative to the total weight of the adsorbent material.

In addition, and as indicated above, the zeolitic adsorbent material has a certain amount of non-zeolitic phase, called PNZ. In the present invention, the term “non-zeolitic phase” (or “PNZ”) denotes any phase present in the zeolitic adsorbent material according to the invention, other than the zeolite (s) present in said zeolitic adsorbent material. , called “zeolitic phase” or “PZ”. The amount of non-zeolitic phase is expressed by the complement to 100% of the zeolitic phase of the adsorbent, that is to say according to the following equation:

% PNZ = 100 -% PZ, where% PNZ represents the percentage by weight of PNZ and% PZ the percentage by weight of zeolitic phase, relative to the total weight of the zeolitic adsorbent material.

Thus and as indicated above, the PNZ of the zeolitic adsorbent material useful in the context of the present invention is such that 0 <PNZ <25%, preferably 0 <PNZ <20%, more preferably 0 <PNZ <15 %, advantageously 0 <PNZ <10%, even more advantageously 0 <PNZ <8%, by weight relative to the total weight of the zeolitic adsorbent material.

The zeolitic adsorbent material which can be used in the context of the present invention, whether in the form of beads, extrudates or the like, generally has a diameter average volume, or an average length (greater dimension when it is not spherical), less than or equal to 7 mm, preferably between 0.05 mm and 5 mm, more preferably between 0.2 mm and 3 mm. For the purposes of the present invention, a zeolitic adsorbent material in the form of beads is preferred.

The zeolitic adsorbent materials useful in the context of the present invention also exhibit mechanical properties which are very particularly suitable for the applications for which they are intended, that is to say:

- or a bed crushing strength (REL) measured according to standard ASTM 7084-04 greater than 1.5 MPa, preferably greater than 2.0 MPa, preferably greater than 2.5 MPa, for a material of average volume diameter (d ₅ o) or a length (largest dimension when the material is not spherical), less than 1 mm, terminals included,

- or a grain crushing resistance, measured according to standards ASTM D 4179 (2011) and ASTM D 6175 (2013), between 0.5 daN and 30 daN, preferably between 1 daN and 20 daN, for a material with an average volume diameter (d ₅ o) or a length (largest dimension when the material is not spherical) greater than or equal to 1 mm, limits included.

More specifically and according to a preferred embodiment of the invention, the zeolitic adsorbent material is in the form of beads, the average volume diameter of which is between 0.05 mm and 5 mm, limits included. More preferably, and more specifically for applications for preparing oxygen for medical use, this mean volume diameter is between 0.05 mm and 1.0 mm, more preferably between 0.15 mm and 0.65 mm, and most preferably between 0.25 mm and 0.55 mm. For applications such as the separation of industrial gases, this mean volume diameter can be more specifically and more generally between 1.0 mm and 5.0 mm.

Another preferred characteristic of the zeolitic adsorbent material of the invention is its bulk density which is generally between 0.55 kg nr ³ and 0.80 kg nr ³ , preferably between 0.58 kg nr ³ and 0 , 75 kg nr ³ , more preferably between 0.60 kg nr ³ and 0.70 kg nr ³ .

The invention also relates to a process for preparing the zeolitic adsorbent material which can be used in the context of the present invention, which comprises the following steps: a / agglomeration of FAU LSX and / or FAU MSX zeolite crystals, with a binder of agglomeration, then shaping, drying and calcination of the agglomerated crystals, b / optional zeolitization of at least part of the binder by the action of a basic alkaline solution, d optional replacement of the cations of the exchangeable sites of the product obtained in step a / or in step b / with sodium cations, then washing and drying the product thus treated, and d / activating the zeolitic adsorbent material obtained.

If the zeolite step b / is carried out, it may be advantageous to add a source of silica during step a /, in order in particular to promote conversion of the binder into an FAU-type zeolite.

The type zeolite used in step a / of the process described above is, as indicated above, an FAU type zeolite with an Si / Al molar ratio of between 1.00 and 1.20, limits included, as indicated previously.

These zeolite crystals can be prepared by any means known to those skilled in the art and can for example be obtained according to a process similar to that described in documents FR2925478 or US6596256.

In the preparation process above, all the amounts indicated are expressed in calcined equivalents, that is to say by weight or percentage by mass, subtracting the loss on ignition (PAF) measured on each ingredient introduced. It is also possible to use in this step a / crystals of zeolite of the FAU type at least partially exchanged with rare earths, as described for example in US5464467.

The quantity by weight of FAU-type zeolite crystals is generally between 75% and 95% by weight, relative to the total weight of said product obtained at the end of step a / and the quantity of zeolitisable clay as for it is generally between 5% and 25% by weight, relative to the total weight of said product obtained at the end of step a /.

When a source of silica is added, an amount of between 0.1% and 10% by weight is preferably added, more preferably between 0.2% and 6% by weight, relative to the total weight of said product obtained at the end of step a /. The source of silica which can be used is of any type known per se, for example solid silica, colloidal silica, sodium silicate, and other sources well known to those skilled in the art. The shaping in step a / is carried out according to techniques well known to those skilled in the art. Likewise, the drying and calcination are carried out according to the usual descriptions also well known to those skilled in the art. Thus, the drying is typically carried out at a temperature between 50 ° C and 200 ° C. The calcination can be carried out according to any method of calcination known to those skilled in the art and by example, and in a nonlimiting manner, the calcination can be carried out under oxidizing and / or inert gas sweeping, in particular with gases such as oxygen, nitrogen, air, dry and / or decarbonated air, air oxygen-depleted, optionally dry and / or decarbonated, at one or more temperatures above 200 ° C, typically between 250 ° C and 700 ° C, preferably between 300G and 650 ° C, for a few hours, for example between 1 and 6 hours.

The agglomeration binder used in step a / can be chosen from conventional binders known to those skilled in the art and preferably chosen from clays and mixtures of clays, silicas, aluminas, colloidal silicas, alumina gels, and the like, and mixtures thereof.

The clays are preferably chosen from: kaolins, kaolinites, nacrites, dickites, halloysites, attapulgites, sepiolites, montmorillonites, bentonites, illites and metakaolins, as well as mixtures of two or more of them in all proportions. Preference is given to fibrous clays of the sepiolite or attapulgite type, the clay or clays being able, in general, to be formulated in the form of dry-ground and selected powders, or better still of gel (ie delaminated clays ) and dispersed, and optionally ground, such as the commercial Min-U-Gel ^® , Pansil ^® , Pangel ^® , Cimsil ^® , Attagel ^® , Actigel ^® , etc. clays, which may or may not have undergone one or more chemical treatments. Such gels are for example described in EP170299 or US6743745.

In another preferred embodiment, the agglomeration binder used in step a / preferably contains at least 80% by weight of clay (s) zeolite (s) (called "zeolite part") by relative to the total weight of the agglomeration binder.

The term "zeolitisable clay (s)" means a clay or a mixture of clays capable of being transformed into zeolitic material by the action of a basic alkaline solution, according to techniques now well known to those skilled in the art. The zeolitisable clays which can be used in the context of the present invention typically belong to the family of kaolinites, halloysites, nacrites, dickites, kaolins and / or metakaolins, clays to which a source can also be added. silica, as described above.

It is also possible to incorporate, in addition to the zeolitisable clay (s), one or more other types of non-zeolitisable clays, such as for example and without limitation clays chosen from among attapulgites, sepiolites, bentonites, montmorillonites, and others. This embodiment is however not preferred. It is also possible, during the agglomeration step al, to incorporate one or more organic additive (s), in particular with the aim of facilitating the shaping and / or of imparting properties. particular to the agglomerated material, such as mechanical strength, porous profiles, and others. These additives are well known to those skilled in the art and can be incorporated at contents of between 0 and 5% by weight relative to the total weight of said product obtained at the end of step a1.

Step b / of zeolitization allows the transformation into zeolitic material, of at least 50% and preferably at least 70%, more preferably at least 80% and more preferably at least 85%, by weight of the zeolitisable clay (s) contained in the binder. In a preferred embodiment, the zeolitic adsorbent which can be used in the context of the present invention comprises a binder which has not been zeolitized. Zeolithization can be carried out by immersing the agglomerate in a basic alkaline solution, generally aqueous, advantageously an aqueous solution of sodium hydroxide and / or potassium hydroxide, the concentration of which is preferably greater than 0.5 M. Said concentration is generally less than 5 M, preferably less than 4 M, advantageously less than 3 M.

Zeolithization is preferably carried out hot (temperature above ambient temperature), typically at temperatures of the order of 80 ° C to 100 ° C, in order to improve the kinetics of the process and thus reduce the times. immersion within 8 hours. However, it would not be departing from the scope of the invention to operate at lower temperatures and longer immersion times. It would also not be departing from the scope of the invention to add, during this zeolitization step, a source of liquid or solid silica in the basic alkaline solution, for example sodium silicate or dissolved silica.

According to this procedure and as indicated above, the zeolitization of at least 50% is easily obtained, and preferably at least 70%, more preferably at least 80% and more preferably at least. less 85%, by weight of the zeolitisable clay (s) contained in the binder. Washing is then carried out with water followed by drying.

The possible step c / of replacing the cations of the exchangeable sites of the product obtained in step b / with sodium cations is only desirable, or even necessary, when the sodium content of the zeolite is such that less 95% of the exchangeable sites are occupied by sodium ions. Such an exchange can then be carried out according to methods well known to those skilled in the art and such as, for example, those described in patent EP0893157. In the present application, the term “exchangeable sites” is understood to mean all of the exchangeable sites of the zeolite crystals, as well as the exchangeable sites formed during the zeolitization of the binder. In a preferred embodiment of the invention, the possible exchange with sodium is carried out so that the sodium content (expressed as a percentage of exchangeable sites) in the zeolitic adsorbent material of the invention is equal to or greater than 95% .

In addition to the possible exchange with sodium cations, it is also possible to carry out an exchange with one or more other cations of Groups IA, MA, NIA and INB (respectively columns 1, 2, 13 and 3) of the periodic classification of the elements, but also with one or more other trivalent ions of the lanthanide or rare earth series, the zinc ion (II), the cupric ion (II), the chromic ion (III), the ferric (III) ion, the ammonium ion and / or the hydronium ion, provided that the zeolitic adsorbent material of the invention has a rate of exchangeable sites occupied by sodium ions at least equal to or greater than 95%.

The activation (step d /), last step of the process for obtaining the zeolitic adsorbent material according to the invention, aims to fix the water content, as well as the loss on ignition of the adsorbent in optimal limits. The procedure is generally carried out by thermal activation which is preferably carried out between 300 ° C and 650 ° C for a certain time, typically from 1 to 6 hours, depending on the water content and the loss on ignition desired and depending on the intended use of the adsorbent. In one embodiment, the calcination of step a / and the activation of step d / can be carried out concomitantly, that is to say at the same time in the same heated chamber, for example a oven.

The zeolitic adsorbent material according to the present invention finds a very particularly advantageous use as a nitrogen adsorbent material for the separation of gases from air and excellent adsorbents of nitrogen and / or carbon monoxide. for the purification of hydrogen.

The zeolitic adsorbent material according to the present invention most often has a mass adsorption capacity of nitrogen (N ₂ ), measured under 4 bar (0.4 MPa) at 25 ° C greater than 23 Ncrrf g ^-1 more preferably greater than 24 Nom ³ g ^-1 , more preferably greater than 25 Nom ³ g ^-1 , very particularly preferably greater than 26 Nom ³ g ^-1 .

As already indicated above, it has been observed quite surprisingly that the zeolitic adsorbent material according to the present invention also most often has a mass adsorption capacity of oxygen (0 ₂ ), measured. at 4 bar (0.4 MPa) at 25 ° C less than 12 Ncrrf g ^-1 , more preferably less than 11 Nom ³ g ¹ , more preferably less than 10 Nom ³ g ¹ , very particularly preferably less than 9 Ncm ³ g ^-1 . In the present description, the term “nitrogen / oxygen selectivity” is understood to mean the ratio between the mass adsorption capacity of nitrogen (N ₂ ), measured under 4 bar (0.4 MPa) at 25 ° C. and the capacity of mass adsorption of oxygen (0 ₂ ), measured under 4 bar (0.4 MPa) at 25 ° C, otherwise dt the capacity N ₂ / capacity 0 ₂ ratio, the capacities being measured under 4 bar (0.4 MPa) at 25 ° C.

[0060] Adsorption processes using the zeolite adsorbent material according to the present invention are most often type of PSA, VSA or VPSA, and preferably of the PSA or VPSA for separating N _2/0 ₂ Industrial Gases and for separating N _2/0 ₂ in the production of medical oxygen equipment.

The zeolitic adsorbent material according to the present invention thus finds a very particularly advantageous application as an adsorption element in oxygen concentrators for respiratory assistance. According to a particularly advantageous aspect of the invention, the zeolitic adsorbent material according to the invention constitutes the active material of a consumable cartridge of zeolitic adsorbent, which can be inserted into a respiratory assistance oxygen concentrator, whether stationary, transportable, or mobile, preferably portable.

The zeolitic adsorbent consumable cartridge can be of any suitable shape to be easily inserted and replaced in oxygen concentrators for respiratory assistance. According to one embodiment, said cartridge can be prepared from the zeolitic adsorbent material according to the invention in the form of beads made cohesive in them thanks to at least one resin, preferably a polymer resin preferably chosen from homo- and / or. thermoplastic copolymers and polycondensates. Nonlimiting examples of such polymer resins are polyolefins, in particular low and / or high and / or ultra-high density polyethylene, polypropylene, ethylene copolymers, ethylene-vinyl acetate copolymers, polyacrylics, acrylonitrile homo- and or copolymers, polyacrylates, polymethacrylates, acrylate copolymers and / or methacrylate copolymers, polystyrenes and / or styrene copolymers, polyesters, p. ex. polyethylene terephthalate, polybutylene terephthalate, halogenated polymers and copolymers such as poly (vinylidene difluoride) (PVDF) polymers, poly (tetrafluoroethylene) (PTFE) polymers and or copolymers, polyamides, such as polyamide- 11 and polyamide-12, as well as other even and odd polyamides, aromatic polyamides, polyvinyl chlorides, polyurethanes, polyethersulfones, polyetherketones, polycarbonates, epoxy resins, phenolic resins, thermosetting resins and elastomeric resins, and the like, as well as mixtures of two or more of them in all proportions.

According to yet another aspect, the invention relates to an oxygen concentrator for respiratory assistance, transportable, mobile, preferably portable, comprising at least one zeolitic adsorbent material, or at least one fixed adsorption bed, or at least one composite material, or at least one cartridge, as they have just been described above.

As a variant, the zeolitic material which can be used in the context of the present invention can be used in the form of adsorbent layers (also called adsorbent beds), preferably with one or two, three, or more, other adsorbent layers. The other adsorbent (s) can be of any type well known to those skilled in the art and mention may be made, by way of non-limiting examples, of adsorbents comprising zeolites chosen from CaLSX, LiTrLSX, 5A, NaX, LiX, LiAgLSX, LiLSX, LiCaLSX.

According to a very particularly preferred aspect, the use according to the present invention uses an adsorbent as defined above in a bilayer with an adsorbent based on LiLSX, thus forming a NaLSX / LiLSX or NaMSX / LiLSX bilayer, preferably a bilayer or NaLSX / LiLSX, and more preferably a NaLSX / LiLSX bilayer in which the NaLSX / LiLSX ratio is between 5/95 and 95/5, and better still between 50/50 and 95/5, in weight.

It has been observed that the zeolitic adsorbent material based on NaLSX and / or NaMSX, as it has just been defined, has an oxygen adsorption capacity lower than that of the adsorbent materials available today. , in the use of nitrogen / oxygen separation, according to the present invention, while retaining a very good nitrogen adsorption capacity.

This low oxygen adsorption capacity, coupled with a good nitrogen adsorption capacity, makes the zeolitic adsorbent material based on NaLSX and / or NaMSX, quite competitive, compared to zeolitic adsorbents commonly used today for nitrogen / oxygen separation and which most often contain lithium in greater or lesser quantity. In fact, the zeolitic adsorbent material used in the invention does not contain lithium or else in very small quantities, so that its manufacturing cost makes it quite interesting for users.

According to yet another aspect, the invention relates to an oxygen concentrator for respiratory assistance, transportable, mobile, preferably portable, comprising at least one zeolitic adsorbent material, or at least one fixed adsorption bed, or at least a composite material, or at least one cartridge, such as have just been described above.

[0070] A hub especially suitable for the separation of nitrogen and oxygen (N _2/0 _2), and in particular for the preparation of medical oxygen from air and for the industrial preparation of oxygen by (V) PSA, comprises a NaLSX / LiLSX or NaMSX / LiLSX bilayer, preferably a bi-layer or NaLSX / LiLSX, and more preferably a NaLSX / LiLSX bilayer in which the NaLSX / LiLSX ratio is between 5/95 and 95/5, and more preferably between 50/50 and 95/5, by weight.

The physical properties of the zeolitic adsorbent material which can be used in the context of the present invention are evaluated by methods known to those skilled in the art, the main ones of which are recalled below.

The examples which follow serve to illustrate the invention which has just been described above, and are not intended to limit the scope of protection conferred by the appended claims.

Characterization techniques - Analysis methods

The physical properties of the zeolitic agglomerated material according to the invention are evaluated by methods known to those skilled in the art, the main ones of which are recalled below. The estimation of the number-average diameter of the zeolite crystals which are used for the preparation of the zeolitic agglomerated material of the invention is carried out by observation under a scanning electron microscope (SEM).

In order to estimate the size of the zeolite crystals on the samples, a set of photographs is taken 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 in the order of 3%.

The size retained for each crystal is that of the largest section of said crystal considered. Particles smaller than 0.5 µm which could possibly be present in the zeolitic agglomerated material are not taken into account in the count.

The resulting particle size distribution is equivalent to the average of the particle size distributions observed on each of the photographs. The width of the peak and the number-average diameter are calculated according to conventional methods known to those skilled in the art, by applying the statistical rules of Gaussian distribution. An elementary chemical analysis of a zeolitic agglomerated material according to the invention can be carried out according to various analytical techniques known to those skilled in the art. Among these techniques, mention may be made of the technique of chemical analysis by X-ray fluorescence as described in standard NF EN ISO 12677: 2011 on a wavelength dispersive spectrometer (WDXRF), for example Tiger S8 from the company Bruker.

X fluorescence is a non-destructive spectral technique using the photoluminescence of atoms in the X-ray field, to establish the elemental composition of a sample. The excitation of atoms generally by a beam of X-rays or by bombardment with electrons, generates specific radiations after return to the ground state of the atom.

Other analysis methods are for example illustrated by the methods by atomic absorption spectrometry (AAS) and atomic emission spectrometry with induced plasma at high frequency (ICP-AES) described in the NF EN ISO standards. 21587-3 or NF EN ISO 21079-3 on a device such as Perkin Elmer 4300DV.

The X-ray fluorescence spectrum has the advantage of depending very little on the chemical combination of the element, which offers a precise determination, both quantitative and qualitative. In a conventional manner, after calibration, for each oxide Si0 ₂ and Al ₂ O ₃ , as well as the various oxides (such as those originating from exchangeable cations, for example sodium), a measurement uncertainty of less than 0.4% by weight is obtained.

Thus, the elementary chemical analyzes described above make it possible both to verify the Si / Al ratio of the zeolite used within the zeolitic agglomerated material and the Si / Al ratio of the zeolitic agglomerated material. In the description of the present invention, the measurement uncertainty of the Si / Al ratio is ± 5%. The measurement of the Si / Al ratio of the zeolite present in the agglomerated material can also be measured by solid Nuclear Magnetic Resonance (NMR) spectroscopy of silicon.

The quality of the ion exchange is linked to the number of moles of the cation considered in the zeolitic agglomerated material after exchange. More precisely, the rate of exchange by a given cation is estimated by evaluating the ratio between the number of moles of said cation and the number of moles of all the exchangeable cations. The respective amounts of each of the cations are evaluated by chemical analysis of the corresponding cations. For example, the exchange rate by sodium ions is estimated by evaluating the ratio between the total number of Na ⁺ cation and the total number of exchangeable cations (for example Ca ²⁺ , K ⁺ , Li ⁺ , Ba ²⁺ , Cs ⁺ , Na ⁺ , etc.), the quantity of each of the cations being evaluated by chemical analysis of the corresponding oxides (Na ₂ 0, CaO, K ₂ 0, BaO, Li ₂ 0, Cs ₂ 0, etc.). This calculation method also accounts for any oxides present in the residual binder of the zeolitic agglomerated material.

The resistance to bed crushing of zeolitic adsorbent materials as described in the present invention is characterized according to standard ASTM 7084-04.

The apparent density of the zeolitic agglomerated material according to the present invention is measured as described in standard DIN 8948 / 7.6.

The purity of the zeolites in the zeolitic adsorbent materials of the invention is evaluated by X-ray diffraction analysis, known to those skilled in the art by the acronym DRX. This identification is carried out on a DRX device of the Bruker brand. This analysis makes it possible to identify the different zeolites present in the agglomerated material because each of the zeolites has a unique diffractogram defined by the positioning of the diffraction peaks and by their relative intensities.

The zeolitic adsorbent materials are ground and then spread and smoothed on a sample holder by simple mechanical compression. The conditions for acquiring the diffractogram produced on the D8 ADVANCE device from Bruker are as follows:

• Cu tube used at 40 kV - 30 mA;

• size of the Soller's slits = 2.5 ⁰ , with width cb the irradiation surface of 16 mm;

• rotating sample device: 10 rpm ¹ ;

• measuring range: 4 ° <2Q <70 °;

• pitch: 0.015 °;

• counting time per step: 0.8 seconds.

The interpretation of the diffractogram obtained is carried out with the EVA software with identification of the zeolites using the ICDD PDF-2 database, release 2011.

The amount of FAU zeolite fractions, by weight, is measured by X-ray fluorescence analysis or by XRD, the latter method can also be used to measure the amount of zeolite fractions other than FAU. The XRD analysis is generally carried out on a device of the Bruker brand, then the amount by weight of the zeolitic fractions is evaluated using the TOPAS software from the Bruker company.

Prior to adsorption, the zeolitic agglomerated material is degassed between 300 ° C and 450 ° C for a period of between 9 læ u res and 16 hours, under vacuum (pressure less than 6.7.10 ^_4 Pa). The measurement of the adsorption isotherms is then carried out on an IGA type device of the Hiden Isochema brand, taking at least 10 points at pressures between 0 and 4 bar (0.4 MPa). The mass adsorption capacity of the zeolitic agglomerated material is read on the isotherm at 25 ° C., under a pressure of 4 bar, and expressed in Ncm ³ g ¹ . The mass adsorption capacity at 25 ° C, under 4 bar (0.4 MPa), of the zeolitic agglomerated material is determined from the measurement of the adsorption isotherm of gases, such as nitrogen or oxygen, at 25 ° C.

The determination of the mean volume diameter (or “volume mean diameter”) of the zeolitic agglomerated material of the invention is carried out by analyzing the particle size distribution of a sample of adsorbent material by imaging according to the ISO 13322-2 standard. : 2006, using a conveyor belt allowing the sample to pass in front of the camera lens.

The volume mean diameter is then calculated from the particle size distribution by applying the ISO 9276-2: 2001 standard. In the present document, the term “volume mean diameter” or “size” is used for zeolitic adsorbent materials. The accuracy is on the order of 0.01 mm for the size range of the zeolite adsorbent materials of the present invention. EXAMPLES

Adsorbent A: NaLSX - Si / Al Ratio = 1.00 (according to the invention)

A homogeneous mixture is prepared consisting of 1700 g of LSX zeolite crystals of number-average diameter (d ₅ o) = 7 μm, according to the procedure described in patent application WO2009081022, with 300 g of attapulgite Zeoclay ^® , as well as the quantity of water such that the loss on ignition of the dough before shaping is 39%. The paste thus prepared is used to produce beads of zeolitic agglomerated material. A selection by sieving of the beads obtained is carried out so as to collect beads with a diameter of between 0.2 mm and 0.8 mm.

The beads are dried overnight in a ventilated oven at 80 ° C. They are then calcined for 2 hours at 550 ° C under sweeping in decarbonated air dry.

Five successive exchanges are then carried out by means of 2 M sodium chloride solutions, at a rate of 20 mL g ^-1 of solid. Each exchange is continued for 4 hours at 100 ° C., and intermediate washes are carried out, thus making it possible to eliminate the excess salt at each stage. In the final step, four washes are carried out at room temperature, at a rate of 20 mL g ^-1 . The sodium exchange rate is 99.6%.

The beads are dried overnight in a ventilated study at 80 ° C. They are then activated for 2 hours at 550 ° C. under sweeping with decarbonated dry air. Adsorbent B: NaX - Si / AI ratio = 1.24 (comparative example)

A homogeneous mixture is prepared consisting of 1700 g of crystals of zeolite X of number-average diameter (d ₅ o) = 1.8 μm and of Si / Al ratio = 1.24 as prepared in Example 1 patent US10300455 B2, with 300 g of attapulgite Zeoclay ^®, as well as the amount of water such that the loss on ignition of the dough before forming is 39%. The paste thus prepared is used to produce beads of zeolitic agglomerated material. A selection by sieving of the beads obtained is carried out so as to collect beads with a diameter of between 0.2 mm and 0.8 mm. The sodium exchange rate is 100%. The beads are dried overnight in a ventilated oven at 80 ° C. They are then calcined and activated for 2 h at 550 ° C. under bal¾ / age in decarbonated dry air.

Adsorbent C: NaMSX - Si / Al ratio = 1.13 (according to the invention)

[0102] There was prepared a homogeneous mixture of 1700 g of zeolite crystals MSX (Si / Al = 1, 13) prepared according to Table 4 Example 26 of the patent US6596256, with 300 g of attapulgite Zeoclay ^®, as well as the quantity of water such that the loss on ignition of the dough before shaping is 39%. The paste thus prepared is used to produce beads of zeolitic agglomerated material.

A selection by sieving of the beads obtained is carried out so as to collect beads with a diameter of between 0.2 mm and 0.8 mm. The beads are dried overnight in a ventilated oven at 80 ° C. They are then calcined and activated for 2 h at 550 ° C under bal¾ / age in decarbonated dry air. The sodium exchange rate is 100%.

Example 1 Mass Adsorption Isotherms of Nitrogen and Oxygen The adsorption isotherms for each of the adsorbents A, B and C are plotted according to the conditions described above, using the IGA-type apparatus of Hiden Isochema brand. The isotherms of nitrogen (N ₂ ) and oxygen (0 ₂ ) are shown on the graph in Figure 1.

It emerges very clearly that the adsorbents A, B and C have quite similar behavior with regard to the nitrogen adsorption capacities. On the other hand, it is observed, quite surprisingly, that Adsorbents A and C according to the invention exhibit oxygen adsorption capacities much lower than those observed with comparative Adsorbent B. Adsorbents A (NaLSX) and C (NaMSX) according to the invention, while being as effective as comparative Adsorbent B (NaX), as regards adsorption of nitrogen, quite unexpectedly show a lower adsorption capacity with respect to oxygen.

[0107] Thus, the zeolitic adsorbents which can be used in the context of the present invention are particularly well suited for use in medical oxygen concentrators, where the nitrogen is retained on the adsorbents, while the oxygen is much less retained. , and thus may be available more directly from an air oxygen separation apparatus.

This surprising effect is particularly visible with the adsorption capacity measurements carried out at a pressure greater than 1.5 bar (0.15 MPa), preferably greater than 2 bar (0.2 MPa), more preferably. greater than 2.5 bar (0.25 MPa), better still greater than 3 bar (0.3 MPa), more preferably greater than 3.5 bar (0.35 MPa), and typically greater than 4 bar (0, 4 MPa), which makes it possible to envisage optimal working pressures in the uses provided for in the context of the invention, in particular for medical oxygen concentrators, as already indicated above. [0109] Table 1 below collates the values of the mass nitrogen and oxygen adsorption capacities, measured at 4 bar (0.4 MPa).

- Table 1 -

[0110] It clearly emerges that the mass oxygen adsorption capacity is all the lower the lower the Si / Al molar ratio is than 1.20, preferably less than 1.15 and more preferably less than 1. , 12, while the mass nitrogen adsorption capacity remains substantially constant. There is therefore a very great advantage in using adsorbents with an Si / Al molar ratio of less than 1.20, preferably less than 1.15 and more preferably less than 1.12, that is to say adsorbents based on NaLSX or NaMSX zeolites, and preferably based on NaLSX zeolites, for the preparation of medical oxygen obtained by separation of gases from air.

Claims

1. Use of a zeolitic adsorbent material:

- based on faujasite zeolite (FAU) crystals, the Si / Al molar ratio of which is between 1.00 and 1.20, preferably between 1.00 and 1.15 and preferably 1.00 and 1.12 , terminals included, and

- With a non-zeolitic phase (PNZ) content such that 0 <PNZ <25%, preferably 0 <PNZ <20%, more preferably 0 <PNZ <15%, advantageously 0 <PNZ <10%, even more advantageously 0 <PNZ <8%, by weight relative to the total weight of the adsorbent zeolite material, for the non-cryogenic separation of industrial gases (V) PSA, particularly for the separation of nitrogen and oxygen (N _2/0 ₂ ), and more particularly for the preparation of medical oxygen from air, as well as for the industrial preparation of oxygen by (V) PSA.

Use according to Claim 1, in which the sodium content of the zeolitic adsorbent is greater than 95%, preferably greater than 97%, more preferably greater than 98%, more preferably greater than 99%, limits included, these sodium contents being expressed as percentages of exchangeable sites.

3. Use according to claim 1 or claim 2, wherein the zeolite crystals (s) which form said zeolitic adsorbent are chosen from FAU LSX type zeolite crystals (Si / Al ratio equal to 1.00), and zeolites of the FAU MSX type (Si / Al ratio corresponding to the inequation 1.00 <Si / Al <1. 20).

4. Use according to any one of the preceding claims, in which the zeolitic adsorbent material has an average volume diameter less than or equal to 7 mm, preferably between 0.05 mm and 5 mm, more preferably between 0, 2 mm and 3 mm.

5. Use according to any one of the preceding claims, in which said zeolitic adsorbent material has a bulk density of between 0.55 kg nr ³ and 0.80 kg nr ³ , preferably between 0.58 kg nr ³ and 0 , 75 kg nr ³ , more preferably between 0.60 kg nr ³ and 0.70 kg nr ³ .

6. Use according to any one of the preceding claims, wherein said zeolitic adsorbent material has a mass nitrogen (N) adsorption capacity, measured under 4 bar (0.4 MPa) at 25 ° C greater than 23 Nom. ³ g ^-1 , preferably greater than 24 Nom ³ g ^-1 , more preferably greater than 25 Ncm ³ g ^-1 , very particularly preferably greater than 26 Ncm ³ g ^-1 .

7. Use according to any one of the preceding claims, as an adsorption element in oxygen concentrators for respiratory assistance.

8. Use according to any one of the preceding claims, wherein said zeolitic material is implemented in the form of layers of adsorbents, preferably with one or two, three, or more, other layers of adsorbents.

9. Use according to the preceding claim, in which the other adsorbent (s) comprise zeolites chosen from CaLSX, LiTrLSX, 5A, NaX, LiX, LiAgLSX, LiLSX, LiCaLSX.

10. Use according to claim 8 or claim 9, using said adsorbent in a bilayer with an adsorbent based on LiLSX, forming a NaLSX / LiLSX or NaMSX / LiLSX bilayer, preferably a bi-layer or NaLSX / LiLSX. , and more preferably a NaLSX / LiLSX bilayer in which the NaLSX / LiLSX ratio is between 5/95 and 95/5, and better still between 50/50 and 95/5, by weight.

11. Breathing assistance oxygen concentrator, transportable, mobile, comprising at least one zeolitic adsorbent material used in the use according to any one of claims 1 to 10.

12. Concentrator according to claim 11, comprising a NaLSX / LiLSX or NaMSX / LiLSX bilayer, preferably a bi-layer or NaLSX / LiLSX, and more preferably a NaLSX / LiLSX bilayer in which the NaLSX / LiLSX ratio is between 5. / 95 and 95/5, and better still between 50/50 and 95/5, by weight.