Adsorbent with hierarchical structure.

Abstract

Adsorbent agglomerate comprising an internal region (7) and a superposition of layers of adsorbent particles (1), the layers of adsorbent particles (1) succeeding one another starting from said internal region (7), enveloping said internal region (7), each of the adsorbent particles (1) having a volume called particle volume, at least two layers of adsorbent particles (1) constituting hierarchical layers between them (2, 3, 4, 5), said at least two layers being the layers of adsorbent particles (1) furthest from the internal region (7), adsorbent agglomerate in which the adsorbent particles (1) constituting each of the hierarchical layers (2, 3, 4) preceding a hierarchical layer succeeding it (3, 4, 5) have an average particle volume lower than the average particle volume of the adsorbent particles (1) constituting the following hierarchical layer (3, 4, 5),a standard deviation of the particle volume values of the adsorbent particles (1) of each of the hierarchical layers being less than 20%, preferably less than 10%, preferably less than 5% relative to the average particle volume of the adsorbent particles (1) constituting said hierarchical layer. Abstract figure: Fig.1,

Description

Title of the invention: Adsorbent with hierarchical structure.

[0001] The invention belongs to the field of materials used to separate gas mixtures into a highly adsorbable fraction and a weakly adsorbable fraction.

[0002] Adsorption is widely used to purify or separate (fractionate) gases. Examples include the fractionation of "n" and "iso" paraffins, the fractionation of xylenes, alcohols, the production of nitrogen or oxygen from atmospheric air, the deballasting of CO2 from combustion gases and blast furnace gases. On the purification side, there are dryers, the purification of hydrogen or helium, the purification of methane-rich gas, the adsorption of trace impurities in many fluids (mercury, NOx, sulfur products, etc.).

[0003] Increasing the efficiency and reducing the costs of adsorption separation processes involves improving the adsorbents used in such processes and reducing cycle times. The need for reduced material transfer zones in rapid adsorption cycles requires the use of smaller adsorbent agglomerates or smaller non-agglomerated adsorbent crystals or solids. However, reducing the size of the adsorbents results in increased pressure drops across the adsorbent bed and entails a risk of fluidization of said bed. Since smaller adsorbents are also more fragile, their deterioration is likely during handling or by fluidization.

[0004] It is therefore desirable to propose an adsorbent which overcomes these drawbacks known from the prior art.

[0005] The subject of the invention is therefore an adsorbent agglomerate comprising an internal region and a superposition of layers of adsorbent particles, the layers of adsorbent particles succeeding one another starting from said internal region, enveloping said internal region, each of the adsorbent particles having a volume called particle volume, at least two layers of adsorbent particles constituting layers hierarchically arranged between them, said at least two layers being the layers of adsorbent particles furthest from the internal region, adsorbent agglomerate in which the adsorbent particles constituting each of said hierarchical layers preceding a hierarchical layer succeeding it next have an average particle volume lower than the average particle volume of the adsorbent particles constituting the next hierarchical layer,a standard deviation of the particle volume values of the adsorbent particles of each of the hierarchical layers being less than 20%, preferably less than 10%, preferably less than 5% relative to the average particle volume of the adsorbent particles constituting the hierarchical layer, considered.

[0006] According to one embodiment, the hierarchical layers are concentric. In particular, the internal region is a central region of the adsorbent agglomerate.

[0007] According to one embodiment, the adsorbent agglomerate comprises at least three hierarchical layers, preferably at least four hierarchical layers.

[0008] According to one embodiment, the adsorbent agglomerate comprises between two and fifteen hierarchical layers, terminals included, preferably between two and ten hierarchical layers, terminals included.

[0009] According to one embodiment, the thickness of each of the hierarchical layers is between 30 and 500 microns. In particular, the thickness of a hierarchical layer furthest from the internal region is between 30 and 300 microns. In particular, the thickness of the hierarchical layer preceding the next hierarchical layer furthest from the internal region is between 50 and 400 microns. In particular, the thickness of the hierarchical layer preceding the next hierarchical layer which itself precedes the hierarchical layer furthest from the internal region is between 100 and 500 microns.In particular, the hierarchical layer furthest from the internal region, the hierarchical layer preceding the next hierarchical layer furthest from the internal region and the hierarchical layer preceding the next hierarchical layer which itself precedes the hierarchical layer furthest from the internal region have the same volume or substantially the same volume.

[0010] According to one embodiment, the ratio of the volume of each of the hierarchical layers following a preceding hierarchical layer to the volume of said preceding hierarchical layer is between 100% and 350%, preferably between 150% and 250%. In particular, the ratio of the volume of a hierarchical layer furthest from the internal region to the volume of a hierarchical layer preceding the next hierarchical layer furthest from the internal region is between 170% and 250%. In particular, the ratio of the volume of the hierarchical layer preceding the next hierarchical layer furthest from the internal region to the volume of a hierarchical layer preceding the next hierarchical layer which itself precedes the next hierarchical layer furthest from the internal region is between 190% and 220%.

[0011] According to one embodiment, the ratio of the volume of a hierarchical layer furthest from the internal region to the volume of the adsorbent agglomerate is between 20% and 90%, preferably between 35% and 75%, preferably between 45% and 65%.

[0012] The inter-particle spaces of the outermost hierarchical layer(s) covering the preceding hierarchical layer(s) are advantageously wider than the inter-particle spaces of the preceding hierarchical layer(s).

[0013] According to one embodiment, the hierarchical layers represent at least 30%, preferably at least 50%, preferably at least 60% of all layers of the adsorbent agglomerate. The average volume of the adsorbent particles increases continuously between a hierarchical layer closest to the internal region and a hierarchical layer furthest from the internal region. The hierarchical layer furthest from the internal region is not covered by any other layer of adsorbent particles.

[0014] According to one embodiment, the internal region comprises an aggregate of adsorbent particles. In particular, no hierarchy of adsorbent particle layers is present in the aggregate.

[0015] According to one embodiment, the adsorbent agglomerate is substantially spherical.

[0016] According to one embodiment, the particle volume of each of the particles ad sorbent particles included in the hierarchical layers is between 4 and 4000 micron3, preferably between 40 and 400 micron3. In particular, the particle volume of each of the adsorbent particles of a hierarchical layer furthest from the internal region is between 200 and 4000 micron3. In particular, the particle volume of each of the adsorbent particles of a hierarchical layer preceding the next hierarchical layer furthest from the internal region is between 60 and 1000 micron3. In particular, the particle volume of each of the adsorbent particles of a hierarchical layer preceding the next hierarchical layer which itself precedes the next hierarchical layer furthest from the internal region is between 30 and 500 micron3.

[0017] According to one embodiment, the adsorbent particles are substantially spherical and the adsorbent particles constituting each of said hierarchical layers preceding a following hierarchical layer have an average diameter less than the average diameter of the adsorbent particles constituting said following hierarchical layer.

[0018] According to one embodiment, the adsorbent particles comprise one or more adsorbent crystals. In particular, the adsorbent particles comprise a plurality of adsorbent crystals agglomerated together. In a particular embodiment, each adsorbent particle included in the hierarchical layers consists of a single adsorbent crystal. In this embodiment, the adsorbent crystals constituting each of said hierarchical layers preceding a following hierarchical layer have an average volume less than the average volume of the adsorbent crystals constituting said following hierarchical layer.

[0019] According to one embodiment, the adsorbent particles included in the hierarchical layers comprise one or more amorphous solid(s). In particular, the adsorbent particles comprise a plurality of agglomerated amorphous solids. The amorphous solids comprise in particular an activated carbon, alumina or other metal oxides and / or silica, such as silica gel. In a particular embodiment, each adsorbent particle included in the hierarchical layers consists of a single amorphous solid. In this embodiment, the amorphous solids constituting each of said hierarchical layers preceding a following hierarchical layer have an average volume less than the average volume of the amorphous solids constituting said following hierarchical layer.

[0020] According to one embodiment, the adsorbent particles comprise a binder, in particular between 1 and 12 percent by mass (wt%) of binder, preferably between 4 and 10 percent by mass of binder.

[0021] According to one embodiment, the adsorbent agglomerate comprises a binder between the adsorbent particles, in particular between 1 and 10 percent by mass (wt%) of binder.

[0022] According to one embodiment, the adsorbent agglomerate is a zeolitic adsorbent, in particular a FAU zeolite, in particular a zeolite X, Y or A, in particular exchanged with calcium. Preferably, the adsorbent agglomerate is a zeolite of the LSX type.

[0023] According to one embodiment, the adsorbent agglomerate has a tortuosity of between 1 and 2.2.

[0024] The invention also relates to an adsorber comprising an adsorbent bed, said bed comprising a plurality of adsorbent agglomerates as described previously.

[0025] The invention also relates to a process for the separation by adsorption of a gas mixture using an adsorbent agglomerate as described above or an adsorber as described above. The process is in particular a pressure swing adsorption (PSA) process, in particular a VSA, VPSA type process. The process may also be a pressure swing adsorption process of the RPSA (Rapid PSA) type, in which the duration of the pressure cycle is typically less than one minute. The process is in particular an air separation process, for example for the production of oxygen.

[0026] The invention also relates to the use of the adsorbent agglomerate as described above or of an adsorber as described above in the processes for fractionating "n" and "iso" paraffins, for fractionating xylenes, for fractionating alcohols, and processes for purifying hydrogen or helium.

[0027] The invention also relates to a method for manufacturing an adsorbent agglomerate, in particular as described above, comprising the following steps: - providing a plurality of adsorbent particles, each of the adsorbent particles having a volume called the particle volume, - constitution of at least two batches of adsorbent particles, each batch of adsorbent particles corresponding to a targeted average particle volume of the particles which constitute it, a standard deviation of the particle volume values of the adsorbent particles of each batch being less than 20%, preferably less than 10%, preferably less than 5% relative to the targeted average particle volume of said batch, - an agglomeration step comprising the sub-steps: a) agglomeration of the adsorbent particles of a first batch into a first layer of adsorbent particles, (b) agglomeration of the adsorbent particles of the next batch into a next upper layer of adsorbent particles, covering the first layer of adsorbent particles, the targeted average particle volume of each of the batches preceding a subsequent batch being less than the targeted average particle volume of said subsequent batch.

[0028] According to one embodiment, step b) is repeated up to and including the agglomeration of the adsorbent particles of a last batch into a last layer of adsorbent particles covering the previous layer of adsorbent particles. The adsorbent agglomerate then comprises at least three layers of adsorbent particles.

[0029] According to one embodiment, the number of batches is between two and fifteen terminals inclusive, in particular between two and ten terminals inclusive.

[0030] According to one embodiment, the particle volume of the adsorbent particles provided is between 4 and 4000 micron3, preferably between 40 and 400 micron3. In particular, the particle volume of the adsorbent particles of the first batch is between 4 and 10 micron3. In particular, the particle volume of the adsorbent particles of the last batch is between 200 and 4000 micron3. In particular, the particle volume of the adsorbent particles of the batch preceding the last batch is between 60 and 1000 micron3.

[0031] According to one embodiment, the method comprises a step of providing an aggregate of adsorbent particles, and the agglomeration (agglomeration step) of the adsorbent particles of the batches formed is carried out on the aggregate. In particular, no hierarchy of layers of adsorbent particles is present in the aggregate.

[0032] According to one embodiment, the batches are formed by sieving the adsorbent particles.

[0033] According to one embodiment, the method comprises a step of feeding the adsorbent particles of the constituted batches to the agglomeration step, the feeding being done from reservoirs of adsorbent particles, each reservoir containing one of the constituted batches.

[0034] According to one embodiment, the agglomeration step is carried out in the presence of moisture or dry.

[0035] According to one embodiment, the agglomeration step comprises a sub-step of preparing each of the batches of adsorbent particles in the form of a dispersion of adsorbent particles. The dispersion comprises in particular a surfactant and a blowing agent.

[0036] According to one embodiment, the agglomeration step is carried out by fluidization. In particular, the agglomeration step comprises the sub-steps: a') spraying in a fluidized bed of a first prepared dispersion, corresponding to the first batch, until agglomeration of the adsorbent particles of the first dispersion into a first layer of adsorbent particles, b') spraying in a fluidized bed of a next prepared dispersion, corresponding to the next batch, until agglomeration of the adsorbent particles of the next dispersion into a next layer of adsorbent particles covering the first layer of adsorbent particles.

[0037] According to one embodiment, step b') is repeated up to and including the agglomeration of the adsorbent particles of a last dispersion, corresponding to the last batch, into a last layer of adsorbent particles covering the previous layer of adsorbent particles.

[0038] According to one embodiment, the fluidized bed agglomeration step is carried out in a reactor in which the prepared dispersions are supplied as a spray, in particular at a pressure of between 1 and 10 bar absolute. The pressure within the reactor is in particular between 1 and 10 bar absolute.

[0039] According to one embodiment, the fluidization is carried out by circulating a gas flow in the reactor, said gas flow being in particular at a temperature between 40 and 500°C.

[0040] Alternatively, the agglomeration step is carried out by rotating plate. In particular, the agglomeration step comprises the sub-steps: a”) arrangement on a tray of a first prepared dispersion, corresponding to the first batch, and rotation of said tray until agglomeration of the adsorbent particles of the first dispersion into a first layer of adsorbent particles, al”) possibly transferring the agglomerated adsorbent particles from said tray to another tray, b”) arranging on said tray or other tray a following dispersion prepared, corresponding to the following batch, and rotating said tray or other tray until the adsorbent particles of the following dispersion agglomerate into a following layer of adsorbent particles covering the first layer of adsorbent particles. All dispersions can be agglomerated on the same tray. Alternatively, the dispersions are each agglomerated on a different tray. The agglomeration step then includes the transfer substep al”).

[0041] According to one embodiment, step b”) and optionally step a1”) is repeated up to and including the agglomeration of the adsorbent particles of a last dispersion, corresponding to the last batch, in a final layer covering the previous layer.

[0042] According to one embodiment, the method comprises a discharge step and a step of activating the adsorbent agglomerate obtained.

[0043] [Fig.l] represents an adsorbent agglomerate according to the invention; [Fig.2] represents a first embodiment of a method for manufacturing an adsorbent agglomerate; Figures 3 and 4 each represent a variant of a second embodiment of the manufacturing method.

[0044] An adsorbent agglomerate comprises an internal region 7 and a superposition of layers of adsorbent particles 1, the layers of adsorbent particles succeeding one another starting from said internal region 7, enveloping said internal region 7, each of the adsorbent particles 1 having a volume called particle volume, at least two layers 2, 3, 4, 5 of adsorbent particles 1 constituting hierarchical layers between them, each of the hierarchical layers being constituted by a set of adsorbent particles 1 having a targeted average particle volume, a standard deviation of the particle volume values of the adsorbent particles 1 of each of the sets being less than 20%, preferably less than 10%, preferably less than 5% relative to the targeted average particle volume of said set of adsorbent particles 1, said at least two layers 2, 3, 4, 5 being the layers furthest from the internal region 7,characterized in that in each of the hierarchical layers 2, 3, 4 covered by a following hierarchical layer 3, 4, 5 which succeeds it, the targeted average particle volume is less than the targeted average particle volume of the set of adsorbent particles 1 constituting the following hierarchical layer 3, 4, 5.

[0045] The adsorbent agglomerate according to the invention comprises substantially spherical adsorbent particles 1, arranged in layers and an internal region 7, here a central region of the adsorbent agglomerate. In the embodiment of [Fig.l], a layer 2 of adsorbent particles is covered with a next upper layer 3 covering the lower layer 2, itself covered with a next upper layer 4 covering the lower layer 3, itself covered with a next upper layer 5 covering the lower layer 4. Layers 2, 3, 4 and 5 have a distance from the internal region 7 and are the layers furthest from the internal region 7. Layer 5 is the layer furthest from the internal region 7 or the outermost layer of the adsorbent agglomerate. Layers 2, 3, 4 and 5 envelop the internal region 7.Layers 2, 3, 4 and 5 follow one another starting from said internal region 7, that is to say that, in the direction going from the internal region towards an external surface of the adsorbent agglomerate, layer 2 precedes layer 3, which precedes layer 4 which itself precedes layer 5 furthest from the internal region 7. In other words, layer 5 follows layer 4, which itself follows layer 3, which itself follows layer 2.

[0046] For the purposes of the invention, a layer which immediately precedes another is called a “previous layer” and a layer which immediately follows another is called a “next layer”.

[0047] The adsorbent agglomerate of [Fig.l] thus comprises a superposition of concentric layers 2, 3, 4 and 5 of adsorbent particles 1, each of the adsorbent particles 1 having a volume called the particle volume. Each of the layers 2, 3, 4 and 5 corresponds to a targeted average particle volume of each of the adsorbent particles 1 included therein, namely that the adsorbent particles 1 included in one of the layers 2, 3, 4 and 5 each have a particle volume close to the targeted average particle volume, the particle volume being able to vary between the adsorbent particles 1 with a standard deviation of the particle volume values of the particles 1 of said layer, controlled standard deviation less than 20%, preferably less than 10%, preferably less than 5% relative to the targeted average particle volume of said layer. The layer is thus defined by the volume of the adsorbent particles 1 which constitute it.The target average particle volume corresponds to the desired volume value for the design of a layer.

[0048] Layers 2, 3, 4 and 5 constitute so-called hierarchical layers. The hierarchical layers 2, 3, 4, 5 have a hierarchy between them by obeying the following rule: the targeted average particle volume of the adsorbent particles 1 of a hierarchical layer 2, 3, 4 called lower is strictly less than the targeted average particle volume of the adsorbent particles of the following hierarchical layer 3, 4, 5 succeeding the lower layer 2, 3, 4, the following hierarchical layer 3, 4, 5 covering said lower layer 2, 3, 4.

[0049] The average particle volume of a hierarchical layer is calculated by the sum of the volumes of all the adsorbent particles of the hierarchical layer, divided by the number of adsorbent particles in said hierarchical layer. The standard deviation of the particle volumes of the particles of a hierarchical layer corresponds to the spread of the particle volume values of the particles of said hierarchical layer around the targeted average particle volume of said hierarchical layer.

[0050] In the embodiment of [Fig.l], the internal region 7 consists of an aggregate of adsorbent particles in layers having no particular hierarchy between them. The layers 2, 3, 4 and 5 are arranged around the aggregate by enveloping it.

[0051] The agglomeration of the adsorbent particles between them is optionally done using a binder.

[0052] In the embodiment shown, the adsorbent particles 1 are formed by a powder of crystals, the powder being agglomerated in order to form said adsorbent particles. The agglomeration can also be carried out using a binder. In another embodiment not shown, the adsorbent particles are formed by a powder of amorphous solids, the powder being agglomerated in order to form said adsorbent particles. The amorphous solids can consist of an activated carbon or a silica gel. The agglomeration can also be carried out using a binder.

[0053] The adsorbent particles 1 comprising agglomerated amorphous crystals or solids are also, when they are substantially spherical, called adsorbent beads. The adsorbent agglomerate with hierarchical porosity according to the invention then comprises an agglomeration of adsorbent beads arranged in concentric layers, each of said beads comprising an agglomeration of amorphous crystals or solids. In an embodiment where each adsorbent particle within the meaning of the invention consists of a single adsorbent crystal, the adsorbent agglomerate with hierarchical porosity comprises an agglomeration of crystals arranged in layers. The layers are hierarchically arranged among themselves by obeying the following rule: the average targeted volume of the crystals of a lower layer is less than the average targeted volume of the crystals of the next layer, covering said lower layer.

[0054] The inter-particle spaces 6 of the layer(s) furthest from the internal region 7, covering the lower layer(s), are advantageously wider than the inter-particle spaces of the lower layer(s). The inter-particle space measures the space between the adsorbent particles 1. The inter-particle spaces of the outermost layers open in particular onto the pore network of the adsorbent particles, in particular mesopores and micropores. Thus, the diffusion rate of the molecules between the adsorbent particles of the outermost layers is optimized. Because the outermost layers generally represent the majority of the volume of the adsorbent agglomerate, the transfer of matter is greatly improved. In the case of concentric hierarchical layers, the transfer properties of matter of the adsorbent are homogenized, thanks to the geometry of the adsorbent agglomerate obeying a central symmetry.The smaller particle volume of the lower layers makes it possible to benefit from the higher adsorption rate characteristic of small-sized adsorbent particles and thus greater selectivity. Thanks to the high volume of the adsorbent agglomerate according to the invention, relative to the adsorbent particles 1 constituting it, the disadvantages arising from the use of these small-sized adsorbent particles 1 known from the prior art, linked to the increase in pressure losses and / or linked to fluidization, are avoided. A compromise between apparently irreconcilable properties is thus found.

[0055] The particle volume within the meaning of the invention corresponds to the macroscopic volume of an adsorbent particle 1 as it can be observed and measured under a microscope, that is to say including the interstices between the elements constituting said adsorbent particle, in particular the spaces between the crystals or between the amorphous solids. The volume of the adsorbent agglomerate within the meaning of the invention corresponds to the macroscopic volume of the adsorbent agglomerate, that is to say including the inter-particle spaces 6. The average volume of the adsorbent particles 1 of a lower layer is less than the average volume of the adsorbent particles 1 of the following layer, covering said lower layer. In other words, an average characteristic dimension of the adsorbent particles 1 of the lower layer is less than an average characteristic dimension of the adsorbent particles 1 of the following layer.

[0056] The adsorbent agglomerate according to the invention may be a zeolitic adsorbent, in particular a FAU zeolite, and preferably a zeolite X. For example, zeolite X has a silica to alumina ratio of less than 1.15, preferably less than 1.1 or substantially equal to 1.0.

[0057] In the embodiment of [Fig.l], it is a calcium (Ca) exchanged faujasite type adsorbent, suitable for use after activation in an adsorbent bed of an adsorber for a pressure swing adsorption separation process, of the VSA type. However, the adsorbent agglomerate according to the invention can be used in any adsorption process, for example pressure swing adsorption (PSA), in particular a VSA (Vacuum swing adsorption) type process. The process can also be a pressure swing adsorption process of the RPSA (Rapid PSA) type, in which the duration of the pressure cycle is typically less than one minute.

[0058] [Fig.2] is a schematic representation of an example of a manufacturing process by fluidized bed agglomeration of an adsorbent agglomerate with hierarchical porosity according to the invention.

[0059] A quantity of adsorbent particles 1 is provided, and the adsorbent particles are distributed according to their particle volume, so as to constitute batches SI, S2, S3, ... Sn. The adsorbent particles 1 included in each of the batches SI, S2, S3, ... Sn all have a similar particle volume and close to a targeted average particle volume, which characterizes said batch considered. The standard deviation of the particle volume values of the adsorbent particles 1 of each of the batches SI, S2, S3, ... Sn constituted is controlled so as to be less than 20%, or even less than 10%, or even less than 5% relative to the targeted average particle volume. The remainder of the manufacturing process consists of agglomerating the adsorbent particles 1 thus distributed into batches in a hierarchical manner. The batches SI, S2, S3, ... Sn are classified in this order by increasing targeted average particle volume.

[0060] In the example of [Fig.2], the batches S1, S2, S3, ... Sn are prepared in the form of dispersions dl, d2, d3, ..dn with a surfactant and a pore-forming agent. The dispersions dl, d2, d3, dn thus prepared are then fed one after the other into a spraying device, for example a fluidization tank or reactor, device in which the dispersions dl, d2, d3, ..., dn are sprayed in a fluidized bed.

[0061] The first dispersion d1 is sprayed in a fluidized bed for the time necessary for the adsorbent particles 1 included in the first sprayed dispersion d1 to agglomerate together so as to form a first layer 2 of the adsorbent agglomerate. The agglomeration of the first layer 2 can be carried out on an aggregate. Then, the second dispersion d2 is in turn sprayed in a fluidized bed for the time necessary for the adsorbent particles 1 included in the second dispersion d2 to agglomerate into a second layer 3, covering the first layer 2. And so on until the agglomeration of the particles of a last dispersion into a last layer 5, covering the previous layer 4. The last layer 5 constitutes the external layer (or the outermost layer) of the adsorbent agglomerate.An adsorbent agglomerate of concentric layers of adsorbent particles, in which the particle volume decreases constantly from the outer layer to the innermost layers, is thus obtained.

[0062] [Fig. 3] is a schematic representation of another example of a method for manufacturing an adsorbent agglomerate with hierarchical porosity according to the invention, by agglomeration on a rotating plate. The method is similar to that of [Fig. 2], but differs in that the dispersions d1, d2, d3, ..., dn are fed, in the same order, successively one after the other, onto one or more rotating plate(s) for agglomeration. The rotating plate(s) is or are rotated for the time necessary for the agglomeration of the particles of a given dispersion into a layer, where appropriate covering the previous layer. All batches SI, S2, S3, ... Sn can be agglomerated on a single rotating plate as in the example of [Fig. 3], or each of the batches SI, S2, S3, ... Sn can be agglomerated on a different rotating plate (P_rotating 1, P_rotating 2, ... P_rotating n), as in the example of [Fig.4], with where appropriate a transfer step A1, A2 of the adsorbent particles 1 previously agglomerated on a given rotating plate to the following rotating plate.

Claims

Claims

1. Adsorbent agglomerate comprising an internal region (7) and a superposition of layers of adsorbent particles (1), the layers of adsorbent particles (1) succeeding one another starting from said internal region (7), enveloping said internal region (7), each of the adsorbent particles (1) having a volume called particle volume, at least two layers of adsorbent particles (1) constituting hierarchical layers between them (2, 3, 4, 5), said at least two layers being the layers of adsorbent particles (1) furthest from the internal region (7), adsorbent agglomerate in which the adsorbent particles (1) constituting each of said hierarchical layers (2, 3, 4) preceding a following hierarchical layer (3, 4, 5) having an average particle volume less than the average particle volume of the adsorbent particles (1) constituting said following hierarchical layer (3, 4, 5),a standard deviation of the particle volume values of the adsorbent particles (1) of each of the hierarchical layers being less than 20%, preferably less than 10%, preferably less than 5% relative to the average particle volume of the adsorbent particles (1) constituting said hierarchical layer.,

2. Adsorbent agglomerate according to the preceding claim, in which the hierarchical layers (2, 3, 4, 5) are concentric.

3. Adsorbent agglomerate according to one of the preceding claims, comprising at least three hierarchical layers (2, 3, 4, 5), preferably at least four hierarchical layers (2, 3, 4, 5).

4. Adsorbent agglomerate according to one of the preceding claims, in which the hierarchical layers (2, 3, 4, 5) represent at least 30%, preferably at least 50%, preferably at least 60% of all the layers of the adsorbent agglomerate.

5. Adsorbent agglomerate according to one of the preceding claims, in which the internal region (7) comprises an aggregate of adsorbent particles (1), in which aggregate no hierarchy of layers of adsorbent particles (1) is present.

6. Adsorbent agglomerate according to one of the preceding claims, the adsorbent agglomerate being substantially spherical.

7. Adsorbent agglomerate according to one of the preceding claims, wherein each adsorbent particle (1) included in the hierarchical layers rarchized (2, 3, 4, 5) is made up of a single crystal of adsorbent or a single amorphous solid.

8. Adsorbent agglomerate according to one of the preceding claims, the adsorbent agglomerate being a zeolitic adsorbent, in particular a FAU zeolite, in particular a zeolite X, Y or A.

9. An adsorber comprising an adsorbent bed, said bed comprising a plurality of adsorbent agglomerates according to one of the preceding claims.

10. Method for separation by adsorption of a gas mixture using an adsorbent agglomerate according to one of claims 1 to 8 or an adsorber according to claim 9.

11. A separation method according to the preceding claim, the method being an air separation method.

12. Use of an adsorbent agglomerate according to one of claims 1 to 8 or of an adsorber according to claim 9 in processes for fractionating “n” and “iso” paraffins, for fractionating xylenes, alcohols, in processes for purifying hydrogen or helium.

13. A method of manufacturing an adsorbent agglomerate comprising the following steps: - providing a plurality of adsorbent particles (1), each of the adsorbent particles (1) having a volume called particle volume, - constituting at least two batches of adsorbent particles (1), each batch of adsorbent particles (1) corresponding to a targeted average particle volume of the particles constituting it, a standard deviation of the particle volume values of the adsorbent particles of each batch being less than 20%, preferably less than 10%, preferably less than 5% relative to the targeted average particle volume of said batch, - an agglomeration step comprising the sub-steps: a) agglomerating the adsorbent particles (1) of a first batch into a first layer (2) of adsorbent particles (1), b) agglomerating the adsorbent particles (1) of the next batch into a next upper layer (3) of adsorbent particles (1),covering the first layer of adsorbent particles (1), the targeted average particle volume of each of the batches preceding a following batch being less than the targeted average particle volume of said following batch.,

14. Manufacturing method according to the preceding claim, in which the agglomeration step is carried out by fluidization or by rotating plate.

Images