ZEOLITE ADSORBENTS HAVING A HIGH EXTERNAL SURFACE AREA AND USES
THEREOF
[OOOI] The invention relates to the use of zeolite adsorbent materials in agglomerated
form comprising at least one type-A zeolite, said adsorbents having a high external
surface area characterized by nitrogen adsorption, and a high micropore volume, for gas
phase separation, in particular in pressure swing processes, either of PSA (pressure
swing adsorption) type, or of VSA (vacuum swing adsorption) type, or of VPSA (hybrid
process of the previous two), or of RPSA (rapid pressure swing adsorption) type, in
temperature swing processes of TSA (temperature swing adsorption) type and/or in
pressure and temperature swing processes of PTSA (pressure and temperature swing
adsorption) type.
[0002] The present invention also relates to a process for gas separation and
purification using said zeolite adsorbents having a high external surface area.
[0003] The invention also relates to zeolite adsorbent materials that can be used in the
context of the present invention comprising potassium and/or calcium andlor sodium.
[0004] The use of agglomerates of this type is particularly advantageous in applications
where the transfer kinetics, the volumetric adsorption capacity, which are determining
parameters for the overall efficiency and productivity of the process, and also low
pressure drops are desired.
[0005] In adsorption separation techniques, a great deal of effort has been given over
the past few years to increasing the hourly productivity of the adsorbent beds, in particular
by increasing the adsorption/desorption cycle frequency, which means that the adsorbent
used, in addition to its thermodynamic adsorption properties, must be able to become
saturated by adsorption and to release the adsorbed gas on desorption in increasingly
short time periods. The adsorbents must thus be designed so as to have the most efficient
mass transfer possible, that is to say such that the gases to be separated or to be purified
reach the adsorption sites as rapidly as possible and are also desorbed as rapidly as
possible.
[0006] Several paths have been explored in order to achieve this objective. The first
method proposed by the literature consists in decreasing the size of the adsorbent
particles. It is generally accepted that the effect of this is to enable a more rapid diffusion
of the gases in the macroporous network, the kinetic constant for transfer of matter being
inversely proportional to the square of the diameter of the particles (or equivalent
dimension, depending on the morphology of the adsorbents. Mention will for example be
made of the article "Adsorbent particle size effects in the separation of air by rapid
pressure swing adsorption", by E. Alpay et al., Chemical Engineering Science, 49(18),
3059-3075, (1 994).
[0007] Document WO 20081152319 describes the preparation, by spray-drying, of
mechanically strong adsorbents of small sizes, which are for example used in portable
concentrators of medical oxygen, as shown by document US 201310216627. The main
drawback of reducing the size of the adsorbent particles is the increase in the pressure
drops in adsorbents and the high energy consumption that is associated therewith. This is
particularly unacceptable in industrial gas production adsorption processes.
[00081 The second method consists in improving the intra-granular transfer capability of
the adsorbents, without changing the size thereof. International applications JP2157119,
JP2002068732 and W0 2002149742 describe adsorbents with improved kinetics,
obtained by conversion of the agglomeration binder into zeolite active matter and also the
associated gas separation processes, which are more efficient than with conventional
particles.
[0009] Document WO 20081051904 proposes a process for producing, by
extrusionlspheronization of beads of zeolite adsorbents based on zeolites with improved
diffusion. Document WO 20081109882 describes, for its part, the preparation of high
crush-strength adsorbents with improved mass transfer from zeolites and less than 15%
of siliceous binder introduced in colloidal form.
[0010] Application EP 1 240 939 proposes selecting, for uses in a PSA or VSA process,
adsorbents having a certain ratio between their kinetic transport constants for adsorbable
compounds in the gas phase and in the solid phase. Document US 6 328 786 defines a
minimum threshold of mechanical strength and a kinetic coefficient above which the
adsorbents are preferred for use in a PSA process. Application EP 1 048 345 describes
high-macroporosity adsorbents produced by means of a spheronization and lyophilization
technique.
[00111 A third method consists in improving the access to the adsorbent by using
various forming geometries combining both reduced active material thicknesses and
sufficiently wide fluid passage cross-sections to allow a flow with limited pressure drops.
Mention may be made of adsorbent sheets and fabrics, monoliths of bee's nest type,
foams or the like.
[00121 Document FR 2 794 993 proposes using heterogeneous beads, with an
adsorbent of peripheral layer of small thickness coating an inert core: the diffusion
distance is thus reduced, without increasing the pressure drops. This system has the
defect of having a low volumetric efficiency: a significant part of the adsorber is taken up
by matter which is inert in terms of adsorption, which has a considerable impact in terms
of facility sizes and thus of investments, or even of weight, which can be bothersome, in
5 the case of portable purificationlseparation equipment, for instance medical oxygen
concentrators.
[0013] Patent applications US 201210093715 and US 201310052126 teach that it is
possible to form monolithic zeolite structures with a hierarchical structure, by adding a
polymer to the synthesis reaction medium: as for the adsorbent sheets and fabrics, the
10 solids obtained have a very high macropore volume and a very high mesopore volume,
these solids are thus not very dense and their volumetric efficiency is low, owing to their
low volumetric adsorption capacity.
[0014] Thus, all these adsorbent geometries of various natures pose problems in terms
of relatively complex processing, of mechanical fatigue or wear resistance and of low
1s volumetric efficiency, since the active matter content is often reduced to the benefit of inert
binders or other mechanical reinforcement fibers or since the materials obtained are not
very dense.
[0015] There thus remains a need for zeolite adsorbents that are of use for the
separation and purification of gases having good transfer properties which do not have the
20 drawbacks associated with the use of the prior art adsorbents. In particular, there remains
a need for a zeolite adsorbent having greater adsorption capacities and better
adsorptionldesorption kinetics, allowing in particular a more intensive use of processes,
and in particular PSA, TSA or VPSA processes.
[0016] The inventors have now discovered that the abovementioned objectives can be
2s totally or at least partially achieved by virtue of adsorbents specifically devoted to gas
separation and purification uses as will be described now.
[0017] Thus, and according to a first aspect, the invention relates to the use, for gas
drying andlor separation, of at least one zeolite adsorbent material comprising at least one
type-A zeolite, said adsorbent having:
30 . an external surface area, measured by nitrogen adsorption and expressed in m2 per
gram of adsorbent greater than 20 rn2.g-', and preferably between 20 m2.g-' and 300
mz.g-', and more preferably between 30 m2.g-' and 250 rn2.g-' and even more
preferably between 40 m2.g-' and 200 m2.g-', and most particularly between 50 m2.g~'
and 200 m2.g-',
a non-zeolite phase (PNZ) content such that 0 < PNZ r 30%, preferably 3% r PNZ 5
25%, more preferably 3% 5 PNZ 5 20%, advantageously 5% 5 PNZ 5 20%, even better
still 7% 2 PNZ 5 18%, measured by XRD (X-ray diffraction), by weight relative to the
total weight of the adsorbent,
5 a mesopore volume of between 0.07 cm3.g-' and 0.18 cm3.g-', preferably between
0.10 cm3.g-' and 0.18 cm3.g-', and more preferably between 0.12 cm3.g-' and
0.18 cm3.g-', more preferably between 0.14 cm3.g-' and 0.18 cm3.g-'; limits included,
and an SiIAI atomic ratio of the adsorbent of between 1.0 and 2.0, preferably between
1.0 and 1.6, and entirely preferably between 1.0 and 1.4,
lo all of the measurements being carried out on the adsorbent material at least 90%
exchanged with calcium.
[0018] In the present description, the term "type-A zeolite" denotes an LTA zeolite.
According to one preferred embodiment, the type-A zeolite is a mesoporous A zeolite
chosen from 3A, 4A and 5A zeolites. The term "3A" is intended to mean a zeolite of which
is the pore opening is equal to approximately 3 8; the term "4A" is intended to mean a
zeolite of which the pore opening is equal to approximately 4 8; and the term "5A is
intended to mean a zeolite of which the pore opening is equal to approximately 5 A.
[OOl91 According to one embodiment of the invention, the zeolite adsorbent material can
also comprise one or more other zeolite(s) chosen from FAU zeolites (LSX, MSX, X, Y),
20 LTA zeolites, CHA zeolites (chabazite), HEU zeolites (clinoptilolite), and mixtures of two or
more of them, and more preferably from 3A, 4A and 5A zeolites, and mixtures of two or
, , more of them.
[0020] Other zeolites may be present in minor amounts in the adsorbents of the
invention or usable in the process of the invention. These zeolites can be considered to be
2s pollutants, in particular because they do not contribute to gas adsorption, in other words
they are inert with respect to gas adsorption. By way of nonlimiting examples, these
zeolites comprise sodalite, hydroxysodalite, zeolite P, and other zeolites that are inert with
respect to gas adsorption.
[00211 The various types of zeolites present in the zeolite adsorbent material are
30 determined by XRD. The amount of zeolites is also measured by XRD and is expressed
as % by weight relative to the total weight of the zeolite adsorbent material.
100221 Consequently, in the present invention, the term "non-zeolite phase" (or "PNZ)
denotes any phase present in the adsorbent material, other than the zeolite(s) defined
above, called "zeolite phase" or "PZ. The amount of non-zeolite phase is expressed by
the amount to be added to the zeolite phase of the adsorbent to make the total up to
loo%, in other words:
%PNZ = 100 - %PZ,
where %PNZ represents the percentage by weight of PNZ and %PZ the percentage by
weight of zeolite phase, relative to the total weight of the adsorbent.
[0023] The expression "adsorbent at least 90% exchanged with calcium" is intended to
mean that at least 90% of the exchangeable catatonic sites of the zeolite phase are taken
up by calcium cations.
[0024] This zeolite adsorbent material at least 90% exchanged with calcium can be
obtained and preferably is obtained according to the following protocol: the zeolite
adsorbent material to be exchanged with calcium is introduced into a solution of calcium
chloride at 0.5 mol of CaCI2 per liter, at 70°C, for 2 hours, with a liquid-to-solid ratio of 10
m1.g.'. The operation is repeated n times, n being at least equal to 1, preferably at least
equal to 2, preferably at least equal to 3, more preferably at least equal to 4.
[0025] The solids resulting from the exchange operations n-I and n are successively
washed four times by immersion in water in a proportion of 20 m1.g-' in order to remove
the excess salt, and then dried for 12 hours at 80°C in air, before being analyzed by X-ray
fluorescence. If the weight perceniage of calcium oxide of the zeoliie adsorbent material,
between the exchange operations n-I and n, is stable at + I%, said zeolite adsorbent
material is considered to be "in its form at least 90% exchanged with calcium". Where
appropriate, additional exchanges are carried out as described above until stability of the
weight percentage of calcium oxide of + 1 % is obtained.
I00261 It will in particular be possible to carry out successive batchwise cationic
exchanges, with a large excess of calcium chloride, until this weight percentage of calcium
oxide of the zeolite adsorbent material, determined by X-ray fluorescence chemical
analysis, is stable at + 1%. This method of measurement is explained below in the
description.
[002a The SiIAI atomic ratio of the zeolite adsorbent material is measured by X-ray
fluorescence elemental chemical analysis, a technique well known to those skilled in the
art and explained below in the description.
[0028] If necessary, the calcium exchange is carried out before analyses according to
the procedure described in detail above. On the basis of the micropore volume according
to Dubinin-Raduskevitch measured on the zeolite adsorbent material exchanged with
calcium, it is therefore possible to calculate an overall Dubinin-Raduskevitch volume of A
zeolite(s), which is PNZ-weighted.
[0029] The term "Vmicro" is intended to mean the micropore volume of the zeolite
adsorbent material, the measurement technique of which is explained below. The term
"Vmeso" is intended to mean the mesopore volume of the zeolite adsorbent material, the
measurement technique of which is explained below.
s [0030] According to one preferred embodiment, said at least one zeolite adsorbent
material that can be used in the context of the present invention has a (Vmicro -
Vmeso)Nmicro ratio of between -0.3 and 1.0, limits not included, preferably between -0.1
and 0.9, limits not included, preferably between 0 and 0.9, limits not included, more
preferably between 0.2 and 0.8, limits not included, more preferably between 0.4 and 0.8,
lo limits not included, preferably between 0.6 and 0.8, 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, all of the
measurements being carried out on the adsorbent material at least 90% exchanged with
calcium.
is [0031] According to yet another embodiment, said at least one zeolite adsorbent
material has a micropore volume (Vmicro, or else Dubinin-Raduskevitch volume),
expressed in cm3 per gram of adsorbent material, of between 0.160 cm3.g-' and 0.280
cm3.g-', preferably between 0.180 cm3.g-' and 0.280 cm3.g-', preferably between 0.200
cm3.g-' and 0.280 cm3.g-', more preferably 0.220 cm3.g-' and 0.280 cm3.g-', measured on
20 the adsorbent material at least 90% exchanged with calcium.
[0032] The total volume of the macropores and mesopores of the zeolite adsorbent
materials that can be used in the context of the present invention, measured by mercury
intrusion, is advantageously between 0.15 cm3.g-' and 0.50 cm3.g-', preferably between
0.20 cm3.g-' and 0.40 cm3.g-' and very preferably between 0.20 cm3.g-' and 0.35 cm3.g-
25 ',the measurements being carried out on the adsorbent material at least 90% exchanged
with calcium.
[00331 The volume fraction of the macropores of the zeolite adsorbent material that can
be used in the context of the present invention is preferably between 0.20 and 1 .OO of the
total volume of the macropores and mesopores, very preferably between 0.40 and 0.80
30 and even more preferably between 0.45 and 0.65, limits included, the measurements
being carried out on the zeolite adsorbent material at least 90% exchanged with calcium.
[0034] The zeolite adsorbent materials that can be used in the context of the present
invention are either known or can be prepared using known procedures, or else are novel
and in this respect are an integral part of the present invention.
[0035] According to yet another preferred embodiment, the use according to the
invention employs a zeolite adsorbent material comprising at least one mesoporous A
zeolite. The term "mesoporous" is intended to mean a zeolite which has, together with the
microporosity inherent in the structure of the zeolite, internal cavities of nanometric size
(mesoporosity), easily identifiable by observation using a transmission electron
microscope (TEM), as described for example in US 7 785 563.
I00361 More specifically, said A zeolite of the zeolite adsorbent material is a mesoporous
A zeolite, that is to say a zeolite having an external surface area, defined by the t-plot
method described below, of between 40 m2.g-' and 400 m2.g-', preferably between
60 m2.g-' and 200 m2.g-', limits included. By extension, for the purposes of the present
invention, a "non-mesoporous zeolite" is a zeolite optionally having an external surface
area, defined by the t-plot method described below, of strictly less than 40 m2.g~'.
[0037] In particular, the zeolite adsorbent materials that can be used in the context of
the present invention comprise at least one A zeolite, in which said at least one A zeolite
has an Si/AI ratio equal to 1 .OO +/- 0.05, said SiIAI ratio being measured by solid silicon 29
nuclear magnetic resonance of ("Si NMR), according to the techniques well known to
those skilled in the art
[0038] The SilAl ratio of each of the meolite(s) present in the adsorbent is also measured
by NMR of the solid.
[0039] According to one preferred embodiment, the A zeolite of the zeolite adsorbent
material is in the form of crystals, the number-average diameter of which, measured using
a scanning electron microscope (SEM), is less than 20vm, preferably between 0.1 pm
and 20 vm, preferably between 0.1 and 10 pm, preferably between 0.5 pm and 10 vm,
more preferably between 0.5 pm and 5 pm, limits included.
[0040] According to yet another preferred embodiment, said zeolite adsorbent material
comprises at least one cation chosen from the ions of groups IA, IIA, IIIA, IB, llB and lllB
of the periodic table, the trivalent ions of the lanthanide or rare earth series, the zinc(ll)
ion, the silver(1) ion, the cupric (11) ion, the chromium(lll) ion, the ferric (111) ion, the
ammonium ion and/or the hydronium ion, the preferred ions being calcium, lithium,
sodium, potassium, barium, cesium, strontium, zinc and rare-earth ions and more
preferably sodium, calcium and potassium ions, and mixtures thereof.
[0041] According to the present invention, the zeolite adsorbent materials described
above are most particularly suitable and effective in processes for gas-phase separation
andlor drying, in particular in pressure swing processes, either of PSA type, or of VSA
type, or of VPSA type, or of RPSA type, or of TSA type andlor in processes of PTSA type.
[0042] More specifically, the present invention relates to the use of at least one zeolite
adsorbent material comprising at least one A zeolite, as defined above, for gas separation
andlor drying, more generally simply called "gas separation". The term "gas separation" is
intended to mean drying, purification, pre-purification, elimination, and other separations
of one or more gas compounds present in a mixture of one or more gas compounds. More
specifically, the term "drying" is intended to mean the selective trapping, by adsorption
with the zeolite adsorbent material, of the water molecules present in a gaseous medium.
The term "drying" is thus included in the definition of the present description of the term
"separation", the term "drying" having to be interpreted as the separation, from a gaseous
medium, of the water molecules included in said gaseous medium.
[0043] According to one preferred aspect of the present invention, the zeolite adsorbent
materials that can be used for the gas purification and drying are materials which only
generate a slight pressure drop or pressure drops that are acceptable for the
abovementioned uses.
[0044] Preference is thus given to the agglomerated and formed zeolite adsorbent
materials prepared according to any techniques known to those skilled in the art, such as
extrusion, compacting, agglomeration on a granulating plate or granulating drum,
atomization and the like. The proportions of agglomeration binder and of zeolites used are
typically those of the prior art, that is to say between 5 parts and 30 parts by weight of
binder per 95 parts to 70 parts by weight of zeolite.
[0045] The zeolite adsorbent material that can be used in the context of the present
invention, whether it is in the form of balls, extruded pieces or the like, generally has a
volume mean diameter, or a mean length (largest dimension when it is not spherical), of
less than or equal to 7 mm, preferably between 0.05 mm and 7 mm, more preferably
between 0.2 mm and 5.0 mm and more preferentially between 0.2 mm and 2.5 mm.
[0046] The zeolite adsorbent materials that are of use in the context of the present
invention also have mechanical properties that are most particularly suitable for the
applications to which they are intended, that is to say:
either a bulk crush strength (BCS) in a bed, measured according to standard ASTM
7084-04, of between 0.5 MPa and 3 MPa, preferably between 0.75 MPa and 2.5 MPa,
for a material having a volume mean diameter (D50) or a length (largest dimension
when the material is not spherical), of less than 1 mm, limits included, - or a single pellet crush strength, measured according to standards ASTM D 4179
(201 1) and ASTM D 6175 (2013), of between 0.5 daN and 30 daN, preferably between
1 daN and 20 daN, for a material having a volume mean diameter (D50) or a length
(largest dimension when the material is not spherical), greater than or equal to 1 mm,
limits included.
[0047] According to another preferred embodiment, the use according to the invention
uses at least one zeolite adsorbent material having a high volumetric adsorption capacity,
s that is to say a volumetric micropore volume expressed in ~ m ~ . comf a-d~so rbent material
at least 90% exchanged with calcium, said micropore volumetric volume being greater
than 0.01 ~ m ~ . c mp-re~fe,r ably greater than 0.02 ~ m ~ . c mm-o~re, preferably greater than
0.03 ~ m ~ . c mm-o~re, preferably greater than 0.04 ~ m ~ . c mm-o~re, preferably greater than
0.05 ~ m ~ . c m - ~ .
10 [0048] According to yet another embodiment, the use according to the invention
preferably uses at least one zeolite adsorbent material having a loss on ignition,
measured at 950°C according to standard NF EN 196-2, of between 0% et 5%, preferably
between 0% and 3% by weight.
[0049] In particular, the present invention relates to the use of at least one zeolite
is adsorbent material as has just been defined, for drying cracked gases. The term "cracked
gases" is defined as the gases obtained by cracking (for example steam cracking,
catalytic cracking, catalytic dehydrogenation and the like) of hydrocarbon feed stocks, at
high temperature (> 350°C), said feed stocks possibly being, for example, and in a nonlimiting
manner, LPG, ethane, naphtha, diesel oil, vacuum distillate, and the like. TSA
20 processes are most particularly suitable for these cracked-gas-drying uses. It is in
particular preferred to use, for these types of applications, the adsorbent materials
comprising at least one 3A zeolite, which is preferably mesoporous.
[0050] For these types of applications, preference is given to a zeolite adsorbent
material of which the volume mean diameter (or the longest length) is between 0.5 mm
2s and 7.0 mm, preferably between 1.0 mm and 7.0 mm, and more preferably between 1.5
mm and 7.0 mm, limits included.
[00511 According to another embodiment, the present invention relates to the use of at
least one zeolite adsorbent material as has just been defined, for drying andlor separating
refrigerant fluids, in particular HFC and HFO, such as for example and in a non-limiting
30 manner, 1, I, I,2 -tetrafluoroethane, 2,3,3,3-tetrafluoropropenea,n d the like, for instance
those cited in document WO 20071144632. TSA processes are most particularly suitable
for these refrigerant-fluid-drying uses. It is in particular preferred to use, for these types of
applications, the adsorbent materials comprising at least one A zeolite, which is preferably
mesoporous, chosen from 3A, 4A and 5A zeolites, and mixtures thereof.
100521 For these types of applications, preference is given to a zeolite adsorbent
material of which the volume mean diameter (or the longest length) is between 0.3 mm
and 7.0 mm, preferably between 0.8 mm and 5.0 mm, more preferably between I .0 mm
and 4.0 mm, limits included.
100531 According to another embodiment, the present invention relates to the use of at
least one zeolite adsorbent material as has just been defined, for drying alcohols, and in
particular ethanol, and in particular according to pressure swing (PSA) processes. It is in
particular preferred to use, for these types of applications, adsorbent materials comprising
at least one 3A zeolite, which is preferably mesoporous.
[0054] For these types of applications, preference is given to a zeolite adsorbent
material of which the volume mean diameter (or the longest length) is between 0.3 mm
and 7.0 mm, preferably between 0.8 mm and 5.0 mm, and more preferably between
2.0 mm and 5.0 mm, limits included.
[0055] According to another embodiment, the present invention relates to the use of ai
least one zeolite adsorbent material as has just been defined, for drying andlor separating
air and industrial gases. TSA processes are most particularly suitable for these uses for
drying air and industrial gases. It is in particular preferred to use, for these types of
applications, the adsohsnt materials comprising at least one A zeolite, which is preferably
mesoporous, chosen from 3A, 4A and 5A zeolites, and mixtures thereof.
[0056] A most particularly advantageous application is the separation of nitrogen and
oxygen from the air, according to a PSA or VPSA process, using a zeolite adsorbent
material as previously defined, and comprising at least one 5A zeolite, which is preferably
mesoporous.
I00571 For these types of applications, preference is given to a zeolite adsorbent
material of which the volume mean diameter (or the longest length) is between 0.3 mm
and 7.0 mm, preferably between 0.8 mm and 5.0 mm, and more preferably between
1 .O mm and 5.0 mm, limits included.
[0058] According to another embodiment, the present invention relates to the use of at
least one zeolite adsorbent material as has just been defined, for purifying olefins, in
particular for removing impurities, and preferably for removing oxygen-bearing impurities,
and more preferably for removing methanol, in particular according to TSA adsorption
processes. It is in particular preferred to use, for these types of applications, the adsorbent
materials comprising at least one A zeolite, which is preferably mesoporous, chosen from
3A, 4A and 5A zeolites, and mixtures thereof, preferably from 3A and 4A zeolites, and
mixtures thereof.
[0059] For these types of applications, preference is given to a zeolite adsorbent
material of which the volume mean diameter (or the longest length) is between 0.3 mm
and 7.0 mm, preferably between 0.8 mm and 5.0 mm, and more preferably between
2.0 mm and 4.0 mm, limits included.
5 [0065] According to another embodiment, the present invention relates to the use of at
least one zeolite adsorbent material as has just been defined, for drying andlor separating
natural gas, in particular for removing impurities and preferably for removing carbon
dioxide, hydrogen sulfide andlor light mercaptans (containing one or two carbon atoms:
CISH, C2SH), in particular according to TSA, PSA or PTSA adsorption processes. It is in
10 particular preferred to use, for these types of applications, the adsorbent materials
comprising at least one A zeolite, which is preferably mesoporous, chosen from 3A, 4A
and 5A zeolites, and mixtures thereof.
[5061] For these types of applications, preference is given to a zeolite adsorbent
material of which the volume mean diameter (or the longest length) is between 0.3 mm
is and 7.0 mm, preferably between 0.8 mm and 5.0 mm, and more preferably between
2.0 mm and 5.0 mm, limits included.
[0062] According to another embodiment, the present invention relates to the use of at
least one zeolite adsorbent material as has just been defined, for separating paraffins,
preferably in the gas phase, in particular according to TSA adsorption processes. It is in
20 particular preferred to use, for these types of applications, the adsorbent materials
comprising at least one 5A zeolite, which is preferably mesoporous.
I00631 For these types of applications, preference is given to a zeolite adsorbent
material of which the volume mean diameter (or the longest length) is between 0.3 mm
and 7.0 mm, preferably between 0.8 mm and 5.0 mm, and more preferably between
2s 2.0 mm and 5.0 mm, limits included.
I00641 According to another embodiment, the invention relates to the use of at least one
zeolite adsorbent material as has just been defined, for drying andlor purifiying syngas. An
example of a process for purifying syngas is described in patent EP 1 312 406. The
syngases targeted here are in particular syngases that are based on hydrogen and carbon
30 monoxide andlor on hydrogen and nitrogen (syngas for hydrogen production), and more
particularly mixtures of hydrogen and carbon monoxide andlor of hydrogen and nitrogen,
these syngases possibly also containing, or being polluted with, carbon dioxide and one
or more possible other impurities, for instance, and in a nonlimiting manner, one or more
impurities chosen from nitrogen, carbon monoxide, oxygen, ammonia, hydrocarbons and
oxygen-comprising derivatives, in particular alkanes, in particular methane, alcohols, in
particular methanol, and others.
[0065] The use according to the present invention is thus most particularly suitable for
removing the nitrogen, the carbon monoxide, the carbon dioxide, the methane, and other
impurities, preferably by pressure swing adsorption (PSA) processes, for hydrogen
production. For these types of applications, adsorbent materials comprising at least one A
zeolite, which is preferably mesoporous, chosen from 3A, 4A and 5A zeolites, and
mixtures thereof, are preferred.
[0066] For these types of applications, preference is given to a zeolite adsorbent
material of which the volume mean diameter (or the longest length) is between 0.3 mm
and 7 mm, preferably between 0.8 mm and 5.0 mm, and more preferably between 1.0 mm
and 3.0 mm, limits included.
100671 According to another aspect, the invention relates to a zeolite adsorbent material
having:
an SilAl ratio of said adsorbent, such that 1.0 5 SiIAI < 2.0, preferably 1.0 5 SiIAl 5 1.6,
more preferably 1 5 SiIAI 5 1.4,
a mesopore volume of between 0.07 cm3.g-I and 0.18 cm3.g-', preferably between
0.10 cm3.g-' and 0.18 cm3.g", and more preferably between 0.12 cm3.g-' and
0.18 cm3.g-', more preferably between 0.14 cm3.g-' and 0.18 cm3.g-l, limits included,
* of ratio (Vmicro - Vmeso)Nmicro between -0.3 and 1 .O, limits not included, preferably -
0.1 and 0.9, limits not included, preferably 0 and 0.9, limits not included, more
preferably between 0.2 and 0.8, limits not included, more preferably between 0.4 and
0.8, limits not included, preferably between 0.6 and 0.8, 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 < PNZ 5 30%, preferably 3% 5 PNZ r
25%, more preferably 3% 5 PNZ 5 20%, advantageously 5% 5 PNZ 5 20%, even better
still 7% 5 PNZ 5 18%, measured by XRD, by weight relative to the total weight of the
zeolite adsorbent material,
all of the measurements being carried out on the zeolite adsorbent material at least 90%
exchanged with calcium.
[0068] The zeolite adsorbent material of the invention as has just been defined is a
novel material in that it results from the agglomeration, with a binder as described below,
of at least one mesoporous A zeolite, where the term "mesoporous", already previously
defined, denotes a zeolite which has, together with the microporosity inherent in the
structure of the zeolite, internal cavities of nanometric size (mesoporosity), easily
identifiable by observation using a transmission electron microscope (TEM), as described
for example in US 7 785 563.
[0069] More specifically, the zeolite adsorbent material comprises at least one
mesoporous A zeolite, that is to say a zeolite having an external surface area, defined by
the t-plot method described below, of between 40 m2.g-' and 400 m2.g-', preferably
between 60 m2.g-' and 200 mZ.g-', limits included.
[0070] In addition, the zeolite adsorbent material according to the invention comprises at
least one metal chosen from potassium, sodium and calcium, and mixtures of two or more
of these metals, preferably two metals chosen from potassium, sodium and calcium.
[0071] These characteristics make the zeolite adsorbent material according to the
invention particularly suitable for gas treatments, as was described above in the present
description.
[0072j The zeolite adsorbent material according to the invention can be in all the forms
known to those skilled in the art, and preferably in simple geometric forms, that is to say in
granular forms, for example of ball or rod type, that is to say in spherical or cylindrical
forms, respectively. Such simple forms are most particularly suitable since they are easy
to process, in particular because of their shapes and their sizes that are compatible with
existing technologies. In addition, these simple forms mean that the processes used
consume low amounts of energy, since the zeolite adsorbent material generates few
pressure drops, and has improved transfer properties.
[0073] The zeolite adsorbent material according to the invention can be prepared
according to any method known to those skilled in the art, and in particular, and
preferably, using the process for preparing mesoporous A as described for example in
WO 20071043731 and by agglomerating the crystals obtained with at least one organic or
mineral binder, preferably mineral binder, more preferably a binder chosen from
zeolitizable or non-zeolitizable clays, and in particular from kaolins, kaolinites, nacrites,
dickites, halloysites, attapulgites, sepiolites, montmorillonites, bentonites, illites and
metakaolins, and also mixtures of two or more of these clays, in any proportions.
[0074] The agglomeration and the forming can be carried out according to all of the
techniques known to those skilled in the art, such as extrusion, compacting,
agglomeration on a granulating plate or granulating drum, atomization and the like. These
various techniques have the advantage of allowing the preparation of adsorbent materials
according to the invention which have the sizes and shapes previously described and are
most particularly suitable for gas treatments.
[0075] The proportions of agglomeration binder (for example clays, as indicated above)
and of zeolite(s) used for the preparation are typically those of the prior art, and vary
according to the desired PNZ content and the degree of zeolitization of the binder. These
proportions can be easily calculated by those skilled in the art specializing in the synthesis
of zeolite agglomerates.
[0076] The agglomerates of the zeolite adsorbent materials, whether they are in the
form of balls, extruded pieces or the like, generally have a volume mean diameter, or a
mean length (largest dimension when they are not spherical), of less than or equal to 7
mm, preferably between 0.05 mm and 7 mm, more preferably between 0.2 mm and 5 mm
and more preferentially between 0.2 mm and 2.5 mm.
[0077] The process for preparing the zeolite adsorbent materials according to the
invention is readily adaptable from the preparation processes known to those skilled in the
art, as already indicated, the use of at least one mesoporous A zeolite not substantially
modifying these known processes, which means that the preparation process is a process
that is easy, rapid and economical to implement and thus easily industrializable with a
minimum of steps.
[0078] The zeolite adsorbent material of the invention preferably comprises at the same
time macropores, mesopores and micropores. The term "ma~oporesi"s intended to mean
pores of which the opening is greater than 50 nm, preferably between 50 nm and 400 nm.
The term "mesopores" is intended to mean pores of which the opening is between 2 nm
and 50 nm, limits not included. The term "micropores" is intended to mean pores of which
the opening is less than 2 nm.
I00791 According to one preferred embodiment, the zeolite adsorbent material according
to the present invention has a micropore volume (Dubinin-Raduskevitch volume),
expressed in cm3 per gram of zeolite adsorbent material, of between 0.160 cm3.g-' and
0.280 cm3.g-', preferably between 0.180 cm3.g-' and 0.280 cm3.g-', more preferably
between 0.200 cm3.g-' and 0.280 cm3.g-', advantageously between 0.220 cm3.g-' and
0.280 cm3.g-', said micropore volume being measured on the zeolite adsorbent material at
least 90% exchanged with calcium.
[00801 The total volume of the macropores and mesopores of the zeolite adsorbent
materials according to the invention, measured by mercury intrusion, is advantageously
between 0.15 cm3.g-' and 0.50 cm3.g-', preferably between 0.20 cm3.g-' and 0.40 cm3.g-'
and very preferably between 0.20 cm3.g-' and 0.35 cm3.g-',the measurements being
carried out on the adsorbent material at least 90% exchanged with calcium.
[0081] The volume fraction of the macropores of the zeolite adsorbent material is
preferably between 0.2 and 1.0 of the total volume of the macropores and mesopores,
very preferably between 0.4 and 0.8 and even more preferably between 0.45 and 0.65,
limits included, the measurements being carried out on the zeolite adsorbent material at
5 least 90% exchanged with calcium.
I00821 The size of the A zeolite crystals used to prepare the zeolite adsorbent material
of the invention and also the size of the A zeolite elements in the zeolite adsorbent
material are measured by observation under a scanning electron microscope (SEM).
Preferably, the mean diameter of the A zeolite crystals is between 0.1 pm and 20 pm,
10 preferably between 0.5 pm and 20 pm, and more preferably between 0.5 pm and 10 pm.
The SEM observation also makes it possible to confirm the presence of non-zeolite phase
comprising for example residual binder (not converted during the optional zeolitization
step) or any other amorphous phase in the agglomerates.
[0083] According to one preferred embodiment, the zeolite adsorbent material according
15 to the invention has an external surface area, measured by nitrogen adsorption and
expressed in m2 per gram of adsorbent, greater than 20 m2.g-', and preferably between
20 m2.g-' and 300 m2.g-', and more preferably between 30 m2.g-' and 250 m2.g-' and more
preferably between 40 rn2.g-' and 200 m2.g-', and most preferably between 50 rn2.g-' and
200 m2.g-', the measurements being carried out on the zeolite adsorbent material at least
20 90% exchanged with calcium.
[0084] According to one preferred embodiment, the zeolite adsorbent material according
to the invention has a high volumetric adsorption capacity, that is to say a volumetric
micropore volume expressed in cm3.& of zeolite adsorbent material at least 90%
exchanged with calcium, said volumetric micropore volume being greater than
2s 0.01 cm?~m-~p,re ferably greater than 0.02 ~ m ~ . c mm- ~or,e preferably greater than
0.03 ~rn~.cm-~,rnoprref erably greater than 0.04 ~ m ~ . c r nm-o~r,e preferably greater than
0.05 ~ m ~ . c m - ~ .
[0085] According to one preferred embodiment, the zeolite adsorbent material according
to the invention comprises at least one mesoporous A zeolite as defined above, said at
30 least one zeolite having an SiIAl ratio equal to 4.00 +I- 0.05, the measurements being
carried out on the zeolite adsorbent material at least 90% exchanged with calcium.
[0086] According to yet another preferred embodiment, said zeolite adsorbent material
comprises at least one cation chosen from the ions of groups IA, IIA, IIIA, IB, llB and lllB
of the periodic table, the trivalent ions of the lanthanide or rare earth series, the zinc(ll)
35 ion, the silver(1) ion, the cupric (11) ion, the chromium(lll) ion, the ferric (Ill) ion, the
ammonium ion and/or the hydronium ion, the preferred ions being calcium, lithium,
sodium, potassium, barium, cesium, strontium, zinc and rare-earth ions and more
preferably sodium, calcium and potassium ions.
[0087] According to a further preferred aspect, the zeolite adsorbent material according
5 to the invention does not have a zeolite structure other than the A (LTA) structure. The
expression "does not have a zeolite structure other than the A structure" is intended to
mean that an XRD (X-ray diffraction) analysis of the adsorbent material according to the
invention does not make it possible to detect more than 5% by weight, preferably not more
than 2% by weight, limits included, of zeolite structure other than an LTA structure,
10 relative to the total weight of the zeolite adsorbent material.
[0088] According to yet another preferred embodiment, the material according to the
present invention has a total macropore and mesopore volume, measured by mercury
intrusion, of between 0.15 cm3.g-' and 0.50 cm3.g-', and a macropore volume fraction of
between 0.2 and 1 time said total macropore and mesopore volume, preferably between
15 0.4 and 0.8, limits included, the measurements being carried out on the adsorbent
material at least 90% exchanged with calcium.
Characterization techniques
[0089] The physical properties of the zeolite adsorbent materials are evaluated by the
20 methods known to those skilled in the art, the maln ones of which are recalled below.
Zeolite crystal particle size:
, , [0090] The estimation of the number-average diameter of the A zeolite crystals
contained in the zeolite adsorbent materials, and which are used for preparing said zeolite
25 adsorbent material, is carried out by observation under a scanning electron microscope
(SEM).
[0091] In order to estimate the size of the zeolite crystals on the samples, a set of
images is taken at a magnification of at least 5000. The diameter of at least 200 crystals is
then measured using dedicated software, for example the Smile View software published
30 by LoGraMi. The accuracy is of the order of 3%.
Zeolite adsorbent particle size
[0092] The volume mean diameter (or "volume-average diameter") of the zeolite
adsorbent material of the process according to the invention is determined by analysis of
3s the particle size distribution of a sample of adsorbent material by imaging according to
standard IS0 13322-2:2006, using a conveyor belt that allows the sample to pass in front
of the objective of the camera.
[0093] The volume-average diameter is then calculated from the particle size distribution
by applying standard IS0 9276-2:2001. In the present document, the name "volumes
average diameter" or else "size" is used for the zeolite adsorbent materials. The accuracy
is of the order of 0.01 mm for the size range of the adsorbent materials which may be
used in the context of the present invention.
Chemical analysis of the zeolite adsorbent materials - SilAl ratio and degree of
exchange:
[0094] An elemental chemical analysis of a zeolite adsorbent material described above
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 1SO 12677: 201 1 on a wavelengthdispersive
spectrometer (WDXRF), for example the Tiger 58 machine from the company
Bruker.
[0095] X-ray fluorescence is a non4estructive spectral technique which exploits the
phoialuminescence of atoms in the x-ray range, to estabiish the elemental composition of
a sample. Excitation of the atoms, generally with an x-ray beam or by electron
bombardment, generates specific radiations after returning to the ground state of the
atom. A measurement uncertainty of less than 0.4% by weight is conventionally obtained
after calibration for each oxide.
[0096] Other methods of analysis are for example illustrated by the atomic absorption
spectrometry (AAS) and inductively coupled plasma atomic emission spectrometry (ICPAES)
methods described in standards NF EN IS0 21587-3 or NF EN IS0 21079-3 on an
apparatus of for example Perkin Elmer 4300DV type.
[0097] 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
quantitatively and qualitatively. After calibration for each oxide SiO, and AI,O,, and also
the various oxides (such as those originating from the exchangeable cations, for example
calcium), a measurement uncertainty of less than 0.4% by weight is conventionally
obtained.
[0098] Thus, the elemental chemical analyses described above make it possible to
verify both the SiIAI ratio of the zeolite used within the zeolite adsorbent ~nateriaal nd the
SiIAI ratio of the zeolite adsorbent material. In the description of the present invention, the
measurement uncertainty for the SiIAI ratio is +5%. The measurement of the SiIAI ratio of
the zeolite present in the adsorbent material can also be carried out by solid silicon
nuclear magnetic resonance (NMR) spectroscopy.
[0099] The quality of the ion exchange is linked to the number of moles of the cation in
question in the zeolite adsorbent material after exchange. More specifically, the degree of
exchange with a given cation is estimated by evaluating the ratio between the number of
moles of said cation and the number of moles of all of the exchangeable cations. The
respective amounts of each of the cations are evaluated by chemical analysis of the
corresponding cations. For example, the degree of exchange with the calcium ions is
estimated by evaluating the ratio between the total number of Ca2' cations and the total
number of exchangeable cations (for example Ca2+, K', Li', ~a", Cs', Na', etc..), the
amount of each of the cations being evaluated by chemical analysis of the corresponding
oxides (Na20, CaO, K20, BaO, Li20, Cs20, etc.). This method of calculation also takes
into account the possible oxides present in the residual binder of the zeolite adsorbent
material. However, the amount of such oxides is considered to be minor compared with
the oxides originating from the cations of the exchangeable sites of the zeolite(s) of the
zeoliie adsorbent material according to the invention.
Macropore and mesopore volume
[001001 The macropore and mesopore volume are measured by mercury intrusion
porosimetry. A Micromeritics ~ u t o p o r9e5~0 0 mercury porosimeter is used to analyze the
distribution of the pore volume contained in the macropores and in the mesopores.
[00101] The experimental method, described in the operating manual for the apparatus
which refers to standard ASTM D4284-83, consists in placing a pre-weighed sample of
zeolite adsorbent material to be measured (of known loss on ignition) in a porosimeter
cell, then, after prior degassing (discharge pressure of 30 pmHg for at least 10 min), in
filling the cell with mercury at a given pressure (0.0036 MPa), and then in applying an
increasing pressure in steps up to 400 MPa in order to gradually cause the mercury to
penetrate into the porous network of the sample.
[00102] In the present document, the macropore and mesopore volumes of the zeolite
adsorbent materials, expressed in cm3.g~', are thus measured by mercury intrusion and
related to the weight of the sample in anhydrous equivalent, that is to say the weight of
said material corrected for the loss on ignition. The measurements are carried out on the
zeolite adsorbent material at least 90% exchanged with calcium.
Mechanical strength of the zeolite adsorbent materials:
[00103] The bulk crush strength in a bed of the zeolite adsorbent materials as described
in the present invention is characterized according to standard ASTM 7084-04. The grain
crush strengths are determined with a "grain crushing strength" apparatus sold by Vinci
5 Technologies, according to standards ASTM D 4179 and D 6175.
Micropore volume measurement:
[Of001 The micropore volume measurement is estimated by conventional methods such
as Dubinin-Raduskevitch volume measurements (adsorption of liquid nitrogen at 77 K or
lo of liquid argon at 87 K).
[OlOl] The Dubinin-Raduskevitch volume is determined from the gas, such as nitrogen
or argon, adsorption isotherm measurement, at its liquefaction temperature, as a function
of the pore openings of the zeolite: nitrogen will be chosen for the A zeolite, which is at
least 90% exchanged with calcium beforehand. Prior to the adsorption, the zeolite
is adsorbent material is degassed at between 300°C and 450°C for a time of between 9
hours and 16 hours, under vacuum (P < 6.7x104Pa). Measurement of the adsorption
isotherms is then performed on a machine of ASAP 2020 type from Micromesitlcs, taking
at least 35 measurement points at relative pressures of ratio PJPO between 0.002 and 1.
The micropore volume is determined according to Dubinin and Raduskevitch from the
20 isotherm obtained, by applying standard IS0 15901-3 (2007). The micropore volume
evaluated according to the Dubinin and Raduskevitch equation is expressed in cm3 of
liquid adsorbate per gram of zeolite adsorbent material. The measurement uncertainty is +
0.003 cm3.g-', the measurements being carried out on the zeolite adsorbent material at
least 90% exchanged with calcium.
25
Volumetric micropore volume measurement:
[0102] The volumetric micropore volume is calculated from the micropore volume as
defined above and by multiplying said micropore volume by the apparent density of said
zeolite adsorbent material. The apparent density is measured as described in standard
30 DIN 894817.6.
Loss on ignition of the zeolite adsorbent materials:
[0103] The loss on ignition is determined under an oxidizing atmosphere, by calcination
of the sample in air at a temperature of 950°C + 25"C, as described in standard NF EN
35 196-2 (April 2006). The measurement standard deviaiion is less than 0.1%.
Qualitative and quantitative analysis by x-ray diffraction
[0104] The purity of the zeolites in the zeolite adsorbent materials is evaluated by x-ray
diffraction analysis, known to those skilled in the art by the acronym XRD. This
5 identification is carried out on a Bruker XRD apparatus.
[0105] This analysis makes it possible to identify the various zeolites present in the
adsorbent material since each of the zeolites has a unique diffractogram defined by the
positioning of the diffraction peaks and by their relative intensities.
[0106] The zeolite adsorbent materials are ground and then spread and levelled out on
ro a sample holder by simple mechanical compression.
[0107] The conditions under which the diffractogram is acquired on the Bruker D5000
machine are as follows:
* Cu tube used at 40 kV - 30 mA;
slit size (divergent, scattering and analysis) = 0.6 mm;
15 filter: Ni;
sample device rotating at: 15 rpm;
0 measuring range: 3" < 28 < 50";
increment: 0.02";
counting time per increment: 2 seconds.
20 [0108] Interpretation of the diffradogram obtained is performed with the EVA software
with identification of the zeolites using the ICDD PDF-2 release 201 1 base.
[0109] The amount of the LTA zeolite fractions, by weight, is measured by XRD
analysis; this method is also used to measure the amount of the zeolite fractions other
than LTA. This analysis is performed on a Bruker brand machine, and the amount by
2s weight of the zeolite fractions is then evaluated using the TOPAS software from the
company Bruker.
Measurement of the external surface area (m2/g) via the "t-plot" method:
[OllO] The "t-plot" calculation method exploits the adsorption isotherm data Q ads = f
30 (PIPO) and makes it possible to calculate the micropore surface area. The external
surface area may be deduced therefrom by determining the difference with the BET
surface area which calculates the total pore surface area in m2/g (S BET = micropore
surface area + external surface area).
[Olll] To calculate the micropore surface area via the t-plot method, the curve Q ads
3s (cm3.g-') is plotted as a function of t = thickness of the layer depending on the partral
pressure PIP0 that would be formed on a reference non-porous material (t function of log
(PIPO): Harkins-Jura equation applied: [13.99/(0.034-log(PIP0))"0.5]. In the interval t
between 0.35 nm and 0.5 nm, a straight line may be plotted which defines an adsorbed
intercept point Q, which makes it possible to calculate the micropore surface area. If the
5 material is not microporous, the straight line passes through 0, the measurements being
carried out on the zeolite adsorbent material at least 90% exchanged with calcium.
Mesopore volume measurement:
[0112] The measurement of the mesopore volume is estimated by conventional
10 methods such as the Barret-Joyner-Halenda volume measurements (adsorption of liquid
nitrogen at 77 K).
[0113] The mesopore volume is determined from the gas, such as nitrogen, adsorption
isotherm measurement, at its liquefaction temperature, as a function of the pore openings
of the zeolite: nitrogen will be chosen for the A zeolite, which is at least 90% exchanged
1s with calcium beforehand. Prior to the adsorption, the zeolite adsorbent material is
degassed at between 300°C and 450°C for a time of between 9 hours and 16 hours,
under vacuum (P <6.7x104 Pa). Measurement of the adsorption isotherms is then
performed on a machine of ASAP 2020 type from Micromeriiics, taking at least 35
measurement points at relative pressures of ratio PIP0 between 0.002 and 1. The
20 mesopore volume is determined according to Barret-Joyner-Halenda from the isotherm
obtained, by applying standard IS0 15901-2 (2007). The mesopore volume evaluated
according to the Barret-Joyner-Halenda equation is expressed in cm3 of liquid adsorbate
per gram of zeolite adsorbent material, the measurements being carried out on the zeolite
adsorbent material at least 90% exchanged with calcium.
25 [0114] The following examples serve to illustrate the present invention without aiming to
limit the scope thereof as defined by the appended claims.
Example I: Preparation of a zeolite adsorbent material according to the invention
Step: Synthesis of mesoporous A zeolite with addition of nucleating gel and
30 growth gel
a) Preparation of the growth gel
[01151 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
35 trihydrate (A1,o3.3H20, containing 65.2% by weight of A1203) 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.
[Of161 The stoichiometry of the growth gel is as follows: 3.13 Na2O/AI2O3/1.92S i02/68
H20. Homogenization of the growth gel is performed with stirring at 600 rpm for 15
5 minutes at 35°C.
b) Addition of the nucleating gel
[0117] 11.2 g of nucleating gel (iie. 1% by weight) of composition 2.05 Na,0/A1,03/1 .92
SiO2I87 H20 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
l o minutes of homogenization at 300 rpm, the stirring speed is reduced to 190 rpm and
stirring is continued for 30 minutes.
c) Ititroduction of the structuring agent into the reaction medium
[0118] 35.7 g of a solution of [3-(trimethoxysilyl)propyl]octadecyldimethylammonium
chloride (TPOAC) at 60% in methanol (MeOH) are introduced into the reaction medium
15 with a stirring speed of 600 rpm (TPOAC/AI,03 mole ratio = 0.04). A maturation step is
performed at 35°C for 10 minutes at 300 rpm before starting the crystallization.
d) Crysfalljzation
[0119] The stirring speed is lowered to 190 rprn 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
20 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) Filtrafion/washing
[0120] The solids are recovered on a sinter and then washed with deionized water to
25 neutral pH.
f) Drying
[01211 Drying is performed in an oven at 90°C for 8 hours to obtain a solid with a loss on
ignition of 20%.
30 w: Calcium exchange to obtain a mesoporous CaA zeolite powder
a) Calcium exchanges
I01221 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 cm3 of 0.5 M CaCI, solution at 70°C for 2 hours, and then
the mixture is filtered and washing is carried out with 280 cm3 of water. The operation is
repeated 3 times (triple exchange). A degree of calcium exchange of 92% is obtained.
b) Drying
[0123] 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
[0124] 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 . 7 ~ 1 P0a~).
[Of251 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 cm3.g-' and 92 m2.g-'. The number-average
diameter of the crystals is 0.8 pm. 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 SilAl mole ratio of the mesoporous CaA zeolite determined by X-ray fluorescence is
equal to 1.02.
Step: Preparation of mesoporous CaA zeolite agglomerates
[Of261 In the subsequent text, the weights given are expressed in anhydrous equivalent.
[Of2711 A homogeneous mixture consisting of 1700 g of mesoporous CaA zeolite crystals
obtained in step 2, of 300 g of ZeoclayB 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.
[0128] 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: Characterizations
[0129] The external surface area of the mesoporous CaA balls is equal to 92 rnZ.g-' of
adsorbent, the micropore volume is 0.202 cm3.g-' of adsorbent. The volumetric micropore
volume is 0.131 cm3 per cm3 of zeolite adsorbent material. The mesopore volume is equal
to 0.140 cm3.g-' of sodium-exchanged adsorbent. The total macropore and mesopore
volume, measured by mercury intrusion, is 0.41 cm3.g-' of adsorbent.
[01301 The SilAl atomic ratio of the adsorbent is 1.25. The SilAl ratio of the zeolite
s present in the adsorbent zeolite material, which is equal to 1.01, is determined by solid
silicon 29 NMR.
[0131] 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%.
10 Example 2: Comparative zeolite adsorbent material
[0132] SiliporiteB 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
rs of 92%.
[0133] The external surface area is equal to 39 m2.g-' of adsorbent, the micropore
volume is 0.238 cm3.g" of adsorbent. The volumetric micropore volume is 0.167 cm3 per
cm3 of zeoliie adsorbent material. The mesopore volume is equal to 0.07 cm3.g-' of
adsorbent. The total macropore and mesopore volume, measured by mercury intrusion, is
20 0.30 cm3.g-' of sodium-exchanged adsorbent.
[0134] The SiIAI 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%.
2s Example 3:
N/Oz separation tests on a axed bed of adsorbant with pressure swing adsorption
[01351 An N2102 separation test is carried out by adsorption in a single column according
to a principle presented in E. Alpay et al. (ibid.).
[0136] Figure 1 describes the assembly produced. A column (1) of internal diameter
30 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 zeoilte adsorbent material preferentially absorbs nitrogen, so that an oxygen-enriched
35 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
N~.min-'. 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
(1 I), for a period called the desorption time. The adsorption and desorption phases follow
5 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 1
/ Adsorption phase I Desorption phase
/ Valve (1 0) closed / Valve (1 0) open
Valve (4) open
Valve (5) closed
lo [013a 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.
[01381 The pressure at the inlet is fixed at 280 kPa relative. The outlet flow rate is fixed
at 1 NL.min-'. The adsorption time is fixed at 0.25 s. The desorption time is variable
15 between 0.25 s and 1.50 s. The oxygen concentration at outlet (9) is measured by means
of a Servomex 570A oxygen analyzer.
[Of391 Figure 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 I (according to the
20 invention) proves to be much more efficient than the solid of example 2 (comparative).
Valve (4) closed
Valve (5) open

CLAIMS
1. The use, for gas drying andlor separation, of at least one zeolite adsorbent
material comprising at least one A zeolite, said adsorbent having:
* an external surface area, measured by nitrogen adsorption and expressed in m2 per
gram of adsorbent greater than 20 m2.g-', and preferably between 20 m2.g-' and 300
m2.g-', and more preferably between 30 m2.g-' and 250 m2.g-' and even more
10 preferably between 40 m2.g-' and 200 m2.g-', and most particularly between 50 m2.g-'
and 200 m2.g-',
a non-zeolite phase (PNZ) content such that 0 < PNZ 5 30%, preferably 3% r PNZ 2
25%, more preferably 3% 5 PNZ 5 20%, advantageously 5% 5 PNZ 5 20%, even better
still 7% 5 PNZ 5 18%, measured by XRD (X-ray diffraction), by weight relative to the
IS total weight of the adsorbent,
a mesopore volume of between 0.07 cm3.g-' and 0.18 cm3.g-', preferably between
0.10 cm3.g-' and 0.18cna3.g", and more preferably between 0.12cm3.g-' and
0.18 cm3.g", more preferably between 0.14 cm3.g-' and 0.18 cm3.g-', limits included,
and an SilAl atomic ratio of the adsorbent of between 1.0 and 2.0, preferably between
20 1.0 and 1.6, and entirely preferably between 1.0 and 1.4,
all of the measurements being carried out on the adsorbent material at least 90%
exchanged with calcium.
2. The use as claimed in claim 1, wherein said at least one zeolite adsorbent
2s material has a (Vmicro - Vmeso)iVmicro ratio of between -0.5 and 1.0, limits not included,
preferably between -0.1 and 0.9, limits not included, preferably between 0 and 0.9, limits
not included, more preferably between 0.2 and 0.8, limits not included, more preferably
between 0.4 and 0.8, limits not included, preferably between 0.6 and 0.8, limits not
included, where Vmicro is the micropore volume measured by the Dubinin-Raduskevitch
30 method and Vmeso is the mesopore volume determined by the Barrett-Joyner-Halenda
(BJH) method, all of the measurements being carried out on the adsorbent material at
least 90% exchanged with calcium.
3. The use as claimed in claim 1 or claim 2, in which said at least one zeolite
35 adsorbent material has a micropore volume (Dubinin-Raduskevitch volume), expressed in
cm3 per gram of zeolite adsorbent material, of between 0.160 cm3.g-' and 0.280 ~ m ~ . ~ . ' ,
preferably between 0.180 cm3.g-' and 0.280 cm3.g-', preferably between 0.200 cm3.g-' and
0.280 cm3.g-', more preferably 0.220 cm3.g-' and 0.280 cm3.g-', measured on the
adsorbent material at least 90% exchanged with calcium.
5
4. The use as claimed in any one of claims 1 to 3, wherein said at least one A
zeolite has an SiIAI ratio equal to 1.00 +I- 0.05, said SiIAI ratio being measured by solid
silicon 29 Nuclear Magnetic Resonance (NMR).
l o 5. The use as claimed in any one of claims 1 to 4, said zeolite adsorbent material
comprising at least one cation chosen from the ions of groups IA, IIA, IIIA, IB, llB and lllB
of the periodic table, the trivalent ions of the lanthanide or rare earth series, the zinc(ll)
ion, the silver(1) ion, the cupric (11) ion, the chromium(lll) ion, the ferric (Ill) ion, the
ammonium ion andlor the hydronium ion, the preferred ions being calcium, lithium,
15 sodium, potassium, barium, cesium, strontium, zinc and rare-earth ions and more
preferably sodium, calcium and potassium ions, and mixtures thereof.
6. The use as claimed in any one of claims 1 to 5, for drying cracked gases.
20 7. The use as claimed in claim 6, wherein the zeolite adsorbent material comprises
at least one 3A zeolite, which is preferably mesoporous.
8. The use as claimed in any one of claims 1 to 5, for drylng andlor separating
refrigerant flu~ds, preferably HFCs and HFOs, and preferably drylng I,l,l,2-tetrafluoro-
2s ethane and 2,3,3,3-tetrafluoropropene.
9. The use as claimed in claim 8, wherein the zeolite adsorbent material comprises
at least one A zeolite, which is preferably mesoporous, chosen from 3A, 4A and 5A
zeolites, and mixtures thereof.
30
10. The use as claimed in any one of claims 1 to 5, for drying alcohols, in particular
ethanol.
11. Tine use as claimed in cla~m1 0, wherein the zeolite adsorbent material comprises
35 at least one 3A zeolite, which is preferably mesoporous.
12. The use as claimed in any one of claims 1 to 5, for drying andlor separating air
and industrial gases.
5 13. The use as claimed in claim 12, wherein the zeolite adsorbent material comprises
at least one A zeolite, which is preferably mesoporous, chosen from 3A, 4A and 5A
zeolites. and mixtures thereof.
14. The use as claimed in any one of claims 1 to 5, for purifying olefins, in particular
lo for removing impurities, preferably for removing oxygen-bearing impurities, and more
preferably for removing methanol.
15. The use as claimed in claim 14, wherein the zeolite adsorbent material comprises
at least one A zeolite, which is preferably mesoporous, chosen from 3A, 4A and 5A
is zeolites, and mixtures thereof, preferably from 3A and 4A zeolites, and mixtures thereof.
16. The use as claimed in any one of dairns 1 to 5, for drying andlor purifying natural
gas, in particular for removing impurit~es and preferably for removing ca&on dioxide,
hydrogen sulf~dea ndlor light mercaptans
20
17. The use as claimed in claim 16, wherein the zeolite adsorbent material comprises
at least one A zeol~te, which is preferably mesoporous, chosen from 3A, 4A and 5A
zeolites, and mixtures thereof
2s 18. The use as claimed in any one of claims 1 to 5, for separating paraffins.
19. The use as claimed in claim 18, wherein the zeolite adsorbent material comprises
at least one 5A zeolite, which is preferably mesoporous.
30 20. The use as claimed in any one of claims 1 to 5, for drying andlor purifying
syngases, in particular for producing hydrogen.
21. The use as claimed in claim 20, wherein the zeolite adsorbent material comprises
at least one A zeolite, which is preferably mesoporous, chosen from 3A, 4A and 5A
35 zeolites, and mixtures thereof.
22. A zeolite adsorbent material which has:
an SiIAI ratio of said adsorbent, such that 1.0 5 SiIAI < 2.0, preferably 1.0 5 SiIAI 5 1.6,
more preferably 1 r SiIAI 5 1.4,
5 a mesopore volume of between 0.07 cm3.g-' and 0.18 cm3.g-', preferably between
0.10 cm3.g-' and 0.18 cm3.g-', and more preferably between 0.12 cm3.g-' and
0.18 cm3.g-', more preferably between 0.14 cm3.g-' and 0.18 cm3.g-', limits included,
a ratio (Vmicro - Vmeso)Nmicro between -0.3 and 1 .O, limits not included, preferably
-0.1 and 0.9, limits not included, preferably 0 and 0.9, limits not included, more
10 preferably between 0.2 and 0.8, limits not included, more preferably between 0.4 and
0.8, limits not included, preferably between 0.6 and 0.8, 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 < PNZ 5 30%, preferably 3% 5 PNZ r
IS 25%, more preferably 3% 5 PNZ 2 20%, advantageously 5% 5 PNZ 5 20%, even better
still 7% r PNZ 5 18%, measured by XRD, by weight relative to the total weight of the
zeolite adsohent material,
all of the measurements being carried out on the zeolite adsorbent material at least 90%
exchanged with calcium.
20
23. The zeolite adsorbent material as claimed in claim 22, which has a micropore
volume (Dubinin-Raduskevitch volume), expressed in cm3 per gram of zeolite adsorbent
material, of between 0.160 cm3.g-' and 0.280 cm3.g-', preferably between 0.180 cm3.g-'
and 0.280 cm3.g-', more preferably between 0.200cm3.g-' and 0.280cm3.g-',
2s advantageously between 0.220 cm3.g-' and 0.280 cm3.g-', said micropore volume being
measured on the zeolite adsorbent material at least 90% exchanged with calcium.
24. The zeolite adsorbent material as claimed in either one of claims 22 and 23, of
which the total volume of the macropores and mesopores, measured by mercury
30 intrusion, is between 0.15 cm3.g-' and 0.50 cm3.g-', preferably between 0.20 cm3.g-' and
0.40 cm3.g-' and very preferably between 0.20 cm3.g-' and 0.35 cm3.g-', measured on the
zeolite adsorbent material at least 90% exchanged with calcium.
25. The zeolite adsorbent material as claimed in any one of claims 22 to 24, which
3s has an external surface area, measured by nitrogen adsorption and expressed in mZ per
. .
'>
I
.. i l
2 -1 ' . gram of adsorbent, 'greater tha; 20. m .g !, and preferably between 20 m2.g? and 300 . . :
m2.g-', and more 'preferably between 30 d.ga-ndi 250 m".g" and more pr