U.S. patent application number 16/214886 was filed with the patent office on 2019-04-11 for process for limiting self-heating of activated catalysts.
The applicant listed for this patent is Eurecat S.A.. Invention is credited to Mathieu Baffert, Pierre Dufresne, Pauline Galliou, Sharath Kirumakki.
Application Number | 20190105649 16/214886 |
Document ID | / |
Family ID | 51417501 |
Filed Date | 2019-04-11 |
United States Patent
Application |
20190105649 |
Kind Code |
A1 |
Dufresne; Pierre ; et
al. |
April 11, 2019 |
Process for Limiting Self-Heating of Activated Catalysts
Abstract
The invention provides a process for limiting self-heating of
activated particle catalysts wherein the catalyst particles are
placed in motion inside a hot gas flow that passes through them and
a liquid composition containing one or several film forming
polymer(s) is pulverized onto the particles in motion until a
protective layer is obtained on the surface of said particles
containing said film forming polymer and having an average
thickness of less than or equal to 20 .mu.m. The invention also
provides the use of this process to reduce the quantities of toxic
gases that may be emitted by the activated catalysts, as well as an
activated catalyst for the hydroconversion of hydrocarbons covered
with a continuous protective layer that are obtained by this
process.
Inventors: |
Dufresne; Pierre; (Aouste
Sur Sye, FR) ; Galliou; Pauline; (Saint Laurent Du
Pape, FR) ; Baffert; Mathieu; (Guilherand Granges,
FR) ; Kirumakki; Sharath; (Friendswood, TX) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Eurecat S.A. |
La Voulte-Sur-Rhone |
|
FR |
|
|
Family ID: |
51417501 |
Appl. No.: |
16/214886 |
Filed: |
December 10, 2018 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
14790262 |
Jul 2, 2015 |
10195601 |
|
|
16214886 |
|
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|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B01J 23/002 20130101;
C10G 45/04 20130101; B01J 31/34 20130101; B01J 31/06 20130101; B01J
37/0232 20130101; B01J 37/0219 20130101; B01J 23/882 20130101; B01J
23/883 20130101; B01J 23/8885 20130101; B01J 35/0006 20130101; B01J
37/0221 20130101; B01J 2523/00 20130101; B01J 33/00 20130101 |
International
Class: |
B01J 33/00 20060101
B01J033/00; C10G 45/04 20060101 C10G045/04; B01J 31/06 20060101
B01J031/06; B01J 31/34 20060101 B01J031/34; B01J 23/888 20060101
B01J023/888; B01J 23/883 20060101 B01J023/883; B01J 35/00 20060101
B01J035/00; B01J 37/02 20060101 B01J037/02; B01J 23/882 20060101
B01J023/882; B01J 23/00 20060101 B01J023/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 3, 2014 |
FR |
1456359 |
Claims
1. A process for limiting self-heating of activated catalyst
particles, comprising: placing activated catalyst particles in
motion in a fluidized bed within a hot gas flow passing
continuously through the activated catalyst particles, wherein the
gas has a temperature greater than 25.degree. C.; and spraying onto
the activated catalyst particles in motion a liquid composition
comprising a solution or a dispersion of one or more film forming
polymer(s) in a solvent, wherein the liquid composition contains
0.5% to 50% by weight of film-forming polymer(s) with respect to
the total weight of the composition, wherein, upon evaporation of
the solvent from the liquid composition, a protective layer
containing said film-forming polymer(s) is formed on the surface of
the activated catalyst particles, and wherein the protective layer
has an average thickness lower than or equal to 20 .mu.m; thereby
limiting self-heating of the activated catalyst particles.
2. The process according to claim 1, wherein the liquid composition
contains from 0.5 to 25% by weight, with respect to the total
weight of the composition.
3. (canceled)
4. (canceled)
5. The process according to claim 1, wherein the hot gas has a
temperature ranging from 30 to 150.degree. C.
6. The process according to claim 1, wherein the gas flows at a
rate ranging from 5 to 100 m.sup.3 per hour per kilogram of
catalyst.
7. The process according to claim 1, wherein the one or more
film-forming polymer(s) forming the protective layer comprises from
50 to 100% by weight of the protective layer.
8. The process according to claim 1, wherein the one or more
film-forming polymer(s) is (are) selected from the group consisting
of: vinyl alcohol homo- and copolymer; polyvinyl alcohols and
copolymers made up of vinyl alcohol and olefin(s) monomers ethylene
and vinyl alcohol monomers (EVOH copolymers)-; partially hydrolyzed
vinyl alcohol homo- and copolymers containing non-hydrolyzed vinyl
acetate units-; polyethylene glycols-; collagen; polyethylene
terephtalates (PET)-; polyethylene naphtalates (PEN)-; polyamides;
polysaccharides; polyvinyl chlorides (PVC)-; polyvinylidene
chlorides (PVDC)-; polyacrylonitriles (PAN)-; polyacrylate resins;
copolymers of which at least one of the monomers is of the acrylate
type; and mixtures thereof.
9. The process according to claim 1, wherein the film forming
polymer is selected from the group consisting of polyvinyl
alcohols, copolymers made up of vinyl alcohol and olefin(s)
monomers.
10. The process according to claim 1, wherein the average thickness
of the protective layer is less than or equal to 10 .mu.m.
11. The process according to claim 1, wherein the total amount of
film-forming polymer used is within a range between 0.1 to 6% by
weight with respect to the total weight of the initial activated
catalyst particles.
12. The process according to claim 1, wherein the process further
results in reducing emission of toxic gases by the activated
catalyst particles.
13. An activated hydrocarbon hydroconversion catalyst obtained by a
process as defined in claim 1, comprising activated catalyst
particles which are each covered on their surface by a continuous
protective layer having an average thickness ranging from 0.1 to 20
.mu.m and comprising from 50 to 100% by weight of one or several
film forming polymer(s) chosen among: vinyl alcohol homo- and
copolymers; partially hydrolyzed vinyl alcohol homo- and
copolymers; polyethylene glycols-; collagen-; polyethylene
terephtalates (PET)-; polyethylene naphtalates (PEN)-; polyamides-;
polysaccharides; polyvinyl chlorides (PVC)-; polyvinylidene
chlorides (PVDC)-; polyacrylonitriles (PAN)-; polyacrylates
resins-; copolymers of which at least one of the monomers is of the
acrylate type-; and mixtures thereof; wherein the total amount of
film forming polymer represents from 0.1 to 0.4% by weight with
respect to the total weight of the initial catalyst.
14-18. (canceled)
19. The process according to claim 1, wherein the liquid
composition contains from 1 to 10% by weight of film forming
polymer, with respect to the total weight of the composition.
20. The process according to claim 1, wherein the hot gas has a
temperature ranging from 50 to 100.degree. C.
Description
[0001] This application is a continuation of U.S. Ser. No.
14/790,262, filed Jul. 2, 2015, which claims priority to French
Application No. 1456359, filed on Jul. 3, 2014, the entire contents
of which applications are incorporated herein by reference.
[0002] This invention concerns a process for limiting self-heating
of activated catalysts, such as during their storage, handling and
transportation.
[0003] According to the invention, the process also permits
limiting toxic gases that may be released by these catalysts.
[0004] The purpose of this invention is also a coated activated
hydroconversion catalyst, obtained by the process described
above.
[0005] Catalysts that can be treated by the process according to
the invention are for instance, without being limited thereto,
those used in the hydrocarbon treatment processes, in particular in
the areas of oil refining and petrochemistry, and more in
particular, in the hydroconversion processes of hydrocarbons.
[0006] The hydrocarbon treatment processes conducted in refineries
and/or petrochemical units include a certain number of treatments
possibly made in the presence of hydrogen which are aimed at
modifying the structure of the hydrocarbon molecules and/or to
eliminate hydrocarbonated cuts from undesirable compounds such as
sulfur, nitrogen, aromatic and metal compounds. As non-limiting
examples can be mentioned, hydrocracking or hydroconversion,
reforming, isomerizing, alkylation, hydrogenation, dehydrogenation
processes and the so-called hydrotreatment processes such as
hydrodesulfurization, hydrodenitrogenation, hydrodearomatization,
hydrodemetalization, hydrodeoxygenation processes.
[0007] Most of these hydrocarbon treatment processes call upon
solid particle catalysts also called "catalyst grains". These
catalyst particles include a porous support made of a one or two
refractory inorganic oxide base onto which one or several
catalytically active metals are deposited. These metals include
most often one or more metals of group VIII of the periodic
classification of elements, and/or one or several metals of group
VIB.
[0008] Kinetics of the hydrocarbon treatment reactions is among
other limited by the diffusion speed of the hydrocarbon molecules
(often considerable in size) towards the catalytic sites located in
the catalyst pores. That is why the manufacturers attempt to
prepare the catalysts with a specific surface and a porosity that
is as great as possible, which leads to small sized particle
catalysts.
[0009] At the end of manufacturing the catalyst, or at the end of
its regeneration in the case of a previously ready used catalyst,
the active metals turn into metal oxides which are not active as
such.
[0010] To enable the catalysts to be active for the various
hydrocarbon treatment processes, activation of the catalyst is
required, in other words, a treatment of the catalyst in order to
transform the metal oxides into active metal species.
[0011] Consequently, in the case of hydrocarbon hydrotreatment
catalysts, activation takes place in general by sulfuration of the
catalyst, which consists of performing a treatment of the latter by
means of sulfur compounds for the purpose of transforming at least
partially, the metal oxides into mixed sulfurs which form the
active phase of the catalyst.
[0012] This activation stage is particularly important because it
conditions the activity of the catalyst during its subsequent
use.
[0013] This activation of the catalysts can be done in situ (in
other words, directly in the reactor where the catalyst is used,
before its startup) or ex situ (in other words, outside the
reactor).
[0014] In order to optimize the yield of the units, and in
particular, to diminish their shutdown time during catalyst renewal
operations in the reactors when the latter is used up, more and
more, the catalyst activation treatments are performed ex situ.
[0015] As such, catalysts are activated in special treatment units
that use sulfur compounds, then, may be stored for more or less
long periods of time which may last sometimes up to a couple of
months, before being transported to the reactor in which they will
be loaded.
[0016] However, activated catalysts have the drawback of being
particularly unstable chemically. Activated metal sites are
especially sensitive, and they react in contact with air for
instance. In the case of sulfur catalysts, metal sulfides present
at the surface of the catalyst particles are reactive, and cause
exothermic oxidation reactions that may lead to the formation of
SO.sub.2, which is a toxic gas.
[0017] This formation of SO.sub.2 is a phenomenon that represents a
risk for personnel present during loading. For instance, this gas
may form in the reactor, as soon as a small part of the catalyst
bed undergoes self-heating. However, the tolerable exposure limit
threshold over a short period of time is very low (5 ppm).
[0018] Activated catalysts are also known to result in self-heating
phenomena, and particularly stringent precautions must be taken
during storage, transportation and handling.
[0019] The self-heating properties of a material can be
characterized by an international test, described by UN (test
described in the "Recommendation on the transport of dangerous
goods. Manual for Tests and Criteria", ISSN 1014-7160, Section
33.3) document. This test describes a procedure for measuring the
degree of self-heating of a sample, conducted in a 1 L box at
different temperatures (100, 120 or 140.degree. C.) to define the
category in which the material will be placed. In certain cases, a
procedure using a small box of 15 mL may also be used.
[0020] To prevent any risk, self-heating catalysts must be kept in
an inert atmosphere, for instance, using nitrogen. Loading
operations of activated catalysts in the reactors take place
generally with nitrogen which complicates these operations
considerably and generates considerable additional expenses.
[0021] In addition, in spite of these precautions, storage,
transportation and handling of activated catalysts remain
particularly dangerous by reason of their self-heating nature, and
the risk to personnel and equipment coming into contact with these
catalysts remains considerable.
[0022] Consequently, there is a need to find new solutions that
permit on the one hand to reduce as much as possible the risks
associated with using these activated catalysts, and on the other
hand of doing away with the need to keep them in an inert
atmosphere, while limiting to a high degree the potential toxic gas
emissions.
[0023] For that purpose, a certain number of solutions have been
proposed in the prior state of the art.
[0024] For instance, it has been proposed in the
U.S. Pat. Nos. 5,681,787 and 3,453,217 to fill more or less fully
the porosity of the catalyst particles, with compounds aimed at
protecting actives sites, most often hydrocarbons.
[0025] However, the solutions proposed in the prior state of the
art, are not fully adequate.
[0026] In particular, they do not always permit to diminish
sufficiently the self-heating nature of the activated catalysts,
with respect to the particularly strict codes nowadays. In
addition, these solutions do not provide a significant reduction of
the harmful gas emissions.
[0027] Often, to effectively protect the catalyst, they require
laying a relatively thick layer of protective material, which
consequently reduces the density of the catalyst load in the
reactor, and thus reduces the yield of the latter. Indeed, the
place occupied by this layer significantly increases the actual
diameter of the grain, and consequently of the volume occupied by
each grain. The volume of the reactor to be loaded which is
necessarily limited, is consequently, in the case of a coated
catalyst, partially occupied by the protective substance, and this
is all the more the case with an increased thickness of the
catalyst layer. The performances of a catalyst bed are proportional
to the quantity of active catalytic substance, consequently they
may be significantly diminished if the coating layer is too thick,
which cannot be tolerated. In addition, during the elimination of
the protective material layer, the volume occupied by the latter is
freed up. If this occupied volume is considerable, the catalyst bed
will be modified, which may generate preferential ways to the
feedstock circulating through the bed, which is contrary to the
requirements of a perfect distribution of the feedstock throughout
the catalyst bed in the reactor, and becomes particularly harmful
for the performance ratings of the unit.
[0028] This invention aims at proposing a method that permits on
the one hand to limit efficiently the self-heating phenomena of the
activated catalysts, and on the other hand, to eliminate the
drawbacks of the methods of the prior state of the art.
[0029] The Applicant has found out unexpectedly that this goal was
met with a process in which the activated catalyst particles are
covered with a very thin protective layer of film forming polymer
using a particular process in which the particles are kept moving
within a hot gas flow while a liquid composition containing the
film forming polymer is pulverized over said particles.
[0030] Preferably, the pulverization takes place using an
atomization nozzle in which the liquid composition is mixed with a
gas under pressure, preferably compressed air, which permits
obtaining very fine drops.
[0031] The purpose of the process according to the invention is to
create a continuous layer of a protective material on the external
surface of the catalyst grains. The basic principle that consists
in protecting a catalyst by a protective material has already been
described in the prior state of the art, but obtaining a catalyst
that meets the requirements described above is very complex. The
Applicant has discovered that in order to meet all these
requirements efficiently, particular film forming polymer based
protective materials should be associated with a high precision
coating process.
[0032] Consequently, the purpose of this invention is a process to
limit the self-heating of activated particle catalysts, in which
catalyst particles are placed in motion within a hot gas flow that
passes through them, and a liquid composition containing one or
several film forming polymer(s) is pulverized over the moving
particles, until on the surface of said particles, a protective
layer containing said film forming polymer and having an average
thickness that is lower than or equal to 20 .mu.m is obtained.
[0033] According to this invention, the process permits to
remediate the drawbacks of the processes described in the prior
state of the art.
[0034] Activated catalysts traited with the process of the
invention see their self-heating properties diminished to a large
extent.
[0035] In addition, the Applicant has observed that surprisingly,
the process according to the invention permits to reduce the toxic
gas emissions in a particularly effective way.
[0036] Catalysts treated with the invention process can thus be
stored or transported in large quantities, for instance in bags or
containers of considerable volume, and be handled (for instance,
loaded into the reactors) without special precautions.
[0037] In addition, the Applicant has observed that the process
according to the invention permitted to preserve a good efficiency
of the units into which the activated catalyst is loaded, without
any substantial loss of activity resulting from loading catalyst
grains coated with a protective layer.
[0038] Finally, implementation of such a protection does not affect
the activated catalyst activity, which once it does not have the
protective coating anymore, keeps its full activity.
[0039] In accordance with the invention, the catalyst particles are
covered with a protective layer comprising one or more film forming
polymer(s).
[0040] By "polymer" is understood in the sense of the invention,
compounds that include at least two repeated units, preferably at
least three repeated units and more especially, at least ten
repeated units.
[0041] By "film forming polymer" is meant, as already known by
itself, a polymer capable of forming by itself or in the presence
of an auxiliary film-forming agent, a macroscopically continuous
film on a support, such as on inorganic oxide base materials such
as alumina for instance.
[0042] The protective layer or coating according to the invention
can include one or several film forming polymer(s) mixed with one
or several other compound(s) which can be polymeric or
non-polymeric. The other compounds that may be present in the
protective layer according to the invention, are then introduced in
a mixture with the film forming polymer(s), in the liquid
composition that is pulverized on the moving particles.
[0043] The protective layer may also consist in full of one or
several film forming polymers.
[0044] Preferably, the protective layer according to the invention
contains from 50 to 100% by weight one or several film forming
polymers. Especially preferred, the protective layer according to
the invention is fully made up of one or several film forming
polymers.
[0045] Preferably, the film forming polymer(s) used in this
invention are selected from among: [0046] vinyl alcohol homo- and
copolymers, such as polyvinyl alcohols and copolymers made of vinyl
alcohol and olefin(s) monomers such as copolymers made of ethylene
and vinyl alcohol monomers (EVOH copolymers); [0047] partially
hydrolyzed vinyl alcohol homo- and copolymers, in other words,
still containing non-hydrolyzed vinyl acetate units; [0048]
polyethylene glycols; [0049] collagen; [0050] polyethylene
terephtalates (PET); [0051] polyethylene naphtalates (PEN); [0052]
polyamides; [0053] polysaccharides, in particular cellulose
polymers and their derivatives (among which, C.sub.1-C.sub.4 alkyl
celluloses are preferred and even more in particular, methyl
celluloses) and possibly modified starches; [0054] polyvinyl
chlorides (PVC); [0055] polyvinylidene chlorides (PVDC); [0056]
polyacrylonitrils (PAN); [0057] polyacrylate resins, such as in
particular methyl polyacrylates; [0058] copolymers of which at
least one of the monomers is of the acrylate type; [0059] and their
mixtures.
[0060] Polyvinyl alcohols and the copolymers made with vinyl
alcohol and olefins monomers are especially preferred. Among the
latter are preferred especially the copolymers made of vinyl
alcohol and ethylene monomers also called EVOH copolymers.
[0061] According to the invention, pulverization of the liquid
composition containing the film forming polymer(s) is continued
until, on the surface of the particles, a protective layer is
obtained with a defined average thickness (in any event, less than
or equal to 20 .mu.m), which means that when the protective layer
with the desired thickness as defined below is obtained, this
pulverization is stopped.
[0062] The average thickness of the protective layer according to
the invention is less than or equal to 20 .mu.m, and preferably
less than or equal to 10 .mu.m.
[0063] More preferred is that the average thickness of the
protective layer ranges from 0.1 to 10 .mu.m, even more preferred
from 0.2 to 10 .mu.m, and even better from 0.5 to 8 .mu.m.
[0064] The average thickness of the layer or coating covering the
catalyst particles may be determined by scanning electron
microscopy.
[0065] According to this invention, the quantity of film forming
polymer used must be adequate to permit covering the catalyst
particles as completely as possible, while making sure that the
protective layer remains as thin as possible.
[0066] For that purpose, the total quantity of film forming polymer
used ranges advantageously from 0.1 to 6% by weight, preferably
from 0.5 to 4% by weight, and even more preferred from 1 to 3% by
weight, with respect to the total weight of the initial
catalyst.
[0067] By total weight of the initial catalyst, one designates here
the weight of the unprotected activated catalyst, in other words
before covering with the protective layer according to the
invention.
[0068] The film forming polymer(s) as well as the other compounds
that may be present in the protective layer according to the
invention are deposited on the catalyst by pulverizing a liquid
composition that contains them.
[0069] According to a first embodiment, the liquid composition
pulverized on the catalyst particles contains a solvent chosen
among water, an organic solvent or a mixture of water and organic
solvent, as well as the film forming polymer(s), dissolved or
dispersed in said solvent. It may also contain, as applicable, one
or several stabilizing agents.
[0070] In this case, where the liquid composition is a solution or
a dispersion of film forming polymer in a solvent, said composition
contains advantageously from 0.1 to 50% by weight of film forming
polymer, and preferably from 0.5 to 25% by weight, and even more
preferably from 1 to 10% by weight of film forming polymer, with
respect to the total weight of the composition.
[0071] In the case of a dispersion of the film forming polymer(s)
in a solvent, the size of the particles of dispersed polymer is
advantageously less than or equal to 500 nm and preferably less
than or equal to 200 nm.
[0072] According to a second embodiment, the liquid composition
pulverized over the catalyst particles contains the film forming
polymer(s) in the molten state. In particular, the liquid
composition pulverized over the catalyst particles may be fully
made up by the film forming polymer(s) in the molten state.
[0073] According to the invention, the catalyst particles are
placed in motion within a hot gas flow passing through them, in
other words, within a gas flow that passes through the mass of
moving particles.
[0074] Any device that permits to achieve this objective can be
employed for this invention.
[0075] According to a first variant, the process according to the
invention can be implemented in a perforated drum in which the
catalyst particles are put in motion, and the hot gas flow runs
continuously through it.
[0076] According to a second variant, the process according to the
invention can be implemented by placing the catalyst particles in a
fluidized bed by means of the hot gas flow. In this variant, the
process according to the invention can be performed in batch or
continuously.
[0077] The hot gas flow passing through the catalyst particles in
motion may consist of any gas or gas mixture. Preferably, it is an
air flow.
[0078] By "hot" gas flow is understood a gas flow for which the
temperature is higher than the ambient temperature, in other words,
higher than 25.degree. C.
[0079] Advantageously, the gas flow passing through the catalyst
particles has a temperature ranging from 30 to 150.degree. C., and
preferably from 50 to 100.degree. C.
[0080] The gas flow rate ranges advantageously from 5 to 100
m.sup.3 per hour and per kilogram of catalyst.
[0081] The composition containing the film forming polymer(s) is
pulverized into fine droplets, preferably continuously, onto the
catalyst particles in motion.
[0082] Preferably, pulverization takes place by atomization, in
other words by pulverizing the liquid composition mixed with a gas
under pressure, preferably compressed air.
[0083] In general, the liquid composition is advantageously
pulverized at a temperature ranging from 25 to 200.degree. C.
[0084] In the event that the liquid composition contains the film
forming polymer(s) in a dissolved or dispersed state in a solvent,
said composition is preferably pulverized at a temperature ranging
from 25 to 100.degree. C.
[0085] In the event that the liquid composition contains the film
forming polymer(s) in a molten state, said composition is
preferably pulverized at a temperature ranging from 50 to
150.degree. C.
[0086] In the event that the process according to the invention is
performed in a perforated drum, pulverization takes place
preferably on the top surface of the catalyst bed.
[0087] In the event that the process according to the invention is
achieved by placing the catalyst particles in a fluidized bed,
pulverization may take place either on the top surface of the
catalyst bed, or directly inside the bed.
[0088] The processes described above permit the creation of a
continuous protective layer on the external surface of the grains,
which guarantees a maximum efficiency of the process according to
the invention.
[0089] After covering the catalyst grains with a protective layer
according to the invention, said grains can be dried if necessary,
for instance in open air or in the presence of a gaseous air flow
or of any other appropriate gas.
[0090] The process according to this invention may be applied to
any solid activated catalyst that is under the form of particles,
such as those used for the treatment of hydrocarbon feedstocks such
as in the areas of oil refining or of petrochemistry.
[0091] By "activated catalyst" one designates in this invention
catalysts containing active sites that may react spontaneously, for
instance when in contact with air and/or humidity.
[0092] Active sites may be in particular metal sulfurs in the case
of hydrotreatment catalysts.
[0093] The process according to the invention applies in particular
to the protection of activated catalysts for hydrocarbons
hydroconversion. These catalysts are under the form of particles
that include a refractory oxide support on which is deposited at
least a metal sulfur chosen among the metals of group VIII and the
metals of group VIB of the Periodic Classification of Elements.
[0094] Preferably, the catalysts contain at least a metal of group
VIII of the periodic classification of elements, such as for
instance cobalt, nickel, iron, palladium, platinum. These metals
may be associated with at least one metal of group VIB such as for
instance molybdenum, tungsten, chrome. The content in metal or
metals of group VIII falls generally between 0.1 and 20% by weight
with respect to the total weight of the unprotected catalyst,
sometimes up to 50%. The content in metal or metals of group VIB
falls generally between 3 and 30% by weight with respect to the
total weight of the catalyst (unprotected).
[0095] Preferably, the catalyst support is chosen among aluminas,
silicas, amorphous or crystalized silica-aluminas (zeoliths). More
preferably, the support contains at least 30% by weight, and even
better at least 50% by weight, of alumina.
[0096] The process according to the invention is particular
appropriate for treating catalysts containing one of the following
metal associations: CoMo, NiMo, NiW, NiCoMo, deposited on an
alumina based support.
[0097] These catalysts may contain one or several additives such as
organic additives, halogen, boron, phosphorus compounds.
[0098] The catalysts targeted by the invention take on the form of
particles of variable shapes, preferably spheric, cylindrical, or
multilobe shapes and for which the maximum average dimension in
number does not exceed 5 mm in general.
[0099] For catalyst particles which are cylindrical or multilobe in
shape, the average diameter in number ranges generally from 0.8 to
4 mm and the average length in number ranges generally from 2.5 to
5 mm. In certain applications, spherical shaped grains are used,
for which the average diameter in number varies generally from 1.5
to 5 mm.
[0100] The average dimensions in number of the catalyst grains may
be determined, as is already known, by video grain size or by using
a slide gauge. Typically, one may use the CAMSIZER video grain
sizer, developed by the RETSCH company.
[0101] These catalysts may have a specific surface measured by the
BET method, generally falling between 100 and 300 m.sup.2/g, a
porous volume determined by nitrogen absorption, ranging from 0.20
to 1 ml/g, and an average pores diameter determined by the nitrogen
absorption ranging from 7 to 20 nm.
[0102] The process according to this invention applies to new
catalysts on which an activation treatment has been done, in other
words, catalysts that have never been used, as well as to activated
regenerated catalysts, in other words, used catalysts which have
been regenerated in order to remove their hydrocarbon residue
(coke) and to restore a level of activity enabling their reuse and
which have subsequently being activated during a successive
stage.
[0103] It must be pointed out that even if in this specification
the process according to the invention is described with respect to
specific catalysts used in hydrocarbon treatment processes, it may
be implemented to protect any solid particle catalyst, having at
its surface active sites which are particularly fragile and/or
reactive and/or susceptible of producing toxic gases.
[0104] Deprotection of the catalyst particles takes place
preferably once they have been loaded in the reactor in which they
are being used.
[0105] It is done by placing the catalyst under conditions in which
the material layer present at the surface of the particles, is
eliminated.
[0106] In an especially preferred way, the film forming polymer(s)
used in this invention is/are chosen so that it/they are eliminated
spontaneously when coming in contact with the feedstock during
startup of the reactor in which the catalyst is used. This
embodiment enables to remove very simply and economically, the
protective layer covering the catalyst at the time of starting up
the reactor.
[0107] The film forming polymer(s) are thus preferably chosen among
polymers that decompose or which are washed by the feedstock at
temperatures between ambient temperature and the operating
temperature of the reactor, in other words, at a temperature
between 25.degree. C. and 400.degree. C., and at a pressure between
atmospheric pressure and 20 MPa.
[0108] In a more preferred way, the film forming polymer(s) are
chosen among the compounds that decompose or are washed by the
feedstock at a temperature ranging from 50.degree. C. to
400.degree. C., preferably from 100 to 300.degree. C. and at a
pressure ranging from 0.1 to 10 MPa.
[0109] By feedstock is meant, in the case of hydrocarbon treatment
catalysts, the hydrocarbon cuts having typically a boiling range at
atmospheric pressure falling within a range of 75 to 650.degree. C.
and that may be put in contact with the catalyst in the liquid or
gaseous state.
[0110] The purpose of this invention is also the use of the process
as described above, to reduce the quantities of toxic gases that
may be emitted by the activated catalysts.
[0111] Finally, the purpose of this invention is an activated
hydroconversion catalyst of hydrocarbons in the form of particles
covered with a continuous protective layer, that may be obtained by
the process described above.
[0112] This catalyst is made up of activated catalytic particles
(in other words, comprising active sites) and which are each
covered at their surface by a continuous protective layer having an
average thickness of 0.1 to 20 .mu.m, and comprising from 50 to
100% by weight one or several film forming polymer(s) selected
among: [0113] vinyl alcohol homo- and copolymers, such as polyvinyl
alcohols and copolymers made from vinyl alcohol and olefin(s)
monomers such as copolymers made from ethylene and vinyl alcohol
monomers (EVOH copolymers); [0114] partially hydrolyzed vinyl
alcohol homo- and copolymers, in other words, still containing
non-hydrolyzed vinyl acetate units; [0115] polyethylene glycols;
[0116] collagen; [0117] polyethylene terephtalates (PET); [0118]
polyethylene naphtalates (PEN); [0119] polyamides; [0120]
polysaccharides, in particular cellulose polymers and their
derivatives (among which, one prefers in particular C.sub.1-C.sub.4
alkyl-celluloses and even more preferably methyl celluloses) and
possibly modified starches; [0121] polyvinyl chlorides (PVC);
[0122] polyvinylidene chlorides (PVDC); [0123] polyacrylonitrils
(PAN); [0124] polyacrylate resins, such as in particular methyl
polyacrylates; [0125] copolymers of which at least one of the
monomers is of the acrylate type; [0126] and their mixtures.
[0127] By "continuous" layer is meant a layer such that each
catalyst grain is fully coated or covered by said layer. The
thickness of the layer may be variable between different grains or
at the surface of one and the same grain, but it is never equal to
zero at any point of each catalyst grain, and preferably it is
never locally (in other words, at any point) less than 30% of the
average thickness of the layer.
[0128] As stated above, the protective layer is preferably made up
entirely by one or several film forming polymer(s).
[0129] Polyvinyl alcohols and copolymers made of vinyl alcohol and
olefin(s) monomers are especially preferred. Among the latter,
especially copolymers made up of ethylene and vinyl alcohol
monomers or EVOH copolymers are preferred.
[0130] As stated above, the average thickness of the protective
layer according to the invention ranges preferably from 0.1 to 10
.mu.m. More preferably, the average thickness of the protective
layer ranges from 0.2 to 10 .mu.m, and even better from 0.5 to 8
.mu.m.
[0131] The total amount of film forming polymer covering the
activated hydroconversion catalyst according to the invention
represents from 0.1 to 4% by weight, preferably from 0.5 to 4% by
weight, and in an even more preferred way from 1 to 3% by weight,
with respect to the total weight of the initial catalyst (in other
words, with respect to the unprotected activated catalyst, before
being covered by the protective layer according to the
invention).
[0132] Needless to say, all what has been described above
concerning the protection process also applies to the catalyst
protected according to the invention.
[0133] The examples that follow are given as mere illustrations of
this invention.
EXAMPLES
[0134] The examples below have been carried out using a commercial
regenerated hydrotreatment catalyst, that contains 20% by weight of
MoO.sub.3, and 5% by weight of CoO on alumina support, and which is
made of cylindrical shaped extruded particles with an average
diameter in number of 1.3 mm and an average length in number of 3.2
mm.
[0135] Activation of the catalyst: this catalyst has been
introduced in a rotating oven fed with a gaseous sulfo-reduction
mixture of hydrogen and hydrogen sulfide at partial pressures
respectively of 0.810.sup.5 and 0.210.sup.5 Pa, with the gas and
the solid circulating in counter-current flow. Sulfuration of the
solid is achieved by a progressive increase of the temperature
during the displacement of the solid matter inside the turning
tube, up to a maximum temperature of 330.degree. C., with a
residence time inside the oven being about 4 hours. After cooling
the solid at reactive atmosphere and nitrogen purge, it is placed
in contact with nitrogen diluted air so that its temperature
remains below 45.degree. C.
[0136] The activated catalyst thus obtained is designated below as
catalyst A. It has a sulfur content of 10.2% by weight, which
corresponds to a sulfuration stoichiometry of the metal sites of
95%.
EXAMPLE 1 (AS PER THE INVENTION)
[0137] Catalyst A has been treated as follows:
[0138] 3 kg of catalyst A has been placed in a stainless steel
perforated drum with a volume of 18 liters (useful volume of 5 L)
at a rotation speed of 20 rotations/minute, through which passes in
full a hot air flow of 160 m.sup.3/hr at 90.degree. C. to keep the
catalyst bed at 70.degree. C. during pulverization. The hot air
flow takes place in parallel to the pulverization jet, and in the
same direction (descending flow).
[0139] 900 g of an EVOH polyethylene-poly vinyl alcohol copolymer
solution (marketed under the name of EXCEVAL by the Kuraray
company) at 5% by weight in water have been injected onto the
catalyst particles by means of a two-fluid atomization nozzle with
a solution flow rate of 7 g/min.
[0140] The water evaporates continuously which leads to the
formation of a polymer layer or coating at the surface of the
catalyst particles.
[0141] Following the full injection of the liquid, the catalyst is
still stirred for 30 minutes at 70.degree. C. to complete its
drying, then cooled at ambient temperature.
[0142] In this way, catalyst B according to the invention has been
obtained; the particles are covered with a continuous layer of poly
ethylene-polyvinyl alcohol copolymer for which the average
thickness is 5 .mu.m, as observed by scan electron microscopy.
[0143] Analysis of catalyst B shows that it contains 0.9% of carbon
which corresponds to 1.5% by weight of polymer deposited on the
catalyst with respect to initial catalyst A.
EXAMPLE 2 (COMPARATIVE)
[0144] Catalyst A has been treated as follows:
[0145] 3 kg of catalyst A have been placed in an unperforated
stainless steel drum with a volume of 18 liters (useful volume of 5
L), at a rotation speed of 20 rotations/minute, and a hot air flow
of 160 m.sup.3/hr at 95.degree. C. is directed onto the surface of
the catalyst bed to keep it at 55.degree. C. during pulverization.
The hot air enters through an inlet located inside the drum, and
exits via the opening located in the front of the drum, without
passing through the catalyst bed (leached bed), which explains that
the heat exchange is not as good, and consequently the temperature
is not as high inside the catalyst bed.
[0146] 900 g of an EVOH polyethylene-poly vinyl alcohol copolymer
solution (marketed under the name of EXCEVAL by the Kuraray
company) at 5% by weight in water have been injected onto the
catalyst particles by means of an atomization nozzle with a
solution flow rate of 5 g/min.
[0147] The water evaporates continuously which leads to the
formation of a polymer layer or coating at the surface of the
catalyst particles.
[0148] Following the full injection of the liquid, the catalyst is
still stirred for 30 minutes at 55.degree. C. to complete its
drying, then cooled at ambient temperature.
[0149] In this way catalyst C has been obtained, which is not in
accordance with the invention, for which the particles are covered
with a non-continuous layer of polyethylene-poly vinyl alcohol
copolymer for which the average thickness is 6 .mu.m as observed by
scan electron microscopy, but which shows very considerable local
thickness variations. In particular, we noticed the existence of
points at the surface of the catalyst particles where the presence
of a polymer layer was not detectable. At the points where a
polymer layer is present, its thickness varies greatly, going from
less than 0.1 .mu.m to about 15 .mu.m.
[0150] Analysis of catalyst C shows that it contains 0.8% by weight
of carbon which corresponds to 1.4% by weight of polymer deposited
on the catalyst with respect to initial catalyst A.
EXAMPLE 3 (COMPARATIVE)
[0151] Catalyst A has been treated as follows:
[0152] 3 kg of catalyst A have been placed in an unperforated
stainless steel drum with a volume of 18 liters (useful volume of 5
L), at a rotation speed of 20 rotations/minute, and a hot air flow
of 150 m.sup.3/hr at 80.degree. C. is directed onto the surface of
the catalyst bed to keep it at 50.degree. C. during pulverization.
The hot air enters through an inlet located inside the drum, and
exits via the opening located in the front of the drum, without
passing through the catalyst bed (leached bed).
[0153] A solution of 750 g of polyacrylate resin at 20% by weight
in ethyl acetate has been injected onto the catalyst particles
using an atomization nozzle with a solution flow rate of 4
g/min.
[0154] The solvent evaporates continuously which leads to the
formation of a polymer layer or coating at the surface of the
catalyst particles.
[0155] Following the full injection of the liquid, the catalyst is
still stirred for 15 minutes at 50.degree. C. to complete its
drying, then cooled at ambient temperature.
[0156] In this way, catalyst D was obtained, which is not in
accordance with the invention, for which the particles are covered
with a non-continuous layer of polyacrylate resin for which the
average thickness is 20 .mu.m as observed by scan electron
microscopy, but which shows very considerable local thickness
variations. In particular, we noticed the existence of points at
the surface of the catalytic particles where the presence of a
polymer layer was not detectable. At the points where a polymer
layer is present, its thickness varies greatly, going from less
than 0.1 .mu.m to about 50 .mu.m.
[0157] Analysis of catalyst D shows that it contains 3% by weight
of carbon which corresponds to 5% by weight of polymer deposited on
the catalyst with respect to initial catalyst A.
EXAMPLE 4 (AS PER THE INVENTION)
[0158] Catalyst A has been treated as follows:
[0159] 3 kg of catalyst A have been placed in a perforated
stainless steel drum with a volume of 18 liters (useful volume of 5
L), at a rotation speed of 20 rotations/minute, with a hot air flow
of 150 m.sup.3/hr running fully through it at 55.degree. C. to keep
the catalyst bed at 45.degree. C. during pulverization. The hot air
flow takes place in parallel to the pulverization jet, and in the
same direction (descending flow).
[0160] A solution of 750 g of polyacrylate resin at 20% by weight
in ethyl acetate has been injected onto the catalyst particles
using an atomization nozzle with a solution flow rate of 4
g/min.
[0161] The solvent evaporates continuously which leads to the
formation of a polymer layer or coating at the surface of the
catalyst particles.
[0162] Following the full injection of the liquid, the catalyst is
still stirred for 30 minutes at 45.degree. C. to complete its
drying, then cooled at ambient temperature.
[0163] In this way, catalyst E as per the invention was obtained,
for which the particles are covered with a continuous layer of
polyacrylate resin for which the average thickness is 18 .mu.m as
observed by scan electron microscopy.
[0164] Analysis of catalyst E shows that it contains 3% by weight
of carbon which corresponds to 5% by weight of polymer deposited on
the catalyst with respect to initial catalyst A.
EXAMPLE 5 (COMPARATIVE)
[0165] In this example, a comparative catalyst F has been prepared,
by applying to activated catalyst A a process identical to the one
described in example 1 above, by replacing the polymer aqueous
solution by deionized water (not containing any polymer):
[0166] 3 kg of catalyst A have been placed in a fully perforated
stainless steel drum with a volume of 18 liters (useful volume of 5
L), at a rotation speed of 20 rotations/minute; a hot air flow of
160 m.sup.3/hr at 90.degree. C. passes fully through it to keep the
catalyst bed at 70.degree. C. during pulverization. The hot air
flow takes place in parallel to the pulverization jet, and in the
same direction (descending flow).
[0167] Then, 900 g of deionized water have been injected onto the
catalyst particles using a two-fluid atomization nozzle with a flow
rate of 7 g/min.
[0168] The water evaporates continuously. Following the full
injection of the liquid, the catalyst is still stirred for 30
minutes at 70.degree. C. to complete its drying, then cooled at
ambient temperature.
[0169] Consequently, comparative catalyst F has been obtained.
[0170] Analysis of catalyst F shows that it contains at least 0.1%
by weight of carbon.
EXAMPLE 6: (COMPARATIVE)
[0171] In this example, a comparative catalyst F' has been prepared
by applying to activated catalyst A a process similar to the one
described in example 5 above:
[0172] 3 kg of catalyst A have been placed in a fully perforated
stainless steel drum with a volume of 18 liters (useful volume of 5
L), at a rotation speed of 20 rotations/minute, a hot air flow of
160 m.sup.3/hr at 130.degree. C. passes fully through it to keep
the catalyst bed at 100.degree. C. during pulverization. The hot
air flow takes place in parallel to the pulverization jet, and in
the same direction (descending flow).
[0173] Then, 900 g of deionized water have been injected onto the
catalyst particles using a two-fluid atomization nozzle with a flow
rate of 7 g/min.
[0174] The water evaporates continuously. Following the total
injection of the liquid, the catalyst is still stirred for 30
minutes at 100.degree. C. to complete its drying, then cooled at
ambient temperature.
[0175] Consequently comparative catalyst F' has been obtained.
[0176] Analysis of catalyst F' shows that it contains at least 0.1%
by weight of carbon.
EXAMPLE 7 (COMPARATIVE)
[0177] In this example, a comparative catalyst G has been prepared
by treating catalyst A as follows:
[0178] 1 kg of catalyst A has been placed in an unperforated
stainless steel drum with a volume of 3 liters at a rotation speed
of 12 rotations/minute, at a temperature of 120.degree. C. under a
nitrogen atmosphere.
[0179] Then, 200 g of mineral oil (marketed under the name of Lube
Oil 600 Neutral by Total, with a viscosity at 40.degree. C. of 120
cP) have been pulverized onto the catalyst, with a flow rate of 6
g/min.
[0180] Following full injection of the oil, the catalyst is cooled
at ambient temperature.
[0181] In this way comparative catalyst G was obtained.
EXAMPLE 8
Characterization of the Obtained Catalysts
[0182] The properties of catalysts A to G described in examples 1
to 7 above have been assessed, by determining the following
parameters for each:
[0183] Critical Self-heating Temperature--CSHT:
[0184] This parameter characterizes the self-heating properties of
the activated catalyst, using a procedure similar to the UN
standard (test described in the "Recommendation on the transport of
dangerous goods. Manual for Tests and Criteria", ISSN 1014-7160,
Section 33.3 document). This CSHT test can be conducted according
to two variants, for which only the volume of the sample varies.
The test procedure is as follows:
[0185] Catalyst samples have been placed in a cubic metal grill
box, which lets air pass through. A thermocouple is placed in the
sample, and the box is placed in an oven equipped with
thermostat.
[0186] If the temperature of the catalyst is not higher by more
than 60.degree. C. over that of the oven for a 24 hr period, the
test is repeated with a new sample of the same catalyst and by
increasing the oven temperature by 10.degree. C.
[0187] This determines temperature T1 which corresponds to the
highest oven temperature attained, for which the catalyst
temperature is not higher than T1+60.degree. C.
[0188] The critical Self-heating Temperature--CSHT is defined as
follows:
CSHT(.degree. C.)=T1(.degree. C.)+5.degree. C.
[0189] For the first variant of the test, the cubic box has a
volume of 1 L and the temperature thus obtained was referred to as
CSHT-1 L. For the second variant of the test, the cubic box has a
volume of 15 mL and the temperature thus obtained was referred to
as CSHT-15 ml.
[0190] Hydrosulfuration Activity:
[0191] Hydrosulfuration activity of each catalyst has been
determined in a pilot unit.
[0192] The feedstock used is a "straight run" diesel fuel which has
the following characteristics:
TABLE-US-00001 Sulfur content (ppm by weight) 11600 Nitrogen
content (ppm by weight) 199 Density (g/mL) 0.859
[0193] For each sample, the catalyst volume used for the test is 10
mL.
[0194] When starting the hydrodesulfuration test, the diesel fuel
feedstock is injected with a VVH=3 h.sup.-1 and the reactor is
placed under hydrogen pressure (3010.sup.5 Pa), then the
temperature is increased by 0.5.degree. C./min up to 320.degree. C.
The 320.degree. C. level is held for 5 hrs before proceeding with
the test conditions. This standard startup stage for an activated
catalyst is sufficient to deprotect the catalyst grains.
[0195] The test feedstock is then injected to start the actual
test. The test conditions were as follows: pressure of 4 MPa (40
bars), H.sub.2/gazole (diesel fuel) ratio of 300, VVH=2h.sup.-1,
temperature of 357 to 367.degree. C., test duration of 6 days.
[0196] The sulfur content of the feedstock is measured at the
outlet of the unit by means of a UV fluorescence analyser. The
apparent constants of the desulfuration reaction have been
calculated according to the E1 formula below:
K v = ( 1 .alpha. - 1 ) ( 1 S .alpha. - 1 - 1 S 0 .alpha. - 1 ) *
VVH ( E 1 ) ##EQU00001##
where
[0197] K.sub.v=apparent reaction constant
[0198] .alpha.=order of the reaction (considered equal to 1.2)
[0199] S=sulfur content of the effluents
[0200] S.sub.0=sulfur content of the feedstock
[0201] VVH=hourly volume speed of the liquid feedstock
[0202] The performances of each sample have been assessed with
respect to that of a reference catalyst. For that, the Relative
Volume Activity (RVA) has been calculated according to the E2
formula that follows:
RVA = Kv ( sample ) Kv ( reference ) .times. 100 ( E 2 )
##EQU00002##
[0203] As reference, the value K.sub.v of 100 has been assigned to
activated catalyst A.
[0204] The Low Temperature SO.sub.2 Emissions:
[0205] A 25 g catalyst sample is weighed then placed in a 1 L
container with air that is then sealed using a plug equipped with a
septum. The container is then placed in a heat chamber with
thermostat at 50.degree. C. for 24 hrs. After 24 hrs, the container
is removed and left to cool at ambient temperature. Then a SO.sub.2
analysis is made for the gas contained in the container, by
sampling through the septum using a syringe. The gas analysis gives
immediately the ppm result of SO.sub.2 emitted by the catalyst.
[0206] For each catalyst, immediately after its preparation the two
critical self-heating temperatures (CSHT-1 L and CSHT-15 mL), the
RVA activity and the SO.sub.2 formation were determined.
The results obtained for each catalyst are put together in Table 1
below:
TABLE-US-00002 TABLE 1 Protective CSHT CSHT Activity Emissions
Catalyst layer Equipment 1 L 15 mL RVA SO.sub.2 A (initial
65.degree. C. 115.degree. C. 100 150 ppm catalyst) B EVOH
Perforated 125.degree. C. >220.degree. C. 98 0.2 ppm (invention)
drum C EVOH Unperforated 85.degree. C. 155.degree. C. 99 15 ppm
(comparative) drum D Polyacrylate Unperforated 85.degree. C.
145.degree. C. 84 50 ppm (comparative) drum E Polyacrylate
Perforated 105.degree. C. 205.degree. C. 88 4 ppm (invention) drum
F -- Perforated 65.degree. C. 115.degree. C. 101 150 ppm
(comparative) drum F' -- Perforated 85.degree. C. 145.degree. C. 98
460 ppm (comparative) drum G Oil Unperforated 85.degree. C.
145.degree. C. 98 120 ppm (comparative) drum
[0207] The results above show that activated catalyst A has a low
critical self-heating temperature (65.degree. C.), typical for this
type of catalyst at the newly activated state, then
air-stabilized.
[0208] Protection provided with a layer of film forming polymer
(catalyst B and catalyst E as per the invention), obtained with the
process according to the invention, enables to reduce in a
particularly efficient way the self-heating of the activated
catalyst A: the critical self-heating temperature for box 1 L is
increased considerably, since it is 125.degree. C. for catalyst B
and 105.degree. C. for catalyst E.
[0209] In addition, these two catalysts show an SO.sub.2 emission
well below initial catalyst A, and below the 5 ppm threshold.
[0210] In comparison, catalysts C and D which are not in accordance
with the invention, for which the protection has been done in an
unperforated drum, for which the air flow does not pass through the
catalyst grains, have a self-heating feature that is quite higher,
with CSHT-1 L temperatures of 85.degree. C. In addition, the
SO.sub.2 emission remains high in both cases (15 and 50 ppm).
Consequently, these two examples show the importance of conducting
the process according to the invention by having an air flow
circulate through the catalyst particles during pulverization of
the composition containing the film forming polymer.
[0211] Catalysts F and F' correspond to "blank" tests, that permit
to verify easily the impact of the coating conditions themselves
(pulverization of water and hot air flow) on the properties of the
catalyst. The self-heating properties of these two catalysts, for
which the respective CSHT-1 L are 65 and 85.degree. C., are
coherent with the passivation methods by the active phase
oxidation, already known by the prior state of the art. The
SO.sub.2 emissions are greatly increased for catalyst F' which can
be explained by the relatively high oxidative stabilization of the
active phase, when catalyst A has been placed at 100.degree. C.
under an air flow.
[0212] The use of mineral oil as protective material also leads to
a moderate increase of the critical self-heating temperature and a
small reduction of the SO.sub.2 emissions, at values that remain
low in comparison with those reached for catalysts B and E
according to the invention using film forming polymers.
* * * * *