U.S. patent application number 14/553007 was filed with the patent office on 2015-05-28 for process for the hydrotreatment of diesel employing a concatenation of catalysts.
This patent application is currently assigned to IFP ENERGIES NOUVELLES. The applicant listed for this patent is IFP ENERGIES NOUVELLES. Invention is credited to Emmanuelle GUILLON, Philippe ROCHER, Magalie ROY-AUBERGER.
Application Number | 20150144533 14/553007 |
Document ID | / |
Family ID | 50137832 |
Filed Date | 2015-05-28 |
United States Patent
Application |
20150144533 |
Kind Code |
A1 |
ROY-AUBERGER; Magalie ; et
al. |
May 28, 2015 |
PROCESS FOR THE HYDROTREATMENT OF DIESEL EMPLOYING A CONCATENATION
OF CATALYSTS
Abstract
A process for the hydrotreatment of a diesel type hydrocarbon
feed containing nitrogen-containing compounds is described,
comprising a first step in which the feed is brought into contact
with a catalyst in its oxide form, then a second step in which the
feed is brought into contact with a dried catalyst comprising at
least one organic compound containing oxygen and/or nitrogen.
Inventors: |
ROY-AUBERGER; Magalie;
(Nivolas-Vermelle, FR) ; GUILLON; Emmanuelle;
(Vourles, FR) ; ROCHER; Philippe; (Soucieu En
Jarrest, FR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
IFP ENERGIES NOUVELLES |
Rueil-Malmaison |
|
FR |
|
|
Assignee: |
IFP ENERGIES NOUVELLES
Rueil-Malmaison
FR
|
Family ID: |
50137832 |
Appl. No.: |
14/553007 |
Filed: |
November 25, 2014 |
Current U.S.
Class: |
208/264 |
Current CPC
Class: |
C10G 67/02 20130101;
C10G 45/08 20130101; B01J 23/88 20130101; B01J 35/1038 20130101;
C10G 2300/1059 20130101; B01J 37/28 20130101; B01J 37/0018
20130101; C10G 65/04 20130101; C10G 2300/202 20130101; B01J 35/1019
20130101; B01J 21/04 20130101; B01J 35/1042 20130101; B01J 37/0205
20130101; B01J 37/26 20130101; B01J 23/883 20130101; B01J 37/0203
20130101; C10G 2300/1055 20130101 |
Class at
Publication: |
208/264 |
International
Class: |
C10G 67/02 20060101
C10G067/02; C10G 65/04 20060101 C10G065/04 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 28, 2013 |
FR |
13/61.801 |
Claims
1. A process for the hydrotreatment of a hydrocarbon feed
containing nitrogen-containing compounds in an amount of more than
150 ppm by weight and having a weighted average temperature in the
range 250.degree. C. to 380.degree. C., comprising the following
steps: a) bringing said hydrocarbon feed into contact, in the
presence of hydrogen, with at least one first catalyst comprising
an alumina support, phosphorus, and an active phase formed by at
least one metal from group VIB in the oxide form and at least one
metal from group VIII in the oxide form, said first catalyst being
prepared in accordance with a process comprising at least one
calcining step; b) bringing the effluent obtained in step a) into
contact, in the presence of hydrogen, with at least one second
catalyst comprising an alumina support, phosphorus, an active phase
formed by at least one metal from group VIB and at least one metal
from group VIII, and at least one organic compound containing
oxygen and/or nitrogen, said second catalyst being prepared in
accordance with a process comprising the following steps: i)
bringing at least one component of a metal from group VIB, at least
one component of a metal from group VIII, phosphorus and at least
one organic compound containing oxygen and/or nitrogen into contact
with the support, so as to obtain a catalyst precursor; ii) drying
said catalyst precursor obtained from step i) at a temperature of
less than 200.degree. C., without subsequent calcining; in order to
obtain a hydrotreated effluent.
2. The process according to claim 1 in which, for the catalyst of
step a) or b), the metal from group VIB is molybdenum and the metal
from group VIII is selected from cobalt, nickel and a mixture of
these two elements.
3. The process according to claim 1 in which, for the catalyst of
step a) or b), the quantity of metal from group VIB is in the range
5% to 40% by weight of oxide of the metal from group VIB with
respect to the total catalyst weight, the quantity of metal from
group VIII is in the range 1% to 10% by weight of oxide of the
metal from group VIII with respect to the total catalyst weight,
and the quantity of phosphorus is in the range 0.1% to 10% by
weight of P.sub.2O.sub.5 with respect to the total catalyst
weight.
4. The process according to claim 1, in which the catalyst of step
a) or b) further contains at least one dopant selected from boron
and fluorine and a mixture of boron and fluorine.
5. The process according to claim 1, in which the organic compound
is one or more selected from a carboxylic acid, an alcohol, an
aldehyde, an ester, an amine, an aminocarboxylic acid, an
aminoalcohol, a nitrile or an amide.
6. The process according to claim 5, in which the organic compound
is one or more selected from ethylene glycol, glycerol,
polyethylene glycol (with a molecular weight of 200 to 1500),
acetophenone, 2,4-pentanedione, pentanole, acetic acid, maleic
acid, oxalic acid, tartaric acid, formic acid, citric acid and
C1-C4 dialkyl succinate.
7. The process according to claim 5, in which the organic compound
comprises at least the combination of C1-C4 dialkyl succinate and
acetic acid.
8. The process according to claim 5, in which the organic compound
comprises at least citric acid.
9. The process according to claim 1, in which the catalyst of step
a) or b) has also undergone a sulphurizing step.
10. The process according to claim 1, in which the quantity of
basic nitrogen in the feed is 50 ppm or more.
11. The process according to claim 1, in which the feed is a feed
obtained from catalytic cracking, a coker or from visbreaking.
12. The process according to claim 1, in which each of steps a) and
b) is carried out at a temperature in the range 180.degree. C. to
450.degree. C., at a pressure in the range 0.5 to 10 MPa, at an
hourly space velocity in the range 0.1 to 20 h.sup.-1 and with a
hydrogen/feed ratio, expressed as the volume of hydrogen measured
under normal temperature and pressure conditions, per volume of
liquid feed in the range 50 L/L to 2000 L/L.
13. The process according to claim 1, in which step a) is carried
out in a first zone containing the first catalyst which occupies a
volume V1, and step b) is carried out in a second zone containing
the second catalyst which occupies a volume V2, the distribution of
the volumes, V1/V2, being in the range 10% by volume/90% by volume
to 50% by volume/50% by volume for the first and second zone
respectively.
14. The process according to claim 1, in which step i) of step b)
comprises the following steps in succession: i') impregnating an
alumina support with at least one solution containing at least one
metal from group VIB, at least one metal from group VIII and said
phosphorus in order to obtain an impregnated support; i'') drying
the impregnated support obtained in step i') at a temperature of
less than 180.degree. C. without subsequent calcining in order to
obtain a dried impregnated support; i''') impregnating the dried
impregnated support obtained in step i'') with an impregnation
solution comprising at least one organic compound containing oxygen
and/or nitrogen in order to obtain an impregnated catalytic
precursor; i'''') allowing the impregnated catalytic precursor
obtained in step i''') to mature, in order to obtain said catalyst
precursor.
15. The process according to claim 1, in which the effluent
obtained in step a) undergoes a separation step in order to
separate a heavy fraction and a light fraction containing the
H.sub.2S and NH.sub.3 formed during step a), said heavy fraction
then being introduced into step b).
Description
[0001] The present invention relates to the field of processes for
the hydrotreatment of a diesel type feed using a concatenation of
catalysts. The aim of the process is to produce desulphurized and
denitrogenated diesel. The hydrotreatment process of the invention
is particularly suitable for the hydrotreatment of feeds comprising
high levels of nitrogen.
[0002] Usually, a catalyst for the hydrotreatment of hydrocarbon
cuts is intended to eliminate the sulphur-containing or
nitrogen-containing compounds contained therein in order, for
example, to ensure that an oil product meets the required
specifications (sulphur content, aromatics content, etc.) for a
given application (automobile fuel, gasoline or diesel, domestic
fuel, jet fuel). The composition and the use of hydrotreatment
catalysts have been particularly thoroughly described in the
article by B. S Clausen, H. T. Topsoe, and F. E. Massoth, published
in Catalysis Science and Technology, volume 11 (1996),
Springer-Verlag. The hydrotreatment catalysts generally have
hydrodesulphurizing functions and hydrogenating functions based on
a sulphide of metals from groups VIB and VIII.
[0003] The tightening of automobile pollution standards in the
European community (Official Journal of the European Union, L76,
22.sup.nd March 2003, Directive 2003/70/CE, pages L76/10-L76/19)
has required refiners to reduce the sulphur content in diesel fuels
and gasolines by a very large extent (a maximum of 10 parts per
million by weight (ppm) of sulphur at 1.sup.st January 2009, as
opposed to 50 ppm on 1.sup.st January 2005). Furthermore, refiners
are often forced to use feeds which are more and more refractory to
hydrotreatment processes, on the one hand because crudes are
getting heavier and heavier and as a result contain more and more
impurities, and on the other hand due to the increase in the number
of conversion units in the refineries. In fact, they generate cuts
which are more difficult to hydrotreat than cuts obtained directly
from atmospheric distillation because of the high levels of
aromatic, nitrogen-containing and sulphur-containing compounds.
These cuts thus require catalysts which have hydrodesulphurizing
and hydrogenating functions which are greatly improved compared
with traditional catalysts.
[0004] Adding an organic compound to hydrotreatment catalysts to
improve their activity is now well known to the skilled person. A
number of patents protect the use of various ranges of organic
compounds such as mono-, di- or poly-alcohols, which may be
etherified (WO 96/41848, WO 01/76741, U.S. Pat. No. 4,012,340, U.S.
Pat. No. 3,954,673, EP 0601722). Catalysts modified with C2-C14
monoesters are described in patent applications EP 466568 and EP
1046424.
[0005] Other patents show that a specific concatenation of
catalysts in the same reactor may be advantageous.
[0006] Thus, patent application US 2011/0079542 discloses that
replacement of a portion of a reference HDS catalyst at the head of
the bed by a catalyst with a lower activity does not modify the
performances of the overall charge compared with 100% reference
catalyst, because over the first portion of catalytic bed, the
reaction occurs on non-refractory sulphur-containing species and
does not require a high performance catalyst.
[0007] Patent EP 0651041 discloses the advantage of linking
together beds of catalysts with different particle shapes in a
concatenation.
[0008] The present invention concerns a process for the
hydrotreatment of a feed of the diesel type by using a specific
concatenation of at least two different types of catalysts, which
can increase the overall activity and overall stability of the
hydrotreatment process compared with a hydrotreatment process using
the same quantity and the same operating conditions as just one of
these two types of catalysts.
[0009] The term "hydrotreatment" means reactions in particular
encompassing hydrodesulphurization (HDS), hydrodenitrogenation
(HDN) and hydrogenation of aromatics (HDA).
[0010] In accordance with the process of the invention, the feed is
initially brought into contact with a first type of catalyst
comprising phosphorus and an active phase in its oxide form, i.e.
said first catalyst is prepared using a process comprising at least
one calcining step after impregnation of metallic salts. This first
type of catalyst is termed the "catalyst in the oxide form" or
"calcined catalyst".
[0011] The feed is then brought into contact with a second type of
catalyst which has been prepared by introducing phosphorus, active
phase and an organic compound containing oxygen and/or nitrogen
followed by a drying step, without subsequent calcining. It should
be noted that this second type of catalyst does not undergo
calcining, and so the active phase is not in its oxide form. This
second type of catalyst is known as an "additive-containing
catalyst".
[0012] More particularly, the present invention concerns a process
for the hydrotreatment of a hydrocarbon feed containing
nitrogen-containing compounds in an amount of more than 150 ppm by
weight and having a weighted average temperature in the range
250.degree. C. to 380.degree. C., comprising the following
steps:
[0013] a) bringing said hydrocarbon feed into contact, in the
presence of hydrogen, with at least one first catalyst comprising
an alumina support, phosphorus, and an active phase formed by at
least one metal from group VIB in the oxide form and at least one
metal from group VIII in the oxide form, said first catalyst being
prepared in accordance with a process comprising at least one
calcining step;
[0014] b) bringing the effluent obtained in step a) into contact,
in the presence of hydrogen, with at least one second catalyst
comprising an alumina support, phosphorus, an active phase formed
by at least one metal from group VIB and at least one metal from
group VIII, and at least one organic compound containing oxygen
and/or nitrogen, said second catalyst being prepared in accordance
with a process comprising the following steps:
[0015] i) bringing at least one component of a metal from group
VIB, at least one component of a metal from group VIII, phosphorus
and at least one organic compound containing oxygen and/or nitrogen
into contact with the support, so as to obtain a catalyst
precursor;
[0016] ii) drying said catalyst precursor obtained from step i) at
a temperature of less than 200.degree. C., without subsequent
calcining; in order to obtain a hydrotreated effluent.
[0017] It has been observed that although the additive-containing
catalysts of an organic compound generally have an improved
hydrotreatment capability compared with catalysts without
additives, these catalysts are more easily inhibited by
nitrogen-containing molecules, and in particular by basic
nitrogen-containing molecules contained in the feed, than catalysts
without additives. This inhibition has the consequence of reducing
the activity and stability of the additive-containing catalyst over
time, thus reducing their hydrotreatment capability.
[0018] The Applicant has developed a process for the hydrotreatment
of a diesel type feed, comprising a concatenation of catalysts
which can be used to carry out, firstly, a hydrotreatment over a
catalyst in its oxide form (calcined catalyst) which has a good
hydrodesulphurization and hydrodenitrogenation activity. This first
type of catalyst is in particular less inhibited by refractory
basic nitrogen-containing molecules and thus more active in
hydrodenitrogenation than an additive-containing catalyst. This
means that an intense hydrodenitrogenation can be carried out in
the first step of the process of the invention and thus relieves
the additive-containing catalyst of the second step which is
brought into contact with the effluent leaving from this first
step. The hydrotreatment is then continued by bringing the feed
which has been freed from a large part of its nitrogen-containing
molecules and a portion of its sulphur-containing molecules into
contact with an additive-containing catalyst which is particularly
active in HDS, thus allowing the intense hydrotreatment to be
completed. Because the feed is brought into contact with a catalyst
in the oxide form before being brought into contact with an
additive-containing catalyst, the additive-containing catalyst is
less inhibited by nitrogen-containing molecules and thus more
active and stable over time. The specific concatenation can thus
protect the additive-containing catalyst which is highly active for
HDS with a catalyst in the oxide form which is highly active in
HDN, which has the result of increasing the overall activity and
overall stability of the catalytic concatenation compared with a
catalytic system containing only additive-containing catalysts.
Thus, the overall activity is increased as the hourly space
velocity (volume of feed which can be treated per unit time) can be
increased or, alternatively, less catalyst could be used to treat
the same volume of feed. In addition, because of the increase in
activity, the temperature necessary to obtain a desired sulphur
content (for example 10 ppm of sulphur) can be reduced. Similarly,
the overall stability is increased, as the cycle time is
longer.
[0019] The hydrotreatment process of the invention is particularly
suitable for the hydrotreatment of feeds comprising high organic
nitrogen contents, such as feeds obtained from catalytic cracking,
from a coker or from visbreaking.
[0020] The process of the present invention can be used to produce
a hydrotreated hydrocarbon cut, i.e. free of any
nitrogen-containing compounds, and at the same time desulphurized
to contents of 10 ppm of sulphur or less. The term "ppm of sulphur"
(or nitrogen) as used throughout the remainder of the text means
the ppm by weight with respect to elemental sulphur (or elemental
nitrogen), irrespective of the organic molecule or molecules in
which the sulphur (or nitrogen) is engaged. Preferably, in the
process of the invention, the hydrodesulphurization conversion is
more than 98%, preferably more than 99%. The specific concatenation
of catalysts in the process of the invention can thus be used to
carry out an intense hydrotreatment, and in particular an intense
hydrodesulphurization of diesel fuels in order to obtain diesel
which complies with the specifications (ULSD, Ultra Low Sulphur
Diesel).
[0021] In a variation, for the catalyst of step a) or b), the metal
from group VIB is molybdenum and the metal from group VIII is
selected from cobalt, nickel and a mixture of these two
elements.
[0022] In a variation, for the catalyst of step a) or b), the
quantity of metal from group VIB is in the range 5% to 40% by
weight of oxide of the metal from group VIB with respect to the
total catalyst weight, the quantity of metal from group VIII is in
the range 1% to 10% by weight of oxide of the metal from group VIII
with respect to the total catalyst weight, and the quantity of
phosphorus is in the range 0.1% to 10% by weight of P.sub.2O.sub.5
with respect to the total catalyst weight.
[0023] In a variation, the catalyst of step a) or b) further
contains at least one dopant selected from boron and fluorine and a
mixture of boron and fluorine.
[0024] In a variation, the organic compound is one or more selected
from a carboxylic acid, an alcohol, an aldehyde, an ester, an
amine, an aminocarboxylic acid, an aminoalcohol, a nitrile or an
amide; preferably it is one or more selected from ethylene glycol,
glycerol, polyethylene glycol (with a molecular weight of 200 to
1500), acetophenone, 2,4-pentanedione, pentanole, acetic acid,
maleic acid, oxalic acid, tartaric acid, formic acid, citric acid
and C1-C4 dialkyl succinate; particularly preferably, it comprises
at least the combination of C1-C4 dialkyl succinate and acetic
acid. In accordance with another particularly preferred variation,
the organic compound comprises at least citric acid.
[0025] In a variation, the catalyst of step a) or b) has also
undergone a sulphurizing step.
[0026] In a variation, the quantity of basic nitrogen in the feed
is 50 ppm or more.
[0027] In a variation, the feed is a feed obtained from catalytic
cracking, a coker or from visbreaking.
[0028] In a variation, each of steps a) and b) is carried out at a
temperature in the range 180.degree. C. to 450.degree. C., at a
pressure in the range 0.5 to 10 MPa, at an hourly space velocity in
the range 0.1 to 20 h.sup.-1 and with a hydrogen/feed ratio,
expressed as the volume of hydrogen measured under normal
temperature and pressure conditions, per volume of liquid feed in
the range 50 L/L to 2000 L/L.
[0029] In a variation, step a) is carried out in a first zone
containing the first catalyst which occupies a volume V1, and step
b) is carried out in a second zone containing the second catalyst
which occupies a volume V2, the distribution of the volumes, V1/V2,
being in the range 10% by volume/90% by volume to 50% by volume/50%
by volume respectively for the first and second zone.
[0030] In a variation, step i) of step b) comprises the following
steps in succession:
[0031] i') impregnating an alumina support with at least one
solution containing at least one metal from group VIB, at least one
metal from group VIII and said phosphorus in order to obtain an
impregnated support;
[0032] i'') drying the impregnated support obtained in step i') at
a temperature of less than 180.degree. C. without subsequent
calcining in order to obtain a dried impregnated support;
[0033] i''') impregnating the dried impregnated support obtained in
step i'') with an impregnation solution comprising at least one
organic compound containing oxygen and/or nitrogen in order to
obtain an impregnated catalytic precursor;
[0034] i'''') allowing the impregnated catalytic precursor obtained
in step i''') to mature, in order to obtain said catalyst
precursor.
[0035] In a variation, the effluent obtained in step a) undergoes a
separation step in order to separate a heavy fraction and a light
fraction containing the H.sub.2S and NH.sub.3 formed during step
a), said heavy fraction then being introduced into step b).
DETAILED DESCRIPTION
The Feed and the Operating Conditions
[0036] The hydrocarbon feed treated in accordance with the
hydrotreatment process of the invention has a weighted average
temperature (WAT) in the range 280.degree. C. to 350.degree. C. The
WAT is defined from the temperatures at which 5%, 50% and 70% of
the volume of the feed distils in accordance with the following
formula: WAT=(T 5%)+2.times.T 50%+4.times.T 70%)/7. The WAT is
calculated from simulated distillation values. The treated
hydrocarbon feed generally has a distillation range in the range
150.degree. C. to 500.degree. C., preferably in the range
180.degree. C. to 450.degree. C.
[0037] In the remainder of the text, we shall use the convention of
calling this feed diesel, but this designation is not at all
restrictive in nature. Any hydrocarbon feed containing sulphur and
nitrogen-containing compounds which are hydrotreatment inhibitors,
and a WAT similar to that of a diesel cut may be used in the
process of the present invention. The hydrocarbon feed may have any
chemical nature, i.e. it may have any distribution of chemical
families, in particular paraffins, olefins, naphthenes and
aromatics.
[0038] Said hydrocarbon feed comprises organic nitrogen-containing
and/or sulphur-containing molecules. The nitrogen-containing
organic molecules are either basic, such as amines, anilines,
pyridines, acridines, quinolines and their derivatives, or neutral,
such as pyrroles, indoles, carbazoles and their derivatives, for
example. In particular, it is the basic nitrogen-containing
molecules which inhibit the hydrotreatment catalysts, and in
particular the additive-containing catalysts.
[0039] The total nitrogen content (neutral and basic) in the feed
is 150 ppm or more, and is preferably in the range 200 to 6000 ppm
by weight, more preferably in the range 300 to 4000 ppm by weight
and still more preferably in the range 400 to 4000 ppm. The basic
nitrogen content is at least one third of the overall nitrogen
content.
[0040] The basic nitrogen content is generally 50 ppm or higher,
more preferably in the range 65 to 2000 ppm by weight and still
more preferably in the range 100 to 2000 ppm.
[0041] The sulphur content in the feed is generally in the range
0.01% to 5% by weight, preferably in the range 0.2% to 4% by weight
and more preferably in the range 0.25% to 3% by weight.
[0042] The treated feed generally contains very few resins; the
resins content is generally less than 1% by weight.
[0043] Said hydrocarbon feed is advantageously selected from LCO
(Light Cycle Oil, or light diesels obtained from a catalytic
cracking unit), atmospheric distillates, for example diesels
obtained from straight-run distillation of crude or from conversion
units such as fluidised bed catalytic cracking, cokers or
visbreaking units, or distillates obtained from fixed bed or
ebullated bed desulphurization or the hydroconversion of
atmospheric residues, or a mixture of said feeds as mentioned
above.
[0044] The hydrotreatment process of the invention is particularly
suitable for the hydrotreatment of feeds which are more difficult
to hydrotreat (having a high sulphur and nitrogen content) than
cuts obtained directly from atmospheric distillation of crude. The
hydrotreatment process of the invention is particularly suitable
for the hydrotreatment of feeds containing high levels of nitrogen,
in particular a high basic nitrogen content.
[0045] Preferably, said hydrocarbon feed is selected from a LCO
feed (Light Cycle Oil) obtained from fluidized bed catalytic
cracking (or FCC, Fluid Catalytic Cracking) or a cut obtained from
a coking or visbreaking process. This type of cut generally has the
following characteristics: a sulphur content of more than 0.5% by
weight, generally 0.5% to 3% by weight, a nitrogen content of more
than 150 ppm, generally in the range 200 ppm to 6000 ppm by weight,
and preferably in the range 300 ppm to 4000 ppm, and of this
nitrogen, at least 50 ppm of compounds termed basic compounds,
generally in the range 150 to 2000 ppm, and an aromatics content of
more than 25% by weight, generally 30% to 90% by weight.
[0046] The process of the invention may be carried out in one, two
or more reactors. It is generally carried out in fixed bed
mode.
[0047] When the process of the invention is carried out in two
reactors, step a) may be carried out in the first reactor traversed
by the feed, then step b) may be carried out in the second reactor
placed downstream of the first reactor. Optionally, the effluent
from step a) leaving the first reactor may undergo a separation
step in order to separate a light fraction containing H.sub.2S and
NH.sub.3 in particular, formed during the hydrotreatment, in step
a), from a heavy fraction containing partially hydrotreated
hydrocarbons. The heavy fraction obtained after the separation step
is then introduced into the second reactor for carrying out step b)
of the process of the invention. The separation step may be carried
out by distillation, flash separation or any other method which is
known to the skilled person.
[0048] When the process is carried out in a single reactor, step a)
is carried out in a first zone containing the first catalyst which
occupies a volume V1, and step b) is carried out in a second zone
containing the second catalyst which occupies a volume V2. The
percentage by volume of the first zone containing the catalyst in
the oxide form of step a) with respect to the total volume of the
zones is preferably at least 10% by volume. The percentage by
volume of the first zone containing the catalyst in the oxide form
of step a) is adjusted so as to maximize the conversion of the
inhibiting nitrogen-containing compounds, termed basic compounds.
The distribution of the volumes, V1/V2, is preferably in the range
10% by volume/90% by volume to 50% by volume/50% by volume in the
first and second zone respectively.
[0049] The metals from group VIB or group VIII used to form the
active phase of the catalysts of step a) or b) may be identical or
different in each of steps a) or b).
[0050] The operating conditions used in steps a) or b) of the
hydrotreatment process of the invention are generally as follows:
the temperature is advantageously in the range 180.degree. C. to
450.degree. C., preferably in the range 250.degree. C. to
400.degree. C., the pressure is advantageously in the range 0.5 to
10 MPa, preferably in the range 1 to 8 MPa, the hourly space
velocity (defined as the ratio of the volume flow rate of feed to
the volume of catalyst per hour) is advantageously in the range 0.1
to 20 h.sup.-1, preferably in the range 0.2 to 5 h.sup.-1, and the
hydrogen/feed ratio, expressed as the volume of hydrogen, measured
under normal temperature and pressure conditions, per volume of
liquid feed, is advantageously in the range 50 L/L to 2000 L/L. The
operating conditions in steps a) and b) may be identical or
different. Preferably, they are identical.
Step a): Hydrotreatment with a Catalyst in the Oxide Form
[0051] In step a) of the process of the invention, said hydrocarbon
feed is brought into contact, in the presence of hydrogen, with at
least a first catalyst comprising an alumina support, phosphorus
and an active phase formed by at least one metal from group VIB in
the oxide form and at least one metal from group VIII in the oxide
form, said first catalyst being prepared using a process comprising
at least one calcining step.
[0052] The catalyst used in step a) of the invention is composed of
an alumina support, phosphorus and an active phase formed by at
least one metal from group VIB in the oxide form and at least one
metal from group VIII in the oxide form.
[0053] In general, the total quantity of metal from group VIB and
metal from group VIII is more than 6% by weight, preferably in the
range 10% to 50% by weight of oxides of metals from groups VIB and
VIII with respect to the total catalyst weight.
[0054] The quantity of metal from group VIB is in the range 5% to
40% by weight, preferably in the range 8% to 35% by weight, and
more preferably in the range 10% to 30% by weight of oxide of
metal(s) from group VIB with respect to the total catalyst
weight.
[0055] The quantity of metal from group VIII is in the range 1% to
10% by weight, preferably in the range 1.5% to 9% by weight, and
more preferably in the range 2% to 8% by weight of oxide of metal
from group VIII with respect to the total catalyst weight.
[0056] The metal from group VIB present in the active phase of the
catalyst used in the hydrotreatment process of the invention is
preferably molybdenum.
[0057] The metal from group VIII present in the active phase of the
catalyst used in the hydrotreatment process of the invention is
preferably selected from cobalt, nickel and a mixture of these two
elements.
[0058] Preferably, the active phase of the catalyst used in step a)
is selected from the group formed by the following combination of
elements: nickel-molybdenum, cobalt-molybdenum and
nickel-cobalt-molybdenum.
[0059] The molar ratio of the metal from group VIII to the metal
from group VIB in the catalyst in the oxide form is preferably in
the range 0.1 to 0.8, preferably in the range 0.15 to 0.6, and more
preferably in the range 0.2 to 0.5.
[0060] Said catalyst of step a) also comprises phosphorus as a
dopant. The dopant is an element which is added which in itself
does not have any catalytic character, but which increases the
catalytic activity of the active phase.
[0061] The quantity of phosphorus in said catalyst for step a) is
preferably in the range 0.1% to 10% by weight of P.sub.2O.sub.5,
preferably in the range 0.2% to 8% by weight of P.sub.2O.sub.5,
more preferably in the range 0.3% to 8% by weight of
P.sub.2O.sub.5.
[0062] The molar ratio of phosphorus to metal from group VIB in the
catalyst for said step a) is 0.05 or more, preferably 0.07 or more,
more preferably in the range 0.08 to 0.5.
[0063] The catalyst used in step a) of the invention may
advantageously further contain at least one dopant selected from
boron and fluorine and a mixture of boron and fluorine.
[0064] When the hydrotreatment catalyst used in step a) contains
boron, the content is preferably in the range 0.1% to 10% by weight
of boron oxide, preferably in the range 0.2% to 7% by weight of
boron oxide, highly preferably in the range 0.2% to 5% by weight of
boron oxide.
[0065] When the hydrotreatment catalyst used in step a) contains
fluorine, the fluorine content is preferably in the range 0.1% to
10% by weight of fluorine, preferably in the range 0.2% to 7% by
weight of fluorine, highly preferably in the range 0.2% to 5% by
weight of fluorine.
[0066] The support is an alumina support, i.e. it contains alumina,
and optionally metals and/or dopant(s), which have been introduced
separately from the impregnations (for example introduced during
preparation (mixing, peptizing etc.) of the support or during its
shaping). The support is obtained after shaping (for example by
extrusion) and calcining, in general between 300.degree. C. and
600.degree. C.
[0067] Preferably, the support is constituted by alumina,
preferably extruded alumina. Preferably, the alumina is gamma
alumina; more preferably, said alumina support is constituted by
gamma alumina.
[0068] The pore volume of the amorphous support is generally in the
range 0.1 cm.sup.3/g to 1.5 cm.sup.3/g, preferably in the range 0.4
cm.sup.3/g to 1.1 cm.sup.3/g. The total pore volume is measured by
mercury porosimetry in accordance with ASTM standard D 4284-92 with
a wetting angle of 140.degree., as described in the work by
Rouquerol F.; Rouquerol J.; Singh K, "Adsorption by Powders &
Porous Solids: Principle, methodology and applications", Academic
Press, 1999, for example instrument from the firm
Micromeritics.TM., model Autopore III.TM..
[0069] The specific surface area of the amorphous support is
generally in the range 5 m.sup.2/g to 400 m.sup.2/g, preferably in
the range 10 m.sup.2/g to 350 m.sup.2/g, more preferably in the
range 40 m.sup.2/g to 350 m.sup.2/g. The specific surface area is
determined in the present invention by the BET method, which method
is described in the work which is cited above.
[0070] Said alumina support is advantageously in the powder form or
is shaped into beads, extrudates, pellets, or irregular and
non-spherical agglomerates the specific shape of which may be the
result of a crushing step. Highly advantageously, said support is
in the form of extrudates.
[0071] A catalyst in the oxide form used in step a) may be prepared
using any method which is well known to the skilled person.
[0072] The metals from group VIB and from group VIII of said
catalyst may advantageously be introduced into the catalyst at
various stages of the preparation and in a variety of manners. Said
metals from group VIB and from group VIII may advantageously be
introduced in part during shaping of said amorphous support or, as
is preferable, after said shaping.
[0073] In the case in which the metals from group VIB and from
group VIII are introduced in part during shaping of said alumina
support, they may be introduced in part only at the time of mixing
with an alumina gel selected as the matrix, the remainder of the
metals then being introduced subsequently. Preferably, when the
metals from group VIB and from group VIII are introduced in part at
the time of mixing, the proportion of metal from group VIB
introduced during this step is 20% or less of the total quantity of
metal from group VIB introduced onto the final catalyst and the
proportion of metal from group VIII introduced during this step is
50% or less of the total quantity of metal from group VIII
introduced onto the final catalyst.
[0074] In the case in which the metals from group VIB and from
group VIII are introduced at least in part and preferably in their
entirety after shaping said alumina support, the metals from group
VIB and from group VIII may advantageously be introduced onto the
alumina support by means of one or more excess solution
impregnations onto the alumina support or, as is preferable, by one
or more dry impregnations, preferably a single dry impregnation of
said alumina support, with the aid of aqueous or organic solutions
containing precursors of the metals. Dry impregnation consists of
bringing the support into contact with a solution containing at
least one precursor of said metal (metals) from group VIB and/or
from group VIII, the volume of which is equal to the pore volume of
the support to be impregnated. The solvent for the impregnation
solution may be water or an organic compound such as an alcohol.
Preferably, an aqueous solution is used as the impregnation
solution.
[0075] Highly preferably, the metals from group VIB and from group
VIII are introduced in their entirety after shaping said alumina
support, by dry impregnation of said support with the aid of an
aqueous impregnation solution containing precursor salts of the
metals. The metals from group VIB and from group VIII may also
advantageously be introduced by one or more impregnations of the
alumina support, using a solution containing precursor salts of the
metals. In the case in which the metals are introduced in a
plurality of impregnations of the corresponding precursor salts, an
intermediate step for drying the catalyst is generally carried out
at a temperature in the range 50.degree. C. to 180.degree. C.,
preferably in the range 60.degree. C. to 150.degree. C. and highly
preferably in the range 75.degree. C. to 130.degree. C.
[0076] Preferably, the metal from group VIB is introduced at the
same time as the metal from group VIII, irrespective of the mode of
introduction.
[0077] The molybdenum precursors which may be used are well known
to the skilled person. As an example, from among the molybdenum
sources, it is possible to use oxides and hydroxides, molybdic
acids and their salts, in particular ammonium salts such as
ammonium molybdate, ammonium heptamolybdate, phosphomolybdic acid
(H.sub.3PMo.sub.12O.sub.40), and their salts, and optionally
silicomolybdic acid (H.sub.4SiMo.sub.12O.sub.40) and its salts. The
molybdenum sources may also be any heteropolycompound of the
Keggin, lacunary Keggin, substituted Keggin, Dawson, Anderson or
Strandberg type, for example. Preferably, molybdenum trioxide and
heteropolycompounds of the Keggin, lacunary Keggin, substituted
Keggin and Strandberg type are used.
[0078] The cobalt precursors which may be used are advantageously
selected from oxides, hydroxides, hydroxycarbonates, carbonates and
nitrates, for example. Cobalt hydroxide and cobalt carbonate are
preferably used.
[0079] The nickel precursors which may be used are advantageously
selected from oxides, hydroxides, hydroxycarbonates, carbonates and
nitrates, for example. Nickel hydroxide and nickel hydroxycarbonate
are preferably used.
[0080] In the same manner, the phosphorus may advantageously be
introduced into the catalyst at various stages in the preparation
and in a variety of manners. Said phosphorus may advantageously be
introduced during shaping of said alumina support or, as is
preferable, after shaping it. It may, for example, be introduced
just before or just after peptizing the selected matrix such as,
for example and preferably, the aluminium oxyhydroxide (boehmite)
precursor of alumina. It may also advantageously be introduced
alone or as a mixture with at least one of the metals from group
VIB and VIII.
[0081] Said phosphorus is preferably introduced as a mixture with
the precursors of the metals from groups VIB and group VIII, in its
entirety or in part onto the shaped alumina support, preferably
alumina in the extruded form, by dry impregnation of said alumina
support using a solution containing precursors of the metals and
the phosphorus precursor.
[0082] The preferred source of phosphorus is orthophosphoric acid,
H.sub.3PO.sub.4, but salts and esters such as ammonium phosphates
are also suitable. The phosphorus may also be introduced at the
same time as the group VIB element(s) in the form of Keggin,
lacunary Keggin, substituted Keggin or Strandberg type
heteropolyanions.
[0083] The catalyst used in step a) of the invention may
advantageously further contain at least one dopant selected from
boron and fluorine and a mixture of boron and fluorine. This dopant
may be introduced in the same manner as that for the phosphorus at
various stages in the preparation and in a variety of manners. It
may be introduced at least in part during the preparation of the
support (including shaping). It may advantageously be introduced
alone or as a mixture with the phosphorus or at least one of the
precursors of the metals from groups VIB and VIII. It is preferably
introduced as a mixture with the precursors of the metals from
group VIB and from group VIII and phosphorus, in its entirety or in
part onto the shaped alumina support, preferably alumina in the
extruded form, by dry impregnation of said alumina support using a
solution containing precursors of the metals, the phosphorus
precursor and the precursor(s) of the dopant being selected from
boron and/or fluorine.
[0084] The source of boron may be boric acid, preferably orthoboric
acid H.sub.3B O.sub.3, ammonium biborate or pentaborate, boron
oxide, or boric esters. The boron may, for example, be introduced
by means of a solution of boric acid in a water/alcohol mixture or
in a water/ethanolamine mixture.
[0085] The sources of fluorine which may be used are well known to
the skilled person. As an example, the fluoride anions may be
introduced in the form of hydrofluoric acid or its salts. These
salts are formed with alkali metals, ammonium or an organic
compound. In this latter case, the salt is advantageously formed in
the reaction mixture by reaction between the organic compound and
hydrofluoric acid. The fluorine may, for example, be introduced by
impregnation of an aqueous solution of hydrofluoric acid or
ammonium fluoride, or indeed ammonium bifluoride.
[0086] In a preferred mode, the process for the preparation of the
catalyst of step a) of the process of the invention comprises the
following steps:
[0087] a') impregnating a solution containing at least one
precursor of a metal from group VIB, at least one precursor of a
metal from group VIII, phosphorus, optionally another dopant
selected from boron and/or fluorine, onto an alumina support;
[0088] a'') optionally, drying the impregnated support obtained
from step a');
[0089] a''') calcining the impregnated and optionally dried support
so as to transform the precursors of the metals from group VIB and
from group VIII into oxides.
[0090] Impregnation step a') is carried out in accordance with the
variations described above. Highly preferably, the metals from
group VIB and from group VIII, the phosphorus and optional other
dopant selected from boron and/or fluorine are introduced in their
entirety after shaping said alumina support, by dry impregnation of
said support with the aid of an aqueous impregnation solution
containing precursor salts of the metals, phosphorus and optional
dopant selected from boron and/or fluorine.
[0091] The drying of step a'') is generally carried out at a
temperature in the range 50.degree. C. to 180.degree. C.,
preferably in the range 60.degree. C. to 150.degree. C. and highly
preferably in the range 75.degree. C. to 130.degree. C. Drying is
generally carried out for a period in the range 1 to 24 hours,
preferably in the range 1 to 20 hours. Drying is carried out in
air, or under an inert atmosphere (for example nitrogen).
[0092] The calcining of step a''') is generally carried out at a
temperature in the range 250.degree. C. to 900.degree. C.,
preferably in the range 350.degree. C. to 750.degree. C. The
calcining period is generally in the range 0.5 hours to 16 hours,
preferably in the range 1 hour to 5 hours. It is generally carried
out in air. Calcining can be used to transform the precursors of
the metals from groups VIB and VIII into oxides.
[0093] Before using it, it is advantageous to transform the
catalyst in the oxide form (calcined) used in step a) of the
process of the invention into a sulphurized catalyst in order to
form its active species. This activation or sulphurization phase is
carried out using methods which are well known to the skilled
person, advantageously in a sulpho-reducing atmosphere in the
presence of hydrogen and hydrogen sulphide.
[0094] In a preferred variation, the catalyst obtained in step
a''') undergoes a sulphurization step. The sulphurization step is
advantageously carried out in an ex situ or in situ manner. The
sulphurizing agents are H.sub.2S gas or any other compound
containing sulphur used for activation of hydrocarbon feeds with a
view to sulphurizing the catalyst. Said compounds containing
sulphur are advantageously selected from alkyldisulphides such as,
for example, dimethyldisulphide (DMDS), alkylsulphides such as, for
example dimethyl sulphide, n-butylmercaptan, polysulphide compounds
of the tertiononoylpolysulphide type, or any other compound which
is known to the skilled person and can result in good
sulphurization of the catalyst. Preferably, the catalyst is
sulphurized in situ in the presence of a sulphurizing agent and a
hydrocarbon feed. Highly preferably, the catalyst is sulphurized in
situ in the presence of a hydrocarbon feed supplemented with
dimethyldisulphide.
Step b): Hydrotreatment with an Additive-Containing Catalyst
[0095] In accordance with step b) of the process of the invention,
the effluent obtained from step a) is brought into contact, in the
presence of hydrogen, with at least a second catalyst comprising an
alumina support, phosphorus, an active phase formed by at least one
metal from group VIB and at least one metal from group VIII and at
least one organic compound containing oxygen and/or nitrogen, said
second catalyst being prepared in accordance with a process
comprising the following steps:
[0096] i) bringing at least one component of a metal from group
VIB, at least one component of a metal from group VIII, phosphorus
and at least one organic compound containing oxygen and/or nitrogen
into contact with the support, in order to obtain a catalyst
precursor;
[0097] ii) drying said catalyst precursor obtained from step i) at
a temperature of less than 200.degree. C., without subsequent
calcining thereof.
[0098] The catalyst used in step b) of the invention is composed of
an alumina support, phosphorus, an active phase formed by at least
one metal from group VIB and at least one metal from group VIII,
and an organic compound containing oxygen or nitrogen. The catalyst
used in step b) is a catalyst termed an additive-containing
catalyst. During its preparation, it does not undergo calcining,
i.e. its active phase comprises metals from groups VIB and VIII
which have not been transformed into the oxide form.
[0099] The total quantity of metal from group VIII and metal from
group VIB as well as the molar ratio of the metal from group VIII
to the metal from group VIB of the catalyst of step b) are in the
same ranges as those described for the catalyst of step a).
[0100] The metal from group VIB present in the active phase of the
catalyst used in step b) of the invention is preferably
molybdenum.
[0101] The metal from group VIII present in the active phase of the
catalyst used in step b) of the invention is preferably selected
from cobalt, nickel and a mixture of these two elements.
[0102] Preferably, the active phase of the catalyst used in step b)
is selected from the group formed by the following combinations of
elements: nickel-molybdenum, cobalt-molybdenum and
nickel-cobalt-molybdenum.
[0103] The additive-containing catalyst used in step b) also
comprises phosphorus as the dopant. The phosphorus content of the
catalyst of step b) as well as the molar ratio of phosphorus to the
metal from group VIB of the catalyst of step b) are in the same
ranges as those described for the catalyst of step a).
[0104] The catalyst used in step b) of the invention may
advantageously further contain at least one other dopant selected
from boron and/or fluorine. When the catalyst used in step b)
contains boron and/or fluorine, the quantities of boron and/or
fluorine are in the same ranges as those described for the catalyst
of step a).
[0105] The alumina support for said catalyst used in step b) was
described in the section pertaining to step a). The support for the
additive-containing catalyst of step b) may be identical to or
different from the support of the catalyst used in step a).
[0106] Preferably, the support for said catalyst used in step b) is
constituted by alumina, preferably extruded alumina. Preferably,
the alumina is gamma alumina, and said alumina support is
preferably constituted by gamma alumina.
[0107] The catalyst used in step b) further contains an organic
compound containing oxygen and/or nitrogen. This compound is an
organic compound containing more than 2 carbon atoms and at least
one oxygen and/or nitrogen atom.
[0108] The organic compound containing oxygen may be one or more
compounds selected from a carboxylic acid, an alcohol, an aldehyde
or an ester. By way of example, the organic compound containing
oxygen may be one or more compounds selected from the group
constituted by ethylene glycol, glycerol, polyethylene glycol (with
a molecular weight of 200 to 1500), acetophenone, 2,4-pentanedione,
pentanole, acetic acid, maleic acid, oxalic acid, tartaric acid,
formic acid, citric acid and C1-C4 dialkyl succinate. The dialkyl
succinate used is preferably included in the group composed of
dimethyl succinate, diethyl succinate, dipropyl succinate and
dibutyl succinate. Preferably, the C1-C4 dialkyl succinate used is
dimethyl succinate or diethyl succinate. Highly preferably, the
C1-C4 dialkyl succinate used is dimethyl succinate. At least one
C1-C4 dialkyl succinate is used, preferably one alone, and
preferably dimethyl succinate.
[0109] The organic compound containing nitrogen may be selected
from an amine. By way of example, the organic compound containing
nitrogen may be ethylene diamine or tetramethylurea.
[0110] The organic compound containing oxygen and nitrogen may be
selected from an aminocarboxylic acid, an aminoalcohol, a nitrile
or an amide. By way of example, the organic compound containing
oxygen and nitrogen may be aminotriacetic acid,
1,2-cyclohexanediaminetetraacetic acid, mono-ethanolamine,
acetonitrile, N-methylpyrrolidone, dimethylformamide or EDTA.
[0111] Preferably, the organic compound contains oxygen.
Particularly preferably, the organic compound comprises at least
the combination of C1-C4 dialkyl succinate, in particular dimethyl,
and acetic acid. In accordance with another particularly preferred
variation, the organic compound comprises at least citric acid.
[0112] The catalyst used in step b) is prepared in accordance with
a process comprising the following steps:
[0113] i) bringing at least one component of a metal from group
VIB, at least one component of a metal from group VIII, phosphorus
and at least one organic compound containing oxygen and/or nitrogen
into contact with the support, in order to obtain a catalyst
precursor;
[0114] ii) drying said catalyst precursor obtained from step i) at
a temperature of less than 200.degree. C., without subsequent
calcining thereof.
[0115] Contact step i) can be implemented in a number of
manners.
[0116] In accordance with the first implementation of step i) of
the process for the preparation of the catalyst used in step b),
said components of the metals from group VIB and group VIII,
phosphorus and that of said organic compound are deposited on said
support by at least one co-impregnation step, preferably by dry
impregnation. In accordance with this implementation, also known as
"co-impregnation", said components of the metals from group VIB and
group VIII, phosphorus and the organic compound are simultaneously
introduced into said support. Said first embodiment of step i)
comprises carrying out one or more co-impregnation steps, each
co-impregnation step preferably being followed by a drying step as
described in step i'') below.
[0117] In accordance with the second embodiment of step i) of the
process for the preparation of the catalyst used in step b), at
least one catalytic precursor comprising at least one metal from
group VIII, at least one metal from group VIB, said phosphorus and
at least said alumina support are brought into contact with at
least one organic compound containing oxygen and/or nitrogen. In
accordance with the invention, said second embodiment is a
preparation known as "post-impregnation". In accordance with this
variation, the catalyst precursor is prepared by depositing at
least one component of a metal from group VIB, at least one
component of a metal from group VIII and phosphorus on said support
using any method known to the skilled person, preferably by dry
impregnation, excess impregnation or by deposition-precipitation
using methods which are well known to the skilled person. The
components of the metals from groups VIB and VIII and phosphorus
may be deposited by one or more impregnations, preferably followed
by a drying step as described in step i'') below.
[0118] In accordance with a particularly preferred variation, the
contact of step i) is carried out in accordance with the second
embodiment of step i), i.e. by post-impregnation. In a particularly
preferred variation, the catalyst used in step b) is prepared in
accordance with the preparation process described in US
2013/008829. More precisely, step i) of the process for the
preparation of the catalyst of step b) may comprise the following
steps in succession which will be described in more detail
below:
[0119] i') impregnating an alumina support with at least one
solution containing at least one metal from group VIB, at least one
metal from group VIII and said phosphorus in order to obtain an
impregnated support;
[0120] i'') drying the impregnated support obtained in step i') at
a temperature of less than 180.degree. C. without subsequent
calcining, in order to obtain a dried impregnated support;
[0121] i''') impregnating the dried impregnated support obtained in
step i'') with an impregnation solution comprising at least one
organic compound containing oxygen and/or nitrogen in order to
obtain an impregnated catalytic precursor;
[0122] i'''') allowing the impregnated catalytic precursor obtained
in step i''') to mature, in order to obtain said catalyst
precursor.
[0123] In step i'), the metals from group VIB and from group VIII
may advantageously be introduced onto the alumina support by one or
more excess solution impregnations, or preferably by one or more
dry impregnations and more preferably by a dry impregnation of said
alumina support, using an aqueous or organic solution containing
precursors of the metals. The impregnation step may be carried out
in the same manner as that described for the preparation of the
catalyst in the oxide form described in step a). The precursors of
the metal from group VIB and from group VIII are those described
for step a). Said phosphorus and the optional other dopant selected
from boron and/or fluorine may be introduced in the manner
described in step a). The phosphorus, boron and fluorine precursors
are those described in step a).
[0124] Introduction of the metals from group VIB and from group
VIII and phosphorus onto the alumina support is then followed by a
step i'') for drying, during which the solvent (which is generally
water) is eliminated, at a temperature in the range 50.degree. C.
to 180.degree. C., preferably in the range 60.degree. C. to
150.degree. C. or in the range 65.degree. C. to 145.degree. C., and
highly preferably in the range 70.degree. C. to 140.degree. C. or
in the range 75.degree. C. to 130.degree. C. The step for drying
the dried impregnated support obtained thereby is never followed by
a step for calcining in air at a temperature of more than
200.degree. C.
[0125] Preferably, in step i'), said impregnated support is
obtained by dry impregnation of a solution comprising precursors of
metals from group VIB and from group VIII, and phosphorus onto an
alumina support which has been calcined and shaped, followed by
drying at a temperature of less than 180.degree. C., preferably in
the range 50.degree. C. to 180.degree. C., preferably in the range
60.degree. C. to 150.degree. C. and highly preferably in the range
75.degree. C. to 130.degree. C. A dried impregnated support is thus
obtained at the end of step i'').
[0126] In accordance with step i'''), said dried impregnated
support is impregnated with an impregnation solution comprising at
least one organic compound containing oxygen and/or nitrogen,
preferably C1-C4 dialkyl succinate (and in particular dimethyl
succinate) and acetic acid. In another variation, the impregnation
solution of step i''') preferably comprises citric acid. The
impregnation solution comprising at least said organic compound is
preferably an aqueous solution.
[0127] The molar ratio of the organic compound(s) containing oxygen
and/or nitrogen over the impregnated element(s) from group VIB of
the catalytic precursor engaged on the catalyst is in the range
0.05 to 2 mol/mol, preferably in the range 0.1 to 1.8 mol/mol,
preferably in the range 0.15 to 1.5 mol/mol before the drying of
step ii). When the organic component is a mixture of C1-C4 dialkyl
succinate (and in particular dimethyl succinate) and acetic acid,
said components are advantageously introduced into the impregnation
solution of step i''') of the process of the invention in a
quantity corresponding to: [0128] a molar ratio of dialkyl
succinate (for example dimethyl) to impregnated element(s) from
group VIB of the catalytic precursor in the range 0.05 to 2
mol/mol, preferably in the range 0.1 to 1.8 mol/mol, more
preferably in the range 0.15 to 1.5 mol/mol; [0129] a molar ratio
of acetic acid to impregnated element(s) from group VIB of the
catalytic precursor in the range 0.1 to 5 mol/mol, preferably in
the range 0.5 to 4 mol/mol, more preferably in the range 1.3 to 3
mol/mol and highly preferably in the range 1.5 to 2.5 mol/mol.
[0130] Said organic compound(s) may advantageously be deposited in
one or more steps, either by slurry impregnation or by excess
impregnation or by dry impregnation, or by any other means which is
known to the skilled person.
[0131] In accordance with step i'''), the organic compound
containing oxygen or nitrogen is introduced onto the dried
impregnated support by at least one impregnation step, preferably
by a single impregnation step, and particularly preferably by a
single dry impregnation step.
[0132] In accordance with step i'''') of the preparation process of
the invention, the impregnated catalytic precursor obtained from
step i''') undergoes a maturation step. It is advantageously
carried out at atmospheric pressure and at a temperature in the
range 17.degree. C. to 50.degree. C., and generally a maturation
period in the range ten minutes to forty-eight hours, preferably in
the range thirty minutes to five hours is sufficient. Longer times
are not excluded. A catalyst precursor is thus obtained at the end
of step i'''').
[0133] In accordance with step ii) of the preparation process of
the invention, the catalyst precursor obtained from step i)
undergoes a drying step at a temperature below 200.degree. C.,
without subsequently calcining it.
[0134] The drying step ii) of the process of the invention is
advantageously carried out using any technique which is known to
the skilled person. It is advantageously carried out at atmospheric
pressure or under reduced pressure. Preferably, this step is
carried out at atmospheric pressure.
[0135] This step ii) is advantageously carried out at a temperature
in the range 50.degree. C. to less than 200.degree. C., preferably
in the range 60.degree. C. to 180.degree. C. and highly preferably
in the range 80.degree. C. to 160.degree. C.
[0136] Step ii) is advantageously carried out in a flushed bed
using air or any other hot gas. Preferably, when drying is carried
out in a fixed bed, the gas used is either air or an inert gas such
as argon or nitrogen. Highly preferably, drying is carried out in a
flushed bed in the presence of nitrogen.
[0137] Preferably, this step lasts in the range 30 minutes to 4
hours, preferably in the range 1 hour to 3 hours.
[0138] At the end of step ii) of the process of the invention, a
dry catalyst is obtained which is also known as the
"additive-containing catalyst", which does not undergo any
subsequent calcining step in air, for example at a temperature of
more than 200.degree. C.
[0139] Before using it, it is advantageous to transform the
additive-containing catalyst used in step b) into a sulphurized
catalyst in order to form its active species. This activation or
sulphurization phase is carried out using methods which are well
known to the skilled person, and advantageously in a
sulpho-reductive atmosphere in the presence of hydrogen and
hydrogen sulphide.
[0140] At the end of step ii) of the process of the invention, said
dried additive-containing catalyst obtained thus advantageously
undergoes a sulphurizing step iii), without an intermediate
calcining step.
[0141] Said additive-containing catalyst is advantageously
sulphurized ex situ or in situ. The same sulphurization agents as
those described for the catalyst in the oxide form in step a) may
be used.
[0142] When sulphurization is carried out in situ, sulphurization
of the catalyst of step b) is advantageously carried out at the
same time as sulphurization of the catalyst of step a).
[0143] Without further elaboration, it is believed that one skilled
in the art can, using the preceding description, utilize the
present invention to its fullest extent. The preceding preferred
specific embodiments are, therefore, to be construed as merely
illustrative, and not limitative of the remainder of the disclosure
in any way whatsoever.
[0144] In the foregoing and in the examples, all temperatures are
set forth uncorrected in degrees Celsius and, all parts and
percentages are by weight, unless otherwise indicated.
[0145] The entire disclosures of all applications, patents and
publications, cited herein and of corresponding French application
No. 13/61.801, filed Nov. 28, 2013 are incorporated by reference
herein.
EXAMPLES
[0146] The following examples demonstrate that a hydrotreatment
process in accordance with the invention using a "catalyst in the
oxide form/additive-containing catalyst" concatenation has improved
activity and improved stability compared with a process using only
additive-containing catalysts.
Preparation of Catalysts A, B, C and D:
[0147] The following 4 catalysts were prepared: [0148] catalyst A:
calcined NiMoP/alumina catalyst [0149] catalyst B: calcined
CoMoP/alumina catalyst [0150] catalyst C: NiMoP/alumina catalyst
supplemented with acetic acid and dimethyl succinate
(post-impregnation) [0151] catalyst D: CoMoP/alumina catalyst
supplement with citric acid (co-impregnation)
Preparation of Support
[0152] A matrix composed of an ultrafine tabular boehmite or
alumina gel was used, sold by Condea Chemie GmbH. This gel was
mixed with an aqueous solution containing 66% nitric acid (7% by
weight of acid per gram of dry gel) then mixed for 15 minutes. At
the end of this mixing, the paste obtained was passed through a die
having cylindrical orifices with a diameter equal to 1.6 mm. The
extrudates were then dried overnight at 120.degree. C. and calcined
at 600.degree. C. for 2 hours in moist air containing 50 g of water
per kg of dry air. Thus, extrudates of the support were obtained
which had a specific surface area of 300 m.sup.2/g. X ray
diffraction analysis revealed that the support is solely composed
of low crystallinity cubic gamma alumina.
Catalyst A: Calcined NiMoP/Alumina Catalyst
[0153] In the case of catalyst A based on nickel, the nickel,
molybdenum and phosphorus were added to the alumina support
described above which was in the form of extrudates. The
impregnation solution was prepared by hot dissolving the molybdenum
oxide and nickel hydroxycarbonate in the phosphoric acid solution
in aqueous solution with the aim of producing an approximately
4/22/5 formulation, expressed as the % by weight of oxides of
nickel and molybdenum and as the % by weight of phosphoric
anhydride with respect to the quantity of dry matter in the final
catalyst. After dry impregnation, the extrudates were allowed to
mature in a water-saturated atmosphere for 8 h, then they were
dried overnight at 90.degree. C. Calcining at 450.degree. C. for 2
hours resulted in catalyst A.
[0154] The final composition of catalyst A, expressed in the oxide
form, was then as follows: MoO.sub.3=22.0.+-.0.2 (% by weight),
NiO=4.1.+-.0.1 (% by weight) and P.sub.2O.sub.5=5.0.+-.0.1 (% by
weight).
Catalyst B: Calcined CoMoP
[0155] In the case of catalyst B based on cobalt, the cobalt,
molybdenum and phosphorus were added to the alumina support
described above which was in the form of extrudates. The
impregnation solution was prepared by hot dissolving the molybdenum
oxide and cobalt carbonate in the phosphoric acid solution in
aqueous solution with the aim of producing an approximately 4/22/5
formulation, expressed as the % by weight of oxides of cobalt and
molybdenum and as the % by weight of phosphoric anhydride with
respect to the quantity of dry matter in the final catalyst. After
dry impregnation, the extrudates were allowed to mature in a
water-saturated atmosphere for 8 h, then they were dried overnight
at 90.degree. C. Calcining at 450.degree. C. for 2 hours resulted
in catalyst B.
[0156] The final composition of catalyst B, expressed in the oxide
form, was then as follows: MoO.sub.3=22.0.+-.0.2 (% by weight),
CoO=4.1.+-.0.1 (% by weight) and P.sub.2O.sub.5=5.0.+-.0.1 (% by
weight).
Catalyst C: NiMoP/Alumina Catalyst Supplemented with Acetic Acid
and Dimethyl Succinate (DMSU)
[0157] In the case of catalyst C based on nickel, the nickel,
molybdenum and phosphorus were added to the alumina support
described above in the form of extrudates. The impregnation
solution was prepared by hot dissolving molybdenum oxide and nickel
hydroxycarbonate in the solution of phosphoric acid in aqueous
solution with the aim of obtaining an approximately 5/25/6
formulation expressed as the % by weight of oxides of nickel and
molybdenum and as the % by weight of phosphoric anhydride with
respect to the quantity of dry matter of the final catalyst. After
dry impregnation, the extrudates were allowed to mature in a
water-saturated atmosphere for 8 h, then they were dried overnight
at 90.degree. C. The dried impregnated support for catalyst C was
then supplemented by dry impregnation of a solution containing a
mixture of dimethyl succinate (DMSU) and acetic acid (75% pure).
The molar ratios were as follows: DMSU/Mo=0.85 mol/mol, DMSU/acetic
acid=0.5 mol/mol. Next, the catalyst underwent a maturing step for
3 h at 20.degree. C. in air, followed by drying in a flushed bed
type oven at 120.degree. C. for 3 h.
[0158] The final composition of catalyst C, expressed in the oxide
form, was thus as follows: MoO.sub.3=25.1.+-.0.2 (% by weight),
NiO=5.1.+-.0.1 (% by weight) and P.sub.2O.sub.5=6.0.+-.0.1 (% by
weight).
Catalyst D: CoMoP/Alumina Catalyst Supplemented with Citric
Acid
[0159] In the case of catalyst D based on cobalt, the cobalt,
molybdenum and phosphorus were added to the alumina support
described above in the form of extrudates. The impregnation
solution was prepared by hot dissolving molybdenum oxide and cobalt
hydroxide and citric acid in the solution of phosphoric acid in
aqueous solution with the aim of obtaining an approximately 4/22/5
formulation, expressed as the % by weight of oxides of cobalt and
molybdenum and as the % by weight of phosphoric anhydride with
respect to the quantity of dry matter of the final catalyst. The
quantity of citric acid, expressed as the molar ratio with respect
to molybdenum, was: citric acid/Mo=0.4 mol/mol. After dry
impregnation, the extrudates were allowed to mature in a
water-saturated atmosphere for 8 h, then they were dried overnight
at 90.degree. C. then dried in a flushed bed type oven at
140.degree. C. for 3 h.
[0160] The final composition of catalyst D, expressed in the oxide
form, was thus as follows: MoO.sub.3=22.4.+-.0.2 (% by weight),
CoO=4.1.+-.0.1 (% by weight) and P.sub.2O.sub.5=5.0.+-.0.1 (% by
weight).
Evaluation of Various Concatenations of Catalysts A, B, C and D in
the Hydrotreatment of a Straight-Run Diesel/LCO Mixture
[0161] The feed used was a mixture of 70% by volume of diesel
obtained from atmospheric distillation (straight-run) and 30% by
volume of coker gas with a WAT of 285.degree. C. The
characteristics of the feed were as follows: density (at 15.degree.
C.) 0.8486, sulphur 1.06% by weight, nitrogen 410 ppm, basic
nitrogen 200 ppm, aromatics (UV) 29% by weight. [0162] Simulated
distillation:
TABLE-US-00001 [0162] IP: 150.degree. C. 5%: 200.degree. C. 10%:
220.degree. C. 50%: 283.degree. C. 70%: 307.degree. C. 90%:
337.degree. C.
[0163] The test was carried out in an isothermal pilot reactor with
a fixed flushed bed, with the fluids moving from bottom to top. The
reactor comprised two catalytic zones for evaluating various
concatenations of the catalysts A, B, C and D. The feed passed
initially over the first zone charged with the first catalyst, then
the second zone charged with the second catalyst.
[0164] In accordance with Example 1 (not in accordance with the
invention), the entirety of the two catalytic zones (100% of the
volume) contained additive-containing catalyst (catalyst C).
[0165] In accordance with Examples 2 and 3 (in accordance with the
invention), the first zone was charged with a calcined catalyst
(catalysts A or B: 30% of the volume), then the second with an
additive-containing catalyst (catalyst C: 70% of the volume).
[0166] In accordance with Example 4 (not in accordance with the
invention), the two zones were charged with an additive-containing
catalyst (catalyst D: 30% of the volume, then catalyst C: 70% of
the volume).
[0167] In accordance with Example 5 (not in accordance with the
invention), the first zone was charged with an additive-containing
catalyst (catalyst C: 70% of the volume), then the second with a
calcined catalyst (catalyst A: 30% of the volume).
[0168] After in situ sulphurization at 350.degree. C. in the unit
pressurized with diesel to which 2% by weight of dimethyldisulphide
had been added, the hydrodesulphurization test was carried out
under the following operating conditions: a total pressure of 5 MPa
(50 bar), a H.sub.2/feed ratio of 380 L/L and a HSV of 1.5
h.sup.-1.
[0169] The temperature was adjusted so as to obtain a sulphur
content of 10 ppm at the reactor outlet. The following table shows
the temperature necessary to obtain a sulphur content of 10 ppm for
the various concatenations of the catalysts A, B, C and D. A high
catalytic activity is expressed by a low temperature T1. A high
stability is expressed by a low temperature T2 after an operating
period (in this case 1000 hours).
[0170] The results clearly show that the "catalyst in the oxide
form/additive-containing catalyst" concatenation (Examples 2 and 3)
can be used to obtain a catalytic activity which is higher and a
higher stability than a concatenation of "additive-containing
catalysts" alone (Examples 1 and 4) or an "additive-containing
catalyst/catalyst in the oxide form" concatenation (Example 5).
TABLE-US-00002 TABLE temperature required to obtain a 10 ppm
content at the reactor outlet Catalyst charged into the reactor
Example (first zone/second zone) T1* T2** 1, 100% vol catalyst C
(additive- 345.degree. C. 348.degree. C. comparative containing
NiMoP) 2, 30% vol catalyst A (calcined 342.degree. C. 343.degree.
C. in accordance NiMoP) + 70% vol catalyst C with the
(additive-containing NiMoP) invention 3, 30% vol catalyst B
(calcined 343.degree. C. 345.degree. C. in accordance CoMoP) + 70%
vol catalyst C with the (additive-containing NiMoP) invention 4,
30% vol catalyst D (additive- 348.degree. C. 351.degree. C.
comparative containing CoMoP) + 70% vol catalyst C
(additive-containing NiMoP) 5, 70% vol catalyst C (additive-
352.degree. C. 357.degree. C. comparative containing NiMoP) + 30%
vol catalyst B (calcined NiMoP) *T1: temperature after 300 h
operation **T2: temperature after 1000 h operation
[0171] In the case of Examples 2, 3 and 4, the values for
hydrodenitrogenation (HDN) as a % of the first zone were as
follows; the conditions were as mentioned above: [0172] catalyst A
(calcined NiMoP): HDN (%)=70% the residual nitrogen content (total)
was of the order of 150 ppm, mainly in the form of non-basic
carbazole species [0173] catalyst B (calcined CoMoP): HDN (%)=67%
[0174] catalyst C (NiMoP supplemented with DMSU/acetic acid): HDN
(%)=63% [0175] catalyst D (CoMoP supplemented with citric acid):
HDN (%)=58%.
[0176] It will be observed that the calcined catalysts (catalysts A
and B) can be used to carry out more intense HDN than an
additive-containing catalyst (catalysts C and D).
[0177] The preceding examples can be repeated with similar success
by substituting the generically or specifically described reactants
and/or operating conditions of this invention for those used in the
preceding examples.
[0178] From the foregoing description, one skilled in the art can
easily ascertain the essential characteristics of this invention
and, without departing from the spirit and scope thereof, can make
various changes and modifications of the invention to adapt it to
various usages and conditions.
* * * * *