U.S. patent application number 10/036349 was filed with the patent office on 2002-07-25 for extruded catalyst based on silica/alumina gel, and process for preparing it.
Invention is credited to Bellussi, Giuseppe, Peratello, Stefano, Perego, Carlo.
Application Number | 20020099250 10/036349 |
Document ID | / |
Family ID | 11361275 |
Filed Date | 2002-07-25 |
United States Patent
Application |
20020099250 |
Kind Code |
A1 |
Peratello, Stefano ; et
al. |
July 25, 2002 |
Extruded catalyst based on silica/alumina gel, and process for
preparing it
Abstract
The preparation is disclosed of an extruded catalyst based on a
silica/alumina gel, which catalyst is particularly active in
acid-catalyzed reactions, such as the oligomerization of light
olefins, e.g., propylene.
Inventors: |
Peratello, Stefano; (Nova
Milanese, IT) ; Perego, Carlo; (Carnate, IT) ;
Bellussi, Giuseppe; (Piacenza, IT) |
Correspondence
Address: |
George P. Hoare, Jr.
Shea & Gould
1251 Avenue of the Americas
New York
NY
10020-1193
US
|
Family ID: |
11361275 |
Appl. No.: |
10/036349 |
Filed: |
November 9, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10036349 |
Nov 9, 2001 |
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08269647 |
Jun 30, 1994 |
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08269647 |
Jun 30, 1994 |
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07985552 |
Dec 3, 1992 |
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Current U.S.
Class: |
585/533 ;
502/263; 585/532 |
Current CPC
Class: |
B01J 21/12 20130101;
B01J 37/0009 20130101; C07C 2521/12 20130101; C07C 2/10 20130101;
B01J 35/1042 20130101; C07C 2521/02 20130101; B01J 35/023 20130101;
B01J 35/1038 20130101 |
Class at
Publication: |
585/533 ;
502/263; 585/532 |
International
Class: |
B01J 021/12; C07C
002/10; C07C 002/12 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 6, 1991 |
IT |
MI91 A 003276 |
Claims
1. Catalyst consisting of: an inert binding agent, and a
catalytically active portion, constituted by a silica/alumina gel,
amorphous at X rays, with SiO.sub.2/AL.sub.2O.sub.3 being in a
molar ratio comprised within the range of from 30:1 to 500:1,
having a total pore volume comprised within the range of from 0.3
to 0.6 mL/g, and substantially free from pores having a Longer
average diameter than 30 Angstrom, characterized in that: the inert
binding agent is constituted by alumina grades belonging to the
class of bohemite or of pseudobohemite.
2. Catalyst according to claim 1, characterized in that bohemite or
pseudobohemite have an average diameter shorter than 50 microns,
and are present in a ratio to silica/alumina gel comprised within
the range of from 0.2 to 2.5 by weight.
3. Process for preparing the catalyst according to claims from 1 to
2, characterized in that the active portion is mixed with the inert
phase, in the presence of a thickener containing a mineral or
organic acid in an amount comprised within the range of from 0.5 to
8 g of acid per 100 g of inert binding agent, until a homogeneous
paste is obtained which is subsequently extruded, yielding
cylindrical bodies of catalyst which are eventually submitted to:
ageing at a temperature comprised within the range of from 10 to
40.degree. C.; drying at a temperature comprised within the range
of from 100 to 120.degree. C.; calcination in air at a temperature
comprised within the range of from 500 to 600.degree. C.
4. Use of the catalyst according to claims from 1 to 2 in
acid-catalyzed reaction.
5. Use of the catalyst according to claims from 1 to 2 in the
oligomerization of light olefins.
6. Use of the catalyst according to claims from 1 to 2 in propylene
oligomerization.
Description
[0001] The present invention relates to a catalyst in extruded
form, based on silica/alumina gel, and to the process for preparing
it. The invention also relates to the use of such a catalyst in
olefin oligomerization processes.
[0002] Some silica/alumina gels, of amorphous character, displaying
catalytic activity, are known in the art. So, e.g., European patent
application published with publication No. 160,145 discloses a
process of alkylation of aromatic hydrocarbons which uses a
catalyst consisting of a silica/alumina gel, of amorphous
character, with pore diameter typically comprised within the range
of from 50 to 500 Angstrom, and with a ratio of silica to alumina
typically comprised within the range of from 1:1 to 10:1. M. R. S.
Manton and J. Davidtz in Journal of Catalysis, 60, 156-166 (1979)
describe a process for the synthesis for amorphous silica/alumina
catalysts, having a controlled pore diameter. Tipically, these
catalysts display pores with diameter comprised within the range of
from 3.7 to 15 nm.
[0003] European patent application No. 340,868 discloses a
silica/alumina gel, amorphous at X rays, having a molar ratio of
SiO.sub.2/AL.sub.2O.sub- .3 of from 30:1 to 500:1, with a specific
surface area comprised within the range of from 500 to 1000
m.sup.2/g, a total pore volume of from 0.3 to 0.6 mL/g, and
substantially free from pores with Larger diameter than 30
Angstrom.
[0004] However, the problem exists of rendering industrially
useable the silica/alumina gel disclosed in the above said patent
application by endowing it with adequate properties of mechanical
strength, without endangering the high catalytic performance
thereof.
[0005] Those skilled in the art are aware of the possible
procedures for preparing extruded bodies having high enough
mechanical strength values, with their catalytic performace being
the same. Thus, for example, the catalyst can be ground, so as to
obtain powders consisting of particles with an average size
comprised within the range of from 5 to 50 microns, and
subsequently blending them with a thickener, for example, stearine,
glycerol, methylcellulose.
[0006] According to another route of preparation of the extruded
catalyst, the catalyst is ground and then is suspended, with
vigourous stirring, in an aqueous solution of a soluble aluminum
salt. The addition of a base makes it possible aluminum hydroxide
to be precipitated, with the catalyst particles getting embedded
inside said precipitate particles. A further method consists in
mixing silica/alumina gel powders with a second powder selected
from metal oxides in the presence of a thickener, for example,
stearine, glycerol, methylcellulose.
[0007] All of the techniques cited hereinabove should make it
possible extrudates to be obtained, which are endowed with such a
high mechanical strength as to enable them to be used at an
industrial level, with the catalytic properties of silica/alumina
gel remaining unchanged.
[0008] It has been found now that one of the above said techniques
Leads to catalysts showing the necessary mechanical strength, but
which, surprisingly, are more active in catalysing the usual
petrochemical acid-catalysed reactions, such as alkylation,
isomerization and oligomerization.
[0009] In accordance therewith, according to a first aspect
thereof, the present invention relates to a catalyst consisting
of:
[0010] an inert binding agent, and
[0011] a catalytically active portion, constituted by a
silica/alumina gel, amorphous at X rays, with
SiO.sub.2/AL.sub.2O.sub.3 being in a molar ratio comprised within
the range of from 30:1 to 500:1, having a total pore volume
comprised within the range of from 0.3 to 0.6 ml/g, and
substantially free from pores having a longer average diameter than
30 Angstrom, characterized in that:
[0012] the inert binding agent is constituted by alumina grades
belonging to the class of bohemite or of pseudobohemite.
[0013] The aluminas used in the present invention as binding agents
in order to extrude the silica/alumina gel have the general
formula
A LO--OH.
[0014] In the preferred form of practical embodiment of the present
invention, bohemite or pseudobohemite have a shorter average
diameter than 50 microns, and are present in a ratio to
silica/alumina gel comprised within the range of from 0.2 to 2.5 by
weight.
[0015] The catalyst according to the present invention is suitably
prepared by means of a first mechanical mixing of the active
phase,(i.e., of silica/alumina gel ground until a powder having a
shorter average diameter than 50 microns, with the inert binding
agent belonging to the class of bohemites or pseudobohemites, or
mixtures thereof.
[0016] The mixing of the active phase with the inert binding agent
is carried out in the presence of a Large enough amount of
thickener as to produce a paste having the desired viscosity. The
mixing in continued until a homogeneous phase is formed. The
thickener may be water, an aqueous solution of methylcellulose,
stearine, glycerol and so forth. The thickener contains a mineral
or organic acid in an amount comprised within the range of from 0.5
to 8 grams of acid per 100 g of inert binding agent. According to
another form of practical embodiment, the acid is added to the
paste and the resulting mixture is homogenized.
[0017] The resulting paste is then extruded and cylindrical bodies
of catalyst are obtained, the dimensions of which may be varied as
a function of the application requirements.
[0018] The extrudate is subsequently submitted to ageing at a
temperature of from 10 to 40.degree. C., and then to drying at
100-120.degree. C.
[0019] The end step consists of the calcination in air at a
temperature comprised within the range of from 500 to 600.degree.
C.
[0020] The catalyst obtained in that way displays a higher
catalytic activity than of the silica/alumina gel used as the
starting materials, and furthermore is useable at an industrial
level, by having an axial I breaking strength comprised within the
range of from 20 to 80 kg/cm.sup.2 and a radial breaking strength
comprised within the range of from 3 to 8.5 kg/cm.
[0021] Important features of the catalyst according to the present
invention are the bimodal distribution of porosity, a surface area
comprised within the range of from 300 to 600 m.sup.2/g, and a high
acidity.
[0022] The catalyst according to the present invention can be
suitably used in the usual petrochemical acid-catalysed reactions,
such as alkylation, isomerization and oligomerization of light
olefins, in particular of propylene.
[0023] In particular, the catalyst according to the present
invention is very effective in the reaction of oligomerization of
light olefins, in particular propylene, in order to yield
hydrocarbon cuts showing extremely good qualities as gasoline and
jet fuel.
[0024] The following experimental examples are reported in order to
illustrate the present invention in greater detail.
EXAMPLE 1
Catalyst Preparation
[0025] 40 g of AL--Si gel, prepared as disclosed in European patent
application No. 340,868 is ground in a ball mill and then is
micronized until a powder is obtained with an average distribution
of particles comprised within the range of from 10 to 50 microns.
To such a powder, 40 g of a commercial pseudobohemite (CATAPAL
B-VISTA CHEMICAL COMPANY) is blended by means of a mechanical
mixing procedure. Separately, an aqueous solution of
methylcellulose (METOCEL FLUKA 64625) at 1% by weight is prepared
and is acidified with 0.63 g of glacial CH3COOH (99.8% by
weight).
[0026] The acidified aqueous methylcellulose solution (60-70 g) and
the powder are now thoroughly mixed, until a homogeneous paste is
obtained.
[0027] After performing the extrusion, the extrudate is submitted
to a 4-hour ageing at room temperature, the aged extrudate is dried
at 100.degree. C. for 5 hours, and is calcined at 550.degree. C.
for 8 hours in air.
[0028] At the end of this operation, the catalyst shows a
mechanical strength of 6.4 kg/cm in radial direction and of 42
kg/cm.sup.2 in axial direction, and a specific surface area of 460
m.sup.2/g.
EXAMPLE 2A
Propylene Oligomerization
[0029] The extruded catalyst obtained as disclosed in Example 1 was
tested in the reaction of propylene oligomerization under the
following operating conditions:
[0030] catalyst shape: cylindrical extruded body;
[0031] catalyst dimensions: average diameter approximately 3 mm,
average Length approximately 5 mm;
[0032] reactor type: fixed bed;
[0033] reactor dimensions: inner diameter=36 mm, Length 600 mm;
[0034] feed: propylene/propane mixture in the ratio of 35:65 by
weight;
[0035] reactor temperature: from 100 to 250.degree. C.;
[0036] reactor pressure: from 30 to 50 bars;
[0037] space velocity WHSV: from 0.5 to 2 g of propylene per gram
of active phase per hour.
[0038] The results are reported in Table 1.
1 TABLE 1 WHSV Pressure Temperature Conversion h.sup.-1 bar
.degree. C. rate, % 2 30 140 20 1 30 140 30 1 40 140 37 1 50 150 52
1 40 150 46 0.5 40 150 65 0.5 40 160 72
[0039] The product obtained from the oligomerization is then
distilled, with a fraction useable as gasoline and a fraction
useable as jet fuel being obtained.
[0040] The gasoline fraction displays the following
characteristics:
2 RON 96.8 MON 82.2 d.sub.15 0.7478 C.sub.1-C.sub.4 (% by weight) 1
13-80.degree. C. (% by weight) 3.96 80-175.degree. C. (% by weight)
42.32 175+ (% by weight) 45.72 Olefins (% by weight) 99 Saturated
compounds (% by weight) 1 Aromatics (% by weight) 0
[0041] The jet fuel fraction displays the following
characteristics:
3 Aromatics, % by volume (ASTM D1319) 1.8 Freezing point, .degree.
C. (ASTM D2386) 60 Smoke point, mm (ASTM D1322) 38 Gums, mg/100 ml
(ASTM D381) 49 Flash point, .degree. C. (ASTM D3828) 38 Density at
15.degree. C. (ASTM D1298) 0.7718 Distillation (ASTM D86):
incipient boiling point (.degree. C.): 140 10% by volume (.degree.
C.) 149 20% by volume (.degree. C.) 157 50% by volume (.degree. C.)
184 90% by volume (.degree. C.) 264 end point (.degree. C.):
304
EXAMPLE 2B
Propylene Oligomerization
[0042] The extruded catalyst obtained as disclosed in Example 1 was
tested in the reaction of propylene oligomerization under the
following operating conditions:
[0043] catalyst shape: cylindrical extruded body;
[0044] catalyst dimensions: average diameter approximately 3 mm,
average length approximately 5 mm;
[0045] reactor type: fixed bed;
[0046] reactor dimensions: inner diameter=36 mm, length=600 mm;
[0047] feed: propylene/propane mixture in the ratio of 70:30 by
weight;
[0048] reactor temperature: from 100 to 250.degree. C.;
[0049] reactor pressure: 50 bars;
[0050] space velocity WHSV: 2 g of propylene per gram of active
phase per hour.
[0051] The oligomerization productivity rate resulted to be of 900
g of oligomerized product per each gram of active catalyst
portion.
COMPARISON EXAMPLE 1
Preparation of a Catalytic Extrudate by Mixing Active Phase with a
Thickener
[0052] 80 g of AL--Si gel, prepared as disclosed in European patent
application No. 340,868, is ground in a ball mill and then is
micronized until a powder is obtained which has an average particle
distribution comprised within the range of from 10 to 50 microns.
Such a powder is slowly added to 40 g of water-alcohol solution of
methylcellulose (METOCEL FLUKA 64625) at 1% by weight, with an
effective mechanical stirring. The resulting homogeneous paste is
allowed to age for approximately 1 hour, then is extruded. The
extrudate, having a size comprised within the range of from 3 to 5
mm, is firstly dried at 150.degree. C. for 5 hours and then is
calcined at 500.degree. C. for 8-10 hours. At the end of this
operation, the catalyst displays a low mechanical strength.
COMPARISON EXAMPLE 2
Preparation of a Catalytic Extrudate by Precipitation of Aluminum
Hydroxide
[0053] 40 g of AL--Si gel, prepared as disclosed in European patent
application No. 340,868, is ground in a ball mill and then is
micronized until a powder is obtained which has an average particle
distribution comprised within the range of from 10 to 50 microns.
The powder is added to 905.6 g of an aqueous solution at 11.6% by
weight of AL.sub.2(SO.sub.4).sub.3, kept vigorously stirred.
NH.sub.4OH at 30% by weight is added, until a pH value of 9 is
obtained. The resulting precipitate is washed and filtered
repeatedly, until neutral. The resulting solid material, after
being dried at 100.degree. C. for 2 hours and calcined overnight at
500.degree. C., is ground and micronized again until a
granulometric distribution comprised within the range of from 10 to
50 microns is obtained. Such a powder is slowly added to 72 g of
water-alcohol solution of methylcellulose (METOCEL FLUKA 64625) at
1% by weight, with an effective mechanical stirring. The resulting
homogeneous paste is allowed to age for approximately 1 hour, then
is extruded. The extrudate, having a size comprised within the
range of from 3 to 5 mm, is firstly dried at 150.degree. C. for 5
hours and then is calcined at 500.degree. C. for 8-10 hours. At the
end of this operation, the catalyst displays a mechanical strength
of 1.4 kg/cm in radial direction and of 14 kg/cm.sup.2 in radial
direction, and a specific surface area of 333 m.sup.2/g.
[0054] The resulting extrudate is tested as disclosed in Example 1
(Table 2).
4 TABLE 2 WHSV Pressure Temperature Conversion h.sup.-1 bar
.degree. C. rate, % 2 30 140 3 1 30 140 4 1 40 140 5 1 50 150 8 0.5
40 150 15 0.5 40 160 22
[0055] The catalyst is also tested as disclosed in Example 2B,
resulting in a productivity rate of 300 g of oligomers per each
gram of catalytically active portion.
COMPARISON EXAMPLE 3
Preparation of Unbound Silica/alumina Gel
[0056] The catalyst, prepared as disclosed in European patent
application No. 340,868 was tested for propylene oligomerization
according to as disclosed in Example 2A. The results are reported
in Table 3.
5 TABLE 3 WHSV Pressure Temperature Conversion h.sup.-1 bar
.degree. C. rate, % 2 30 140 3 1 30 140 5 1 40 140 6 1 50 150 10
0.5 40 150 20 0.5 40 160 29
[0057] The data of catalytic activity sets forth the better
performance of the catalyst according to the present invention as
compared to the same catalyst without binding agent, as well as to
the catalyst obtained by means of other techniques.
* * * * *