U.S. patent application number 13/131226 was filed with the patent office on 2011-11-24 for metal loaded catalyst and preparation method thereof.
Invention is credited to Wei Dai, Yi Le, Haijiang Liu, Zuwang Mao, Wei Mu, Hui Peng, Jing Peng, Genshuan Wei, Haibo Yu, Maolin Zhai, Yunxian Zhu.
Application Number | 20110288353 13/131226 |
Document ID | / |
Family ID | 42225214 |
Filed Date | 2011-11-24 |
United States Patent
Application |
20110288353 |
Kind Code |
A1 |
Dai; Wei ; et al. |
November 24, 2011 |
METAL LOADED CATALYST AND PREPARATION METHOD THEREOF
Abstract
A metal loaded catalyst comprises a support and main active
metal components and optional auxiliary active metal components,
wherein the main active metal components are elementary substances
and obtained by ionizing radiation reducing precursors of main
active metal components. The catalyst can be widely used in the
catalytic reactions of petrochemistry industry with high activity
and selectivity. The catalyst can be used directly without being
reduced preliminarily by hydrogen.
Inventors: |
Dai; Wei; (Beijing, CN)
; Peng; Jing; (Beijing, CN) ; Yu; Haibo;
(Beijing, CN) ; Peng; Hui; (Beijing, CN) ;
Wei; Genshuan; (Beijing, CN) ; Zhai; Maolin;
(Beijing, CN) ; Mao; Zuwang; (Beijing, CN)
; Le; Yi; (Beijing, CN) ; Mu; Wei;
(Beijing, CN) ; Liu; Haijiang; (Beijing, CN)
; Zhu; Yunxian; (Beijing, CN) |
Family ID: |
42225214 |
Appl. No.: |
13/131226 |
Filed: |
November 26, 2009 |
PCT Filed: |
November 26, 2009 |
PCT NO: |
PCT/CN2009/001332 |
371 Date: |
August 10, 2011 |
Current U.S.
Class: |
585/250 ;
502/240; 502/300; 502/330; 502/331; 502/339; 502/340; 502/350;
502/355; 502/5; 502/84 |
Current CPC
Class: |
B01J 23/628 20130101;
C10G 45/60 20130101; B01J 37/16 20130101; B01J 23/44 20130101; B01J
35/006 20130101; C10G 45/04 20130101; C10G 45/46 20130101; B01J
23/50 20130101; C10G 45/00 20130101; B01J 23/38 20130101; C10G
47/10 20130101; B01J 23/626 20130101; B01J 37/34 20130101; B01J
37/344 20130101; C10G 47/12 20130101; B01J 23/681 20130101; B01J
23/6447 20130101; C10G 47/02 20130101; C10G 49/02 20130101; B01J
23/70 20130101; B01J 37/04 20130101; C10G 35/06 20130101; B01J
23/40 20130101; B01J 21/04 20130101; B01J 23/8926 20130101; C10G
45/34 20130101; B01J 37/0232 20130101 |
Class at
Publication: |
585/250 ;
502/300; 502/339; 502/330; 502/331; 502/5; 502/355; 502/240;
502/350; 502/340; 502/84 |
International
Class: |
C07C 5/00 20060101
C07C005/00; B01J 23/44 20060101 B01J023/44; B01J 23/66 20060101
B01J023/66; B01J 23/89 20060101 B01J023/89; B01J 21/16 20060101
B01J021/16; B01J 21/04 20060101 B01J021/04; B01J 21/08 20060101
B01J021/08; B01J 21/06 20060101 B01J021/06; B01J 21/10 20060101
B01J021/10; B01J 29/00 20060101 B01J029/00; B01J 35/02 20060101
B01J035/02; B01J 37/34 20060101 B01J037/34 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 26, 2008 |
CN |
200810227414.2 |
Apr 17, 2009 |
CN |
200910082421.2 |
Apr 29, 2009 |
CN |
200910083212.X |
Claims
1-15. (canceled)
16. A supported metal catalyst, comprising a carrier and supported
thereon a primary metal active component and an optional secondary
metal active component, and prepared by a method comprising
applying ionizing radiation on a system comprising the primary
metal active component precursor, the carrier, a free radical
scavenger and water, to reduce at least the primary metal active
component precursor into the primary metal active component in
elementary state, wherein the step of applying the ionizing
radiation to carry out the reduction is conducted in any of the
following manners: a) wetting the carrier having the primary metal
active component precursor supported thereon with an aqueous
solution comprising the free radical scavenger, and then
irradiating the wetted carrier, preferably in vacuum or under inert
atmosphere; and b) mixing the carrier having the primary metal
active component precursor supported thereon with an aqueous
solution comprising the free radical scavenger, and then
irradiating the carrier immersed in the solution.
17. The catalyst of claim 16, comprising: the carrier; and
supported thereon the following components: a) the primary metal
active component, which is one of the elements of Group VIII and
Group IB, in an amount ranging from 0.01 wt % to 20 wt %, based on
the total weight of the carrier; and b) the optional secondary
metal active component, which is at least one metal chosen from
Group VIII elements, Group IB elements, Bi, Sb, In, Cs and Rb, in
an amount ranging from 0 wt % to 20 wt %, based on the total weight
of the carrier; if present, the component b) being different from
the component a).
18. The catalyst of claim 17, wherein the primary metal active
component a) is present in an amount ranging from 0.01 wt % to 10
wt %, based on the total weight of the carrier; and the secondary
metal active component b) is present in an amount ranging from 0 wt
% to 10 wt %, based on the total weight of the carrier.
19. The catalyst of claim 17, wherein the optional secondary metal
active component b) is present in the catalyst as an elementary
metal or as a metal oxide.
20. The catalyst of claim 16, wherein the carrier is chosen from
Al.sub.2O.sub.3, SiO.sub.2, TiO.sub.2, MgO, diatomite, molecular
sieves, clays and mixtures thereof.
21. The catalyst of claim 20, wherein the carrier is of pellet
shape, spherical shape, tablet shape, tooth-spherical shape, strip
shape, or trilobal shape.
22. The catalyst of claim 16, wherein the catalyst has an
appearance exhibiting light grey, grey, black, bluish light grey,
bluish grey, or bluish black.
23. A method for the preparation of the catalyst of claim 16,
comprising applying ionizing radiation on a system comprising the
primary metal active component precursor, the carrier, a free
radical scavenger and water, to reduce at least the primary metal
active component precursor into the primary metal active component
in elementary state, wherein the step of applying the ionizing
radiation to carry out the reduction is conducted in any of the
following manners: a) wetting the carrier having the primary metal
active component precursor supported thereon with an aqueous
solution comprising the free radical scavenger, and then
irradiating the wetted carrier, preferably in vacuum or under inert
atmosphere; and b) mixing the carrier having the primary metal
active component precursor supported thereon with an aqueous
solution comprising the free radical scavenger, and then
irradiating the carrier immersed in the solution.
24. The method of claim 23, wherein the ionizing radiation used is
.gamma.-ray, X-ray or electron beam.
25. The method of claim 23, wherein the ionizing radiation used has
an adsorption dose rate of from 1 to 1.times.10.sup.7 Gy/min, and
wherein the ionizing radiation used has an adsorption dose of from
0.01 to 1.times.10.sup.5 kGy.
26. The method of claim 23, wherein the primary metal active
component precursor is a corresponding compound of the primary
metal active component, which is chosen from chlorides, nitrates,
acetates, sulfates and organic metallic compounds.
27. The method of claim 23, wherein prior to the radiation
reduction, the carrier having the primary metal active component
precursor supported thereon is treated with a fixing agent, which
is a basic compound, preferably an aqueous solution of sodium
hydroxide, potassium hydroxide, sodium bicarbonate or sodium
carbonate, or ammonia water.
28. The method of claim 23, wherein the free radical scavenger is
at least one chosen from alcohols and formic acid, and preferably
at least one chosen from methanol, ethanol, ethylene glycol,
isopropyl alcohol and formic acid.
29. The method of claim 23, further comprising supporting a
secondary metal active component or a precursor thereof on the
carrier, before, during, or after the ionizing radiation
reduction.
30. A method for converting an organic compound, comprising
contacting a feedstock to be converted with the catalyst of claim
16 under conversion conditions.
Description
CROSS REFERENCE OF RELATED APPLICATIONS
[0001] The present application claims the benefits of Application
No. CN 200810227414.2 as filed on Nov. 26, 2008, CN 200910082421.2
as filed on Apr. 17, 2009, and CN 200910083212.X as filed on Apr.
29, 2009, which are incorporated herein by reference in their
entirety and for all purposes.
TECHNICAL FIELD
[0002] The invention relates to a supported metal catalyst, a
method for preparing the same, and use of the same in a reaction
for converting an organic compound.
BACKGROUND ART
[0003] Catalysts are basis of modern petrochemical industry, and
supported metal catalysts, as an important class of catalysts, are
widely used in applications such as oil refining, basic chemical
feedstock preparation, fine chemicals industry, and the like. For
example, Ni/SiO.sub.2--Al.sub.2O.sub.3 or Pd/molecular sieve
catalysts have been used in hydrocracking to produce gasoline and
other fuels; Pt/Al.sub.2O.sub.3 catalysts have been used in the
catalytic reforming of naphtha to prepare high octane number
gasoline, arenes and liquefied petroleum gas, and isomerization of
light gasoline, alkanes or xylenes; Ni/Al.sub.2O.sub.3 catalysts
have been used in methanation; Ag/Al.sub.2O.sub.3 catalysts have
been used in the reaction for preparing ethylene oxide from
ethylene; Pd/Al.sub.2O.sub.3 catalysts have been used in the
selective hydrogenation of olefins, alkynes in pyrolysis gasoline
or dienes, etc.
[0004] A supported metal catalyst consists typically of a carrier,
a primary metal active component and an optional secondary metal
active component. The carrier is a framework supporting the active
components and also functions to enhance utilization rate of the
active components, enhance heat stability of the catalyst, provide
active centers, and the like. Commonly used carrier materials
include alumina, silica, molecular sieves, active carbon, magnesia,
titania, diatomite, and the like. The primary metal active
component is generally a metal element with catalytic activity, and
typically an element from Group VIII, such as Pd, Pt, Ni, and the
like. The secondary metal active component may be used to modify
the activity or selectivity of the catalyst, and commonly used
secondary metal active components include Cu, Ag, Au, and the
like.
[0005] Currently, a supported metal catalyst is typically produced
by an impregnation-calcination process comprising contacting
sufficiently a solution containing a metal active component
precursor (typically, a solution of a salt) with a prepared
carrier, to support the metal active component precursor on the
carrier; and drying and then calcining at a high temperature the
carrier having metal active component precursor supported thereon,
to decompose the metal active component precursor into
corresponding oxides. After loaded in a reactor, so-prepared
catalyst is typically subjected to a pre-reduction treatment, i.e.,
reducing the metal oxides with hydrogen gas to elementary metal
prior to use. Problems suffered by such impregnation-calcination
processes for the preparation of a catalyst are that the
calcination process consumes a large amount of energy, and that the
high temperature involved in the process may cause the sintering of
the metal active component particles and/or the carrier, resulting
in the deterioration of the catalyst performance.
[0006] In order to avoid the influence of the sintering phenomenon
on the catalyst performance, many of later catalyst preparation
methods remove the high temperature calcination step, and use a
chemical reduction process conducted at lower reaction temperature
instead, along with heating or activating the system with
ultrasonic wave, microwave, UV light, plasma, and the like, so that
the catalyst performance is improved to some extent.
[0007] U.S. Pat. No. 5,968,860 discloses a method for preparing a
hydrogenation catalyst useful in the gas phase production of vinyl
acetate from ethylene, which method comprises supporting a Pd
active component precursor and the like on a carrier and reducing
the Pd active component precursor-supported carrier with sodium
borohydride, hydrazine or formic acid at room temperature, wherein
an ultrasonic wave activating step is included in the preparation.
The resultant catalyst sample has a higher selectivity.
[0008] Chinese patent application CN 1579618 describes a method for
preparing a supported metal catalyst, which method uses microwave
radiation as heat source and a polyol as reducing agent and
protecting agent, and can be used to rapidly prepare a
multi-component supported catalyst having a supporting amount of
from 1 wt % to 99 wt % and a particle size of metal particles
controllable to 0.5 to 10 nm.
[0009] Chinese patent application CN 1511634 describes a method for
preparing a catalyst useful in the selective hydrogenation of
ethyne to ethylene. The method uses a radio-frequency plasma to
activate and decompose a Pd precursor supported on Al.sub.2O.sub.3
at mild conditions and then carries out H.sub.2 reduction, to give
a catalyst characterized by high low-temperature activity and high
selectivity.
[0010] U.S. Pat. No. 6,268,522 utilizes UV light reduction process
to prepare a hydrogenation catalyst. Irradiating a carrier having
an active component precursor and a sensitizing agent impregnated
thereon with UV light will cause reduction in the surface layer
portion so that the active component will be distributed in an
eggshell shape, and the shell thickness can be controlled via the
conditions, e.g. UV radiation wavelength, radiation power and
irradiating time. After extracting the un-reduced active component
precursor with a solvent, the resultant sample exhibits good
activity and selectivity in the reaction for the gas phase
production of vinyl acetate from ethylene.
[0011] In the above improved methods, microwave and UV light belong
to electromagnetic radiation. Microwave is an electromagnetic wave
having a wavelength ranging from 1 to 1000 mm, and it heats a
system through rapid turn of polar molecules under the action of
high frequency electric field and is a heating method per se. UV
light is an electromagnetic wave having a wavelength ranging from
10 to 400 nm, and its photons have an energy range in accordance
with that required to excite molecules so that they can be
selectively absorbed by the molecules to excite the molecules and
cause chemical reactions. Ultrasonic wave is mechanical vibration,
and it applies some influence on the performance of a catalyst
through the action of vibration energy on the catalyst. Plasma
belongs to low-energy, charge-born particles, and it decomposes and
activates an active component precursor through complex chemical
reactions between the large amount of charge-born particles and the
active component precursor. In the above improved methods, the
plasma treatment is an activating method replacing for the
calcination step, microwave and ultrasonic wave essentially provide
heat source to the chemical reduction process, and only UV
radiation can cause reduction reaction of the active component
precursor. However, since UV light has a poor penetrating ability
for a solid, it can act on only the surface layer of the catalyst
and can hardly be used in the production of a mass of product.
Furthermore, these methods involve complicated operations, and
generally require the use of a large amount of compounds as
reducing agent, protecting agent or solvent. Taking into account
the economic issues involved in the preparation of a mass of a
catalyst, it is difficult for these methods to be used in
commercial production.
[0012] Thus, there is still a need for providing a simple,
effective method that can be used to prepare a supported metal
catalyst with good activity and selectivity.
SUMMARY OF THE INVENTION
[0013] In order to overcome the problems suffered by the known
techniques, the inventors have diligently conducted studies. As a
result, the inventors have found that it is possible to utilize
ionizing radiation reduction process to prepare a supported metal
catalyst, and that the resultant catalyst has excellent
performance. The present invention has been made on this basis.
[0014] An object of the invention is to provide a supported metal
catalyst comprising a carrier and supported thereon a primary metal
active component and an optional secondary metal active component,
wherein the primary metal active component is in elementary state
and is formed by reducing a precursor of the primary metal active
component by means of ionizing radiation.
[0015] Another object of the invention is to provide a method for
preparing the supported metal catalyst, comprising reducing a
precursor of the primary metal active component by means of
ionizing radiation to form the primary metal active component in
elementary state supported on the carrier.
[0016] Still another object of the invention is to provide use of
the catalyst of the invention in a conversion process of an organic
compound.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] FIG. 1 is transmission electron microscope (TEM) photographs
showing the dispersion of Pd particles in catalysts prepared in
inventive examples and comparative examples.
[0018] FIG. 2 is the XPS spectrum of the Pd/Al.sub.2O.sub.3
catalyst from Example 1.
[0019] FIG. 3 is the XPS spectrum of a Pd/Al.sub.2O.sub.3 catalyst
prepared though a known technique.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0020] Ionizing radiation is a generic term covering all radiations
capable of ionizing a substance, and includes high-energy
electromagnetic radiations having a wavelength of less than
10.sup.-8 meter and high-energy particle radiations, such as X-ray,
.gamma.-ray, electron beam, high-energy proton, and the like.
.GAMMA.-ray is a most commonly used ionizing radiation, and is
generally generated by a .sup.60Co or .sup.137Cs radiation source.
Unlike low-energy electromagnetic radiations such as UV light,
ionizing radiation has energy much higher than the exciting energy
of molecules so that it can ionize directly molecules, thereby
generating a series of active particles and causing reactions such
as reduction. In basic studies, reduction reaction caused by
ionizing radiation has been used to prepare nanometer elementary
metal powder dispersed in a solution system.
[0021] The inventors have found that the use of ionizing radiation
reduction process in the preparation of a supported metal catalyst
has unique advantages: (1) ionizing radiation reduction process can
be carried out at normal temperature or low temperature, and the
reaction progress can be easily controlled by absorbed dose rate
and absorbed dose; (2) .gamma.-ray and electron beam have strong
penetrating ability so that they can be used in large-scale
preparation; (3) when causing the reduction of the active component
precursor to the elementary active component, the energy of the
ionizing radiation is also absorbed by the carrier, thereby
altering the energy state of the carrier surface, resulting in that
the formed elementary active component bonds tightly to the
carrier; (4) the operation of ionization irradiating is simple, and
the existing large-scale industrial irradiation sources can be used
directly in the production of catalysts.
[0022] Thus, in the first aspect, the invention provides a
supported metal catalyst, comprising a carrier and supported
thereon a primary metal active component and an optional secondary
metal active component, wherein the primary metal active component
is in elementary state and is formed by reducing a precursor of the
primary metal active component by means of ionizing radiation.
[0023] In an embodiment, the supported metal catalyst of the
invention comprises: [0024] a carrier; and [0025] supported thereon
the following components:
[0026] a) a primary metal active component, which is one of the
elements of Group VIII and Group IB, in an amount ranging from 0.01
wt % to 20 wt %, based on the total weight of the carrier; and
[0027] b) an optional secondary metal active component, which is at
least one metal chosen from Group VIII elements, Group IB elements,
Bi, Sb, In, Cs and Rb, in an amount ranging from 0 wt % to 20 wt %,
based on the total weight of the carrier;
[0028] if present, the component b) being different from the
component a).
[0029] The catalyst of the invention comprises a primary metal
active component present in its elementary state, which is
preferably one member chosen from Group VIII elements and Group IB
elements, more preferably from Pd, Pt and Ni, and still more
preferably Pd. The content of the primary metal active component
ranges from 0.01 wt % to 20 wt %, preferably from 0.01 wt % to 10
wt %, and more preferably from 0.02 wt % to 1 wt %, based on the
total weight of the carrier.
[0030] The catalyst of the invention comprises optionally a
secondary metal active component, which is present in the catalyst
in elementary state or in an oxidized state. The secondary metal
active component is preferably at least one metal chosen from Group
VIII elements, Group IB elements, Bi, Sb, In, Cs and Rb, and more
preferably from Ag, Au, Cu, Bi, In, Cs, Rb and Group VIII elements
other than the component a). The content of the secondary metal
active component ranges from 0 wt % to 20 wt %, and preferably from
0 wt % to 10 wt %, based on the total weight of the carrier.
[0031] The catalyst of the invention also comprises optionally
other auxiliary agents that are commonly used in hydrogenation
catalysts to adjust catalytic performance, such as alkali metal,
alkali earth metal, halogen, etc., of which content ranges from 0
wt % to 5 wt %, based on the total weight of the carrier.
Information about the combinations of the metal active components
and the auxiliary agents in supported metal catalysts has been
disclosed in many literatures, such as EP0689872 and US
20040024272, which are incorporated herein by reference.
[0032] Preferably, the carrier used in the catalyst of the
invention is chosen from Al.sub.2O.sub.3, SiO.sub.2, TiO.sub.2,
MgO, diatomite, molecular sieves, clays, and mixtures thereof.
Preferably, the carrier is of pellet shape, spherical shape, tablet
shape, tooth-spherical shape, strip shape, or unusual strip shape
such as trilobal shape. Preferably, a carrier having a specific
surface area of from 1 to 200 m.sup.2/g is used.
[0033] In general, the catalyst of the invention has an appearance
exhibiting light grey, grey, black, bluish light grey, bluish grey
or bluish black.
[0034] In the supported metal catalyst of the invention, the
primary metal active component in elementary state is formed by
reducing a primary metal active component precursor in the presence
of the carrier by means of ionizing radiation. More details about
the ionizing radiation reduction will be further discussed
hereinbelow.
[0035] In an embodiment, the catalyst of the invention is ones
suitable for the selective hydrogenation of ethyne to ethylene
and/or the selective hydrogenation of propyne and propadiene to
propylene, comprising: [0036] a carrier, and [0037] supported
thereon the following components:
[0038] a) palladium as primary metal active component present in
the form of elementary particles on the surface of the carrier, of
which content ranges from 0.01 wt % to 1 wt %, based on the total
weight of the carrier, of which average particle size ranges from 1
to 100 nm, and which is formed by ionizing radiation reducing a
palladium precursor;
[0039] b) an optional secondary metal active component, which is at
least one selected from the group consisting of Group VIII metals
other than palladium, Group IB metals, Bi, Sb, Pb, In, Cs, Rb, K
and Mg, in an amount ranging from 0 to 20 wt %, based on the total
weight of the carrier.
[0040] In this embodiment, the primary metal active component,
palladium, is present on the surface of the carrier, and the
thickness of the palladium layer is preferably from 1 to 500 .mu.m.
The content of palladium is from 0.01 to 1 wt %, and preferably
from 0.01 to 0.4 wt %, based on the total weight of the carrier.
The average particle size of palladium is from 1 to 100 nm,
preferably from 1 to 40 nm, and more preferably from 1 to 10
nm.
[0041] In this embodiment, if present, the secondary metal active
component is not specifically limited with respect to its
distribution and state. The secondary metal active component may be
distributed on the surface of the carrier, or in the carrier; and
it can be present in elementary state and/or in oxidized state. The
content of the secondary metal active component is from 0 to 20 wt
%, preferably from 0 to 5 wt %, and more preferably from 0.001 to 2
wt %, based on the total weight of the carrier. Preferably, the
weight ratio of the primary metal active component, palladium, to
the secondary metal active component is from 0.01-50.
[0042] In a preferred embodiment, the catalyst suitable for the
selective hydrogenation of ethyne further comprises other auxiliary
agents that are commonly used in hydrogenation catalysts to adjust
catalytic performance, such as halogen, in a usual amount.
[0043] In another embodiment, the catalyst of the invention is ones
suitable for the hydrogenation of an unsaturated hydrocarbon, in
particular the hydrogenation of C4 and/or C5 unsaturated
hydrocarbon(s), comprising: [0044] a carrier, and [0045] supported
thereon the following components:
[0046] 1) elementary Pd as primary metal active component, of which
content ranges from 0.01 wt % to 1 wt %, and preferably from 0.01
wt % to 0.8 wt %, based on the total weight of the carrier, and
which is formed by ionizing radiation reducing a palladium
precursor;
[0047] 2) at least one chosen from Ag, Cu, Au, Pb, Zn, Bi, Mn and
Mo, of which content ranges from 0.01% to 5%, based on the total
weight of the carrier; and
[0048] 3) optionally, at least one chosen from alkali metals and
alkali earth metals, and preferably one or two chosen from Li, Na,
K, Mg, Ca and Ba, of which content ranges from 0 wt % to 3 wt %,
based on the total weight of the carrier.
[0049] In this embodiment, the primary metal active component,
palladium, is present on the surface of the carrier, and the
thickness of the palladium layer is preferably from 1 to 500 .mu.m.
The content of palladium is from 0.01 to 1 wt %, preferably from
0.01 to 0.8 wt %, and more preferably from 0.01 to 0.6 wt %, based
on the total weight of the carrier. The average particle size of
palladium is from 1 to 100 nm, preferably from 0.5 to 40 nm, and
more preferably from 1 to 15 nm. The component 2) is generally in a
chemical valence state lower than its chemical valence in its
normal oxide, and is preferably at least one of Ag, Pb and Cu, and
its content ranges from 0.01 wt % to 5%, and preferably from 0.01
wt % to 3 wt %, based on the total weight of the carrier. The
component 3) is generally present in the form of metal salt or
oxide, and is preferably at least one of K, Na and Ca, and its
content in terms of metal ranges from 0 wt % to 3 wt %, and
preferably from 0.01 wt % to 2 wt %, based on the total weight of
the carrier.
[0050] In still another embodiment, the catalyst of the invention
is ones suitable for the selective hydrogenation of pyrolysis
gasoline, comprising: [0051] a carrier, and [0052] supported
thereon the following components:
[0053] 1) elementary palladium as primary metal active component,
of which content ranges from 0.01 wt % to 2 wt %, preferably from
0.05 wt % to 1 wt %, and more preferably from 0.05 wt % to 0.5 wt
%, based on the total weight of the carrier, and which is formed by
ionizing radiation reducing a palladium precursor;
[0054] 2) optionally, a secondary metal active component, which is
at least one chosen from Sn, Pb, Cu, Ga, Zn, Ag, Sb, Mn, Co, Mo, W,
Si and P, and preferably Sn and/or Pb, and content of which ranges
from 0 wt % to 3 wt %, and more preferably from 0 wt % to 2 wt %,
based on the total weight of the carrier; and
[0055] 3) optionally, at least one of K, Mg, Ca and Ba, and
preferably Mg or/and Ca, of which content ranges from 0 w % to 5 wt
%, preferably from 0 w % to 3 wt %, and more preferably from 0 wt %
to 0.8 wt %, based on the total weight of the carrier.
[0056] In the second aspect, the invention provides a method for
the preparation of the supported metal catalyst of the invention,
comprising applying an ionizing radiation on a system comprising a
primary metal active component precursor, a carrier, a free radical
scavenger and water, to reduce at least the primary metal active
component precursor to the primary metal active component in
elementary state.
[0057] The step of applying an ionizing radiation to carry out the
reduction is conducted in any of the following manners:
[0058] a) wetting the carrier having the primary metal active
component precursor supported thereon with an aqueous solution
comprising the free radical scavenger, and then irradiating the
wetted carrier, preferably in vacuum or under inert atmosphere;
[0059] b) mixing the carrier having the primary metal active
component precursor supported thereon with an aqueous solution
comprising the free radical scavenger, and then irradiating the
carrier immersed in the solution; and
[0060] c) mixing the carrier with an aqueous solution comprising
the free radical scavenger and the primary metal active component
precursor, and then irradiating the carrier immersed in the
solution.
[0061] In the manners a) and b), the primary metal active component
precursor is first supported on the carrier, then the carrier
having the primary metal active component precursor supported
thereon is combined with an aqueous solution containing the free
radical scavenger so that the carrier is wetted with or immerged in
the solution, and then the carrier is irradiated with the ionizing
radiation. In the manner c), the carrier is directly mixed with an
aqueous solution containing the free radical scavenger and the
primary metal active component precursor, and then the carrier
immerged in the solution is irradiated with the ionizing
radiation.
[0062] The primary metal active component precursor is a
corresponding metal compound of the metal active component, and its
examples include, but are not limited to, chlorides, nitrates,
acetates, sulfates and organometallic compounds.
[0063] In the case where the ionizing radiation reduction is
carried out in the above manner a) or b), the primary metal active
component precursor may be supported on the carrier by a process
commonly used in catalyst preparation, for example, spray coating,
incipient-wetness impregnation, over-saturated impregnation, and
the like. When an over-saturated impregnation process is used, if
the primary metal active component precursor in the impregnation
liquid cannot be completely adsorbed by the carrier, then the
volume of the impregnation liquid and the concentration of the
primary metal active component precursor should be determined
according to the adsorption ratio to ensure that the amount of the
primary metal active component supported on the carrier meets the
predetermined requirement. In the case where the primary metal
active component precursor is impregnated onto the carrier, the
impregnation may be conducted in one or more steps. Examples of the
solvent used during the impregnation including, but are not limited
to, water, hydrochloric acid, nitric acid, acetic acid, alcohols,
and mixtures thereof; and preferably water. The concentration of
the solution used in the supporting operation may vary widely.
Preferably, the concentration of the metal active component in the
solution ranges from 0.1 mg/ml to 200 mg/ml.
[0064] In the case where the primary metal active component
precursor is supported onto the carrier, the acidity/basicity of
the supported product may influence the subsequent radiation
reduction process. In order to make the acidity/basicity of the
supported product be in favor of the progress of the radiation
reduction, it can be adjusted by using the following methods:
[0065] (1) adjusting the pH of the primary metal active component
supporting solution to 2-14, and preferably to 2-9, with a solution
of, for example, NaOH, KOH, ammonia, sodium carbonate, sodium
bicarbonate, or the like; and/or
[0066] (2) treating the carrier with a fixing agent before loading
the primary metal active component precursor; or treating the
carrier having the primary metal active component precursor
supported thereon with a fixing agent after loading the primary
metal active component precursor but before carrying out the
radiation reduction, with the fixing agent being a basic compound,
and preferably an aqueous solution of NaOH, potassium hydroxide,
sodium bicarbonate or sodium carbonate, or ammonia water. The
treatment may be conveniently carried out, for example, by spray
coating the fixing agent on the carrier with/without the supported
primary metal active component precursor. Without limited to a
theory, it is believed that the fixing agent converts a soluble
metal salt into an insoluble metal compound fixed on the surface of
the carrier.
[0067] Optionally, but less preferably, prior to the ionizing
radiation reduction, the carrier having the primary metal active
component precursor supported thereon may be calcined at a high
temperature so as to convert the metal active component precursor
into oxides.
[0068] In the case where the ionizing radiation reduction is
carried out in the above-mentioned manner c), it is preferred to
treat the carrier with said fixing agent, prior to the radiation
reduction. In general, the fixing agent may be combined with the
carrier by spray coating.
[0069] In the method of the invention, the ionizing radiation
reduction is carried out in the presence of an aqueous medium
containing the free radical scavenger. Without limited to a theory,
it is believed that, when the ionizing radiation acts on the
aqueous medium, water is radiolytically decomposed to generate
hydrated electron (e.sub.aq.sup.-), hydrogen atom (.H), hydroxyl
free radical (.OH), hydrated hydrogen ion (H.sub.3O.sup.+), and the
like. Among these, e.sub.aq.sup.- is a strong reducing agent and
can reduce most of metals in oxidized state to elementary metal.
Metal atoms formed through the reduction grow on the surface of the
carrier and are finally stabilized by the carrier, thereby forming
metal particles having catalytic activity. However, the radiolysis
of water generates simultaneously oxidizing free radicals such as
.OH, which may re-oxidize the metal atoms just generated in the
radiation reduction process. In order to avoid such a side
reaction, an amount of the free radical scavenger is included in
the irradiated system, and the free radical scavenge reacts with
the oxidizing free radicals such as .OH to form a more stable free
radical or a reducing free radical, thereby improving the reduction
ability of the system.
[0070] The free radical scavenger useful in the preparation method
according to the invention may be chosen from: C1-C6 alcohols and
derivatives thereof, such as ethanol, ethylene glycol, isopropyl
alcohol, tert-butyl alcohol, ascorbic acid and formic acid. The
free radical scavenger is preferably isopropyl alcohol or ethylene
glycol.
[0071] Preferably, the reaction medium of the ionizing radiation
reduction is a solution of the free radical scavenger in water,
which contains from 0.5 vol % to 98 vol %, preferably from 1 vol %
to 70 vol %, and more preferably from 2 vol % to 60 vol % of the
free radical scavenger.
[0072] The ionizing radiation used in the present method may be
chosen from .gamma.-ray, X-ray and electron beam. The radiation
source may be chosen from .sup.60Co (.gamma. source), .sup.137Cs
(.gamma. source), X-ray source and electron accelerator (electron
beam), preferably from .sup.60Co, X-ray source and electron
accelerator, and more preferably .sup.60Co.
[0073] Depending on the composition of the primary metal active
component precursor, the acidic/basic condition of the carrier
surface and the irradiation conditions, the absorbed dose required
to reduce completely the primary metal active component precursor
may vary from 0.01 to 1.times.10.sup.5 kGy, and preferably from 5
to 100 kGy. A person skilled in the art can readily determine the
suitable dose required to reduce completely the primary metal
active component.
[0074] The absorbed dose rate of the ionizing radiation may vary
from 1 to 1.times.10.sup.7 Gy/min, preferably from 10 to 10000
Gy/min, and more preferably from 20 to 100 Gy/min.
[0075] The ionizing radiation reduction process may be carried out
at room temperature or a lower temperature, and preferably at room
temperature.
[0076] If desired, the secondary metal active component or its
precursor may be supported on the carrier before, during or after
the ionizing radiation reduction. In an embodiment, the secondary
metal active component or its precursor and the primary metal
active component precursor are supported, simultaneously or
successively, on the carrier by, for example, spray coating process
or impregnating process, and then the ionizing radiation reduction
is carried out. In another embodiment, the carrier is mixed with an
aqueous solution containing the secondary metal active component or
its precursor, the free radical scavenger, and the primary metal
active component precursor, and then the resultant mixture is
irradiated with the ionizing radiation, to obtain the catalyst
comprising the primary metal active component and the secondary
metal active component. In another embodiment, after the ionizing
radiation reduction step, the secondary metal active component is
supported on the carrier having the primary metal active component
supported thereon by, for example, spray coating process or
impregnating process. The timing for supporting the secondary metal
active component or its precursor may be selected according to the
desired form of the secondary metal active component and
considering the simplicity of the preparation method, and this is
within the knowledge of a person skilled in the art. The
preferences given when discussing the supporting of the primary
metal active component precursor are applicable similarly to the
secondary metal active component or its precursor.
[0077] If desired, other auxiliary agents used to adjust the
catalytic performance, such as halogen, may be supported on the
carrier before, during or after the ionizing radiation reduction.
The timing and manner for supporting the auxiliary agents may be
readily determined by a person skilled in the art.
[0078] In the method of the invention, the carrier having subjected
to the ionizing radiation reduction or the carrier having subjected
to the ionizing radiation reduction and the further supporting of
the secondary metal active component and/or the other auxiliary
agents is washed with a suitable amount of de-ionized water and
then dried, or directly dried without the washing, to give the
catalyst of the invention. The drying may be carried out under air
atmosphere or under vacuum, and preferably under air atmosphere.
The temperature for the drying may ranges from 40 to 200.degree.
C., and preferably from 50 to 120.degree. C. The drying time may
ranges from 3 to 48 hours, and preferably from 5 to 24 hours.
[0079] In the third aspect, the invention relates to the use of the
present catalyst in an organic compound conversion reaction. The
organic compound conversion reactions include, but are not limited
to, selective hydrogenation of ethyne in an ethylene stream to
ethylene; selective hydrogenation of propyne and propadiene in a
propylene stream to propylene; hydrogenation of an unsaturated
hydrocarbon, especially hydrogenation of C4 and/or C5 unsaturated
hydrocarbon; selective hydrogenation of alkynes in a pyrolysis
gasoline; catalytic reforming; hydrocracking; and
isomerization.
[0080] The supported metal catalyst and the preparation method
thereof according to the invention have the following
advantages:
[0081] (1) the catalyst of the invention has a primary metal active
component in metal elementary state so that the catalyst can be
used directly, without needing the reduction with hydrogen gas
prior to use;
[0082] (2) in contrast to the catalysts prepared through a
calcination decomposition process, the catalyst of the invention is
prepared at a normal temperature so that the high-temperature
sintering of active component particles and/or carrier material is
avoided, and the catalyst of the invention has generally higher
activity and selectivity;
[0083] (3) during the ionizing radiation reduction, the radiation
energy is absorbed simultaneously by the carrier and the solution
system so that, while the metal ion is reduced to elementary metal,
the energy state of the surface of the carrier is also changed,
resulting in enhanced interaction between the formed metal
particles and the carrier; thus, compared to the conventional
methods, the present method provides a catalyst having more
uniformly dispersed and more tightly bonded metal particles and
better reaction performance;
[0084] (4) since in the preparation of the catalyst, conditions
such as the kind of the carrier, pH of the impregnating liquid,
impregnating time, supporting method, the state of the carrier when
irradiated, the kind and content of the free radical scavenger,
radiation dose rate, etc. will influence the particle size and
distribution of the formed active component particles of the
catalyst, it is possible to prepare conveniently catalysts having
different characteristics by means of the method of the invention,
by adjusting and controlling the above preparation conditions, to
meet the requirements of different catalytic reactions;
[0085] (5) the method for preparing the catalyst of the invention
is simple, and can significantly reduce energy consumption and
gaseous pollutant emission, compared to the conventional
methods;
[0086] (6) the .gamma.-ray, X-ray or electron beam used in the
ionizing radiation reduction process according to the invention
have strong penetrating ability, and the existing large-scale
industrial irradiation sources can be used directly in the
production of a mass of a catalyst.
EXAMPLES
[0087] The following examples are given for further illustrating
the invention, but do not make limitation to the invention in any
way.
Example 1
[0088] 17 ml of solution of PdCl.sub.2 in hydrochloride acid having
a Pd content of 2 mg/ml was diluted with 30 ml of de-ionized water
and then neutralized with 1 N NaOH solution to pH value of 3.0.
So-obtained solution was uniformly spray coated on 100 g of
Al.sub.2O.sub.3 carrier. The carrier was sufficiently wetted with
20 ml of 50% solution of isopropyl alcohol in water, and then
irradiated under vacuum with a .sup.60Co .gamma. radiation source
at a dose rate of 30 Gy/min for 15 h. The irradiated sample was
washed with de-ionized water four times, and then dried at
60.degree. C. for 12 hours, to give Catalyst A. Catalyst A has a
grey appearance, a Pd content of 0.034 wt %, and an average
diameter of Pd particles of 3.3 nm.
Example 2
[0089] 25 ml of solution of PdCl.sub.2 in hydrochloride acid having
a Pd content of 2 mg/ml was diluted with 25 ml of de-ionized water
and then neutralized with 1 N NaOH solution to pH value of 3.0. 100
g of Al.sub.2O.sub.3 carrier was added into the above prepared
PdCl.sub.2 solution and impregnated for 20 min. Then 10 ml of
isopropyl alcohol was added into the impregnation solution, and
after uniformly mixed, the resultant mixture was transferred into a
test tube. The test tube was stopped and then irradiated with a
.sup.60Co .gamma. radiation source at a dose rate of 30 Gy/min for
15 h. The irradiated sample was washed with de-ionized water four
times, and then dried at 60.degree. C. for 12 hours, to give
Catalyst B. Catalyst B has a grey appearance, a Pd content of 0.033
wt %, and an average diameter of Pd particles of 5.4 nm.
Example 3
[0090] 13.5 ml of solution of Pd(NO.sub.3).sub.2 in nitric acid
having a Pd content of 10 mg/ml was diluted with 30 ml of
de-ionized water and spray coated on 100 g of Al.sub.2O.sub.3
carrier. Then 10 ml of 3N NaOH solution was spray coated on the
carrier to fix the palladium salt. The carrier was sufficiently
wetted with 20 ml of 50% solution of isopropyl alcohol in water,
and then irradiated in N.sub.2 atmosphere with a .sup.60Co .gamma.
radiation source at a dose rate of 60 Gy/min for 8 h. The
irradiated sample was dried at 60.degree. C. for 12 h, to give
Catalyst C. Catalyst C has an off-white appearance, a Pd content of
0.135 wt %, and an average diameter of Pd particles of 2.9 nm.
Example 4
[0091] 13.5 ml of solution of PdCl.sub.2 in hydrochloride acid
having a Pd content of 10 mg/ml and 35 ml of de-ionized water were
combined and spray coated on 100 g of Al.sub.2O.sub.3 carrier.
After drying, 27 ml of AgNO.sub.3 aqueous solution having a Ag
content of 5 mg/ml and 10 ml of 3N NaOH solution were successively
spray coated on the carrier. The carrier was sufficiently wetted
with 20 ml of 50% solution of isopropyl alcohol in water, and then
irradiated under vacuum with a .sup.60Co .gamma. radiation source
at a dose rate of 30 Gy/min for 15 h. The irradiated sample was
dried at 60.degree. C. for 12 h, to give Catalyst D. Catalyst D has
a dark grey appearance, a Pd content of 0.135 wt %, a Ag content of
0.135 wt %, and an average diameter of Pd particles of 3.1 nm.
Example 5
[0092] 30 ml of solution of PdCl.sub.2 in hydrochloride acid having
a Pd content of 10 mg/ml was diluted with 10 ml of de-ionized water
and then neutralized with 1 N NaOH solution to pH value of 5.0.
So-obtained solution was uniformly spray coated on 100 g of
Al.sub.2O.sub.3 carrier. The carrier was sufficiently wetted with
20 ml of 50% solution of isopropyl alcohol in water, and then
irradiated under vacuum with a .sup.60Co .gamma. radiation source
at a dose rate of 60 Gy/min for 12 h. The irradiated sample was
dried at 60.degree. C. for 12 hours, to give Catalyst E. Catalyst E
has a black appearance, a Pd content of 0.3 wt %, and an average
diameter of Pd particles of 4.7 nm.
Comparative Example 1
[0093] 17 ml of solution of PdCl.sub.2 in hydrochloride acid having
a Pd content of 2 mg/ml was diluted with 30 ml of de-ionized water
and then neutralized with 1 N NaOH solution to pH value of 3.0.
So-obtained solution was uniformly spray coated on 100 g of
Al.sub.2O.sub.3 carrier. The carrier was dried, calcined at
500.degree. C. for 8 hours to decompose the PdCl.sub.2, and then
reduced at 150.degree. C. under hydrogen gas flow for 2 h, to give
Catalyst F. Catalyst F has a light yellow appearance and a Pd
content of 0.034 wt %.
Comparative Example 2
[0094] 13.5 ml of solution of PdCl.sub.2 in hydrochloride acid
having a Pd content of 10 mg/ml was diluted with 30 ml of
de-ionized water and spray coated on 100 g of Al.sub.2O.sub.3
carrier. Then 10 ml of 1N NaOH solution was spray coated on the
carrier to fix the palladium salt. The carrier was dried and
calcined at 500.degree. C. for 8 hours to decompose the PdCl.sub.2,
to give Catalyst G. Catalyst G has a yellow appearance and a Pd
content of 0.135 wt %.
[0095] The above samples were characterized by X-ray photoelectron
spectroscopy (XPS), and the results are shown in Table 1 below. The
results of XPS show that after the radiation reduction, Catalysts A
to E of the Examples have surface Pd.sub.3d5/2 binding energy below
335.5 eV, indicating that the Pd is present in metal elementary
state. Catalysts F and G of the Comparative Examples have surface
Pd.sub.3d5/2 binding energy larger than 336.4 eV, indicating that
the Pd is present in oxidized state.
TABLE-US-00001 TABLE 1 XPS results of catalysts from the inventive
Examples and Comparative Examples catalyst BE of Pd.sub.3d5/2 (eV)
BE of Pd.sub.3d3/2 (eV) Example 1 A 335.4 340.9 Example 2 B 335.3
340.8 Example 3 C 334.9 340.3 Example 4 D 334.7 340.2 Example 5 E
335.4 340.8 Comparative F 336.9 342.1 Example 1 Comparative G 336.5
341.9 Example 2
[0096] The dispersion of Pd particles on the surface of the
Catalysts C, D, E and G was observed through a transmission
electron microscope (TEM), and the results are shown in FIG. 1. The
TEM results show that in the Catalysts C, D and E from the
Examples, Pd particles are uniformly dispersed on the carrier
surface, while in the Catalyst G from the Comparative Example, the
Pd particles on the surface exhibit agglomeration and sintering
phenomenon.
Example 6
[0097] The above Catalysts A, B and F were used in hydrogenation
test of a pyrolysis gas from an ethylene plant as follows. 1 ml of
each of the catalysts was loaded into a stainless steel tubular
reactor with an internal diameter of 7.8 mm. The atmosphere in the
reactor was replaced with nitrogen gas, then a feed gas, together
with hydrogen gas, was passed through the reactor. The feed gas had
a composition by mole of: 36.5% methane, 8% ethane, 38% ethylene,
10% propylene, 0.8% ethyne, 0.4% propyne, 0.2% propadiene, as well
as a minor amount of butenes, butadiene, pentanes, and the like,
and the hydrogen gas was used in an amount of about 16 mol %,
relative to the feed gas. The test was conducted at a space
velocity of 10000 h.sup.-1.
[0098] The above catalysts were evaluated with respect to their
performance in the selective hydrogenation for ethyne and propyne
propadiene (MAPD), and the conversions of hydrogenating ethyne into
ethylene and MAPD into propylene as well as corresponding
selectivity for individual catalysts at 80.degree. C. are shown in
Table 2 below. Ethyne conversion, ethylene selectivity, MAPD
conversion, and propylene selectivity are calculated as:
C 2 H 2 Conversion = ( C 2 H 2 ) i n - ( C 2 H 2 ) out ( C 2 H 2 )
i n .times. 100 ##EQU00001## C 2 H 4 Selectivity = ( C 2 H 4 ) out
- ( C 2 H 4 ) i n ( C 2 H 2 ) i n - ( C 2 H 2 ) out .times. 100
##EQU00001.2## MAPD Conversion = ( MAPD ) i n - ( MAPD ) out ( MAPD
) i n .times. 100 ##EQU00001.3## C 3 H 6 Selectivity = ( C 3 H 6 )
out - ( C 3 H 6 ) i n ( MAPD ) i n - ( MAPD ) out .times. 100
##EQU00001.4##
[0099] The experimental results indicate that, for the
hydrogenation of ethyne and the hydrogenation of MAPD, at similar
olefin selectivity, the catalysts prepared by the method comprising
the radiation reduction according to the invention exhibit much
higher activities (indicated by the conversions) than those of
Comparative Examples.
TABLE-US-00002 TABLE 2 Performance of some of the catalysts from
Examples and Comparative Examples in catalytic reaction Reaction
temperature: 80.degree. C. Ethyne Ethylene MAPD Propylene
Conversion Selectivity Conversion Selectivity Catalyst % % % %
Example 1 A 91.3 88.2 25.7 97.9 Example 2 B 64.9 89.8 13.3 99.1
Comparative F 46.0 88.8 3.4 74.0 Example 1
[0100] The above Catalysts C, D and G were used in a side-line
evaluation test in a C3 fraction liquid phase selective
hydrogenation industrial scale plant. A fixed bed reactor was used,
catalyst loading amount was 92 ml, reaction pressure was 2 MPa
(gauge), and space velocity was 70 h.sup.-1. The feed at the
reactor inlet comprised 2.3 mol % MAPD, 92.5 mol % propylene, and
5.2 mol % propane. Temperature at reactor inlet and H.sub.2/MPAD
ratio were adjusted to obtain a selectivity as high as possible,
provided that the MAPD was completely removed by the hydrogenation.
The calculations of MAPD conversion and propylene selectivity were
as described above.
[0101] The test results indicate that, for the liquid phase
selective hydrogenation of C3 stream, the catalysts prepared by the
method comprising the radiation reduction according to the
invention exhibit good selectivity and activity, with performance
being markedly superior to that of the catalyst of Comparative
Examples.
TABLE-US-00003 TABLE 3 Performance of some of the catalysts from
Examples and Comparative Examples in catalytic reaction Temperature
Propylene MAPD at Inlet H.sub.2/MAPD Selectivity Conversion
Catalyst .degree. C. mol/mol % % Example 3 C 34 1.32 83.25 100
Example 4 D 40 1.65 80.32 100 Comparative G 40 1.61 45.26 100
Example 2
Example 7
[0102] 5.25 ml of 2 mg/ml solution of Pd(NO.sub.3).sub.2 was mixed
with 6.0 ml of 3.5 mg/ml solution of AgNO.sub.3, and the mixture
was uniformly spray coated on 30 g of Al.sub.2O.sub.3 carrier,
followed by the spray coating of 6.0 ml of 0.5N NaOH solution. The
carrier was wetted with 10 ml of 50% solution of isopropyl alcohol
in water, and then irradiated under vacuum with a .sup.60Co .gamma.
radiation source at a dose rate of 30 Gy/min for 25 h. The
irradiated sample was washed with de-ionized water four times and
dried at 50.degree. C. for 12 h, to give Catalyst H. Catalyst H has
a Pd content of 0.035 wt % and a Ag content of 0.7 wt %.
Example 8
[0103] 6.0 ml of 3.5 mg/ml solution of AgNO.sub.3 was uniformly
spray coated on 30 g of Al.sub.2O.sub.3 carrier. After drying, the
carrier was calcined at 550.degree. C. for 8 h to decompose
AgNO.sub.3. 5.25 ml of 2 mg/ml solution of PdCl.sub.2 was adjusted
with 1 N NaOH solution to pH 3, and the resultant solution was
uniformly spray coated on the Ag-containing carrier. The carrier
was wetted with 10 ml of 30% solution of ethylene glycol in water,
and then irradiated under vacuum with a .sup.60Co .gamma. radiation
source at a dose rate of 30 Gy/min for 25 h. The irradiated sample
was washed with de-ionized water four times and dried at 50.degree.
C. for 12 h, to give Catalyst I. Catalyst I has a Pd content of
0.035 wt % and a Ag content of 0.7 wt %.
Example 9
[0104] 5.25 ml of 2 mg/ml solution of Pd(NO.sub.3).sub.2 was mixed
with 6.0 ml of 3.5 mg/ml solution of Pb(NO.sub.3).sub.2, and the
mixture was spray coated on 30 g of Al.sub.2O.sub.3 carrier,
followed by the spray coating of 6.0 ml of 0.5N NaOH solution. The
carrier was wetted with 10 ml of 50% solution of isopropyl alcohol
in water, and then irradiated under vacuum with a .sup.60Co .gamma.
radiation source at a dose rate of 30 Gy/min for 25 h. The
irradiated sample was washed with de-ionized water four times and
dried at 50.degree. C. for 12 h, to give Catalyst J. Catalyst J has
a Pd content of 0.035 wt % and a Pb content of 0.7 wt %.
Example 10
[0105] 5.25 ml of 2 mg/ml solution of Pd(NO.sub.3).sub.2 was mixed
with 3.0 ml of 3.5 mg/ml solution of Ag(NO.sub.3).sub.2 and 1.12 ml
of 2.70 mg/ml solution of Bi(NO.sub.3).sub.3, and the mixture was
spray coated on 30 g of Al.sub.2O.sub.3 carrier, followed by the
spray coating of 5.0 ml of 1N NaOH solution. The carrier was wetted
with 10 ml of 50% solution of isopropyl alcohol in water, and then
irradiated under vacuum with a .sup.60Co .gamma. radiation source
at a dose rate of 30 Gy/min for 40 h. The irradiated sample was
washed with de-ionized water four times and dried at 50.degree. C.
for 12 h, to give Catalyst K. Catalyst K has a Pd content of 0.035
wt %, a Ag content of 0.035 wt % and a Bi content of 0.01%.
Comparative Example 3
[0106] 5.25 ml of 2 mg/ml solution of Pd(NO.sub.3).sub.2 was mixed
with 6.0 ml of 3.5 mg/ml solution of AgNO.sub.3, and the mixture
was uniformly spray coated on 30 g of Al.sub.2O.sub.3 carrier. The
carrier was dried and then calcined at 550.degree. C. for 8 h, to
give Catalyst L. Catalyst L has a Pd content of 0.035 wt % and a Ag
content of 0.7 wt %.
Comparative Example 4
[0107] Commercial catalyst BC-H-20, available from Beijing Research
Institute of Chemical Industry, China Petroleum & Chemical
Corporation, was used. The catalyst contained Al.sub.2O.sub.3 as a
carrier, and Pd and Ag as active components, with Pd content being
0.035 wt % and Ag content being 0.7 wt %.
Example 11
[0108] The catalysts from Examples 7 to 10 and Comparative Examples
3 to 4 were used in post-hydrogenation simulation experiment of
ethylene as follows. 1 ml of each of the catalysts was loaded into
a stainless steel tubular reactor with an internal diameter of 7.8
mm. The atmosphere in the reactor was replaced with nitrogen gas,
and then a feed gas that simulated an overhead stream from a
deethanizer, together with hydrogen gas, was passed through the
reactor. The feed gas had a composition by mole of: 7% ethane,
92.64% ethylene, and 0.36% ethyne, and the molar ratio of hydrogen
gas to alkyne was 2:1. The test was conducted at a space velocity
of 10000 h.sup.-1.
[0109] The catalysts were evaluated with respect to their
performance in selective hydrogenation of ethyne, with Catalysts H,
I, J and K from the Examples being evaluated directly, and the
comparative Catalyst L and BC-H-20 being evaluated after having
been reduced in hydrogen gas flow at 150.degree. C. for 2 h. The
conversion and selectivity for hydrogenating ethyne to ethylene at
120-130.degree. C. achieved by each of said catalysts are given in
Table 4 below. The calculations of the conversion and selectivity
of ethylene are as described above.
TABLE-US-00004 TABLE 4 Results of post-hydrogenation simulation
experiment (averaged over 120-130.degree. C.) Catalyst Conversion
(%) Selectivity (%) Example 7 H 98.5 55.0 Example 8 I 98.5 62.3
Example 9 J 97.5 52.3 Example 10 K 95.5 70.0 Comparative L 99.0
28.2 Example 3 Comparative BC-H-20 99.0 38.3 Example 4
Example 12
[0110] 20 ml of 10 mg/ml solution of Pd(NO.sub.3).sub.2 was mixed
with 25 ml of 20 mg/ml solution of Cu(NO.sub.3), and the mixed
solution was spray coated on 100 g of alumina carrier, followed by
the spray coating of 10 ml of 3N NaOH solution. 20 ml of 50%
solution of isopropyl alcohol in water was added to the carrier
having Pd and Cu loaded thereon and uniformly mixed, and then the
excess solution was decanted. The mixture was irradiated under
vacuum with a .sup.60Co .gamma. radiation source at a dose rate of
30 Gy/min for 15 h. The irradiated sample was dried at 120.degree.
C. for 6 h, to give Catalyst M. Catalyst M has a Pd content of 0.20
wt % and a Cu content of 0.50 wt %, based on the total weight of
the catalyst.
Example 13
[0111] 20 ml of 10 mg/ml solution of Pd(NO.sub.3).sub.2 and 10 ml
of 10 mg/ml solution of AgNO.sub.3 was added into 20 ml distilled
water to prepare a mixed solution, and then the mixed solution was
spray coated on 100 g of alumina carrier, followed by the spray
coating of 10 ml of 3N NaOH solution. 20 ml of 50% solution of
isopropyl alcohol in water was added to the carrier having Pd and
Ag loaded thereon and uniformly mixed, and then the excess solution
was decanted. The mixture was irradiated under vacuum with a
.sup.60Co .gamma. radiation source at a dose rate of 30 Gy/min for
15 h. The irradiated sample was dried at 120.degree. C. for 6 h, to
give Catalyst N. Catalyst N has a Pd content of 0.20% and a Ag
content of 0.1%, based on the total weight of the catalyst.
Example 14
[0112] 20 ml of 10 mg/ml solution of Pd(NO.sub.3).sub.2, 10 ml of
10 mg/ml solution of Pb(NO.sub.3).sub.2 and 20 ml of 10 mg/ml
solution of Ca(NO.sub.3).sub.2 was mixed, and then the mixed
solution was spray coated on 100 g of alumina carrier, followed by
the spray coating of 10 ml of 3N NaOH solution. 20 ml of 50%
solution of isopropyl alcohol in water was added to the carrier
having Pd, Ag and Ca loaded thereon and uniformly mixed, and then
the excess solution was decanted. The mixture was irradiated under
vacuum with a .sup.60Co .gamma. radiation source at a dose rate of
30 Gy/min for 15 h. The irradiated sample was dried at 120.degree.
C. for 6 h, to give Catalyst O. Catalyst O has a Pd content of
0.20%, a Pb content of 0.1%, and a Ca content of 0.2%, based on the
total weight of the catalyst.
Example 15
[0113] 25 ml of 10 mg/ml solution of Pd(NO.sub.3).sub.2 and 5 ml of
10 mg/ml solution of Pb(NO.sub.3).sub.2 was added into 20 ml
distilled water to prepare a mixed solution, and then the mixed
solution was spray coated on 100 g of alumina carrier, followed by
the spray coating of 10 ml of 3N NaOH solution. 20 ml of 50%
solution of isopropyl alcohol in water was added to the carrier
having Pd and Pb loaded thereon and uniformly mixed, and then the
excess solution was decanted. The mixture was irradiated under
vacuum with a .sup.60Co .gamma. radiation source at a dose rate of
30 Gy/min for 15 h. The irradiated sample was dried at 120.degree.
C. for 6 h, to give Catalyst P. Catalyst P has a Pd content of
0.25% and a Pb content of 0.05%, based on the total weight of the
catalyst.
Comparative Example 5
[0114] A supported catalyst, Catalyst Q, was prepared according to
the method described in Chinese patent CN 1229312C. Catalyst Q has
a Pd content of 0.25% and a Pb content of 0.05%, based on the total
weight of the catalyst.
Example 16
[0115] Catalysts M, N, O, P and Q prepared in Examples 12 to 15 and
Comparative Example 5 were used in hydrogenation experiment of C4
fraction conducted in a fixed bed reactor. The loading amount of
the catalysts was 50 ml. Evaluation conditions were as follows:
reaction temperature at inlet: 40.degree. C., reaction pressure:
3.0 MPa (absolute), liquid hourly space velocity: 20-30 h.sup.-1,
hydrogen/unsaturated hydrocarbon ratio: 1.5 (mol/mol). The
evaluation experiment results are given in Table 5 below.
TABLE-US-00005 TABLE 5 Catalyst evaluation experiment results
Catalyst Alkane Content Alkane content Cata- Composi- LHSV prior to
Hydro- after Hydro- Example lyst tion h.sup.-1 genation, %
genation, % 12 M Pd 0.2% 26 70.32 >99 Cu 0.5% 13 N Pd 0.2% 28
70.76 >99 Ag 0.1% 14 O Pd 0.2% 30 70.03 >99 Pb 0.1% Ca 0.2%
15 P Pd 0.25% 28 70.28 >99 Pb 0.05% Compar- Q Pd 0.25% 20 72.21
>99 ative Pb 0.05% Example 5
[0116] The evaluation experiment results show that, compared to the
supported catalyst prepared by the conventional method, the
catalysts according to the invention prepared by means of radiation
reduction process exhibit higher catalytic activity in the olefin
hydrogenation and can be operated at higher olefin load. In order
to achieve the same hydrogenation effect, the catalysts according
to the invention may be used at markedly reduced amount and contain
markedly reduced amount of noble metal, compared to the catalyst
prepared by the conventional method.
Example 17
[0117] 70 ml aqueous solution of PbCl.sub.2 having a Pd content of
0.36 wt % and a pH value of 4.0 was prepared (during the
preparation, 1N NaOH solution was used to adjust the pH value). The
above PbCl.sub.2 solution was spray coated on 100 g of alumina
carrier. After left in stand for 20 min, a solution prepared from
20 ml of de-ionized water and 20 ml of isopropyl alcohol was poured
on the carrier having Pd supported thereon. After uniformly mixing,
the excess solution was decanted. The remaining mixture was
irradiated under vacuum with a .sup.60Co .gamma. radiation source
at a dose rate of 30 Gy/min for 15 h. The irradiated sample was
dried at 120.degree. C. for 6 h, to give Catalyst S. Catalyst S has
a Pd content of 0.25 wt %.
Example 18
[0118] 70 ml aqueous solution of PbCl.sub.2 having a Pd content of
0.36 wt % and a pH value of 4.0 was prepared (during the
preparation, 1N NaOH solution was used to adjust the pH value). The
above PbCl.sub.2 solution was spray coated on 100 g of alumina
carrier. After air drying, the carrier was dried in an oven at
120.degree. C. for 24 h. 70 ml Pb(NO.sub.3).sub.2 solution having a
Pb content of 0.72 wt % was prepared and spray coated on the
alumina carrier containing Pd. After left in stand for 20 min, a
solution prepared from 20 ml of water and 20 ml of isopropyl
alcohol was added to the carrier containing Pd. After uniformly
mixing, the excess solution was decanted. The remaining mixture was
irradiated under vacuum with a .sup.60Co .gamma. radiation source
at a dose rate of 30 Gy/min for 15 h. The irradiated sample was
dried at 120.degree. C. for 6 h, to give Catalyst T. Catalyst T has
a Pd content of 0.25 wt % and a Pb content of 0.50 wt %.
Example 19
[0119] Catalyst U was prepared by a procedure similar to that
described in Example 18, which has a Pd content of 0.25 wt % and a
Sn content of 0.40 wt %.
Example 20
[0120] Catalyst V was prepared by a procedure similar to that
described in Example 18, which has a Pd content of 0.25 wt %, a Sn
content of 0.40 wt % and a Mg content of 2.0 wt %.
Comparative Example 6
[0121] 70 ml aqueous solution of PbCl.sub.2 having a Pd content of
0.43 wt % and a pH value of 4.0 was prepared (during the
preparation, 1N NaOH solution was used to adjust the pH value). The
above PbCl.sub.2 solution was spray coated on 100 g of alumina
carrier. After air drying, the spray coated carrier was dried in an
oven at 120.degree. C. for 24 h. The resultant product was calcined
at 450.degree. C. for 8 h to decompose PdCl.sub.2, and then reduced
in hydrogen flow at 150.degree. C. for 2 h, to give Comparative
Catalyst W, which has a Pd content of 0.30 wt %.
Example 21
[0122] 100 ml of each of Catalysts S, T, U, V and W prepared in
Examples 17 to 20 and Comparative Example 6 was used in
hydrogenation experiment of C6-C8 middle distillate of pyrolysis
gasoline conducted in an adiabatic bed reactor. The middle
distillate used in the experiment had a diene value of 36 g
iodine/100 g oil and a gum content of less than 60 mg/100 ml oil.
Reaction conditions were as follows: hydrogen pressure: 2.8 MPa
(absolute); temperature at inlet: 45.degree. C.; volume ratio of
hydrogen to oil: 50:1; space velocity of total feed: 8 h.sup.-1.
The diene value of the oil was measured by malic anhydride method.
The evaluation results when the reaction had been conducted for 100
h are shown in Table 6 below.
TABLE-US-00006 TABLE 6 Performance of inventive catalysts and
comparative catalyst in hydrogenation of pyrolysis gasoline
Catalyst S T U V W Diene value of product 0.78 0.50 0.42 0.06 3.40
after hydrogenation (g iodine/100 g oil)
Example 22
[0123] Contrastive evaluations of hydrogenation performance at
relatively large space velocity were conducted by using Catalyst V
and comparative Catalyst W in a 100 ml adiabatic bed reactor. The
feed used in the evaluations was a C6-C8 middle distillate of
pyrolysis gasoline having a diene value of 36 g iodine/100 g oil
and a gum content of less than 60 mg/100 ml oil. Reaction
conditions were as follows: hydrogen pressure: 2.8 MPa; reaction
temperature: 45.degree. C.; volume ratio of hydrogen to oil: 50:1;
fresh oil space velocity: 8 h.sup.-1; recycling ratio: 2:1; total
space velocity: 24 h.sup.-1. The diene value of the oil was
measured by malic anhydride method. The evaluation results when the
reaction had been conducted for 100 h and 500 h are shown in Table
7 below.
TABLE-US-00007 TABLE 7 Hydrogenation performance of Catalyst V and
comparative Catalyst W at relatively large space velocity Catalyst
Comparative V Catalyst W Diene value of product 100 h 0.09 3.56
after hydrogenation 500 h 0.81 7.34 (g iodine/100 g oil)
Example 23
[0124] 100 ml of each of Catalysts S, T, U and V prepared in
Examples 17 to 20 was used in catalyst activity and selectivity
evaluation experiment conducted in an adiabatic bed reactor. The
feed used in the evaluations was a C6 to C8 middle distillate of
pyrolysis gasoline having a diene value of 14.11 g iodine/100 g
oil, an iodine value of 43.35 iodine/100 g oil, and a gum content
of less than 60 mg/100 ml oil. Reaction conditions were as follows:
reaction pressure: 2.8 MPa; reactor temperature at inlet:
40.degree. C.; volume ratio of hydrogen to oil: 80:1; fresh oil
space velocity: 8 h.sup.-1. The experimental results are shown in
Table 8 below.
TABLE-US-00008 TABLE 8 Hydrogenation performance of catalysts from
Examples 17 to 20 Item Catalyst S Catalyst T Catalyst U Catalyst V
Diene value of product 0.81 0.60 0.48 0.02 (g iodine/100 g oil)
Iodine value of product 23.40 21.36 22.91 22.31 (g iodine/100 g
oil)
[0125] The patents, patent applications and testing methods cited
in the specification are incorporated herein by reference.
[0126] While the invention has been described with reference to
exemplary embodiments, it will be understood by those skilled in
the art that various changes and modifications may be made without
departing from the spirit and scope of the invention. Therefore,
the invention is not limited to the particular embodiments
disclosed as the best mode contemplated for carrying out this
invention, but the invention will include all embodiments falling
within the scope of the pended claims.
* * * * *