Note: Descriptions are shown in the official language in which they were submitted.
CA 02218216 1997-10-14
SOLID CATALYST AND PROCESS FOR PRODUCING
UNSATURATED GLYCOL DIESTER USING THE SAME
FIELD OF THE INVENTION
The present invention relates to a palladium/-
tellurium solid catalyst and a process for producing an
unsaturated glycol diester using the catalyst. More
particularly, the present invention relates to a process in
which a conjugated diene is reacted with a carboxylic acid
and molecular oxygen in the presence of a solid catalyst
comprising palladium and tellurium as active ingredients
supported on a support with specific distributions to thereby
produce the corresponding unsaturated glycol diester.
BACKGROUND OF THE INVENTION
Unsaturated glycol diesters such as butenediol
diacetoxy ester are important intermediates in the production
of 1,4-butanediol, which is useful as a starting material for
engineering plastics, elastomers, elastic fibers, artificial
leathers, etc., and tetrahydrofuran, which is useful as a
high-performance solvent or a starting material for elastic
fibers.
Many processes have been proposed for producing such
butenediol diesters. Well known among these are processes in
which a solid catalyst comprising palladium and tellurium,
both supported on active carbon, is used to catalyze the
reaction of butadiene with a carboxylic acid and molecular
oxygen to produce a butenediol diester.
CA 02218216 1997-10-14
Specifically, one proposed method for producing an
unsaturated glycol diester comprises reacting molecular
oxygen and a carboxylic acid with a conjugated diene in the
presence of a solid catalyst containing palladium and at
least one of tellurium and selenium tsee JP-A-48-72090; the
term "JP-A" as used herein means an "unexamined published
Japanese patent application"). Another proposed method for
producing an unsaturated glycol ester comprises reacting
molecular oxygen and a carboxylic acid with a conjugated
diene in the presence of a solid catalyst cont~; n; ng
palladium, at least one of antimony and bismuth, and at least
one of tellurium and selenium (see JP-A-48-96513).
However, although the catalysts used in the above
proposed methods exhibit some catalytic activity, they are
not practical. In order to improve catalytic activity there
has been proposed a method for producing an unsaturated
glycol diester which comprises reacting molecular oxygen and
a carboxylic acid with a conjugated diene in the presence of
a solid catalyst cont~; n; ng palladium and at least one of
antimony, bismuth, selenium and tellurium, supported on a
support comprising active carbon having been processed with
nitric acid (see JP-A-49-11812). Another proposed method for
producing an unsaturated glycol diester comprises reacting
molecular oxygen and a carboxylic acid with a conjugated
diene in the presence of a solid catalyst in which palladium
and at least one of antimony, bismuth, selenium and tellurium
CA 02218216 1997-10-14
are supported on an active carbon support and the resulting
mixture is reduced, processed in gas containing molecular
oxygen at a temperature of 200~C or higher and again reduced
(see JP-A-50-4011). Yet another proposed method for
activating a catalyst comprises supporting palladium and at
least one of antimony, bismuth, selenium and tellurium on an
active carbon support. This catalyst is used for producing
an unsaturated glycol diester from a conjugated diene, a
carboxylic acid and molecular oxygen and is activated by a
process which comprises reducing the catalyst with methanol
gas and then oxidizing it with molecular oxygen, said
reduction and oxidation being performed at least once;
bringing the catalyst into contact with acetic acid and
molecular oxygen and reducing it with hydrogen gas (see JP-A-
55-3856).
In order to reduce the deterioration of catalytic
activity due to the lapse of time, there has been proposed a
catalyst for diacyloxy substitution of a conjugated diene
which comprises at least one noble metal selected from group
VIII of the periodic table of elements, and at least one
element selected from group IV, V or VI of the periodic table
of elements (with the proviso that zirconium, niobium and
molybdenum are excluded) supported on a support. The support
is silica having a specific surface area of 200 m2/g or
larger and an average pore diameter of 100 A or larger (see
JP-A-56-130232). There has also been proposed a method for
CA 02218216 1997-10-14
producing an unsaturated glycol diester which comprises
reacting a conjugated diene with a carboxylic acid and
molecular oxygen in the presence of a solid catalyst
comprising palladium and tellurium as active ingredients
supported on a solid support, characterized in that the
volume of pores having a pore radius of from S to 50 nm
accounts for at least 80% of the total volume of pores having
a pore radius of from 1.8 to 10,000 nm (see JP-A-8-3110).
Although the drawbacks of solid catalysts are
considerably mitigated by the various methods proposed in the
prior art, the proposed processes are still insufficient for
industrial production of target compounds. In addition,
since the proposed processes use palladium, an expensive
noble metal, it is necessary to increase the activity per
unit of palladium.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a
process for producing an unsaturated glycol diester in which
a catalyst-having higher activity than prior art catalysts is
used to react a conjugated diene with a carboxylic acid and
molecular oxygen to there~y provide an industrially
advantageous process for producing unsaturated glycol
diesters.
As a result of intensive investigations made by the
present inventors, it has been found that the distributions
of palladium and tellurium, supported as active ingredients
CA 02218216 1997-10-14
on a support, exert a considerable influence on catalytic
performance. The present invention has been completed based
on this finding.
According to one preferred aspect of the present
invention, a solid catalyst is provided which comprises an
inorganic porous material as a support and palladium and
tellurium supported thereon as active ingredients, wherein
said solid catalyst, when analyzed with an X-ray
microanalyzer (EPMA), has active-ingredient distributions in
which:
(a) at least about 80% of all palladium supported on the
catalyst and at least about 75% of all tellurium supported on
the catalyst are present in a surface layer of the support,
extending from an outer surface of the support to a depth
corresponding to about 30% of the radius of the support; and
(b) at least about 50% of the palladium present in the
surface layer of the support extending from the outer surface
of the support to a depth corresponding to about 30% of the
radius of the support, coexists with tellurium in a
tellurium/palladium atomic ratio of from about 0.15 to about
0.35.
According to another aspect of the present invention,
a process for producing an unsaturated glycol diester is
provided which comprises reacting a conjugated diene with a
carboxylic acid and molecular oxygen in the presence of the
above solid catalyst to thereby produce the corresponding
CA 02218216 1997-10-14
unsaturated glycol diester.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 (A) is a graphic representation of the average
distribution of palladium in the catalyst obtained in Example
1.
Fig. 1 (B) is a graphic representation of the average
distribution of tellurium in the catalyst obtained in Example
1.
Fig. 1 (C) is a histogram of palladium in the
catalyst obtained in Example 1.
Fig. 2 (A) is a graphic representation of the average
distribution of palladium in the catalyst obtained in
Comparative Example 1.
Fig. 2 (B) is a graphic representation of the average
distribution of tellurium in the catalyst obtained in
Comparative Example 1.
Fig. 2 (C) is a histogram of palladium in the
catalyst obtained in Comparative Example 1.
Fig. 3 (A) is a graphic representation of the average
distribution of palladium in the catalyst obtained in
Comparative Example 5.
Fig. 3 (B) is a graphic representation of the average
distribution of tellurium in the catalyst obtained in
Comparative Example 5.
Fig. 3 (C) is a histogram of palladium in the
catalyst obtained in Comparative Example 5.
CA 02218216 1997-10-14
Fig. 4 (A) is a graphic representation of the average
distribution of palladium in the catalyst obtained in Example
7.
Fig. 4 (B) is a graphlc representation of the average
distribution of tellurium in the catalyst obtained in Example
7.
Fig. 4 (C) is a histogram of palladium in the
catalyst obtained in Example 7.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
(I) Solid Catalyst for Acyloxy Substitution
In the solid catalyst for use in the present
invention, the palladium and tellurium supported as active
ingredients have respective distributions which satisfy
requirements (a) and (b) described above.
The distribution of an active ingredient supported on
a support in a solid catalyst is influenced by all the
factors involved in catalyst preparation (e.g., the
properties of the support, the kind of salt from which the
active ingredient is derived, the properties of a solution of
the salt, infiltration method, drying method, etc.). It is
therefore impossible to unconditionally specify a technique
capable of giving a specific distribution of a supported
ingredient. Even when any of the disclosed prior art
techniques is used for catalyst preparation, the obtained
catalysts do not have the same distribution of supported
ingredients as those described below in the Examples and
CA 02218216 1997-10-14
Comparative Examples. For example, catalysts prepared using
different starting tellurium salts differ considerably in the
distribution of supported tellurium, even when such catalysts
are prepared under the same conditions. For example, see
Example 4 and Comparative Example 10. In these examples in
which tellurium metal, as a tellurium salt, is used under the
conditions employed therein, the active ingredient is densely
deposited in a surface layer of the support. In addition,
catalysts prepared from the same starting materials (support,
palladium salt, and tellurium salt) can differ from each
other in the distribution of each supported ingredient merely
when produced using different drying methods (see Comparative
Example 10 and Examples 1 and 7) or produced under slightly
modified conditions (see Example 3 and Comparative Example
1) .
In view of the above, the present inventors have made
intensive investigations concerning the influence on
catalytic performance of the distributions of palladium and
tellurium supported as active ingredients in a solid
catalyst. As a result, they have found that the distribution
of ingredients in catalysts obtained, using an extremely
large number of combinations of catalyst preparation
conditions, is a crucially important factor which influences
the catalytic performance, although preferred catalyst
preparation conditions cannot be specified. They have
further found that a solid catalyst, in which supported
CA 02218216 1997-10-14
active ingredients have specific distributions, is
exceedingly active.
For determining the distributions of supported
ingredients, an EPMA is generally used. However, even
catalysts prepared by the same method do not have identical
distributions of supported ingredients. Even catalyst
products produced in the same lot have some degree of
fluctuation from particle to particle. It is therefore
difficult to accurately determine the distribution of a
supported ingredient based on an examination of only one
particle. In many particles, the distribution of a supported
ingredient fluctuates to some degree within each particle.
This does not mean that the distribution of a supported
ingredient in a catalyst particle varies merely as a function
of distance from the center of the particle, but rather that
in any section of a catalyst particle which, for example, is
spherical, different straight lines passing through the
center of the section have distributions of supported
ingredients which differ from one another along their
lengths. It is therefore difficult to accurately express the
distribution of a supported ingredient in a particle through
a mere examination along one line. In the case where no such
fluctuations are found in supported-ingredient distribution
in a catalyst particle, the distribution of the supported
ingredient in the particle can be represented by the results
of an examination of the distribution along any center line,
CA 02218216 1997-10-14
assuming the support is spherical. However, in the case of
supports of irregular shape, it is difficult to accurately
express the distribution of a supported ingredient from only
the results of an analysis along center lines through the
particle. Therefore, it is very difficult to obtain a
distribution of a supported ingredient which accurately
represents the distributions in all catalyst particles.
Under these circumstances, the present inventors used the
method described below to determine the distribution of a
supported ingredient which represents all distributions of
the ingredient in the catalyst.
Ten catalyst particles are arbitrarily selected. For
each selected particle, the section having the largest area
is ex~m;ned with an EPMA along the longest straight line
extending from one point to another on the circumference of
the section. Hereinafter, this straight line is referred to
as the ~major diameter line"; the length thereof is referred
to as the "diameter in the major diameter direction"; the
center of the major diameter line is referred to as the
"center in the major diameter direction"; and half of the
diameter is referred to as the "radius in the major diameter
direction.
For each selected particle, the longest straight line
which meets the major diameter line at right angles is also
examined by EPMA. Hereinafter, this straight line is
referred to as the "minor diameter line"; the length thereof
-- 10 --
CA 02218216 1997-10-14
is referred to as the ~'diameter in the minor diameter
direction"; the center of the minor diameter line is referred
to as the ~center in the minor diameter direction"; and half
of the diameter is referred to as the "radius in the minor
diameter direction". The major and minor diameter lines are
each examined by EPMA at intervals of 20 ~m. The results
obtained are corrected using equations (1) to (5), which will
be described later. Thus, supported-ingredient distributions
for ten major diameter lines and supported-ingredient
distributions for ten minor diameter lines are obtained. In
the case where the support is spherical, the section of the
particle is examined only along a major diameter line, based
on the assumption that the support is a true sphere. The
supported-ingredient distribution determined from the results
is regarded as being representative of all distributions in
the catalyst. In the case where the support is cylindrical,
the axis (the major-diameter-direction center line in a
rectangular section) is regarded as a major diameter line and
a straight-line which meets the major diameter line at its
center at right angles is regarded as the minor diameter
line, based on the assumption that the support is a true
cylinder. In the case of a support of any other shape, the
section is regarded as an ellipse having its major axis and
minor axis equal to the respective major diameter line and
minor diameter line of the section, and the solid body formed
by rotating the ellipse about the major axis is regarded as
CA 02218216 1997-10-14
the shape of the catalyst particle. In addition, with
respect to the supported-ingredient distributions along the
major diameter line, the positions of both ends of the major
diameter line (which are located on the surface of the
catalyst particle) are each taken as 0% and the position of
the center of the major diameter line is taken as 100%, to
determine the positions (%) of the individual examination
sites. Furthermore, the major diameter lines for each of the
ten particles is divided at its center into two parts,
thereby obtaining supported-ingredient distributions for
twenty major-diameter-line radii. The twenty distributions
are averaged with respect to each position (%) to thereby
obtain an average supported-ingredient distribution for the
major-diameter-line radii. In a similar manner, supported-
ingredient distributions for the twenty minor-diameter-line
radii and an average supported-ingredient distribution for
the minor-diameter-line radii are determined.
For the actual determination of distributions by
EPMA, it is- preferred to employ the ZAF correction method.
The ZAF correction method is a technique for deter~ining the
correction factor for atomic number effect (Z), absorption
effect (A), and fluorescent excitation effect (F).
Specifically, the f~F in the following equation is
determined:
Cu~k/Cstd = (Iunk/Istd)xf~Fxf other ( 1 )
wherein Cunk is the concentration of an element in the
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CA 02218216 1997-10-14
catalyst being examined, Cstd is the concentration of the
element in a standard sample, IUnk is the found intensity of
the element in the catalyst, Istd is the found intensity of
the element in the standard sample, fzAF is the correction
factor obtained by the ZAF correction method, and f other is
other correction factors.
This correction method is described in detail in, for
example, Hiroyoshi Soejima, "Electron Beam Microanalysisl',
Nikkan Kogyo Shinbun-sha. In the case of porous support
materials, such as in the catalysts of the present invention,
fOther is not negligible because of the density effect, etc.
Therefore, the standard sample for use in ex~mining such a
porous catalyst is preferably one consisting of the same
support as that of the catalyst being examined and an active
ingredient supported thereon homogeneously in a known
concentration. The term llhomogeneously" as used above means
that the active ingredient is homogeneously distributed in
the region where incident electrons diffuse, the region where
specific X rays generate, and the passageways through which
the X rays exit, on the order of about 10 nm; namely, the
whole standard sample is homogeneous on the order of a
nanometer. However, since such a standard sample is
difficult to prepare, the present inventors used a standard -
sample containing palladium metal for determining the
distribution of palladium in the catalyst, tellurium metal
- 13 -
CA 02218216 1997-10-14
for determining the distribution of tellurium in the
catalyst, and a support on which no active ingredient is
supported as a standard sample for the elements constituting
the support. The supported-ingredient distributions were
measured by the ZAF method and determined through the
following calculations. In the case where the catalyst
particle is spherical, the palladium concentration IrW (wt%)
at each examination site is determined using the following
equations:
Vfr = r~3-(r-20)~3 (2)
WCalC = ~ ( Irxvfr ) /~ Vfr
fwt = (Wanlxn)/(total of the Wcalc values for all particles
examined)
IrW = Irxfwt
wherein Vfr is the volume correction factor for each
examination site; r is the distance (~m) from the center of
the straight line along which examination was made to an
ex~min~tion site, provided that r is regarded as 20 when
r<20; WCalc is the palladium concentration (wt~) in each
sample determined from the results of an EPMA ~X~inAtion; Ir
is the palladium concentration (wt%) at each ex~min~tion site
determined by the ZAF correction method for each sample; ~ is
total over the range of the diameter of each straight line
along which an ~X~m; nation was made; fWt is the supporting
percentage correction factor, and corresponds to f other in
- 14 -
CA 02218216 1997-10-14
equation (1); Wanl is the palladium supporting percentage
(wt%) of the catalyst; n is the number of samples examined;
and IrW is the corrected palladium concentration (wt%) at
each examination site in each sample.
In the case of cylindrical catalyst particles, the
following equations (2-bl) and (2-b2) are used in place of
the above equation (2) for the major diameter direction and
minor diameter direction, respectively, to determine the
respective values of Vfr. From each Vfr value, fWt is
determined using equations (3) and (4). The average of the
two values of fWt thus obtained is used as the fWt of the
catalyst to calculate IrW using equation (5).
Vfr = 1 (2-bl)
Vfr = r~2-(r-20)~2
provided that r=20 when r<20. (2-b2)
In the case of supports of other shapes, equation (2-
c) is used in place of equations (2-bl) and (2-b2).
Otherwise, the calculations for supports of other
shapes are made in the same manner as in the case of
cylindrical supports.
Vfr = (ra~xrbl~2)-(ra2xrb2~2) (2-c)
When the above equation is used for a calculation for
the major diameter direction, ra, is the distance (~m)
between the center of the major-diameter-direction straight
line along which ex~m;nation was made and an ex~min~tion
CA 02218216 1997-10-14
site, and ra2, rb1, and rb2 are determined using the following
equations.
ra2 = ral 20
provided that ra1=20 when ra1<20 (2-c-al)
rbl = (ra1/Da)xDb (2-c-a2)
rb2 = (ra2/Da)XDb (2-c-a3)
When equation (2-c) is used for a calculation for the
minor diameter direction, rb1 is the distance (~m) between
the center of the minor-diameter-direction straight line
along which examination was made and an examination site, and
rb2, ral, and ra2 are determined using the following equations.
rb2 = rb1 20
provided that rbl=20 when rbl<20 (2-c-bl)
ral = (rbl/Db)XDa (2-c-b2)
ra2 = (rb2/Db)XDa (2-c-b3)
In the above equations, Da is the length (~m) of the major
diameter line, and Db is the length (~m) of the minor
diameter line.
With respect to tellurium, an average distribution
along the radii is determined in the same manner as described
above for palladium.
The proportion of each active ingredient present in
the surface layer of the support, extending from the support
surface to a depth corresponding to about 30% of the radius
of the support, to the total amount of the active ingredient
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CA 022l82l6 l997- lO- l4
supported in the catalyst was calculated as follows from the
average supported-ingredient distribution along the radii
determined by the method described above. In the case where
the solid catalyst is spherical, the proportion of the
palladium present in the range of from r1 to r2, in terms of
distance from the catalyst surface, to all palladium
supported in the catalyst, Cra (%), is determined using the
following equations:
Vfr = (R-rl)~3-(R-r2)~3 (6)
Cr = ( IrwXVfr/ ( ~ ( IrWXVfr ) ) ) x l O 0 ( 7 )
Cra = (total of the Cr values for all samples)/n (8)
wherein Vfr is volume correction factor for each examination
site; R is radius; Cr is the proportion (%) of the palladium
present in each sample in the range of from rl to r2, in
terms of distance from the catalyst surface, to all palladium
contained in the catalyst; IrW is the corrected palladium
concentration (wt%) at each examination site in each sample;
~ is total over the range from the catalyst surface to the
center of each sample; and n is the number of samples.
Consequently, the proportion of the palladium
supported in the range from the catalyst surface to the depth
corresponding to about 30% of the radius, to all palladium,
Cr30 (%), is defined as follows.
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CA 02218216 1997-10-14
Cr30 = (total of the Cra values for all examination sites in
the range of from a depth of 0% to a depth of about
30~) (9)
For a catalyst which is not spherical, Cr30 is determined for
each of the average distributions for major-diameter-line
radii and the average distributions for minor-diameter-line
radii, and the average thereof is taken as the Cr30 of the
catalyst. In the case of cylindrical supports, equation (6-
bl) is used in place of equation (6) to calculate the average
supported-ingredient distribution for the major-diameter-line
radii, while equation (6-b2) is used in place of equation (6)
to calculate the average supported-ingredient distribution
for the minor-diameter-line radii.
Vfr = 1 (6-bl)
Vfr = (R-rl)~2-(R-r2)~2 (6-b2)
In the case of supports of any other shape, equation
(6-cl) is used in place of equation (6) to calculate the
average supported-ingredient distribution for major-diameter-
llne radll:
Vfr = ((R-r1)x(R~-rl')~2)-((R-r2)x(R~-r2')~2) (6-cl)
wherein R' is the radius of minor diameter line; rl' =
(rl/R)xR'; and r2' = (r2/R)xR'.
For the calculation of the average supported-
ingredient distribution for minor diameter lines, equation
(6-c2) is used in place of equation (6):
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CA 02218216 1997-10-14
Vfr = ((R-rl)~2x(R'-rl'))-((R-r2)~2x(R'-r2')) (6-c2)
wherein R' is the radius of major diameter line; rl' =
(r1/R)xR'; and r2' = (rz/R)xR'.
With respect to tellurium, the value of Cr30 is
determined in the same manner as described above for
palladium.
For the active ingredients supported in the range
from the catalyst surface to a depth corresponding to about
30% of the radius, the tellurium/palladium atomic ratio, Xr,
for each examination site in each sample is determined using
the following equation:
Xr = (Irw(Te)/l27.6l)/(Irw(pd)/lo6-4) (10)
wherein IrW(Te) is the corrected tellurium concentration (wt%)
for each ex~mination site in each sample, and IrW(pd) is the
corrected palladium concentration (wt%) for each examination
site in each sample.
Consequently, the proportion, Ctp (%), of the
palladium which has been supported on the layer extending
from the catalyst surface to a depth corresponding to about
30% of the radius, and which has a tellurium/palladium atomic
ratio Xr in the range of from about O.lS to about 0.35, to
all the palladium supported on that layer, is determined
using the following equation.
C~p = ((total, in all examination radii, of Cr wherein the
palladium present in the layer extending from a depth
-- 19 --
CA 02218216 1997-10-14
corresponding to 0% of the radius to a depth
corresponding to about 30% of the radius has an Xr of
from about 0.15 to about 0.35)/((major-diameter-
direction Cr30 x n)+(minor-diameter-direction Cr30 x
n)))xlO0 (11)
In the case of spherical catalyst particles, however, the
following equation (11') is used in place of equation (11)
for determining the Ctp.
Ctp = ((total, in all examination radii, of Cr wherein the
palladium present in the layer extending from a depth
corresponding to 0% of the radius to a depth
corresponding to about 30% of the radius has an Xr of
from about 0.15 to about 0.35)/(Cr30 x n))xlO0
(11')
Although reasons explaining the high activities of
catalysts having specific supported-ingredient distributions
according to the present invention are not known, the
following explanations are possible. The reaction process
can be divided into the following steps: (1) substrates enter
pores of the catalyst; (2) the substrates diffuse within the
pores; (3) the substrates are adsorbed onto active sites in
the pores where active ingredients are supported; (4) a
reaction occurs at the adsorption sites; (5) the reaction
products are desorbed from the active sites; (6) the reaction
products diffuse within the pores; and (7) the reaction
- 20 -
-
CA 02218216 1997-10-14
products are released from the pores. In the case where the
time required for step (2) or for steps (2) and (6) is longer
than that required for the other steps, higher reaction rates
are attained when the distance over which the substrates or
reaction products must move within the pores is shorter, that
is, when a greater proportion of the active ingredients are
present in areas close to the inlets of the catalyst pores (a
surface layer portion of the catalyst). However, when that
distance becomes shorter than a given value, the difference
between the time required for step (2), or for steps (2) and
(6), and the time required for the other steps becomes
smaller and the influence on reaction rate is reduced.
Consequently, the area where active ingredients are present
in a large amount need not be limited to the surface of the
support, and therefore the active ingredients may be present
in a layer extending to some depth. Specifically, a catalyst
in which at least about 80% of all supported palladium and at
least about 75% of all supported tellurium are present in a
surface layer extending from the outer surface of the support
to a depth corresponding to about 30% of the radius, as in
the present invention, has high activity.
For the acyloxy substitution reaction, the proportion
of tellurium to palladium supported as active ingredients is
important. If the proportion of supported tellurium to
supported palladium is too small, palladium is released from
the support and enters the reaction mixture during the
CA 02218216 1997-10-14
acyloxy substitution reaction. If the proportion of
tellurium is too large, tellurium enters the reaction
mixture. In either case, the catalytic activity is reduced.
Generally, it is particularly preferred that the proportion
of supported tellurium to supported palladium in a catalyst
be from about 0.05 to about 5.0 in terms of the ratio of
number of gram-atom of supported tellurium atoms per gram-
atom of supported palladium. It should however be noted that
in many catalysts, the supported-palladium distribution and
the supported-tellurium distribution are not completely the
same, but differ from each other in some degree. Therefore,
the supported palladium and tellurium are not present in a
constant atomic ratio. When the relationship between the
amount of palladium and the tellurium/palladium atomic ratio
in a catalyst is expressed by means of a histogram and the
histogram distribution has too great a width, then the
catalyst is undesirable because palladium or tellurium will
be released therefrom as described above. However, an
exceedingly narrow histogram distribution is not essential.
The acyloxy substitution reaction according to the present
invention can be satisfactorily conducted even when the
tellurium/palladium atomic ratio varies to some degree.
Therefore, the histogram distribution may have some degree of
width.
However, the importance of the tellurium/palladium
atomic ratio does not apply to the whole catalyst. It is
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CA 02218216 1997-10-14
only the active ingredients present in the layer extending
from the support surface to a depth corresponding to about
30% of the radius, as in the present invention, which are
limited in the width of the histogram distribution.
Specifically, a catalyst in which at least about 50% of the
palladium, present in a surface layer of the support
extending from the support surface to a depth corresponding
to about 30~ of the radius of the support, coexists with
tellurium in a tellurium/palladium atomic ratio of from about
0.15 to about 0.35 was found to have exceedingly high
activity.
The support employed in the catalyst for the acyloxy
substitution of a conjugated diene according to the present
invention is preferably an inorganic, porous material which
undergoes substantially no change under the reaction
conditions. Preferred examples of supports include active
carbon, oxides such as silica, alumina, titania, and
zirconia, and mixed oxides thereof. Especially preferred is
silica. The support is not particularly limited in shape.
However, support particle diameters which are too large
result in reduced catalyst particle surface areas, while
support particle diameters which are too small result in
increased pressure losses in a packed catalyst layer. The
preferred industrially effective range of support size is
therefore from about l to about 8 mm. The support is
preferably porous, and preferably has an average pore
-
CA 02218216 1997-10-14
diameter of from about 10 to about 50 nm.
Methods for supporting active ingredients on an
inorganic porous material in the catalyst of the present
invention are not particularly limited, as long as the active
ingredients supported on the catalyst have the specific
distributions described above. Some preferred techniques for
supporting active ingredients on the surface of a catalyst
according to the invention include: a method in which an
aqueous solution containing the active ingredients is
infiltrated into a porous support in the presence of urea
(see JP-A-51-40392); a method in which an inorganic support
is impregnated with a solution-containing polyethylene glycol
and the active ingredients (see JP-B-55-33381; the term "JP-
B" as used herein means an "examined Japanese patent
publication"); a method in which a hydrocarbon is added to a
solution of salts of the active ingredients in at least one
solvent selected from ketones, esters, and alcohols to form a
resultant mixed solution having lower polarity than acetone,
which is then infiltrated into an inorganic porous support
(see JP-B-57-5578); and a method in which a solution of the
active ingredients is sprayed over a heated support to
deposit the active ingredients on the surface of the support
(see JP-A-3-293036). Other preferred techniques comprise
supporting the active ingredients around the surface of a
support, for example a method in which small amounts of the
active ingredients are first supported on a support, and then
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CA 02218216 1997-10-14
further amounts of the active ingredients are added, to
result in a necessary amount of the active ingredients being
supported on the support (see JP-B-54-8638). Still other
techniques comprise those in which the active ingredients are
supported in regulated positions, such as the competitive
adsorption method (see, e.g., JP-B-52-23920 and JP-B-52-
30475). Other preferred examples of techniques in which the
active ingredient is supported in regulated positions
include: a method comprising adsorbing the active ingredients
onto a surface layer of a support under conditions in which
tenacious adsorption occurs, followed by drying the support
to fix the active ingredients; a method comprising
infiltrating a solution of the active ingredients into a
support under conditions in which the active ingredients are
not adsorbed onto the support, followed by rapidly drying the
support to thereby deposit large amounts of the active
ingredients on a surface layer of the support; and a method
comprising hydrophobizing a support, for example by a surface
treatment which comprises infiltrating an aqueous solution
containing the active ingredients into only a surface layer
of the support, and then drying the support to fix the active
ingredients. Any of the above methods may preferably be used
to support the active ingredients on a support. Although the
mechanism by which specific distributions of active
ingredients are produced is unclear, one particularly
preferred method for supporting the active ingredients on a
- 25 -
CA 02218216 1997-10-14
support comprises infiltrating an aqueous solution containing
the active ingredients into a support and then drying the
support. Drying may preferably be conducted in a kiln,
wherein hydrogen gas is introduced while fluidizing the
catalyst to thereby conduct drying and reduction
simultaneously. Alternatively, the impregnated support may
preferably be dried with superheated steam.
The catalyst with the active ingredients supported
thereon is preferably reduced prior to use. It may also be
preferred to subject the catalyst to drying or burning prior
to reduction, for example in circumstances where the catalyst
has been dried insufficiently or where it is desired to
decompose a supported salt to some degree prior to use. Salt
decomposition may be preferred where one of the ingredients
is a nitrate, to thereby reduce the amount of NOx generated
upon reduction. Salt decomposition may also be preferred to
reduce heat generation during reduction. The drying or
burning of the catalyst may be conducted repeatedly if
desired.
Methods for drying, burning, and reduction are not
particularly limited, so long as they do not inhibit the
attainment of the specific supported-ingredient distributions
in the catalyst according to the present invention.
Preferred examples of drying methods include: fluidized-bed
vacuum drying using a rotary evaporator or a conical blender;
stationary drying using a vacuum dryer, a stacked-shelf type
- 26 -
CA 02218216 1997-10-14
dryer, or the like; fluidized-bed drying using a kiln dryer
or the like; and drying in a stream of nitrogen, air,
hydrogen, steam, etc. Any of these preferred drying methods
may be used. Preferred examples of burning methods include:
a method comprising heating the catalyst in a stream of,
e.g., nitrogen, air, or a mixture thereof using a fixed bed
or a fluidized bed, such as in a kiln; and a method in which
the catalyst is heated without passing a gas therethrough.
Either of these preferred burning methods may be used.
Preferred examples of reduction methods include: vapor-phase
reduction with, e.g., hydrogen gas or methanol gas; and
liquid-phase reduction with a liquid such as hydrazine or
formalin.
A palladium compound is preferably used for preparing
the catalyst. Preferred examples thereof include palladium
oxide; palladium salts of inorganic acids, such as palladium
nitrate, palladium chloride, and palladium sulfate; palladium
salts of organic acids, such as palladium acetate; complex
palladium salts such as tetraamminepalladium chloride; and
organometallic palladium compounds such as palladium
acetylacetonate. It may also be preferred to use palladium
metal. The concentration of palladium supported on the
support is preferably within the range of from about 0.1 to
about 20% by weight of the catalyst, more preferably from
about 0.5 to about 10% by weight of the catalyst. If the
palladium concentration is below the lower limit of about
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CA 02218216 1997-10-14
0.1% by weight, the catalyst is reduced in activity per unit
weight thereof and may be unsuitable for practical use. If
the palladium concentration exceeds the upper limit of about
20% by weight, not only is the catalyst reduced in activity
per unit of palladium, but the catalyst cost is also
increased because palladium is expensive. Therefore, the use
of either too much or too little palladium is economically
undesirable.
A tellurium compound is preferably also used for
preparing the catalyst. Preferred examples thereof include
tellurium halides such as tellurium(II) chloride and
tellurium(IV) chloride; tellurium oxides such as
tellurium(IV) oxide and tellurium(VI) oxide; telluric acid
(H6TeO6) and salts thereof; tellurous acid (H2TeO3) and salts
thereof; tellurium metal; sodium hydrogen telluride (NaHTe);
and organotellurium compounds such as diphenyl ditelluride
([PhTe]2). The total amount of tellurium supported in the
catalyst is not particularly limited, as long as at least
about 50% of the palladium, present in a surface layer of the
support extending from the outer surface of the support to a
depth corresponding to about 30% of the radius of the
support, coexists with tellurium in a tellurium/palladium
atomic ratio of from about 0.15 to about 0.35, as described
above.
(II) Production of Unsaturated Glycol Diester
The conjugated diene, e.g., butadiene, used as a
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CA 02218216 1997-10-14
starting material in producing an unsaturated glycol diester
using the catalyst described above, is not necessarily pure.
It may contain an inert gas such as nitrogen; a saturated
hydrocarbon, e.g., methane, ethane, or butane; or an
unsaturated hydrocarbon, e.g., butene. Besides butadiene,
examples of other preferred conjugated dienes include
isoprene, alkyl-substituted butadienes such as 2,3-
dimethylbutadiene and piperylene, and cyclic dienes such as
cyclopentadiene.
Preferred examples of the carboxylic acid used as the
other starting material include lower monocarboxylic acids
such as acetic acid, propionic acid, and butyric acid.
Acetic acid is particularly preferred due to its high
reactivity and low cost. The carboxylic acid may preferably
serve not only as a starting material, but also as a solvent.
It may also be preferred to carry out the reaction in the
presence of an inert organic solvent such as a saturated
hydrocarbon or an ester. However, it is preferred that the
carboxylic acid starting material comprises at least about
50% by weight of the solvent in which the reaction is
conducted. Furthermore, the amount of carboxylic acid is
preferably in the range from the stoichiometric amount to
about 60 mol per mol of the conjugated diene.
The molecular oxygen used in the process of the
present invention need not be pure oxygen, and may preferably
be diluted with an inert gas, e.g., nitrogen. For example,
- 29 -
CA 02218216 1997-10-14
air may be used as the molecular oxygen. The amount of
oxygen is not particularly limited as long as it is not less
than the stoichiometric amount. However, from the standpoint
of safety in industrial production, the amount of oxygen is
preferably in a range which does not result in an explosive
composition.
The process of the present invention, in which a
conjugated diene is reacted with a carboxylic acid and
molecular oxygen to produce the corresponding unsaturated
glycol carboxylic diester, can be carried out either batch-
wise or continuously. Although the reaction may preferably
be carried out by a fixed-bed, fluidized-bed, or suspension
type process, the fixed-bed type process is more preferred as
an industrial process. The reaction is preferably conducted
at a temperature of about 20~C or higher. However, a more
preferred reaction temperature range is from about 40 to
about 120~C from the standpoints of reaction rate, by-product
generation, etc. The reaction may be preferably conducted
either at ordinary pressure or at elevated pressure.
Although elevated pressure is more preferred from the
standpoint of heightening the reaction rate, it also results
in increased equipment cost. Therefore, the most preferred
pressure range is from about atmospheric pressure to about
100 kgf/cm2.
Preferred embodiments of the present invention will
now be described below in more detail by reference to
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CA 02218216 1997-10-14
Examples. ~owever, the invention should not be construed as
being limited to these preferred Examples. To express the
distributions of supported active ingredients in the
catalysts of the following Examples and Comparative Examples,
the following terms are used. The proportion of active
ingredient present in the surface layer of the support
extending from the outer surface of the support to a depth
corresponding to about 30% of the radius, to the total amount
of the active ingredient supported in the catalyst, i.e., the
proportion determined using equation (9), is referred to as
~proportion A~ (%); while the proportion of palladium which
has been supported on the surface layer of the catalyst
extending from the outer surface of the support to a depth
corresponding to about 30% of the radius, and which has a
tellurium/palladium atomic ratio of from about 0.15 to about
0.35, to all the palladium present in that surface layer,
i.e., the proportion determined using equation (11), is
referred to as "proportion B" (%).
The results of the reactions are described using the
following terms. The term "activity" is used to express the
total number of millimoles of 3,4-diacetoxy-1-butene, 3-
hydroxy-4-acetoxy-1-butene, 1-acetoxycrotonaldehyde, 1,4-
diacetoxy-2-butene (1,4-DABE), l-hydroxy-4-acetoxy-2-butene,
1,4-dihydroxy-2-butene, diacetoxyoctatriene, and
triacetoxybutene, among various other reaction products,
yielded per kg of catalyst per hour. The term "1,4-DABE
CA 02218216 1997-10-14
selectivity" means the proportion (mol%) of 1,4-diacetoxy-2-
butene which is produced, relative to the total amount of the
above-listed reaction products and other reaction products
such as furan, acrolein, monoacetoxybutene, butanol, and
monoacetoxy-1,3-butadiene.
EXAMPLE 1
Into a 50-ml measuring flask was introduced 0.843 g
of tellurium metal (manufactured by NE Chemcat Corp.). 20 g
of 35 wt% aqueous nitric acid solution was added to dissolve
the metal. To this solution was added 27.05 g of 10.0 wt%
aqueous palladium nitrate solution (manufactured by NE
Chemcat Corp.), followed by sufficient 35 wt% aqueous nitric
acid solution to adjust to the total volume of the contents
to 50 ml. To the resultant solution was added 25.05 g of a
spherical silica support (manufactured by Fuji Silysia
Chemical, Ltd., Japan and sold under the trademark, CARiACT-
Q-15; particle diameter, 1.7-3.36 mm; hereinafter referred to
as "CARiACT-Q-15"). After the support was immersed in the
solution at-room temperature for 1 hour, the mixture was
filtered to remove the solution. Thereafter, the excess
solution was removed from the support with a centrifuge to
obtain an impregnated support in an amount of 56.05 g. A
28.0-g portion of the thus-obtained catalyst was placed in a
horizontal kiln (inner diameter, 3 cm; effective sectional
area, 7.1 cm2). The kiln contents were heated from room
temperature to 150~C over a period of 1 hour and then kept at
- 32 -
CA 02218216 1997-10-14
150~C for 2 hours, while rotating the kiln at 30 rpm and
passing hydrogen gas therethrough at a rate of 4.2 Nl/min.
Thus, drying and reduction were conducted simultaneously.
The contents were then cooled in a nitrogen stream to obtain
13.39 g of an activated catalyst. The activated catalyst
contained 5.0 wt% palladium and 1.56 wt% tellurium.
4 g of the catalyst was then packed into a stainless-
steel reaction tube having an inner diameter of 12 mm
(effective sectional area, 1.005 cm ). 1,3-Butadiene, acetic
acid, and nitrogen containing 6% oxygen were introduced into
the reaction tube at rates of 0.15 mol/hr, 2.5 mol/hr, and
100 Nl/hr, respectively, and the reaction was continuously
conducted for 7 hours at a pressure of 60 kgf/cm2 and a
temperature of 80~C. A portion of the reaction mixture
withdrawn between 4 hours and 5 hours after initiation of the
reaction, and a portion of the reaction mixture withdrawn
between 6 hours and 7 hours after initiation of the reaction,
were quantitatively analyzed by gas chromatography to
determine the reaction products. The results of these
analyses were averaged to determine the activity and
selectivity, and are shown in Table 1.
Distributions of supported ingredients were
determined as follows. Ten catalyst particles were
arbitrarily selected from the catalyst obtained above. With
respect to each selected particle, the section having the
largest area was examined with an EPMA (JXA-8600M,
CA 02218216 1997-10-14
manufactured by JEOL Ltd., Japan) along the longest straight
line extending from one point to another on the circumference
of the section, the examination being conducted at intervals
of 20 ~m along this line. With respect to each examination
site, ZAF correction and supporting percentage correction
were conducted. Thus, supported-ingredient distributions for
20 radii and an average supported-ingredient distribution for
the radii were determined with respect to each of palladium
and tellurium. Values of proportion A were determined from
the average supported-ingredient distributions for the radii,
while proportion B was determined from the supported-
ingredient distributions for the 20 radii. The results
obtained are shown in Table 1. Figs. 1 (A) to (C) show
supported-ingredient distributions and a histogram, with
respect to the tellurium/palladium atomic ratio, of palladium
present in a layer ranging from the surface of the catalyst
particles to a depth of 30%.
EXAMPLE 2
A catalyst was prepared in the same manner as in
Example 1, except that the flow rate of hydrogen gas during
the drying and reduction step was changed to 0.26 Nl/min.
The diacetoxylation reaction of butadiene and the
determination of supported-ingredient distributions were
conducted in the same manner as in Example 1. The results
obtained are shown in Table 1.
- 34 _
CA 02218216 1997-10-14
EXAMPLE 3
Into a 50-ml measuring flask was introduced 1.244 g
of tellurium dioxide (manufactured by Mitsuwa Chemical Co.,
Ltd., Japan). 28 g of a 35 wt% aqueous nitric acid solution
was added to dissolve the tellurium compound. To this
solution was added 20.89 g of 10.0 wt% aqueous palladium
nitrate solution, followed by sufficient 35 wt% aqueous
nitric acid solution to adjust the total volume to 50 ml. To
the resultant solution was added 20.81 g of a spherical
silica support (manufactured by Shell Chemical Co., Ltd.,
Japan; sold under the trademark, S980G; particle diameter,
2.4-3.4 mm). After the support was immersed in the solution
at room temperature for 1 hour, the mixture was filtered to
remove the solution. Thereafter, the excess solution was
removed from the support with a centrifuge to obtain an
impregnated support in an amount of 49.10 g. The catalyst
was packed into a pyrex glass tube having an inner diameter
of 2.5 cm (effective sectional area, 4.9 cm2). The catalyst
was dried first at 90~C for 2 hours and then at 150~C for 2
hours, while passing nitrogen gas through the tube at a rate
of 6.7 Nl/min. Subsequently, while introducing hydrogen in
place of nitrogen at a rate of 0.42 Nl/min, the dried
catalyst was heated at a rate of 50~C/hr to 400~C and kept at
this temperature for 2 hours. The contents of the tube were
then cooled in a nitrogen stream to obtain 22.23 g of an
activated catalyst. The activated catalyst contained 4.4 wt%
- 35 -
CA 02218216 1997-10-14
palladium and 1.98 wt% tellurium. The acetoxylation reaction
of butadiene and the determination of supported-ingredient
distributions were conducted in the same manner as in Example
1, except that the catalyst prepared in this Example was
used. The results obtained are shown in Table 1.
EXAMPLE 4
27.2 g of tellurium metal was dissolved in 735.6 g of
a 35 wt% aqueous nitric acid solution. 758.8 g of 10.0 wt%
aqueous palladium nitrate solution was added thereto,
followed by sufficient 35 wt% aqueous nitric acid solution to
adjust the total volume to 1,400 ml. To the resultant
solution was added 950 g of a spherical silica support
(CARiACT-Q-15). After the support was immersed in the
solution at room temperature for 1 hour, the mixture was
filtered to remove the solution. Thereafter, the excess
solution was removed from the support with a centrifuge to
obtain an impregnated support in an amount of 2,145.5 g. The
catalyst was packed into an SUS reaction tube having an inner
diameter of 8 cm (effective sectional area, 50.2 cm2). The
catalyst was dried first at 90~C for 2 hours and subsequently
at 150~C for 2 hours while passing dry air through the tube
at a rate of 317 Nl/min, and then removed from the reaction
tube. Thus, 1,024.1 g of dried catalyst was obtained. Into
an SUS reaction tube having an inner diameter of 5.2 cm
(effective sectional area, 21.2 cm2) was packed 268.4 g of
the dried catalyst. The contents of the tube were heated to
CA 02218216 1997-10-14
150~C while passing nitrogen gas through the tube at a rate
of 5.2 Nl/min. Subsequently, while introducing hydrogen in
place of nitrogen at a rate of 5.2 Nl~min, the contents were
heated at a rate of 50~C/hr to 400~C and kept at this
temperature for 4 hours. Thereafter, the contents of the
tube were cooled in a nitrogen stream to obtain 260.5 g of an
activated catalyst. The activated catalyst contained 4.9 wt%
palladium and 1.76 wt% tellurium. The acetoxylation reaction
of butadiene and the determination of supported-ingredient
distributions were conducted in the same manner as in Example
1, except that the catalyst prepared according to this
Example was used. The results obtained are shown in Table 1.
EXAMPLE 5
Into a 50-ml measuring flask was introduced 1.244 g
of tellurium dioxide. 28 g of 35 wt% aqueous nitric acid
solution was added to dissolve the tellurium compound. To
this solution was added 22.09 g of 10.0 wt% aqueous palladium
nitrate solution, followed by sufficient 35 wt% aqueous
nitric acid solution to adjust the total volume to 50 ml. To
the resultant solution was added 20.56 g of a spherical
silica support (trademark CARiACT-15, manufactured by Fuji
Silysia Chemical, Ltd. (old name: Fuji-Davison Chemical,
Ltd.), particle diameter, 2.4-4.0 mm). After the support was
immersed in the solution at room temperature for 1 hour, the
mixture was filtered to remove the solution. Thereafter, the
excess solution was removed from the support with a
CA 02218216 1997-10-14
centrifuge to obtain an impregnated support in an amount of
45.39 g. The catalyst was packed into a pyrex glass tube
having an inner diameter of 2.S cm (effective sectional area,
4.9 cm2). The catalyst was dried first at 90~C for 2 hours
and then at 150~C for 2 hours, while passing nitrogen gas
through the tube at a rate of 6.7 Nl/min. Subsequently,
while introducing hydrogen in place of nitrogen at a rate of
0.42 Nl/min, the dried catalyst was heated at a rate of
50~C/hr to 400~C and kept at this temperature for 2 hours.
The contents of the tube were then cooled in a nitrogen
stream to obtain 21.89 g of an activated catalyst. The
activated catalyst contained 4.9 wt% palladium and 1.18 wt%
tellurium. The acetoxylation reaction of butadiene and the
determination of supported-ingredient distributions were
conducted in the same manner as in Example 1, except that the
catalyst prepared according to this Example was used. The
results obtained are shown in Table 1.
EXAMPLE 6
Into a 50-ml measuring flask was introduced 0.955 g
of tellurium metal. 20 g of 35 wt% aqueous nitric acid
solution was added to dissolve the metal. To this solution
was added 26.51 g of 10.0 wt~ aqueous palladium nitrate
solution, followed by sufficient 35 wt% aqueous nitric acid
solution to adjust the total volume to 50 ml. To the
resultant solution was added 20.78 g of a spherical silica
support (CARiACT-Q-15). After the support was immersed in
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CA 02218216 1997-10-14
the solution at room temperature for 1 hour, the mixture was
filtered to remove the solution. Thereafter, the excess
solution was removed from the support with a centrifuge to
obtain an impregnated support in an amount of 45.97 g. The
catalyst was packed into a pyrex glass tube having an inner
diameter of 2.5 cm (effective sectional area, 4.9 cm2). The
catalyst was dried first at 90~C for 3 hours and then at
150~C for 2 hours, while passing nitrogen gas through the
tube at a rate of 1.7 Nl/min. Subsequently, while
introducing hydrogen in place of nitrogen at a rate of 0.42
Nl/min, the dried catalyst was heated at a rate of 50~C/hr to
400~C and kept at this temperature for 2 hours. The contents
of the tube were then cooled in a nitrogen stream to obtain
22.26 g of an activated catalyst. The activated catalyst
contained 4.9 wt% palladium and 1.76 wt% tellurium. The
acetoxylation reaction of butadiene and the determination of
supported-ingredient distributions were conducted in the same
manner as in Example 1, except that the catalyst prepared
according to this Example was used. The results obtained are
shown in Table 1.
COMPARATIVE EXAMPLE 1
To 56 g of a spherical silica support (manufactured
by Shell Chemical Co., Ltd.; trademark, S980G; particle
diameter, 2.4-3.4 mm) were added 57 g of 10 wt% aqueous
palladium nitrate solution and 140 g of an aqueous solution
obtained by dissolving 2.6 g of tellurium dioxide in nitric
- 39 -
CA 02218216 1997-10-14
acid. This mixture was kept at 30~C for 2 hours,
subsequently allowed to cool for S hours, and then filtered
to remove the solution. Thereafter, the excess solution was
removed from the support with a centrifuge to obtain 136 g of
a catalyst. The catalyst was packed into a pyrex glass tube
having an inner diameter of 4.6 cm (effective sectional area,
16.6 cm2). The catalyst was dried first at 65~C for 6 hours
and then at 100~C for 2 hours, while passing nitrogen gas
through the tube at a rate of 2.3 Nl/min. Thereafter, the
dried catalyst was heated to 150~C. While passing hydrogen
gas through the tube at a rate of 330 Nl/hr, the dried
catalyst was further heated at a rate of 50~C/hr to 300~C and
kept at this temperature for 4 hours. The contents of the
tube were then cooled in a nitrogen stream to obtain 60 g of
an activated catalyst. The activated catalyst contained 4.86
wt% palladium and 1.76 wt~ tellurium. The acetoxylation
reaction of butadiene and the determination of supported-
ingredient distributions were conducted in the same manner as
in Example 1, except that the catalyst prepared according to
this Example was used. The results obtained are shown in
Table 1. Figs. 2 (A) to (C) show supported-ingredient
distributions and a histogram, with respect to the
tellurium/palladium atomic ratio, of palladium present in a
layer ranging from the surface of the catalyst particles to a
depth of 30%.
_ 40 -
CA 02218216 1997-10-14
COMPARATIVE EXAMPLE 2
A catalyst was prepared in the same manner as in
Comparative Example 1, except that CARiACT-15 (trademark)
having a particle diameter of 2.4-4.0 mm, manufactured by
Fuji Silysia Chemical, Ltd. (old name: Fuji-Davison Chemical,
Ltd.), was used as a catalyst support, and the amount of
tellurium dioxide was reduced to 1.3 g. The acetoxylation
reaction of butadiene and the determination of supported-
ingredient distributions were conducted in the same manner as
in Example 1, except that the catalyst prepared according to
this Example was used. The results obtained are shown in
Table 1.
COMPARATIVE EXAMPLE 3
To 40 g of a molded peat carbon (manufactured by
Norit N.V., Holland; trademark, Sorbnorit-2X; cylindrical
form having a diameter of 2 mm and a length of 6 mm) as a
catalyst support were added 60 g of water and 60 g of a 60
wt% aqueous nitric acid solution. After this mixture was
kept at 90-to 94~C for 3 hours, it was cooled and then
filtered to remove the solution. Active carbon treated with
nitric acid was thus obtained. To this active carbon were
added 20 g of 10.0 wt% aqueous palladium nitrate solution and
120 g of an aqueous solution obtained by dissolving 0.55 g of
tellurium metal in 35 wt% nitric acid. After this mixture
was kept at 30~C for 3 hours, it was allowed to cool for 5
hours and then filtered to remove the solution. The residue
- 41 -
CA 02218216 1997-10-14
was dried for 8 hours under a reduced pressure of 240 Torr at
a maximum temperature of 140~C to obtain a catalyst having
supported thereon 4.2 wt% palladium and 0.78 w% tellurium. A
30-ml portion of the catalyst was packed into a pyrex glass
tube having an inner diameter of 2.5 cm (effective sectional
area, 4.9 cm ). The contents of the tube were heated to
350~C at a rate of 50~C/hr and then kept at this temperature
for 4 hours, while passing nitrogen containing 8 vol%
methanol through the tube at a rate of 39 Nl/hr. The
contents of the tube were then allowed to cool to room
temperature in a nitrogen stream. Subsequently, the contents
of the tube were heated to 300~C and kept at this temperature
for 10 hours, while passing nitrogen containing 2 vol% oxygen
through the tube at a rate of 39 Nl/hr, before being allowed
to cool to room temperature in a nitrogen stream.
Thereafter, the contents of the tube were heated to 350~C at
a rate of 50~C/hr and kept at this temperature for 15 hours,
while passing nitrogen containing 8 vol% methanol through the
tube at a rate of 39 Nl/hr, before being allowed to cool to
room temperature in a nitrogen stream. Subsequently, the
contents of the tube were heated to 300~C and kept at this
temperature for 4 hours, while passing nitrogen cont~in;ng 2
vol% oxygen through the tube at a rate of 39 Nl/hr, before
being allowed to cool to room temperature in a nitrogen
stream. Thereafter, the contents of the tube were heated to
350~C at a rate of 50~C/hr and kept at this temperature for 4
- 42 -
CA 02218216 1997-10-14
hours, while passing hydrogen through the tube at a rate of
39 Nl/hr, before being allowed to cool to room temperature in
a nitrogen stream. Subsequently, the contents of the tube
were heated to 300~C and kept at this temperature for 15
hours, while passing nitrogen containing 2 vol% oxygen
through the tube at a rate of 39 Nl/hr, before being allowed
to cool to room temperature in a nitrogen stream.
Thereafter, the contents of the tube were heated to 350~C at
a rate of 50~C/hr and kept at this temperature for 4 hours,
while passing hydrogen through the tube at a rate of 39
Nl/hr, before being allowed to cool to room temperature in a
nitrogen stream. The catalyst thus prepared through the
activation treatment, comprising repetitions of oxidation and
reduction, contained 4.7 wt% palladium and 0.87 wt% tellurium
supported thereon. The acetoxylation reaction of butadiene
was conducted in the same manner as in Example 1, except that
the catalyst prepared according to this Example was used.
The results obtained are shown in Table 1. Since the support
used was cylindrical, supported-ingredient distributions were
determined as follows. Ten catalyst particles were
arbitrarily selected from the catalyst obtained above. With
respect to each selected particle, the section having the
largest area was ex~mined with an EPMA (JXA-8600M,
manufactured by JEOL Ltd.) along the major diameter line,
which is the axis (the major-diameter-direction center line
in the rectangular section), and along the minor diameter
- 43 -
CA 02218216 1997-10-14
line, which is a straight line meeting the major diameter
line at its center at right angles, the examination being
conducted at intervals of 20 ~m along these lines. With
respect to each examination site, ZAF correction and
supporting percentage correction were conducted. Thus,
supported-ingredient distributions for 20 major-diameter-line
radii, an average supported-ingredient distribution for the
major-diameter-line radii, supported-ingredient distributions
for 20 minor-diameter-line radii, and an average supported-
ingredient distribution for the minor-diameter-line radii,
were determined. Values of proportion A were determined from
the average supported-ingredient distribution for the major-
diameter-line radii and that for the minor-diameter-line
radii, while proportion B was determined from the supported-
ingredient distributions for the 40 radii in total (20 major
diameter radii and 20 minor diameter radii). The results
obtained are shown in Table 1.
COMPARATIVE EXAMPLE 4
Into a 50-ml measuring flask was introduced 0.887 g
of tellurium metal. 20 g of 35 wt% aqueous nitric acid
solution was added to dissolve the metal. To this solution
was added 28. 46 g of 10.0 wt% aqueous palladium nitrate
solution, followed by sufficient 3~ wt% aqueous nitric acid
solution to adjust the total volume to 50 ml. To the
resultant solution was added 20.21 g of a spherical silica
support (CARiACT-Q-15). After the support was immersed in
- 44 -
CA 02218216 1997-10-14
the solution at room temperature for 1 hour, the mixture was
filtered to remove the solution. Thereafter, the excess
solution was removed from the support with a centrifuge to
obtain an impregnated support in an amount of 44.62 g. The
catalyst was packed into a pyrex glass tube having an inner
diameter of 2.5 cm (effective sectional area, 4.9 cm2). The
catalyst was dried first at 90~C for 3 hours and then at
150~C for 2 hours, while passing nitrogen gas through the
tube at a rate of 1.7 Nl/min. The dried catalyst was placed
in a cylindrical vessel having an inner diameter of 9.5 cm.
An 80 wt% solution of hydrazine monohydrate was sprayed over
the catalyst until all the catalyst particles were immersed
in the solution, while rotating the vessel at 20 rpm.
Thereafter, rotation of the vessel was stopped, and the
vessel was allowed to stand for 18 hours. The catalyst was
then washed with water and placed in a horizontal kiln (inner
diameter, 3 cm; effective sectional area, 7.1 cm2). The
contents of the kiln were dried first at room temperature for
1 hour and-then at 150~C for 1 hour, while rotating the kiln
at 30 rpm and passing nitrogen gas therethrough at a rate of
6.7 Nl/min. Subsequently, the dried catalyst was placed in a
pyrex glass tube having an inner diameter of 2.5 cm
(effective sectional area, 4.9 cm2). The contents of the
tube were heated to 150~C over a period of 30 minutes, while
passing nitrogen gas through the tube. Thereafter, while
introducing hydrogen in place of nitrogen at a rate of 0.42
- 45 -
CA 02218216 1997-10-14
Nl/min, the contents of the tube were heated at a rate of
50~C/hr to 400~C and kept at this temperature for 2 hours.
The contents of the tube were then cooled in a nitrogen
stream to obtain 21.65 g of an activated catalyst.
The activated catalyst contained 5.1 wt% palladium
and 1.59 wt% tellurium. The acetoxylation reaction of
butadiene and the determination of supported-ingredient
distributions were conducted in the same manner as in Example
1, except that the catalyst prepared according to this
Example was used. The results obtained are shown in Table 1.
COMPARATIVE EXAMPLE S
Into a 50-ml measuring flask was introduced 0.897 g
of tellurium metal. 20 g of 35 wt% aqueous nitric acid
solution was added to dissolve the metal. To this solution
was added 26.70 g of 10.0 wt% aqueous palladium nitrate
solution, followed by sufficient 35 wt% aqueous nitric acid
solution to adjust the total volume to 50 ml. To the
resultant solution was added 20.46 g of a spherical silica
support (CARiACT-Q-15). After the support was immersed in
the solution at room temperature for 1 hour, the mixture was
filtered to remove the solution. Thereafter, the excess
solution was removed from the support with a centrifuge to
obtain an impregnated support in an amount of 44.92 g. The
catalyst was then placed in a 200-ml round bottom flask, and
dried first at 80~C for 12 hours and then at 150~C for 3
hours, while rotating the flask at 30 rpm and introducing
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CA 02218216 1997-10-14
nitrogen gas into the flask at a rate of 0.08 Nl/min.
Subsequently, the catalyst was placed in a pyrex glass tube
having an inner diameter of 2.5 cm (effective sectional area,
4.9 cm ). The contents of the tube were heated to 150~C over
a period of 30 minutes, while passing nitrogen gas through
the tube. Thereafter, while introducing hydrogen in place of
nitrogen at a rate of 0.42 Nl/min, the contents of the tube
were heated at a rate of 50~C/hr to 400~C and kept at this
temperature for 2 hours. The contents were then cooled in a
nitrogen stream to obtain 21.86 g of an activated catalyst.
The activated catalyst contained 4.8 wt% palladium and 1.61
wt% tellurium. The acetoxylation reaction of butadiene and
the determination of supported-ingredient distributions were
conducted in the same manner as in Example 1, except that the
catalyst prepared according to this Example was used. The
results obtained are shown in Table 1. Figs. 3 (A) to (C)
show supported-ingredient distributions and a histogram, with
respect to the tellurium/palladium atomic ratio, of palladium
present in a layer ranging from the surface of the catalyst
particles to a depth of 30%.
COMPARATIVE EXAMPLE 6
Into a 50-ml measuring flask was introduced 1.062 g
of tellurium metal. 20 g of 35 wt% aqueous nitric acid
solution was added to dissolve the metal. To this solution
was added 28.55 g of 10.0 wt~ aqueous palladium nitrate
solution, followed by sufficient 35 wt% aqueous nitric acid
- 47 -
CA 02218216 1997-10-14
solution to adjust the total volume to 50 ml. To the
resultant solution was added 20.28 g of a spherical silica
support (CARiACT-Q-15). After the support was immersed in
the solution at room temperature for 1 hour, the mixture was
filtered to remove the solution. Thereafter, the excess
solution was removed from the support with a centrifuge to
obtain an impregnated support in an amount of 44.40 g. The
catalyst was placed in a 200-ml round bottom flask, and dried
first at 80~C for 4 hours and then at 150~C for 3 hours,
while rotating the flask at 30 rpm and introducing nitrogen
gas into the flask at a rate of 6.7 Nl/min. Subsequently,
the catalyst was placed in a pyrex glass tube having an inner
diameter of 2.5 cm (effective sectional area, 4.9 cm2). The
contents of the tube were heated to 150~C over a period of 30
minutes, while passing nitrogen gas through the tube.
Thereafter, while introducing hydrogen in place of nitrogen
at a rate of 0.42 Nl/min, the contents of the tube were
heated at a rate of 50~C/hr to 400~C and kept at this
temperature for 2 hours. The contents of the tube were then
cooled in a nitrogen stream to obtain 21.79 g of an activated
catalyst. The activated catalyst contained 5.1 wt% palladium
and 1.82 wt% tellurium. The acetoxylation reaction of
butadiene and the determination of supported-ingredient
distributions were conducted in the same manner as in Example
1, except that the catalyst prepared according to this
Example was used. The results obtained are shown in Table 1.
- 48 -
CA 02218216 1997-10-14
COMPARATIVE EXAMPLE 7
Into a 50-ml measuring flask was introduced 1.008 g
of tellurium metal. 20 g of 35 wt% aqueous nitric acid
solution was added to dissolve the metal. To this solution
was added 27.10 g of 10.0 wt% aqueous palladium nitrate
solution, followed by sufficient 35 wt% aqueous nitric acid
solution to adjust the total volume to 50 ml. To the
resultant solution was added 25.11 g of a spherical silica
support (CARiACT-Q-15). After the support was immersed in
the solution at room temperature for 1 hour, the mixture was
filtered to remove the solution. Thereafter, the excess
solution was removed from the support with a centrifuge to
obtain an impregnated support in an amount of 54.28 g. A
28.2-g portion of the catalyst was placed in a horizontal
kiln (inner diameter, 3 cm; effective sectional area, 7.1
cm2), and dried first at 60~C for 5 hours and then at 150~C
for 2 hours, while rotating the kiln at 30 rpm and
introducing nitrogen gas into the kiln at a rate of 4.3
Nl/min. Subsequently, the catalyst was placed in a pyrex
glass tube having an inner diameter of 2.5 cm (effective
sectional area, 4.9 cm ). The contents of the tube were
heated to 150~C over a period of 30 minutes, while passing
nitrogen gas through the tube. Thereafter, while introducing
hydrogen in place of nitrogen at a rate of 0.27 Nl/min, the
contents of the tube were heated at a rate of 50~C/hr to
400~C and kept at this temperature for 2 hours. The contents
-- 49 --
CA 02218216 1997-10-14
of the tube were then cooled in a nitrogen stream to obtain
13.98 g of an activated catalyst. The activated catalyst
contained 5.0 wt% palladium and 1.86 wt% tellurium. The
acetoxylation reaction of butadiene and the determination of
supported-ingredient distributions were conducted in the same
manner as in Example 1, except that the catalyst prepared
according to this Example was used. The results obtained are
shown in Table 1.
COMPARATIVE EXAMPLE 8
Into a 50-ml measuring flask was introduced 0.988 g
of tellurium metal. 20 g of 35 wt% aqueous nitric acid
solution was added to dissolve the metal. To this solution
was added 26.52 g of 10.0 wt% aqueous palladium nitrate
solution, followed by sufficient 35 wt% aqueous nitric acid
solution to adjust the total volume to 50 ml. To the
resultant solution was added 20.47 g of a spherical silica
support (CARiACT-Q-15). After the support was immersed in
the solution at room temperature for 1 hour, the mixture was
filtered to remove the solution. Thereafter, the excess
solution was removed from the support with a centrifuge to
obtain an impregnated support in an amount of 45.27 g. The
catalyst was packed into a pyrex glass tube having an inner
diameter of 2.5 cm (effective sectional area, 4.9 cm2). The
catalyst was dried first at 90~C for 40 hours and then at
150~C for 2 hours, while passing nitrogen gas through the
tube at a rate of 0.017 Nl/min. Subsequently, while
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CA 02218216 1997-10-14
introducing hydrogen in place of nitrogen at a rate of 0.42
Nl/min, the contents of the tube were heated at a rate of
50~C/hr to 400~C and kept at this temperature for 2 hours.
The contents of the tube were then cooled in a nitrogen
stream to obtain 21.91 g of an activated catalyst. The
activated catalyst contained 4.9 wt% palladium and 1.81 wt%
tellurium. The acetoxylation reaction of butadiene and the
determination of supported-ingredient distributions were
conducted in the same manner as in Example 1, except that the
catalyst prepared according to this Example was used. The
results obtained are shown in Table 1.
EXAMPLE 7
Into a 50-ml measuring flask was introduced 1.536 g
of telluric acid (H6TeO6; manufactured by Mitsuwa Chemical
Co., Ltd.). 16 g of water was added to dissolve the
tellurium compound. To this solution was added 28.45 g of
10.0 wt% aqueous palladium nitrate solution, followed by
sufficient water to adjust the total volume to 50 ml. To the
resultant solution was added 25.58 g of a spherical silica
support (CARiACT-Q-15). After the support was immersed in
the solution at room temperature for 1 hour, the mixture was
filtered to remove the solution. Thereafter, the excess
solution was removed from the support with a centrifuge to
obtain an impregnated support in an amount of 53.64 g. The
catalyst was dried in a stream of 250~C superheated steam (2
m/sec) for 15 minutes. The dried catalyst was packed into a
-- 51 --
CA 02218216 1997-10-14
pyrex glass tube having an inner diameter of 2.5 cm
(effective sectional area, 4.9 cm ). The catalyst was heated
to 150~C over a period of 30 minutes, while passing nitrogen
gas through the tube. Subsequently, while introducing
hydrogen in place of nitrogen at a rate of 0.51 Nl/min, the
catalyst was heated at a rate of 50~C/hr to 400~C and kept at
this temperature for 2 hours. The contents of the tube were
then cooled in a nitrogen stream to obtain 27.42 g of an
activated catalyst. The activated catalyst contained 5.2 wt%
palladium and 1.56 wt% tellurium. A 6-g portion of the
activated catalyst was packed into a glass tube having an
inner diameter of 12 mm. 1,3-Butadiene, acetic acid, and
nitrogen containing 9% oxygen were introduced into the glass
tube at rates of 6.4 g/hr, 12 ml/hr, and 1.8 Nl/hr,
respectively, and the reaction was continuously conducted for
7 hours at atmospheric pressure and a temperature of 80~C. A
portion of the reaction mixture withdrawn between 5 hours and
6 hours after initiation of the reaction, and a portion of
the reaction mixture withdrawn between 6 hours and 7 hours
after initiation of the reaction, were quantitavely analyzed
by gas chromatography to determine the reaction products.
The results of these analyses were averaged to determine the
activity and selectivity, and are shown in Table 1.
Distributions of supported ingredients were determined in the
same manner as in Example 1, except that the catalyst
prepared according to this Example was used. The results
- 52 -
CA 02218216 1997-10-14
obtained are shown in Table 1. Figs. 4 (A) to (C) show
supported-ingredient distributions and a histogram, with
respect to the tellurium/palladium atomic ratio, of palladium
present in a layer ranging from the surface of the catalyst
particles to a depth of 30~.
EXAMPLE 8
A catalyst was prepared in the same manner as in
Example 7, except that drying with superheated steam was
conducted at 150~C. The diacetoxylation reaction of
butadiene and the determination of supported-ingredient
distributions were conducted in the same manner as in Example
7, except that the catalyst prepared according to this
Example was used. The results obtained are shown in Table 1.
EXAMPLE 9
5.44 g of trimethylsilyl chloride was dissolved in
100 ml of n-hexane, and 20.01 g of a spherical silica support
(CARiACT-Q-15) was added thereto. This mixture was allowed
to stand for 18 hours with occasional shaking and then
filtered to remove the solution. The residue was washed with
100 ml of n-hexane five times and then vacuum-dried at 80~C
for 3 hours. To this hydrophobized silica support was added
50 ml of an aqueous solution containing 1.535 g of telluric
acid and 28.5 g of 10.0 wt% aqueous palladium nitrate
solution. After the support was immersed in the solution at
room temperature for 1 hour, the mixture was filtered to
remove the solution. Thereafter, the excess solution was
CA 02218216 1997-10-14
removed from the support with a centrifuge to obtain an
impregnated support in an amount of 42.68 g. The catalyst
was packed into a pyrex glass tube having an inner diameter
of 2.5 cm (effective sectional area, 4.9 cm ). The catalyst
was dried first at 90~C for 2 hours and then at 150~C for 2
hours, while passing nitrogen gas through the tube at a rate
of 1.7 Nl/min. Subsequently, while introducing hydrogen in
place of nitrogen at a rate of 0.42 Nl/min, the dried
catalyst was heated at a rate of 50~C/hr to 400~C and kept at
this temperature for 2 hours. The contents of the tube were
then cooled in a nitrogen stream to obtain 21.95 g of an
activated catalyst. The activated catalyst contained 5.0 wt%
palladium and 1.51 wt~ tellurium. The acetoxylation reaction
of butadiene and the determination of supported-ingredient
distributions were conducted in the same manner as in Example
7, except that the catalyst prepared according to this
Example was used. The results obtained are shown in Table 1.
COMPARATIVE EXAMPLE 9
Into a 50-ml measuring flask was introduced 1.535 g
of telluric acid. 16 g of water was added to dissolve the
tellurium compound. To this solution was added 28.44 g of
10.0 wt% aqueous palLadium nitrate solution, followed by
sufficient water to adjust the total volume to 50 ml. To the
resultant solution was added 26.09 g of a spherical silica
support (CARiACT-Q-15). After the support was immersed in
the solution at room temperature for 1 hour, the mixture was
- 54 -
CA 02218216 1997-10-14
filtered to remove the solution. Thereafter, the excess
solution was removed from the support with a centrifuge to
obtain an impregnated support in an amount of 54.62 g. The
catalyst was placed in a vacuum dryer (DP-32, manufactured by
Yamato Scientific Co., Ltd., Japan), and dried under vacuum
(below 50 Torr) first at 60~C for 2 hours, subsequently at
80~C for 5 hours, and then at 150~C for 2 hours. The dried
catalyst was packed into a pyrex glass tube having an inner
diameter of 2.5 cm (effective sectional area, 4.9 cm2). The
catalyst was heated to 150~C over a period of 30 minutes,
while passing nitrogen gas through the tube. Subsequently,
while introducing hydrogen in place of nitrogen at a rate of
0.54 Nl/min, the catalyst was heated at a rate of 50~C/hr to
400~C and kept at this temperature for 2 hours. The contents
of the tube were then cooled in a nitrogen stream to obtain
27.96 g of an activated catalyst. The activated catalyst
contained 5.1 wt% palladium and 1.53 wt% tellurium. The
acetoxylation reaction of butadiene and the determination of
supported-ingredient distributions were conducted in the same
manner as in Example 7, except that the catalyst prepared
according to this Example was used. The results obtained are
shown in Table 1.
COMPARATIVE EXAMPLE 10
Into a 25-ml measuring flask was introduced 0.768 g
of telluric acid. 8 g of water was added to dissolve the
tellurium compound. To this solution was added 14.21 g of
- 55 -
CA 02218216 1997-10-14
10.0 wt% aqueous palladium nitrate solution, followed by
sufficient water to adjust the total volume to 25 ml. To the
resultant solution was added 12.75 g of a spherical silica
support (CARiACT-Q-15). After the support was immersed in
the solution at room temperature for 1 hour, the mixture was
filtered to remove the solution. Thereafter, the excess
solution was removed from the support with a centrifuge to
obtain an impregnated support in an amount of 26.60 g. The
catalyst was packed into a pyrex glass tube having an inner
diameter of 2.5 cm (effective sectional area, 4.9 cm2). The
catalyst was dried first at 90~C for 2 hours and then at
150~C for 2 hours, while passing dry air through the tube at
a rate of 4.3 Nl/min. Subsequently, while introducing
hydrogen in place of dry air at a rate of 0.27 Nl/min, the
dried catalyst was heated at a rate of 50~C/hr to 400~C and
kept at this temperature for 2 hours. The contents of the
tube were then cooled in a nitrogen stream to obtain 13.68 g
of an activated catalyst. The activated catalyst contained
5.0 wt% palladium and 1.52 wt% tellurium. The acetoxylation
reaction of butadiene and the determination of supported-
ingredient distributions were conducted in the same manner as
in Example 7, except that the catalyst prepared according to
this Example was used. The results obtained are shown in
Table 1.
- 56 -
CA 02218216 1997-10-14
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CA 02218216 1997-10-14
COMPARATIVE EXAMPLE 11 (Example 1 in JP-B-59-51850)
A silica support obtained by heating Silica Gel ID
(trademark), manufactured by Fuji Silysia Chemical, Ltd. (old
name: Fuji-Davison Chemical, Ltd.), at 500~C in air for 1
hour was used as a catalyst support. To 10.02 g of this
support was added a solution obtained by dissolving 0.1750 g
of palladium chloride (manufactured by NE Chemcat Corp.) and
0.0536 g of tellurium dioxide (manufactured by Mitsuwa
Chemical Co., Ltd.) in 40 ml of 6 N hydrochloric acid. After
the support was immersed in the solution at room temperature
for 24 hours, the mixture was heated on a water bath under
vacuum first at 60~C for 2 hours and then at 80~C for 3 hours
to evaporate the volatile ingredients to dryness.
Subsequently, this solid was packed into a pyrex glass tube
having an inner diameter of 2.5 cm (effective sectional area,
4.9 cm2). The contents were dried at 150~C for 3 hours while
passing nitrogen through the tube at a rate of 1.9 Nl/min,
and were then kept first at 200~C for 3 hours and then at
400~C for 2 hours while passing nitrogen saturated at room
temperature with methanol through the tube at a rate of 1.9
Nl/min. Thereafter, the contents of the tube were cooled in
a nitrogen stream to obtain 10.17 g of an activated catalyst.
The activated catalyst contained 1.03 wt% palladium and 0.42
wt% tellurium.
The acetoxylation reaction of butadiene was conducted
in the same manner as in Example 1, except that the catalyst
- 58 -
CA 02218216 1997-10-14
prepared according to this Example was used. The results
obtained are shown in Table 2. Since the support comprised
irregularly shaped particles formed by crushing, supported-
ingredient distributions were determined as follows. Ten
catalyst particles were arbitrarily selected from the
catalyst obtained above. With respect to each selected
particle, the section having the largest area was examined
with an EPMA (JXA-8600M, manufactured by JEOL Ltd.) along the
major diameter line, which was the longest straight line in
the section, and along the minor diameter line, which was the
longest straight line meeting the major diameter line at
right angles, the examination being conducted at intervals of
20 ~m along these lines. With respect to each examination
site, ZAF correction and supporting percentage correction
were conducted. Thus, supported-ingredient distributions for
20 major-diameter-line radii, an average supported-ingredient
distribution for the major-diameter-line radii, supported-
ingredient distributions for 20 minor-diameter-line radii,
and an average supported-ingredient distribution for the
minor-diameter-line radii, were determined. Values of
proportion A were determined from the average supported-
ingredient distribution for the major-diameter-line radii and
that for the minor-diameter-line radii, while proportion B
was determined from the supported-ingredient distributions
for the 40 radii in total (20 major diameter radii and 20
minor diameter radii). The results obtained are shown in
- 59 -
CA 02218216 1997-10-14
Table 2. For the purpose of comparison, the results obtained
in Example 1 are also shown in Table 2. Since the palladium
concentration of the catalyst used in Comparative Example 11
was about 1/5 of that of the catalyst used in Example 1, the
values of activity given in Table 2 have been converted to
activities per g of palladium per hour.
Table Z
Results of High-pressure Proportion
Supported
. Reaction A (%)
Ingredlent Proportion
Pd Te/Pd Activity *2 Selectlvlty Pd Te B (%)
(%)
Ex. 1 5.0 0.26 161 . 88.3 87.2 87.1 94.4
Comp. Ex. 11 1.0 0.34 117 80.1 73.4 72.1 68.0
*2 mmol/g-Pd-h
According to the process of the present invention, in
which a conjugated diene is reacted with a carboxylic acid
and molecular oxygen in the presence of a solid catalyst to
produce the corresponding unsaturated glycol carboxylic
diester, high catalytic activity can be attained in producing
the target diester by using a solid catalyst cont~; n ing
palladium and tellurium supported as active ingredients on an
inorganic porous support, and having specific distributions
as disclosed herein. Therefore, the process and the catalyst
of the present invention have great industrial value.
While the invention has been described in detail and
with reference to specific embodiments thereof, it will be
- 60 -
-
CA 02218216 1997-10-14
apparent to one skilled in the art that various changes and
modifications can be made therein without departing from the
spirit and scope thereof.
- 61 -
