U.S. patent application number 09/734024 was filed with the patent office on 2001-11-08 for preparation of c10-c30-alkenes by partial hydrogenation of alkynes over fixed-bed supported palladium catalysts.
Invention is credited to Ansmann, Andreas, Bockstiegel, Bernhard, Brocker, Franz Josef, Etzrodt, Heinz, Haake, Mathias, Kaibel, Gerd, Kammel, Ulrich, Laupichler, Lothar, Reimer, Klaus, Stroezel, Manfred.
Application Number | 20010039368 09/734024 |
Document ID | / |
Family ID | 7934424 |
Filed Date | 2001-11-08 |
United States Patent
Application |
20010039368 |
Kind Code |
A1 |
Reimer, Klaus ; et
al. |
November 8, 2001 |
Preparation of C10-C30-alkenes by partial hydrogenation of alkynes
over fixed-bed supported palladium catalysts
Abstract
Alkenes are prepared by partial hydrogenation of alkynes in the
liquid phase at from 20 to 250.degree. C. and hydrogen partial
pressures of from 0.3 to 200 bar over fixed-bed supported palladium
catalysts which are obtainable by heating the support material in
the air, cooling, applying a palladium compound and, if required,
additionally other metal ions for doping purposes, molding and
processing to give monolithic catalyst elements, by a process in
which A) alkynes of 10 to 30 carbon atoms are used as starting
compounds, B) the palladium compound and, if required, the other
metal ions are applied to the support material by impregnation of
the heated and cooled support material with a solution containing
palladium salts and, if required, other metal ions and subsequent
drying, and C) from 10 to 2000 ppm of carbon monoxide (CO) are
added to the hydrogenation gas or a corresponding amount of CO is
allowed to form in the liquid phase by slight decomposition of a
compound which is added to the reaction mixture and eliminates CO
under the reaction conditions. The process is particularly
advantageous if the partial hydrogenation is carried out in a tube
reactor by the trickle-bed or liquid phase procedure with product
recycling at cross-sectional loadings of from 20 to 500 m.sup.3
/m.sup.2 *h. The process is particularly suitable for the
preparation of 3,7,11,15-tetramethyl-1-hexadecen-3-ol (isophytol),
3,7,11-trimethyl-1-dodecen-3-ol (tetrahydronerolidol),
3,7,11-trimethyl-1,4-dodecadien-3-ol,
3,7,11-trimethyl-1,6-dodecadien-3-o- l (dihydronerolidol),
3,7-dimethyloct-1,6-dien-3-ol or 3,7-dimethyloct-1-en-3-ol from the
corresponding alkynes.
Inventors: |
Reimer, Klaus; (Mutterstadt,
DE) ; Kaibel, Gerd; (Lampertheim, DE) ;
Kammel, Ulrich; (Speyer, DE) ; Brocker, Franz
Josef; (Ludwigshafen, DE) ; Ansmann, Andreas;
(Wiesloch, DE) ; Etzrodt, Heinz; (Neustadt,
DE) ; Stroezel, Manfred; (Ilvesheim, DE) ;
Haake, Mathias; (Mannheim, DE) ; Laupichler,
Lothar; (Frankenthal, DE) ; Bockstiegel,
Bernhard; (Romerberg, DE) |
Correspondence
Address: |
Messrs. Keil & Weinkauf
1101 Connecticut Ave., N.W.
Washington
DC
20036
US
|
Family ID: |
7934424 |
Appl. No.: |
09/734024 |
Filed: |
December 12, 2000 |
Current U.S.
Class: |
568/903 ;
585/271; 585/273 |
Current CPC
Class: |
B01J 37/0217 20130101;
B01J 23/50 20130101; B01J 37/0225 20130101; C07C 29/17 20130101;
C07C 2523/44 20130101; C07C 33/025 20130101; C07C 33/02 20130101;
C07C 11/02 20130101; C07C 29/17 20130101; B01J 35/04 20130101; C07C
29/17 20130101; C07C 5/09 20130101; B01J 23/44 20130101; C07C 5/09
20130101; B01J 37/08 20130101; B01J 35/06 20130101 |
Class at
Publication: |
568/903 ;
585/271; 585/273 |
International
Class: |
C07C 027/00 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 23, 1999 |
DE |
19962907.2 |
Claims
We claim:
1. A process for the preparation of alkenes by partial
hydrogenation of alkynes in the liquid phase at from 20 to
250.degree. C. and hydrogen partial pressures of from 0.3 to 200
bar over fixed-bed supported palladium catalysts which are
obtainable by heating the support material in the air, cooling,
applying a palladium compound and, if required, additionally other
metal ions for doping purposes, molding and processing to give
monolithic catalyst elements, wherein A) alkynes of 10 to 30 carbon
atoms are used as starting compounds, B) the palladium compound
and, if required, the other metal ions are applied to the support
material by impregnation of the heated and cooled support material
with a solution containing palladium salts and, if required, other
metal ions and subsequent drying, and C) from 10 to 2000 ppm of
carbon monoxide (CO) are added to the hydrogenation gas or a
corresponding amount of CO is allowed to form in the liquid phase
by slight decomposition of a compound which is added to the
reaction mixture and eliminates CO under the reaction
conditions.
2. A process as claimed in claim 1, wherein the fixed-bed supported
palladium catalyst used is a supported catalyst which has been
prepared from metallic support material in the form of a metal
woven fabric or a metal foil.
3. A process as claimed in claim 1, wherein the compound which
eliminates CO under the reaction conditions is contained in the
alkyne in amounts of from 0 to 80% by weight.
4. A process as claimed in claim 1, wherein mixtures of two or more
different alkynes are used as the starting compound and the
individual alkenes are separated from the resulting mixture of
different alkenes by distillation in a manner known per se.
5. A process as claimed in claim 1, which is used for the
preparation of 3,7,11,15-tetramethyl-1-hexadecen-3-ol (isophytol),
3,7,11-trimethyl-1-dodecen-3-ol (tetrahydronerolidol),
3,7,11-trimethyl-1,4-dodecadien-3-ol or
3,7,11-trimethyl-1,6-dodecadien-3- -ol (dihydronerolidol) from the
corresponding alkynes.
6. A process as claimed in claim 3, which is used for the
preparation of 3,7-dimethyloct-1,6-dien-3-ol or
3,7-dimethyloct-1-en-3-ol from the corresponding alkynes.
7. A process as claimed in claim 1, wherein the partial
hydrogenation is carried out in a tube reactor by the trickle-bed
or liquid phase procedure with product recycling at cross-sectional
loadings of from 20 to 500 m.sup.3/m.sup.2.h.
8. A process as claimed in claim 7, wherein the hydrogenation gas
mixture comprising hydrogen and CO is circulated and the hydrogen
absorption, and hence the selectivity, are controlled by means of
the CO metering.
9. A process as claimed in claim 7, wherein the partial
hydrogenation is carried out by the liquid phase procedure and the
cycle gas is injected into the reactor by means of a suitable
apparatus in very fine distribution.
10. A process as claimed in claim 1, wherein the partial
hydrogenation is carried out at a hydrogen partial pressure of from
0.5 to 20 bar.
11. A process as claimed in claim 1, wherein the partial
hydrogenation is carried out continuously in one or more reactors
connected in series.
12. A process as claimed in claim 1, wherein a fixed-bed supported
catalyst is used which is obtainable by subsequently heating it for
forming after coating of the support material with palladium.
Description
[0001] The present invention relates to a very advantageous process
for the industrial production of relatively high molecular weight
alkenes, in particular of monosubstituted alkenes, by partial
hydrogenation of the corresponding alkynes in the liquid phase over
fixed-bed supported palladium catalysts with the addition of carbon
monoxide (CO) to the hydrogenation hydrogen.
[0002] The hydrogenation of alkynes to alkenes is of major
industrial importance and is therefore the subject of extensive
prior art.
[0003] Thus, GB A 871 804 describes an improved partial
hydrogenation of acetylene compounds by the suspension procedure
using a palladium catalyst (Pd catalyst) which was doped with salt
solutions of the metals Zn, Cd, Hg, Ga, In or Tl.
[0004] Furthermore, DE A 24 31 929 describes a process for the
preparation of 2-butene-1,4-diol by hydrogenation of butynediol in
aqueous solution over a catalyst which contains Pd and one of the
elements Zn or Cd and at least one of the elements Bi or Te. The
catalyst support used is pumice or alumina.
[0005] For the partial hydrogenation of the triple bond in
intermediates for vitamins and fragrances, lead-doped Pd catalysts,
i.e. Lindlar catalysts, are usually used (cf. for example U.S. Pat.
No. 2 681 938).
[0006] Frequently, these Lindlar catalysts are also deactivated by
means of sulfur compounds in order to increase the selectivity (cf.
JP A 120 657/81). U.S. Pat No. 2 809 215 describes the batchwise
hydrogenation of 3,7,11-trimethyl-6-dodecen-1-yn-3-ol over these
Lindlar catalysts.
[0007] Finally, DE A 26 19 660 discloses a process for the
preparation of butenediol, in which butynediol in an inert solvent
is hydrogenated in the presence of a catalyst which contains
metallic Pd treated with carbon monoxide. This process can
additionally be carried out in the presence of from about 200 to
2000 ppm of CO in the hydrogenation hydrogen.
[0008] Furthermore, the use of a Pd/BaSO.sub.4 catalyst for the
preparation of butenediol is disclosed from DE A 26 05 241.
[0009] An overview of the industrially used catalyst systems for
the partial hydrogenation of triple bonds to give olefinic double
bonds is known from M. Freifelder, "Practical Catalytic
Hydrogenation", Wiley Interscience, N.Y., 1971, pages 84 to
126.
[0010] All stated processes have the disadvantage that a suspended
catalyst having a high Pd content is used. After the hydrogenation
is complete, the catalyst must be separated off from the reaction
product by settling and filtration.
[0011] It has been found that, on the industrial scale, complete
removal of the catalyst powder is possible only at very great
expense. However, traces of catalyst residues in the end product
give rise to difficulties during the further processing or during
the other use of the alkenes. There has therefore been no lack of
attempts to develop a fixed-bed catalyst having high abrasion
resistance to the partial hydrogenation of the triple bond in
alkynes in the liquid phase.
[0012] EP 0 841 314 describes a process for the hydrogenation of
3,7,11,15-tetramethyl-1-hexadecyn-3-ol (dehydroisophytol), which is
carried out over amorphous metal alloys, such as
Pd.sub.81Si.sub.19, in supercritical carbon dioxide, which have
been doped with Pb in order to increase the selectivity in the
hydrogenation to isophytol. In addition, a sulfur compound, such as
1,2-bis(2-hydroxyethylthio)ethane, had to be added to the
hydrogenation mixture in this process, in order to achieve a good
yield. The expensive catalyst preparation, the removal and
recycling of the carbon dioxide and the additional use of a
sulfur-containing compound made the process appear very
expensive.
[0013] EP 0 412 415 discloses a fixed-bed catalyst for the
hydrogenation of 3,7-dimethyloct-1-yn-3-ol (hydrodehydrolinalool)
to 3,7-dimethyloct-1-en-3-ol (hydrolinalool), which catalyst
contains palladium as an active component and metals such as Sn,
Pb, Zn, Cd, Sb or Bi as an inhibitor. The monolithic fixed-bed
palladium catalysts described in this patent and doped with
inhibitor make it possible to replace the disadvantageous
suspension procedure by the technically substantially more
advantageous trickle-bed or liquid-phase procedure over the
fixed-bed catalyst. The very high abrasion resistance of these
catalyst monoliths permits a very high gas and liquid loading.
[0014] Unfortunately, it has been found that, when a process
described in this patent is carried out continuously over
bismuth-doped fixed-bed palladium catalysts over relatively long
periods, the selectivity of the hydrogenation of
hydrodehydrolinalool to hydrolinalool slowly decreases, i.e. the
reaction product contains increasing amounts of the completely
hydrogenated 3,7-dimethyloctan-3-ol, which is due to the fact that
the bismuth dopant is lost.
[0015] EP 754 664 A states that the process according to EP B1 412
415 can be improved by metering small amounts of CO into the
hydrogenation gas. The disadvantage of this process is that the
space-time yields are still not optimum and that, in the continuous
procedure on an industrial scale, the catalysts are not stable and
not sufficiently selective over a sufficiently long time.
[0016] In the processes according to EP 754 664, EP 0 841 314 and
EP 412 415, attention is not paid to the fact that, in the
hydrogenation of alkynes, high boilers which adversely affect the
overall selectivity always form as a result of oligomerization.
However, this formation of high boilers is known from the
literature (cf. G. Ertl et al. in "Handbook of Heterogeneous
Catalysis", VCH, 1997, page 2172) and is also described in EP 0 827
944.
[0017] EP 827 944 describes a process for the hydrogenation of
polyunsaturated C.sub.2-C.sub.8-hydrocarbons over the fixed-bed
catalysts disclosed in EP 412 415, the dopants being selected from
a relatively large group of metals and the catalyst preparation
being extended to include the possibility of impregnating the
support materials. However, their use is restricted to
C.sub.2-C.sub.8-hydrocarbons. However, G. Ertl et al. in "Handbook
of Heterogeneous Catalysis", VCH, 1997, pages 2202-2204, discloses
that the selectivity in the partial hydrogenation of alkynes
depends to a great extent on the alkyne to be hydrogenated, since
factors such as mass transfer and heat transfer, adsorption and
surface reactions on the catalyst greatly affect the selectivity.
It is precisely the factors of mass transfer and heat transfer that
depend on the viscosity of the reaction medium (cf. for example M.
Baerns, H. Hofmann, A. Renken in "Chemische Reaktionstechnik",
Georg Thieme Verlag Stuttgart, 2nd edition, 1992, pages 67-97),
which is generally high for molecules of relatively high molecular
weight.
[0018] It is an object of the present invention to provide a
process for the preparation of alkenes having relatively high
molecular weights, i.e. alkenes of about 10 to 30 carbon atoms,
preferably monosubstituted alkenes of 10 to 30 carbon atoms, by
partial hydrogenation of the corresponding alkynes, which does not
have the disadvantages of the suspension procedure, is technically
simple to implement and operates with catalysts which are simple to
prepare, have long-term stability, have a high overall selectivity
and produces very little overhydrogenated products and high
boilers.
[0019] We have found, surprisingly, that this object is achieved
and that monolithic fixed-bed supported palladium catalysts which
were obtained by impregnating the heated support material with a
palladium salt solution and have been described in EP 0 827 944 for
the partial hydrogenation of low molecular weight alkynes can be
used with good selectivities for C.sub.10- to C.sub.30-alkynes,
too, if amounts of CO which are in the range from 10 to 2000 ppm
are added to the hydrogenation hydrogen or the alkyne to be
hydrogenated is mixed with the compound which decomposes to a small
extent with CO elimination but otherwise does not further intervene
in the hydrogenation.
[0020] The present invention accordingly relates to a process for
the preparation of alkenes by partial hydrogenation of alkynes in
the liquid phase at from 20 to 250.degree. C. and hydrogen partial
pressures of from 0.3 to 200 bar over fixed-bed supported palladium
catalysts which are obtainable by heating the support material in
the air, cooling, applying a palladium compound and, if required,
additionally other metal ions for doping purposes, molding and
processing to give monolithic catalyst elements, wherein
[0021] A) alkynes of 10 to 30 carbon atoms are used as starting
compounds,
[0022] B) the palladium compound and, if required, the other metal
ions are applied to the support material by impregnation of the
heated and cooled support material with a solution containing
palladium salts and, if required, other metal ions and subsequent
drying, and
[0023] C) from 10 to 2000 ppm of carbon monoxide (CO) are added to
the hydrogenation gas or a corresponding amount of CO is allowed to
form in the liquid phase by slight decomposition of a compound
which is added to the reaction mixture and eliminates CO under the
reaction conditions.
[0024] The process is particularly suitable for the partial
hydrogenation of monosubstituted alkynes, such as
3,7-dimethyloct-6-en-1-yn-3-ol (dehydrolinalool) or
3,7-dimethyloct-1-yn-3-ol (hydrodehydrolinalool). The partial
hydrogenation of monosubstituted alkynes is known to be
substantially more problematic than that of disubstituted alkynes,
such as butyne-1,4-diol, since the monosubstituted alkynes can
react further during the hydrogenation. Accordingly, the partial
hydrogenation of disubstituted alkynes, such as butyne-1,4-diol, is
also possible using the novel process.
[0025] Examples of suitable starting materials for the novel
process are:
[0026] Monosubstituted alkynes, such as dehydrolinalool,
hydrodehydrolinalool, 1-ethynyl-2,6,6-trimethylcyclohexanol and
17-ethynylandrost-5-ene-3.beta.,17.beta.-diol,
3,7,11,15-tetramethyl-1-he- xadecyn-3-ol (dehydroisophytol),
3,7,11-trimethyldodec-1-yn-3-ol,
3,7,11-trimethyl-4-dodecen-1-yn-3-ol and
3,7,11-trimethyl-6-dodecen-1-yn-- 3-ol (dehydrodihydronerolidol)
and disubstituted alkynes, such as 4-methyl-4-hydroxy-2-decyne,
1,1-diethoxy-2-octyne and
bis(tetrahydro-2-pyranyloxy)-2-butyne.
[0027] The starting compounds can also be used in the form of a
mixture of two or more different alkynes. The individual alkenes
can then be separated in a manner known per se, for example by
distillation, from the resulting mixture of various alkenes.
[0028] If the starting alkynes were prepared by reacting acetylene
with a ketone, the unreacted ketone may be present as a mixture
with the alkynes in the novel process. This even has the advantage
that the ketone is capable of eliminating small amounts of CO,
which can make the metering in of CO superfluous.
[0029] Woven fabrics of inorganic materials, such as
Al.sub.2O.sub.3 and/or SiO.sub.2, or woven fabrics of wires
comprising plastics, such as polyamides, polyesters, polypropylene,
polytetrafluoroethylene, etc., may be used as catalyst support
material. However, foil-like or fabric-like metal supports, i.e.
foils or woven wire fabrics comprising metals, such as iron, spring
steel, copper, brass, aluminum, nickel silver, nickel, chromium
steel or chromium nickel steels, are particularly suitable. Foils
or woven fabrics of materials having material numbers 1.4767,
1.4401 and 1.4301 have proven particularly useful. The designation
of these materials with the stated material numbers is in line with
the material numbers stated in the Stahleisenliste, published by
the Verein Deutscher Eisennuttenleute; 8th edition, pages 87, 89
and 106, Verlag Stahleisen mbH, Dusseldorf 1990. The material
having material number 1.4767 is also known under the name Kanthal.
These metallic supports are pretreated by oxidative heating,
preferably in the air, at from 600 to 1100.degree. C., preferably
from 700 to 1000.degree. C.
[0030] The application of the palladium is carried out by simple
impregnation of the support material with Pd-containing solutions
which are prepared by dissolving salts of palladium with inorganic
or organic acids, preferably nitrates, in a solvent, preferably
water. The metal salt solution may furthermore contain one or more
promoter elements, which may originate from groups II to V and IB
to VIIIB of the Periodic Table of the Elements. Particularly
preferably used dopant metals are Cu, Ag and Au. The impregnation
is followed by a drying step in which the woven fabric is
preferably moved. This is followed by a calcination step.
[0031] The amounts of applied Pd may be from 5 to 1000, preferably
from 30 to 500, mg/m.sup.2 of fabric area. The amounts of the
additional promoters are in general from about 0.5 to 800,
preferably from 1 to 500, mg/m.sup.2 of fabric area.
[0032] The support material coated in this manner with palladium
can then be formed by heating at from 200 to 800.degree. C.,
preferably from 300 to 700.degree. C., for from 0.5 to 2 hours.
Depending on the type of palladium coating, this heating step after
the coating can however also be omitted. The catalyst foils,
catalyst nets or woven fabric coated in this manner with Pd and, if
required, subsequently heated are then expediently molded in a
manner known per se to give monoliths or moldings, e.g. Sulzer
packings, for installation in the hydrogenation reactor. This makes
it possible to establish the desired good flow conditions in the
reactor.
[0033] After the reduction of the catalyst with hydrogen at from 20
to 250.degree. C., preferably from 70 to 200.degree. C., which is
advantageously carried out in the reactor, the catalyst is ready
for use for the novel partial hydrogenation.
[0034] The novel process is advantageous if the partial
hydrogenation is carried out continuously in a tube reactor by the
trickle-bed or liquid phase procedure with product recycling with
cross-sectional loading of from 20 to 500, preferably from 100 to
300, m.sup.3/m.sup.2*h.
[0035] It is also very advantageous if, like the liquid product,
the hydrogenation gas mixture comprising hydrogen and CO is also
circulated with similar cross-sectional loadings.
[0036] The rate of hydrogen absorption is a measure of selectivity.
If too much hydrogen is reacted per unit time, a high proportion of
overhydrogenated byproduct is obtained; if too little hydrogen is
reacted per unit time, a high proportion of oligomeric,
high-boiling byproducts is obtained. Since the rate of hydrogen
absorption is dependent on the CO concentration in the
hydrogenation mixture, the novel process opens up the very
advantageous possibility of establishing the selectivity by means
of the CO metering.
[0037] The partial hydrogenation is particularly advantageous on an
industrial scale if it is carried out by the liquid phase procedure
and the cycle gas is sprayed in very fine distribution into the
reactor by means of the liquid stream and a suitable apparatus,
such as a liquid-gas compressor. In conjunction with the shaping of
the catalyst monoliths and the described gassing of the reactor,
high space-time yields are achieved by optimum cross-mixing and
good hydrodynamics of the catalyst interface. The partial
hydrogenations are carried out at from 20 to 250.degree. C.,
preferably from 60 to 200.degree. C., depending on the
substance.
[0038] The partial hydrogenation is advantageously carried out
continuously in one or more reactors connected in series. The
hydrogen partial pressure is in general from 0.3 to 200, preferably
from 0.5 to 20, bar. The hydrogenations can be carried out with or
without exit gas.
[0039] With the aid of the novel process, it is possible to prepare
many alkenes required as fragrances or intermediates for active
ingredients, such as vitamins, in particular monosubstituted
alkenes, such as linalool, hydrolinalool,
3,7,11,15-tetramethyl-1-hexadecen-3-ol (isophytol),
3,7,11-trimethyl-1-dodecen-3-ol (tetrahydronerolidol),
3,7,11-trimethyl-1,4-dodecadien-3-ol or
3,7,11-trimethyl-1,6-dodecadien-3- -ol (dihydronerolidol), from the
corresponding alkynes in good yields and good space-time yields and
with constantly good selectivities, also on an industrial scale, in
a continuous process over catalysts which can be relatively easily
prepared, contain only a small amount of Pd, are abrasion-resistant
and are stable over long periods.
[0040] The procedure for the catalyst preparation and that for the
novel partial hydrogenation are illustrated in comparison with
those according to the most closely related prior art, by means of
the following examples.
EXAMPLE 1
Comparative Example
[0041] A. Catalyst Preparation by Vapor Deposition on Woven Metal
Fabric
[0042] A smooth woven Kanthal fabric (material number 1.4767)
having a mesh size of 180 .mu.m and a wire diameter of 112 .mu.m
was heated in the air for 5 hours (h) at 950.degree. C. A 20 cm
wide fabric strip was clamped on the winding apparatus installed in
an ultra high vacuum vapor deposition unit and then coated
continuously with 2 nm of Pd at 10.sup.-6 mbar by vapor deposition.
By rewinding the fabric, the latter was coated with 0.7 nm of Bi in
a second vapor deposition step. After the vapor deposition, the
catalyst intermediate was formed for 30 minutes (min) at
600.degree. C. in an electric muffle furnace. For this purpose, the
heating furnace was heated to 600.degree. C. in the course of 40
minutes, kept at this temperature for 30 minutes and then switched
off. After cooling, the catalyst was removed from the muffle
furnace and shaped into a monolith.
[0043] B. Batchwise Selective Hydrogenation of
3,7,11,15-tetramethyl-1-hex- adecyn-3-ol (dehydroisophytol) to
3,7,11,15-tetramethyl-1-hexadecen-3-ol (isophytol) without the
Supply of CO.
[0044] The supported Pd/Bi catalyst prepared according to Example
1A, in the form of a metal monolith having a diameter of 13.2 mm
and a height of 200 mm, was introduced into a tube reactor. 300 g
of a mixture of dehydroisophytol containing about 18% by weight of
6,10,14-trimethylpentadecan-2-one (hexahydrofarnesylacetone) were
passed over the catalyst by the liquid phase procedure with
recycling with a cross-sectional loading of 200 m.sup.3/m.sup.2*h.
Hydrogen was circulated at a partial pressure of 2 bar,
simultaneously with the liquid stream. In the exit gas, whose
composition corresponded to that of the cycle gas, a CO
concentration of 20 ppm was measured after 60 minutes, which CO had
formed from a ketone since no CO was fed in. At 110.degree. C.,
complete conversion was achieved after 170 min. The overall
selectivity was 93.2%, the byproducts being distributed over
overhydrogenated product and residue in the ratio of 1:2.8.
EXAMPLE 2
[0045] A. Catalyst Preparation
[0046] The same smooth Kanthal fabric as in Example 1A was heated
for 5 h at 900.degree. C in the presence of air. A 20 cm wide
fabric strip was clamped on a winding apparatus and then
transported continuously through an impregnation bath which
contained an aqueous metal salt solution comprising palladium
nitrate and silver nitrate. The subsequently dried fabric strip had
a coating of 73 mg of Pd/m.sup.2 and 18 mg of Ag/m.sup.2. The
catalyst intermediate was formed for 3 h at 300.degree. C. in an
electric muffle furnace. The catalyst was then shaped into a
monolith as described in Example 1A.
[0047] B. Batchwise Selective Hydrogenation of Dehydroisophytol to
Isophytol without the Supply of CO.
[0048] Supported Pd/Ag catalyst prepared according to Example 2A,
in the form of a metal monolith having a diameter of 13.2 mm and a
height of 200 mm, was introduced into a tube reactor. 300 g of a
mixture of dehydroisophytol containing about 18% by weight of
hexahydrofarnesylacetone were passed over the catalyst by the
liquid phase procedure with recycling with a cross-sectional
loading of 200 m.sup.3/m.sup.2 *h. Hydrogen was circulated at a
partial pressure of 2 bar, simultaneously with the liquid stream.
In the exit gas, whose composition corresponded to that of the
cycle gas, a CO concentration of 20 ppm was measured after 60 min,
which CO must have been formed from the ketone since no CO was fed
in. At 110.degree. C., complete conversion was achieved after 125
min. The overall selectivity was 95.0% of theory, byproducts being
distributed over overhydrogenated product and residue in the ratio
1:0.54.
EXAMPLE 3
[0049] A. Catalyst Preparation
[0050] The same smooth Kanthal fabric as in Example 1A was heated
for 5 h at 900.degree. C. in the presence of air. A 20 cm wide
fabric strip was clamped on a winding apparatus and then
transported continuously through an impregnation bath which
contained an aqueous metal salt solution comprising palladium
nitrate and silver nitrate. The subsequently dried fabric strip had
a coating of 146 mg of Pd/m.sup.2 and 73 mg of Ag/m.sup.2. The
catalyst intermediate was then formed and shaped into a monolith,
these steps being carried out as described in Example 2A.
[0051] B. Batchwise Selective Hydrogenation of
3,7,11-trimethyl-6-dodecen-- 1-yn-3-ol (dehydrodihydronerolidol) to
3,7,11-trimethyl-1,6-dodecadien-3-o- l (dihydronerolidol) without
the Supply of CO.
[0052] The Pd/Ag catalyst prepared according to Example 3A, in the
form of a metal monolith having a diameter of 13.2 mm and a height
of 200 mm, was introduced into a tube reactor. 300 g of a mixture
comprising dehydrodihydronerolidol and containing about 36% by
weight of 6,10-dimethyl-5-undecan-2-one (H-geranylacetone) were
passed over the catalyst by the liquid phase procedure with
recycling with a cross-sectional loading of 200 m.sup.3/m.sup.2*h.
Hydrogen was circulated at a partial pressure of 2 bar,
simultaneously with the liquid stream. In the exit gas, whose
composition corresponded to the cycle gas, a CO concentration of 20
ppm was measured after 60 min, which CO must have been formed from
the ketone since no CO was fed in. At 110.degree. C., complete
conversion was achieved after 180 min. The overall selectivity was
93.6%, the byproducts being distributed over overhydrogenated
product and residue in the ratio 1:1.1.
EXAMPLE 4
[0053] A. Catalyst Preparation
[0054] The catalyst preparation was carried out as in Example 2A,
except that the monoliths prepared from the fabric had different
dimensions.
[0055] B. Batchwise Selective Hydrogenation of Dehydroisophytol to
Isophytol without the Supply of CO. 20 monoliths of the Pd/Ag
catalyst prepared according to Example 4A and having a diameter of
35 mm and a height of 50 mm were introduced into a tube reactor.
2200 g of a mixture comprising dehydroisophytol and containing
about 18% by weight of hexahydrofarnesylacetone were passed over
the catalyst by the liquid phase procedure with recycling with
cross-sectional loading of 200 m.sup.3/m.sup.2*h. Hydrogen was
circulated at a partial pressure of 2 bar, simultaneously with the
liquid stream. In the exit gas, whose composition corresponded to
that of the cycle gas, a CO concentration of 96 ppm was measured
after 45 min, which CO must have been formed from the ketone as no
CO was fed in. At 98.degree. C., complete conversion was achieved
after 60 min. The overall selectivity was 94% of theory, the
byproducts being distributed over overhydrogenated product and
residue in the ratio 1:0.24.
EXAMPLE 5
[0056] A. Catalyst Preparation
[0057] The catalyst preparation was carried out as described in
Example 2A, except that the monoliths prepared from the fabric had
different dimensions.
[0058] B. Continuous Selective Hydrogenation of
Dehydrodihydronerolidol to Dihydronerolidol.
[0059] Four monoliths of the Pd/Ag catalyst prepared according to
Example 4A and having a diameter of 35 mm and a height of 200 mm
and one monolith having a diameter of 35 mm and a height of 100 mm
were introduced into a tube reactor. A second tube reactor was
filled with 5 monoliths having a diameter of 27 mm and a height of
50 mm. The first reactor was operated by the liquid phase procedure
with recycling with a liquid cross-sectional loading of 200
m.sup.3/m.sup.2*h and a hydrogen cross-sectional loading of 200
m.sup.3/m.sup.2*h at a total pressure of 7 bar. CO was metered into
the hydrogen in an amount such that the exit gas, whose composition
corresponded to that of the cycle gas, had a CO concentration of
from 1200 to 1500 ppm. The temperature in the first reactor was
110.degree. C. The feed rate of a mixture comprising
dehydrodihydronerolidol and containing about 18% by weight of
6,10-dimethylundecan-2-one (H-geranylacetone) corresponded to the
removal rate from the circulation of the first reactor, which was
fed continuously to the second reactor. The second reactor was
operated by the liquid phase procedure in a straight pass at from 4
to 5 bar, from 70 to 95.degree. C. and a CO concentration in the
hydrogen of from 1000 to 1500 ppm. After a run-time of 318 h, an
overall selectivity of 95.4% was achieved in the first reactor at a
conversion of 95.4%. The remaining conversion was realized in the
second reactor (downstream reactor). The overall reactivity was
then 96.2%, the byproducts being distributed over overhydrogenated
product and residue in the ratio 1:1.0. The space-time yield was
0.62 1 per 1 of catalyst per h.
[0060] After a run-time of 732 h an overall selectivity of 97.0%
was achieved in the first reactor at a conversion of 92.8%. The
remaining conversion was realized in the downstream reactor. The
overall selectivity was then 97.4%, the byproducts being
distributed over overhydrogenated product and residue in the ratio
1:1.1. The space-time yield was 0.76 1 per 1 of catalyst per h.
This shows that the catalyst used is subject to neither
deactivation nor deterioration in the selectivity over a long
period.
EXAMPLE 6
[0061] A. Catalyst Preparation
[0062] The catalyst preparation was carried out as described in
Example 2A, except that the monoliths prepared from the fabric had
different dimensions.
[0063] B. Continuous Selective Hydrogenation of
3,7-dimethyloct-1-yn-3-ol (hydrodehydrolinalool) to
3,7-dimethyloct-1-en-3-ol (linalool).
[0064] 20 monoliths of the Pd/Ag catalyst prepared according to
Example 4A and having a diameter of 35 mm and a height of 50 mm
were introduced into a tube reactor. The second tube reactor was
filled with 10 monoliths having a diameter of 27 mm and a height of
50 mm. The first reactor was operated by the liquid phase procedure
with recycling with a liquid cross-sectional loading of 200
m.sup.3/m.sup.2*h and a hydrogen cross-sectional loading of 200
m.sup.3/m.sup.2*h at a total pressure of 7 bar. CO was metered into
the hydrogen in an amount such that the exit gas, whose composition
corresponded to that of the cycle gas, had a CO concentration of
from 1200 to 1500 ppm. The temperature in the first reactor was
104.degree. C. The amount of hydrogenation mixture fed to the
second reactor was taken from the circulation of the first reactor.
The second reactor was operated by the liquid phase procedure in a
straight pass at from 4 to 5 bar, 70.degree. C. and a CO
concentration in the hydrogen of from 200 to 500 ppm. After a
run-time of 22 hours, an overall selectivity of 95.3% was achieved
in the first reactor at a conversion of 95.4%. The remaining
conversion was realized in the downstream reactor. The overall
selectivity was then 94.8%, the byproducts being distributed over
overhydrogenated product and residue in the ratio 1:0.93. The
space-time yield was 1.01 1 per 1 of catalyst per h.
EXAMPLE 7
[0065] Comparative Example for Example 6
[0066] A. Catalyst Preparation
[0067] The catalyst preparation took place analogously to Example
1A, except that the monoliths prepared from the fabric had
different dimensions.
[0068] B. Continuous Selective Hydrogenation of
Hydrodehydrolinalool to Linalool.
[0069] 20 monoliths of the Pd/Bi catalyst prepared according to
Example 1A and having a diameter of 35 mm and a height of 50 mm
were introduced into a tube reactor. A second tube reactor was
filled with 20 monoliths having a diameter of 27 mm and a height of
50 mm. The first reactor was operated by the liquid phase procedure
with recycling with a liquid cross-sectional loading of 200
m.sup.3/m.sup.2*h and a hydrogen cross-sectional loading of 200
m.sup.3/m.sup.2*h at a total pressure of 6bar. CO was metered into
the hydrogen in an amount such that the exit gas, whose composition
corresponded to that of the cycle gas, had a CO concentration of
from 100 to 300 ppm. The temperature in the first reactor was
90.degree. C. The amount of hydrogenation mixture fed to the second
reactor was taken from the circulation of the first reactor. The
second reactor was operated by the liquid phase procedure in a
straight pass at from 4 to 5 bar, 70.degree. C. and a CO
concentration in the hydrogen of from 50 to 150 ppm. After a
run-time of 100 hours, an overall selectivity of 90.6% was achieved
in the first reactor at a conversion of 87.9%. The remaining
conversion was realized in the downstream reactor. The overall
selectivity was then 90.4%, the byproducts being distributed over
overhydrogenated product and residue in the ratio 1:1.6. The
space-time yield was 0.36 1 per 1 of catalyst per h.
EXAMPLE 8
[0070] A. Catalyst Preparation
[0071] The catalyst preparation took place analogously to Example
2A, except that the monoliths prepared from the fabric had
different dimensions.
[0072] B. Continuous Selective Hydrogenation of Dehydroisophytol to
Isophytol.
[0073] Four monoliths of the Pd/Ag catalyst prepared-according to
Example 8A and having a diameter of 35 mm and a height of 200 mm
and one monolith having a diameter of 35 mm and a height of 100 mm
were introduced into a tube reactor. A second tube reactor was
filled with 5 monoliths having a diameter of 27 mm and a height of
50 mm. The first reactor was operated by the liquid phase procedure
with recycling with a liquid cross-sectional loading of 200
m.sup.3/m.sup.2*h and a hydrogen cross-sectional loading of 200
m.sup.3/m.sup.2*h at a total pressure of 7 bar. CO was metered into
the 40 hydrogen in an amount such that the exit gas, whose
composition corresponded to that of the cycle gas, had a CO
concentration of from 800-900 ppm. The temperature in the first
reactor was 103.degree. C. The amount of a mixture of
dehydroisophytol comprising approximately 12% by weight of
6,10,14-trimethylpentadecan-2-one (hexahydrofarnesylacetone) fed
continuously to the second reactor corresponded to the amount
withdrawn from the circulation of the first reactor. The second
reactor was operated by the liquid phase procedure in a straight
pass at from 4 to 5 bar, 110.degree. C. and a CO concentration in
the hydrogen of from in the region of 100 ppm. After a run-time of
754 hours, an overall selectivity of 96.7% was achieved in the
first reactor at a conversion of 97.4%. The remaining conversion
was realized in the second reactor (downstream reactor). The
overall selectivity was then 96.7%, the byproducts being
distributed over overhydrogenated product and residue in the ratio
1:0.38. The space-time yield was 0.67 1 per 1 of catalyst per
h.
EXAMPLE 9
[0074] A. Catalyst Preparation
[0075] The same smooth Kanthal fabric as in Example 1A was heated
in the presence of air for 5 hours at 900.degree. C. A 20 cm wide
fabric strip was clamped on a winding apparatus and then
transported continuously through an impregnation bath containing an
aqueous metal salt solution of palladium nitrate and silver
nitrate. The subsequently dried fabric strip had a coating of 278
mg of Pd/m.sup.2 and 70 mg of Ag/m.sup.2. The catalyst precursor
was subsequently formed as described in Example 2A and shaped into
a monolith.
[0076] B. Batchwise Selective Hydrogenation of
3,7,11-trimethyldodec-1-yn-- 3-ol to
3,7,11-trimethyl-1-dodecen-3-ol (tetrahydronerolidol) without the
Supply of CO.
[0077] The Pd/Ag catalyst prepared according to Example 9A, in the
form of a metal monolith having a diameter of 13.2 mm and a height
of 200 mm, was introduced into a tube reactor. 300 g of a mixture
of 3,7,11-trimethyldodec-1-yn-3-ol containing about 2% by weight of
6,10-dimethylundecan-2-one (TH-geranylacetone) was passed over the
catalyst by the liquid phase procedure with recycling with a
cross-sectional loading of 200 m.sup.3/m.sup.2*h. Hydrogen was
circulated at a partial pressure of 2 bar, simultaneously with the
liquid stream. In the exit gas, whose composition corresponded to
that of the cycle gas, a CO concentration of 20 ppm was measured
after 60 minutes, which CO had formed from the ketone since no CO
was fed in. At 110.degree. C., complete conversion was achieved
after 165 min. The overall selectivity was 94.5%, the byproducts
being distributed over overhydrogenated product and residue in the
ratio of 1:0.47.
* * * * *