Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
The object of this inven~ion is to provide a
catalyst or the production o~ cyclohexanone by ~he hydrogenation
of phenol which is high in activity and selectivity. A platinum
metal catalyst having as a support a mixture o~ an alkaline-
earth carbonate and an alkaline-earth hydrogen phosphate accom-
plishes the object of the present invention.
The prior art discloses a process for the production of
cyclohexanone wherein a special quality phenol is hydrogenated
in the liquid phase and in the presence of a palladium/activated
carbon catalyst utilizing sodium as a promoter (German laid-open
Patent Speoi~ication 1,144,262). The disadvan~ages of this
process are two-fold. First, the preparation of the catalyst
containing the promoter involves a complicated ancl costly
procedure. Further, this process involves the use of a special
quality phenol which additionally adds to the cost of the
J operation.
,~,
German~Laid~open Patent Specification 1,124,487 teaches
the hydrogenation o phenol in the gaseous phase utilizing a
. . .
25 palladium/aluminum oxide catalyst. However, this process is
:! 1
:;1
l .
"
...
`1
.
;. ~' ., ' :' .'i, . ' !, ':; ."'; .' '` ' ` '
",', ~, . : ' .: . ~ . ", ~: ' : ':i. .: ' . ': ' : ` ' : .
:: ~ : . : , ': ` ' ' :: : : : . . ...
':' ' ' ,: : :, ' ':.:~:' ~:,: : ' ' ' : ' ':
~ L~)64{~
unsatis~actory due to the ~msatisfactory conversion rate
of phenol to cyclohexanone which is a direct result of
the relatively low catalyst activity. In addition, a high
proportion of undesired cyclohexanol is obtained as a by-
product
According to another known process (Swiss Patent
Specification 463,493) phenol is hydrogenated in the trickling
phase in the presence of a palladium/aluminum catalyst.
In addition, German laid-open Patent Specification
.~ .
1,298,098) discloses the hydrogenation of phenol in the gaseous
phase in the presence of a palladium catalyst. The cata~yst
support consists of aluminum oxide and an alkaline-earth
; hydroxide.
Finally, aluminum spindels are used as a support for
a palladium catalyst in the process for hydrogenating phenol
;a8 disclosed in German laid-open Pending Patent application
2,0~5,8~2).
The previously mentioned processes ~uffer from the
same disadvantage; namely~ a relatively low activity of the
20;~ catalyst. In fact, the activity of the catalyst is directly ~`
` related to the amount of catalyQt andthe size of the apparatus j~
emplo~ed. Thereore, a low activity catalyst impalrs the
~i.
1; ,: ~ `: . : .
; economic desirability of the process.
It is with knowledge of these disadvantages ~hat the
~ present inve~tor sought a catalyst having a high ac~ivi~y
and ~electivity for the production of cyclohexanorle by the
~ hydrogenation of p~enol.
J~
; ,
~ 2
.. . . .
~ (3640()~
Surprisingly, i~ was discovered that cyclohexanone
is produced with high selec~ivity in the presence of a
greatly active platinum metal catalyst having as a support
a mixture of alkaline-earth carbonate and alkaline-earth
hydrogen phosphate.
Particularly suitable as ~he platinum metal is
palladium. The process may be performed either in the
- liquid phase or in the gaseous or trickling phase which is
preferred.
~0 While in the liquid phase the catalyst is employed
in the form of a powder. However, in the gaseous phase, the
catalyst must first be molded. For example, the catalyst
. . .
~ can be pressed into tablets, briquettes or pelle~s. This is
. ~ : .. .
made possible by the presence of the alkalin~-earth hydrogen
~;15 phosphate. If desired, the ability of the catalyst to be
molded can be enha~ced by the addition of such known aids
m as graphite or polyvinyl alcohol.
In the gaseous phase the molar ratio of hydrogen
to phenol is 3:1 to 50:1 and particularly preferred is a
.
~20 ~ molar ratio of 5:1 to 30:1. In this process it is possible
to employ a mixture of hydrogen with an i~ert gas. Nitrogen
~ is an example o~ such an inert gas. Further, prior to com-
3~ meneing hydrogena~ion in the gaseous phase, it is preferable
~.!
to activate the catalyst with hydrogen. Finally, the ca~alys~
~25 ~; ~ can be loaded at a rate of 1-3 kg phenol per liter of catalyst
per hour.
. ~
`: :
.. ` .
`~ - 3
- ~-
~06~0C~7
Generally it i9 preferrecl that the reaction
temperature be between about 110C to 250C. The
particularly preEerred temperature range ls 120C. to 220C.
The pressure of the reaction is not cr-itical and the
desired objects of the invention can be achieved by
emplo~ing standard pressure or pressures higher or lower
than standard pressure.
The catalyst preferably con~ains 0.1-10% of
platinum metal based on the total weight of the catalyst.
The particularly preferred platinum metal content is 1-5%.
All carbonates of the alkaline-earth metals may
- be employed as the carbonate constituent of the catalyst
support. Particularly desirable results are obtained with
calcium carbonate. Particularly preferred is a calcium
lS carbonate w~ich is obtained by the precipitation of water- -
: soluble calcium salt~ with water soluble carbonates. The
~: `
preferred calcium carbonate is preferably prepared by
: mixing. 5-2~/Oaqueous solutions of calcium chloride and
sodium carbonate at 50-90C and separating the precipatated
.~, .
20 ~ calcium carbonate from the solution. It is also possible
to use commercially available calcium carbonates as the
a~kaline-earth carbonate constituent of the catalyst support.
The alkaline-earth hydrogen phosphate, in particular
calcium hydrogen phosphate, is preerably added to ~he alkaline-
~25~ eart~ carbonate before addi~;ion of ~he palladium. The amount
of~cal~iu~ hydrogen~ phosphate is preferably 10-30% by weight
o ~the total weight o~ the catalyst support.
.
. . . :
::: ~
r ~ ~
~ ~ '
t ~ ~ ;r - ~1
" . .. . .. . . . .. . ..
. ~: ' - . - : ' : . .. ''' .'. : : , , ' . ' . .. .
~ 6 ~0 ~
The preparation o~ the pallaclium ca~alyst accordLng
to the present invention is advantageously effected by ~irst
mi~ing calcium carbonate with the desired amount of calcium
hydrogen phosphate and then forming a suspension with a
palladium chloride solution. The thus formed suspension
is reduced with an alkaline formaldehyde solution or hydrogen,
preferably at 40C,
After separation from the aqueous phase, the catalyst
is washed and dryed and ~hen can be employed directly for the
hydrogenation of phenol in the liquid phase to produce
cyclohexanone, If the gaseous phase is desired the catalyst
~ must first be molded as described previously.
; The following examples are recited for descriptive
purposes only and are not meant in anyway to limit the scope
,.~
~ of the present invention.
. .
.
1~ Exam~le 1
, ~ :
~ a) 3,600 parts by volume of a 20% calcium chloride
, . .
solution are added at 90C while st;rring to 6,890 parts by
volume of a 10% sodium carbonate solution. After cooling, the
calcium carbonate formed is filtered off and washed with water ~,
'~20~ until chloride ions can not be detected. Finally, the
; calcium carbonate is dried at 130C in a vacuum drying chamber.
b)~ 400 par~s by weighe o~ the thus obtained calcium
c arbonate are mixed with 100 g of calcium hydrogen phosphate
~ and stirred together a~ 40C with 29250 parts by volume of
1~2~ a solution containing 2% of palladium in the form of palladium
; chloride to form a suspension. After a short time, prac~icall~
all the palladium chloride has been absorbed on the supportO
;
~L~64~;)7
A mixture of 370 parts by volume of 4% sodium hydroxide
solution and 180 parts by volume of 40% formaldehyde
solution i5 then added slowly while stirring continously.
The reduced catalyst is filtered off, washed with water
until chloride ions cannot be detected and then dried at
130C in vacuo.
:
The catalyst contains 5~ of palladium. After
admixing 2% of graphite and 0.5% of polyvinyl alcohol with
the powder, it is pressed into tablets with a diameter of
`- 10 5 mm and a thickness of 3 - 5 mm.
c) 274 g of these catalyst tablets are put into a
heatable reaction tube. Prior to the hydrogenation, the
catalyst is treated with hydrogen for 1 hour at 120C. 720
g of vaporized phenol, together with 2,400 liters per hour
of hydrogen are then passed over the catalyst at a heating or
cooling temperature of 120 C and at a pressure of 0.1 atmos-
`1 pheres.
;,.,
The amount of phenol corresponds to a catalyst load
of 26 g phenol/g catalyst/hour. The hydrogenation product
~ 20 contains only 3.6% o phenol. In addition to 92.3% of
:,
~ cyclohexanone, there is produced 4.1~ of cyclohexanol.
,J ~ Example 2
~:
' With the hydrogenation apparatus and the catalyst
: according to Example 1,696 g of vaporized phenol, together
;~ 25 with 3,700 liters per hour of hydrogen, are passed over the
-~ catalyst at a heating temperature of 120C. This corresponds
~ to a load of 2.5 g phenol/g catalyst/hours.
, ~ :
.. -~, .
. .: ..
~ 6 -
., :
~,~.-,
4~
In addition to 6.2% o unconverted phenol, the
hydrogenation produc~ contains 90.7% of cyclohexanone and
3.1% of cyclohexanol~
Example 3
5' C 400 g of precipitated "Fluka" calcium carbonate and
100 g of calcium hydrogen phosphate are mixed and catalyst
tablets are produced therefrom as detailed in Example lb.
240 g of this catalyst are placed in a reaction
tube in accordance with Example lc. The tube is heated to
140 C and the ca~alyst is treated with hydrogen for 1 hour.
Thereafter, 750 g of vaporized phenol, together with 1,200
liters per hour of hydrogen, are passed over the catalyst at
a heating temperature of 120C. This corresonds to a
catalyst load of 3.1 g phenol/g catalyst/hour.
The hydrogenation product is composed of 92.5~ of
cyclohexanone, 3.1% of cyclohexanol, 1.2% of other by-products
and 3.2% of unconverted pheno~.
Example 4
The hydrogenation appaxatus and catalyst according to
Example 1 are used.
398 g of phenol per hour are trickled over the
catalyst at a heating temperature of 120C. At the same time,
500 1iters per hour of hydrogen are passed over the catalyst.
The catalyst load is 1.45 g phenol/g catalyst/hour.
2.4% of unconverted phenol is found in the reaction
product. Moreover, 91.4% of cyclohexanone and 6.2~ of by-
products, chiefly cyclohexanol, are contained therein.
: "
7 -
; ...... ::. . .... . . . . . .. .-. .. . . . , . . .,. .. : ,.,.. -. ,.. . - .. , . . .. -
~64~
Example 5
The catalyst is prepared in accordance with
Example la and lb, except that only 1125 parts by volume
of palladium chloride solution are employed.
The finished catalyst contains 2.5~ of palladium.
285 g of the catalyst tablets obtained are put into
a heatable reaction tube. Prior to the hydrogenation, the
catalyst is treated with hydrogen for 3 hours at 120C, 300 g
of vaporized phenol, together with 500 liters per hour of
hydrogen, are then passed over the catalyst at a heating
temperature of 130C and at a pressure of 0.2 atmospheres.
The amount of phenol corresponds to a catalyst load
of 1.05 g catalyst/hour. The hydrogenation product contains,
in addition to 1.4~ of unconverted phenol, 97.2% of cyclohexanone
and 1.4% of cyclohexanol.
- 8 -
,'~
