Carrier-supported catalyst and process for making mono-carboxylic anhydrides

Monocarboxylic anhydrides of the general formula (RCO).sub.2 O are made by reacting a carboxylic acid ester or dialkylether of the general formulae RCOOR and ROR, respectively, in which R stands for one and the same alkyl radical having from 1-4 carbon atoms, with carbon monoxide in gas phase, in the presence of iodine or bromine or their compounds as a reaction promoter and also in the presence of a carrier-supported catalyst containing noble metal compounds of group VIII of the Periodic System, at temperatures of 130.degree.-400.degree. C. and under pressures of 1-150 bars. To this end, a novel carrier-supported catalyst is used in which the carrier material has a noble metal/chelate-compound formed of the noble metal compound and a chelator containing organonitrogen, organophosphorus, organoarsenic or organosulfur groups applied to it.

This invention relates to a process for making monocarboxylic anhydrides of 
the general formula (RCO).sub.2 O by reacting a carboxylic acid ester or 
dialkylether of the following general formulae RCOOR and ROR, 
respectively, in which R stands for one and the same alkyl group having 
from 1-4 carbon atoms, with carbon monoxide in gas phase, in the presence 
of iodine or bromine or their compounds as a reaction promoter and also in 
the presence of a carrier-supported catalyst containing a noble metal 
compound selected from group VIII of the Periodic System of the elements, 
at temperatures of 130.degree.-400.degree. C. and under pressures of 1-150 
bars. 
Processes of this kind which are carried out in gas phase with the use of a 
carrier-supported catalyst have already been described in German 
Specification DE-A No. 24 50 965 and in Japanese Specification No. 
47921/1975. These processes avoid the difficulties normally accompanying 
operations in liquid phase, e.g. the difficult separation and recycle of 
suspended and partially dissolved catalyst and, under circumstances, 
promoter. 
The two Specifications describe gas phase processes wherein solid 
carrier-supported catalysts made by impregnating the carrier material with 
a dissolved or suspended and even with complex noble metal compounds are 
used. In this way, it is not possible to fix e.g. an organonitrogen or 
organophosphorus compound containing trivalent nitrogen or phosphorus in 
the carrier-supported catalyst; this however has been found generally to 
affect the catalyst performance and reaction selectivity. 
The present invention avoids this deficiency and to this end provides for 
the catalyst carrier to be impregnated with a noble metal/chelate-compound 
which has one or more promoters selected from principal group V, e.g. an 
organylamine or phosphine, already integrated in it. 
The invention comprises more particularly using 
(1) a carrier-supported catalyst in which the carrier has a noble 
metal/chelate-compound formed of the noble metal compound and a chelator 
containing organonitrogen, organophosphorus, organoarsenic or organosulfur 
groups applied to it. 
Further preferred and optional features of the invention provide: 
(2) for the carrier of the carrier-supported catalyst to have a non noble 
metal/chelate-compound formed of a non noble metal compound selected from 
the 6th or 8th subgroup of the Periodic System of the elements and a 
chelator containing organonitrogen, organophosphorus, organoarsenic or 
organosulfur groups additionally applied to it; 
(3) for the carrier-supported catalyst to contain a non noble metal 
compound selected from the 1st through 3rd principal groups or the 4th 
through 6th or 8th subgroups of the Periodic System of the elements as an 
additional promoter; 
(4) for the carrier in the carrier-supported catalyst to have a chelate 
compound and one of the following chelators: 
(a) Y--(CH.sub.2).sub.n --Y 
(b) Y--CH.dbd.CH--Y 
(c) .phi..sub.2 P--CH.dbd.CH--P.phi..sub.2 
(d) .phi..sub.2 As--CH.dbd.CH--As.phi..sub.2 
(e) .phi..sub.2 P--CH.sub.2 --CH.sub.2 --P.phi.--CH.sub.2 --CH.sub.2 
--P.phi.--CH.sub.2 --CH.sub.2 --P.phi..sub.2 
(f) .phi..sub.2 P--CH.sub.2 --CH.sub.2 --P.phi.--CH.sub.2 --CH.sub.2 
--P.phi..sub.2 
##STR1## 
(h) P(--CH.sub.2 CH.sub.2 --P.phi..sub.2).sub.3 (i) R.sup.1 
--C[--(CH.sub.2).sub.n --Y].sub.3 
##STR2## 
in which .phi. stands for C.sub.6 H.sub.5 --; 
Y stands for --Nr.sub.2.sup.2, an aryl group containing nitrogen, 
--PR.sub.2.sup.2, --AsR.sub.2.sup.2, --SR.sup.2 or --SH; 
R.sup.1 stands for --H, a C.sub.1 -C.sub.5 -alkyl or --C.sub.6 H.sub.5 ; 
R.sup.2 stands for a C.sub.1 -C.sub.6 -alkyl, a C.sub.5 -C.sub.8 
-cycloalkyl or --C.sub.6 H.sub.5 or C.sub.6 H.sub.5 CH.sub.2 --; 
n stands for 1 through 6, preferably 1-4; 
m stands for 0 through 8, preferably 0-3, and 
x stands for 1 or 2 applied to it; 
(5) for the carrier-supported catalyst to contain an inorganic oxidic 
carrier or an active carbon carrier. 
(6) for the carrier-supported catalyst to contain altogether 0.01-50 wgt %, 
preferably 0.1-20 wgt %, chelate compound and non noble metal compound, if 
desired; 
(7) for the carrier-supported catalyst to be used in the form of particles 
having a size of 1 through 20 mm. 
The invention also relates to the catalyst itself which is used for making 
monocarboxylic anhydrides by subjecting a suitable ester or ether to a 
carbonylation reaction and which is characterized in that the carrier has 
a noble metal/chelate-compound formed of a noble metal belonging to the 
8th subgroup of the Periodic System of the elements and a chelator 
containing organonitrogen, organophosphorus, organoarsenic or organosulfur 
groups applied to it. 
Further preferred and optional features of the carrier-supported catalyst 
of this invention provide: 
(1) for the carrier to have a non noble metal/chelate-compound formed of a 
non noble metal selected from the 6th or 8th subgroup of the Periodic 
System of the elements and a chelator containing organonitrogen, 
organophosphorus, organoarsenic or organosulfur groups additionally 
applied to it; 
(2) for the carrier-supported catalyst to contain a non noble metal 
compound selected from the 1st through 3rd principal groups or the 4th 
through 6th or 8th subgroups of the Periodic System of the elements as an 
additional promoter; 
(3) for the carrier to have a chelate compound formed of a metal compound 
and one of the chelators identified under item (4), (a) through (k) 
hereinabove applied to it; 
(4) for the carrier-supported catalyst to contain an inorganic oxidic 
carrier or active carbon; 
(5) for the carrier-supported catalyst to contain altogether 0.01-50 wgt %, 
preferably 0.1-20 wgt %, chelate compound and non noble metal compound, if 
desired. 
The catalyst carriers which should preferably be used comprises inorganic 
oxides, e.g. SiO.sub.2, Al.sub.2 O.sub.3, MgO, TiO.sub.2, La.sub.2 
O.sub.3, ZrO.sub.2, zeolite, clay, NiO, Cr.sub.2 O.sub.3, WO.sub.3 or 
corresponding mixed oxides, but also active carbon having a BET-surface 
area of 1-1000 m.sup.2 /g, preferably 30-400 m.sup.2 /g. 
The promoters of the 5th or 6th principal group are chemically combined in 
the chelators used and constitute themselves one of their functional 
groups encasing the noble metal compounds selected from group VIII, 
especially Rh, Ir, Pd, or Ru, and also the non noble metal compounds, if 
any, selected from the 6th or 8th subgroup, especially Cr or Ni, but also 
W, Fe and Co, like pincers of a cray-fish. 
One of the advantages of the carrier-supported catalyst and process of this 
invention resides in the fact that the promoters necessary for increasing 
the catalyst performance and selectivity and selected from principal group 
V or VI of the Periodic System of the elements form a functional group Y 
in the chelators and thus are fixed. It is therefore unnecessary, e.g. for 
an organonitrogen or organophosphorus promoter to be separated and 
recycled. The present process for making monocarboxylic anhydrides 
compares favorably in its higher catalyst performance and selectivity with 
the prior art methods described hereinabove, which are also carried out in 
gas phase and with the use of a carrier-supported catalyst. 
A further advantage of ths invention is seen to reside in the fact that the 
noble metal/chelate-compounds and optionally non noble 
metal/chelate-compounds applied to the carrier fail to commence melting at 
the reaction temperatures necessary for making monocarboxylic anhydrides. 
The carrier-supported catalyst and process of this invention are more 
particularly used for making acetic anhydride from methyl acetate or 
dimethylether in the presence of methyl iodide or methyl bromide as a 
reaction promoter. Further suitable promoters are HI, HBr or more 
generally RI or RBr, where R stands for an alkyl group having 1-4 carbon 
atoms. 
The useful carrier materials have already been specified hereinabove; 
useful mixed oxides are, e.g. Cr.sub.2 O.sub.3 --Al.sub.2 O.sub.3, 
WO.sub.3 --Al.sub.2 O.sub.3, MgO--Al.sub.2 O.sub.3, SiO.sub.2 --Al.sub.2 
O.sub.3 or ZrO.sub.2 --Al.sub.2 O.sub.3. The carrier-supported catalyst 
should preferably contain 0.01-5 wgt % noble metal and present a particle 
size of 1 to 20 mm. 
The noble metal compounds which should conveniently be used for making the 
present carrier-supported catalyst, comprise e.g. the following compounds 
Rhodium: 
RhCl.sub.3, RhCl.sub.3.3H.sub.2 O, RhBr.sub.3, RhI.sub.3, 
Rh(NO.sub.3).sub.3, Rh.sub.2 (CO).sub.4 Cl.sub.2, Rh.sub.2 (CO).sub.4 
Br.sub.2, Rh(CO).sub.4 I.sub.2, [P(C.sub.6 H.sub.5).sub.3 ].sub.3 RhCl, 
[P(C.sub.6 H.sub.5).sub.3 ].sub.2 Rh(CO)Cl, Rh.sub.6 (CO).sub.16, Rh.sub.4 
(CO).sub.12, Rh.sub.2 (O.sub.2 CCH.sub.3).sub.4, [RhCl(C.sub.8 
H.sub.12)].sub.2 ; 
Iridium: 
IrCl.sub.3, [Ir(CO).sub.3 Cl].sub.2, Ir[P(C.sub.6 H.sub.5).sub.3 ].sub.2 
(CO)Cl, Ir.sub.4 (CO).sub.12, [IrCl(C.sub.8 H.sub.12)].sub.2, Cl(CO).sub.2 
Irpyr (pyr=C.sub.6 H.sub.5 N); 
Palladium: 
PdCl.sub.2, PdBr.sub.2, PdI.sub.2, (CH.sub.3 CO.sub.2).sub.2 Pd[P(C.sub.6 
H.sub.5).sub.3 ].sub.2, PdCl.sub.2 [P(C.sub.6 H.sub.5).sub.3 ].sub.2, 
Pd(O.sub.2 CCH.sub.3).sub.2, PdCl.sub.2 (C.sub.8 H.sub.12), (C.sub.6 
H.sub.5 CN).sub.2 PdCl.sub.2 ; 
Ruthenium: 
RuCl.sub.3, Ru.sub.3 (CO).sub.12, RuCl.sub.2 [P(C.sub.6 H.sub.5).sub.3 
].sub.3, RuCl.sub.2 (CO).sub.2 [P(C.sub.6 H.sub.5).sub.3 ].sub.2, 
[RuCl.sub.2 (CO).sub.3 ].sub.2. 
Useful non noble metal compounds selected from the 6th or 8th subgroup, 
especially Cr, Ni, but also W, Fe, Co which also undergo reaction with the 
chelator, comprise e.g. the following: 
Chromium: 
Cr(CO).sub.6, CrCl.sub.3, C.sub.7 H.sub.8 Cr(CO).sub.3. 
Nickel: 
Ni(CO).sub.4, [P(C.sub.6 H.sub.5).sub.3 ].sub.2 Ni(CO).sub.2, NiCl.sub.2, 
Ni(C.sub.8 H.sub.12).sub.2. 
The non noble metal compounds selected from the 1st through 3rd principal 
groups or the 4th through 6th subgroups or 8th subgroup of the Periodic 
System of the elements, preferably compounds of Li, Na, Mg, Ca, Al, Ti, 
Zr, V, Cr, W, Fe, Co, Ni are comprised, e.g. of hydroxides, carbonates, 
carbonyls, hydrides, halides and further salts. It is possible for these 
non noble metal compounds to be additionally applied to the catalyst 
carrier, e.g. in the form of a solution by impregnating the carrier 
therewith. 
For making the carrier-supported catalyst of this invention, it is 
necessary first to have the chelator with the functional groups Y, which 
is a commercially available product or can be made by methods described in 
literature. Speaking generally, the chelator is contacted with a solution 
of one of the noble metal compounds of group VIII and, if desired, one of 
the non noble metal compounds of the 6th or 8th subgroups with the 
resultant formation, in known fashion, of chelate compounds having melting 
points higher than the temperature commonly employed in a carbonylation 
reaction for making monocarboxylic anhydrides. Next, the carrier material 
is impregnated with the dissolved conventional chelate compounds to give 
the finished catalyst. The solvents for the chelate compounds comprise 
polar and unpolar solvents, e.g. dichloromethane (methylene chloride), 
chloroform, methanol, benzene, toluene or xylene, in which the carrier 
material is suspended. Details are indicated in the catalyst description 
hereinafter. 
The quantitative ratio of carboxylic acid ester or dialkylether and 
iodine(compound) or bromine(compound) in the reaction zone may vary within 
wide limits. Generally, however, 1 to 500 mols, preferably 1 to 100 mols, 
carboxylic acid ester and/or dialkylether is used per 1 mol iodine 
(compound) or bromine(compound). The temperature selected for the reaction 
zone should be high enough to always have a gaseous reaction mixture 
therein, irrespective of the conversion rate, and preferably is between 
150.degree. and 250.degree. C. The preferred pressure is between 5 and 30 
bars. 
The reaction mixture should conveniently be contacted with the solid 
carrier-supported catalyst over a period of from 1 to 1000 seconds, 
preferably 1 to 180 seconds. The conversion should suitably be effected in 
a flow tube arranged in upright position, packed with the 
carrier-supported catalyst or in an autoclave provided with a stirrer or 
in a shaking autoclave, having the carrier-supported catalyst placed 
therein. While the carbonylation is generally effected under practically 
anhydrous conditions, it is allowable for it to be carried out in the 
presence of minor amounts of water as they are normally found in 
commercially available starting materials, which however should not exceed 
1 mol %, based on the starting materials. In addition, the carbonylation 
remains substantially uneffected by the presence of minor amounts of 
methanol in the starting materials or of hydrogen in commercial carbon 
monoxide. 
The reaction mixture coming from the carbonylation zone is gaseous and 
contains carbon monoxide, methyl iodide, acetic anhydride, unreacted 
methyl acetate or dimethylether and, under circumstances, minor 
proportions of acetic acid. The gaseous reaction mixture is cooled with 
condensation of acetic anhydride, under circumstances, acetic acid. 
Uncondensed gases, such as CO, CH.sub.3 I, methyl acetate or dimethylether 
are recycled to the reaction zone, the reacted ester or ether and CO 
portions being continuously renewed. The anhydrides are easy to separate, 
i.e. in uncomplicated fashion, by cooling the effluent reaction mixture 
and recycling the uncondensed gas. This is a particular advantage of the 
process of this invention. The carrier-supported catalyst is not 
contaminated; it remains in the reaction zone. As a result, the entire 
process is rendered considerably simpler.

The following Examples illustrate the invention which is naturally not 
limited thereto: 
EXAMPLES 
Autoclave test 
A stainless steel (Hastelloy C) autoclave (capacity 0.25 l) provided with a 
stirrer, various inlets and outlets and a turnable basket receiving the 
catalyst was used. The carboxylic acid ester or dialkylether was reacted 
in gas phase with CO-gas in the presence of the agitated solid 
carrier-supported catalyst. The catalyst was placed in the turnable 
catalyst basket which also permitted the gases to be mixed. The autoclave 
was charged with 2.5 ml of a liquid mixture of 20 volume parts methyl 
iodide and 80 volume parts ester or ether, and heated to the reaction 
temperature. The carbonylation was started by injecting carbon monoxide. 
The CO-pressure was maintained constant by continued injection of gas. 
Details are indicated in the Examples. 
EXAMPLE 1 
2 ml (1.86 g) methyl acetate, 0.5 ml (1.14 g)methyl iodide and 1.60 g 
catalyst No. 1 were reacted in the autoclave with carbon monoxide at 
180.degree. C. under a CO-pressure of 20 bars. After a reaction period of 
1 h, the catalyst performance was found to be 260 g Ac.sub.2 O per g Rh 
per hour. The yield of Ac.sub.2 O, based on the ester used, was 64% and 
the selectivity 95%. 
EXAMPLE 2 
2 ml (1.86 g) methyl acetate, 0.5 ml (1.14 g) methyl iodide and 1.60 g 
catalyst No. 1 were reacted in the autoclave with carbon monoxide at 
175.degree. C. under a CO-pressure of 20 bars. After a reaction period of 
1 h, the catalyst performance was found to be 220 g Ac.sub.2 O per g Rh 
per hour. The yield of Ac.sub.2 O, based on the ester used, was 54% and 
the selectivity 96%. 
EXAMPLE 3 
2 ml (1.86 g) methyl acetate, 0.5 ml (1.14 g) methyl iodide and 1.77 g 
catalyst No. 2 were reacted in the autoclave with carbon monoxide at 
166.degree. C. under a CO-pressure of 20 bars. After a reaction period of 
1 hour, the catalyst performance was found to be 280 g Ac.sub.2 O per g Rh 
per hour. The yield of Ac.sub.2 O, based on the ester used, was 64% and 
the selectivity 97%. 
EXAMPLE 4 
2 ml (1.86 g) methyl acetate, 0.5 ml (1.14 g) methyl iodide and 1.77 g 
catalyst No. 2 were reacted in the autoclave with carbon monoxide at 
180.degree. C. under a CO-pressure of 20 bars. After a reaction period of 
1 hour, the catalyst performance was found to be 380 g Ac.sub.2 O per g Rh 
per hour. The yield of Ac.sub.2 O, based on the ester used, was 86% and 
the selectivity 93%. 
EXAMPLE 5 
2 ml (1.86 g) methyl acetate, 0.5 ml (1.14 g) methyl iodide and 1.78 g 
catalyst No. 3 were reacted in the autoclave with carbon monoxide at 
200.degree. C. under a CO-pressure of 20 bars. After a reaction period of 
1 hour, the catalyst performance was found to be 35 g Ac.sub.2 O per g Rh 
per hour. The yield of Ac.sub.2 O, based on the ester used, was 11.6% and 
the selectivity 87%. 
EXAMPLE 6 
2 ml (1.86 g) methyl acetate, 0.5 ml (1.14 g) methyl iodide and 1.70 g 
catalyst No. 4 were reacted in the autoclave with carbon monoxide at 
180.degree. C. under a CO-pressure of 20 bars. After a reaction period of 
1 hour, the catalyst performance was found to be 450 g Ac.sub.2 O per g Rh 
per hour. The yield of Ac.sub.2 O, based on the ester used, was 24% and 
the selectivity 94.7%. 
EXAMPLE 7 
2 ml (1.86 g) methyl acetate, 0.5 ml (1.14 g) methyl iodide and 4.4 g 
catalyst No. 5 were reacted in the autoclave with carbon monoxide at 
180.degree. C. under a CO-pressure of 20 bars. After a reaction period of 
1 hour, the catalyst performance was 150 g Ac.sub.2 O per g Rh per hour. 
The yield of Ac.sub.2 O, based on the ester used, was 78% and the 
selectivity 94%. 
EXAMPLE 8 
2 ml (1.86 g) methyl acetate, 0.5 ml (1.14 g) methyl iodide and 1.7 g 
catalyst No. 6 were reacted in the autoclave with carbon monoxide at 
180.degree. C. under a CO-pressure of 20 bars. After a reaction period of 
1 hour, the catalyst performance was found to be 190 g Ac.sub.2 O per g Rh 
per hour. The yield of Ac.sub.2 O, based on the ester used, was 45% and 
the selectivity 93%. 
EXAMPLE 9 
A steel tube 20 mm wide and 450 mm long was used as a flow tube in upright 
position and charged with 27.4 g catalyst No. 2 which however contained 
0.4 wgt % Rh. 11 Nl CO (Nl=liter measured at 0.degree. C. under 1.013 bar) 
and an evaporated mixture (13 ml liquid) of methyl acetate and methyl 
iodide (molar ratio 11:1) were passed through the flow tube at 172.degree. 
C. under a pressure of 12.5 bars. 
The effluent reaction mixture was cooled to 0.degree. C. at atmospheric 
pressure and analyzed gas-chromatographically. The space/time-yield was 
found to be 71 g Ac.sub.2 O per liter per hour. The yield of Ac.sub.2 O, 
based on the ester used, was 30% and the selectivity 96%. 
The carbonylation reaction was effected over a period of 100 hours under 
these reaction conditions; the performance of the carrier-supported 
catalyst could not be found to have been reduced. 
EXAMPLE 10 
2 ml (1.86 g) methyl acetate, 0.5 ml (1.14 g) methyl iodide and 1.7 g 
catalyst No. 7 were reacted in the autoclave with carbon monoxide at 
180.degree. C. under a CO-pressure of 20 bars. After a reaction period of 
1 hour, the catalyst performance was found to be 300 g Ac.sub.2 O per g Rh 
hour. The yield of Ac.sub.2 O, based on the ester used, was 62% and the 
selectivity 95%. 
EXAMPLE 11 
1.86 g dimethylether, 0.5 ml (1.14 g) methyl iodide and 1.7 g catalyst No. 
7 were reacted in the autoclave with carbon monoxide at 180.degree. C. 
under a CO-pressure of 20 bars. After a reaction period of 1 hour, the 
catalyst performance was found to be 100 g Ac.sub.2 O per g Rh per hour. 
The yield of Ac.sub.2 O, based on the ether used, was 20.6% and the 
selectivity 85%. 
EXAMPLE 12 
2 ml (1.86 g) methyl acetate, 0.5 ml (1.14 g) methyl iodide and 1.7 g 
catalyst No. 8 were reacted in the autoclave with carbon monoxide at 
180.degree. C. under a CO-pressure of 20 bars. After a reaction period of 
1 hour, the catalyst performance was found to be 243 g Ac.sub.2 O per g Rh 
per hour. The yield of Ac.sub.2 O, based on the ester used, was 50.1% and 
the selectivity 94%. 
EXAMPLE 13 
2 ml (1.86 g) methyl acetate, 0.5 ml (1.14 g) methyl iodide and 1.7 g 
catalyst No. 9 were reacted in the autoclave with carbon monoxide at 
180.degree. C. under a CO-pressure of 20 bars. After a reaction period of 
1 hour, the catalyst performance was found to be 250 g Ac.sub.2 O per g Rh 
per hour. The yield of Ac.sub.2 O, based on the ester used, was 55.0% and 
the selectivity 95.5%. 
Description of catalyst preparation 
In each particular case, the catalyst carrier was activated by drying it 
over a period of 10 hours at 200.degree. C. under a pressure of about 
0.133 millibar. All syntheses were run in the presence of nitrogen with 
exclusion of oxygen and water, and all reagents were previously dried 
using molecular sieve 4 A. 
The following abbreviations are used hereinafter 
.phi.=C.sub.6 H.sub.5 -- 
dpe=.phi..sub.2 P--CH.sub.2 CH.sub.2 --P.phi..sub.2 ; dpen=.phi..sub.2 
P--CH.dbd.CH--P.phi..sub.2 
dpb=.phi..sub.2 P--(CH.sub.2).sub.4 --P.phi..sub.2 
Tetraphos-1=.phi..sub.2 PCH.sub.2 CH.sub.2 P.phi.CH.sub.2 CH.sub.2 
P.phi.CH.sub.2 CH.sub.2 P.phi..sub.2 
Catalyst No. 1 
Al.sub.2 O.sub.3 ] [Rh(dpe).sub.2 ].sup.+ Cl.sup.- 
3 g activated aluminum oxide balls (99% Al.sub.2 O.sub.3) which had a 
diameter of 3 mm, an inner BET-surface area of 125 m.sup.2 /g a pore 
volume of 0.9 ml/g were added to 150 mg (16 mg Rh) compound of the formula 
[Rh(dpe).sub.2 ]Cl (melting point=217.degree. C.; prepared from 
1,2-bis-(diphenylphosphine)ethane and dichlorotetracarbonyldirhodium, cf. 
A. Sacco et al., J. Chem. Soc. (London), (1964), 3274; for prepartion of 
[Rh(CO).sub.2 Cl].sub.2 from RhCl.sub.3.3H.sub.2 O and CO-gas, see J. A. 
McCleverty et al., Inorg. Synth. 8 (1966), page 211; for preparation of 
.phi..sub.2 PCH.sub.2 CH.sub.2 P.phi..sub.2, see W. Hewertson et al., J. 
Chem. Soc. (London), (1962), 1490) dissolved in 100 ml dichloromethane, 
under N.sub.2. 
The yellow suspension was heated to boiling while stirring and refluxed 
over a period of 12 hours after which the dichloromethane was found to 
have been completely decolorized. Next, the dichloromethane was removed 
under reduced pressure and the catalyst was dried over a period of 8 hours 
at 85.degree. C. under 1.13 millibars. 
Yellow pellets containing 0.44 wgt % Rh were obtained. 
Catalyst No. 2 
Al.sub.2 O.sub.3 ] [Rh(dpe).sub.2 ].sup.+ BF.sub.4.sup.- 
3 g activated aluminum oxide balls (99% Al.sub.2 O.sub.3) which had a 
diameter of 3 mm, an inner BET-surface area of 125 m.sup.2 /g and a pore 
volume of 0.9 ml/g were added to 100 mg (10.4 mg Rh) compound of the 
formula [Rh(dpe).sub.2 ]BF.sub.4 (melting point=270.degree. C.; prepared 
the same way as catalyst No. 1 but with an additional anion exchange with 
AgBF.sub.4 for increasing the performance; cf. B. R. James et al., Can. J. 
Chem. 57, 180 (1979)) dissolved in 100 ml dichloromethane under N.sub.2. 
The yellow suspension was heated to boiling while stirring, refluxed over 
a period of 12 hours after which the dichloromethane was found to have 
been completely decolorized. Next, the dichloromethane was removed under 
reduced pressure and the catalyst was dried for 8 hours at 85.degree. C. 
under 1.13 millibars. 
Yellow pellets containing 0.32 wgt % Rh were obtained. 
Catalyst No. 3 
SiO.sub.2 ] [Rh(dpe).sub.2 ].sup.+ BF.sub.4.sup.- 
4 g activated silicon dioxide (98% SiO.sub.2) which had a diameter of 3 mm, 
an inner BET-surface area of 280 m.sup.2 /g and a pore volume of 0.95 ml/g 
was added to 193 mg (20.1 mg Rh) compound of the formula [Rh(dpe).sub.2 
]BF.sub.4 dissolved in 100 ml dichloromethane under N.sub.2. The yellow 
suspension was heated to boiling while stirring and refluxed over a period 
of 12 hours after which the dichloromethane was found to have been 
completely decolorized. Next, the dichloromethane was removed under 
reduced pressure and the catalyst was dried for 8 hours at 85.degree. C. 
under 1.13 millibars. 
Yellow pellets containing 0.47 wgt % Rh were obtained. 
Catalyst No. 4 
Al.sub.2 O.sub.3 ] [Rh(dpb)(CO)Cl].sub.2 
5.3 g activated aluminum oxide balls (99% Al.sub.2 O.sub.3) which had a 
diameter of 3 mm, an inner BET-surface area of 125 m.sup.2 /g and a pore 
volume of 0.9 ml/g were added to 29 mg (5.04 mg Rh) compound of the 
formula [Rh(dpe)(CO)Cl].sub.2 (melting point=182.degree. C.; prepared from 
1,4-bis-(diphenylphosphine)butane and dichlorotetracarbonyldirhodium; cf. 
A. R. Sanger, J. Chem. Soc. Dalton Trans (1977), 120) dissolved in 50 ml 
dichloromethane, under N.sub.2. The yellow suspension was heated to 
boiling while stirring and refluxed over a period of 18 hours after which 
the dichloromethane solvent was found to have been completely decolorized. 
Next, the dichloromethane was removed under reduced pressure and the 
catalyst was dried for 8 hours at 85.degree. C. under 1.13 millibars. 
Yellow pellets containing 0.08 wgt % Rh were obtained. 
Catalyst No. 5 
##STR3## 
6.3 g activated chromium/aluminum oxide cylinders (5.29 g Al.sub.2 O.sub.3 
+1.01 g Cr.sub.2 O.sub.3) with the dimensions of 4.times.4 mm and with an 
inner BET-surface area of 68 m.sup.2 /g were added to 200 mg (20.9 mg Rh) 
compound of the formula [Rh(dpe).sub.2 ]BF.sub.4 dissolved in 100 ml 
dichloromethane, under N.sub.2. The green suspension was heated to boiling 
while stirring and refluxed over a period of 24 hours after which the 
dichloromethane was found to have been completely decolorized. Next, the 
dichloromethane was removed under reduced pressure and the catalyst was 
dried for 8 hours at 85.degree. C. under 1.13 millibars. Green pellets 
containing 0.3 wgt % Rh were obtained. 
Catalyst No. 6 
Al.sub.2 O.sub.3 ] [Rh(tetraphos I)].sup.+ PF.sub.6 .sup.- 
3.5 g activated aluminum oxide balls (99% Al.sub.2 O.sub.3) which had a 
diameter of 3 mm, an inner BET-surface area of 125 m.sup.2 /g and a pore 
volume of 0.9 ml/g were added to 100 ml (11 mg Rh) compound of the formula 
[Rh(tetraphos-I)].sup.+ PF.sub.6.sup.- (melting point=314.degree. C.; 
prepared from (P.phi..sub.3).sub.3 RhCl and tetraphos-I; cf. R. B. King et 
al., Inorg. Chem. Vol. 10 (1971), page 1851 et seq) dissolved in 50 ml 
dichloromethane, under N.sub.2. The yellow suspension was heated to 
boiling while stirring and refluxed over a period of 16 hours after which 
the dichloromethane was found to have been completely decolorized. Next, 
the dichloromethane was removed under reduced pressure and the catalyst 
was dried for 8 hours at 85.degree. C. under 1.13 millibars. 
Yellow pellets containing 0.3 wgt % Rh were obtained 
Catalyst No. 7 
##STR4## 
3 g activated aluminum oxide balls (99% Al.sub.2 O.sub.3) which had a 
diameter of 3 mm, an inner BET-surface area of 125 m.sup.2 /g and a pore 
volume of 0.9 ml/g were added to 100 mg (10.4 mg Rh) compound of the 
formula [Rh(dpe).sub.2 ]BF.sub.4 and 100 mg (9.25 mg Cr) compound of the 
formula [Cr(dpe)(CO).sub.4 ] (prepared as described by J. Chatt et al., J. 
Chem. Soc. (London) 1961, pages 4980 et seq.) dissolved in 100 ml 
dichloromethane, under N.sub.2. The yellow suspension was heated to 
boiling while stirring and refluxed over a period of 12 hours after which 
the dichloromethane was found to have been completely decolorized. Next, 
the dichloromethane was removed under reduced pressure and the catalyst 
was dried for 8 hours at 85.degree. C. under 1.13 millibars. Yellow 
pellets containing 0.31 wgt % Rh and 0.28 wgt % Cr were obtained. 
Catalyst No. 8 
##STR5## 
0.1 g sodium iodide dissolved in 30 ml acetone was added while stirring to 
3 g activated aluminum oxide balls (99% Al.sub.2 O.sub.3) which had a 
diameter of 3 mm, an inner BET-surface arae of 125 m.sup.2 /g and a pore 
volume of 0.9 ml/g, and the whole was heated to boiling, and refluxed over 
a period of 48 hours. Next, the solvent was removed and the catalyst balls 
were dried for 8 hours at 85.degree. C. under 1.13 millibars. 
The rhodium was applied as described hereinabove for catalyst No. 2 
Yellow pellets containing 0.31 wgt % Rh and 3.12 wgt % NaI were obtained. 
Catalyst No. 9 
Al.sub.2 O.sub.3 ] [Rh(dpen).sub.2 ].sym.ClO.sub.4 .crclbar. 
100 mg (10.3 mg Rh) compound of the formula [Rh(dpen).sub.2 ].sym. 
ClO.sub.4 .crclbar. (prepared as described by W. A. Fordyce et al., Inorg. 
Chem. 1982, 21, pages 1455-61) dissolved in 100 ml dichloromethane was 
added under N.sub.2 to 3 g activated aluminum oxide balls (99% Al.sub.2 
O.sub.3) which had a diameter of 3 mm, an inner BET-surface area of 125 
m.sup.2 /g and a pore volume of 0.9 ml/g. The light yellow suspension was 
heated to boiling and refluxed over a period of 12 hours after which the 
solvent was found to have been completely decolorized. Next, the solvent 
was removed under reduced pressure and the catalyst was dried for 8 hours 
at 85.degree. C. under 1.13 millibars. Yellowish pellets containing 0.33 
wgt % Rh were obtained.