Reduced polymer formation in disproportionation reaction by addition of CO to feed

In an olefin disproportionation reaction, the formation of undesirable polymer is inhibited by the inclusion of a small amount of carbon monoxide in the feed.

BACKGROUND OF THE INVENTION 
This invention relates to the disproportionation of olefin hyrocarbons. 
By disproportionation is meant the conversion of an olefin hydrocarbon to a 
product having a different number of carbon atoms. In one aspect, this 
involves the reaction of two similar molecules to give a mixture of 
products having respectively a greater and a lesser number of carbon atoms 
than the starting material. For instance, two molecules of 
4-vinylcyclohexene react to give bis-cyclohexenylethylene and ethylene. In 
a second embodiment, a cyclic olefin and a second olefin serve as feed 
components to give cleavage of the cyclic olefin which may result in 
either different products or, assuming the conversion is complete a single 
product as for instance in the reaction of ethylene and 
1,5,9-cyclododecatriene to give 1,5-hexadiene. In a third aspect, a 
mixture of olefins as for instance 1-hexene and 1-octene react to give 
5-decene, 5-dodecene, and 7-tetradecene. 
In these reactions, it is readily apparent that the presence of olefinic 
materials carries with it the constant potential for formation of 
undesirable polymeric products which both reduce the production levels of 
the desired products and cause plugging of the reaction equipment. These 
polymeric products may be formed from the starting reactants, 
intermediates formed during the reaction or the final product or any 
combination thereof. 
SUMMARY OF THE INVENTION 
It is an object of this invention to reduce or eliminate polymer formation 
in olefin disproportionation reactions; 
It is a further object of this invention to avoid plugging of reaction 
apparatus in olefin disproportionation reactions; 
It is yet a further object of this invention to reduce or eliminate 
plugging in olefin disproportionation reactions without adversely 
affecting selectivity or conversion; and 
It is yet a further object of this invention to provide a process for high 
selectivity, high conversion olefin disproportionation reactions. 
In accordance with this invention, carbon monoxide is introduced along with 
the feed in an olefin disproportionation reaction. 
DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Olefin disproportionation reactions are generally known, as disclosed in 
Banks, U.S. Pat. No. 3,261,879, the disclosure of which is hereby 
incorporated by reference. A more specific reaction to produce 
bis-cyclohexenyl olefins is disclosed in Crain, U.S. Pat. No. 3,463,828, 
the disclosure of which is hereby incorporated by reference. 
The catalysts useful in this invention are conventional olefin 
disproportionation catalysts as disclosed in said Banks and Crain patents. 
The preferred catalyst in this invention is molybdenum oxide used alone or 
more preferably in combination with cobalt oxide, (generally referred to 
as "cobalt-molybdenum" catalyst) which catalyst is generally supported on 
a material such as alumina. Also suitable is tungsten oxide generally 
supported on a support such as silica. These molybdenum, 
cobalt-molybdenum, or tungsten catalysts are readily available as 
commercial products. Examples of suitable commercial catalysts other than 
those used in the examples are: 
______________________________________ 
Composition Manufacturer (#) 
______________________________________ 
3% CoO; 12% MoO.sub.3 ; 85% Al.sub.2 O.sub.3 
Harshaw 0603; 
3% CoO; 11% MoO.sub.3 ; 86% Al.sub.2 O.sub.3 
Nalco 471; and 
10% MoO.sub.3 ; 90% Al.sub.2 O.sub.3 
Harshaw 1201T. 
______________________________________ 
The invention is suitable for reducing polymer formation in the 
disproportionation of any monomer which is susceptible to 
disproportionation. The examples of such monomers are set out in said 
Banks and Crain patents and also in Reusser, U.S. Pat. No. 3,836,480, the 
disclosure of which is hereby incorporated by reference. Briefly, 
compounds suitable for disproportionation according to the invention are 
acyclic 1- and 2-alkenes, alkyl, and aryl derivatives thereof having from 
3 to 30, preferably 4-20 carbon atoms per molecule. Some specific examples 
of such olefins are propylene, 1-butene, 2-butene, 1-pentene, 2-pentene, 
1-hexene, 2-heptene, 1-octene, 2-nonene, 1-dodecene, 2-tetradecene, 
1-hexadecene, 2-methyl-1-butene, 2-methyl-2-butene, 3-methyl-1-butene, 
1-phenylbutene-2, and 3-heptene. To generalize with respect to feed, 
C.sub.3 -C.sub.30 acyclic, cyclic and bicyclic mono-, di-, or polyolefin 
hydrocarbons preferably those which are nonconjugated are suitable. This 
encompasses compounds such as 1,5,9-cyclododecatriene and cyclododecene 
reacted with ethylene and cross-reactants, 1-hexene and 1-octene. 
Particularly suitable are substituted compounds of the general formula 
##STR1## 
where n equals 1 to 27 and R is 1 or more of the following substituents: 
alkyl, cycloalkyl, aryl, and alkenyl. This encompasses the preferred 
reactant vinyl cyclohexene and more broadly the alkenyl substituted 
cycloalkenes shown in said Crain patent. 
Thus, the invention is of particular utility in a method for synthesizing 
bis(cycloalkenyl)-substituted olefins which comprises passing an 
alkenyl-substituted cycloalkene having the formula 
##STR2## 
wherein one R' is 
##STR3## 
wherein the remaining R's are selected from the group consisting of 
hydrogen and alkyl radicals containing from 1 to 10 carbon atoms, wherein 
m is 4, and wherein the total carbon atoms in one of said 
alkenyl-substituted cycloalkenes does not exceed 20 to a reaction zone 
along with 0.1 to 50 weight percent CO based on the weight of said 
alkenyl-substituted cycloalkene; contacting said alkenyl-substituted 
cycloalkene with an effective catalytic amount of a catalyst resulting 
from the admixture of one of molybdenum oxide, cobalt oxide, tungsten 
oxide, molybdenum hexacarbonyl, tungsten hexacarbonyl, ammonium tungstate, 
and molybdenum, cobalt, and tungsten materials convertible to the oxide on 
calcination and one of alumina- and silica-containing support under 
conditions of temperature and pressure sufficient to form 
bis(cycloalkenyl)-substituted olefins of the formula 
##STR4## 
wherein R is at least one member selected from the group consisting of 
hydrogen and alkyl containing from 1 to 10 carbon atoms and recovering 
said bis(cycloalkenyl) substituted olefin. Here, the catalyst may consist 
essentially of alumina and between 0.1 and 30 weight percent of molybdenum 
oxide. Optionally, the catalyst may contain 0.1 to 10 weight percent 
cobalt oxide, 0.1 to 30 weight percent molybdenum oxide and the rest 
alumina. 
As an illustrative embodiment, 1,2-bis(3-cyclohexen-1-yl) ethylene is 
formed by contacting 4-vinylcyclohexene with a catalyst consisting 
essentially of from 3 to 15 weight percent molybdenum oxide, from 1 to 5 
weight percent cobalt oxide, and from 96 to 80 weight percent aluminum 
oxide which aluminum oxide has a surface area ranging from 25-300, 
preferably 50-250 square meters per gram at a temperature ranging from 
75.degree.-200.degree. C. for a period of time sufficient to obtain a 25 
percent conversion and recovering the 1,2-bis(3-cyclohexen-1-yl)ethylene 
product. 
The reaction conditions are conventional in the art and more specifically 
can be as set out in said Banks patent. 
The process can be carried out either batchwise or continuously, using a 
fixed catalyst bed, or a stirrer equipped reactor or other mobile catalyst 
contacting processes as well as any other well known contacting technique. 
Preferred reaction conditions, for instance temperature, pressure, and 
flow rates vary somewhat depending on the specific catalyst composition, 
the particular feed olefin, and the desired products. The process is 
carried out generally at a temperature of 77.degree.-572.degree. F. 
(25.degree.-300.degree. C.), preferably 250.degree.-400.degree. F. 
(121.degree.-204.degree. C.). Pressure can be any convenient pressure, for 
instance 0 to 1500 psig. Although the disproportionation reaction of this 
invention is essentially independent of pressure, for most economical 
operation considering combination with other steps of a complete plant 
operation including, for example, product separation and recovery, a 
pressure range of 50 to 500 psig can be used most conveniently. 
The operable range of contact time for the process of this invention 
depends primarily upon the operating temperature and the activity of the 
catalyst which is influenced by surface area, promoter concentration, and 
activation temperature. In general, the distribution of products is not 
drastically altered by variation in contact time. However, long contact 
times in general favor the production of larger proportions of higher 
molecular weight products. In general, shorter contact times are 
associated with higher temperatures, but when larger amounts of higher 
molecular weight products are desired, a suitable combination of contact 
time and temperature is selected. 
A weight hourly space velocity of 0.1 to 1,000, preferably 0.5 to 20, more 
preferably 1 to 10 parts by weight of hydrocarbon feed per part by weight 
of catalyst is suitable. Higher space velocities in general are associated 
with higher reaction temperatures. In general contact times in the range 
of 0.5 seconds to 10 hours are used. 
The process may be carried out in the presence or absence of an inert 
diluent with the amount of diluent generally ranging from 0 to 90 volume 
percent of the reaction mixture. Suitable diluents include saturated 
hydrocarbons such as alkanes and cycloalkanes. Some examples are 
cyclohexane, cycloheptane, hexanes, octanes, decalin, and mixtures 
thereof. 
Of course, the important consideration is the contact time between active 
catalyst and monomer. Hence, in the case of tungsten catalysts which are 
more likely to contain inert carrier material, higher space hourly weight 
velocities of feed are generally utilized. 
Carbon monoxide is used in an amount within the range of 0.1 to 50, 
preferably 0.5 to 25 weight percent based on the weight of the olefin 
feed. In the event a diluent is used, the calculation is still based on 
the weight of the feed only, without regard to the diluent. The carbon 
monoxide is simply metered into the reaction vessel, preferably along with 
the feed. In a less preferred embodiment, it can be introduced as a 
separate stream into the vessel. As with the feed itself, an inert diluent 
can be used in order to facilitate the metering of the carbon monoxide. 
Gases such as nitrogen, argon and other inert gases could be used for such 
purpose, however generally, there will be no diluent with the carbon 
monoxide. 
After the reaction period, the products are separated and isolated using 
conventional techniques.

EXAMPLE I 
The reactor employed in Example I was a 1/2".times.20" stainless steel 
pipe, which had a pre-heat zone packed with glass beads and a post 
reaction zone packed with glass beads. Thus, the top 71/2-8" of the pipe 
was packed with glass beads, followed by a 1/2-1" glass wool plug. Then, 
about 20 mL of catalyst (filling about 8" of pipe) were loaded followed by 
another glass wool plug, and the remainder of the bed (about 4-41/2") 
filled with glass beads. 
Catalysts employed in the following examples are identified as follows: 
______________________________________ 
Catalyst 
Composition Manufacturer (#) 
______________________________________ 
A 4% CoO; 15% MoO.sub.3 ; 
American Cyanamid (HDS-2) 
81% Al.sub.2 O.sub.3 
A' A + 0.25 wt. % KOH 
A" A + 0.75 wt. % KOH 
______________________________________ 
Typically, catalyst was activated by heating in air for 2-3 hours at about 
540.degree. C. (1000.degree. F.), then pre-reduced by introducing a carbon 
monoxide flow for about 15 minutes while maintaining catalyst at 
540.degree. C. Reactor was then cooled to desired reaction temperature, 
typically 130.degree. C. (267.degree. F.) under a CO atmosphere, then 
olefin feed introduced. 
Samples were analyzed by gas liquid chromatography (glc) employing a 
1/8".times.20' 10% SE-30 on Chromosorb packed column. 
Conversion/selectivity values were calculated using glc area percent. 
Thus, conversion is determined by subtracting starting material area 
percent from 100. Selectivity is determined by dividing total area percent 
for primary disproportionation products by the conversion. 
The disproportionation reactor was loaded with 21 gm of catalyst A' (0.25 
wt. % KOH (based on K metal) treated American Cyanamid HDS-2 catalyst). An 
equimolar mixture of 1-hexene and 1-octene was introduced at a flow rate 
of about 30 mL/hr. After about 4 hours on stream, polymer formation was 
apparent as evidenced by reactor plugging giving pressure rise and 
precipitation of white solid in the effluent. The white precipitate was 
analyzed by infrared as a KBr disc and showed absorptions at 720, 1370, 
1460, 2850, and 2920 cm.sup.-1 which indicate a long-chain 
polyethylene-like hydrocarbon material. 
Several more experiments were carried out with the same feed at a variety 
of WHSV, reaction times, pressures, and the like in the absence and 
presence of CO as co-feed. Results are summarized in Table I. 
TABLE I 
__________________________________________________________________________ 
Feed Rate** 
Reaction Conditions 
Run Reactant Olefin, 
CO, Temp., 
Press., 
Time, Total 
No. 
Catalyst 
(mol ratio) mL/hr 
mL/min 
.degree.C. 
psig 
hr WHSV 
Conversion 
Selectivity 
Polymer 
__________________________________________________________________________ 
1 A' 1-hexene/1-octene (1:1) 
30 -- 130 100 4 1 39.9 57.4 Yes 
2 A" 1-hexene/1-octene (1:1) 
30 -- 130 100 4 1 59.2 37.7 Yes 
3 A"* 1-hexene/1-octene (1:1) 
30 -- 130 100 6 1 20.8 34.6 Yes 
4 A' 1-hexene/1-octene (1:1) 
30 64 (23) 
130 100 6 1 54.9 59.4 None 
5 A 1-hexene/1-octene (1:1) 
30 64 (23) 
130 100 3 1 55.4 79.6 None 
6 A 1-hexene/1-octene (1:1) 
145 35 (2.6) 
130 75 2 5 55.7 76.7 None 
7 A 1-hexene/1-octene (1:1) 
30 64 (23) 
130 100 2 1 72.3 61.7 None 
8 A" 1-hexene/1-octene (1:1) 
30 50 (18) 
130 85 4 1 63.0 50.6 None 
9 A 1-hexene/1-octene (1:3) 
150 42 (3.0) 
130 80 3 10 26.9 84.8 None 
__________________________________________________________________________ 
*Catalyst not CO pretreated. 
**The reactant feed rate is in milliters of liquid olefin per hour, 
whereas the CO is in milliters of gaseous CO per hour. The numbers in () 
are the weight percent CO based on weight of feed. 
These results demonstrate that the presence of CO in the olefin feed 
introduced to the reactor prevents polymer formation during the 
disproportionation reaction. Conversions and selectivities are comparable 
to or better than results obtained in the absence of CO co-feed. As is 
shown by Run 3, the problem of polymer formation exists whether or not the 
catalyst is given a CO pretreatment. A separate matter from use of CO in 
the feed is the presence or absence of CO treatment of the catalyst 
itself. 
EXAMPLE II 
The self-reaction of vinyl-cyclohexene over a disproportionation catalyst 
to give bis(cyclohexenyl)ethylene was carried out with a CO-activated 
cobalt molybdate catalyst. The general procedure described above was 
employed, except 40 g of catalyst was employed with no glass beads. The 
reaction conditions employed and experimental results are presented in 
Table II. 
TABLE II 
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Feed Rates* Reaction Conditions 
Run 
VCH, Temp., 
Press., 
Time, 
No. 
mL/hr 
CO, mL/min 
.degree.C. 
psig 
hr WHSV 
Conversion 
Selectivity 
Polymer 
__________________________________________________________________________ 
1 50 -- 130 50 2 1 20.2 89.5 Yes 
2 140 110 (7.1) 
130 50 2 3 &lt;2 77 None 
2a 
50 110 (20) 
130 50 2 1 3.5 83 None 
3 45 40 (8) 
130 50 5 1 8.2 81.5 None 
4 50 40 (7.2) 
130 50 4 1 14.7 87.8 None 
5 50 35 (6) 
130 50 4 1 10.2 88.1 None 
6 50 35 (6) 
150 50 4.5 1 16.5 87.5 None 
7 50 35 (6) 
150 50 2 1 18.1 95.6 None 
__________________________________________________________________________ 
*The reactant feed rate is in milliters of liquid olefin per hour, wherea 
the CO is in milliters of gaseous CO per hour. The numbers in () are the 
weight percent CO based on weight of feed. 
This example demonstrates the effectiveness of low levels of CO addition to 
the reactant feed for elimination of polymer formation during the desired 
disproportionation reaction. 
EXAMPLE III 
Freshly distilled 1,5,9-cyclododecatriene was passed through a guard bed 
containing about 80 g of 13X molecular sieve and 67 g of MgO (equal 
volumes), then reacted with an excess of ethylene at about 345.degree. C. 
and 30 WHSV (based on active catalyst) over 1.5 g WO.sub.3.SiO.sub.2 
(Davison SMR-7-2870) admixed with 4.5 g Al.sub.2 O.sub.3 (Norton SA-5123). 
Catalyst was pre-treated as described above, heating in air maintained for 
about 14 hours before CO pre-treatment and cooling to reaction 
temperature. As indicated in Table III, Run 1, in the absence of CO, 
inhibitor-free reactant causes reactor plugging after about 3-4 hours on 
stream. Other runs in the absence of CO employing variously purified feeds 
show variable incidence of polymer formation. When reaction is carried out 
in the presence of CO co-feed, polymer formation is not observed. 
TABLE III 
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Feed Rate.sup.e 
Run 
CDT, 
Ethylene, Ethylene/CDT 
Press., 
No. 
mL/hr 
mL/hr 
CO, mL/min 
mol ratio 
psig 
Time, hr 
Conversion 
Selectivity 
Polymer 
__________________________________________________________________________ 
1 55.sup.a,b 
66 -- 10/1 50 2 26.8 70.9 None 
3 25.3 31.7 None 
3.5 25.0 17.3 Yes 
2 55.sup.c,b 
66 -- 10/1 50 5 91.9 64.1 None 
12 82.5 51.3 None 
3 55.sup.c 
66 -- 10/1 50 3 89.8 61.9 None 
5 80.7 57.9 Yes 
7 83.4 52.5 None 
4 55.sup.b 
66 -- 10/1 50 2 73.5 32.5 None 
3 45.5 24.9 Yes 
5 55.sup.b 
66 50 (3) 10/1 50 4.5 67.2 43.5 None 
9 45.5 32.9 None 
12 32.2 24.2 None 
6.sup.d 
45.sup.a 
55 42 (3) 10/1 50 4.5 87.6 56.7 None 
12 82.4 50.6 None 
7 55.sup.b 
102 50 (2) 15/1 500 4 74.3 36.0 None 
11 74.1 34.8 None 
8.sup.d 
45.sup.b 
82.5 10 (0.5) 
15/1 500 4 77.5 38.5 None 
9 55.sup.c 
66 50 (3) 10/1 50 4.5 85.6 44.4 None 
12 76.9 36.1 None 
__________________________________________________________________________ 
.sup.a Distilled 
.sup.b Percolated through guard bed (105 g 13.times. molecular sieve; 45 
MgO). 
.sup.c Flash distilled. 
.sup.d 17% less active catalyst used (1.25 g vs. 1.5 g 
WO.sub.3.SiO.sub.2). 
.sup.e The reactant feed rate is in milliters of liquid olefin per hour, 
whereas the CO is in milliters of gaseous CO per minute. The number in () 
are the weight percent CO based on weight of feed. 
This example illustrates the effectiveness of low levels of CO for 
reduction of polymer formation in the disproportionation of 
1,5,9-cyclododecatriene in the presence of ethylene. None of the runs 
employing CO as co-feed evidenced polymer plugging or precipitation. 
While this invention has been described in detail for the purpose of 
illustration, it is not to be construed as limited thereby but is intended 
to cover all changes and modifications within the spirit and scope thereof 
.