GB2207613A - Oligomerisation-dimerisation catalyst - Google Patents

Abstract

A catalyst comprising a fluorinated gamma-alumina impregnated by a bis (cyclodiene) nickel (o) chelate, preferably bis (cyclooctadiene-1,5) nickel (o) chelate, can be used as a catalyst in the oligomerisatlon of propylene, butylene or of a propylene/butene mixture, for example the dimerisation of butene-1 and/or butene-2.

Description

Oligomerisation - Dimerisation Catalyst This invention relates to catalysts suitable for oligomerising and dimerising olefins and to methods of oligomerisation and dimerisation.

Oligomerisation of low molecular weight olefins such as ethylene and propylene and to a lesser extent butene-1 and butene-2 is well known - see W Keim, A Behr, M Röper Compr Organomet Chem 8 371. Most of the literature references are concerned with homogeneous catalyst systems. The known heterogeneous catalysts usually require a high temperature calcination step, preferably in situ in view of the high sensitivity to air of the resulting active catalyst. Furthermore such catalysts have relatively high amounts of transition metals deposited on supports. These two factors tend to increase the cost of the heterogeneous catalyst. According to this invention such disadvantages are substantially eliminated by the use of a catalyst comprising a fluorinated /-alumina impregnated with bis (cyclodiene) nickel (o) chelate.Also in accordance with this invention propylene, a butene or a mixture of propylene and a butene are oligomerised, (for example butene-l and/or butene-2 is dimerised) by a process comprising heating the olefin or olefin mixture in the presence of a catalyst formed by the impregnation of fluorinated alumina with a bis (cyclodiene) nickel (o) chelate and obtaining the oligomerised or dimerised olefin from the reaction mixture.

The fluorinated /-alumina is impregnated with a bis (cyclodiene) nickel (o) chelate. The chelate can be derived from various cyclodienes for example cyclopentadiene, cyclohexadiene-1,3 cyclohexadiene-1,4, cyclooctadiene-1,3, cyclooctadiene-1,4 and cyclooctadiene-1,5. The preferred cyclodiene from which the chelate is derived is cyclooctadiene-1,5.

It is convenient to impregnate the fluorinated t-alumina by contacting pellets of fluorinated 3/ -alumina in toluene and adding the bis (cyclodiene) nickel (o) chelate (usually 1 to 5 wt% based on Y-alumina) and allowing to stand for a period of time, for example from 1 to 50 hours. The impregnated pellets can then be filtered, thoroughly washed with portions of dry toluene and dried under a vacuum. The catalyst can be handled and stored under an inert atmosphere for example nitrogen or argon.

In accordance with the process of this invention propylene, a butene or a mixture of propylene and a butene can be oligomerised. It is found that propylene can be oligomerised usually at over 80% conversion to hexenes (usually 60 to 70 wt%), nonenes (usually 20 to 40 wt%), dodecenes (usually less than 10 wt%) and pentadecenes (usually less than 5 wt%). A mixture of propylene and a butene (butene-l or butene-2) can be oligomerised usually at a conversion of over 70% and often over 80% to hexenes (usually 5 to 10 wt%), heptenes (usually 25% to 30% wt%), octenes (usually 35 to 45 wt,%) nonenes (usually less than 5 wt%) decenes (usually 5 to 10 wt%), undecenes (usually 5 to 10 wit8) dodecenes (ususally 5 to 10 wt%) and usually less than 5 wt% of olefins of longer chain length than dodecene.

In a preferred embodiment of the process of this invention butene-1 and/or butene-2 can be dimerised usually at a conversion of over 60% and often over 70%, to n-octene (usually 10 to 20 wt%), methyl heptenes (usually 60 to 70 wt%) and dimethyl hexenes (usually 15 to 25 wt%).

In order to achieve the oligomerisation, e.g.

dimerisation, of the olefin or olefin mixture the conversion may be effected by introducing the feed and catalyst into an autoclave and heating the mixture for a period of time, preferably 3 to 8 hours, for example about 5 hours. The temperature of the reactants should preferably be from 50 to 1500C, for example about 700C.

The ratio of olefin or olefin mixture to catalyst can vary, but usually it is between 15:1 to 25:1 by weight, for example about 20:1 by weight.

The pressure to be employed in performing the process of this invention should be sufficient to maintain the olefin in the liquid phase at the operating temperature and is preferably in the range of 2 to 40 bars.

It has been found that spent catalyst recovered under an inert atmosphere maintains its good performance in subsequent dimerisations.

The invention is illustrated by the following Examples.

Example 1 A fluorinatedlumina containing 10 weight % acid was dried for 24 hours at 500C under vacuum. In different preparations pellets of the dried fluorinated t-alumina were impregnated with bis-(cyclooctadiene-1,5) nickel (o) in dry toluene for periods of time varying from 2 to 48 hours.

Differing amounts of chelate impregnated onto the fluorinated V-alumina were achieved. in the preparations. The impregnation was followed by filtration, thorough washing with 30 ml aliquots of dry toluene (3 times) and drying for 36 hours under 10 2 mm Hg pressure at ambient temperature. Each catalyst preparation was handled and stored under an inert argon atomosphere and used for testing without further treatment.

Example 2-19 The various catalyst preparations obtained in Example 1 were used for dimersing butene-1 and for oligomerising propylene, a propylene/propane mixture and a propylene/butene-1 mixture. The composition of the catalyst used, the reaction conditions and the results obtained are given in Tables 1 and 2.

For comparison purposes some dimerisation reactions were carried out using the t -alumina support without Ni (Example 2 to 4 and 12). It can be seen that higher conversions and selectively and improved branchiness are obtained when using the catalyst of this invention.

T A B L E 1 DIMERISATIONS (1) Amount of Nickel in total T Conversion Selectivity WT% C8= ISOMER COMPOSITION WT% (4) Example Catalyst Catalyst Olefin C WT% C8 C12 3-br 2br 1-br lin.

2 F-Al2O3 - C4=-1 70 5.0 54.0 38.3 - - - 3 F-Al2O3 - C4=-1 150 40 60.3 22.0 0.80 97.35 1.60 0.25 4 F-Al2O3(2) - C4=-1 150 61 39.9 33.6 1.67 88.21 9.91 0.21 5 Ni/F-Al2O3 3.8 wt% C4=-1 70 57 84.6 14.6 0.00 15.98 64.91 18.11 6 Ni/F-Al2O3 1.6 wt% C4=-1 70 73 82.3 16.2 0.00 20.59 66.28 13.13 7 Ni/F-Al2O3 1.6 wt% (3) 70 73 86.3 13.3 0.04 23.54 64.82 11.60 8 Ni/F-Al2O3 2.7 wt% C4=-1 70 65 85.7 13.3 0.00 17.59 65.48 16.93 9 Ni/F-Al2O3 2.7 wt% C4=-2trans 70 10 90 9.6 0.00 11.81 73.43 14.76 10 Ni/F-Al2O3 1.1 wt% C4=-1 70 64 85.6 13.9 0.00 21.70 64.18 14.12 11 Ni/F-Al2O3 1.1 wt% C4=-2cis/ 70 73 85.6 13.0 0.00 24.47 65.42 10.11 trans (1) Reaction conditions : 1 l autoclave; Catalyst/Feed (wt/wt ratio) : 0.05; 5 h reaction tim.

(2) Support pretreated for 3 h at 300 C.

(3) C4 raffinate, purified feed composition : 20.9wt% C4=-1; 38wt% C4=-2tr; 21wt% C4=-2-cis; 1.4wt% i-C4=; 19.5wt% C4 (butane).

(4) Br = branching T A B L E 2 PROPYLENE AND C3=/C4= OLIGOMERISATIONS T CONVERSION SELECTIVITY WT% Example Catalyst Olefin C WT% C6 C9 C12 C15 12 F-Al2O3 C3= 150 51 8.8 32.9 23.9 12.4 13 Ni/F-Al2O3 C3= 70 53.5 68.6 25.7 5.4 3.8 wt% Ni 14 Ni/F-Al2O3 C3= 70 81 45.9 39.6 13.6 spent cat (Ex 13) 15 Ni/F-Al2O3 C3=/C3 70 85 72.0 19.0 5.0 2.1 2.7 wt% Ni 40/60 wt% 16 Ni/F-Al2O3 C3= 70 99 70.6 21.5 5.8 2.1 2.7 wt% Ni C6 C7 C8 C9 C10 C11 C12 C12+ 17 Ni/F-Al2O3 C4=/C3= 70 73 7.1 28.7 40.9 1.7 5.5 6.6 5.3 4.2 spent cat (Ex 6) (3/1 molar) 18 Ni/F-Al2O3 C4=/C3= 70 84 12.0 25.1 29.7 3.0 8.2 7.3 5.7 9.0 1.3 wt% Ni (2/1 molar) (1) Reaction Condition : 1 l Stainless steel autoclave; Catalyst Feed weight ratio : 0.05; 5 h reaction time.

Claims (8)

CLAIMS:

1. A catalyst comprising a fluorinated gamma-alumina impregnated with a bis (cyclodiene) nickel (o) chelate.

2. A catalyst according to claim 1 which contains 5 to 15 wt% fluorine.

3. A catalyst according to either of claims 1 and 2 wherein the cyclodiene is cyclooctadiene-1,5.

4. A catalyst according to any one of the preceding claims which has been prepared by impregnating the gamma-alumina with 1 to 5 wt% based on the gamma-alumina of the bis (cyclodiene) nickel (o) chelate.

5. A process of oligomerising propylene, a butene or a mixture of propylene and a butene which comprises heating the olefin or olefin mixture in the presence of a catalyst according to any one of the preceding claims and obtaining the oligomerised or dimerised olefin from the reaction mixture.

6. A process according to claim 5 wherein the temperature of the oligomerisation or of the dimerisation is between 500 and 1500C.

7. A process according to either of claims 5 and 6 wherein the ratio of olefin or olefin mixture to catalyst is between 15:1 and 25:1 by weight.

8. A process according to any one of claims 5 to 7 wherein butene-1 and/or butene-2 are dimerised.