GB2254802A

GB2254802A - Catalyst composition for coupling process

Info

Publication number: GB2254802A
Application number: GB9208001A
Authority: GB
Inventors: James Stephen Staton; Ronald Craig Zumstein; Robert Bruce Agee
Original assignee: Ethyl Corp
Current assignee: Ethyl Corp
Priority date: 1991-04-19
Filing date: 1992-04-10
Publication date: 1992-10-21
Anticipated expiration: 2012-04-10
Also published as: GB2254802B; GB9208001D0

Abstract

A process for producing a granular free-flowing catalyst composition useful in coupling an alkene with an aromatic hydrocarbon having an active hydrogen on a saturated alpha -carbon. The catalyst composition formed from an alkali metal and an alkali metal carbonate is treated with a liquid inert dispersant.

Description

CATALYST COMPOSITION FOR COUPLING PROCESS This invention relates to a process for forming catalyst compositions and, more particularly, to a process for producing catalyst compositions which can be used in the coupling of alkenes with aromatic hydrocarbons having an active hydrogen on a saturated a-carbon.

U. S. Patent 4,179,580 (Cobb), European Patent 128001 (Kudoh, et al.), and Eberhardt, et al., Journal of Organic Chemistry, Vol. 30, pp. 82-84 (1965) show that it is known that supported alkali metals are useful as catalysts in the coupling of ethylenically-unsaturated hydrocarbons with aromatic hydrocarbons having an active hydrogen on a saturated a-carbon. See also U. S. Patent 4,950,831 (Staton et al.). The supported alkali metals are more effective than the corresponding unsupported alkali metals in such reactions but are still not as effective as rnight be desired.

As disclosed in Smith's U.S. Patents 4,922,054, 4,929,783, and 4,982,035, it has been found that alkenes can advantageously be coupled with a-carbon in the presence of a supported alkali metal as a catalyst and 10-100 mole %, based on the amount of the alkali metal catalyst, of an oxide of sodium, potassium, rubidium, cesium, barium, strontium, calcium, or magnesium as a co-catalyst.

U. K. Patent 1,269,280 discloses a process for the manufacture of alkyl aromatic hydrocarbons using a catalyst prepared by dispersing sodium and/or lithium or an anhydrous potassium compound. The dispersing is carried out by stirring or tumbling the molten metal with the potassium compound, the potassium compound being selected so that it does not melt, sinter or decompose at the deposition temperature.

Co-pending U.K. patent application number 91-23932.7 filed November 11, 1991, discloses a catalyst composition formed by the treatment of an alkali metal with an alkali metal carbonate.

It has now been found that a free-flowing, granular catalyst composition which is effective in catalyzing the coupling of an alkene with an aromatic hydrocarbon having an active hydrogen on a saturated a-carbon can be obtained by treating catalyst compositions formed from an alkali metal and an alkali metal carbonate with an inert liquid dispersant.

In carrying out the process of the present invention, a liquid inert dispersant is added to a mixture of an alkali metal and an alkali metal carbonate that have been admixed at a temperature sufficient to melt the alkali metal. The dispersant is added by intimately mixing it into the catalyst mixture. While the addition of such dispersant can be effected while the mixture remains at the temperature of alkali metal melting, it has been found more convenient to cool such mixture to below boiling point of the dispersant.

To be an effective dispersant, all that is required is that the material be substantially inert to the components in the catalyst composition (i.e., not react with them) and a liquid at or near the conditions employed during its addition to the alkali metal, alkali metal carbonate. Further, it must remain a liquid at or near the temperature used to separate the resulting granular free-flowing catalyst composition from the liquid inert dispersant. However, there is no need to separate the dispersant from the catalyst before use if such dispersant does not cause any problems in the subsequent reaction. Such material is in the class of aliphatic and aromatic hydrocarbons.Aliphatic hydrocarbons of use as inert liquid dispersants include those having five or more linear or branched carbon atoms in the chain or in a ring, preferably C6 to C20 linear or branched carbon atoms or mixtures of such compounds or cyclic derivatives thereof. Examples of such aliphatic hydrocarbons are hexanes (including various isomers), heptanes (including various isomers), cyclohexane, and methylcyclohexane.

Aromatic hydrocarbons of use as inert liquid dispersants include benzene, optionally substituted with one or more C1 to C6 linear or branched alkyl or halo (chloro or bromo). Examples of such aromatic hydrocarbons include benzene, toluene, xylene, mesitylene and chlorobenzene.

In adding the liquid inert dispersant to the mixture of alkali metal and alkali metal carbonate, from 0.5% to 50% by weight based on the mixture is employed.

Preferably 1% to 10%, most preferably 3% to 76roc, by weight based on the mixture is used. If too little dispersant is employed, the mixture remains as a paste, difficult to break into smaller, catalytically effective pieces. Too much dispersant will turn the catalyst into a slurry, which is hard to handle. Using the amounts disclosed above produces a moist, granular solid that flows with ease, without separation of the dispersant. Removal of the excess dispersant can be readily accomplished by conventional methods (e.g., filtration or centrifugation) producing a granular solid that flows with ease.

The alkali metal employed in the practice of the process of this invention may be lithium, sodium, potassium, rubidium, or cesium. It is preferably sodium.

The alkali metal carbonates used with the above-disclosed alkali metal are the carbonates of lithium, sodium, potassium, rubidium, or cesium. While any of the above alkali metal carbonates can be used with any of the above alkali metals, it is preferred that the alkali metal be different from the alkali metal moiety of the alkali metal carbonate. Particularly preferred are catalysts comprising sodium and potassium carbonate or potassium and sodium carbonate.

In mixing the alkali metal and the alkali metal carbonate, it is useful to have the alkali metal in the liquid (melted) form, which permits a catalyst to readily form. It is essentially a liquid heterogeneous mixture when at high temperature (the liquid metal is absorbed onto the surface of the solid) but a solid heterogeneous mixture at lower temperatures. The melting point of such mixture depends, of course, on the type of alkali metal and alkali metal carbonate, as well as the mole ratio of such components, e.g., mixtures of sodium and potassium carbonate (at a mole ratio of 1:1) melt at about 100 C. Thus, for example, a catalyst from rubidium metal and potassium carbonate is prepared by heating rubidium to about 400 C and adding potassium carbonate. The mixture is a solid at room temperature.

Among the important conditions for forming the catalysts used in the process of the present invention (aside from temperature of processing) are included the ratios of the alkali metal to the alkali metal carbonate and the size of the alkali metal carbonate granules. Thus, mole ratios of alkali metal to alkali metal carbonate used to prepare the catalyst compositions are from 0.5/1 to 4/1.

Preferably, this ratio is from 1/1, to 3/1, most preferably from 2/1 to 3/1.

The size of the granules of alkali metal carbonate must not be so coarse as to inhibit the formation of a satisfactory catalyst. Such granules merely need to be small enough to provide sufficient surface area for the liquid metal to coat the solid so that metal and carbonate can react. Thus, the size can be as large as 5mm, with smaller granules, 0.05mm, being preferred. The rate of mixing the particles is not critical in achieving an improved catalyst composition. However, the agitation rate must be sufficient to provide thorough mixing of the two phases as well as good heat transfer.

When the novel catalyst composition is employed in a coupling reaction, it is used in an amount such as to provide a catalytic amount of the alkali metal, generally 2-10 mole to, based on the amount of either of the reactants when they are utilized in equimolar amounts or on the amount of the major reactant when they are not utilized in equimolar amounts.

As in the processes of Smith, the alkene which is coupled with the aromatic hydrocarbon in the presence of the catalyst composition may be any of the alkenes which are known to be useful in such reactions, such as ethene, propene, 1-butene, 2-butene, isobutene, 1-pentene, 2-pentene, 3-methyl-1-butene, 2-methyl-2-butene, 1-hexene, 2-hexene, 3-hexene, 4-methyl- 1-pentene, 3-methyl-l-pentene, 4-methyl-2pentene, 1-heptene, 2-heptene, 2-octene, 4-nonene, 1-decene, 2-decene, 1-dodecene, 3-tetradecene, 5-hexadecene, 6-methyl-4-heptadecene or 1-cicosene. However, it is generally an alkene corresponding to the formula QQ'C = CUT,, in which Q, Q', T, and r are independently selected from hydrogen and alkyl groups of up to 20 carbons; and it is apt preferably to be an alkene of up to 20 carbons. Particularly preferred alkenes are ethene and propene.

The aromatic hydrocarbon having an active hydrogen on a saturated carbon may be any such compound that is known to be useful in such reactions, such as toluene, ethylbenzene, n-propylbenzene, isopropylbenzene, n-butylbenzene, secbutylbenzene, isobutylbenzene, n-eicosylbenzene, o-, m-, and p-xylenes, o-, m-, and p-ethyltoluenes, 1,3,5-trimethylbenzene, 1,2"3,4- and 1,2,3,5-tetramethylbenzenes, p-diisopropylbenzene, 1- and 2-methylnaphthalenes, dimethylnaphthalenes, i-ethyl- 4-n-octadecylnaphthalene, 1,4-di-n-pentyl naphthalene, 1 ,2,3,4-tetrahydronaphthalene, indan, cyclohexylbenzene, methylcyclohexylbenzene or diphenylmethane.However, it is generally a hydrocarbon corresponding to the formula RR'R"CH, in which R is an aryl group of up to 20 carbons and R' and R" are independently selected from hydrogen and alkyl and aryl groups of up to 20 carbons; and it is apt preferably to be an allrylbenzene having one or more ar-alkyl groups. A particularly preferred aromatic hydrocarbon is toluene.

The mole ratio of alkene to aromatic hydrocarbon in theSe coupling reactions varies with the particular reactants employed and the products desired, particularly since the aromatic hydrocarbon may have one or more active hydrogens, and it may be desired to react the alkene with only one or with more than one active hydrogen in the aromatic hydrocarbon. It is frequently preferred to employ the reactants in the stoichiometric amounts appropriate for the preparation of the desired product. However, either reactant can be used in excess.

The coupling reaction is conducted by heating a mixture of the alkene, the active hydrogen-containing aromatic hydrocarbon, and the novel catalyst composition under substantially anhydrous conditions at a suitable temperature, generally 100-300 C, preferably 175-200 C, to couple the reactants. It is generally conducted in the absence of a diluent or in the presence of an excess of the active hydrogencontaining aromatic hydrocarbon as the sole diluent. However, an inert diluent can be used if desired. Exemplary of such diluents are liquid alkanes, cycloalkanes, and aromatic hydrocarbons, such as pentane, hexane, isooctaine, cyclohexane, naphthalene, decahydronaphthalene, and white oils.

The catalyst compositions of the invention are advantageous in that they provide a more economically reliable composition, producing higher product yields at lower cost when used in coupling reactions than comparable more expensive catalyst compositions, e.g., sodium-potassium alloy. The coupling reactions in which these catalysts are used are particularly advantageous as a means of alkylating alkylaromatic compounds, especially alkylbenzenes, to form compounds useful as solvents, internal standards, intermediates for polymers, pharmaceuticals or pesticides.

The following examples are given to illustrate the invention and are not intended as a limitation thereof.

EXAMPLE 1 9.8 kg of powdered K2CO3 and 4.5 kg Na were added to a 1 cubic ft Paul O. Abbe jacketed sigma blade mixer equipped with screw discharge and purged with N2. The entire unit was enclosed in a N2 purged glovebqx. The blender was heated to 250 C with hot oil; mixing was started when the temperature reached 110 0C. After the temperature reached 250 C, the blender was allowed to mix for 30 minutes and then cooled to 60 " C. The top of the blender was then opened and the catalyst observed to be a homogeneous silver-colored paste. The screw discharge was started with the catalyst being discharged into a 5-gal stainless steel can on a scale.After about 10 minutes, only 7 kg of material had been discharged with the remaining catalyst adhered to the blades and walls of the blender. The discharge screw was turned off, the blender was closed and one liter of toluene was slowly fed while the contents were allowed to mix. After mixing about 5 minutes the blender was again opened and the contents observed to be a free flowing blue-gray colored powder containing free droplets of liquid NaK around 1/2 inch in diameter. The discharge screw was started and the remaining catalyst flowed freely out into the 5-gal can.

EXAMPLE 2 i) 188 grams of powdered K2CO3 and 88 grams of Na were added to a 1 liter reactor equipped with an agitator and purged with N2. The reactor was heated to 350 C with a heating mantle; mixing was started when the temperature reached 120 C. After the temperature reached 350'C, the reactor was allowed to mix for 30 minutes and then allowed to cool to 600 C. At this point, the catalyst was observed to be a homogeneous silver-colored paste. 15 grams of toluene were added while the contents were allowed to mix. After mixing about 5 minutes, the contents were observed to be a free flowing blue-gray colored powder containing free droplets of liquid NaK. The mixture was transferred to a sample jar using a small spoon.

ii) The catalyst prepared above in i) was added to a 5-gal autoclave under a N2 purged glove bag. The autoclave was sealed up and 2 grams of oleic acid and 8107 grams of toluene were added. Agitation at a tip speed of 30 ft/sec was started and the autoclave was heated to 190 C. 2985 grams of propylene were fed over a 2 hour period at a rate that maintained the autoclave pressure between 375 and 400 psig. The temperature during this feed period was maintained at 190 C. After the propylene had been added, the reaction was,allowed to continue at this temperature for an additional 2 hours while the autoclave pressure dropped to 280 psig as remaining propylene reacted. The autoclave was then cooled to 30 C and vented.The reaction product was washed with 1 liter of water to deactivate any residual catalyst. Analysis qf the organic by VPC gave the following results: Component Area % light ends 3.61 toluene 37.40 isobutylbenzene 51.01 normalbutylbenzene 4.66 heavy ends 3.32 EXAMPLE 3 i) 200 grams of powdered K2CO3 and 90 grams of Na were added to a 1 liter reactor equipped with an agitator and purged with N2. The reactor was heated to 4000 C with a heating mantle; mixing was started when the temperature reached 1200 C. After the temperature reached 4000 C, the reactor was allowed to mix for 30 minutes and then allowed to cool to 60 C. At this point, the catalyst was observed to be a homogeneous silver-colored paste. 15 grams of toluene were added while the contents were allowed to mix.After mixing about 5 minutes, the contents were observed to be a free flowing blue-gray colored powder containing free droplets of liquid NaK. The mixture was transferred to a sample jar using a small spoon.

ii) The catalyst prepared above in i) was added to a 5-gal autoclave under a N2 purged glove bag. The autoclave was sealed up and 2 grams of oleic acid and 8107 grams of toluene were added. Agitation at a tip speed of 24 ft/sec was started and the autoclave was heated to 190"C. 2985 grams of propylene were fed over a 2 hour period at a rate that maintained the autoclave pressure between 375 and 400 psig. The temperature during this feed period was maintained at 190 C. After the propylene had been added, the reaction was allowed to continue at this temperature for an additional 2 hours while the autoclave pressure dropped to 235 psig as remaining propylene reacted. The autoclave was then cooled to 290 C and vented. The reaction product was washed with 1 liter of;water to deactivate any residual catalyst. Analysis of the organic by VPC gave the following results: Component Area % light ends 3.34 toluene 35.50 isobutylbenzene 52.45 normalbutylbenzene 4.86 heavy ends 3.85

Claims

1. A process for producing a catalyst composition which comprises forming a mixture of an alkali metal and an alkali metal carbonate at a temperature sufficient to melt said alkali metal, adding to the mixture an inert liquid dispersant, and separating a free-flowing granular solid catalyst composition.

2. The process according to Claim 1 wherein the quantity of inert liquid dispersant added is from 0.5% to 50% by weight of said mixture.

3. The process according to Claim 2 wherein the quantity of inert liquid dispersant added is from 1% to 10% by weight of said mixture.

4. The process according to Claim 3 wherein the quantity of inert liquid dispersant added is from 3% to 7% by weight of said mixture.

5. The process according to any one of claims 1 to 4 wherein the alkali metal is sodium and the alkali metal carbonate is potassium carbonate.

6. The process according to claim 1 substantially as described in any one of Examples 1 to 3.

7. A catalyst composition produced by the process of any of claims 1 to 6.

8. A process for coupling an alkene with an aromatic hydrocarbon having an active hydrogen on a saturated a-carbon which comprises contacting the said alkene and aromatic hydrocarbon in the presence, as catalyst, of a composition as claimed in claim 7.

9. The process of claim 8 wherein propene is coupled with toluene at 175-2000C in the presence of the catalyst composition.

10. The process of claim 8 substantially as hereinbefore described.

11. Alkylated aromatic hydrocarbons when produced by a process as claimed in any of claims 8 to 10.