Catalyst – solid sorbent – or support therefor: product or process – Catalyst or precursor therefor – Organic compound containing
Reexamination Certificate
2001-04-10
2004-11-30
Bell, Mark L. (Department: 1755)
Catalyst, solid sorbent, or support therefor: product or process
Catalyst or precursor therefor
Organic compound containing
C502S169000, C502S170000, C502S171000, C526S135000, C526S136000, C526S172000
Reexamination Certificate
active
06825148
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a certain nickel-containing catalyst and a process for the oligomerization of ethylene to a mixture of olefinic products having high linearity using such catalyst.
BACKGROUND OF THE INVENTION
The production of a mixture of olefinic products which are substantially alpha-olefins and which have a high degree of linearity are known. Such olefins comprise for example, those of the C
4
-C
10
range, useful as comonomers for LLDPE or as synthetic lubricants; those of the C
12
-C
20
range, useful as detergents; and higher olefins. The lower molecular weight olefins can be converted to sulfonates or alcohols by known commercial processes. The C
12
-C
20
olefins find use in the detergent-products area. Lower molecular weight alcohols can be esterified with polyhydric acids, e.g., phthalic acid to form plasticizers for polyvinylchloride.
U.S. Pat. No. 3,676,523, herein incorporated by reference, discloses the use of an ethylene oligomerization catalyst in the production of such olefinic products which comprises (1) a divalent nickel salt, (2) a boron hydride reducing agent, and (3) an o-dihydrocarbylphosphinobenzoic acid or alkali metal salt thereof.
One drawback to the use of this catalyst, however, is expense. There exists a need for a lower cost catalyst in the production of such olefinic products.
SUMMARY OF THE INVENTION
This invention relates to a process for the oligomerization of ethylene to a mixture of olefinic products having high linearity by using a catalyst comprising a simple divalent nickel salt; a boron hydride reducing agent; a water soluble base; a ligand selected from the group consisting of o-dihydrocarbyl-phosphinobenzoic acids and alkali metal salts thereof; and a trivalent (three-coordinate) phosphite.
DETAILED DESCRIPTION OF THE INVENTION
It has been found that the use of a certain ligand provides for a cost effective catalyst useful in the production of olefinic products.
Nickel Salts:
In general, any simple divalent nickel salt can be employed for preparing the catalyst composition of the invention provided the nickel salt is sufficiently soluble in the reaction medium. By the term “simple divalent” nickel salt is meant a nickel atom having a formal valence of +2 and bonded through ionic or electrovalent linkages to two singly charged anionic groups (e.g., halides) or to one doubly charged anionic group (e.g., carbonate) and not complexed with or coordinated to any other additional molecular or ionic species. Simple divalent nickel salts therefore do not encompass complex divalent nickel salts which are bonded to one or two anionic groups and additionally complexed or coordinated to neutral chelating ligands or groups such as carbon monoxide and phosphines. However, simple divalent nickel salts are meant to include nickel salts containing water of crystallization in addition to one or two anionic groups.
In most instances, a simple divalent nickel salt with a solubility in the reaction diluent or solvent employed for catalyst preparation of at least 0.001 mole per liter (0.001M) is satisfactory for use as the nickel catalyst precursor. A solubility in the reaction diluent or solvent of at least 0.01 mole per liter (0.01M) is preferred, and a solubility of at least 0.05 mole per liter (0.05M) is most preferred. Reaction diluents and solvents suitably employed for catalyst preparation are the polar organic solvents suitably employed for the oligomerization process which solvents are defined below.
Suitable simple divalent nickel salts include inorganic as well as organic divalent nickel salts. Illustrative inorganic nickel salts are nickel halides such as nickel chloride, nickel bromide and nickel iodide, nickel carbonate, nickel chlorate, nickel ferrocyanide, and nickel nitrate. Illustrative organic divalent nickel salts are nickel salts of carboxylic acids such as nickel alkanoates of up to ten carbon atoms, preferably of up to six carbon atoms, e.g. nickel formate, nickel acetate, nickel propionate, nickel hexanoate and the like; nickel oxalate; nickel benzoate and nickel naphthenate. Other suitable organic salts include nickel benzenesulfonate, nickel citrate, nickel dimethylglyoxime and nickel acetylacetonate.
Nickel halides, especially nickel chloride, and nickel alkanoates, in part because of their availability at low cost and solubility in polar organic solvents are preferred nickel salts.
Dihydrocarbylphosphinobenzoic Acid:
The o-dihydro-carbylphosphino-benzoate ligands employed in the preparation of the catalyst composition of the invention generally have from eight to 30 carbon atoms, but preferably from 14 to 20 carbon atoms, and are preferably represented by the formula (I):
wherein R is a monovalent hydrocarbyl group and M is hydrogen or an alkali metal. The M group is preferably hydrogen, sodium or potassium. Illustrative examples of R groups are hydrocarbon alkyl groups such as methyl, ethyl, isobutyl, lauryl, stearyl, cyclohexyl, and cyclopentyl; hydrocarbon alkenyl R groups having aromatic substituents such as benzyl, phenylcyclohexyl, and phenylbutenyl. Aromatic R groups such as phenyl, tolyl, xylyl and p-ethylphenyl. Preferred R groups are aromatic groups of six to ten carbon atoms, especially phenyl, and cycloalkyl of five to ten carbon atoms, especially cyclohexyl.
Illustrative examples of o-dihydrocarbyl-phosphinobenzoate ligands of formula (I) are o-diphenylphosphinobenzoic acid, o-(methylphenyl-phosphino)benzoic acid, o-(ethyltolylphosphino)benzoic acid, o-dicyclohexylphosphinobenzoic acid, o-(cyclohexyl-phenylphosphino)benzoic acid, o-dipentylphosphinobenzoic acid and the alkali metal salts thereof.
Preferred benzoate ligands of formula (I) are those wherein the R groups are aromatic or cycloalkyl of six to ten carbon atoms, particularly diarylphosphinobenzoic acids, arylcycloalkylphosphinobenzoic acids and the alkali metal salts thereof. Such aryl- and cycloalkyl-substituted phosphino-benzoate ligands are preferred largely because catalyst compositions prepared therefrom catalyze the oligomerization of ethylene to a product mixture containing a high proportion of oligomers in the useful C
12
-C
20
carbon range.
Although the o-dihydrocarbylphosphinobenzoate ligands are suitably employed as the free acid, better results are occasionally obtained with the alkali metal salts of the o-dihydrocarbylbenzoic acid. The alkali metal salts are suitably preformed from the benzoic acid by treatment with an alkali metal hydroxide or oxide solution prior to catalyst preparation or, alternatively, the carboxylic acid salt is generated in situ by the reaction of equimolar amounts of the carboxylic acid and an alkali metal hydroxide during catalyst preparation.
When preparing the catalyst, the molar ratio of nickel salt to benzoate ligand (free acid or salt thereof) is at least 1:1, i.e., at least one mole nickel salt is provided for each mole of benzoate ligand. Suitable molar ratios of nickel salt to benzoic acid ligand (or salt thereof) range from about 1:1 to about 10:1, although molar ratios of about 1:1 to about 3:1 are preferred.
Boron Hydride Reducing Agent:
In general, any boron hydride salt reducing agent of reasonable purity is suitable for use in the process of the invention. Specific examples include alkali metal borohydrides such as sodium borohydrides, potassium borohydride and lithium borohydride; alkali metal alkoxyborohydrides wherein each alkoxy has one to four carbon atoms, such as sodium trimethoxyborohydride and potassium tripropoxyborohydride and tetraalkylammonium borohydrides wherein each alkyl has one to four carbon atoms, such as tetraethylammonium borohydride. Largely because of commercial availability, alkali metal borohydrides are preferred and especially preferred is sodium borohydride.
When preparing the catalyst, the molar ratio of boron hydride salt to nickel salt is at least about 0.2:1. There does not appear to be a definite upper limit on the boron hydride
ickel ratio, but for economic reasons it is especially preferred that the molar ratio be not greater th
Brown David Stephen
Robertson Richard Edward
Bell Mark L.
Pasterczyk J.
Shell Oil Company
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