Organic compounds -- part of the class 532-570 series – Organic compounds – Oxygen containing
Reexamination Certificate
2000-05-08
2003-05-20
Barts, Samuel (Department: 1621)
Organic compounds -- part of the class 532-570 series
Organic compounds
Oxygen containing
Reexamination Certificate
active
06566565
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to a process for preparing olefins used in forming surfactants. Specifically, the invention relates to the formation of selectively branched olefins which are converted to biodegradable, selectively branched alcohols.
BACKGROUND OF THE INVENTION
Alcohols of long chain olefins having about 6 to 36 carbon atoms have considerable commercial importance in a variety of applications, including detergents, soaps, surfactants, and freeze point depressants in lubricating oils. These alcohols are produced by a number of commercial processes, such as by oxo or hydroformylation of long chain olefins. Typical commercially available long chain alcohols are the NEODOL® alcohols available from Shell Chemical Company, the EXXAL® alcohols available from Exxon Chemical Company, and the LIAL® alcohols available from Enichem.
In the manufacture of the NEODOL® alcohols, a predominantly linear olefin feed is subjected to hydroformylation by reacting carbon monoxide and hydrogen onto the olefin in the presence of an oxo catalyst to form an alcohol. Over 80% of the alcohol molecules in the resulting alcohol are linear primary alcohols. Of the branched primary alcohols in the composition, most, if not all of the branching is on the C
2
carbon atom relative to the hydroxyl bearing carbon atom. These alcohols subsequently can be converted to anionic or nonionic detergents or general surfactants by sulfonation or ethoxylation of the alcohol, or by conversion of the alcohol to an alcohol-ethoxysulfate.
The NEODOL® alcohols are commercially successful intermediates to the production of detergents. One reason for this success undoubtedly is that the NEODOL® alcohols are economically produced with high yields of linear alcohols. The sulfonates of linear alcohols are more biodegradable than the sulfonates of highly branched long chain alcohols. Since detergents and soaps used by consumers for washing ultimately are released into the environment, the need for surfactants or detergents with acceptable biodegradability is well recognized.
The highly linear NEODOL® alcohols have the advantage of a high level of biodegradability; however, the high degree of linearity of these alcohols also increases their hydrophobicity, thereby decreasing their cold water solubility/detergency. Thus, there is a need for an alcohol composition having both increased biodegradability and increased solubility.
Alcohols that have been found to meet both the biodegradability and the solubility government standards are branched primary alcohols and their sulfate derivatives: having about 8 to about 36 carbon atoms; having an average number of branches per molecular chain of at least 0.7; having less than 0.5 atom % of quaternary carbon atoms; and, having at least methyl and ethyl branching. These alcohols, as well as a method for preparing them, are described in U.S. Pat. No. 5,849,960, incorporated herein by reference. The method basically involves contacting a feed comprising linear olefins having 7 to 35 carbon atoms with a skeletal isomerization catalyst, and converting the resulting skeletally isomerized olefin to a saturated branched primary alcohol, preferably by hydroformylation.
Methods capable of producing similar compounds with greater operating efficiency are always desirable.
SUMMARY OF THE INVENTION
The present invention provides a process for making a selectively branched alcohol composition. The process comprises contacting an oligomerization catalyst under oligomerization conditions with an olefin feed comprising linear olefins having at least 3 carbon atoms. The oligomerization catalyst is effective to oligomerize the linear olefins to produce selectively branched olefins having up to about 36 carbon atoms. One or both of the olefins selected from the group consisting of the selectively branched olefins and the olefin feed comprise a concentration of an impurity selected from the group consisting of dienes and phosphorous containing compounds. The concentration of the impurity is reduced in a material selected from the group consisting of the olefin feed and the selectively branched olefins. The selectively branched olefins are converted to the selectively branched alcohol composition.
DETAILED DESCRIPTION OF THE INVENTION
The present invention relates to a process for oligomerizing lower olefins having at least 3 carbon atoms, preferably from about 3 to about 18 carbon atoms, most preferably from about 6 to about 10 carbon atoms, into selectively branched olefins having from about 6 to about 36 carbon atoms, preferably from about 11 to about 20 carbon atoms, and most preferably from about 14 to about 18 carbon atoms. The selectively branched olefins are hydroformylated and converted to selectively branched alcohols. An oligomerization catalyst is used to oligomerize the olefins, thereby increasing carbon number and selective branching. The selectively branched alcohols preferably are used to prepare biodegradable surfactants for use in detergent formulations.
The process of oligomerization to form selectively branched olefins is defined to mean subjecting olefins having fewer carbon atoms to conditions that form longer chains having more carbon atoms.
The resulting selectively branched olefins typically contain at least some dienes, which tend to poison and reduce the overall effectiveness of the hydroformylation catalyst. In order to prevent this poisoning, the dienes present in the selectively branched olefins preferably are removed prior to hydroformylation. The selectively branched olefins are hydroformylated to form a saturated alcohol which may be sulfonated or ethoxylated. The dienes also be may removed from the lower olefins prior to oligomerization, in order to prevent potential poisoning of the oligomerization catalyst.
Depending upon the catalyst used to make the lower olefins, phosphorus may be present in the lower olefin feed. Basic phosphorus compounds tend to reduce the effectiveness of the oligomerization catalyst and it is therefore desirable to remove the phosphorus from the lower olefin feed prior to oligomerization.
Olefin Feed
Suitable olefins used in the olefin feed for oligomerization are “lower olefins” defined herein as mono-olefins having at least 3 carbon atoms, preferably having from about 3 to about 18 carbon atoms, and most preferably having from about 6 to about 10 carbon atoms. In general, the olefins in the lower olefin feed are predominately linear. While the lower olefin feed may contain some selectively branched olefins, the lower olefin feed preferably contains greater than about 50 wt. %, more preferably greater than about 70 wt. %, and most preferably greater than about 80 wt. % or more of linear lower olefin molecules.
Lower olefins are available from a wide variety of sources. The lower olefin feed may not consist of 100% olefins within the specified carbon number range. The lower olefin feed may contain olefins of other carbon number or carbon structure, diolefins, paraffins, and other impurities. The location of the double bond is not limited. The lower olefin feed composition may comprise alpha-olefins, internal olefins, or a mixture thereof.
Commercial olefin products manufactured by ethylene oligomerization are marketed in the United States by Shell Chemical Company under the trademark NEODENE and by Ethyl Corporation as ALPHA-OLEFINS. Specific procedures for preparing suitable lower olefin feeds from ethylene are described in U.S. Pat. Nos. 3,676,523, 3,686,351, 3,737,475, 3,825,615 and 4,020,121, the teachings of which are incorporated herein by reference.
Oligomerization Catalyst, Conditions and Product
The catalyst used to treat the lower linear olefins is effective to oligomerize a lower olefin composition into an olefin composition having an average number of branches per molecule chain of at least 0.7. A preferred catalyst contains a medium pore zeolite having at least one channel with a crystallographic free channel diameter from about 4.2 Å to about 7 Å, measured at room temperature, with essentially no cha
Murray Brendan Dermot
Singleton David Michael
Barts Samuel
Price Elvis O.
Shell Oil Company
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