Organic compounds -- part of the class 532-570 series – Organic compounds – Oxygen containing
Reexamination Certificate
2002-06-11
2003-12-02
Kumar, Shailendra (Department: 1621)
Organic compounds -- part of the class 532-570 series
Organic compounds
Oxygen containing
C568S840000, C568S852000, C568S913000, C568S914000
Reexamination Certificate
active
06657092
ABSTRACT:
The present invention relates to a process for the preparation of an alcohol composition, more specifically to a process for preparing an alcohol composition having a high linearity.
It is known that oxo-alcohols can be prepared by hydroformylating an olefin into an oxo-aldehyde followed by hydrogenation of this oxo-aldehyde into the oxo-alcohol. Hydroformylation is typically conducted in the presence of a homogeneous catalyst which is based on a source of a transition metal, typically a metal of Group 8 (iron, ruthenium or osmium), 9 (cobalt, rhodium or iridium) or 10 (nickel, palladium or platinum) of the Periodic Table of Elements. In their catalytically active form these metals may be used with carbonyl ligands, but they can also be used as a complex with other ligands, suitably phosphorus-containing ligands. Such catalysts are commonly referred to as phosphine and/or phosphite-modified hydroformylation catalysts.
The secondary reaction, i.e. the hydrogenation of the oxo-aldehyde into the corresponding oxo-alcohol, occurs simultaneously with the actual hydroformylation reaction. Some of the homogeneous hydroformylation catalysts are sufficiently active to hydrogenate the in-situ formed oxo-aldehyde into the desired oxo-alcohol. Sometimes, however, a separate hydrofinishing step is applied in order to improve the quality of the final oxo-alcohol product in terms of its aldehyde content.
Oxo-alcohols may be very useful as plasticizers or detergents. Typically, plasticizer alcohols comprise from 7 to 11 carbon atoms, while detergent alcohols comprise from 12 to 15 carbon atoms. An important element determining the plasticizer and detergent properties of the final oxo-alcohol product is the linearity of the product. Throughout this specification the linearity of an alcohol product is defined as the weight percentage of linear primary mono-alcohols relative to the total amount of alcohols. In general, conventional oxo-processes typically produce alcohols having a linearity of 50 to 60% by weight.
The quality of the olefin feed to the hydroformylation is an important factor in relation to the final properties of the alcohol product. In particular the amount of linear mono-olefins relative to the total amount of olefins present in the feed is an important factor.
In one aspect the present invention aims to provide an optimum quality olefin feed.
International Application No. WO 97/01521 discloses a process for producing oxygenated products, typically aldehydes and alcohols, from an olefin-rich feedstock, which process comprises reacting, in a hydroformylation stage, a Fischer-Tropsch derived olefinic product with carbon monoxide and hydrogen in the presence of a catalytically effective quantity of a hydroformylation catalyst and under hydroformylation reaction conditions, to produce oxygenated products comprising aldehydes and/or alcohols. The olefin-rich feedstock typically contains from 35 to 100% by weight olefins, of which olefins 50 to 100% by weight are linear &agr;-olefins, 0 to 60% by weight mono-methyl branched &agr;-olefins and 0 to 10% by weight linear internal olefins. The minimum olefin content of the feeds used in the working examples is 50% by weight (Examples 9 and 10). The Fischer-Tropsch derived olefinic product is the product obtained by subjecting a synthesis gas comprising carbon monoxide and hydrogen to Fischer-Tropsch reaction conditions in the presence of an iron-based, a cobalt-based or an iron/cobalt-based Fischer-Tropsch catalyst. A clear preference is expressed for iron-based Fischer-Tropsch catalysts, which is also illustrated by the fact that in all working examples describing hydroformylation experiments the hydroformylation feed was based on the product of a Fischer-Tropsch reaction wherein a fused iron catalyst was used.
In the process according to International Application No. WO 97/01521 the feedstock to the hydroformylation reaction stage is an olefin-rich feedstock, which is obtained by reacting carbon monoxide and hydrogen in a Fischer-Tropsch reaction followed by subjecting the Fischer-Tropsch reaction product to distillation treatments. Such distillation treatments are required in order to obtain the carbon fractions with the prescribed minimum olefin content of 35% by weight.
However, the process according to WO-A-97/01521 leaves room for improvement in terms of the combination of alcohol selectivity in the hydroformylation and linearity of the alcohols produced. This is first of all illustrated by the working examples of WO-A-97/01521: in all but one examples where a Fischer-Tropsch feed is used the linearity is at the typical level, while alcohol selectivity is not optimal. In the only example reporting a very high linearity of 84% (Example 5) the alcohol selectivity is only 64%, implying that relatively many by-products are formed. The olefin conversion in this example is also relatively poor: only 68%. Secondly, it was found that when using a fused iron catalyst the resulting olefin stream is characterised by a relatively high content of branched olefins. This is not beneficial for a high linearity of the alcohol product in combination with a high alcohol selectivity. Finally, the high olefin content of the hydroformylation feed, a prerequisite according to WO-A-97/01521, implies that quite a severe distillation treatment of the Fischer-Tropsch reaction product is required.
The present invention aims to overcome these shortcomings. More specifically, the present invention aims to provide a process for producing oxo-alcohols by the hydroformylation of Fischer-Tropsch product streams, which results in highly linear alcohols in combination with a high alcohol selectivity in the hydroformylation stage, thus limiting the amount of by-products formed. The expression “selectivity” as used throughout this specification refers to the percentage of alcohol products formed relative to the amount of total products formed from the converted olefins:
selectivity
=
amount alcohols formed
×
100
%
total amount reaction products
Furthermore, in the process of the present invention very high olefin conversion rates should be attainable, while it should also not be required to use hydroformylation feeds comprising 35% by weight or more of olefins.
It was surprisingly found that by selecting specific types of catalysts in both the Fischer-Tropsch and hydroformylation stage highly linear alcohol products could be obtained at very high alcohol selectivity and conversion rates.
The present invention provides a process for the preparation of an alcohol composition comprising one or more primary mono-alcohols, at least 60% by weight of which consists of linear primary mono-alcohols containing at least 7 carbon atoms. The process contains the steps of:
(a) reacting carbon monoxide with hydrogen under Fischer-Tropsch reaction conditions in the presence of a Fischer-Tropsch catalyst comprising cobalt;
(b) separating from the product of step (a) at least one hydrocarbon fraction comprising between 10 and 50% by weight of olefins containing 6 or more carbon atoms;
(c) contacting one or more, of the hydrocarbon fractions obtained in step (b) with carbon monoxide and hydrogen under hydroformylation conditions in the presence of a hydroformylation catalyst based on a source of cobalt and one or more alkyl phosphines; and
(d) recovering the alcohol composition.
Accordingly, a process for the preparation of an alcohol composition is provided, comprising at least one primary mono-alcohol, at least 60% by weight of which consists of linear primary mono-alcohols containing at least 7 carbon atoms, said process comprising the steps of:
(a) reacting carbon monoxide with hydrogen under Fischer-Tropsch reaction conditions in the presence of a Fischer-Tropsch catalyst comprising cobalt;
(b) separating from the product of step (a) at least one hydrocarbon fraction comprising between 10 and 50% by weight of olefins containing 6 or more carbon atoms;
(c) contacting at least one of the hydrocarbon fractions obtained in step (b) with carbon monoxide and hydrogen under hy
Dirkzwager Hendrik
Fenouil Laurent Alain
Geijsel Joannes Ignatius
Hoek Arend
Van Der Steen Frederik Hendrik
Kumar Shailendra
Price Eluis O.
Shell Oil Company
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