Chemistry of hydrocarbon compounds – Plural serial diverse syntheses – To produce aromatic
Reexamination Certificate
2002-12-20
2003-12-30
Dang, Thuan D. (Department: 1700)
Chemistry of hydrocarbon compounds
Plural serial diverse syntheses
To produce aromatic
C585S319000, C585S448000, C585S455000, C585S660000, C585S661000, C585S740000, C585S750000, C585S751000
Reexamination Certificate
active
06670516
ABSTRACT:
FIELD OF THE INVENTION
The invention relates generally to the alkylation of phenyl compounds with olefins using solid catalyst, and more specifically to a process for selectively producing particular phenyl-alkanes using a solid alkylation catalyst.
BACKGROUND OF THE INVENTION
More than about thirty years ago, many household laundry detergents were made of branched alkylbenzene sulfonates (BABS). BABS are manufactured from a type of alkylbenzenes called branched alkylbenzenes (BAB). Alkylbenzenes (phenyl-alkanes), refer to a general category of compounds having an aliphatic alkyl group bound to a phenyl group and having the general formula of (m
i
-alkyl
i
)
i
-n-phenyl-alkane. The aliphatic alkyl group consists of an aliphatic alkyl chain, which is referred to by “alkane” in the (m
l
-alkyl
i
)
i
-n-phenyl-alkane formula. Of the chains of the aliphatic alkyl group, the aliphatic alkyl chain is the longest straight chain that has a carbon bound to the phenyl group. The aliphatic alkyl group may also consist of one or more alkyl group branches, each of which is attached to the aliphatic alkyl chain and is designated by a corresponding “(m
i
-alkyl
i
)
i
” in the (m
i
-alkyl
i
)
i
-n-phenyl-alkane formula. If it is possible to select two or more chains of equal lengths as the aliphatic alkyl chain, the choice goes to the chain carrying the greatest number of alkyl group branches. The subscript counter “i” thus has a value of from 1 to the number of alkyl group branches, and for each value of i, the corresponding alkyl group branch is attached to carbon number m
i
of the aliphatic alkyl chain. The phenyl group is attached to the aliphatic alkyl group, specifically to carbon number n of the aliphatic alkyl chain. The aliphatic alkylation chain is numbered from one end to the other, the direction being chosen so as to give the lowest number possible to the position of the phenyl group.
The characteristics of BAB are described in U.S. Pat. No. 6,187,981 B1, which is hereby incorporated herein by reference, and therefore it is not necessary to describe them in detail here. Briefly, BAB has a relatively large number of primary carbon atoms per aliphatic alkyl group, the phenyl group in BAB can be attached to any non-primary carbon atom of the aliphatic alkyl chain, and there is a relatively high probability that one of the carbons of the aliphatic alkyl group of BAB is a quaternary carbon.
It is helpful for what follows to briefly describe phenyl-alkanes having quaternary carbon atoms. When a carbon atom on the alkyl side chain not only is attached to two other carbons on the alkyl side chain and to a carbon atom of an alkyl group branch but also is attached to a carbon atom of the phenyl group, the resulting alkyl-phenyl-alkane is referred to as a “quaternary alkyl-phenyl-alkane” or simply a “quat.” Thus, quats comprise alkyl-phenyl-alkanes having the general formula m-alkyl-m-phenyl-alkane. If the quaternary carbon is the second carbon atom numbered from an end of the alkyl side chain, the resulting 2-alkyl-2-phenyl-alkane is referred to as an “end quat.” If the quaternary carbon is any other carbon atom of the alkyl side chain, then the resulting alkyl-phenyl-alkane is referred to as an “internal quat.”
About thirty years ago it became apparent that household laundry detergents made of BABS were gradually polluting rivers and lakes. Investigation into the problem led to the recognition that BABS were slow to biodegrade. Solution of the problem led to the manufacture of detergents made of linear alkylbenzene sulfonates (LABS), which were found to biodegrade more rapidly than BABS. Today, detergents made of LABS are manufactured world-wide. LABS are manufactured from another type of alkylbenzenes called linear alkylbenzenes (LAB). LAB is also described in U.S. Pat. No. 6,187,981 B1. LAB has a linear aliphatic alkyl group with two primary carbon atoms, and the phenyl group in LAB is usually attached to any secondary carbon atom of the linear aliphatic alkyl group.
Over the last few years, other research has identified certain modified alkylbenzene sulfonates, which are referred to herein as MABS. MABS are different in composition from BABS and LABS. MABS also differ from these other alkylbenzene sulfonates by having improved laundry cleaning performance, hard surface cleaning performance, and excellent efficiency in hard water, while also having biodegradability comparable to that of LABS. MABS can be produced by sulfonating modified alkylbenzenes (MAB). MAB is a phenyl-alkane comprising a lightly branched aliphatic alkyl group and a phenyl group and has the general formula (m
i
-alkyl
i
)
i
-n-phenyl-alkane. MAB usually has two, three, or four primary carbons, contains a high proportion of 2-phenyl-alkanes, and has a relatively low proportion of internal quats. MAB is described in detail in U.S. Pat. No. 6,187,981 B1, which discloses an MAB alkylation process. For other alkylation processes and adsorptive separation processes that produce uniquely lightly branched or delinearized alkylbenzenes, see PCT International Publication Nos. WO 99/05082, WO 99/05084, 99/05241, WO 99/05243, and W099/07656, which are hereby incorporated herein by reference.
Because of the advantages of MABS over other alkylbenzene sulfonates, catalysts and processes are sought that selectively produce MAB with a desired selectivity to 2-phenyl-alkanes and to internal quaternary phenyl-alkanes.
SUMMARY OF THE INVENTION
A process for the production of phenyl-alkanes, in particular modified alkylbenzenes (MAB), by the steps of paraffin dehydrogenation, olefin isomerization, and alkylation of a phenyl compound, in which paraffins in the alkylation effluent are recycled to the dehydrogenation step, is disclosed. The paraffins that are recycled may be linear or nonlinear paraffins, including lightly branched paraffins. Because the recycled paraffins can be converted into lightly branched olefins, this process efficiently recovers paraffins in the alkylation effluent and uses them to produce valuable phenyl-alkane products. This process thus increases the yield of valuable products for a given amount of paraffinic feedstock charged to the process while avoiding the difficulty of separating the paraffins from the monoolefins after the paraffin dehydrogenation step and prior to the alkylation step.
This process, when used for detergent alkylation, produces detergents that meet the increasingly stringent requirements of 2-phenyl-alkanes selectivity and internal quaternary phenyl-alkane selectivity for the production of modified alkylbenzenes (MAB). Thus, the MAB in turn can be sulfonated to produce modified linear alkylbenzene sulfonates (MABS), which have improved cleaning effectiveness in hard and/or cold water while also having biodegradability comparable to that of linear alkylbenzene sulfonates.
It is believed that the MAB and MABS produced by the processes disclosed herein are not necessarily the products that would be produced by the prior art processes that do not recycle paraffins. Without being bound to any particular theory, it is believed that in the dehydrogenation zone the extent of conversion of branched paraffins can be greater than that of normal (linear) paraffins, and/or that the extent of conversion of heavier paraffins can be greater than that of lighter paraffins. In this case, since the extent of conversion of paraffins is limited by equilibrium, the dehydrogenation zone effluent can contain more linear and/or lighter paraffins. Thus, the concentration of linear paraffins and/or lighter paraffins in the recycle paraffin stream could increase. This, in turn, could increase the concentration and ultimately the conversion of linear and/or lighter paraffins in the dehydrogenation zone until the rate of removal from the process of linear and/or lighter paraffins via dehydrogenation and subsequent alkylation equals the rate of introduction into the dehydrogenation zone of those paraffins from the paraffin feedstock and the recycle paraffin stream. Accordingly, for a given extent of olefin conversion in
Fritsch Thomas R.
Galperin Leonid B.
Lawson R. Joe
Marinangeli Richard E.
Dang Thuan D.
Moore Michael A.
Tolomei John G.
UOP LLC
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