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AssigneeSasol North America Inc.
InventorsJ. Barry Winder, Donald L. Wharry, John R. Schell, Mary J. Brown, Joy L. Murray, Richard C. Howe, Wayne L. Sorensen, Daniel P. Szura
Estimating the term…
A unified process for reactive distillation under pressure for the alkylation of light aromatic hydrocarbons such as benzene and cumene with straight chain C6-C18 olefins using a solid acid alkylation catalyst supported in the reflux zone of the distillation column. The process is continuous, using a reactive distillation configuration such that at least a portion of the olefin is injected below the benzene rectification zone at the top of the column. The aromatic hydrocarbon is injected continuously at a low rate above the rectification zone at the base of the column and above the reboiler. The alkylation reaction takes place primarily in the liquid phase on the solid acid catalyst and is characterized in that the molar ratio of aromatic hydrocarbon to olefin in the liquid phase may be adjusted. The molar ratio is adjustable up to about 100/1, through adjustment of the internal column operating pressure, the benzene reflux rate, the amount of benzene removed from the reflux condenser to storage or from the reboiler with the distillation column operated at or near total aromatic hydrocarbon reflux. The unexpectedly high liquid phase aromatic hydrocarbon to olefin molar ratios achieved in the reactive distillation column increases the selectivity to mono-alkylated aromatics and helps stabilize catalyst lifetime.
A process for the continuous preparation of mono-alkylated aromatic compounds in a reactive distillation column including a reactive zone, a first rectification zone at the top of the distillation column and a second rectification zone below said reactive zone and further containing a solid acid alkylation catalyst supported in the reactive zone, said process comprising:
A process for the continuous preparation of alkylated aromatic compounds comprising:
Dependencies are inferred from the claim text.
From the US filing history. Foreign family members aren’t listed.
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Addition to a carbon atom of a six-membered aromatic ring: catalytic processes
Technologies relating to chemical industry: process efficiency
Acyclic or carbocyclic compounds
Low-carbon manufacturing
Term ended 5 Mar 2022 (estimated)
This invention relates to an alkylation process. More particularly, this invention relates to the alkylation of aromatic hydrocarbons with olefins in a continuous, pressurized, reactive distillation process employing a solid alkylation catalyst system.
Linear alkylated aromatic compounds have many uses of significant commercial value. For example, alkylated light aromatic compounds, such as benzene and cumene, have value as gasoline octane enhancers. Aromatic compounds alkylated with long chain (that is, having greater than about 10 carbon atoms) linear olefins are commonly sulfonated to produce surfactants suitable for use in detergent manufacture.
The chemical reactions involving alkylation of aromatics with olefins have been studied for a long time. For example, U.S. Pat. No. 2,860,173 discloses the use of a solid phosphoric acid as a catalyst for the alkylation of benzene with propylene to produce cumene. More recently, the use of Friedel Crafts catalysts, especially aluminum chloride and certain natural zeolites and synthetic commercial sieves, as alkylation catalysts, has been taught.
FIG. 1 provides a schematic representation of the continuous reactive distillation system of the invention as two separate and connected columns performing as a single system.
By “light aromatic” or “aromatic”, we mean organic aromatic compounds having one or more rings and from 6 to about 30 carbon atoms, preferably 6-20 carbon atoms, that boil at or below about 250° C. under pressure conditions typical in a commercial reactor-type distillation column. The preferred members of this group are benzene, toluene, xylene, styrene, phenol and cumene, with benzene being especially preferred.
The preferred olefins useful in this invention include those straight-chain and/or mono methyl branched, mono-unsaturated olefins having from 6 to about 30 carbon atoms, preferably from about 8 to about 20 carbon atoms and, more preferably, from 10 to 14 carbon atoms. The preferred olefin feed is a C6-C18 paraffin, C6-C18 olefin, mixture that is derived from a commercial paraffin dehydrogenation process.
The conditions of the subject reactive distillation process require that the internal pressure in the reactive zone be maintained substantially constant and above about 1 atmosphere, preferably between about 20 and about 200 psig. In addition, the combination of aromatic hydrocarbon, unreacted olefin, alkylated aromatics and other by-products, in the reboiler, is maintained at or near total reflux, such that the temperature in the reboiler stays below the thermal degradation temperature of the alkylated product, which is about 265° C., and the molar ratio of the aromatic hydrocarbon to the olefin in the liquid phase is between about 20/1 to about 100/1, preferably between about 30/1 to about 80/1. Under these conditions, the reboiler liquid should preferably be maintained to contain at least 2% by weight aromatic hydrocarbon and the introduction of the aromatic hydrocarbon into the distillation column maintained at a feed rate which is between about ⅙ to about ½ the feed rate of the olefin into the distillation column.