Heavy Alkylbenzene Transalkylation Operating Cost Reduction (UOP LLC)

CATEGORY: BENZENE
PATENT
Heavy Alkylbenzene Transalkylation Operating Cost Reduction (UOP LLC)
United States Patent Application 20130096357
Inventors:
Sohn, Stephen W. (Arlington Heights, IL, US)
Riley, Mark G. (Hinsdale, IL, US)
Application Number:
13/690760
Publication Date:
04/18/2013
Assignee:
UOP LLC (Des Plaines, IL, US)
Abstract:
A process for increasing the production of monoalkylbenzenes is presented. The process includes utilizing a transalkylation process to convert dialkylbenzenes to monoalkylbenzenes. The transalkylation process recycles a portion of the effluent stream from the transalkylation reactor back to the feed of the transalkylation reactor. The recycled dialkylbenzenes and a portion of the recycled benzene are converted to monoalkylbenzenes.
CROSS-REFERENCE TO RELATED APPLICATION
This application is a Division of prior copending application Ser. No. 12/917,851 which was filed on Nov. 2, 2010, the contents of which are incorporated herein by reference thereto.
FIELD OF THE INVENTION
The present invention relates to the alkylation of benzene. In particular, the present invention relates to the conversion of dialkylbenzenes to monoalkylbenzenes.
BACKGROUND OF THE INVENTION
The alkylation of benzene with olefins produces a variety of alkylbenzene compounds that have various commercial uses. Examples include the alkylation of benzene with olefins having 8 to 16 carbons for the production intermediate compounds in the manufacture of detergents. The alkylbenzenes are sometimes referred to as phenylalkanes, and are produces as a commodity in amounts between 50,000 and 200,000 metric tonnes per year, at a large scale facility. The alkylation process comprises reacting benzene with an olefin in the presence of a catalyst at elevated temperatures. The catalysts can be homogeneous or heterogeneous catalysts such as hydrogen fluoride, aluminum chloride, silica alumina, or zeolitic catalysts.
The desired alkylated compounds are monoalkylated aromatic compounds. Two common reactions for producing monoalkylated aromatic compounds are alkylation of aromatic compounds such as benzene, and transalkylation of polyalkylated aromatic compounds. Monoalkylated aromatic compounds include linear alkylbenzenes (LAB), which are used to form linear alkylbenzene sulfonates (LABS), a common compound used in detergents, and which are manufactured from linear alkylbenzenes. One aspect of benzene alkylation has been the use of high benzene to olefin ratios for the production of alkylbenzene production. The transalkylation process reacts the polyalkylated aromatic compound with benzene to form a monoalkylated product. Both the alkylation and transalkylation processes involve the use of benzene in a relatively high molar ratio with respect the olefin or polyalkylated aromatic compound.
Currently, monoalkylated benzenes are desired, and polyalkylated benzenes are by-products that need to be removed or need to be recycled to try and produce more monoalkylated benzenes. The method of reducing the amount of polyalkylated benzenes is to increase the benzene to olefin ratio. The other method of reducing polyalkylated benzenes is to pass the polyalkylbenzenes through a transalkylation reactor. However, the industry is striving to reduce the benzene to olefin ratio, and the usual method is to use many small beds with decreasing ratios as the benzene and olefins pass through successive beds. The cost of producing a pure benzene stream is expensive, and the cost of separating and recycling benzene is expensive and energy intensive.
Methods of improving the recovery and usage of benzene can result in substantial savings in energy and expense.
SUMMARY OF THE INVENTION
The production of linear alkylbenzenes requires a substantial excess of benzene for the reaction to proceed, while limiting other undesirable side reactions. The excess benzene is expensive, and is balanced against the amount of by-products generated in the alkylation process. Reducing the amount of benzene increases the amount of dialkylbenzenes, or heavies, produced. The present invention provides a process for increasing the amount of alkylbenzenes, or monoalkylbenzenes. The process continuously supplies benzene and dialkylbenzenes to a transalkylation reactor. The reactor is operated under reaction conditions, and the benzene and dialkylbenzene react in the presence of a catalyst to generate an effluent stream comprising benzene, dialkylbenzene and monoalkylbenzene. A portion of the effluent stream is taken as a recycle stream, without separation, and passed back to the transalkylation reactor.
In one embodiment, the recycle stream comprises more than 50% of the effluent stream. Additional objects, embodiments and details of this invention can be obtained from the following detailed description of the invention.
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