Separation Of Iso-Olefins From Paraffins In The C19 To C22 Range (United States Patent Application 20150148577 - UOP)

Separation Of Iso-Olefins From Paraffins In The C19 To C22 Range (United States Patent Application 20150148577 - UOP)
May 28, 2015
Abstract
A process is presented for the separation of iso-olefins from a hydrocarbon mixture comprising paraffins and olefins. The process includes an adsorption separation system, wherein the adsorbent is selected according to the properties of the material that is desired to be adsorbed. The process also includes a selection of a desorbent, which can comprise a mixture, to provide for an enhanced recovery of the adsorbed material and a separation of the iso-olefins from paraffins.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to the field of benzene alkylation. In particular, this invention relates to the production of the precursor olefinic materials used in the production of surfactants.
BACKGROUND
[0002] Alkylation of benzene produces alkylbenzenes that may find various commercial uses, e.g., alkylbenzenes can be sulfonated to produce surfactants, for use in detergents. In the alkylation process, benzene is reacted with an olefin the desired length to produce the sought alkylbenzene. The alkylation conditions comprise the presence of homogeneous or heterogeneous alkylation catalyst such as aluminum chloride, hydrogen fluoride, or zeolitic catalysts and elevated temperature.
[0003] Various processes have been proposed to alkylate benzene. One commercial process involves the use of hydrogen fluoride as the alkylation catalyst. The use and handling of hydrogen fluoride does provide operational concerns due to its toxicity, corrosiveness and waste disposal needs. Solid catalytic processes have been developed that obviate the need to use hydrogen fluoride. Improvements in these solid catalytic processes are sought to further enhance their attractiveness through reducing energy costs and improving selectivity of conversion while still providing an alkylbenzene of a quality acceptable for downstream use such as sulfonation to make surfactants.
[0004] Alkylbenzenes, to be desirable for making sulfonated surfactants must be capable of providing a sulfonated product of suitable clarity, biodegradability and efficacy. With respect to efficacy, alkylbenzenes having higher 2-phenyl contents are desired as they tend, when sulfonated, to provide surfactants having better solubility and detergency. Thus, alkylbenzenes having a 2-phenyl isomer content in the range from about 30 to about 40 percent are particularly desired.
[0005] The production of alkylbenzenes requires the production of olefins for alkylation of the benzene. The olefins for detergents are preferably linear alpha olefins, which produce alkylbenzenes having favorable biodegradability properties. The recovery of olefins from a hydrocarbon stream affects the ability to economically produce the alkylbenzenes. Improvements in the production and recovery of olefins can improve the economics of alkylbenzene production.
SUMMARY
[0006] The present invention is a process that utilizes the properties of the adsorbent and desorbent to improve the separation of components from a mixture.
[0007] A first embodiment of the invention is a process for separating olefins from a hydrocarbon stream comprising passing a hydrocarbon stream comprising C19 to C22 olefins and paraffins to an adsorption separation system, thereby creating an extract stream comprising iso-olefins and normal olefins, and a raffinate stream having a reduced iso-olefin and normal olefin content; wherein the adsorbent comprises a alkali substituted zeolite, and wherein the adsorption separation system uses a desorbent that comprises a naphthene or naphthene mixture. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the first embodiment in this paragraph wherein the alkali substituted zeolite is sodium substituted X zeolite. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the first embodiment in this paragraph wherein the desorbent comprises a naphthene in the C5 to C10 range. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the first embodiment in this paragraph wherein the desorbent comprises a naphthene selected from the group cyclohexane, methylcyclohexane, methylcyclopentane, cyclopentane and mixtures thereof An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the first embodiment in this paragraph wherein the iso-olefins comprise mono-methyl, mono-ethyl and mono-propyl olefins. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the first embodiment in this paragraph further comprising passing the extract stream to a first separation unit to generate an extract process stream and an extract desorbent stream. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the first embodiment in this paragraph further comprising passing the extract desorbent stream back to the adsorption separation column. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the first embodiment in this paragraph further comprising passing the raffinate stream to a second separation unit to generate a raffinate process stream and a raffinate desorbent stream. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the first embodiment in this paragraph further comprising passing the raffinate desorbent stream back to the adsorption separation column. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the first embodiment in this paragraph wherein the hydrocarbon stream is generated from gas to liquids technology to generate a feedstream comprising paraffins. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the first embodiment in this paragraph further comprising passing the feedstream comprising paraffins to a paraffin to olefin conversion zone to generate the hydrocarbon stream comprising C19 to C22 olefins and paraffins.
[0008] A second embodiment of the invention is a process for the production of long chained alkylbenzenes comprising passing a hydrocarbon stream comprising C19 to C22 olefins and paraffins through an adsorption separation system, thereby generating an extract stream comprising C19 to C22 iso-olefins and a raffinate stream comprising paraffins, wherein the adsorbent in the adsorption separation system is a sodium based zeolite; passing the extract stream and a benzene stream to an alkylation reactor to generate an alkylbenzene process stream. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the second embodiment in this paragraph wherein the adsorption separation system uses a desorbent comprising a naphthene. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the second embodiment in this paragraph wherein the desorbent comprises a naphthene in the C5 to C10 range. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the second embodiment in this paragraph wherein the desorbent is selected from the group cyclohexane, methylcyclohexane, methylcyclopentane, cyclopentane and mixtures thereof. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the second embodiment in this paragraph further comprising passing the extract stream to a first separation unit to generate an extract process stream and an extract desorbent stream, and then passing the extract process stream to the alkylation reactor.
[0009] A third embodiment of the invention is a process for separating olefins from a hydrocarbon stream, comprising passing a feedstream to an adsorption separation system to selectively adsorb olefins, and to generate a raffinate stream having a reduced olefin content; and passing a desorbent to the adsorption separation system to displace the selectively adsorbed olefins to generate an extract stream comprising olefins; wherein the adsorbent in the adsorption separation system is a sodium substituted X zeolite, and wherein the desorbent is a naphthene. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the third embodiment in this paragraph wherein the desorbent is selected from the group consisting of cyclohexane, methylcyclohexane, methylcyclopentane, cyclopentane and mixtures thereof. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the third embodiment in this paragraph wherein the feedstream comprises paraffins and olefins in the C19 to C22 range. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the third embodiment in this paragraph further comprising passing the extract stream to a fractionation unit to generate an extract product stream and a desorbent stream.
[0010] Other objects, advantages and applications of the present invention will become apparent to those skilled in the art from the following detailed description and drawing.
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