Method of minimizing aldehyde based impurities in a process stream

Abstract

Oxidation of an alkane to an alkanone in a process stream forms aldehyde-based impurities. A method of minimizing the aldehyde-based impurities introduces an amine into the process stream to minimize the aldehyde-based impurities. The amine interacts with the alkanone and the aldehyde-based impurities thereby forming heavy products. The method separates the heavy products from the alkanones to reduce a level of the aldehyde-based impurities. The process stream preferably includes cyclohexyl ketone as the alkanone and n-hexanal as the aldehyde-based impurity. The method is typically involved in synthesis of a caprolactam.

Description

FIELD OF THE INVENTION [0001] The subject invention generally relates to a method of minimizing aldehyde-based impurities in a process stream. More specifically, the subject invention relates to introducing an amine into the process stream to minimize the aldehyde-based impurities. DESCRIPTION OF THE RELATED ART [0002] Process streams allow a constant flow of reagents to react together to form desired compounds. Typically, the process streams are used in commercial processes to synthesize the desired compounds on a large scale. For example, oxidation of alkanes to alkanones, or cyclic alkanes to cyclic alkanones, in the commercial processes is completed using the process streams. As the alkanes are oxidized to form the alkanones, many other compounds are also formed including aldehyde-based impurities. It may be desirable to separate the aldehyde-based impurities from the alkanones, i.e., from the desired compounds. This is especially important in the commercial processes that are d...

AI Technical Summary

Benefits of technology

[0011] The subject invention provides a method of minimizing aldehyde-based impurities in a process stream. The process stream includes an alkanone and the aldehyde-based impurities. The method includes the step of introducing an amine into the process stream to form a heavy product. The method also includes the step of separating the alkanone from the heavy product.

[0012] The method of minimizing the aldehyde-based impurities in the process stream, according to the subject invention, is used to decrease industrial production costs. The method utilizes the amines to form heavy products that are separated from the alkanones. By forming heavy products, the amines significantly reduce levels of the aldehyde-based impurities in the process stream. The amines also minimize self-condensation of the alkanones which, ultimately, decreases overall production costs.

Problems solved by technology

This first prior art method is deficient because simply distilling and separating the aldehyde-based impurities from the alkanones does not remove all of the aldehyde-based impurities.

Therefore, the first prior art method cannot be used in the commercial processes, such as synthesis of the caprolactam, that are dependent on pure alkanones with little or no impurities.

This second prior art method is deficient because use of the basic hydroxide or carbonate promotes a self-condensation of the alkanones to produce polymeric alkanones.

Polymerization of the alkanones renders the alkanones unusable for further processing in many commercial processes, such as synthesis of the caprolactam.

Also, because the second prior art method results in up to a 25% loss of the alkanones to self-condensation, production costs are increased.

Further, commercially available alkanes, the starting materials of the alkanones, and specifically cyclic alkanes, are particularly expensive.

Therefore, this second prior art method is not efficient for use in the commercial processes due to increased production costs.

As described above, polymerizing the alkanones renders the alkanones unusable for further processing in many commercial processes, such as synthesis of the caprolactam.

The '329 application does not disclose use of amines to minimize the aldehyde-based impurities in a process stream or any method that would not promote the self-condensation of the alkanones.

Therefore, the method disclosed in the '329 application is not suitable for use in the commercial processes, such as the synthesis of caprolactam, that are dependent on pure alkanones with little or no impurities.

Therefore, the method disclosed in the '848 publication is not suitable for use in the commercial processes, such as synthesis of the caprolactam, that are dependent on pure, monomeric cyclic alkanones with little or no impurities.

The various prior art methods described above are not suitable for use in the commercial processes, such as synthesis of the caprolactam, for a variety of reasons.

These prior art methods have not been optimized for use in the commercial processes to reduce the production costs.

Any self-condensation of the alkanones reduces useable products and increases the production costs.

Also, distilling and separating the aldehyde-based impurities from the alkanones does not easily eliminate all of the aldehyde-based impurities in practice.

Therefore, neither of the prior art methods can be used in cost efficient commercial processes that are dependent on pure alkanones with little or no impurities.

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