Increasing octane number of light naphtha using a germanium-zeolite catalyst

Abstract

This invention relates to a process for the increasing the octane number of a naphtha hydrocarbon feed having a predominantly paraffin content with a germanium-containing zeolite catalyst. The catalyst is a non-acidic germanium zeolite on which a noble metal, such as platinum, has been deposited. The zeolite structure may be of MTW, MWW, MEL, TON, MRE, FER, MFI, BEA, MOR, LTL or MTT. The zeolite is made non-acidic by being base-exchanged with an alkali metal or alkaline earth metal, such as cesium, potassium, sodium, rubidium, barium, calcium, magnesium and mixtures thereof, to reduce acidity. The catalyst is sulfur tolerant. The hydrocarbon feed may contain sulfur up to 1000 ppm. The present invention could be applicable to a feedstream which is predominantly naphthenes and paraffins.

Description

BACKGROUND OF THE INVENTION[0001]1. Field of the Invention[0002]This invention relates to a process for the increasing the octane number of a naphtha hydrocarbon feed having a predominantly paraffin content with a base-exchanged zeolite with germanium in the crystalline framework and with a noble metal deposited on the zeolite, for example Pt / CsGeZSM-5.[0003]2. Description of the Prior Art[0004]Naphtha is a mixture mainly of straight-chained, branched and cyclic aliphatic hydrocarbons, light naphtha having from five to nine carbon atoms per molecule and heavy naphtha having from seven to nine carbons per molecule. Typically, light naphtha contains naphthenes, such as cyclohexane and methylcyclopentane, and linear and branched paraffins, such as hexane and pentane. Light naphtha typically contains 60% to 99% by weight of paraffins and cycloparaffins. Light naphtha can be characterized as a petroleum distillate having a molecular weight range of 70-150 g / mol, a specific gravity range ...

AI Technical Summary

Benefits of technology

[0013]The octane number of a naphtha hydrocarbon feed with a predominantly paraffin content is increased by contacting the hydrocarbon feed with a catalyst which comprises a non-acidic germanium zeolite on which a noble metal, such as platinum, has been deposited. The zeolite is non-acidic. Examples of the zeolite structure are MTW, FER, MEL, TON, MRE, MWW, MFI, BEA, MOR, LTL or MTT. In one embodiment of the invention the zeolite has a MFI structure. The term “ZSM-5” is used in this Specification to mean a zeolite having a MFI structure. The zeolite has silicon, germanium and, optionally, aluminum in the crystalline framework of the zeolite structure. One example of the catalyst is an aluminosilicate zeolite having germanium in the framework which has been base-exchanged such that it is nonacidic and on which platinum has been deposited, e.g., Pt / CsGeZSM-5. This catalyst is sulfur tolerant up to a level of 1000 ppm in the hydrocarbon feed.

[0014]The process for increasing octane number of a hydrocarbon feed comprising: a) contacting at conditions for concurrently isomerizing n-paraffins to isoparaffins, further isomerizing isoparaffins to more highly branched isoparaffins, cracking n-paraffins to smaller n-isoparaffins, dehydrogenating both n- and iso- paraffins and dehydrocyclizing n-paraffins to aromatics a hydrocarbon feed comprising naphtha having C6-C8 alkanes, with a catalyst comprising a non-acidic medium pore or large pore zeolite comprising silicon, germanium and, optionally, aluminum on which a noble metal has been deposited; and b) recovering a hydrocarbon product. The naphtha feed may have a C6-C8 content of at least 30%, at least 40% or at least 50%.

Problems solved by technology

Catalytic reforming can increase octane number by converting a portion of paraffins and cycloparaffins to aromatics but a platinum type reforming catalyst is generally not sulfur tolerant.

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