Catalytic distillation hydroprocessing

Abstract

A method for hydroprocessing a hydrocarbon synthesis product feed to form upgraded fuels and lubricating oils. In a preferred embodiment, the method includes the steps of: (a) contacting a Fischer-Tropsch product with a hydroprocessing catalyst to produce a desired distillate; and (b) counter-currently stripping the desired distillate as it is produced. The method may include distilling the desired distillate or distilling the treated Fischer-Tropsch product.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS [0001] None. FIELD OF THE INVENTION [0002] The present invention relates to the hydroprocessing of a hydrocarbon feedstock. More particularly, the present invention relates to a method and apparatus for controlling the production of naphtha and lighter products and improving efficiency in a hydroprocessing process. Still more particularly, the invention relates to a method and apparatus for controlling naphtha and lighter hydrocarbons production and improving efficiency in a hydroprocessing process using a catalytic distillation process. BACKGROUND OF THE INVENTION [0003] Crude petroleum is a mixture of many different hydrocarbon molecules, ranging in size from very small to very large. The number of carbon atoms that a molecule contains generally governs the size of the molecule. The petroleum refining process initially entails separation of these compounds by boiling point. The boiling point is dependent on the size and structure of the mole...

AI Technical Summary

Benefits of technology

[0011] In a preferred embodiment of the present invention, a method is provided for increasing the efficiency and output of a hydroprocessing unit engaged in hydroprocessing products of a hydrocarbon synthesis process by removing middle distillate and lighter components from the reaction zone as they are produced, thereby minimizing unwanted secondary cracking of the hydrocarbons already in the desired range. These components are removed by a catalytic distillation system that selectively vaporizes lighter components as they are made. Such a system is capable of creating one or more distillate products from a heavy hydrocarbon synthesis wax product. Another embodiment of the present invention provides an apparatus for catalytically distilling a hydrocarbon synthesis product and recovering one or more distillate products while reducing excess naphtha and lighter hydrocarbons production.

Problems solved by technology

However, the probability that a bond that is three carbons from the end of a hydrocarbon chain will crack is about half of that of bonds that are four or more carbons from the end.

Thus, large hydrocarbon molecules may crack into middle distillates and further crack into lighter hydrocarbons before leaving the reactor generating excess naphtha.

Besides isomerization, hydroisomerization may also produce some cracking.

Further, as mentioned above, some hydroprocessing processes are more susceptible to selectivity problems.

Processes that are more susceptible include those in which the feedstock has a higher paraffin content, as paraffins crack much more easily than aromatics and are more likely to continue cracking to lighter components.

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