Heavy lube oil from Fischer-Tropsch wax

Abstract

A heavy lubricant base stock is made by (a) producing a synthesis gas from natural gas, (b) reacting the H2 and CO in the gas in the presence of a cobalt Fischer-Tropsch catalyst, at reaction conditions effective to synthesize waxy hydrocarbons boiling in the heavy lubricant oil range, which are hydrodewaxed it at least two stages, with interstage separation and removal of the lighter material.

Description

[0001] This application is a Continuation-In-Part of U.S. Ser. No. 10 / 266,391 filed Oct. 8, 2002.BACKGROUND OF THE DISCLOSURE [0002] 1. Field of the Invention [0003] The invention relates to a multi-stage process for producing heavy lube oil from Fischer-Tropsch wax. More particularly the invention relates to producing a heavy lubricant base stock from wax synthesized by reacting H2 and CO produced from natural gas in the presence of a cobalt Fischer-Tropsch catalyst, by hydrodewaxing the wax in multiple stages, with interstage separation and removal of the lighter material. [0004] 2. Background of the Invention [0005] The relatively pure waxy and paraffinic hydrocarbons synthesized by the Fischer-Tropsch process, particularly over a cobalt catalyst which maximizes higher molecular weight hydrocarbon production, are excellent sources of premium lubricant oils, including heavy lubricant oil. The sulfur, nitrogen and aromatics content of the waxy hydrocarbons is essentially nil and th...

AI Technical Summary

Benefits of technology

[0009] The hydrogenating component of the hydrodewaxing catalyst will comprise at least one Group VIII metal and preferably at least one noble metal, as in platinum and palladium. The use of at least two reaction stages and a hydrodewaxing catalyst that dewaxes mostly by isomerization (e.g., a ZSM-48 component and a noble metal component), has been found to produce heavy lubricant base stocks, having acceptably low cloud and pour points, with relatively high product yield (e.g., with relatively low feed conversion to hydrocarbons boiling below the heavy lubricating oil range). Using only one hydroisomerization reaction stage, even with a hydrodewaxing catalyst comprising a ZSM-48 zeolite component and a noble metal hydrogenation component, has been found to convert substantially more of the heavy fraction, to lower boiling hydrocarbons and thereby produces less of the desirable heavy lubricant base stock oil. The multiple stage hydroisomerization process of the invention also permits each stage to operate at a lower temperature than that required for a single stage. This results in longer catalyst life and the production of a lubricant base stock containing less aromatics and other unsaturates, than is possible with a single stage. This means that at most only very mild hydrorefining of the base stock is required and this is another advantage of the process of the invention. The process of the invention is particularly useful for producing heavy lubricant base stock oils with low cloud and pour points. The use of a hydrodewaxing catalyst comprising a ZSM-48 zeolite component and a hydrogenation component, eliminates the need for hydrotreating or hydrorefining the raw, untreated Fischer-Tropsch wax feed to remove oxygenates prior to the dewaxing. The process of the invention eliminates the need for one or more separate hydrocracking, hydroisomerization, and catalytic or solvent dewaxing steps prior to hydrodewaxing, which are taught in the prior art and which substantially reduce product yield, particularly of the desired heavy lubricant base stock.

Problems solved by technology

This results in longer catalyst life and the production of a lubricant base stock containing less aromatics and other unsaturates, than is possible with a single stage.