Process for producing diesel fuel and jet fuel from biorenewable feedstocks

Abstract

A process has been developed for producing diesel fuel or jet fuel from renewable feedstocks such as fats and oils from plants and animals. The process involves producing a hydrogen-rich mixture in a reformer, hydrolyzing a renewable feedstock to produce a free fatty acid stream and a glycerol-containing stream, catalytically treating the free fatty acid stream by hydrogenating and deoxygenating to provide a hydrocarbon fraction useful as a diesel fuel or jet fuel. A selective separation such as a hot high pressure hydrogen stripper may be used to remove at least the carbon oxides from the reaction zone effluent and provide a liquid recycle stream at pressure and temperature. A vapor stream is separated from the effluent and at least carbon dioxide is removed using at least one amine absorber. The resulting hydrogen-rich stream is recycled to the reaction zone.

Description

FIELD OF THE INVENTION[0001]This invention relates to a process for producing diesel boiling range fuel and jet fuel from renewable feedstocks such as the triglycerides and free fatty acids found in materials such as plant oils, fish oils, animal fats, and greases. Hydrogenation and deoxygenation are performed in one or more reactors without use of expensive purified hydrogen. One or more sulfur compounds may be present in the reaction mixture. A vapor stream is separated from the reaction zone effluent, and carbon dioxide is separated from the vapor stream. Optionally, a sulfur-containing stream may also be separated.BACKGROUND OF THE INVENTION[0002]As the demand for diesel boiling range fuel and jet fuel increases worldwide there is increasing interest in sources other than crude oil for producing diesel boiling range fuel and jet fuel. One such renewable source is what has been termed biorenewable sources. These renewable sources include, but are not limited to, plant oils such a...

AI Technical Summary

Benefits of technology

[0006]A process for producing a diesel fuel or jet fuel product (also referred to as hydrocarbon fuel, including diesel fuel and / or jet fuel) from a renewable feedstock wherein the process comprises generating a hydrogen-rich mixture in a steam fuel reformer, treating the feedstock in a catalytic reaction zone by hydrogenating and deoxygenating the feedstock at reaction conditions to provide a reaction product comprising a hydrocarbon fraction comprising paraffins and a gaseous fraction comprising at least carbon dioxide and hydrogen. At least one sulfur containing component may be present in the reaction mixture. The sulfur containing component may be present as a naturally occurring contaminant or may be intentionally added to the feedstock or reaction mixture. Many sulfur containing components will form hydrogen sulfide in the reactor. The renewable feedstock may go through an optional hydrolysis process to produce a free fatty acid (FFA) stream and glycerol. The glycerol is separated out and the FFA stream is sent to the reaction zone (also called the deoxygenation reactor) where hydrogenation and deoxygenation occur. It takes 3 molecules of hydrogen to convert a molecule of glycerol to a molecule of propane in a hydrodeoxygenation reaction. The removal of glycerol from the reaction zone therefore reduces the consumption of hydrogen significantly.

Problems solved by technology

The processes in these two patents have several major shortcomings: first they relied on the use of purified hydrogen, which are expensive and energy consuming to produce; second, these processes used excessive amount of hydrogen, partly due to converting the glycerol component in the triglycerides into propane; third, the hydrogen used in these processes are often derived from natural gas, which could be a fossil fuel and a non-renewable source.

The use of a large amount of fossil fuel in the production process of a renewable fuel undermines the appeal of the renewable fuel.

The purification of hydrogen by removal of carbon oxides is itself an expensive and energy intensive process.

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