Combination Of Mild Hydrotreating And Hydrocracking For Making Low Sulfur Diesel And High Octane Naphtha

PATENT
Combination Of Mild Hydrotreating And Hydrocracking For Making Low Sulfur Diesel And High Octane Naphtha
United States Patent Application 20120043257 Kind Code:A1
Inventors:
Dziabala, Bart (Hickory Hills, IL, US)
Thakkar, Vasant P. (Elk Grove Village, IL, US)
Abdo, Suheil F. (Lincolnshire, IL, US)
Application Number: 13/286769
Publication Date: 02/23/2012
Assignee: UOP LLC (Des Plaines, IL, US)
Abstract:
Methods are disclosed for the hydrotreating and hydrocracking of highly aromatic distillate feeds such as light cycle oil (LCO) to produce ultra low sulfur gasoline and diesel fuel. Optimization of hydrotreater severity improves the octane quality of the gasoline or naphtha fraction. In particular, the operation of the hydrotreater at reduced severity to allow at least about 20 ppm by weight of organic nitrogen into the hydrocracker feed is shown to lead to these important benefits. Post-treating of the hydrocracker effluent over an additional hydrotreating catalyst bed may be desired to meet specifications for ultra low sulfur fuel components.
FIELD OF THE INVENTION
The present invention relates to methods for converting petroleum distillates, such as highly aromatic feedstocks, using a combination of mild hydrotreating and hydrocracking to provide diesel and naphtha products, especially ultra low sulfur diesel and high octane naphtha.
DESCRIPTION OF RELATED ART
Petroleum refiners produce desirable products such as diesel fuel, naphtha, and gasoline, by hydrocracking a hydrocarbon feedstock, normally derived from crude oil. Distillate feedstocks often subjected to hydrocracking are gas oils and heavy gas oils recovered from crude oil by distillation. For example, U.S. Pat. No. 4,943,366 discloses a hydrocracking process for converting highly aromatic, substantially dealkylated feedstock into high octane gasoline.
Refiners also subject distillate hydrocarbon streams to hydrotreating operations such as hydrodesulfurization. To achieve currently mandated standards for ultra low sulfur diesel and gasoline, hydrotreating is being performed under high severity conditions, including high temperatures and pressures and low space velocities. The ability to upgrade the distillate known as Light Cycle Oil (LCO), obtained from fluid catalytic cracking (FCC) refinery operations, is of particular interest in view of the limited uses of this low-value material. However, high severity LCO hydrotreating often leads to excessive hydrogen consumption with only modest diesel quality upgrade in terms of cetane improvement.
There is consequently a demand for new hydroprocessing methods which can effectively upgrade distillate feedstocks such as LCO to more highly valuable products including diesel and naphtha. Ideally, these products, and especially diesel, should have a sufficiently low sulfur content to meet applicable standards. Naphtha should have a sufficiently high octane number for use in gasoline blending.
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