US 5,318,690 A · Gasoline upgrading process

Abstract

Low sulfur gasoline is produced from a catalytically cracked, sulfur-containing naphtha by fractionating the naphtha feed into a low boiling fraction in which the majority of the sulfur is present in the form of mercaptans and a high-boiling fraction in which the sulfur is predominantly in non-mercaptan form such as thiophenes. The low boiling fraction is desulfurized by a non-hydrogenatile mercaptan extraction process which retains the olefins present in this fraction. The second fraction is desulfurized by hydrodesulfurization, which results in some saturation of olefins and loss of octane. The octane loss is restored by treatment over an acidic catalyst, preferably an intermediate pore size zeolite such as ZSM-5, to form a low sulfur gasoline product with an octane number comparable to that of the feed naphtha but which contains some recombined sulfur in the form or mercaptans which are removed in a final hydrotreatment.

Claims23

Dependent claims

A process of upgrading a sulfur-containing cracked feed in the gasoline boiling range having a 95 percent point of at least about 325.degree. F. which comprises:

fractionating the feed to form a first fraction and a second fraction which boils above the first fraction,
desulfurizing the first fraction by a non-hydrogenative mercaptan removal process to form a first desulfurized product in the gasoline boiling range,
hydrodesulfurizing the second fraction in the presence of a hydrodesulfurization catalyst under conditions of elevated temperature, elevated pressure and in an atmosphere comprising hydrogen, to produce a desulfurized first intermediate product;
contacting the desulfurized first intermediate product with a catalyst of acidic functionality to convert it to a second intermediate product comprising a fraction boiling in the gasoline boiling range having a higher octane number than the gasoline boiling range fraction of the desulfurized first intermediate product and containing combined organic sulfur,
hydrodesulfurizing the second intermediate product to form a second desulfurized product in the gasoline boiling range.

2 more elements

A process of upgrading a catalytically cracked, olefinic, sulfur-containing gasoline feed having a sulfur content of at least 50 ppmw, an olefin content of at least 5 percent and a 95 percent point of at least 325.degree. F., which process comprises:

separating the sulfur-containing feed into (i) a first sulfur-containing fraction which contains olefins and sulfur components in the form of mercaptans and (ii) a second sulfur-containing fraction in which the sulfur components are present predominantly in non-mercaptan form and which boils above the first fraction,
desulfurizing the first fraction by removal of the mercaptans without saturation of the olefins present in the first fraction to form a first desulfurized product in the gasoline boiling range,
hydrodesulfurizing the second fraction under conditions of elevated temperature, elevated pressure and in an atmosphere comprising hydrogen, to produce a first desulfurized intermediate product comprising a normally liquid fraction which has a reduced sulfur content and a reduced octane number as compared to the second sulfur-containing fraction;
contacting the gasoline boiling range portion of the first desulfurized intermediate product with an acidic zeolite catalyst to form a second intermediate product comprising a fraction boiling in the gasoline boiling range having a higher octane number than the gasoline boiling range fraction of the first desulfurized intermediate product and containing combined organic sulfur in the form of mercaptans,
hydrodesulfurizing the second intermediate product to form a second desulfurized product in the gasoline boiling range,
combining the first desulfurized product with the second desulfurized product.

3 more elements

Dependencies are inferred from the claim text.

Gasoline upgrading process

Life of this patent

Gasoline upgrading process

Life of this patent

Abstract

Claims23