US 5,399,258 A · Hydrocarbon upgrading process

Abstract

Low sulfur gasoline of relatively high octane number is produced from a catalytically cracked, sulfur-containing naphtha by hydrodesulfurization followed by treatment over an acidic catalyst under endothermic conditions in a second reaction zone. Heat is added to the endothermic reaction zone to initiate and maintain octane restoring reactions. The preferred acidic catalyst is an intermediate pore size zeolite such as ZSM-5. The treatment over the acidic catalyst in the second step restores the octane loss which takes place as a result of the hydrogenative treatment and results in a low sulfur gasoline product with an octane number comparable to that of the feed naphtha. The addition of heat at the second zone prolongs hydrodesulfurization catalyst life by allowing a lower hydrodesulfurization reactor temperature. The addition of heat also maximizes octane increase in the second zone.

Claims28

Dependent claims

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

contacting the sulfur-containing catalytically cracked fraction having a 95% point of at least about 325.degree. F. and boiling in the gasoline boiling range with a hydrodesulfurization catalyst in a first reaction zone, operating under a combination of elevated temperature, elevated pressure and an atmosphere comprising hydrogen, to produce an intermediate product comprising a normally liquid fraction high in paraffins which has a reduced sulfur content and a reduced octane number as compared to the feed;
contacting at least the gasoline boiling range portion of the intermediate product in a second reaction zone with a catalyst of acidic functionality under a condition of elevated temperature to convert it to a product high in olefins comprising a fraction boiling in the gasoline boiling range having a higher octane number than the gasoline boiling range fraction of the intermediate product;
and
providing sufficient heat to the second reaction zone to maintain the temperature of at least a portion of the second reaction zone to at least the same temperature as the temperature of at least a portion of the first reaction zone.

1 more element

A process of upgrading a sulfur-containing feed fraction boiling in the gasoline boiling range which comprises:

contacting the sulfur-containing feed fraction with a hydrodesulfurization catalyst in a first reaction zone, operating under a combination of elevated temperature, elevated pressure and an atmosphere comprising hydrogen, to produce an intermediate product comprising a normally liquid fraction which has a reduced sulfur content and a reduced octane number as compared to the feed;
contacting at least the gasoline boiling range portion of the intermediate product in a second reaction zone with a catalyst of acidic functionality under a condition of elevated temperature to convert it to a product comprising a fraction boiling in the gasoline boiling range having a higher octane number than the gasoline boiling range fraction of the intermediate product;
controlling the octane of the product by providing heat to the second reaction zone;
maintaining the temperature of the second reaction zone above the temperature of the first reaction zone until the sulfur content of the intermediate product substantially increases in response to aging of the hydrodesulfurization catalyst;
elevating the temperature of the first reaction zone above the temperature of the second reaction zone to reduce the sulfur content of the intermediate product;
and
controlling the temperature of the second reaction zone by introducing a quenching fluid to the second reaction zone to avoid aging of the catalyst of the second reaction zone.

4 more elements

Dependencies are inferred from the claim text.

Hydrocarbon upgrading process

Life of this patent

Hydrocarbon upgrading process

Life of this patent

Abstract

Claims28