Process for the dehydrogenation of hydrocarbons

• US 4,778,942 A
• Filed: 03/14/1988
• Issued: 10/18/1988
• Est. Priority Date: 03/14/1988
• Status: Expired due to Term

• Current Assignee: UOP A New York General Partnership
• Original Assignee: UOP Llc (Honeywell International Inc.)
• Inventors: Vora, Bipin V., Scott, Norman H.
• Primary Examiner(s): Davis, Curtis R.
• Application Number:
  US07/168,098
• Time in Patent Office: 218 Days
• Field of Search: 585/655, 585/660
• US Class Current: 585/655
• CPC Class Codes: C07C 5/325 of the platinum group

Abstract

A process for the dehydrogenation of a dehydrogenatable hydrocarbon feedstock having small quantities of higher boiling range hydrocarbons which comprises: (a) introducing the dehydrogenatable hydrocarbon feedstock into a fractionation zone having at least a portion of reflux to a fractionation column supplied by a hereinafter-described recycle stream to provide a dehydrogenatable hydrocarbon stream having a reduced concentration of higher boiling range hydrocarbons and a stream comprising the higher boiling range hydrocarbons; (b) introducing the dehydrogenatable hydrocarbon stream having a reduced concentration of higher boiling range hydrocarbon recovered in step (a) into a dehydrogenation zone containing dehydrogenation catalyst and operated at dehydrogenation conditions to provide a hydrocarbon stream comprising dehydrogenated hydrocarbons and unconverted dehydrogenatable hydrocarbons; (c) separating the hydrocarbon stream comprising dehydrogenated hydrocarbons and unconverted dehydrogenatable hydrocarbons from step (b) to provide a product stream comprising dehydrogenated hydrocarbons and a recycle stream comprising unconverted dehydrogenatable hydrocarbons; (d) introducing the recycle stream comprising unconverted dehydrogenatable hydrocarbons recovered in step (c) into the fractionation column to provide at least a portion of reflux to the fractionation column as described hereinabove in step (a).

Claims

1. A process for the dehydrogenation of a dehydrogenatable hydrocarbon feedstock having small quantities of higher boiling range hydrocarbons which comprises:

(a) introducing said dehydrogenatable hydrocarbon feedstock into a fractionation zone having at least a portion of reflux to a fractionation column supplied by a hereinafter described recycle stream to provide a dehydrogenatable hydrocarbon stream having a reduced concentration of higher boiling range hydrocarbons and a stream comprising said higher boiling range hydrocarbons;

(b) introducing said dehydrogenatable hydrocarbon stream having a reduced concentration of higher boiling range hydrocarbon recovered in step (a) into a dehydrogenation zone containing dehydrogenation catalyst and operated at dehydrogenation conditions to provide a hydrocarbon stream comprising dehydrogenated hydrocarbons and unconverted dehydrogenatable hydrocarbons;

(c) separating said hydrocarbon stream comprising dehydrogenated hydrocarbons and unconverted dehydrogenatable hydrocarbons from step (b) to provide a product stream comprising dehydrogenated hydrocarbons and a recycle stream comprising unconverted dehydrogenatable hydrocarbons;

(d) introducing said recycle stream comprising unconverted dehydrogenatable hydrocarbons recovered in step (c) into said fractionation column to provide at least a portion of reflux to said fractionation column as described hereinabove in step (a).

2. The process of claim 1 wherein said dehydrogenatable hydrocarbon feedstock is selected from the group consisting of ethane, propane, butane, and pentane.

3. The process of claim 1 wherein said higher boiling range hydrocarbons are present in said dehydrogenatable hydrocarbon feedstock in an amount less than about 10 weight percent.

4. The process of claim 1 wherein said dehydrogenation conditions include a temperature from about 1022°

F. (550°

C.) to about 1472°

F. (800°

C.), a pressure from about 0.01 to about 10 atmospheres absolute, a liquid hourly space velocity from about 0.1 to about 100 hr^-1 and a hydrogen to hydrocarbon mole ratio from about 0.01;

1 to about 40;

1.

5. The process of claim 1 wherein said dehydrogenation catalyst comprises a platinum group metal component, an alkali metal component and a porous inorganic carrier material.

6. The process of claim 1 wherein said step (c) is conducted in a separation zone comprising a de-ethanizer fractionation column and a propylene fractionation column.

7. The process of claim 1 wherein said dehydrogenatable hydrocarbon feedstock comprises propane and small quantities of butane.