Processes

• US 4,367,135 A
• Filed: 03/12/1981
• Issued: 01/04/1983
• Est. Priority Date: 03/12/1981
• Status: Expired due to Term

• Current Assignee: Permea Incorporated
• Original Assignee: Monsanto Company (Bayer AG)
• Inventors: Posey, Lloyd G. Jr.
• Primary Examiner(s): Metz, Andrew
• Assistant Examiner(s): Schmitkons, G. E.
• Application Number:
  US06/243,220
• Time in Patent Office: 663 Days
• Field of Search: 208/108, 208/102, 55/16
• US Class Current: 208/108
• CPC Class Codes: C01B 2203/0405 Purification by membrane separation
• CPC Class Codes: C01B 2203/048 the impurity being an organic compound
• CPC Class Codes: C01B 3/501 by diffusion
• CPC Class Codes: C10G 49/22 Separation of effluents

Abstract

Efficient utilization of hydrogen in a hydrocracking system is obtained by recovering in a first gas-liquid separation zone hydrogen by gas-liquid separation of hydrocrackate at a pressure of at least about 75 percent of the pressure in the hydrocracking zone, and recovering in a second gas-liquid separation zone hydrogen from the separated liquid phase from the first gas-liquid separation zone, said second gas-liquid separation zone being at a pressure less than 75 percent of the pressure in the first gas-liquid separation zone and at conditions sufficient to provide a separated vapor phase containing at least about 50 volume percent of hydrogen and having a hydrogen partial pressure of at least about 20 atmospheres. At least a portion of the separated vapor phase from the second gas-liquid separation zone is contacted with the feed side of a polymeric membrane exhibiting a high selectivity to the permeation of hydrogen as compared to the permeation of methane. The opposite side, i.e., permeate side, of the membrane is maintained at a pressure sufficiently below the pressure on the feed side of the membrane such that the ratio of the total pressure on the feed side to total pressure on the permeate side of the membrane is at least about 3:1 to permeate hydrogen to the permeate side of the membrane and provide a hydrogen permeate having a concentration of hydrogen greater than the concentration of hydrogen in the separated vapor phase contacting the membrane. At least a portion of the hydrogen permeate is recycled to the hydrocracking zone. Thus, the second gas-liquid separation zone co-acts with the polymeric membrane separation to provide a highly useable, recovered hydrogen stream in the hydrocracking system.

Claims

1. A process for catalytically hydrocracking a hydro-carbonaceous feed comprising:

a. cracking in a hydrocracking zone the hydro-carbonaceous feed in the presence of hydrogen and a hydrocracking catalyst under hydro-cracking conditions comprising a temperature of at least about 250°

C. and a pressure of at least about 75 atmospheres absolute to produce a hydrocrackate wherein the hydrogen is provided in a hydrogen feed gas, said hydrogen feed gas being provided in an amount sufficient to promote hydrocracking and having a concentration of hydrogen sufficient to prevent unduly rapid deactivation of the hydrocracking catalyst;

b. passing the hydrocrackate to a first gas-liquid separation zone, said first gas-liquid separation zone being at a pressure of at least about 75 percent of the pressure in the hydrocracking zone;

c. separating the hydrocrackate in the first gas-liquid separation zone into a first separated vapor phase and a first separated liquid phase;

d. passing the first separated liquid phase to a second gas-liquid separation zone, the pressure of said first separated liquid phase in said second zone being between about 35 atmospheres absolute and the pressure of said first zone;

e. separating the first separated liquid phase in the second gas-liquid separation zone into a second separated liquid phase and a second separated vapor phase, said second gas-liquid separation zone being maintained at a pressure and temperature sufficient such that the second separated vapor phase has a concentration of hydrogen of at least about 50 volume percent and a hydrogen partial pressure of at least about 20 atmospheres;

f. contacting at least a portion of the second separated vapor phase with a feed side of a polymeric membrane exhibiting a separation factor of hydrogen over methane of at least about 15;

g. maintaining the opposite side of the membrane at a pressure sufficiently below the pressure of the second separated vapor phase contacting the feed side of the membrane to permeate at least 70 percent of the hydrogen from the vapor phase to the opposite side of the membrane and to provide a hydrogen permeate having a concentration of at least 80 volume percent at a pressure of at least 8 atmospheres absolute, the ratio of the total pressure on the feed side of the membrane to the total pressure on the opposite side of the membrane being at least about 3;

1;

h. withdrawing non-permeate from the feed side of the membrane; and

removing the hydrogen permeate from the opposite side of the membrane; and

i. recycling at least a portion of the hydrogen permeate to the hydrocracking zone as a portion of the hydrogen feed gas.