# US 9,517,981 B2 · Membrane-based gas separation processes to separate dehydrogenation reaction products

> Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt

- Number: US 9,517,981 B2
- Document ID: US9517981B2
- Status: Granted
- Kind: B2
- Application number: 14/099,267
- Filed: 2013-12-06
- Published: 2015-06-11
- Granted: 2016-12-13
- Earliest claimed: 2013-12-06
- Assignees: Membrane Technology and Research, Inc.
- Applicants: Nicholas P. Wynn; Alvin Ng; Douglas Gottschlich; Paul Su; Meijuan Zhou; Sylvie Thomas-Droz
- Inventors: Nicholas P. Wynn; Alvin Ng; Douglas Gottschlich; Paul Su; Meijuan Zhou; Sylvie Thomas-Droz
- Web page: https://patentgrep.com/patent/US9517981B2

## CPC

- C07C 7/005: {Processes comprising at least two steps in series}
- B01D 53/002: {by condensation}
- B01D 53/22: by diffusion (manufacturing semi-permeable membranes B01D67/00; form, structure or properties of semi-permeable membranes B01D69/00; material for semi-permeable membranes B01D71/00)
- B01D 53/226: {in serial connexion}
- C01B 3/501: by diffusion
- C07C 7/144: using membranes, e.g. selective permeation
- F25J 3/0271: {separation of H2/CO mixtures, i.e. of synthesis gas (production of carbon monoxide containing gas in general C01B32/40, C10J, C10K, production of hydrogen containing gas C01B3/00)}
- C01B 2203/0266: containing a decomposition step
- C01B 2203/041: In-situ membrane purification during hydrogen production
- C01B 2203/043: Regenerative adsorption process in two or more beds, one for adsorption, the other for regeneration
- C01B 2203/147: Three or more purification steps in series
- C01B 2203/148: involving a recycle stream to the feed of the process for making hydrogen or synthesis gas
- F25J 2205/80: using membrane, i.e. including a permeation step
- F25J 2270/90: External refrigeration, e.g. conventional closed-loop mechanical refrigeration unit using Freon or NH3, unspecified external refrigeration
- C07C: ACYCLIC OR CARBOCYCLIC COMPOUNDS
- B01D: SEPARATION (separating solids from solids by wet methods B03B, B03D; by pneumatic jigs or tables B03B; by other dry methods B07; magnetic or electrostatic separation of solid materials from solid materials or fluids, separation by high-voltage electric fields B03C; centrifuges, vortex apparatus B04; presses per se for squeezing-out liquid from liquid-containing material B30B9/02; treatment of water C02F, e.g. softening by ion-exchange C02F1/42; {arrangements of air intake cleaners in gas turbine plants F02C7/05} ; arrangements or mounting of filters in air-conditioning, air-humidification or ventilation F24F13/28)
- C01B: NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; {METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C}
- F25J: LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS {OR LIQUEFIED GASEOUS} MIXTURES BY PRESSURE AND COLD TREATMENT {OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE (cryogenic pumps F04B37/08; gas storage vessels, gas holders F17; filing vessels with, or discharging from vessels, compressed, liquefied or solidified gases F17C; refrigeration machines, plants, or systems F25B)}

## Abstract

Gas separation processes are provided for separating dehydrogenation reaction products from a raw gas stream to recover hydrocarbons, specifically olefins, such as propylene and iso-butene, as well as unreacted feedstock. The processes employ a sequence of partial condensation steps, interspersed with membrane separation steps to raise the hydrocarbon dewpoint of the uncondensed gas, thereby avoiding the use of low-temperature or cryogenic conditions.

## Claims

### Claim 1

A process for treating a raw product stream from dehydrogenation of a light paraffin, said raw product stream comprising at least one paraffin component, one olefin component and hydrogen, comprising the sequential steps of:
(a) compressing the raw product stream to create a compressed stream having a first hydrocarbon dewpoint;
(b) partially condensing the compressed stream, including cooling and separating the compressed stream into a first hydrocarbon condensate stream and a first uncondensed gas stream;
(c) heating the first uncondensed gas stream from step (b);
(d) separating the first uncondensed gas stream from step (c) using a first membrane to remove a hydrogen-rich permeate gas stream and create a hydrocarbon-enriched residue gas stream having a first residue hydrocarbon dewpoint that is within 15° C. of the first hydrocarbon dewpoint; and
(e) partially condensing the residue gas stream, including cooling and separating the residue gas stream into a second hydrocarbon condensate and a second uncondensed gas stream; and
(f) separating the second uncondensed gas stream from step (e) using a second membrane to remove a hydrocarbon-rich permeate gas stream; and
(g) recompressing and recirculating the hydrocarbon-rich permeate gas stream to step (b).

### Claim 2

A process for treating a raw product stream from dehydrogenation of a light paraffin, said raw product stream comprising at least one paraffin component, one olefin component and hydrogen, comprising the sequential steps of:
(a) compressing the raw product stream to create a compressed stream having a first hydrocarbon dewpoint;
(b) partially condensing the compressed stream, including cooling to a temperature no lower than −30° C. and separating the compressed stream into a first hydrocarbon condensate stream and a first uncondensed gas stream;
(c) heating the first uncondensed gas stream from step (b);
(d) separating the first uncondensed gas stream from step (c) using a first membrane to remove a hydrogen-rich permeate gas stream and create a hydrocarbon-enriched residue gas stream having a first residue hydrocarbon dewpoint; and
(e) partially condensing the residue gas stream, including cooling to a temperature no lower than −30° C. and separating the residue gas stream into a second hydrocarbon condensate and a second uncondensed gas stream; and
(f) separating the second uncondensed gas stream from step (e) using a second membrane to remove a hydrocarbon-rich permeate gas stream; and
(g) recompressing and recirculating the hydrocarbon-rich permeate gas stream to step (b).

### Claim 3 (depends on 1, 2)

The process of claims 1 or 2, wherein the olefin component is propylene.

### Claim 4 (depends on 1, 2)

The process of claims 1 or 2, wherein the olefin component is iso-butene.

### Claim 5 (depends on 1, 2)

The process of claims 1 or 2, wherein steps (b) and (e) use a water coolant.

### Claim 6 (depends on 1, 2)

The process of claims 1 or 2, wherein steps (b) and (e) use a refrigerant coolant.

### Claim 7 (depends on 1, 2)

The process of claims 1 or 2, wherein step (b) reduces the dewpoint of the compressed stream between 20° C. and 50° C.

### Claim 8 (depends on 1, 2)

The process of claims 1 or 2, wherein step (d) increases the dewpoint of the hydrocarbon-enriched residue stream between 20° C. and 50° C.

### Claim 9 (depends on 1, 2)

The process of claims 1 or 2, wherein the first residue hydrocarbon dewpoint is within 10° C. of the first hydrocarbon dewpoint.

### Claim 10 (depends on 1, 2)

The process of claims 1 or 2, wherein the membrane of step (d) has a hydrogen permeance of at least 200 gpu under process operating conditions.

### Claim 11 (depends on 1, 2)

The process of claims 1 or 2, wherein the membrane of step (d) has a selectivity of hydrogen over propylene of at least 30 under process operating conditions.

### Claim 12 (depends on 1, 2)

The process of claims 1 or 2, wherein the membrane of step (d) has a selectivity of hydrogen over iso-butene of at least 100 under process operating conditions.

### Claim 13 (depends on 1, 2)

The process of claims 1 or 2, further comprising the steps of:
(g) separating the hydrogen-rich permeate gas stream from step (d) using a pressure swing adsorption unit to remove a second hydrogen-rich permeate gas stream and create a hydrocarbon-enriched tail gas stream; and
(h) recompressing and recirculating the hydrocarbon-enriched tail gas stream to step (c).

### Claim 14

A process for treating a raw product stream from dehydrogenation of a light paraffin, said raw product stream comprising at least one paraffin component, one olefin component and hydrogen, comprising the sequential steps of:
(a) compressing the raw product stream to create a compressed stream having a first hydrocarbon dewpoint;
(b) partially condensing the compressed stream, including cooling and separating the compressed stream into a first hydrocarbon condensate steam and a first uncondensed as stream;
(c) heating the first uncondensed gas stream from step (b);
(d) separating the first uncondensed gas stream from step (c) using a first membrane to remove a hydrogen-rich permeate gas stream and create a hydrocarbon-enriched residue gas stream having a first residue hydrocarbon dewpoint that is within 15° C. of the first hydrocarbon dewpoint;
(e) partially condensing the residue gas stream, including cooling and separating the residue gas stream into a second hydrocarbon condensate and a second uncondensed gas stream
(f) recirculating at least a first portion of the second uncondensed gas stream to step (c);
(g) separating a second portion of the second uncondensed gas stream from step (e) using a second membrane to remove a hydrocarbon-rich permeate gas stream; and
(h) recompressing and recirculating the hydrocarbon-rich permeate gas stream to step (b).

### Claim 15

A process for treating a raw product stream from dehydrogenation of a light paraffin, said raw product stream comprising at least one paraffin component, one olefin component and hydrogen, comprising the sequential steps of:
(a) compressing the raw product stream to create a compressed stream having a first hydrocarbon dewpoint;
(b) partially condensing the compressed stream, including cooling to a temperature no lower than −30° C. and separating the compressed stream into a first hydrocarbon condensate stream and a first uncondensed gas stream;
(c) heating the first uncondensed gas stream from step (b);
(d) separating the first uncondensed gas stream from step (c) using a first membrane to remove a hydrogen-rich permeate gas stream and create a hydrocarbon-enriched residue gas stream having a first residue hydrocarbon dewpoint;
(e) partially condensing the residue gas stream, including cooling to a temperature no lower than −30° C. and separating the residue gas stream into a second hydrocarbon condensate and a second uncondensed gas stream;
(f) recirculating at least a first portion of the second uncondensed gas stream to step (c);
(g) separating a second portion of the second uncondensed gas stream from step (e) using a second membrane to remove a hydrocarbon-rich permeate gas stream; and
(h) recompressing and recirculating the hydrocarbon-rich permeate gas stream to step (b).

### Claim 16

A process for treating a raw product stream from dehydrogenation of a light paraffin, said raw product stream comprising at least one paraffin component, one olefin component and hydrogen, comprising the sequential steps of:
(a) compressing the raw product stream to create a compressed stream having a first hydrocarbon dewpoint;
(b) partially condensing the compressed stream, including cooling and separating the compressed stream into a first hydrocarbon condensate stream and a first uncondensed gas stream;
(c) heating the first uncondensed gas stream from step (b);
(d) separating the first uncondensed gas stream from step (c) using a first membrane to remove a hydrogen-rich permeate gas stream and create a hydrocarbon-enriched residue gas stream having a first residue hydrocarbon dewpoint that is within 15° C. of the first hydrocarbon dewpoint;
(e) partially condensing the residue gas stream, including cooling and separating the residue gas stream into a second hydrocarbon condensate and a second uncondensed gas stream;
(f) recirculating at least a first portion of the second uncondensed gas stream to step (c);
(g) separating the hydrogen-rich permeate gas stream from step (d) using a pressure swing adsorption unit to remove a second hydrogen-rich permeate gas stream and create a hydrocarbon-enriched tail gas stream;
(h) recompressing and recirculating the hydrocarbon-enriched tail gas stream to step (c);
(i) separating a second portion of the second uncondensed gas stream from step (e) using a second membrane to remove a hydrocarbon-rich permeate gas stream; and
(j) recompressing and recirculating the hydrocarbon-rich permeate gas stream to step (b).

### Claim 17

A process for treating a raw product stream from dehydrogenation of a light paraffin, said raw product stream comprising at least one paraffin component, one olefin component and hydrogen, comprising the sequential steps of:
(a) compressing the raw product stream to create a compressed stream having a first hydrocarbon dewpoint;
(b) partially condensing the compressed stream, including cooling to a temperature no lower than −30° C. and separating the compressed stream into a first hydrocarbon condensate stream and a first uncondensed gas stream;
(c) heating the first uncondensed gas stream from step (b);
(d) separating the first uncondensed gas stream from step (c) using a first membrane to remove a hydrogen-rich permeate gas stream and create a hydrocarbon-enriched residue gas stream having a first residue hydrocarbon dewpoint; and
(e) partially condensing the residue gas stream, including cooling to a temperature no lower than −30° C. and separating the residue as stream into a second hydrocarbon condensate and a second uncondensed gas stream;
(f) recirculating at least a first portion of the second uncondensed gas stream to step (c)
(g) separating the hydrogen-rich permeate has stream from step (d) using a pressure swing adsorption unit to remove a second hydrogen-rich permeate gas stream and create a hydrocarbon-enriched tail gas stream;
(h) recompressing and recirculating the hydrocarbon-enriched tail gas stream to step (e);
(i) separating a second portion of the second uncondensed gas stream from step (e) using a second membrane to remove a hydrocarbon-rich permeate gas stream; and
(j) recompressing and recirculating the hydrocarbon-rich permeate gas stream to step (b).