# US 7,608,133 B2 · Lithium-exchanged faujasites for carbon dioxide removal

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- Number: US 7,608,133 B2
- Document ID: US7608133B2
- Status: Granted
- Kind: B2
- Application number: 11/383,589
- Filed: 2006-05-16
- Published: 2007-08-30
- Granted: 2009-10-27
- Earliest claimed: 2006-02-27
- Assignees: Honeywell International Inc.
- Inventors: Stephen F. Yates; Allen A. MacKnight
- Web page: https://patentgrep.com/patent/US7608133B2

## CPC

- B01D 53/02: by adsorption, e.g. preparative gas chromatography {(solid sorbent compositions B01J20/00, preparation of inorganic compounds or elements C01)}
- B01J 20/186: {Chemical treatments in view of modifying the properties of the sieve, e.g. increasing the stability or the activity, also decreasing the activity}
- B01D 2253/108: Zeolites
- B01D 2257/504: Carbon dioxide
- Y02C 20/40: of CO2
- 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)
- B01J: CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- Y02C: CAPTURE, STORAGE, SEQUESTRATION OR DISPOSAL OF GREENHOUSE GASES [GHG]

## Abstract

A process for removal of carbon dioxide from air using lithium-exchanged X-zeolites at low carbon dioxide partial pressures is provided. The process is particularly useful in applications where fresh air is not available and exhaled air needs to be recycled. An apparatus for carrying out the process is also provided.

## Claims

### Claim 1

A process for removing carbon dioxide from a gas comprising the steps of:
feeding a stream of gas through an adsorbent bed at a carbon dioxide partial pressure of less than about 10 torr;
adsorbing carbon dioxide from the gas stream to yield a carbon-dioxide depleted gas, the adsorbent bed comprising a lithium-exchanged X-zeolite; and
regenerating the adsorbent bed, after it is substantially saturated, with a pressure swing desorption from about 1×10−6 torr to about 1 torr.

### Claim 2 (depends on 1)

The process of claim 1 wherein the partial pressure is less than about 1 torr.

### Claim 3 (depends on 1)

The process of claim 1 wherein the lithium-exchanged X-zeolite comprises lithium-exchanged X-zeolite beads.

### Claim 4 (depends on 1)

The process of claim 1 wherein the lithium-exchanged X-zeolite comprises a lithium-exchanged X-zeolite polymer composite.

### Claim 5 (depends on 1)

The process of claim 1 wherein the stream of gas is fed through the adsorbent bed at a linear velocity of from about 1.95 cm/sec to about 7.80 cm/sec.

### Claim 6 (depends on 1)

The process of claim 1 further comprising the step of feeding the gas through a desiccant bed prior to feeding the gas through the adsorbent bed.

### Claim 7 (depends on 1)

The process of claim 1 wherein the adsorbent bed is regenerated by a combination of pressure swing desorption and temperature swing desorption.

### Claim 8 (depends on 1)

The process of claim 1 wherein the gas is exhaled air and the carbon-dioxide depleted gas is used as inhaled air.

### Claim 9

A process for removing carbon dioxide from air comprising the steps of:
feeding a stream of air, at approximately ambient pressure, through an adsorbent bed at a carbon dioxide partial pressure from about 0.1 torr to 1 torr to yield a carbon dioxide depleted gas, the adsorbent bed comprising a lithium-exchanged X-zeolite; and
regenerating the adsorbent bed when it is saturated.

### Claim 10 (depends on 9)

The process of claim 9 further comprising the step of feeding the air through a desiccant bed prior to feeding the air through the adsorbent bed.

### Claim 11 (depends on 9)

The process of claim 9 wherein the lithium-exchanged X-zeolite comprises a lithium-exchanged X-zeolite polymer composite.

### Claim 12 (depends on 9)

The process of claim 9 wherein the adsorbent bed is regenerated by a combination of temperature swing desorption and pressure swing desorption.

### Claim 13 (depends on 12)

The process of claim 12 wherein the temperature swing desorption is from about 50° C. to about 100° C.

### Claim 14 (depends on 12)

The process of claim 12 wherein the pressure swing desorption is from about 1×10−6 torr to about 1 torr.

### Claim 15 (depends on 9)

The process of claim 9 wherein the step of regenerating the adsorbent bed when it is saturated comprises exposing the adsorbent bed to outer-space.

### Claim 16 (depends on 9)

The process of claim 9 wherein the air is exhaled air.

### Claim 17

A process for removing carbon dioxide from air comprising the steps of:
feeding the air through a desiccant bed to yield a dry air;
feeding the air through an adsorbent bed at a carbon-dioxide partial pressure of from about 0.1 torr to about 1 torr to yield carbon dioxide depleted air, the adsorbent bed comprising a lithium-exchanged X-zeolite; and
regenerating the adsorbent bed, after it is substantially saturated, with a pressure swing desorption from about 1×10−6 torr to about 1 torr.