Removal of contaminants from gas using zeolite SSZ-36, zeolite SSZ-39, or zeolite SSZ-45

Patent metadata

Field	Value
Publication number	US-10092875-B2
Application number	US-201715408533-A
Country	US
Kind code	B2
Filing date	Jan 18, 2017
Priority date	Jan 18, 2017
Publication date	Oct 9, 2018
Grant date	Oct 9, 2018

Abstract

We provide a method for removing contaminants from a gas, comprising: alternating input of the gas between two or more beds of adsorbent particles that comprise zeolite SSZ-36, zeolite SSZ-39, or zeolite SSZ-45; wherein the gas contacts one of the beds during an adsorption and a tail gas is simultaneously vented from another of the beds by desorption; wherein a contacting pressure is from about 345 kPa to about 6895 kPa and produces a product gas containing no greater than about 2 mol % carbon dioxide, at least about 10 wppm water, at least about 65 mol % of methane recovered from the feed gas, and at least about 25 mol % of ethane recovered from the feed gas; and wherein the tail gas is vented from the feed end of the beds. We also provide a method for removing a contaminant from a gas, wherein the gas contains hydrogen sulfide.

First claim

It is claimed:

1. A method for removing a contaminant comprising a water from a feed gas stream that includes the contaminant, a methane and an ethane, comprising:
alternating an input of the feed gas stream between an at least two beds of adsorbent particles made from a homogeneous mixture, wherein the adsorbent particles comprise a zeolite SSZ-36, a zeolite SSZ-39, a zeolite SSZ-45, or a combination thereof;
wherein the feed gas stream contacts one of the at least two beds at a given time by an adsorption step and a tail gas stream is simultaneously vented from another of the at least two beds by a desorption step;
wherein a contacting in the one of the at least two beds occurs at a feed pressure of from about 345 kPa to about 6895 kPa for a sufficient time to preferentially adsorb the contaminant from the feed gas stream and thereby producing a product gas stream containing no greater than about 2 mol % carbon dioxide, at least about 10 wppm of the water, at least about 65 mol % of the methane recovered from the feed gas stream, and at least about 25 mol % of the ethane recovered from the feed gas stream; and
wherein the feed gas stream is input at a feed end of each of the at least two beds, the product gas stream is removed from a product end of each of the at least two beds, and the tail gas stream is vented from the feed end of the at least two beds.

2. The method of claim 1 , wherein the water is adsorbed by the at least two beds of the adsorbent particles and a CO 2 adsorption capacity of the one or more adsorbent particles is lowered by less than 30 mol %.

3. The method of claim 1 , wherein the at least two beds of the adsorbent particles are four beds of the adsorbent particles and the product gas stream contains at least about 80 mol % of the methane recovered from the feed gas stream and at least about 40 mol % of the ethane recovered from the feed gas stream.

4. The method of claim 1 , wherein the feed gas stream comprises the carbon dioxide, from 20 to 5000 wppm of the water, and from 0 to 1000 wppm hydrogen sulfide.

5. The method of claim 1 , wherein the feed gas stream comprises an acid gas selected from the group consisting of the carbon dioxide, a hydrogen sulfide, a carbonyl sulfide, and combinations thereof.

6. The method of claim 1 , wherein the zeolite SSZ-36 or the zeolite SSZ-39 has a Si:Al mole ratio of from 5 to 100.

7. The method of claim 1 , wherein the zeolite SSZ-45 has a Si:Al mole ratio from 101 to 400.

8. The method of claim 1 , wherein the feed gas stream has a flow rate of from 1 to 100 MMSCFD during the adsorption and the adsorption occurs at an adsorption-temperature from 20 to 80° C.

9. The method of claim 1 , wherein the product gas stream comprises at least about 20 wppm of the water, at least about 95 mol % total-methane, and at least about 3 mol % total-ethane.

10. The method of claim 1 , wherein the product gas stream contains no greater than about 50 wppm hydrogen sulfide.

11. The method of claim 1 , wherein the product gas stream contains no greater than about 4 wppm hydrogen sulfide and no greater than about 2000 wppm of the water.

12. The method of claim 1 , wherein the zeolite SSZ-36 has a cation as a framework ion and the cation is selected from the group consisting of a sodium, a calcium, a potassium, a lithium, a magnesium, and a barium.

13. The method of claim 12 , wherein the cation is the sodium.

14. The method of claim 1 , wherein the zeolite SSZ-39 has a cation as a framework ion and the cation is selected from the group consisting of a sodium, a calcium, a potassium, a lithium, a magnesium, and a barium.

15. The method of claim 14 , wherein the cation is the sodium.

16. The method of claim 1 , wherein the zeolite SSZ-45 has a cation as a framework ion and the cation is selected from the group consisting of a sodium, a calcium, a potassium, a lithium, a magnesium, and a barium.

17. The method of claim 1 , wherein the method utilizes two beds of the one or more adsorbent particles, and further comprising:
a. following the adsorption step in one of the two beds and a simultaneous desorption step in the other of the two beds, equalizing a pressure of the one of the two beds and the other of the two beds through the product end of each of the one of the two beds and the other of the two beds at an end of the adsorption and the simultaneous desorption step; and
b. re-pressurizing the other of the two beds having just completed the simultaneous desorption step by sending a slipstream of the product gas stream through the product end of the other of the two beds having just completed the simultaneous desorption step.

18. The method of claim 1 , wherein the at least two beds of the one or more adsorbent particles are four beds; further comprising:
a. following a first adsorption step in a first bed of the four beds, a first equalization step occurs wherein the first bed is allowed to pressure equalize with a second bed of the four beds having a lower pressure than the first bed through a first line connecting the product end of the first bed and the product end of the second bed;
b. following the first equalization step, lowering the feed pressure in the first bed and passing a gas from the first bed to a third bed of the four beds through a second line connecting the product end of the first bed and the product end of the third bed in a providing purge step such that the third bed of the four beds is purged;
c. following the providing purge step, a second equalization step occurs wherein the first bed is allowed to pressure equalize with the third bed of the four beds having the lower pressure than the first bed through a third line connecting the product end of the first bed and the product end of the third bed;
d. following the second equalization step, depressurizing a first adsorbent bed to the feed pressure from about 6.89 kPa to about 138 kPa through the feed end of the first adsorbent bed in a blowdown step comprising either:
i) allowing the gas in the first adsorbent bed to vent to a purge tank; or
ii) using a vacuum pump to lower the feed pressure of the first adsorbent bed;

e. following the blowdown step, the first bed is purged in a purging step wherein the gas is provided to the first bed through the product end of the first bed from a fourth bed of the four beds while the first bed is at the feed pressure from about 6.89 kPa to about 138 kPa and gas is purged through the feed end of the first bed;
f. following the purging step, a third equalization step occurs wherein the first bed is allowed to pressure equalize with the fourth bed having a higher pressure than the first bed through a fourth line connecting the product end of the first bed and the product end of the fourth bed;
g. following the third equalization step, a fourth equalization step occurs wherein the first bed is allowed to equalize with the second bed having the higher pressure than the first bed through a fifth line connecting the product end of the first bed and the product end of the second bed;
h. following the fourth equalization step, passing a slipstream of a product-gas or a stream of a storage gas from a storage tank through the product end of the first bed to repressurize the first bed to an adsorption-step-pressure in a repressurization step; and
i. following the repressurization step, operating the first bed in an independent adsorption step for a sufficient period of time for the third bed and the fourth bed to be pressure equalized and the second bed to be depressurized prior to beginning a second adsorptio

Assignees

• Chevron Usa Inc

Inventors

• Thompson Joshua Allen
• Davis Tracy Margaret
• Xie Dan
• Zones Stacey Ian

Classifications

• B01D2257/308

  Carbonoxysulfide COS · CPC title

• B01D2257/304

  Hydrogen sulfide · CPC title

• B01D2259/414

  using different types of adsorbents · CPC title

• B01D2259/40045

  with two sub-steps · CPC title

• B01D53/0423

  Beds in columns · CPC title