Adsorbent bed with increased hydrothermal stability
Disclosed in certain embodiments are methods of removing water from a gas feed stream comprising hydrocarbons and water during an adsorption step of an adsorption cycle.
1 . A thermal swing adsorption method to perform hydrocarbon removal and water removal in a single adsorbent bed, the method comprising:
directing a gas feed stream having an initial water mole fraction toward the adsorbent bed, the adsorbent bed comprising:
a first adsorbent layer to remove C6+ hydrocarbons and water from the gas feed stream, wherein a weight percent (wt. %) of the first adsorbent layer with respect to the total weight of the adsorbent bed is greater than 50 wt. %, and wherein the first adsorbent layer is preferentially selective for C6+ hydrocarbons; and
a second adsorbent layer downstream from the first adsorbent layer to remove remaining water from the gas feed stream, the second adsorbent layer comprising a zeolite,
wherein a cycle time of the thermal swing adsorption method is less than or equal to about 8 hours, and
wherein, after passing through the first adsorbent layer, the gas feed stream has a reduced water mole fraction that is less than or equal to 20% of the initial water mole fraction when the gas feed stream reaches the second adsorbent layer.
2 . The thermal swing adsorption method of claim 1 , wherein the gas feed stream is a natural gas feed stream, and wherein the reduced water mole fraction is less than or equal to about 100 ppm.
3 . The thermal swing adsorption method of claim 1 , wherein the adsorbent bed further comprises a third adsorbent layer downstream from the second adsorbent layer, the third adsorbent layer comprising an amorphous silica adsorbent or an amorphous silica-alumina adsorbent.
4 . The thermal swing adsorption method of claim 1 , wherein the adsorbent bed further comprises a third adsorbent layer downstream from the second adsorbent layer, the third adsorbent layer comprising zeolite X or zeolite Y.
5 . The thermal swing adsorption method of claim 1 , wherein the adsorbent bed further comprises a third adsorbent layer downstream from the second adsorbent layer, the third adsorbent layer having a higher selectivity to n-pentane over methane.
6 . The thermal swing adsorption method of claim 1 , wherein the adsorbent bed further comprises a third adsorbent layer upstream from the first adsorbent layer, the third adsorbent layer comprising a water stable adsorbent.
7 . A thermal swing adsorption method to perform hydrocarbon removal and water removal in a single adsorbent bed during an adsorption step of an adsorption cycle, the method comprising:
directing a gas feed stream having an initial water mole fraction toward the adsorbent bed, the adsorbent bed comprising a first layer comprising one or more of amorphous silica, amorphous silica-alumina, or high-silica zeolite, and a second layer comprising zeolite, wherein a weight percent (wt. %) of the first layer with respect to the total weight of the adsorbent bed is greater than 50 wt. %, wherein the material of the first layer is preferentially selective for C6+ hydrocarbons, and wherein:
after passing through the first layer, the gas feed stream has a reduced water mole fraction that is less than or equal to 10% of the initial water mole fraction when the gas feed stream reaches the second layer,
a regeneration gas of the thermal swing adsorption method is a product gas of the thermal swing adsorption method or an external clean dry gas,
a time of an adsorption step is less than 6, 4, 2, or 1 hours,
the gas feed stream after leaving the adsorbent bed contains less than 1 ppm or less than 0.1 ppm water, and
the gas feed stream after leaving the adsorbent bed has a reduced hydrocarbon mole fraction.
8 . The thermal swing adsorption method of claim 7 , wherein the gas feed stream is a natural gas feed stream, and wherein the reduced water mole fraction is less than or equal to about 100 ppm.
9 . The thermal swing adsorption method of claim 7 , wherein the adsorbent bed further comprises a third adsorbent layer downstream from the second layer, the third adsorbent layer comprising an amorphous silica adsorbent or an amorphous silica-alumina adsorbent.
10 . The thermal swing adsorption method of claim 7 , wherein the adsorbent bed further comprises a third adsorbent layer downstream from the second layer, the third adsorbent layer comprising zeolite X or zeolite Y.
11 . The thermal swing adsorption method of claim 7 , wherein the adsorbent bed further comprises a third adsorbent layer downstream from the second layer, the third adsorbent layer having a higher selectivity to n-pentane over methane.
12 . The thermal swing adsorption method of claim 7 , wherein the adsorbent bed further comprises a third adsorbent layer upstream from the first layer, the third adsorbent layer comprising a water stable adsorbent.
13 . A method of removing water from a gas feed stream comprising hydrocarbons and water during an adsorption step of an adsorption cycle, the method comprising:
directing the gas feed stream having an initial water mole fraction toward an adsorbent bed, the adsorbent bed comprising:
a first adsorbent layer comprising an adsorbent that is preferentially selective for C6+ hydrocarbons and comprises one or more of an amorphous silica adsorbent, an amorphous silica-alumina adsorbent, or a high-silica zeolite adsorbent; and
a second adsorbent layer downstream from the first adsorbent layer to remove remaining water, the second adsorbent layer comprising a zeolite,
wherein, after passing through the first adsorbent layer, the gas feed stream has a reduced water mole fraction that is less than or equal to 10% of the initial water mole fraction when the gas feed stream reaches the second adsorbent layer, and wherein a cycle time of the adsorption cycle is less than or equal to about 8 hours.
14 . The method of claim 13 , wherein the gas feed stream is a natural gas feed stream, and wherein the reduced water mole fraction is less than or equal to about 100 ppm.
15 . The method of claim 13 , wherein the adsorbent bed further comprises a third adsorbent layer downstream from the second adsorbent layer, the third adsorbent layer comprising an amorphous silica adsorbent or an amorphous silica-alumina adsorbent.
16 . The method of claim 13 , wherein the adsorbent bed further comprises a third adsorbent layer downstream from the second adsorbent layer, the third adsorbent layer comprising zeolite X or zeolite Y.
17 . The method of claim 13 , wherein the adsorbent bed further comprises a third adsorbent layer downstream from the second adsorbent layer, the third adsorbent layer having a higher selectivity to n-pentane over methane.
18 . The method of claim 13 , wherein the adsorbent bed further comprises a third adsorbent layer upstream from the first adsorbent layer, the third adsorbent layer comprising a water stable adsorbent.