Sour pressure swing adsorption process

1. A method comprising:

(a) gasifying a carbonaceous feedstock to form a gasified stream comprising H2S, CO2, CO and H2;

(b) converting at least a portion of the CO in the gasified stream to CO2 and H2 using a water-gas shift reaction, resulting in a sour syngas stream;

(c) introducing the sour syngas stream into a sour pressure swing adsorption (SPSA) system having a plurality of adsorber beds;

(d) performing a cyclic PSA process using the SPSA system comprising the following steps:

(i) pressurizing a first bed of the plurality of adsorber beds to a first pressure;

(ii) feeding the sour syngas stream into an inlet end of the pressurized first bed and discharging a first gas stream from an outlet end of the first bed;

(iii) after the feeding step, introducing a rinse gas comprising at least 99 mol % N2 into the first bed, the rinse gas being from a source other than directly from another of the plurality of adsorber beds;

(e) removing a product stream from the SPSA system, the product stream having a greater concentration of H2 than the sour syngas stream and comprising at least 80 mol % H2 and at least 10 mol % N2;

(f) removing a tail gas stream from the SPSA system, the tail gas stream having a greater concentration of CO2 and H2S than the sour syngas stream; and

(g) separating the tail gas stream into an H2S-enriched stream and a H2S-depleted stream using an acid gas enrichment (AGE) system.

2. The method of claim 1 , wherein step (a) comprises gasifying a carbonaceous feedstock to form a gasified stream comprising CO, H2, at least 1000 ppm H2S, and at least 20 mol % CO2.

3. The method of claim 1 , further comprising:

(h) synthesizing a reactor product stream comprising at least 10 mol % NH3 from the product stream.

4. The method of claim 1 , wherein step (d) further comprises:

(iv) reducing the pressure of the first bed to a second pressure by placing the outlet end of the first bed in flow communication with an outlet end of a second bed of the plurality of adsorber beds while performing step (d)(iii).

5. The method of claim 4 , wherein step (d) further comprises:

(v) further reducing the pressure of the first bed to a third pressure by placing the outlet end of the first bed in flow communication with an outlet end of a third bed of the plurality of adsorber beds while performing (d)(iii).

6. The method of claim 5 , wherein step (d) further comprises:

(vi) after performing step (d)(iii) in the first bed, further reducing the pressure of the first bed to a fourth pressure by placing the outlet end of the first bed in flow communication with an outlet end of a fourth bed of the plurality of adsorber beds.

7. The method of claim 1 , wherein step (d)(iii) comprises after the feeding step, introducing a rinse gas into the inlet end of the first bed, the rinse gas being from a source other than directly from another of the plurality of adsorber beds.

8. The method of claim 1 , wherein step (d) further comprises:

(iv) after performing step (d)(iii) in the first bed, reducing the pressure of the first bed to a second pressure by placing the outlet end of the first bed in flow communication with an outlet end of a second bed of the plurality of adsorber beds.

9. The method of claim 1 , wherein step (g) comprises separating the tail gas stream into an H2S-enriched stream and a H2S-depleted stream using an acid gas enrichment (AGE) system, the H2S-enriched stream comprising at least 5 mol % H2S and no more than 95 mol % CO2.

10. The method of claim 1 , further comprising:

(k) converting at least a portion of the H2S-enriched stream to one or more selected from the group of sulfuric acid, elemental sulfur, a product derived from sulfuric acid, and a product derived from elemental sulfur using a sulfur recovery unit.

11. The method of claim 1 , wherein step (b) comprises converting at least a portion of the CO in the gasified stream to CO2 and H2 using a water-gas shift reaction, resulting in a sour syngas stream comprising at least 0.02 mol % sulfur-containing species and 25 mol % CO2.

12. The method of claim 1 , wherein step (c) comprises introducing the sour syngas stream into a sour pressure swing adsorption (SPSA) system having at least ten adsorber beds.

13. The method of claim 1 , further comprising:

(I) cooling the sour syngas stream after step (b) and before step (c).

14. The method of claim 1 , further comprising:

(m) after performing step (b) and before performing step (c), passing the sour syngas stream through a guard bed containing an adsorber adapted to remove organic tar compounds.

15. A method comprising:

(a) gasifying a carbonaceous feedstock to form a gasified stream comprising H2S, CO2, CO and H2;

(b) converting at least a portion of the CO in the gasified stream to CO2 and H2 using a water-gas shift reaction, resulting in a sour syngas stream;

(c) introducing the sour syngas stream into a sour pressure swing adsorption (SPSA) system having a plurality of adsorber beds;

(d) performing a cyclic PSA process using the SPSA system comprising the following steps:

(i) pressurizing a first bed of the plurality of adsorber beds to a first pressure;

(ii) feeding the sour syngas stream into an inlet end of the pressurized first bed and discharging a first gas stream from an outlet end of the first bed;

(iii) after the feeding step, introducing a rinse gas comprising at least 85 mol % of one or more selected from the group of CO2 and H2S into the first bed, the rinse gas being from a source other than directly from another of the plurality of adsorber beds.

(e) removing a product stream from the SPSA system, the product stream having a greater concentration of H2 than the sour syngas stream;

(f) removing a tail gas stream from the SPSA system, the tail gas stream having a greater concentration of CO2 and H2S than the sour syngas stream; and

(g) separating the tail gas stream into an H2S-enriched stream and a H2S-depleted stream using an acid gas enrichment (AGE) system.

16. The method of claim 15 , wherein step (e) comprises removing a product stream from the PSA system, the product stream comprising at least 60 mol % H2 and at least 25 mol % CO.

17. The method of claim 15 , further comprising:

(i) synthesizing a reactor product stream comprising at least 10 mol % MeOH from the product stream.

18. A method comprising:

(a) gasifying a carbonaceous feedstock to form a gasified stream comprising H2S, CO2, CO and H2;

(b) converting at least a portion of the CO in the gasified stream to CO2 and H2 using a water-gas shift reaction, resulting in a sour syngas stream;

(c) introducing the sour syngas stream into a sour pressure swing adsorption (SPSA) system having a plurality of adsorber beds;

(d) performing a cyclic PSA process using the SPSA system comprising the following steps:

(i) pressurizing a first bed of the plurality of adsorber beds to a first pressure;

(ii) feeding the sour syngas stream into an inlet end of the pressurized first bed and discharging a first gas stream from an outlet end of the first bed;

(iii) after the feeding step, introducing a rinse gas into the first bed, the rinse gas being from a source other than directly from another of the plurality of adsorber beds;

(e) removing a product stream from the SPSA system, the product stream having a greater concentration of H2 than the sour syngas stream;

(f) removing a tail gas stream from the SPSA system, the tail gas stream having a greater concentration of CO2 and H2S than the sour syngas stream;

(g) separating the tail gas stream into an H2S-enriched stream and a H2S-depleted stream using an acid gas enrichment (AGE) system; and

(h) recycling at least a portion of the H2S-depleted stream for pneumatically conveying the carbonaceous feedstock in step (a).