BIOMASS PYROLYSIS INTEGRATED WITH BIO-REDUCTION OF METAL ORES, HYDROGEN PRODUCTION, AND/OR ACTIVATED-CARBON PRODUCTION
Improved processes and systems are disclosed for producing renewable hydrogen suitable for reducing metal ores, as well as for producing activated carbon. Some variations provide a process comprising: pyrolyzing biomass to generate a biogenic reagent comprising carbon and a pyrolysis off-gas; converting the pyrolysis off-gas to additional reducing gas and/or heat; reacting at least some of the biogenic reagent with a reactant to generate a reducing gas; and chemically reducing a metal oxide in the presence of the reducing gas. Some variations provide a process for producing renewable hydrogen by biomass pyrolysis to generate a biogenic reagent, conversion of the biogenic reagent to a reducing gas, and separation and recovery of hydrogen from the reducing gas. A reducing-gas composition for reducing a metal oxide is provided, comprising renewable hydrogen according to a hydrogen-isotope analysis. Reacted biogenic reagent may also be recovered as an activated carbon product. Many variations are disclosed.
1 . An activated carbon product produced by a process comprising:
(a) providing a biomass feedstock;
(b) pyrolyzing the biomass feedstock, thereby generating a biogenic reagent, wherein the biogenic reagent comprises carbon, and a pyrolysis off-gas;
(c) optionally, oxidizing the pyrolysis off-gas, thereby generating heat;
(d) reacting the biogenic reagent with a selected reactant, thereby generating a reducing gas;
(e) optionally, chemically reducing a selected metal oxide in the presence of the reducing gas from step (d), thereby generating a reduced form of the selected metal oxide; and
(f) recovering the biogenic reagent continuously or periodically during step (d), or ultimately after step (d), thereby generating a recovered biogenic reagent, wherein the recovered biogenic reagent is activated carbon.
2 . The activated carbon product of claim 1 , wherein step (b) is conducted at a pyrolysis temperature of at least about 250° C. to at most about 1250° C.\
3 . The activated carbon product of claim 1 , wherein the pyrolysis temperature is at least about 300° C. to at most about 700° C.
4 . The activated carbon product of claim 1 , wherein step (b) is conducted for a pyrolysis time of at least about 10 seconds to at most about 24 hours.
5 . The activated carbon product of claim 1 , wherein step (d) is conducted at a reaction temperature of at least about 300° C. to at most about 1200° C.
6 . The activated carbon product of claim 5 , wherein the reaction temperature is at least about 400° C. to at most about 1000° C.
7 . The activated carbon product of claim 1 , wherein step (d) is conducted for a reaction time of at least about 1 second to at most about 1 hour.
8 . The activated carbon product of claim 1 , wherein the biogenic reagent comprises at least about 50 wt % carbon.
9 . The activated carbon product of claim 1 , wherein the biogenic reagent comprises at least about 75 wt % carbon.
10 . The activated carbon product of claim 1 , wherein the biogenic reagent comprises at least about 50 wt % fixed carbon.
11 . The activated carbon product of claim 1 , wherein the biogenic reagent comprises at least about 75 wt % fixed carbon.
12 . The activated carbon product of claim 1 , wherein the reducing gas comprises at least about 10 mol % hydrogen.
13 . The activated carbon product of claim 1 , wherein the reducing gas comprises at least about 25 mol % hydrogen.
14 . The activated carbon product of claim 1 , wherein the reducing gas comprises at least about 10 mol % the carbon monoxide.
15 . The activated carbon product of claim 1 , wherein the reducing gas comprises at least about 25 mol % the carbon monoxide.
16 . The activated carbon product of claim 1 , wherein the process further comprises increasing hydrogen content of the reducing gas via the water-gas shift reaction.
17 . The activated carbon product of claim 1 , wherein the selected reactant in step (d) is water.
18 . The activated carbon product of claim 1 , wherein the selected reactant in step (d) is oxygen, and wherein the oxygen is comprised within air, pure oxygen, enriched oxygen, ozone, or a combination thereof.
19 . The activated carbon product of claim 1 , wherein the selected reactant in step (d) comprises a combination of water and oxygen.
20 . The activated carbon product of claim 1 , wherein at least about 10 wt % of the biogenic reagent generated in step (b) is recovered as the activated carbon in step (f).
21 . The activated carbon product of claim 1 , wherein at least about 50 wt % of the biogenic reagent generated in step (b) is recovered as the activated carbon in step (f).
22 . The activated carbon product of claim 1 , wherein at least about 90 wt % of the biogenic reagent generated in step (b) is recovered as the activated carbon in step (f).
23 . The activated carbon product of claim 1 , wherein at least about 50 wt % of the fixed carbon within the biogenic reagent generated in step (b) is recovered as the activated carbon in step (f).
24 . The activated carbon product of claim 1 , wherein at least about 90 wt % of the fixed carbon within the biogenic reagent generated in step (b) is recovered as the activated carbon in step (f).
25 . The activated carbon product of claim 1 , wherein essentially all of the fixed carbon within the biogenic reagent generated in step (b) is recovered as the activated carbon in step (f).
26 . The activated carbon product of claim 1 , wherein the activated carbon is characterized by an Iodine Number of at least about 500.
27 . The activated carbon product of claim 1 , wherein the activated carbon is characterized by an Iodine Number of at least about 1000.
28 . The activated carbon product of claim 1 , wherein the activated carbon is characterized by an Iodine Number of at least about 1500.
29 . The activated carbon product of claim 1 , wherein the activated carbon is characterized by an Iodine Number of at least about 2000.
30 . The activated carbon product of claim 1 , wherein the activated carbon is characterized by a renewable carbon content of at least about 90% as determined from a measurement of the 14 C/ 12 C isotopic ratio of the activated carbon.
31 . The activated carbon product of claim 1 , wherein the activated carbon is characterized as consisting essentially of renewable activated carbon as determined from a measurement of the 14 C/ 12 C isotopic ratio of the activated carbon.