Upgrading pyrolysis carbon
Methods are provided for upgrading of pyrolysis carbon in order to allow for conversion of the pyrolysis carbon into higher value products. Instead of attempting to convert methane into a high value carbon product (such as carbon nanotubes) and H 2 in a single reaction step, pyrolysis conditions can be used to form H 2 and pyrolysis carbon. The pyrolysis carbon can then be treated in order to convert the pyrolysis carbon (H to C atomic ratio of less than 0.20) into a product with a higher hydrogen content (H to C atomic ratio of 0.25-0.9 or 2.0-7.0 wt % H). The treatment can correspond to exposing the pyrolysis carbon with hydrogen in the presence of a catalyst, exposing the pyrolysis carbon to conditions for alkylation, or a sequential combination thereof. This can convert the pyrolysis carbon into heavy hydrocarbon products that are resin-like solids at room temperature.
1. A method for upgrading pyrolysis carbon, comprising:
combining particles of pyrolysis carbon with a solvent to form a slurry, the pyrolysis carbon comprising an atomic hydrogen to carbon ratio of from 0.04 to 0.20; and
exposing the particles of pyrolysis carbon to hydrogen in the presence of a catalyst under slurry hydroprocessing conditions to form an upgraded carbon product comprising an atomic hydrogen to carbon ratio of 0.25 or more; wherein the pyrolysis carbon comprises carbon-based substances formed during pyrolysis of methane to form hydrogen.
2. The method of claim 1 , wherein the upgraded carbon product comprises an atomic hydrogen to carbon ratio of 0.25 to 0.9, or wherein the upgraded carbon product comprises a hydrogen content of 2.0 wt % to 5.0 wt %, or a combination thereof.
3. The method of claim 1 , wherein the pyrolysis carbon comprises an atomic hydrogen to carbon ratio of 0.13 or less.
4. The method of claim 1 , wherein the particles of pyrolysis carbon comprise an average particle size of 1.0 cm or less, or wherein the particles of pyrolysis carbon comprise a maximum particle size of 1.0 cm or less, or a combination thereof.
5. The method of claim 1 , wherein the upgraded carbon product comprises a softening point of 200° C. or higher.
6. The method of claim 1 , the method further comprising physically processing a pyrolysis carbon feed to form the particles of pyrolysis carbon.
7. The method of claim 1 , the method further comprising incorporating the upgraded carbon product into a structural material.
8. The method of claim 1 , wherein the particles of pyrolysis carbon comprise a sulfur content of 0.5 wt % or less.
9. The method of claim 1 , wherein the particles of pyrolysis carbon comprise a sulfur content of 0.01 wt % to 0.2 wt %.
10. The method of claim 1 , wherein the particles of pyrolysis carbon comprise a transition metals content of 0.1 wt % to 10 wt %, or wherein the particles of pyrolysis carbon comprise an alkali metals content of 0.2 wt % to 2.0 wt %, or a combination thereof.
11. The method of claim 1 , wherein the particles of pyrolysis carbon comprise pyrolysis carbon derived from pyrolysis of hydrocarbons in a molten media environment, or wherein the particles of pyrolysis carbon comprise pyrolysis carbon derived from pyrolysis of hydrocarbons in at least one of a thermal plasma environment and a microwave plasma environment, or a combination thereof.
12. The method of claim 1 , wherein the upgraded carbon product comprises a solid.
13. The method of claim 1 , wherein a weight percent of hydrogen in the upgraded carbon product is greater than a weight percent of hydrogen in the pyrolysis carbon by 6.0 wt % or less.
14. The method of claim 1 , wherein the slurry hydroprocessing conditions comprise a temperature of 300°° C. to 480° C. and a hydrogen partial pressure of 6.9 MPa to 23.4 MPa, or wherein the slurry comprises 5.0 vol % to 80 vol % of particles of pyrolysis carbon, relative to a total volume of the slurry, or a combination thereof.
15. The method of claim 1 , further comprising exposing at least a portion of the upgraded carbon product to
a) a quaternary base and optionally at least one of a metal hydroxide and a metal alkoxide under phase transfer catalysis conditions in the presence of a protic solvent;
b) an alkyl halide and a metal halide at a temperature of 20° C. to 200° C. and a pressure of 100 kPa-a to 5.0 MPa-a in the presence of a second solvent, the metal halide having the stoichiometry MX n where M is a metal, X is a halogen, and n is an integer between 2 and 6; or
c) a combination of a) and b),
to form a sequentially upgraded carbon product comprising an atomic hydrogen to carbon ratio of 0.25 or more.
16. The method of claim 15 , wherein the slurry hydroprocessing conditions produce a slurry hydroprocessing effluent comprising the upgraded carbon product, and wherein exposing at least a portion of the upgraded carbon product comprises exposing 50 vol % or more of the slurry hydroprocessing effluent, the second solvent comprising at least a portion of the solvent.
17. The method of claim 15 , wherein the slurry hydroprocessing conditions produce a slurry hydroprocessing effluent comprising the upgraded carbon product, the method further comprising:
separating the at least a portion of the upgraded carbon product from the slurry hydroprocessing effluent; and
mixing the upgraded carbon product with the protic solvent or the second solvent prior to the exposing the at least a portion of the upgraded carbon product.
18. The method of claim 15 , wherein the sequentially upgraded carbon product comprises a softening point of 200° C. or higher.
19. The method of claim 15 , The method of claim 1 , wherein a weight percent of hydrogen in the upgraded carbon product is greater than a weight percent of hydrogen in the pyrolysis carbon by 6.0 wt % or less.
20. A method for upgrading pyrolysis carbon, comprising:
combining particles of pyrolysis carbon with a solvent to form a slurry, the pyrolysis carbon comprising an atomic ratio of hydrogen to carbon of from 0.04 to 0.20; and
exposing the particles of pyrolysis carbon to
a) a quaternary base and optionally at least one of a metal hydroxide and a metal alkoxide under phase transfer catalysis conditions, the solvent comprising a protic solvent;
b) an alkyl halide and a metal halide at a temperature of 20° C. to 200° C. and a pressure of 100 kPa-a to 5.0 MPa-a, the metal halide having the stoichiometry MX n where M is a metal, X is a halogen, and n is an integer between 2 and 6; or
c) a combination of a) and b),
to form an upgraded carbon product comprising an atomic hydrogen to carbon ratio of 0.25 or more; wherein the pyrolysis carbon comprises carbon-based substances formed during pyrolysis of methane to form hydrogen.
21. The method of claim 20 , wherein the phase transfer catalysis conditions comprise a temperature of 20° C. to 200° C. and a pressure of 100 kPa-a to 5.0 MPa-a.
22. The method of claim 20 , wherein the particles of pyrolysis carbon are exposed to an alkyl halide and a metal halide, and wherein the solvent comprises an alkyl-substituted aromatic.
23. The method of claim 20 , i) wherein the particles of pyrolysis carbon comprise a transition metals content of 0.1 wt % to 10 wt %, ii) wherein the particles of pyrolysis carbon comprise an alkali metals content of 0.2 wt % to 2.0 wt %, iii) wherein a total weight of metals in the upgraded carbon product is lower than a total weight of metals in the pyrolysis carbon by 50 wt % or less relative to the total weight of metals in the pyrolysis carbon, or iv) a combination thereof.
24. The method of claim 20 , wherein a weight percent of hydrogen in the upgraded carbon product is greater than a weight percent of hydrogen in the pyrolysis carbon by 6.0 wt % or less.