Methods for preparing hydrogen and solid carbon from a gaseous hydrocarbon source using microwaves and/or radio waves
Provided are methods for preparing hydrogen and solid carbon. Illustrative methods comprise providing a feedstock comprising gaseous hydrocarbons to a microwave-inert reaction vessel and/or a radio wave-inert reaction vessel. The reaction vessel has solid carbon, about 0% water and about 0% molecular oxygen inside the reaction vessel and the carbon inside the reaction vessel is operable to heat the feedstock comprising gaseous hydrocarbons. The carbon is then exposed to microwaves and/or radio waves until the solid carbon is at a temperature of at least 1200 Kelvin, thereby forming hydrogen and solid carbon. Once formed, the hydrogen and solid carbon are separated.
1. A method for preparing hydrogen and solid carbon, the method comprising:
a) providing a reaction vessel so that the reaction vessel has 0 wt % water and 0 wt % molecular oxygen inside the reaction vessel;
b) providing a feedstock comprising gaseous hydrocarbons to the reaction vessel, the reaction vessel having a starting solid carbon, 0 wt % water and 0 wt % molecular oxygen inside the reaction vessel, and the starting solid carbon being operable to heat the feedstock comprising gaseous hydrocarbons;
c) exposing the starting solid carbon in the reaction vessel to microwaves until the starting solid carbon is at a temperature of at least 1200 Kelvin, wherein the starting solid carbon is the primary microwave susceptor;
d) breaking carbon-hydrogen bonds of the gaseous hydrocarbons of the feedstock by heat transfer between the starting solid carbon and the gaseous hydrocarbons, thereby forming hydrogen and a prepared solid carbon in the reaction vessel; and
e) separating the hydrogen and the prepared solid carbon,
wherein the reaction vessel is microwave inert; and
wherein the method is conducted in a single-reactor system, wherein the single reactor is the reaction vessel.
2. The method of claim 1 wherein the reaction vessel comprises microwave transparent materials.
3. The method of claim 1 wherein the reaction vessel comprises microwave reflective materials.
4. The method of claim 1 wherein the reaction vessel is made from quartz and a high temperature metal alloy.
5. The method of claim 1 wherein the feedstock is natural gas.
6. The method of claim 1 wherein the feedstock is a gaseous feedstock.
7. The method of claim 1 wherein the feedstock is substantially devoid of non-hydrocarbon gases.
8. The method of claim 1 wherein the feedstock contains 0 wt % of an inert gas.
9. The method of claim 1 wherein the feedstock consists essentially of gaseous hydrocarbons.
10. The method of claim 1 wherein the prepared solid carbon is solid carbon produced by pyrolysis of gaseous hydrocarbons.
11. The method of claim 1 wherein, after exposing the starting solid carbon in the reaction vessel to microwaves, the starting solid carbon is at a temperature in the range of from 1200 Kelvin to about 2000 Kelvin or the starting solid carbon and the prepared solid carbon is at a temperature range of from 1200 Kelvin to about 2000 Kelvin.
12. The method of claim 1 wherein, after exposing the starting solid carbon in the reaction vessel to microwaves, the starting solid carbon is at a temperature in the range of from about 1300 Kelvin to about 1900 Kelvin, or the starting solid carbon and the prepared solid carbon is at a temperature in the range of from about 1300 Kelvin to about 1900 Kelvin.
13. The method of claim 1 wherein, after exposing the starting solid carbon in the reaction vessel to microwaves, the starting solid carbon is at a temperature in the range of from about 1400 Kelvin to about 1800 Kelvin, or the starting solid carbon and the prepared solid carbon is at a temperature in the range of from about 1400 Kelvin to about 1800 Kelvin.
14. The method of claim 1 wherein, after exposing the starting solid carbon in the reaction vessel to microwaves, the starting solid carbon is at a temperature in the range of from about 1500 Kelvin to about 1700 Kelvin, or the starting solid carbon and the prepared solid carbon is at a temperature in the range of from about 1500 Kelvin to about 1700 Kelvin.
15. The method of claim 1 wherein, after exposing the starting solid carbon in the reaction vessel to microwaves, the starting solid carbon is at a temperature of about 1600 Kelvin, or the starting solid carbon and the prepared solid carbon is at a temperature of about 1600 Kelvin.
16. The method of claim 1 wherein the method does not use a catalyst.
17. The method of claim 1 wherein the hydrogen and the prepared solid carbon are produced in the absence of plasma formation by the microwaves.
18. The method of claim 1 wherein the starting solid carbon is free of metal impurities and oxygen-containing species.
19. The method of claim 1 wherein the hydrogen and the prepared solid carbon are formed without substantial formation of carbon monoxide.
20. The method of claim 1 wherein the feedstock has less than or equal to 2 wt % water.