A circular carbon process involves: a) reacting hydrogen and carbon monoxide to produce methane and water, b) decomposing methane into carbon and hydrogen, and c) using carbon as reducing agent and/or using carbon in a carbon-containing material as reducing agent, in a chemical process to produce carbon monoxide and a reduced substance. The methane produced in a) is used in b), the carbon produced in b) is used in c), and carbon monoxide produced in c) is used in a).

A circular carbon process involves: a) reacting hydrogen and carbon monoxide to produce methane and water, b) decomposing methane into carbon and hydrogen, and c) using carbon as reducing agent and/or using carbon in a carbon-containing material as reducing agent, in a chemical process to produce carbon monoxide and a reduced substance. The methane produced in a) is used in b), the carbon produced in b) is used in c), and carbon monoxide produced in c) is used in a).

Generating methane by adding hydrogen to CO.sub.2 in exhaust gas discharged a from cement production facility or CO.sub.2 that is separated and recovered from the exhaust gas, and using the methane as an alternative fuel to fossil fuel such as coal, petroleum, natural gas and the like, by methanation of CO.sub.2 in the exhaust gas from the cement production facility that includes exhaust gas originated from lime stone not from the fossil oil and effectively utilizing it, it is possible to reduce usage of the fossil fuel, suppress CO.sub.2 originated from energy, and improve an effect of reducing greenhouse gas.

Generating methane by adding hydrogen to CO.sub.2 in exhaust gas discharged a from cement production facility or CO.sub.2 that is separated and recovered from the exhaust gas, and using the methane as an alternative fuel to fossil fuel such as coal, petroleum, natural gas and the like, by methanation of CO.sub.2 in the exhaust gas from the cement production facility that includes exhaust gas originated from lime stone not from the fossil oil and effectively utilizing it, it is possible to reduce usage of the fossil fuel, suppress CO.sub.2 originated from energy, and improve an effect of reducing greenhouse gas.

A hydrogenolysis bimetallic supported catalyst comprising a first metal, a second metal, and a zeolitic support; wherein the first metal and the second metal are different; and wherein the first metal and the second metal can each independently be selected from the group consisting of iridium (Ir), platinum (Pt), rhodium (Rh), ruthenium (Ru), palladium (Pd), molybdenum (Mo), tungsten (W), nickel (Ni), and cobalt (Co).

A hydrogenolysis bimetallic supported catalyst comprising a first metal, a second metal, and a zeolitic support; wherein the first metal and the second metal are different; and wherein the first metal and the second metal can each independently be selected from the group consisting of iridium (Ir), platinum (Pt), rhodium (Rh), ruthenium (Ru), palladium (Pd), molybdenum (Mo), tungsten (W), nickel (Ni), and cobalt (Co).

A hydrogenolysis bimetallic supported catalyst comprising a first metal, a second metal, and a zeolitic support; wherein the first metal and the second metal are different; and wherein the first metal and the second metal can each independently be selected from the group consisting of iridium (Ir), platinum (Pt), rhodium (Rh), ruthenium (Ru), palladium (Pd), molybdenum (Mo), tungsten (W), nickel (Ni), and cobalt (Co).

A method is disclosed for rejuvenation a cobalt Fischer Tropsch catalyst used in a Fischer Tropsch process operating in recycle mode. The method permits the use of specific inert gases to adjust the mole weight of the gas so that the recycle compressor designed for normal steady state operation can also be used in the method. Hydrogen from a membrane permeate stream is added to the reactor loop at a temperature between 300 F and 400 F and the carbon oxides are reacted out to purify the hydrogen. This stream is continuously recycled and the temperature is raised to between 425 F and 500 F and held at the final temperature for between 4 hours and 48 hours. The cobalt Fischer Tropsch catalyst is effectively rejuvenated in-situ by the method.

A method is disclosed for rejuvenation a cobalt Fischer Tropsch catalyst used in a Fischer Tropsch process operating in recycle mode. The method permits the use of specific inert gases to adjust the mole weight of the gas so that the recycle compressor designed for normal steady state operation can also be used in the method. Hydrogen from a membrane permeate stream is added to the reactor loop at a temperature between 300 F and 400 F and the carbon oxides are reacted out to purify the hydrogen. This stream is continuously recycled and the temperature is raised to between 425 F and 500 F and held at the final temperature for between 4 hours and 48 hours. The cobalt Fischer Tropsch catalyst is effectively rejuvenated in-situ by the method.

One variation of a method includes: ingesting an air sample captured during an air capture period at a target location for collection of a first mixture including carbon dioxide and a first concentration of impurities; conveying the first mixture through a liquefaction unit to generate a second mixture including carbon dioxide and a second concentration of impurities less than the first concentration of impurities; in a methanation reactor, mixing the second mixture with hydrogen to generate a first hydrocarbon mixture comprising a third concentration of impurities comprising nitrogen, carbon dioxide, and hydrogen; conveying the first hydrocarbon mixture through a separation unit configured to remove impurities from the first hydrocarbon mixture to generate a second hydrocarbon a fourth concentration of impurities less than the third concentration of impurities; and depositing the second hydrocarbon mixture in a diamond reactor containing a set of diamond seeds to generate a first set of diamonds.