Pyrolysis systems and methods of generating hydrogen gas from a hydrocarbon gas

A pyrolysis system comprising:

• a solar thermal reactor having a housing configured to heat a gaseous hydrocarbon stream to its dissociation temperature yielding hydrogen gas and solid carbon;
• a supersonic turbomachine disposed in the housing, wherein the supersonic turbomachine is configured to receive the hydrogen gas and solid carbon from the solar thermal reactor and prevent the solid carbon from forming deposits on an interior wall of the housing;
• and
• a particulate separator located downstream of the supersonic turbomachine, wherein the particulate separator is configured to separate at least a majority of the solid carbon from the hydrogen gas.