I don't know if there is a well defined criterion for a 'green' propellant, because apart from the common public idea of 'green' as regenerative production method, NASA seems to call propellants 'green' already if they are non-toxic non-corrosive and therefore a lot easier to handle:

https://www.nasa.gov/mission_pages/tdm/green/gpim-nears-completion.html

However, that might be publicity-related.

So LOX+RP1 or LOX+methane might be considered non-toxic and neither are their combustion products, however LOX is still rather corrosive and hazardous to handle.

The most important criteria to define a propellant as "green" are:

Of course, the propellants must meet the appropriate performance and cost criteria. The combination of LOX/Methane I am sure that it is considered as green propellants. In general, the combination of LOX/light hydrocarbons is defined as "green". An extensive study has been conducted by European Space Agency over the last 15 -20 years, and you can find more information at:

• “Green Propellants Options For Launchers, Manned Capsules And Interplanetary Missions” Dominique Valentian, et. al. 2nd International Conference on Green Propellants for Space Propulsion. Chia Laguna. Italy. June 7-8, 2004.
• “Green Propellant Propulsion Concepts For Space Transportation And Technology Development Needs” D. Haeseler, et. al. 2nd International Conference on Green Propellants for Space Propulsion. Chia Laguna. Italy. June 7-8, 2004

Also, many other "green" propellants are now investigating not only for launchers, but also for satellite propulsion systems. In the recent years you can find many scientific researches in this field. Some green propellants are: Hydrogen Peroxide for bi-propellant, monopropellant and hybrid engines, Ammonium Dinitramide to replace the Ammonium Perchlorate in solid propellants, etc.

The EU’s REACH regulation limits the use of the most common propellant in satellite propulsion, hydrazine, due to its toxicity, and this pushes the scientific community and the propulsion companies to find new "green" alternative propellants.

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