Oxygen generator, heat driven, from air What chemical can be used to absorb $\ce{O2}$ from the air at normal temperature and pressure, then release the $\ce{O2}$ at normal pressure and elevated temperature, below $\pu{900 ^\circ C}$ ($\pu{1650 ^\circ F}$), that can be cycled many times?
Closest solutions I've found are silver, but its quite expensive, and absorbs oxygen slowly at normal temperature. And possibly phosphorous, but it is toxic and needs a solution.
Same question about $\ce{N2}$. I'm interested in separating $\ce{N2}$ and $\ce{O2}$ without the use of single-use chemicals or pressure pumps. Using cycled heat as a source to drive the reaction.
I expect there is some oxide that can switch oxidation levels back and forth with temperature, like hematite and magnetite.
Idea solution will be something like $\ce{CaCO3}$ is for $\ce{CO2}$. A cheap material, that quickly reacts with $\ce{CO2}$ at normal pressure and temperature. Quickly releases the $\ce{CO2}$ at elevated temperature and normal pressure.
I did check the search, it seems people usually offer to use electrolysis for this task. But water is way too costly to electrolyze in terms of power. Is there something that can be electrolyzed with $10$ times less energy, to get oxygen, that can be safely oxidized again later? Hydrogen is rather dangerous too.
The only substance that absorbs $\ce{O2}$ to form an oxide at low temperature and release it at higher temperature is mercury. This experience was done by Lavoisier, Scheele and Priestley in the years around $1780$. They were able to produce pure oxygen $\ce{O2}$ by first heating pure mercury in air at about $300$°C to slowly produce mercury oxide $\ce{HgO}$, and then overheating this oxide $\ce{HgO}$ to about $400$°C. At this temperature, $\ce{HgO}$ is decomposed into mercury and pure oxygen $\ce{O2}$. This was the way oxygen was first discovered and produced.
Unfortunately, mercury ¡s unique in this respect, and cannot be replaced by another element. No metals have been found later on to have a similar property. It is a pity : presently this experiment cannot be repeated, because of the toxicity of mercury and its compounds.
This why your dream will remain at the state of dream.