CO2 conversion to a harmless gas like oxygen
Submarines currently use NaOH/Ca(OH)2 to absorb CO2. They generate O2 separately either from gas tanks or by electrolysis of water. Peroxides seem attractive at first, but they are a fire hazard and you don't want fire on a submarine. British subs are using Zeolite. The role of zeolite isn't to deal with CO2, but to remove the smell of volitile organic compounds (of dirty socks, so to say). Air is first dried and purified. 

What exactly are you trying to achieve?