Catalyst for electrochemical redn. of oxygen@, esp. for fuel cell cathode - consisting of pyrolysed and partly oxidised transition metal porphyrin complex on activated charcoal

摘要

Catalyst (I) for electrochemical redn. of O2 consists of a transition metal complex (II) of a porphyrin, in pyrolysed and partly oxidised form, on activated charcoal (III). In the prepn., (II) is applied to (III), pref. by dissolving (II) in a solvent (IV), homogenising the soln. with (III) in an ultrasonic bath, adding another liq., (V) which is miscible with the solvent to ppte. (II) and ultrasonically treating to give the optimum deg. of homogenisation. (II) is then pyrolysed in the presence of a weakly oxidising gas (pref. CO2 and/or water vapour). Pref. (II) is Co(II) 5,10,15,20-tetrakis-(4-methoxyphenyl)-21H,23H-porphyrin (coTMPP), the (II):(III) (wt.) ratio is ca. 1:1, (IV) is dioxane (IVA) and (V) petroleum ether (VA); and pyrolysis is carried out for 30-60 minutes at 800-850 deg.C, pref. with a definite heat-up rate, esp. 10 deg. C/min., so that ca. 21% is lost by burning. USE/ADVANTAGE - (I) is efficient, stable and economical and is useful for O2 or air cathode for fuel cells. Pyrolysis and partial oxidn. causes a marked increase in the activity.