M. Fleischer et al., Selective gas detection with high-temperature operated metal oxides using catalytic filters, SENS ACTU-B, 69(1-2), 2000, pp. 205-210
Metal oxide gas sensors in general, show high sensitivity but poor selectiv
ity if pure sensor materials are used. The performance in terms of reproduc
ibility may be enhanced by using very stable materials, which may be operat
ed at quite high temperature but this does not help in the problem of selec
tivity. This paper discusses the use of gas pretreatment using filters oper
ated at elevated temperatures to overcome this problem for special applicat
ions. Three different types of gas filters are discussed: a physical filter
which is permeated by hydrogen only, a catalyst filter which removes distu
rbing solvent vapours by oxidation, and a gas conversion filter which ensur
es a defined NO/NO2 equilibrium. These filters relate to the applications o
f selective indoor CH4, H-2, and automotive exhaust gas nitrogen oxide dete
ction. (C) 2000 Elsevier Science S.A. All rights reserved.