A. Maltha et al., MANGANESE OXIDES AS CATALYSTS FOR THE SELECTIVE REDUCTION OF NITROBENZENE TO NITROSOBENZENE, Journal of catalysis, 149(2), 1994, pp. 364-374
The activity and selectivity of various MnOx catalysts for the selecti
ve reduction of nitrobenzene to nitrosobenzene have been studied, meas
uring the rate in a continuous flow reactor. Characterisation of the c
atalysts has been performed with XRD, IR, UV/VIS, EM, and TPR. It appe
ared that the steady-state catalyst is in all cases the spinel Mn3O4 i
n a slightly reduced form. Without the addition of an external reducta
nt to the feed, nitrobenzene was not only reduced but also oxidised, w
hich created oxygen vacancies in the catalyst surface. Addition of an
external reductant did not cause a change in the amount of nitrosobenz
ene formed, but the concentration of side products, like aniline and d
imerisation products, increased. It is suggested that the selective re
duction of nitrobenzene with the catalyst Mn3O4 runs by the Mars and V
an Krevelen mechanism. (C) 1994 Academic Press, Inc.