Isomerization of n-butane over Fe,Mn-promoted sulfated zirconia: catalytic activity and surface features of the catalyst

摘要

The catalytic properties of Fe,Mn-promoted sulfated zirconia catalysts have been tested as a function of: (i) the temperature of the preliminary calcination step; (ii) the conditions of the catalyst activation step; (iii) the temperature of the catalytic reaction. In was observed that the promotion effect is mainly ascribable to the Fe component, and requires: (i) a preliminary calcination at T_calc>850 K, most likely to liberate from sulfates as much as possible of the surface Fe component; (ii) an activation cycle (at T_act≈700 K) in strictly oxidizing conditions, in order to have as much as possible of the surface Fe~III component in a reducible form; (III) reaction temperatures close to ambient temperature, in order to prevent the predominance of poisoning reactions and to avoid an extensive reduction of the Fe component.