Study by high-throughput experimentation of the effect of the pretreatment and precursors on the catalytic activity of tungstated zirconia catalysts

Abstract

Abstract High-throughput experimentation (HTE) was used for the synthesis, characterization and catalytic evaluation of tungstated zirconia (WZ) materials doped with manganese. A library with three series of MnOy–WOx–ZrO2 catalysts was prepared by different methods (surfactant-assisted coprecipitation and impregnation), using different precursors and pretreatments (washing and/or aging). These materials were characterized by XRD, Raman and MET (HRTEM and EDS). Different nanostructures were observed depending on the synthesis method. Highly dispersed WO3 catalysts calcined at 800 °C were obtained by coprecipitation method, while the impregnation method brings the segregation of both, the monoclinic WO3 and ZrO2 phases. The catalytic activity of the Pt-promoted MnOy–WOx–ZrO2 catalysts (0.3 wt.% Pt) was evaluated in the n-hexane hydroisomerization reaction. Although, in the coprecipitated catalysts similar WOx nanostructures were observed, the catalytic activity mainly depends on the zirconia precursor, as well as aging and washing pretreatments, following the order: ZrOCl2 (coprecipitation) > ZrO(NO3)2 (coprecipitation) ≫ Zr(OH)4 (impregnation). The catalysts with highest activity were pretreated by washing and aging.