Particle size distribution and morphological changes in activated carbon‐metal oxide hybrid catalysts prepared under different heating conditions

Abstract

[EN] In catalysis processes, activated carbon (AC) andmetal oxides (MOs) are widely used either as catalysts or as catalyst supports because of their unique properties. A combination of AC and a MO in a single hybrid material entails changes not only in the composition, microstructure and texture but also in the morphology, whichmay largely influence the catalytic behaviour of the resulting product. Thiswork isaimedat investigating the modifications in themorphology and particle size distribution (PSD) for AC-MO hybrid catalysts as a result of their preparation under markedly different heating conditions. From a commercial AC and six MO (Al2O3, Fe2O3, ZnO, SnO2, TiO2 andWO3) precursors, two series of such catalysts are prepared by wet impregnation, oven-drying at 120ºC, and subsequent heat treatment at 200ºC or 850ºC in inert atmosphere. The resulting samples are characterized in terms of theirmorphology andPSDby scanning electronmicroscopy and ImageJ processing program. Obtained results indicate that the morphology, PSD and degree of dispersion of the supported catalysts are strongly dependent both on the MO precursor and the heat treatment temperature. With the temperature rise, trends are towards the improvement of crystallinity, the broadening of the PSD and the increase in the average particle size, thus suggesting the involvement of sinteringmechanisms. Such effects aremore pronounced for the Fe, Sn andWcatalysts due to the reduction of the corresponding MOs by AC during the heat treatment at 850ºC.