Catalytic Behaviour of MnZrOx System for Heterogenous Biodiesel Production

Manganese/zirconium mixed oxides catalysts (MnZrOx), characterized by high Mn loading (up to 50%), along with high specific surface area, have been investigated in the transesterification reaction of sunflower oil. Catalysts were found to be very active by operating at low catalyst/oil ratio (1 wt.%). The high activity was justified on the basis of both the marked basic character of such systems and their high porosity that favours the accessibility of active sites. The calcination at high temperature (600°C) negatively reflects on the catalyst textural properties, drastically reducing the total surface area and consequently the catalytic activity. On the other side, such thermal treatment allows the obtainment of a macroporous structure with enhanced active sites accessibility, making Mn0.8Zr0.2_600 the most active sample per unit of surface area.