Conversion of Neem Oil (Azadirachta indica) to Biodiesel over SBA-15 Supported Sulphated Zirconia Catalysts

Currently, conversion of a non-edible oil to biodiesel by transesterification is commercially an important alternative to use of edible oils. Designing heterogeneous catalysts for transesterification of non-edible oils to biodiesel is continuously attracting researchers, as the catalysts are recoverable and recyclable. In this context, SBA-15 supported sulphated zirconia (SO 4 2− /ZrO 2 (5,10,15 wt%)/SBA-15) was synthesised and characterised by common analytical techniques. The TEM images showed the orderly arrangement of mesopores in SBA-15 and uniform distribution of SO 4 2− /ZrO 2 on it. Pyridine adsorbed FT-IR exhibited both the Bronsted and Lewis acid sites. For the first time, the catalytic activity of SO 4 2− /ZrO 2 (5,10,15 wt%)/SBA-15 was studied for the conversion of neem ( Azadirachta indica ) oil to biodiesel with methanol at 50,60,70,80,90 and 100 °C in a Teflon-lined stainless steel autoclave. The oil conversion was 98% at 80 °C in 180 min with 100% selectivity to biodiesel. This temperature was lower than the previously reported values with other catalysts. When the reaction was carried out with neem oil and other alcohols, such as ethanol, propanol, butanol and isopropanol, under similar conditions, the conversion significantly decreased in the order methanol > ethanol > propanol > butanol > isopropanol. Similarly, other oils such as jatropha, mustard, castor, mahua, pongamia, and waste cooking oil were also examined for transesterification, and the results discussed. The catalyst maintained activity for six cycles for neem oil. So, from this study, it is recommended that the present catalyst can be a good choice for the commercial production of biodiesel from neem oil. Graphical Abstract