Biodiesel 6 Catalyst activity 4 Scanning electron microscopy 4 Temperature programmed desorption 4 Biodiesel production 3 Carbon dioxide 3 Esterification 3 Palm oil 3 Reusability 3 Transesterification 3 X ray diffraction 3 Catalysts 2 Esters 2 Fatty acids 2 Fourier transform infrared spectroscopy 2 Gravimetric analysis 2 Heterogeneous catalyst 2 Heterogeneous solid acid catalyst 2 Infrared spectroscopy 2 Lime 2 Molar ratio 2 Nanocatalysts 2 Palm fatty acid distillate 2 Physico-chemical characterization 2 QD Chemistry 2 TP Chemical technology 2 Thermal gravimetric analyses (TGA) 2 Thermogravimetric analysis 2 Transesterification process 2 Transesterification reaction 2