CaO–TiO2 bimetallic mixed oxide applied to the production of biodiesel from cotton oil (Gossypium hisutum): monitoring of the procedure by TGA

This study investigates the use of CaO–TiO 2 mixed oxides as solid base catalysts to produce biodiesel from cotton oil ( Gossypium hirsutism ). These CaO–TiO 2 mixed-oxide catalysts were prepared in different molar proportions of Ca:Ti (0.75Ca:0.25Ti, 1Ca:1Ti e 0.25Ca:0.75Ti) and characterized by X-ray diffraction, Fourier transform infrared spectroscopy (FTIR), thermogravimetry (TGA), Raman spectroscopy, scanning electron microscopy (SEM) coupled with energy-dispersive X-ray analysis, and Brunauer–Emmett–Teller surface area analysis. The effects of reaction parameters such as the methanol/oil molar ratio, the amount of catalyst amount, and the reaction temperature were also investigated. The process was evaluated by TGA and confirmed by FTIR and GC/MS. The catalysts obtained were tested in the following reaction parameters: 20:1 methanol:oil molar ratio; 10% of catalyst amount; and 60 °C temperature for 5 h. The best catalyst was determined to be 0.25Ca–0.75Ti (calcined at 800 °C), considering its catalytic and anti-leeching abilities, because it obtained the highest yield (92.2%) without leaching calcium. Therefore, CaO–TiO 2 catalysts have the potential to be used in biodiesel products.