Effect of NiO/SiO2 on thermo-chemical conversion of waste cooking oil to hydrocarbons.

Increase in organic waste generation, dwindling nature of global oil reserves coupled with environmental challenges caused by waste oil disposal and burning of fossil fuels necessitated the need for alternative energy resources. Waste cooking oil obtained from the frying fish outlet was analyzed for its physicochemical properties using ASTM D-975 methods. Acid and Iodine values of the oil were 30.43 ± 0.32 mgKOH/g and 57.08 ± 0.43 mgI2/100 g respectively. Thermo-chemical conversion of the oil using NiO/SiO2 at different reaction conditions (pressure, temperature, and catalyst concentration) at a residence time of 3 h yielded 33.63% hydrocarbons. Hydro-catalytic pyrolysis of waste cooking oil at 400 °C, H2 pressure of 15 bars, and catalyst to oil ratio of 0.25 g/100 cm(3) resulted in highest hydrocarbon yield (41.98%). The fuel properties of the product were: cetane number (71.16), high heating value (41.43 MJ/kg), kinematic viscosity (2.01 mm(2)/s), density (0.94 g/ml), saponification value (185.1 ± 3.96 mgKOH/g), and iodine value (20.57 ± 0.20 I2/100 g) respectively. These results show that the NiO/SiO2 could be a suitable catalyst for conversion of waste vegetable oil to hydrocarbons.