Nickel-modified sulfated zirconia catalyst: Synthesis and application for transforming waste cooking oil into biogasoline via a hydrocracking process

The synthesis of a sulfated zirconia catalyst and its modification with Ni metal was carried out and applied in the hydrocracking of waste cooking oil into biogasoline. The SO₄/ZrO₂ (SZ) catalyst was synthesized via a hydrothermal process using ZrOCl₂·8H₂O as a precursor, followed by sulfation using (NH₄)₂SO₄ solution. The catalyst was calcined at a temperature of 600 °C. The obtained SZ catalyst was refluxed in aqueous solutions of Ni(NO₃)₂ with various Ni loadings (1, 2, and 3 wt% Ni), followed by reducing hydrogen gas at 400 °C to yield Ni/SZ catalysts. The impregnation of Ni on SO₄/ZrO₂ led to an increase in catalyst acidity, as well as their activity and selectivity for the hydrocracking process. Among ZrO₂ and the synthesized catalysts, 1% Ni/SZ has the highest acidity level. The hydrocracking process was performed at 450 °C. The 1% Ni/SZ catalyst was able to selectively produce the gasoline fraction, with the conversion reaching 70.28% gasoline from 80.28% for the total liquid products. As a result, the catalyst was shown to be acceptable for industrial-scale applications.