Synthesis of Boehmite Catalyst Using A Natural Soft Template for The Deoxygenation of Waste Cooking Oil Into Biofuel: Effect of Sapindus Rarak Extraction and Process Optimization

Abstrak

The development of environmentally friendly catalysts for converting waste cooking oil (WCO) into renewable energy continues to attract significant attention. In this study, mesoporous boehmite (γ-AlOOH) was synthesized from alumina derived from Lapindo mud, using Sapindus rarak extract (SRE) as a natural soft template. The saponins present in SRE play a role in regulating structure, controlling crystal growth, and enhancing porosity during the hydrothermal synthesis process. Characterization results confirmed the formation of orthorhombic γ-AlOOH, with improved physicochemical properties observed as the SRE concentration increased. The catalyst synthesized with 50 wt% SRE exhibited a surface area of 85.72 m²/g and a well-defined mesoporous structure. Nickel was subsequently incorporated into the 50 wt% SRE-derived γ-AlOOH to generate bifunctional catalytic sites, which are essential for the deoxygenation of WCO into biofuel. Process parameter optimization was conducted using response surface methodology (RSM) with a Box–Behnken design. The optimal reaction conditions were identified as 4 hours of reaction time, a temperature of 350°C, and a catalyst concentration of 5 wt%, resulting in a product yield of 78.37%. GC–MS analysis revealed that the products were predominantly composed of C15–C21 hydrocarbons, indicating biofuel formation via decarboxylation, hydrodeoxygenation, and decarbonylation pathways. This study demonstrates that γ-AlOOH synthesized using an SRE-based template is a promising and sustainable catalyst for biofuel production from WCO.

Kata kunci

• boehmite
• sapindus rarak
• WCO
• biofuel
• optimization
• deoxygenation