Application of Zeolite-X as a Nanostructured Catalyst for Biodiesel Production from a Ternary Oil Blend

Abstract

The rising demand for sustainable and eco-friendly energy sources has intensified research into biodiesel production using efficient catalysts and diverse feedstocks. This study examines the application of zeolite-X, a nanostructured catalyst, for the production of biodiesel from a ternary blend of neem seed oil, palm kernel oil, and waste cooking oil. Zeolite-X was characterized through Scanning Electron Microscopy (SEM) and Fourier-Transform Infrared Spectroscopy (FTIR) to validate its structure and properties. The esterification process was conducted to lower the free fatty acid content to below 1% to prevent soap formation. Biodiesel was synthesized from this mixture via the transesterification process using methanol, catalyzed by zeolite-X. The process was optimized through response surface methodology (central composite design). The physicochemical parameters of the ternary oil blend are as follows: acid value, 17.43 mgKOH/g; free fatty acid, 8.715%; viscosity, 69.8 mPa.s; and saponification value of 135.329 mgKOH/g. The optimal parameters are at a methanol-to-oil ratio of 5.5:1, a reaction temperature of 60°C, a reaction duration of 105 minutes, and a catalyst loading of 7%. Gas Chromatography-Mass Spectrometry (GC-MS) was employed to analyse the fatty acid composition of the optimized biodiesel. The biodiesel's key physicochemical properties were evaluated and found to comply with or approximate ASTM standards: density of 0.8712 g/ml (ASTM standard: 0.88 g/ml), the kinematic viscosity of 4.27 mm²/s (ASTM range: 1.9-6.0 mm²/s), acid value of 0.947 mgKOH/g, free fatty acid content of 0.4735% (ASTM limit: <0.5%), flashpoint of 129°C (ASTM range: 100-170°C), and calorific value of 40.41 MJ/kg (ASTM standard: >35 MJ/kg). This study illustrates that Zeolite-X serves as an efficient nanocatalyst for biodiesel synthesis, presenting a viable pathway for sustainable energy derived from blended renewable oils with favourable fuel characteristics.