Pilarisasi Bentonit dengan Al2O3 sebagai Katalis dalam Produksi Biodiesel

Abstract

Biodiesel is an alternative renewable energy source commonly utilized in diesel engines. It is synthesized through transesterification of oils or fats with alcohol, where catalysts are essential to accelerate the conversion of reactants into products. Among heterogeneous catalysts, bentonite is of particular interest due to its high montmorillonite content (85–95%), large surface area, and strong ion exchange capacity, although modifications are required to improve its catalytic performance. In this study, bentonite was modified by H₂SO₄ activation and Al₂O₃ pillarization, accompanied by ion exchange using ammonium acetate to enhance its acidity. The concentration of Al2O3 pillar (5, 10, and 15 mmol/g) was varied and its influence on structure and activity of the catalysts was evaluated. XRF analysis showed Al content increases along with the concentration of Al2O3 pillar. XRD revealed basal spacing expansion from 15.91 Å in activated bentonite to 20.2 Å, 20.54 Å, and 20.00 Å (respectively for 5, 10 and 15 mmol/g Al2O3 pillar), indicating successful intercalation of Al into the interlayer; and FTIR spectra demonstrated the disappearance of carbonate groups after acid activation, while characteristic bands of Si–O–Si, Al–OH–Al, and Si–O confirmed the structural stability of bentonite. Transesterification tests showed that Al-pillared bentonite achieved higher methyl ester conversion (81.00–82.65%) compared to activated bentonite (77.48%) and H₂SO₄ catalyst (74.65%). GC-MS analysis identified ten peaks with three dominant methyl ester compounds, namely methyl palmitate, methyl oleate, and methyl linoleate. These findings demonstrate that Al-pillared bentonite is a highly effective and stable heterogeneous catalyst, offering superior catalytic activity and biodiesel yield compared to conventional acid catalysts