Preparation and characterization of hydrotalcite-like materials from flyash for transesterification

In the present study, attempts were made to synthesize Mg–Al hydrotalcite-like materials with bifunctional properties from flyash and flyash-based zeolite by coprecipitation method. The synthesized hydrotalcite and their corresponding Mg–Al mixed oxides obtained after calcination were characterized for their structural, compositional, thermal, and morphological properties. The synthesized hydrotalcite had Mg/Al ranging from 1.3 to 2.3. The activity of the synthesized catalyst was estimated in transesterification of mustard oil, and the effects of reaction time, catalyst concentration, and methanol-to-oil molar ratio on biodiesel production were also investigated. A maximum yield of 93.4 % was obtained with methanol-to-oil molar ratio of 12:1, 7 wt% catalyst concentration for 6 h of reaction at 65 °C. The average value of activation energy of biodiesel in the conversion range of 0.2 < X < 0.9 was 130.5 kJ mol⁻¹. This study showed the potential application of flyash and its use in modified Mg–Al hydrotalcite materials as heterogeneous catalysts in biodiesel production.