Biodiesel production using layered double hidroxides and derived mixed oxides: The role of the synthesis conditions and the catalysts properties on biodiesel conversion

The present study evaluated biodiesel production using Layered Double Hydroxides (LDHs) and derived mixed oxides as heterogeneous catalysts to analyse the relation between the physicochemical and textural properties of these materials with biodiesel yield. Experimental planning was conducted to evaluate the effect of different Mg/Al molar ratios, precipitating agents (Na2CO3 or NH3) and calcination effect on methyl ester yield. Materials were characterized by X-ray diffraction (XRD), N2-BET method, fourier-transform infrared spectra (FT-IR), point of zero charge (pHPZC) and scanning electron microscope (SEM). Biodiesel synthesis was further optimized through experimental planning considering the catalyst concentration and methanol:oil molar ratio at 4 periods of time as variables, using the material which exhibited the best performance. The material with best catalytic activity was a derived mixed oxide (calcined at 450 °C) with a Mg/Al ratio of x = 0.59, using Na2CO3 as precipitating agent. The optimized parameters for the chemical reaction were: 23:1 methanol:oil molar ratio, 3.5 wt%25 catalyst at 65 °C for 1 h, resulting in a maximum ester conversion of 98.59 wt%25. © 2019

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