MgNiAlLa Oxide Solid Base for Biodiesel Synthesis.

MgNiAlLa-LDHs (layered double hydroxides) with different La content were synthesized by co-precipitation method and calcined to MgNiAlLa-oxides, and used as heterogeneous base catalysts for transesterification of palm oil with methanol to produce biodiesel, compared to the oxides without Ni (MgAlLaoxide) or La (MgNiAl-oxide). All were characterized by X-ray powder diffraction (XRD) and N2 adsorption-desorption. Metal contents were determined using inductively coupled plasma (ICP) emission spectrometry. Basicity was determined by titration method. Catalytic order of the oxides is: MgNiAlLa (b, high La) > MgAlLa > MgNiAlLa(a, low La) > MgNiAl, related to their basicity. Various parameters influencing the reaction were investigated: methanol/oil molar ratio, temperature and amount of catalyst. The optimum condition for transesterification over the MgNiAlLa(b)-oxide catalyst is: methanol/oil molar ratio of 15, 4 wt% catalyst, 3 h reaction time and at 95 °C yielding 93 %FAME. The catalyst can be reused 4 times and regenerated by washing/calcination to regain its activity. [ABSTRACT FROM AUTHOR]