Basicity–FAME yield correlations in metal cation modified MgAl mixed oxides for biodiesel synthesis

• Zn2 +, Co2 +, Fe3 + and La3 + modified Mg–Al oxides were synthesized.
• Basicity of catalysts improved by the metal cation modification.
• Effects of Fe3 + and La3 + on the basicity of catalysts are stronger than Zn2 + and Co2 +.
• Increasing catalyst basicity advanced FAME yield.
• La3 + modified catalyst exhibited highest activity in transesterification.

In this paper Zn2 +, Co2 +, Fe3 + and La3 + were respectively introduced into Mg3Al1 mixed oxides to prepare Mg1Zn2Al1, Mg1Co2Al1, Mg3Al0.6Fe0.4 and Mg3Al0.6La0.4 oxides by calcinations at 773 K. The XRD, XPS, BET, ICP-AES and CO2-TPD characterizations of samples exhibited that the effects of the substitution of trivalent cations (Fe3 +, La3 +) for Al3 + on the basicity of samples were stronger than the substitution of divalent cations (Zn2 +, Co2 +) for Mg2 + because of high O2 − concentration which were coincident with the FAME yield for these catalysts. La3 + modified catalyst exhibited highest activity in transesterification.

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