Preparation and characterization of ordered mesoporous Mg–Al–Co hydrotalcite based catalyst for decarboxylation of jatropha oil

Abstract

This paper reported preparation of novel order mesoporous Mg–Al–Co hydrotalcite based catalysts through sol–gel procedure using precursors such Mg(NO3)2, Al(NO3)3 and Co(NO3)2 and Na2CO3. The catalyst also contained both acidity and basicity being very convenient for decarboxylation process of vegetable oil to green hydrocarbons. The alkaline media was maintained at pH 10 during the processes. Molar ratio of metal cations and temperature of the sol–gel processes were investigated for their effect in the mesoporous structure formation. The results showed that the procedure should be established at 70 °C with the molar Mg/Al/Co ratio of 1/5/0.2. Acidity and basicity of the mesoporous hydrotalcite based catalyst were demonstrated for their co-existence. The as-synthesized material at the suitable conditions was used as catalyst for decarboxylation of jatropha oil to obtain green hydrocarbons mainly belonging to diesel fraction. The decarboxylation was carried out at 400 °C for 3 h in closed auto-pressurized reactor exhibiting a yield of diesel involving hydrocarbons of over 70% after distillation and analysis. The result also confirmed that the acidity and basicity greatly accelerated the activity of the catalyst. Some techniques were used to characterizing the catalyst including XRD, SEM, TEM, TGA, NH3-TPD, CO2-TPD and BET, and GC–MS was also used to analyze the main product composition.