Hydrotalcite base catalysts for biodiesel production

Abstract

In this work, solid base catalysts were synthesized. They were MgAI and MgGa hydrotalcites, calcined hydrotalcites, metal loaded calcined hydrotalcites and rehydrated hydrotalcites. Different group I metals were loaded in different weight percentage. The synthesized catalysts were characterized by XRD, IR, BET, SEM and basicity was measured. To compare their catalytic activities, tributyrin was used as a model compound for transesterification with methanol at a fixed reaction condition: catalyst 1.5wt%, termperature 60 degree celsius, time 3 h, molar ratio of methanol to tributyrin 30:1. GC was used to analyse the product, methyl butanoate. The results showed that the rehydrated hydrotalcites gave higher %conversion of tributyrin than the calcined ones. When the metal was loaded on the calcined hydrotalcites, %conversion of tributyrin was increased. The calcined MgAI hydrotalcite which was loaded with 1.5%K was chosen to catalyze the transesterification of refined palm oil with methanol. The reaction condition was optimized and was found at a temperature of 100 degree celsius, the molar ratio of methanol to oil of 45:1, reaction time 9 h, catalyst 7.5wt%, High product yield (85.6%) and ester content (93.7%) were obtained. These catalysts can be regenerated (by calcinations and reloading metal) with slight decrease in activity.