Optimization of biodiesel production process from soybean oil using the sodium potassium tartrate doped zirconia catalyst under Microwave Chemical Reactor

• Microwave assisted transesterification was carried out for the biodiesel production.
• The sodium potassium tartrate doped zirconia new catalyst was synthesized.
• More than 94% yield of biodiesel is achieved under the optimal reaction conditions.
• Longer lifetime and maintained sustained activity after being used for four cycles.

A solid base catalyst was prepared by the sodium potassium tartrate doped zirconia and microwave assisted transesterification of soybean oil was carried out for the production of biodiesel. It was found that the catalyst of 2.0(n(Na)/n(Zr)) and calcined at 600 °C showed the optimum activity. The base strength of the catalysts was tested by the Hammett indicator method, and the results showed that the fatty acid methyl ester (FAME) yield was related to their total basicity. The catalyst was also characterized by FTIR, TGA, XRD and TEM. The experimental results showed that a 2.0:1 volume ratio of methanol to oil, 65 °C reaction temperature, 30 min reaction time and 10 wt.% catalyst amount gave the highest the yield of biodiesel. Compared to conventional method, the reaction time of the way of microwave assisted transesterification was shorter. The catalyst had longer lifetime and maintained sustained activity after being used for four cycles.