Evaluation of heterogeneous catalyst for biodiesel production

Abstract

The transesterification reaction of local canola oil was carried out using different catalyst concentrations, methanol to oil molar ratios, and reaction temperatures. The heterogeneous catalyst evaluated in this study was strontium oxide (SrO) as compare to 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD), which is an organic base with potential for heterogenization. In addition, sodium methoxide (NaOCH₃) was used as the homogeneous reference catalyst for comparison purposes. The optimum reaction conditions for the transesterification of canola oil using these catalysts were investigated. The reaction was conducted at a fixed mixing rate of 800 rpm and under nitrogen gas atmosphere at 15 psi in a lab-scaled reactor. The progress of the reaction was monitored by ¹H NMR spectroscopy. The experimental results demonstrated that the optimum conditions for transesterification reaction of canola oil with methanol using NaOCH₃ are 0.59 wt% catalyst concentration, 6:1 methanol/oil molar ratio, 90 ℃ for a biodiesel yield of higher than 90% after 20 min of reaction time. In the case to TBD, the optimum reaction conditions are 2.29 wt% catalyst concentration, 3.5:1 methanol/oil molar, ratio, 60 ℃ for a biodiesel yield of more than 90 ℃ after 20 min of reaction time. While the highest reaction yield was reached using 5 wt% SrO, 6:1 methanol/oil molar ratio, 90 ℃ which renders a biodiesel yield of more than 94% after 10 min of reaction time. The catalyst combination effect was also studied. The results indicated that the combination of catalyst with egg shell and lobster shell does improve the biodiesel yield.