Microwave-Assisted Catalytic Transesterification of Camelina Sativa Oil

Abstract

Catalytic conversion of Camelina Sativa oil to biodiesel through both conventional heating and microwave radiation was investigated. Three different types of catalysts: homogeneous catalysts (NaOH and KOH), heterogeneous metal oxide catalysts (BaO and SrO), and sol−gel derived catalysts (BaCl2/AA and SrCl2/AA) were evaluated for their efficacy in biodiesel production. The following conditions were obtained for the catalysts based on the maximum biodiesel yield: potassium hydroxide/methanol to oil ratio of 1:9, catalyst concentration of 1% (w/w), and reaction time of 60 s; sodium hydroxide/methanol to oil ratio of 1:9, catalyst concentration of 0.5 wt %, and reaction time of 60 s; barium oxide/methanol to oil ratio of 1:9, catalyst concentration of 1.5% (w/w), and reaction time of 4 min; strontium oxide/methanol to oil ratio of 1:9, catalyst concentration of 2 wt %, and reaction time of 4 min. In the case of sol−gel derived catalysts, different catalyst loading rates in the range of 1−10 mmol/g were evaluated. Low biodiesel yields of 10−25% on the sol−gel derived catalysts were observed. On the basis of energy consumptions in the transesterification processes with both conventional heating and microwave-heating methods evaluated in this study, it was estimated that the microwave-heating method consumes less than 10% of the energy to achieve the same yield as the conventional heating method. The fuel properties of camelina biodiesel produced were compared with those of the regular diesel and found to be conforming to the American Society for Testing and Materials (ASTM) standards.