Continuous Biodiesel Production from Animal Fats and Waste Cooking Oil Using Supercritical Methanol and Nanostructured Heterogeneous Catalysts, 01-R8145Printer Friendly Version
Inclusive Dates: 04/01/10 Current
Background - In the conventional transesterification of fats/vegetable oils for biodiesel production, free fatty acids and water always present a problem, resulting in a low conversion. The objective of this study was to investigate the yield of methyl esters treated by acid-free and alkaline-free supercritical methanol with heterogeneous catalysts.
Approach - Glyceride tributyrate was used as a model compound for waste cooking oil and animal fats to study transesterification with methanol at supercritical condition (239.4 °C and 8.0 MPa) with and without solid catalysts. The transesterification reaction was studied with an automatic controlled tubular reactor in a continuous mode, as shown in Figure 1. The reactor was constructed from a 3/8-in. OD by 4-ft. long stainless tube with wall thickness of 0.049 in. (reactor volume = 47.4 mL). This system was used for the biodiesel synthesis from glyceride tributyrate, waste cooking oil, and animal fats.
Figure 1. Continuous Process Flow Diagram for Biodiesel Production
with Supercritical Methanol
Figure 1. Continuous Process Flow Diagram for Biodiesel Production with Supercritical Methanol
Accomplishments - For glyceride tributyrate, the conversion was 100 percent under supercritical methanol (SCM) condition. For waste cooking oil (WCO), the fatty acid methyl ester (FAME) yield was > 90 percent at the following reaction conditions: reaction temperatures = 300 °C and 250 °C; reaction pressures = 2,000 psi, 2,500 psi, and 3,000 psi; residence time = 18 minutes; molar ratio of methanol to oil = 40:1; and flow rate = 2.5 mL/min. At 250 °C and 2,500 psi, the WCO flow rates were increased to 4.5mL/min and 6.5mL/min, and FAME yields were > 90 percent for the flow rates. The findings demonstrated that using a supercritical methanol and solid catalytic approach, vegetable oil and its wastes could be readily used for biodiesel fuel production in a simple, cleaner, continuous, economically effective and automatic process.