Investigating biodiesel production from Chicken fat oil using bi-functional catalysts and microbubble mediated mass transfer

Abstract

Biodiesel production has been limited by slow kinetics of acid catalyzed esterification, downstream product separation before transesterification and expensive feedstock. Bi-functional catalysts can carry out esterification and transesterification simultaneously. However, an energy efficient method is still required to enhance the kinetics of esterification. Similarly, the thermodynamic equilibrium hindering the overall conversion of the esterification needs to be manipulated to increase the overall conversion of the process. The manuscript proposes a new bi-functional catalyst, 7 % Sr/ZrO2, along with microbubble mediated injection of alcohol. The conversion of free fatty acids (FFA) and Triglycerides by bi-functional catalysts was compared with three naturally occurring bi-functional catalysts- Zwitterions. Chicken fat oil was chosen as the feedstock. Preliminary experiments were conducted to select alcohol. Experiments were designed using Response Surface Methodology. The current study shows that the use of heterogeneous catalysts and CFO as a feedstock has lucrative potentials. The rate of reaction and conversion of the process are further increased by overcoming the thermodynamic equilibrium using microbubble mediated mass transfer increasing process feasibility. Response Surface Methodology (RSM) was used to design the experiments. 7 % Sr/ZrO2 was found to give significantly higher conversion of triglycerides as compared with the Zwitterions. However, conversion of FFA using Aspartic acid was almost similar to 7 % Sr/ZrO2. For triglycerides and FFA, the conversion of CFO at optimize conditions using (Molar ratio = 1: 14, temperature 70 °C, and catalyst loading 1 %) was 75 % and 57 %, as compared with aspartic acid (61 % and 63 %), arginine (58 % and 73 %), and isoleucine (54 % and 39 %) respectively. Detailed comparison between other reported bi-functional catalysts showed that 7 %Sr/ZrO2 yielded a high conversion in significantly less time. The higher performance can be attributed to the use of microbubble mediated mass transfer. The results indicate that integration of microbubble mediated mass transfer and a bi-functional catalyst can accelerate the industrial reactive separations comprising biodiesel production.