Magnetic reusable acid-base bifunctional Co doped Fe2O3–CaO nanocatalysts for biodiesel production from soybean oil and waste frying oil

Abstract

Biodiesel is a promising renewable liquid fuel, but the poor reusability and low FFA resistance of the transesterification catalyst is hindering its development. In this work, acid-base bi-functional Co doped Fe2O3–CaO nanocatalysts were prepared by one-pot hydrothermal followed by calcination method for biodiesel production from soybean oil and waste frying oil (WFO). The catalyst was characterized by XRD, XPS, TPD technologies and so on. The results showed that the doping of Co into the Fe2O3 lattice makes α-Fe2O3 crystal transform into γ-Fe2O3 thus the catalyst has stronger magnetic strength for magnetic separation. And the catalyst preparation conditions and reaction parameters were optimized, the results showed that under the 16:1 methanol to oil molar ratio, 3 wt% catalyst dosage, and 70 °C for 150 min, the enhanced catalytic activity and improved FFA resistance with the 98.2% and 91.5% biodiesel yield from soybean oil and WFO can be obtained, respectively. In addition, stability and reusability of the catalysts were improved and no distinct activity drop after 5 consecutive transesterification recycles. Furthermore, the functional group and composition of biodiesel were analyzed using GC-MS, ATR-FTIR and NMR techniques. And combustion dynamic characteristics were analyzed by TG, and the results demonstrate that the produced biodiesel has good combustion ability and potential application in industrial production.