Experimental investigation on biodiesel production through simultaneous esterification and transesterification using mixed rare earth catalysts

In this study, biodiesel production through simultaneous esterification and transesterification of palm oil with 10 wt% of oleic acid using the mixed rare earth catalyst was investigated. The mixed rare earth catalysts were prepared via the co-precipitation method. The effects of the precipitating parameters such as temperature, stirring speed and pH on the physicochemical and morphology of the catalysts were studied. All catalysts were thoroughly characterized using X-ray diffraction (XRD), scanning electron microscopy-energy dispersive spectrometer (SEM-EDS), fourier transform-infrared spectroscopy (FTIR), N2adsorption/desorption, CO2 temperature programmed desorption (CO2-TPD) and NH3 temperature programmed desorption. (NH3-TPD). The results indicated that the mixed rare earth catalyst prepared under the precipitation conditions: at pH 9, a stirring of 400 rpm and temperature of 30 °C showed the highest catalytic of 90% FAME content. High surface area of the catalyst, a significant larger amount of Ce and La contents in the catalyst and an appropriate amount of acid and basic sites on the catalyst led to the high catalytic activity. The catalyst could also accelerate the initial reaction rate to achieve the high FAME content of 50% within 30 min

Effect of Dynamic Recrystallization on the Transformed Ferrite Microstructures in HSLA Steel

The flow stress behavior of high-strength low-alloy (HSLA) steel at different true strains was studied using a hot compression test. The effect of dynamic recrystallization (DRX) on the transformed ferrite microstructures was investigated with electron backscatter diffraction (EBSD). The EBSD analysis indicated that the fraction of high-angle grain boundaries (HAGBs) and DRX increased with increasing true strain. The low-angle grain boundaries (LAGBs) were gradually transformed into HAGBs with increasing DRX degree. When the true strain was increased to 0.916, the fraction of HAGBs increased to 85% and the fraction of DRX increased to 80.3%. The relatively high fraction of HAGBs was related to the complete DRX. The dislocations and substructures in the tested steel at different true strains were characterized by transmission electron microscopy (TEM). TEM observation shows that the nucleation of the dynamically recrystallized grains occurred by the bulging of the original grain boundaries. The DRX nucleation mechanism of the HSLA steel is the strain-induced grain boundary migration mechanism

Effect of deformation parameters on microstructural evolution during hot compression of Nb–V–Mo microalloyed steel

The flow behavior of Nb–V–Mo microalloyed steel at different deformation parameters was investigated using isothermal compression tests. The microstructures of the specimens after deformation were observed through the use of a metallographic microscope. The results indicated that the deformation temperature had a significant effect on the grain size of the deformed specimen and the average size of grains increases with corresponding increase in temperature in the range of 800 °C–1100 °C. The dislocations and substructures of the specimens after deformation were characterized using TEM. The bulged grain boundary was observed through TEM when the specimen was deformed at 1100 °C and 1 s ^−1 . The effect of the strain rate on the dynamic recrystallization behavior was investigated using electron backscatter diffraction (EBSD). The EBSD results indicated that the fraction of low-angle grain boundaries decreased with a corresponding decrease in strain rate, and the average sub-boundary misorientation increased with a decreasing strain rate. The continuous dynamic recrystallization mechanism was determined through EBSD analysis