Biodiesel Production From Off-Grade Oil By Transesterification Over Differently Granulated Waste-Based CaO Catalysts

Abstract

The waste fractionated chicken eggshell catalysts were utilized and used in biodiesel production from off-grade sunflower oil. It is confirmed that thermal modification treatment was suitable for conversion of calcite form of eggshell into lime. Fractionation was carried out in the wide particle diameter range from 20 μm. to 100 μm. It is shown that the highest catalytic activity (fatty acid methyl esters content-FAME >96%) was achieved using catalyst obtained from powder faction of >45<63 μm. Important differences in catalytic activity were observed for the boundary fractions (<20 μm, >20<36 μm, and >100 μm), where catalytic activity was greatly reduced. Such behaviour could be explained by mercury intrusion porosimetry results, which indicate the existence of apparent porosity (interparticle and intraparticle) in the mentioned boundary fractions, while in the central fraction (>45<63 μm) the porosity is constant. A poorly-developed system of pores and channels leads to difficult diffusion and inadequate distribution of active centres.