Acceleration of biodiesel production from off-grade oil over waste-based CaO catalyst

Abstract

Waste-based CaO was synthesized from chicken eggshell, which calcined form (900 ºC, 5 ºC/min, 4 h) was hydrated (80 ºC, S:L=1:5, 24 h) and rehydrated/calcined (600 ºC, 5 ºC/min, 4 h). The obtained catalyst was characterized (Hg-porosimetry and TPD-CO2) and tested in biodiesel synthesis from off-grade sunflower oil by transesterification to analyse the influence of water addition on reaction intensification. Water content was varied in the range from 1 wt% to 9 wt% by weight of oil. It is shown that water addition positively affects the catalytic activity leading to a reduction in induction time and to faster achievement of the reaction equilibrium (fatty acid methyl esters content > 95%), which for a water content higher than 1 wt% is achieved in 90 min. On the other hand, the equilibrium for the reaction without water addition was achieved considerably later (after 150 min).