Biodiesel from rapeseed oil (Brassica napus) by supported Li2O and MgO

摘要

Vegetable oils are a vast triglyceride sourcefor biodiesel production; i.e. fatty acid methyl esters(FAME), with methanol and a catalyst via transesterification reaction. The aim of this work was to study heterogeneously catalysed biodiesel production with solid oxides such as mayenite (Ca12Al14O33) and alumina(Al2O3) as catalyst carriers using edible rapeseedoil as feedstock. These oxides were impregnated to have Li2O and MgO concentrations of 5–10 and 5–30 wt% oneach carrier, respectively. The catalysts were characterized using N2-physisorption (BET/BJH), scanning electronmicroscopy (SEM), and X-ray diffraction (XRD)analyses. The synthesized catalysts were mesoporous ranging from 119 to 401 A ° and their chemical phase composition was confirmed by the XRD. The catalyst coating (MgO/Li2O) was studied, along with the catalyst amount in the reactor and the assessment of the transesterification reaction kinetics. The reaction was studiedat 60 C, atmospheric pressure, agitation rate of180 rpm, and a reaction time of 2 h in a 6:1 molar ratioof methanol to oil. For each catalyst, loadings of 2.5, 5,and 10 wt% relative to the oil weight were evaluated.The highest biodiesel yield was obtained by 5 wt%(relative to oil weight) impregnated mayenite catalyst coated with 10 wt% of Li2O. The kinetic data fits to a pseudo-first-order model having a reaction rate constantequal to 0.045 min-1 under these mild reaction conditions.