Browsing by Autor "Yohannes Kiros"

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Biodiesel from rapeseed oil (Brassica napus) by supported Li2O and MgO
(Springer Nature, 2016) Jerry L. Solis; Albin Lindström Berkemar; Lucio Alejo; Yohannes Kiros
Vegetable oils are a vast triglyceride source for 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 rapeseed oil as feedstock. These oxides were impregnated to have Li2O and MgO concentrations of 5–10 and 5–30 wt% on each carrier, respectively. The catalysts were characterized using N2-physisorption (BET/BJH), scanning electron microscopy (SEM), and X-ray diffraction (XRD) analyses. The synthesized catalysts were mesoporous ranging from 119 to 401 Å 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 studied at 60 °C, atmospheric pressure, agitation rate of 180 rpm, and a reaction time of 2 h in a 6:1 molar ratio of 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 constant equal to 0.045 min−1 under these mild reaction conditions.
Calcium and tin oxides for heterogeneous transesterification of Babasssu oil (Attalea speciosa)
(Elsevier BV, 2016) Jerry L. Solis; Lucio Alejo; Yohannes Kiros
Ethanol Production from Schinus molle Essential Oil Extraction Residues
(Springer Science+Business Media, 2019) Jerry L. Solis; Robert R. Davila; Camilo Sandoval; Daniel Guzmán; Héctor Guzmán; Lucio Alejo; Yohannes Kiros
The present study determines the best conditions for the fermentation of Schinus molle drupes by the combination of different types of hydrolysis with the search for an adequate yeast strain. Schinus molle seed residues from an essential oil extraction plant (EOEP) have a high potential for ethanol production. Native yeast strains were isolated from the residues and were used to ferment the lignocellulosic residues, along with baker’s yeast (Saccharomyces cerevisiae) at 30 °C and pH 5.5 for comparison. Morphological and biochemical characterizations were carried out on the isolated yeast strains. Thermogravimetric and high-performance liquid chromatography analyses were done on the S. molle seeds (fresh and residue) to determine the ethanol production potential. The followed methodology included increasing the sugar content by hydrolysis with chemical (sulphuric acid, acetic acid, and sodium hydroxide), physical (thermal, vacuum, and ultrasound), and enzymatic treatments (amyloglucosidase and α-amylase). Once the optimum combination of yeast-hydrolysis was determined, a comparison of the greenhouse gas emissions between the original and proposed processes was done. The fermentation of the residues might replace methane from uncontrolled decomposition and reduce the solid residues in 50%/day, hence the EOEP global warming potential is reduced by 47%. The yearly income was estimated to increase by USD 2592.50 from 6302.6 L of ethanol produced from the residues.