Dra. Valdebenito-Escobar, Fabiola

The production of fatty acid methyl esters (FAME) from waste frying oil (WFO) was studied using fly ash as received as a heterogeneous catalyst. The fly ash used in this research had a high content of both CaO and SO3, two compounds that have been previously proposed as catalysts in FAME production. The study was carried out on the basis of a response surface methodology (RSM). The model generated by RSM predicted as optimal conditions to obtain a 100% FAME yield at a methanol-to-oil molar ratio of 3.1:1, 11.2 (wt.% based on oil weight) fly ash and a temperature of 59 C with agitation at 245 rpm and 6 h of reaction time. Additional experiments comparing anhydrous with aqueous medium showed that fly ash presented a high catalytic capacity to transform free fatty acids (FFA) into FAME through consecutive hydrolysis and esterification processes (hydroesterification) compared with that associated with the transesterification mechanism. According to the results, the fly ash used in this study would act as a multipurpose or “versatile” catalyst due to its chemical composition with constituents that act as acidic and basic catalysts, therefore, catalyzing the transesterification and hydroesterification reactions simultaneously and increasing the conversion yields of FAME.

The use of pellets as a replacement for firewood has been promoted in Chile to mitigate atmospheric pollution. However, their high demand has generated stock shortages, which has motivated the search for alternative sources of feedstock. Furthermore, invasive shrubs are a highly available biomass source for bioenergy production in central-southern Chile and may be a significant factor contributing to the spread and increasing virulence observed in wildfires across the region. This study aimed to determine the change in wildfire indicators related to the removal of invasive shrubs in selected zones in the Biobío region and to assess the physicochemical properties of the extracted biomass to develop a pellet formulation to produce a material conforming to ISO standards. The biomass management of Teline monspessulana, Ulex europaeus, and Rubus ulmifolius was evaluated using a fire simulation tool in three areas with contrasting physio-climatic conditions. Our simulation results demonstrated the effectiveness of shrub management on three critical wildfire indicators. Namely, significant decreases were observed in fireline intensity (kW/m) 58–75%, flame length (m) 0–40%, and heat per unit area (kW/m2) 86%. Furthermore, a biomass quality index (BQI) was developed based on the physicochemical parameters of the three shrubs assessed. Based on this BQI, T. monspessulana was selected as the most promising shrub biomass and was consequently used in a pilot shrub-pinewood blending to produce pellets. A blending of 20:80%m/m exhibited properties close to the ISO standard. Our results show that the management of invasive shrubs has the potential to minimize the virulence of wildfires, while the physicochemical characteristics and availability of one of the shrubs analyzed (T. monspessulana) make it a viable alternative biomass source for pellet production in the region.