LAUSR

Abstract Circularity in the resources usage is one of the current challenges in the development of our civilization. At the same time, there is an imperative need for cleaner and competitive energy sources, alternatives to those of fossil origin. In this context, the present work aimed to optimize a continuous process for fatty acid methyl esters (FAME) production using residual resources, namely waste cooking oil (WCO) and pelletized biomass fly ash as catalyst. A fixed bed tubular continuous reactor was designed and built. The pelletized catalyst performance was assessed in the reaction system, which was fed with a mixture of refined palm oil (RPO), WCO and methanol at 60 °C. The effect of three operating variables (residence time, WCO/RPO mass ratio and methanol/oil molar ratio) on FAME concentration was studied, using experimental the Box-Benhken design and the Response Surface Methodology (RSM). The maximum FAME concentration achieved was c.a. 89.7% under the following operating conditions: 124 min of residence time, 74.6 wt% WCO/RPO and 12:1 methanol/oil molar ratio. The catalyst kept stable over the 32 h of continuous operation, without noticeable deactivation. Thus, the pelletization of an industrial biomass fly ash, with bifunctional catalytic properties, allowed its application to the FAME production in a continuous regime, with high performance even when high percentages of WCO were used as feedstock.