(569fa) Using Mgal-Layered Double Hydroxides Modified with SiO2 for the Electrocatalytic Conversion of Waste Cooking Oil into Biodiesel

In this study, an electrocatalytic conversion system was investigated for biodiesel production from waste cooking oil (WCO). The system employs simultaneous esterification and transesterification, utilizing MgAl-layered double hydroxides modified with SiO₂. A proposed mechanism outlines the (trans)esterification process, generating CH₃O^– and OH^– on the MgAl-LDH@SiO₂ as the semiconductor heterogeneous catalyst. The addition of SiO₂ improved the catalyst's basicity and increased the exposure of oxygen atoms on its surface, thereby facilitating the formation of methoxides for nucleophilic attacks on the triglyceride's carbonyl. Moreover, MgAl-LDH@SiO₂, acting as an electrocatalyst, reduces the initial potential rate and enhances the transport of charge carriers. The results demonstrate a 98.4% FAME yield achieved at higher water content from WCO after 90 minutes of reaction at 25℃, utilizing 2 wt% of the MgAl-LDH@SiO₂ catalyst and methanol to WCO (M:WCO) molar ratio of 6:1. MgAl-LDH@SiO₂ also proves effective for WCO containing 3.3 wt% of free fatty acid (FFA) and exhibits high stability for WCO (trans)esterification after 5 runs. The electrocatalytic conversion system has the potential to drive innovation in the development of a novel process for converting waste oils with high levels of FFA and water into second-generation biodiesel.