This study examines the use of tetrabutylammonium tetrafluoroborate (TBABF 4 ) as a catalyst for the depolymerization of lignin and its model compound without the addition of oxidants. The impact of electrolytes, reaction times, and solvents on the cleavage of the α-O-4 bond in lignin is investigated. The experimental setup includes specific conditions such as the use of carbon cloth (CC) as the counter electrode and a platinum plate as the working electrode. The TBABF 4 catalyst effectively cleaved the α-O-4 bond in the lignin model molecule with notable selectivity and minimal formation of by-products, resulting in a substantial conversion rate of benzyl phenyl ether (95.7 %) and a high yield of benzaldehyde dimethyl aceta (92.4 %) under specific conditions. This investigation showcases a mild electrochemical catalytic depolymerization approach for lignin model molecules at ambient temperature, thereby presenting novel avenues for further exploration in the field.
Hongxi Zhang,Zhongke Li,Xiande Yang,Meng Li,Liang Wei,Jing Yang
Lignin is anticipated to serve as a replacement for dwindling fossil fuel resources owing to its abundant sources and renewable nature. The electrochemical oxidation technique for depolymerizing lignin has garnered significant interest for its environmentally friendly and mild operating conditions. Nevertheless, the current utilization of auxiliary electrolytes, predominantly organic bases, ionic liquids, and other specialized substances, poses a constraint on the widespread adoption of this approach. Furthermore, there is a scarcity of instances where electrochemical technology has been employed to depolymerize the α-O-4 bond in lignin for the production of highly selective acetals. In this study, a sodium chloride/methanol (NaCl/MeOH) system was utilized for the direct depolymerization of the α-O-4 bond in a lignin model molecule, specifically benzyl phenyl ether (BPE). The optimal conditions resulted in a 95.2 % conversion rate of the BPE substrate and a high yield of 94.5 % for the main product, benzaldehyde dimethyl acetal(Bda). This research offers a promising approach for the electrocatalytic depolymerization of α-O-4 bonds in lignin, leading to the selective production of acetal chemicals using a common auxiliary electrolyte at room temperature in just 2 h.