Bimetallic Au-Pd Supported on Activated Carbon for the Catalytic Valorization of Lignin

Lignocellulosic biomass is a source of molecules for the further production chemicals and biomaterials. Lignin is the second most abundant natural polymer, making up about 25 % of biomass. Three types of substituted phenols, which can be obtained from lignin depolymerization, compose its structure (Fig. 1) [1]. Their conversion into high-value products on large scale requires the optimization of catalytic processes [2]. In particular, heterogeneous catalytic oxidation reactions allow the production of platform aromatic compounds with easy product separation [3]. Selected model compounds, such as Veratryl alcohol (VA), are very useful to carry out fine chemical production studies. This work reported the oxidation of VA to Veratraldehyde (VAL) by Au-Pd supported on activated carbon (AC), with the aim to disclose the synergistic effect of bimetallic structures converting such substrate into the corresponding aldehyde (Fig. 2). The activity of the same catalysts in benzyl alcohol (BA) oxidation was used as benchmark in order to highlight the influence of the reactant [4]. Perfumery, agrochemical, and pharmaceutical industries make extensive use of VAL. It is mostly present in perfume compounds and formulations, flavoring for food, odorants, and pharmaceutical intermediates [5]. Considering that the traditional synthesis requires harmful alkylating agents, hazardous reagents and produces large amount of waste [6], improving the efficiency of the catalytic processes is even more advantageous per se in addition to be used as model reaction for lignin derivative valorization.