Selectively Upgrading Lignin Derivatives to Carboxylates through Electrochemical Oxidative C(OH)−C Bond Cleavage by a Mn‐Doped Cobalt Oxyhydroxide Catalyst

Abstract

Oxidative cleavage of C(OH)ÀCb onds to afford carboxylates is of significant importance for the petrochemical industry and biomass valorization. Here we report an efficient electrochemical strategy for the selective upgrading of lignin derivatives to carboxylates by am anganese-doped cobalt oxyhydroxide (MnCoOOH) catalyst. Awide range of ligninderived substrates with C(OH)-C or C(O)-C units undergo efficient cleavage to corresponding carboxylates in excellent yields (80-99 %) and operational stability (200 h). Detailed investigations reveal atandem oxidation mechanism that base from the electrolyte converts secondary alcohols and their derived ketones to reactive nucleophiles,which are oxidized by electrophilic oxygen species on MnCoOOH from water.A s proof of concept, this approachwas applied to upgrade lignin derivatives with C(OH)-C or C(O)-C motifs,a chieving convergent transformation of lignin-derived mixtures to benzoate and KA oil to adipate with 91.5 %a nd 64.2 %y ields, respectively.

Alcohols electrooxidation coupled with H2 production at high current densities promoted by a cooperative catalyst

“…We sought to incorporate Au with a component that can supply electrophilic OH* for AORs. It is well-documented that transition metal oxyhydroxides (MOOHs) are capable of generating active oxygen species (OH* or O*) in an aqueous solution under certain anodic potential for oxidation of various organic substrates 23 . Hence, we expect that the MOOHs can cooperate with Au for AOR at higher potential.…”

“…Previous reports have demonstrated that Co 2+ oxidation is accompanied by the formation of electrophilic OH*, which showed catalytic activity for nucleophilic alcohols oxidation. 23 – 25 For Au/NiFeOOH (dark cyan curve in Fig. 2a ), the oxidation of Ni 2+ to Ni 3+ with possible active oxygen species generation was observed at potential (~1.47 V vs .…”

“…SCE. The resulting Co(OH) 2 nanosheet array was withdrawn and rinsed thoroughly with ethanol and distilled water 23 .…”

Electrocatalytic upcycling of polyethylene terephthalate to commodity chemicals and H2 fuel

“…Electrocatalysis can be powered by renewable energy (solar, wind, and hydro) that represents a sustainable and attractive strategy to generate clean H 2 from water at cathode and valueadded oxygenates from organic compounds at anode under mild conditions [18][19][20][21] . It has obtained great advancements in efficient and selective transformation of various organic compounds, such as simple alcohols and renewable biomass-derived oxygenates, and varieties of valuable carbonyl chemicals such as formate 22,23 , acetate 24,25 , 2,5-furandicarboxylate 26 , adipate 19 can be obtained. However, the electrocatalytic reforming of PET waste into valuable products is largely unexplored.…”

Perspectives of biomass based lignin to value added chemicals in biorefineries: challenges, extraction strategies and applications

“…The highest total potential environmental impact (PEI) per kg of lignin was observed to be 0.25 PEI per kilogram using organosolv process; the soda process was 0.02 PEI per kg; the sulfite process was 0.03 PEI per kg, and the Kraft process gave 0.09 PEI per kg of lignin. The soda process offers the lowest pollution with a PEI value of 0.02 per kg, 20 followed by the sulfite process with a value of 0.03 PEI per kg of lignin. Moreover, lignin removal using different pretreatment strategies shows several merits and demerits and their effectiveness varies according to operating conditions 27 .…”