Selective hydrogenolysis of catechyl lignin into propenylcatechol over an atomically dispersed ruthenium catalyst

Abstract

C-lignin is a homo-biopolymer, being made up of caffeyl alcohol exclusively. There is significant interest in developing efficient and selective catalyst for depolymerization of C-lignin, as it represents an ideal feedstock for producing catechol derivatives. Here we report an atomically dispersed Ru catalyst, which can serve as an efficient catalyst for the hydrogenolysis of C-lignin via the cleavage of C−O bonds in benzodioxane linkages, giving catechols in high yields with TONs up to 345. A unique selectivity to propenylcatechol (77%) is obtained, which is otherwise hard to achieve, because this catalyst is capable of hydrogenolysis rather than hydrogenation. This catalyst also demonstrates good reusability in C-lignin depolymerization. Detailed investigations by model compounds concluded that the pathways involving dehydration and/or dehydrogenation reactions are incompatible routes; we deduced that caffeyl alcohol generated via concurrent C−O bonds cleavage of benzodioxane unit may act as an intermediate in the C-lignin hydrogenolysis. Current demonstration validates that atomically dispersed metals can not only catalyze small molecules reactions, but also drive the transformation of abundant and renewable biopolymer.

Understanding the Effect of Second Metal on CoM (M = Ni, Cu, Zn) Metal–Organic Frameworks for Electrocatalytic Oxygen Evolution Reaction

“…Facing the carbon emission issue, hydrogen can be used as not only a kind of clean and efficient fuel, but also crucial feed for carbon recycling reaction (e.g., CO 2 hydrogenation to chemicals, depolymerization of polyethylene). [1][2][3][4][5] In conjunction with electricity generated from renewable energy source such as wind and tidal power, electrochemical water splitting has been considered as one of the most appealing approaches for production of carbon-free hydrogen. However, the total efficiency of electrochemical water splitting is greatly limited by the oxygen evolution reaction (OER) at spectroscopic studies and theoretical calculations, the markedly different OER activity of these MOFs is attributed to the electronic structure of Co and thus the adsorption of reaction intermediate on Co site.…”

Targeted Substituted-Phenol Production by Strategic Hydrogenolysis of Sugar-Cane Lignin

“…When Yoshikawa et al investigated a two-step process of phenol production from lignin, they reported that iron oxide favoured catechol and methoxyphenol conversion to molecules like phenols, cresols and alkylphenols [47]. Many reactions like hydrogenolysis, hydrodeoxygenation, hydrogenation, dehydration, decarboxylation, and decarbonylation [43,48] can occur in lignin depolymerisation and the final product depends upon the type of catalyst used.…”

One-pot production of phenazine from lignin-derived catechol

“…They can be directly produced via thermochemical conversion of lignin 13 or by depolymerizing catechyl lignin (C-lignin, a type of lignin that solely comprises catechyl units instead of G/S units). 27–30 Hydrolyzing the methoxy group in lignin-derived guaiacyl monomers also produces catechols. 31,32 Compared with phenolic monomers, the upgrading of catechyl monomers has been less studied.…”