State-of-the-art catalytic hydrogenolysis of lignin for the production of aromatic chemicals

Abstract

Catalytic hydrogenolysis of lignin is overviewed, concerning the cleavage of typical inter-unit linkages and the production of aromatic chemicals.

Chemicals from Lignin: A Review of Catalytic Conversion Involving Hydrogen

“…Aside from the metal hydrogenation sites, acidic supports with strong oxygen affinity are also critical for the removal of phenolic hydroxy groups . In this respect, high‐valence and strong Lewis‐acidity metals, such as Ti, Mo, Nb, Re, and W, are desirable candidates for the oxophilic sites .…”

Across the Board: Mark Mascal on the Challenges of Lignin Biorefining

“…The first impulse of most researchers undertaking a lignin project is to “divide and conquer”, by first separating out the individual lignin subunits and then converting them into various products. Efforts in this area have received much attention . However, a potentially more constructive approach would be to embrace the complexity of lignin, rather than fight it.…”

“…The first impulse of most researchers undertaking al ignin project is to "divide and conquer",b yf irst separating out the individual lignin subunits and then converting them into various products.E fforts in this area have received much attention. [4,5] However,apotentially more constructivea pproachw ould be to embrace the complexity of lignin, rather than fight it. One example of this is the work of Rinaldi and co-workers, who described complete reduction of organosolvl ignin to cycloalkanes by using an Al-doped mesoporous silica-supported nickel catalyst under an initial H 2 pressure of 7MPa with heating at 300 8Cf or 8h.Aremarkable8 4% conversion of the lignin into am ixture of branched cycloalkanes waso bserved across ap opulation of carbon fragments from C 8 to > C 20 .…”

Highly Efficient Cleavage of Ether Bonds in Lignin Models by Transfer Hydrogenolysis over Dual‐Functional Ruthenium/Montmorillonite

“…Of the developed strategies (i.e., oxidation, hydrogenolysis, and hydrolysis) to cleave the ether bonds in lignin, hydrogenolysis has attracted significant attention, owing to its high atom economy . The hydrogenolytic cleavage process often involves the use of high‐pressure H 2 , which would result in great potential risk, especially if the reactions were conducted at high temperature. To avoid the use of high‐pressure H 2 , catalytic transfer hydrogenolysis (CTH) by using alcohols as alternative hydrogen resources has been recognized as a highly important lignin‐first biorefinery approach for the reductive catalytic fractionation of lignocellulosic biomass .…”