Abstract:Lignin is one of the most promising sources of renewable aromatic hydrocarbons. Current methods for its extraction from lignocellulosic biomass-which include the kraft, sulfite, and organosolv processes-result in the rapid formation of carbon-carbon bonds, leading to a condensed lignin that cannot be effectively depolymerized into its constituent monomers. Treatment of lignocellulosic biomass with aldehydes during lignin extraction generates an aldehyde-stabilized lignin that is uncondensed and can be converte… Show more
“…Afterwards, they compared different protecting reagents (aldehydes, ketones, dimethyl carbonate, phenylboronic acid), with formaldehyde giving the highest yield (46 wt %) of phenolic monomers, followed by propionaldehyde (42 wt %) and acetaldehyde (37 wt %) . The aldehyde‐stabilized lignin could be readily selectively dissolved in an organic solvent and catalytically depolymerized to a near‐theoretical yield of phenolic monomers (40–50 wt % for a typical hardwood) …”
Section: Other Strategies For Improving the Monomer Yields And Potentmentioning
The efficient valorization of lignin could dictate the success of the 2nd generation biorefinery. Lignin, accounting for on average a third of the lignocellulosic biomass, is the most promising candidate for sustainable production of value‐added phenolics. However, the structural alteration induced during lignin isolation is often depleting its potential for value‐added chemicals. Recently, catalytic reductive depolymerization of lignin has appeared to be a promising and effective method for its valorization to obtain phenolic monomers. The present study systematically summarizes the far‐reaching and state‐of‐the‐art lignin valorization strategies during different stages, including conventional catalytic depolymerization of technical lignin, emerging reductive catalytic fractionation of protolignin, stabilization strategies to inhibit the undesired condensation reactions, and further catalytic upgrading of lignin‐derived monomers. Finally, the potential challenges for the future researches on the efficient valorization of lignin and possible solutions are proposed.
“…Afterwards, they compared different protecting reagents (aldehydes, ketones, dimethyl carbonate, phenylboronic acid), with formaldehyde giving the highest yield (46 wt %) of phenolic monomers, followed by propionaldehyde (42 wt %) and acetaldehyde (37 wt %) . The aldehyde‐stabilized lignin could be readily selectively dissolved in an organic solvent and catalytically depolymerized to a near‐theoretical yield of phenolic monomers (40–50 wt % for a typical hardwood) …”
Section: Other Strategies For Improving the Monomer Yields And Potentmentioning
The efficient valorization of lignin could dictate the success of the 2nd generation biorefinery. Lignin, accounting for on average a third of the lignocellulosic biomass, is the most promising candidate for sustainable production of value‐added phenolics. However, the structural alteration induced during lignin isolation is often depleting its potential for value‐added chemicals. Recently, catalytic reductive depolymerization of lignin has appeared to be a promising and effective method for its valorization to obtain phenolic monomers. The present study systematically summarizes the far‐reaching and state‐of‐the‐art lignin valorization strategies during different stages, including conventional catalytic depolymerization of technical lignin, emerging reductive catalytic fractionation of protolignin, stabilization strategies to inhibit the undesired condensation reactions, and further catalytic upgrading of lignin‐derived monomers. Finally, the potential challenges for the future researches on the efficient valorization of lignin and possible solutions are proposed.
“…6c and Fig. S29) 28 . This lignin-derived oil was then selectively hydrogenated to the oxygenated 2-methoxy-4propylcyclohexanol (1, having -OH and -OCH 3 retained) with suppressed deoxygenation using PtRhAu catalyst.…”
Section: Resultsmentioning
confidence: 96%
“…We further demonstrate the versatility of PtRhAu catalysts in an integrated lignin biore nery to obtain oxygenated chemicals directly from lignocellulosic biomass. We rst converted birch wood to ligninderived oils containing 4-propylsyringol (4PS) and/or 4-propylguaiacol (4PG) using aldehyde-assisted fractionation (AAF) followed by hydrogenolysis 5,28 . These lignin-derived oils were then selectively hydrogenated and funneled to a single OFG-rich chemical 2-methoxy-4-propylcyclohexanol for synthetic perfumes using our novel electrocatalysts under ambient conditions.…”
Catalytic hydrogenation of bio-oil provides an avenue to produce renewable chemicals. To this end, electrocatalytic hydrogenation is especially interesting when powered using low-carbon electricity; however, it has to date lacked the needed selectivity: when hydrogenating bio-oil to oxygenated hydrocarbons, for example, it reduces the desired oxygenated groups (-OH and -OCH3). Here we report that Rh and Au modulate electronic structure of Pt and steer intermediate energetics to favor the hydrogenation while suppressing deoxygenation using computational studies and in-situ spectroscopies. PtRhAu catalysts achieve a record 47% faradaic efficiency (FE) and a partial current density (Jp) of 28 mA·cm-2 toward oxygenated 2-methoxycyclohexanol from lignin-derived guaiacol under room temperature and ambient pressure, representing 1.5x FE and 3.5x Jp increases compared to the best prior reports. We further demonstrate an integrated lignin biorefinery where wood-derived lignin oils are selectively hydrogenated and funneled to the oxygenated 2-methoxy-4-propylcyclohexanol using PtRhAu catalysts.
“…Although this functionalization was first reported with formaldehyde, it has since been shown that this reaction works efficiently with a large array of aldehydes. It was also notably shown that, by using a variety of multiple aldehydes, the solubility of the resulting lignins could be tuned, making them soluble in vastly different solvents from water to toluene [97][98][99]. This range of solubility could be further used to tailor lignin incorporation into several polymers.…”
Section: Reaction Of Aliphatic Hydroxyl Groupsmentioning
Trends in Chemistry opportunities for the production of controlled lignin structures and the incorporation of these structures into materials, which we describe later.
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