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Concerns over the sustainability and end‐of‐life properties of fossil‐derived surfactants have driven interest in bio‐based alternatives. Lignocellulosic biomass with its polar functional groups is an obvious feedstock for surfactant production but its use is limited by process complexity and low yield. Here, we present a simple two‐step approach to prepare bio‐based amphiphiles directly from hemicellulose and lignin at high yields (29 % w/w based on the total raw biomass and >80 % w/w of these two fractions). Acetal functionalization of xylan and lignin with fatty aldehydes during fractionation introduced hydrophobic segments and subsequent defunctionalization by hydrogenolysis of the xylose derivatives or acidic hydrolysis of the lignin derivatives produced amphiphiles. The resulting biodegradable xylose acetals and/or ethers, and lignin‐based amphiphilic polymers both largely retained their original natural structures, but exhibited competitive or superior surface activity in water/oil systems compared to common bio‐based surfactants. [ABSTRACT FROM AUTHOR]

Lignin oxidation offers a potential sustainable pathway to oxygenated aromatic molecules. However, current methods that use real lignin tend to have low selectivity and a yield that is limited by lignin degradation during its extraction. We developed stoichiometric and catalytic oxidation methods using 2,3‐dichloro‐5,6‐dicyano‐1,4‐benzoquinone (DDQ) as oxidant/catalyst to selectively deprotect the acetal and oxidize the α‐OH into a ketone. The oxidized lignin was then depolymerized using a formic acid/sodium formate system to produce aromatic monomers with a 36 mol % (in the case of stoichiometric oxidation) and 31 mol % (in the case of catalytic oxidation) yield (based on the original Klason lignin). The selectivity to a single product reached 80 % (syringyl propane dione, and 10–13 % to guaiacyl propane dione). These high yields of monomers and unprecedented selectivity are attributed to the preservation of the lignin structure by the acetal. Knock on wood: 2,3‐Dichloro‐5,6‐dicyano‐1,4‐benzoquinone is able to selectively remove the acetal and oxidize the α‐OH of acetal‐protected lignin. The resultant oxidized lignin generated syringyl and guaiacyl propane diketons in high monomer yield (31–36 % on the base of original Klason lignin) and with high selectivity (90 %) in formic acid/sodium formate, thanks to nearly complete extraction of lignin and preservation of the β‐O‐4 linkages. [ABSTRACT FROM AUTHOR]

Reaction kinetics were studied to quantify the effects of polar aprotic organic solvents on the acid-catalyzed conversion of xylose into furfural. A solvent of particular importance is γ-valerolactone (GVL), which leads to significant increases in reaction rates compared to water in addition to increased product selectivity. GVL has similar effects on the kinetics for the dehydration of 1,2-propanediol to propanal and for the hydrolysis of cellobiose to glucose. Based on results obtained for homogeneous Brønsted acid catalysts that span a range of p Ka values, we suggest that an aprotic organic solvent affects the reaction kinetics by changing the stabilization of the acidic proton relative to the protonated transition state. This same behavior is displayed by strong solid Brønsted acid catalysts, such as H-mordenite and H-beta. [ABSTRACT FROM AUTHOR]

The use of metal oxide overcoats over supported nanoparticle catalysts has recently led to impressive improvements in catalyst stability and selectivity. The deposition of alumina is especially important for renewable catalysis due to its robustness in liquid-phase conditions. However, there are limited reports of work on alumina deposition and stabilization that goes beyond atomic layer deposition (ALD). Here, we present a layer-by-layer deposition technique for the controlled formation of conformal alumina overcoats in the liquid phase. This technique is easy to perform in common wet chemistry conditions. Alternated exposure of the substrate to stoichiometric amounts of aluminum alkoxide and water in liquid-phase conditions leads to the formation of a porous overcoat that was easily tunable by varying synthesis parameters. The deposition of 60 Al 2 O 3 layers onto Al 2 O 3 -supported copper nanoparticles suppressed irreversible deactivation during the liquid-phase hydrogenation of furfural – a key biomass-derived platform molecule. The porous overcoat leads to highly accessible metal sites, which significantly reduces the partial site blocking observed in equivalent overcoats formed by ALD. We suggest that the ease of scalability and the high degree of control over the overcoat’s properties during liquid-phase synthesis could facilitate the development of new catalyst overcoating applications. [ABSTRACT FROM AUTHOR]