The generation of primary aerosols from biomass hinders the production of biofuels by pyrolysis, intensifies the environmental impact of forest fires, and exacerbates the health implications associated with cigarette smoking. High speed photography is utilized to elucidate the ejection mechanism of aerosol particles from thermally decomposing cellulose at the timescale of milliseconds. Fluid modeling, based on first principles, and experimental measurement of the ejection phenomenon supports the proposed mechanism of interfacial gas bubble collapse forming a liquid jet which subsequently fragments to form ejected aerosol particles capable of transporting nonvolatile chemicals. Identification of the bubble-collapse/ejection mechanism of intermediate cellulose confirms the transportation of nonvolatile material to the gas phase and provides fundamental understanding for predicting the rate of aerosol generation.

Reductive catalytic fractionation (RCF) is a promising approach to fractionate lignocellulose and convert lignin to a narrow product slate. To guide research towards commercialization, cost and sustainability must be considered....

Alkaline aerobic oxidation is an effective way to produce valuable aromatic chemicals from lignin.

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We conduct a combined experimental and computational study to reveal the kinetics of tandem glucose isomerization and fructose dehydration to 5-hydroxymethylfurfural (HMF) over a

Glycerol, a commodity by-product of the biodiesel industry, has value as a fuel feedstock and chemical intermediate. It is also a simple prototype of sugars and carbohydrates. Through catalytic partial oxidation (CPOx), glycerol can be converted into syngas without the addition of process heat. We explored the CPOx of glycerol using a nebulizer to mix droplets with air at room temperature for reactive flash volatilization. Introducing this mixture over a noble-metal catalyst oxidizes the glycerol at temperatures over 600 degrees C in 30-90 ms. Rhodium catalysts produce equilibrium selectivity to syngas, while platinum catalysts produce mainly autothermal non-equilibrium products. The addition of water to the glycerol increases the selectivity to H(2) by the water gas shift reaction and reduces non-equilibrium products. However, water also quenches the reaction, resulting in a maximum in H(2) production at a steam/carbon ratio of 2:3 over a Rh-Ce catalyst. Glycerol without water produces a variety of chemicals over Pt, including methylglyoxal, hydroxyacetone, acetone, acrolein, acetaldehyde, and olefins.

The main paths by which zeolites carry out the dehydration of fructose to HMF and the rehydration of HMF to levulinic acid in aqueous solutions are elucidated using an H-BEA zeolite with SiO2/Al2O3 = 18 (H-BEA-18) as a representative solid acid catalyst. Specifically, the relative role of homogeneous chemistry (both solvent- and zeolite-induced), the effect of external surface acid sites, and the effect of adsorption of products and reactants on the catalyst for these reactions is delineated. We found that H-BEA-18 increases the conversion of fructose and HMF in part by catalyzing fructose isomerization to glucose and HMF rehydration to formic and levulinic acids, respectively. The glucose-to-fructose isomerization is caused by octahedral aluminum atoms that act as Lewis acid sites as shown by 1H and 13C NMR. These Lewis sites are formed during calcination and are stable under reaction conditions. They also catalyze reactions to unknown products from both fructose and HMF. The acids produced from HMF rehydration dissolve aluminosilicate species from the zeolite, which also catalyze some of the undesired side reactions. We show that the decrease of the initial pH due to the addition of the zeolite and the catalysis by sites on the external surface of the zeolite have a negligible contribution to the chemistry under most conditions investigated. H-BEA-18 more readily converts HMF than fructose, due to strong preferential adsorption of HMF, furfural, and levulinic acid compared to sugars. Under mildly acidic conditions (without the addition of inorganic acids) that are environmentally preferred, zeolites can increase the conversion of HMF and the selectivity to levulinic acid many-fold. This provides an indication that heterogeneous materials may be superior in the production of levulinic acid from HMF.

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