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Neo acids are highly branched carboxylic acids currently produced from fossil fuels. In this work, we report a strategy to synthesize renewable neo acids with tailored molecular architecture from biomass-derived monomers.

The rising demand for linear alkylbenzene surfactants (LAS) poses an environmental threat as LAS are industrially produced from petroleum using corrosive acid catalysts.

There are few reports of microbial deconstruction or functionalization of the recalcitrant backbone of polyolefins. However, microbes can utilize polyolefin deconstruction products, including n-alkanes. Here, we combined chemical catalysis with bioconversion to valorize polyethylene (PE) deconstruction products. High-density PE (HDPE) was deconstructed via hydrogenolysis over a ruthenium on carbon catalyst. The resultingn-alkane mixture (C4-C35) was utilized as a feedstock for microbial consortia derived from soil from local recycling plants. We found two consortia that utilized the PE-deconstruction product mix as a sole carbon source. We adapted the consortia on a commercially-availablen-alkane mix to reduce the number of species present and enrich for enhanced alkane utilization. Both resulting enriched consortia utilized the PE-deconstruction product mix more effectively than the original (parent) consortia. The predominant metabolite produced by both enriched consortia was a C16-C16wax ester. Wax esters have considerable industrial value, with the longer chain lengths (C32-C36) having the highest value. We identified twoRhodococcus aetherivoransstrains that grow well on C24, indicating this species is important for the functionalization of long-chain alkanes. This work demonstrates that enriched consortia from plastic-enriched environments can be combined with chemical catalysis to valorize polyethylene.SynopsisChemical catalysis can be used to deconstruct polyethylene waste material to produce a mixture of alkanes. Enriched environmental microbial consortia can valorize these polyethylene deconstruction products via functionalization that preserves the alkane chain length thus minimizing CO2production.

Food waste (FW) remains a global challenge due to the increasing demand for food production to support a growing global population and the lack of effective waste management technologies for recycling and upcycling. Unique compounds in FW – such as carbohydrates, proteins, lignin, fats, and extractives – can be repurposed to produce important biobased fuels, bulk chemicals, dietary supplements, adsorbents, and antibacterial products, among many others. We review the thermal and thermocatalytic FW valorization strategies and the fundamental pathways. We discuss the potential integration of various valorization processes, their economic viability, the technical and marketing challenges, and the need for further developments. By overcoming several technical hurdles, repurposing FW into modular plants can create exciting economic and environmental prospects.

Despite progress in the depolymerization of lignin, only a few studies convert the obtained monomers to value-added products. Here we introduce a strategy to synthesize branched benzene lubricant (BBL) and branched cyclic lubricant (BCL) base oils from lignin-derived monomers and aldehyde. We perform carbon–carbon coupling via Bronsted acid-catalyzed hydroxyalkylation/alkylation (HAA) then hydrodeoxygenation (HDO). Optimum HAA reaction conditions achieve up to 90% guaiacol conversion and an HAA product containing 76% BBL and 24% enal condensation product over a P-SiO2 catalyst. Subsequent HDO of HAA products over an Ir-ReOx/SiO2 catalyst produces a lubricant-ranged mixture of BCL (C24) up to yield (82%) and small fractions of dodecyl cyclohexane and C10 and C15 carbons alkanes. The kinematic viscosity, viscosity index, and Noack volatility of these base oils are comparable to commercial petroleum-derived poly α-olefin Group IV and refrigerant base oils. This approach provides a sustainable pathway for replacing petroleum-derived base oils.

The cost of sugar production remains a key challenge in future lignocellulosic biorefineries. We demonstrate that ZnBr2, an inexpensive inorganic salt, provides nearly theoretical yields of glucose and xylose in one-step from poplar wood at 85 °C and short reaction times at molten salt hydrate (MSH) conditions without an acid. Catalytic depolymerization of the isolated MSH lignin, using a CoS2 catalyst, yields 17% phenol-like monomers compared to only 1% produced from the acidified MSH lignin. Reductive catalytic fractionation of MSH lignin over Ru/C resulted in two times higher total monomer yield compared to the AMSH lignin. Both the lignin samples were characterized using 2D HSQC NMR and the thioacidolysis method. Thioacidolysis studies reveal 8.4% and 1.8% of β-O-4 linkages in MSH and acidified MSH lignin, respectively. Thermodynamic modeling and 13C NMR spectroscopy indicate that the effectiveness of this catalyst arises from the strong interaction of the Lewis acidic zinc cation (Zn2+) with the coordinated water molecules resulting in hydrolysis of the metal aquo complex and to the salt-driven increase in the H+ activity coefficient. Techno-economic analysis demonstrates that despite being slower, the ZnBr2 MSH media has cost advantages, compared to conventional hydrolysis and even to the LiBr and ZnBr2 AMSH, due to the higher quality of lignin.

Biorefinery and paper pulping lignins, referred hereto as technical lignins, contain condensed C–C interunit linkages. These robust C–C linkages with higher bond dissociation energies are difficult to disrupt under hydrogenolysis conditions, which are generally used for cleaving C–O bonds of native lignin in biomass or model C–O linked compounds. Thus, selective interunit C–C cleavage to release aromatic monomers for high-value applications is a challenge. We report an effective catalytic system to cleave such C–C bonds selectively under mild conditions. A representative methylene-linked C–C model dimer achieves 88% yield of mainly two aromatic monomers within 1.5 h at a reasonably low temperature (250 °C) using a commercial CoS2 catalyst. Aromatic monomers convert to nonaromatic products upon the reaction for a prolonged time. The interunit C–C bond of the dimer become unreactive to cleavage upon dehydroxylation of aromatic rings, while the methoxyl group has little effect on the cleavage. β-1 and 5-5 C–...

Selective microwave heating can significantly impact the performance of multiphase reactors, such as slurry reactors, where the dispersed (solid particles) and continuum (liquid) phases have different dielectric properties. Lack of tools to measure and predict the temperature difference between the dispersed and continuum phases hinders the understanding and optimization of microwave-heated slurry reactors. We utilize experiments, theory, and multiscale simulations to investigate microwave heating of slurries consisting of microwave absorbing solid particles dispersed in a non-polar liquid. Using controlled experiments and mathematical modeling, we propose an ideal slurry reactor and develop analytical expressions to predict the temperature evolution of the solid and liquid phases during microwave heating. Our experiments show a strong impact of the solid material and concentration on the heating rate of slurries, whereas no difference is observed in conventionally heated slurries. We also perform multiscale simulations of microwave-heated slurries employing a coarse-graining methodology to handle the large separation of length scales in slurries and compare them against experiments.

The manufacture of furfural and 5-hydroxymethylfurfural (HMF), promising renewable platforms for bio-products, with high carbon efficiency is a challenge because of their undesired polymerization to humins. Here, we present an integrated process in inorganic salt solution to overcome this challenge. First, sugar biopolymers yield high monosaccharides (>90%) via efficient saccharification at low temperature. Second, monosaccharides in hydrolysates undergo efficient dehydration in biphasic solvents, assisted by the Bronsted acidity of the salt solution and the added inorganic Lewis acid. The salt solution exhibits high carbon efficiency in furfural and 5-hydroxymethylfurfural (HMF) products (>80 mol%) when compared with the analogous non-salt systems due to the cooperativity of the dual acidity and the higher viscosity of the salt solution than water and the concurrent reactive extraction of products. The process integration makes the separation of the aqueous phase easy, demonstrating nearly comparative activity upon recycling. Intact lignocellulose also achieves high yields of the dehydration products via one-pot depolymerization and saccharification, followed by dehydration. In addition, we elucidate the reasons for the high saccharification efficiency of the salt solution by correlating the effective acidity from the electrode potential and Hammett acidity measurements.

Energy-efficient catalytic conversion of biomass intermediates to functional chemicals can make bio-products viable. Herein, we report an efficient and low temperature aerobic oxidation of xylose to xylaric acid, a promising bio-based chemical for the production of glutaric acid, over commercial catalysts in water. Among several heterogeneous catalysts investigated, Pt/C exhibits the best activity. Systematic variation of reaction parameters in the pH range of 2.5 to 10 suggests that the reaction is fast at higher temperatures but high C-C scission of intermediate C5 -oxidized products to low carbon carboxylic acids undermines xylaric acid selectivity. The C-C cleavage is also high in basic solution. The oxidation at neutral pH and 60 °C achieves the highest xylaric acid yield (64 %). O2 pressure and Pt amount have significant influence on the reactivity. Decarboxylation of short chain carboxylic acids results in formation of CO2 , causing some carbon loss; however, such decarboxylation is slow in the presence of xylose. The catalyst retained comparable activity, in terms of product selectivity, after five cycles with no sign of Pt leaching.

Lignocellulosic material (LCM) is promising alternative resource for sustainable energy production such as ethanol and butanol and biohydrogen. Cellulose is an abundant renewable polymer of LCM found in plant cell walls (30–50%). The high crystallinity of cellulose makes it recalcitrant to hydrolysis into its individual sugar subunits for biofuels production. Moreover, ionic liquids are considered as green solvents and have been used for biomass solubilization. The present work describes three properties: Kamlet–Taft (K–T) parameters, viscosity and surface tension of five imidazolium-based ionic liquids (ILs); namely [C 2 mim][OAc], [C 4 mim][OAc], [C 2 mim][Cl], [C 4 mim][Cl] and [C 4 mims][BF 4 ], and their efficiency in the cellulose structural transformation for improved enzymatic glucose recovery. Crystalline cellulose was treated with ILs at two different temperatures, i.e. 100 and 130 °C for 5 and 2 h, respectively, with 10% solid loading followed by enzymatic saccharification using 10 and 20 FPU/g substrate of commercial cellulases. ILs treatment of crystalline cellulose significantly reduces the crystallinity, which resulted in a very sharp increase of sugar yields after enzymatic saccharification. Cellulose treated for 130 °C/2 h resulted in better glucose yields as compared to 100 °C/5 h. ILs comprising acetate anion resulted in highest glucose yields and chloride based ILs performed moderately, whereas BF 4 − based IL was ineffective in transforming the cellulose structure. In order to decipher the possible reasons of varying efficiency of these ILs, the K–T parameters; hydrogen bond acidity (α), hydrogen bond basicity (β), solvent polarizability (π ∗ ), kinematic viscosity (η) and surface tension (σ) were calculated for 100 and 130 °C. These results show that, among all the properties of ILs, hydrogen bond basicity (β) is relatively more important than kinematic viscosity and surface tension for impacting the structural transformation and subsequent enzymatic hydrolysis. [C 2 mim][OAc] with high β value (1.32) and lower viscosity (4.4 cSt/s) and surface tension (30.3 mN/m) was found to be most efficient in cellulose transformation resulting in higher glucose yields (89.8%) upon saccharification. Effect of size of cation and anion of ILs and properties of regenerated cellulose is also examined by PXRD and FT-IR to further support the findings.

Utilization of renewable carbon source, especially non-food biomass is critical to address the climate change and future energy challenge. Current chemical and enzymatic processes for producing cellulosic sugars are multistep, and energy- and water-intensive. Techno-economic analysis (TEA) suggests that upstream lignocellulose processing is a major hurdle to the economic viability of the cellulosic biorefineries. Process intensification, which integrates processes and uses less water and energy, has the potential to overcome the aforementioned challenges. Here, we demonstrate a one-pot depolymerization and saccharification process of woody biomass, energy crops, and agricultural residues to produce soluble sugars with high yields. Lignin is separated as a solid for selective upgrading. Further integration of our upstream process with a reactive extraction step makes energy-efficient separation of sugars in the form of furans. TEA reveals that the process efficiency and integration enable, for the first time, economic production of feed streams that could profoundly improve process economics for downstream cellulosic bioproducts.

The fate of levoglucosan after it forms during cellulose pyrolysis was investigated experimentally using time-resolved thermogravimetric analysis/differential scanning calorimetric combined with mass spectrometry measurements followed by high performance liquid chromatography and gel filtration chromatography of the pyrolysis residue. This study indicates that levoglucosan formed during cellulose pyrolysis is initially a liquid that undergoes two simultaneous, competing processes of evaporation and polymerization. Levoglucosan that evaporates escapes the high temperature pyrolysis zone while levoglucosan that polymerizes is trapped in the pyrolysis zone and dehydrates to low molecular weight volatile products and char. The oligosaccharides that form during polymerization are subject to two simultaneous reaction pathways: direct decomposition to low molecular weight products such as water, carbon dioxide, 5-hydroxymethylfurfural, furfural, furan and acetic acid, and formation of polysaccharides that eventually dehydrate to char and low molecular weight volatiles. Based on the experimental observations and quantitative measurements, a modified cellulose pyrolysis pathway involving levoglucosan as the major intermediate is proposed.