Solvent-based recycling of plastic waste is a promising approach for cleaning polymer chains without breaking them. However, the time required to actually dissolve the polymer in a lab environment can take hours. Different factors play a role in polymer dissolution, including temperature, turbulence, and solvent properties.
View Article and Find Full Text PDFA biomass-derived difuran compound, denoted as HAH (HMF-Acetone-HMF), synthesized by aldol-condensation of 5-hydroxyfurfural (HMF) and acetone, can be partially hydrogenated to provide an electron-rich difuran compound (PHAH) for Diels-Alder reactions with maleimide derivatives. The nitrogen (N) site in the maleimide can be substituted by imidation with amine-containing compounds to control the hydrophobicity of the maleimide moiety in adducts of furans and maleimide by Diels-Alder reaction, denoted as norcantharimides (Diels-Alder adducts). The structural effects on the toxicity of various biomass-derived small molecules synthesized in this manner to regulate biological processes, defined as low molecular weight (≤ 1000 g/mol) organic compounds, were investigated against diverse microbial and mammalian cell types.
View Article and Find Full Text PDFThe engineered structures and active sites of enzyme catalysts give rise to high catalytic activity and selectivity toward desired reactions. We have employed a biomass-derived difuran compound to append N-substituted maleimides with amino acid (glutamic acid) substitution by Diels-Alder reaction to mimic the chemical functional groups that comprise the active site channels in enzyme catalysts. The difunctionality of the biomass-derived difuran allows production of Diels-Alder adducts by appending two amino acid moieties to form a difunctional organocatalyst.
View Article and Find Full Text PDFWaste plastics are an abundant feedstock for the production of renewable chemicals. Pyrolysis of waste plastics produces pyrolysis oils with high concentrations of olefins (>50 weight %). The traditional petrochemical industry uses several energy-intensive steps to produce olefins from fossil feedstocks such as naphtha, natural gas, and crude oil.
View Article and Find Full Text PDFEnvironmental concerns over waste plastics' effect on the environment are leading to the creation of biodegradable plastics. Biodegradable plastics may serve as a promising approach to manage the issue of environmental accumulation of plastic waste in the ocean and soil. Biodegradable plastics are the type of polymers that can be degraded by microorganisms into small molecules (e.
View Article and Find Full Text PDFMaterial Recovery Facilities (MRFs) are crucial players in achieving a circular economy. MRFs receive complex waste streams and separate valuable recyclables from these mixtures. This study conducts techno-economic analysis (TEA) to estimate the net present value (NPV) and life cycle assessment (LCA) to estimate different environmental impacts of a commercial scale standalone, single-stream MRF to assess the economic feasibility and environmental impacts of recovering valuable recyclables from an MRF processing 120,000 tonnes per year (t/y).
View Article and Find Full Text PDFWe studied the hydrogenation at temperatures from 313 - 393 K of a biomass-derived platform molecule, 5-hydroxymethyl furfural (HMF)-Acetone-HMF (HAH) over Pd, Ru, and Cu based catalysts. HAH was selectively hydrogenated to produce partially-hydrogenated monomers (PHAH) over Cu and Ru catalysts and to fully-hydrogenated HAH monomers (FHAH) over the Ru catalyst. Pd based catalysts yielded a mixture of partially and fully hydrogenated monomers.
View Article and Find Full Text PDFAcetalization of biomass-derived 5-hydroxymethyl furfural (HMF) with pentaerythritol produced a difuran (HPH) monomer in the presence of an acid catalyst. A recyclable polymer was then synthesized by Diels-Alder reaction of bismaleimide and the HMF-derived difuran (HPH). A polyurethane, produced from the Diels-Alder polymer has a higher glass transition temperature than a polyurethane, produced from ethylene glycol.
View Article and Find Full Text PDFIn their Editorial to the Special Issue on The Chemistry of Waste Plastics Upcycling, the Guest Editors Adam Guss, George Huber, Carol Lin, Xianzhi Meng, Hugh O'Neill, Arthur Ragauskas, Jia Wang, Yanqin Wang, and Frederik Wurm highlight some of the increasingly urgent efforts being made by chemists to address challenges related to the fate of plastics at the end of, their useful lives and the valorization of plastic waste.
View Article and Find Full Text PDFOne promising approach to recycle multicomponent plastic waste (e. g., multilayer plastic films) is selective dissolution.
View Article and Find Full Text PDFFunctional polyurethanes and polyesters with tunable properties were synthesized from biomass-derived 5-hydroxymethyl furfural (HMF)-Acetone-HMF (HAH) monomers. HAH can be selectively hydrogenated over Cu and Ru catalysts to produce partially-hydrogenated (PHAH) and fully-hydrogenated (FHAH). The HAH units in these polymers improve the thermal stability and stiffness of the polymers compared to polyurethanes produced with ethylene glycol.
View Article and Find Full Text PDFMany plastic packaging materials manufactured today are composites made of distinct polymer layers (i.e., multilayer films).
View Article and Find Full Text PDFCatalytic strategies were developed to synthesize and release chemicals for applications in fine chemicals, such as drugs and polymers, from a biomass-derived chemical, 5-hydroxymethyl furfural (HMF). The combination of the diene and aldehyde functionalities in HMF enabled catalytic production of acetalized HMF derivatives with diol or epoxy reactants to allow reversible synthesis of norcantharimide derivatives upon Diels-Alder reaction with maleimides. Reverse-conversion of the acetal group to an aldehyde yielded mismatches of the molecular orbitals in norcantharimides to trigger retro Diels-Alder reaction at ambient temperatures and released reactants from the coupled molecules under acidic conditions.
View Article and Find Full Text PDFWe report on the synthesis and characterization of novel mesoporous chiral polyboronates obtained by condensation of (,)/(,)-hexane-1,2,5,6-tetrol (HT) with simple aromatic diboronic acids (e.g., 1,3-benzenediboronic acid) (BDB).
View Article and Find Full Text PDFWe report a process to produce a versatile platform chemical from biomass-derived fructose for organic dye, polymer, and liquid fuel industries. An aldol-condensed chemical (HAH) is synthesized as a platform chemical from fructose by catalytic reactions in acetone/water solvent with non-noble metal catalysts (e.g.
View Article and Find Full Text PDFThis study reports on a comparative study of acid hydrotropic fractionation (AHF) of birch wood using maleic acid (MA) and p-toluenesulfonic acid (p-TsOH). Under the same level of delignification, lignin dissolved by MA is much less condensed with a higher content of ether aryl β-O-4 linkages. Lignin depolymerization dominated in MA hydrotropic fractionation (MAHF) and resulted in a single lower molecular weight peak, in contrast to the competitive depolymerization and repolymerization in p-TsOH AHF with a bimodal distribution.
View Article and Find Full Text PDFEnzymes selectively hydrolyze the carbohydrate fractions of lignocellulosic biomass into corresponding sugars, but these processes are limited by low yields and slow catalytic turnovers. Under certain conditions, the rates and yields of enzymatic sugar production can be increased by pretreating biomass using solvents, heat and dilute acid catalysts. However, the mechanistic details underlying this behavior are not fully elucidated, and designing effective pretreatment strategies remains an empirical challenge.
View Article and Find Full Text PDFWe show that platinum displays a self-adjusting surface that is active for the hydrogenation of acetone over a wide range of reaction conditions. Reaction kinetics measurements under steady-state and transient conditions at temperatures near 350 K, electronic structure calculations employing density-functional theory, and microkinetic modeling were employed to study this behavior over supported platinum catalysts. The importance of surface coverage effects was highlighted by evaluating the transient response of isopropanol formation following either removal of the reactant ketone from the feed, or its substitution with a similarly structured species.
View Article and Find Full Text PDFGlucose electrolysis offers a prospect of value-added glucaric acid synthesis and energy-saving hydrogen production from the biomass-based platform molecules. Here we report that nanostructured NiFe oxide (NiFeO) and nitride (NiFeN) catalysts, synthesized from NiFe layered double hydroxide nanosheet arrays on three-dimensional Ni foams, demonstrate a high activity and selectivity towards anodic glucose oxidation. The electrolytic cell assembled with these two catalysts can deliver 100 mA cm at 1.
View Article and Find Full Text PDFThe annual global production of plastics reached 335 million metric tons in 2016. Most waste plastics are landfilled or enter the natural environment in an uncontrolled manner. Pyrolysis can convert waste plastics, such as polyethylene (PE), to smaller hydrocarbons that can be used as fuels or chemicals.
View Article and Find Full Text PDFThe hydrolysis of lactose in aqueous solutions and dairy waste streams was studied using Amberlyst 70 as a heterogeneous acid catalyst in a continuous-flow packed-bed reactor. The catalyst was stable during hydrolysis of an aqueous lactose feed but deactivated owing to mineral poisoning when the dairy waste Greek yogurt acid whey (GAW) was used as the feedstock. A catalyst deactivation model was developed and showed that the deactivation of the Amberlyst 70 catalyst was proportional to the amounts of cations, urea and amino acids flowing through the catalyst bed.
View Article and Find Full Text PDFEthanol is an important bulk chemical with diverse applications. Biomass-derived ethanol is traditionally produced by fermentation. Direct cellulose conversion to ethanol by chemocatalysis is particularly promising but remains a great challenge.
View Article and Find Full Text PDFReaction pathways for the conversion of cellulose into C -C monoalcohols by supercritical methanol depolymerization and hydrodeoxygenation (SCM-DHDO) over a CuMgAl oxide catalyst have been elucidated using a range of model compounds. SCM-DHDO of intermediate oxygenates including glycerol, methyl lactate, and 1,2-ethanediol produces similar products as those produced from the SCM-DHDO of cellulose. The pathway to C -C monoalcohols occurs through rapid C-C coupling reactions between methanol and diols followed by C-C scission between vicinal alcohol groups to produce two monoalcohols.
View Article and Find Full Text PDFA methodology for the synthesis of gasoline-range fuels from carbon neutral resources is introduced. Sorbitol, a sugar-based compound, was employed as a raw material because the compound is readily obtained from cellulose. Gasoline-range hydrocarbons were produced via hydrodeoxygenation (HDO) on zirconium phosphate-supported Pd-bimetallic (Pt-Pd, Ru-Pd, Ni-Pd, Fe-Pd, Co-Pd, W-Pd) catalysts.
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