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At least 91 records · Page 5

p -Coumaroylated Lignins Are Natively Produced in Three Rosales Families

Carbon-rich plant cell walls contain biopolymers that, with some processing, could replace fossil fuels as a major component of the current petrochemical production. To realize this, biorefineries need to be paired with biomass that during the deconstruction and fractionation processes transforms into the desired products. One component of interest is p-coumarate that, in some species, can account for up to 1% of the biomass’ dry weight. When p-coumarate is present in eudicot cell walls, it is mostly part of the suberin (bark and root), acylates the γ-hydroxy group of the lignin, in part of the tannins, or is a metabolite. The current understanding of eudicot plant cell wall composition is that the lignin is sometimes acylated with acetate and rarely with hydroxycinnamates (p-coumarate or ferulate). This study identified a clear division in the Rosales in which three families produce p-coumaroylated lignins whereas the other six families showed no evidence of the trait.

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Technoeconomic Analysis of a Novel Microwave Process to Produce Ethylene from Methane

Ethylene is a critical feedstock in industrial processes, serving as a raw material in the petrochemical industry to produce plastics and commodity chemicals. Conventional ethylene production routes are energy-intensive and contribute substantially to the carbon footprint of chemical manufacturing. In this study, an industrial-scale novel microwave process was simulated using ASPEN Plus to assess its economic viability. Technoeconomic analysis confirmed the economic competitiveness of the novel microwave process, with a levelized cost of ethylene of USD 0.51/kg compared to USD 0.56/kg for the conventional base case. Key economic drivers of the process were identified, and sensitivity analyses were conducted to evaluate their impact on project economics. Furthermore, 87.7% of the total utility consumption in the novel microwave process is electricity, highlighting its potential to contribute to the electrification of the chemical industry. The findings of this study confirm the economic feasibility of both industrial-scale microwave reactors and modular plant configurations for the production of ethylene from methane, offering a promising alternative to conventional processes.

electromagnetic radiation↗

Ionic-liquid-Assisted Fabrication of Lignocellulosic Thin Films with Tunable Hydrophobicity

Thin films with enhanced water repellency and mechanical strength can be fabricated from renewable lignocellulosic feedstock as a replacement for petrochemical-derived synthetic polymers, such that it minimizes life cycle impact on the environment and human health. In this work, hybrid poplar wood, either untreated (control) or pretreated with hot water at 160 °C for 20 min (HWE-20), 60 min (HWE-60), and 90 min (HWE-90), was dissolved in 1-ethyl-3-methylimidazolium acetate and regenerated to fabricate thin films. The HWE-90 films were enriched in lignin by 74%, specifically on the surface, which along with hemicellulose depletion imparted hydrophobicity (108° water contact angle) when compared to the control (56°), HWE-20 (77°), and HWE-60 (84°) films. They also exhibited 86% reduced water vapor sorption hysteresis and 75% improved storage modulus compared to the control. Thus, we demonstrate how to tune the lignocellulosic film properties via a combination of hot water pretreatment and ionic liquid dissolution.

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Identifying Green Solvent Mixtures for Bioproduct Separation Using Bayesian Experimental Design

Liquid–liquid extraction (LLE) is a widely used technique for the separation and purification of liquid-phase products with applications in various industries, including pharmaceuticals, petrochemicals, and renewable chemistry. A critical step in the design of an LLE process is the selection of appropriate solvents. This study presents a new methodology for identifying solvent mixtures for bioproduct separation using Bayesian experimental design (BED). Motivated by the need for environmentally friendly and effective separation methods, we address the challenge of selecting solvent systems that balance separation efficiency, selectivity, and environmental impact while also tackling the difficulty of separating multiple bioproducts using complex solvent systems. Our approach specifically seeks to predict product partition coefficients (log10 Kp values) as thermodynamic parameters underlying solvent selection. The iterative approach integrates Bayesian optimization with experimental measurements to guide solvent selection and leverages COSMO-RS simulations to enhance high-throughput experimentation. Using the design of solvent systems for the separation of lignin-derived aromatic products via centrifugal partition chromatography (CPC) as a case study, we show that within seven iterations/cycles of the methodology, we can identify new mixtures of green solvents that align with CPC design principles. Furthermore, these results demonstrate the efficacy of the BED framework in optimizing green solvent systems for complex separations, highlighting the potential of this method to advance the field of green chemistry and contribute to the development of sustainable industrial processes.

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Lignin-Derived Methoxyterephthalates for Performance-Advantaged Polymers and Plasticizers

Lignin-derived aromatic carboxylic acids can be produced from oxidative catalytic processes and are promising building blocks for performance-advantaged bioproducts that leverage their inherent heteroatom functionalities. Here, we synthesize 2-methoxyterephthalate and 2,6-dimethoxyterephthalate derivatives by electrochemical carboxylation of guaiacyl- and syringyl-derived lignin monomers obtained from the oxidative deconstruction of lignin. These methoxylated terephthalates are evaluated as comonomers in poly(ethylene terephthalate) (PET) and as plasticizers that could replace petrochemically-derived isophthalate and phthalate, respectively. Specifically, we copolymerize 2-methoxy- and 2,6-dimethoxyterephthalate with dimethyl terephthalate to form several PET copolymers, both of which enable the properties of PET to be tuned, with an incorporation beyond 25% producing amorphous polyesters. At 10 mol % loading in the copolymers, we demonstrate that the bioderived comonomers exhibit comparable behavior to isophthalic acid, a commonly used comonomer in PET, by lowering the crystallinity and melting temperature. Moreover, methoxyterephthalate esters (2-ethylhexyl and butyl) are compared to phthalate and terephthalate ester counterparts used as poly(vinyl chloride) (PVC) plasticizers. The bioderived plasticizers are comparable to the petroleum-derived incumbents in reducing the glass transition temperature and increasing the thermal stability of PVC. Furthermore, the dimethoxyterephthalic esters are expected to have an extended lifetime in the polymer matrix due to their lower volatility and lower diffusion coefficients calculated by molecular dynamic simulations. These results demonstrate that the isophthalate and phthalate components in polyesters and plasticizers, respectively, could be substituted with biobased methoxyterephthalate derivatives.

09 BIOMASS FUELS↗

A Microporous Metal–Organic Framework Incorporating Both Primary and Secondary Building Units for Splitting Alkane Isomers

We demonstrate the assembly of a mononuclear metal center, a hexanuclear cluster, and a V-shaped, trapezoidal tetracarboxylate linker into a microporous MOF featuring an unprecedented 3-nodal (4,4,8)-c lyu topology. Here, the compound, HIAM-302, represents the first example that incorporates both primary building unit (PBU) and hexanuclear secondary building unit (SBU) in one structure, which should be attributed to the desymmetrized geometry of the organic linker. HIAM-302 possesses optimal pore dimensions and can separate mono-branched and di-branched alkanes through selective molecular sieving, which is of significant value in petrochemical industry.

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Muconic acid production from glucose and xylose in Pseudomonas putida via evolution and metabolic engineering

Muconic acid is a bioprivileged molecule that can be converted into direct replacement chemicals for incumbent petrochemicals and performance-advantaged bioproducts. In this study, Pseudomonas putida KT2440 is engineered to convert glucose and xylose, the primary carbohydrates in lignocellulosic hydrolysates, to muconic acid using a model-guided strategy to maximize the theoretical yield. Using adaptive laboratory evolution (ALE) and metabolic engineering in a strain engineered to express the D-xylose isomerase pathway, we demonstrate that mutations in the heterologous D-xylose:H + symporter (XylE), increased expression of a major facilitator superfamily transporter (PP_2569), and overexpression of aroB encoding the native 3-dehydroquinate synthase, enable efficient muconic acid production from glucose and xylose simultaneously. Using the rationally engineered strain, we produce 33.7 g L -1 muconate at 0.18 g L -1 h -1 and a 46% molar yield (92% of the maximum theoretical yield). This engineering strategy is promising for the production of other shikimate pathway-derived compounds from lignocellulosic sugars.

09 BIOMASS FUELS↗

Probing sub-5 Ångstrom micropores in carbon for precise light olefin/paraffin separation

Olefin/paraffin separation is an important but challenging and energy-intensive process in petrochemical industry. The realization of carbons with size-exclusion capability is highly desirable but rarely reported. Herein, we report polydopamine-derived carbons (PDA-Cx, where x refers to the pyrolysis temperature) with tailorable sub-5 Å micropore orifices together with larger microvoids by one-step pyrolysis. The sub-5 Å micropore orifices centered at 4.1–4.3 Å in PDA-C800 and 3.7–4.0 Å in PDA-C900 allow the entry of olefins while entirely excluding their paraffin counterparts, performing a precise cut-off to discriminate olefin/paraffin with sub-angstrom discrepancy. The larger voids enable high C 2 H 4 and C 3 H 6 capacities of 2.25 and 1.98 mmol g –1 under ambient conditions, respectively. Breakthrough experiments confirm that a one-step adsorption-desorption process can obtain high-purity olefins. Inelastic neutron scattering further reveals the host–guest interaction of adsorbed C 2 H 4 and C 3 H 6 molecules in PDA-Cx. This study opens an avenue to exploit the sub-5 Å micropores in carbon and their desirable size-exclusion effect.

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Lignin to adipic acid in a high-yield chemical and biological redox process

Viable manufacturing pathways to produce bio-based chemicals from renewable feedstocks, such as lignin derived from plant biomass, are needed to decarbonize the chemicals manufacturing sector. Converting the recalcitrant lignin polymer to valuable bioproducts remains a longstanding challenge in biorefining, with the highest reported single-product yield from lignin currently around 20 wt%. Most existing lignin depolymerization strategies target aryl–ether bond cleavage, which can produce aromatic monomers in yields of only about 30 wt%, and still as complex mixtures with C–C-linked dimers and oligomers. The recalcitrance of these C–C linkages between aromatic moieties fundamentally limits single-product yields from lignin, prompting the development of strategies to efficiently cleave these C–C bonds. Here, in this study, we show how reductive processing of lignin from poplar accesses a hydrocarbon mixture of alkyl-aromatic monomers and oligomers that is privileged for oxidative conversion to monomeric aromatic carboxylic acids, comprising mostly benzoic acid and phthalic acid isomers in up to 73 wt% monomer yields, using a Co/Mn/Br catalyst. The soil bacterium Pseudomonas putida KT2440 was engineered to convert this mixture of aromatic carboxylic acids to muconolactone, a precursor to bio-based nylons, enabling final adipic acid yields up to 26 wt% (gram adipic acid per gram lignin) with a maximum theoretical yield of 57 wt%. This pairing of reductive and oxidative steps with lignin resembles processes in petrochemical refining and shows how lignin may be converted into a single, valuable bioproduct in high yields.

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Biorenewable and circular polydiketoenamine plastics

Amid growing concerns over the human health and environmental impacts of plastic waste, the most promising solution would be to build a circular plastics economy where sustainability considerations dictate the full life cycle of plastics use including replacing petrochemicals with biorenewables. Here we show that by incorporating the polyketide triacetic acid lactone (TAL) in polydiketoenamines (PDK) we increase the working temperature of these circular plastics, opening the door wider to applications where circularity is urgently needed. By varying the number of carbons of TAL-derived monomers, both polymer properties and recycling efciency are afected. Simply using glucose as the main carbon source, we engineered a process for producing bioTAL under fed-batch fermentation. Furthermore, a systems analysis of this bioprocess under diferent scenarios quantifes the environmental and economic benefts of PDK plastics and the risks when implemented at an industrial scale, providing opportunities in biorenewable circularity.

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Strong and recyclable bio-derived poly(ester amide) hot-melt adhesive

Bio-based adhesives offer inherent advantages over conventional petrochemical-derived systems, including renewable sourcing, reduced environmental impact and potential degradability. However, most bio-based adhesives suffer from poor adhesion strength, limited substrate compatibility and a lack of chemical recyclability. Here, in this work, we present a bio-derived multiblock poly(ester amide) adhesive that leverages microphase segregation between different segments to reconcile mechanical robustness with strong interfacial bonding. Notably, this multiblock architecture is accessed through a one-pot, selective acceptorless dehydrogenative polymerization, obviating the need for multistep synthesis. The materials exhibit excellent adhesion across a range of substrates including metals, glass and wet wood surpassing commercial benchmarks, while also demonstrating thermal stability, tunable mechanical properties and closed-loop chemical recyclability even in the presence of other commodity plastics. Furthermore, the adhesive strength of these materials could be tuned for various potential applications through control over the chemical composition of the polymer. By integrating renewable feedstocks, high-performance functionality and efficient chemical circularity within a single platform, this work provides a viable pathway toward more sustainable adhesive technologies and contributes to advancing circular materials manufacturing.

09 BIOMASS FUELS↗

Flexible polyurethanes, renewable fuels, and flavorings from a microalgae oil waste stream

Renewable polymers have become an important focus in next-generation materials, and algae biomass offers an environmentally low-impact feedstock that can serve multiple uses. This study aims to develop a scalable methodology for production of microalgae-based polyols for polyurethane synthesis from waste oils derived from algae biomass. Following separation of omega-3 fatty acids from algae oil, residual oils can offer valuable building blocks for petrochemical replacements. However, unlike vegetable oils, algae oils contain organic contaminants, including photosynthetic pigments and hydrophobic cofactors that can complicate preparative methodologies. Here we convert and purify waste streams from omega-3 depleted Nannochloropsis salina algae oil, with major components consisting of palmitic and palmitoleic acid, into azelaic acid (AA) as a building block for flexible polyurethanes, with a simultaneous production of heptanoic acid (HA) as a flavor and fragrance precursor. Conversion of free fatty acid mixtures into a soft soap allows extraction of organic contaminants, and urea complexation provides isolated palmitoleic acid, which is subsequently ozonolyzed to produce AA and HA. Bio-based polyester diols are prepared from AA via esterification to provide a polyol monomer for flexible polyurethane foam preparation. The HA co-product is modified to produce the flavoring agent methyl heptanoate and also decarboxylated to produce hexane as a renewable solvent. This scalable process can be performed on oils from multiple algal species, offering valuable monomers from a highly sustainable source.

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Biomass-Derived Polymeric Binders in Silicon Anodes for Battery Energy Storage Applications

The demand for portable electronic devices has increased rapidly during the past decade, and has driven a concordant growth in battery production. Since their development as a commercial energy storage solution in the 1990s, lithium-ion batteries (LIBs) have attracted significant attention in both science and industry due to their long cycle life, high energy density, low self-discharge rate, and high working voltage. Production of LIBs requires large amounts of a polymeric binder – commonly polyvinylidene difluoride (PVDF) – for processing and performance purposes. However, since this material is petrochemically-derived, it is far from “green” or sustainable. On the other hand, polymers and their building blocks are found widely throughout nature and can be renewably sourced from biomass at low cost; therefore, replacing PVDF with biomass-derived binders is a promising approach to reduce the environmental footprint of LIBs. Additionally, polymer binders play a critical role in next-generation battery performance. For instance, silicon (Si) is a promising high-capacity anode material for LIBs because of its high theoretical capacity (4200 mA h g –1 ), low working potential, and high abundance in Earth's crust. However, its huge volume change during charge/discharge tends to result in a shortened cycle life, since conventional binders interact only weakly with silicon's native surface and cannot maintain long-term integrity of the electrode. Naturally derived polymers have found better success in this role due to their high structural advantages. In this review, we summarize recent developments in silicon anode binders derived from various biomass sources, with a focus on polymer properties and their effect on battery performance. Further, we propose various perspectives based on our own assessment of these works, and provide a brief commentary on the future outlook of the field.

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Separation of alkane and alkene mixtures by metal–organic frameworks

The separation of alkane/alkene gas mixtures represents an important yet challenging process in the petrochemical industry to produce valuable chemical feedstocks with sufficiently high purity. These molecules have similar physical properties, making their separation difficult and capital-intensive. The current separation and purification technology relies largely on heat-driven distillations with a huge unit composed of hundreds of trays. Adsorptive separation using porous solids is capable of accomplishing the purification under ambient conditions, offering potential energy and environmental benefits. In particular, metal–organic frameworks (MOFs) hold enormous promise for this separation process in light of their highly tunable pore shape, pore size, and pore surface functionality. In this review article, we provide a comprehensive account of metal–organic frameworks that have been investigated for the separation of alkanes and alkenes with a focus on C 2 –C 3 hydrocarbons. Here, the material design rationale, separation mechanisms, and structure–property relations are highlighted. Finally, the existing challenges and possible design strategies for desirable materials are also discussed.

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Microporous metal–organic frameworks for the purification of propylene

Separation of propylene from its analogous hydrocarbons such as propane is of great importance in the petrochemical industry to produce valuable chemical feedstocks with desired purity. However, the well-established method currently used for industrial propane/propylene separation is energy intensive. It involves repeated cycling in the cryogenic and high-pressure distillation process and requires multiple columns and high reflux ratios because of the very similar physical properties of the two species. Thus, it is identified as one of the most capital- and energy-intensive processes. Adsorptive separation based on porous adsorbents is regarded as an alternative energy-efficient technology to replace or supplement the traditional heat-driven cryogenic distillation processes. In this context, metal–organic frameworks (MOFs) have emerged as the most promising candidates for propane/propylene separation, taking into consideration their unique tunability with respect to pore geometry and pore functionality. In this highlight, we summarize the latest advancement in developing MOFs as physisorbents for the separation and purification of propylene from propane, with a focus on those that demonstrate selective molecular exclusion and propane-selective adsorption. We discuss the adsorption preferences related to the material design and separation mechanisms, and review the existing challenges. Lastly, we offer our perspectives on various strategies for the future design of MOFs that hold true potential for propylene purification under industrial settings.

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Simultaneous removal of C 2 H 2 and C 2 H 6 for C 2 H 4 purification by robust MOFs featuring a high density of heteroatoms

Simultaneous removal of C 2 H 6 and C 2 H 2 from C 2 H 4 streams is of great importance in the petrochemical industry but remains a challenging task. To address this challenge, we have selected three isoreticular MOFs with high stability, low cost, and desirable scale-up ability, namely, MOF-303, MIL-160, and CAU-23 and assessed their potential in simultaneous removal of acetylene and ethane for ethylene purification. Each MOF exhibits desirable C 2 H 2 and C 2 H 6 uptake capacity (>5.5 mmol g –1 and >4 mmol g –1 , respectively), as well as good C 2 H 2 /C 2 H 4 selectivity (>2) and C 2 H 6 /C 2 H 4 selectivity (>1.5). Notably, MOF-303 takes up 4.96 mmol g –1 C 2 H 6 at 298 K and 1 bar, the highest value among the three MOFs, with C 2 H 6 /C 2 H 4 selectivity in the range of 1.55–2.47. MIL-160 possesses a very high C 2 H 2 uptake (9.1 mmol g –1 ) and C 2 H 2 /C 2 H 4 selectivity, 10.6 (1 : 1, v/v), at 298 K, much higher than those of all other MOFs tested to date for simultaneous removal of C 2 H 6 and C 2 H 2 from C 2 H 4 . The results from breakthrough experiments confirm that all three MOFs demonstrate excellent performance for C 2 H 4 purification in a ternary mixture of C 2 H 6 /C 2 H 4 /C 2 H 2 (1 : 1 : 1, v/v/v). Here, for MOF-303, MIL-160, and CAU-23, polymer-grade C 2 H 4 up to 0.164, 0.21, and 0.181 mmol g –1 can be obtained from the equimolar ternary mixture in a single separation step from the breakthrough experiment. Additionally, DFT calculations have been performed to further investigate the mechanism of adsorption/separation for C 2 H 6 , C 2 H 4 , and C 2 H 2 .

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Bioconversion of self-neutralized chemically depolymerized lignin streams into polyhydroxyalkanoates

Lignin is a chemically complex, diverse, and abundant plant polymer mainly composed of aromatic monomers. These aromatic monomers make lignin a potential source of aromatics and a viable substitute for petrochemically-derived aromatics. However, the structural recalcitrance of lignin requires harsh reagents from the chemical process and expensive catalysts for effective depolymerization. This chemical process often results in poor yields of chemical intermediate mixtures of varying bioavailability and/or toxicity. Furthermore, the cost of additional reagents required to separate or detoxify these intermediates makes processing lignin impractical. We report progress towards the use of such chemically depolymerized lignin streams by employing bacterial strains to produce polyhydroxyalkanoates (PHA). PHAs are a group of biodegradable microbial polyesters that have potential as a replacement for petroleum-based plastics. In this study we utilized two distinct lignin streams obtained after chemical depolymerization of lignin under alkaline and acidic pH in the presence of catalysts. We mixed the alkali-treated depolymerized stream with the acid-treated depolymerized stream to create a solution of neutral-pH chemically depolymerized lignin (CDL). We found moderate to substantial growth of both native and non-native PHA producers on the mixture of CDL as well as its aliphatic and aromatic components. PHA was detected by Sudan Black B staining in C. necator H16, P. putida KT2440, and E. coli LSBJ STQKAB grown on mixed CDL as the sole carbon source. For C. necator H16 and E. coli LSBJ STQKAB we found that PHA content was greater when grown on mixed CDL when compared to their preferred carbon source by GC-FID quantification. Our study provided progress towards a cost-competitive, sustainable, and industrially relevant use for lignin.

Winkler, Gordon L. W. [Univ. of Wisconsin, Madison↗

Evidence that Criegee intermediates drive autoxidation in unsaturated lipids

Significance Autoxidation leads to the slow persistent destruction of organic molecules causing oxidative stress and associated disease. The prevailing autoxidation mechanism of unsaturated lipids involves chain reactions initiated and propagated by H-atom abstraction, mediated by peroxy radicals and other reactive oxygen species. Here we report experimental evidence for an autoxidation mechanism initiated by OH, which is unanticipated and proceeds by OH addition followed by pathways involving Criegee intermediates (CIs). Although CIs are routinely encountered in atmospheric and synthetic organic chemistry, their role in autoxidation is unexpected. Our results suggest that in all likelihood these exotic species play a much more prominent and general role in the chemistry of cells, food, petrochemicals, and the environment beyond what is currently believed.

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