Green Chemistry最新文献

Li-rich Mn-based layered oxides provide a compelling amalgamation of high theoretical capacity and cost-effectiveness, positioning them as prime contenders for next-generation lithium-ion battery cathodes. However, their vulnerability to surface instability gives rise to a host of challenges, notably severe capacity and voltage fading. Consequently, the surface modification of Li-rich Mn-based layered oxides emerges as a viable solution to tackle this issue. Nevertheless, current methods exhibit various drawbacks, encompassing time-intensive procedures, environmental unfriendliness, and challenges in scalability. Hence, we present a technique employing ultrafast high-temperature heating technology to dynamically reshape the chemistry and structure of the surface of individual single-crystal Li_1.2Mn_0.54Ni_0.13Co_0.13O₂ cathode particles (LMLO) within a rapid 8-second timeframe. Structural analysis reveals the seamless integration of the spinel structure onto the surface, intricately linked to the internal layered structure, accompanied by a notable abundance of oxygen vacancies. Leveraging the distinctive features of this modified structure, the material demonstrates enhanced discharge capacity, superior rate performance, and prolonged cycling stability compared to the unmodified counterpart. Significantly, in stark contrast to alternative preparation methods, this technique accomplishes the formation of the protective layer within a mere 8 seconds, showcasing unparalleled efficiency. Furthermore, it boasts safety and environmental friendliness, necessitates basic instrumentation, boasts ease of operation, and is well-suited for large-scale adoption. Consequently, this method is positioned to drive the commercialization of Li-rich Mn-based layered oxide cathode materials.

Various excellent catalysts have been explored for the methanolysis of polycarbonate (PC), but it is still challenging to develop green and economical catalysts for solvent-free PC methanolysis to recover both bisphenol A (BPA) and dimethyl carbonate (DMC). Herein, green, efficient and solvent-free degradation of PC to BPA and DMC was achieved using urea as a cheap green catalyst. At 140 °C for 3 h, PC was completely degraded to BPA and DMC with yields of 93.4% and 74.7%, respectively. A possible catalytic degradation mechanism of PC was proposed by kinetic experiments and NMR, where urea, methanol and carbonate formed a six-membered ring in the reaction. It was found that the increase of urea concentration significantly reduced the activation energy, which was attributed to the fact that the increase of urea concentration made the six-membered ring easier to form and activated the carbonate bond. The degradation system can be reused directly up to 10 times and 100% degradation rate can be maintained. This work provides a simple, green and economical method for industrial PC recycling.

In conjunction with the pressing global issue of climate change and the associated concern over global warming, increasing interest has emerged in the exploration of carbon dioxide (CO₂) as a resource for the generation of a diverse array of products intended to serve societal needs. This study presents the development of an ATP-free and NAD-balanced in vitro synthetic enzymatic biosystem (ivSEB), which comprises only five cascade thermophilic enzymes, designed for the synthesis of l-malate through CO₂ fixation powered by the utilization of d-glucose as a substrate. This designed ivSEB yields two moles of l-malate from one mole of d-glucose and two moles of CO₂. Through meticulous refinement of reaction conditions and enzyme loading amounts, this ivSEB has demonstrated its capability to produce 6.85 mM of l-malate via CO₂ fixation from an initial 5 mM of d-glucose with a molar product yield of 68.5%, and 2.45 mM of l-lactate as a byproduct. In the pursuit of assessing the industrial feasibility of this ivSEB, the study further subjected the system to the utilization of a high concentration (45.70 mM) of d-glucose. Although this endeavor necessitates additional optimization for enhanced efficiency, the present findings herald the emergence of an alternative avenue for the sustainable production of l-malate through CO₂ fixation, thus bearing substantial promise for addressing ecological and industrial imperatives.

High-quality liquid biofuels can be produced from renewable lignin-derived phenolic compounds through an efficient hydrodeoxygenation (HDO) process in which the traditional catalysts usually include metal sites and acid sites that catalyze the hydrogenation and deoxygenation procedures respectively. This work presents a novel acid-free Ni_xMo_yN/C catalyst from the perspective of green chemistry providing a new pathway for HDO of lignin-derived phenolic compounds that involves hydrogenation deoxygenation and hydrogenolysis at the same time. A series of Ni_xMo_yN/C catalysts were prepared by varying the Ni : Mo molar ratio among which the Ni₁Mo₃N/C catalyst showed the best HDO performance. Guaiacol could be completely converted at 260 °C after 4 h with 95.8% cyclohexane selectivity. In addition a small amount of benzene could be obtained as a valuable fuel additive by-product by altering the conventional HDO reaction path. By shortening the reaction time benzene could be obtained as an intermediate product with a relative high selectivity. Based on the characterizations using XRD BET SEM TEM XPS H₂-TPD and EPR, the results demonstrate that the multiple active components of the Ni₁Mo₃N/C catalyst allow it to efficiently catalyze the hydrogen activation and C–O bond cleavage even under acid-free conditions. The existence of the active phases of Ni Ni₂Mo₃N and β-Mo₂C as well as the interaction between Ni and Mo metals together contributed toward efficient HDO performance. Not only for the various phenolic model compounds the feasibility of Ni₁Mo₃N/C catalysts for upgrading raw lignin oil was also demonstrated with the hydrocarbon content increasing from 5.7% to 88.4%. Notably arenes accounted for 18.2% of the hydrocarbon products which confirmed the occurrence of hydrogenolysis in the catalytic process. This work provides a novel route for the conversion of lignin-derived phenolic compounds to produce high-quality hydrocarbon liquid biofuels especially the direct production of arene components.

Herein, an operationally simple and mild protocol for defluorinative alkylation and arylation between thianthrenium salts and α-trifluoromethyl alkene with visible light to afford gem-difluoroolefins has been developed. The main feature of this method is avoiding the use of a metal photocatalyst, and an organic photocatalyst is unnecessary for the arylation reaction. In addition, thianthrene can also be recycled and transformed to thianthrenium salts without affecting the efficiency of these reactions. The protocol demonstrates excellent tolerance of functional groups and viable functionalization of late-stage natural products and pharmaceutically relevant molecules.

A [4 + 1] annulation protocol is developed for the synthesis of various 2-alkenylindole derivatives starting from aminobenzyl phosphonium salts and cinnamaldehydes. In this process, the reaction proceeds efficiently without the usage of any metal catalysts or base, and features available starting materials, a broad substrate scope, excellent yields and simple reaction conditions.

Lignin is the main component of plant cell walls, conferring upon lignocellulosic biomass both excellent mechanical and barrier properties. At the same time, the considerable number of unsaturated groups and conjugated structures present in lignin render it a promising candidate for applications in the optical domain. In recent years, the development of the optical properties of lignin and lignin-derived optical materials has paved the way for a novel avenue of lignin valorization. This review is concerned with the mechanisms of lignin-derived optical materials, with particular emphasis on the physical and chemical structures that are linked to their optical performance, including UV absorption, photothermal conversion, and photoluminescence. Additionally, the potential applications of these materials in energy storage, bioimaging, structural materials, and photonic crystal are also presented, demonstrating the unique optical properties of lignin. Finally, the challenges and future directions of lignin as an optical material are presented, with the objective of developing lignin into a polymer biobased raw material that can serve advanced emerging industries.

Effective use of quantitative metrics is fundamental to guiding innovation toward more sustainable chemicals. At present, metrics employed in Green Chemistry, such as the E-factor, Process Mass Intensity, or Energy Intensity, focus on mass or energy efficiency at specific levels – reaction, process, or plant. However, a more holistic approach is needed, especially at early stages of research and development, utilising more complex impact-based indicators from Life Cycle Assessments (LCAs) to gain a deeper understanding of the environmental footprint of chemical systems. To date, the need to couple mass- and energy-based process metrics with life cycle impacts for more comprehensive assessments has been qualitatively discussed but not quantitatively demonstrated. Therefore, this study quantifies the level of correlation and linkages between five mass- and energy-based metrics and 16 LCA indicator scores by leveraging data for over 700 chemical manufacturing processes. The primary finding is the weak correlations between process metrics and life cycle impacts, as the former approach lacks appropriate weights for each input and output to account for their life cycle environmental implications. While improving process efficiency can lead to lower overall environmental impact, enhanced granularity for comparing alternative chemical routes provides insights into the relative impact levels throughout the supply chain, particularly concerning raw materials as they are major contributors to life cycle environmental impacts. This study also provides practical insights for expanding the application of LCA by making it more accessible to the research community through simplified approaches and working collaboratively with LCA practitioners.