Reaction Chemistry & Engineering最新文献

In this study, we introduce a straightforward and effective strategy for synthesizing furfural directly from D-xylose and L-arabinose by employing hydrated iron(III) sulfate [Fe₂(SO₄)₃·xH₂O], under distillation at atmospheric pressure. The transformation proceeds without any organic solvent, using only pentose sugars derived from hemicellulose and 30 mol% of the catalytic agent. The process is optimized at a temperature of 170 °C. Under these conditions, after 90 minutes, D-xylose yields up to 92% furfural with 94% selectivity, while L-arabinose provides 85% yield with a selectivity of 90%. Water is the major by-product.

Developing efficient, durable, and low-cost bifunctional electrocatalysts is essential for renewable energy conversion. In this study, density functional theory (DFT) calculations are employed to systematically investigate Fe–N–O coordination structures anchored on graphene (Fe–N–O–gra), aiming to elucidate the structure–electronic–activity relationship in Fe-based single-atom catalysts. Among seven representative configurations, FeN₃O exhibits the highest structural stability, optimal orbital hybridization, and the largest charge transfer, thereby effectively facilitating O₂ activation. FeN₃O exhibits a longer Fe–O bond and weaker electronic coupling during *OH adsorption, which moderates intermediate binding in a step-specific way—facilitating *OH desorption in the ORR and stabilizing *OOH formation in the OER. This balance leads to exceptionally low overpotentials of 0.41 V for the ORR and 0.55 V for the OER, outperforming other configurations. Furthermore, a volcano plot constructed based on adsorption energy scaling relations identifies the *OH adsorption free energy as an effective descriptor of bifunctional catalytic activity, with FeN₃O located near the apex of the plot. These findings highlight the critical role of oxygen coordination in tuning the electronic structure and catalytic performance of Fe single-atom catalysts and provide theoretical guidance for the rational design of next-generation non-precious metal electrocatalysts.

Different types of sulfonated styrene resins (SSRs) were applied to the ethanolysis of furfuryl alcohol (FA) to ethyl levulinate (EL). The catalytic performance results showed that the SSR-2 catalyst prepared through sulfonation at 60 °C for 5 h demonstrated the best activity with 100% FA conversion and 97% EL selectivity under the reaction conditions of 126 °C, 2.2 h, and 0.12 g catalyst dosage, which was dramatically superior to the previous results. Notably, the SSR-2 catalyst maintained excellent stability over five cycles, which was attributed to the synergistic effect of the stable, three-dimensional crosslinked network structure of the styrene-based resins and the appropriate SO₃H groups, effectively alleviating the leaching problem of the active groups. Innovatively, Response Surface Methodology (RSM) was used to optimize the reaction conditions of FA ethanolysis over the SSR-2 catalyst and the catalyst dosage was identified as the most crucial factor for the production of EL, focusing on the effects of reaction temperature, reaction time and catalyst dosage on EL selectivity. Moreover, the predicted EL selectivity of 97.4% obtained from RSM matched well with the experimental value of 97% under the optimal reaction conditions, paving the way for catalyst engineering in EL production from FA ethanolysis.

Intermolecular photo-redox reactions can promote a wide range of chemical transformations. It is challenging to predict the photo-induced redox reaction for the intermolecular transfer of hydrogen and oxygen atoms. Herein, we have reported a strategy for transferring the intermolecular redox activity between nitroarenes and phenylmethylamines to make aromatic amines, aldehydes, and imines. The approach successfully synthesizes useful drug intermediates as well as final drug compounds, showcasing its efficiency and versatility. This protocol highlights significant practical utility in advanced organic synthesis.

Transient experiments provide a unique vantage point for heterogeneous catalysis, where the kinetic properties of complex industrial materials can be precisely characterized in a highly controlled manner. Dynamic variation of catalyst surface states and the changing response of chemical reactions can bring great insight, but these methods require complex analysis. Temporal Analysis of Products (TAP) is one such method, used to measure kinetic properties by separating the intrinsic reaction on a catalytic surface from the mass transport in the reactor using precisely controlled reactant pulsing under low pressure conditions. However, calculating intrinsic kinetic quantities from the exit flux measured in TAP experiments requires careful data analysis and/or modeling. In this paper, we demonstrate a virtual TAP reactor model (VTAP) that connects the observed exit flux with the reactor concentration profile and catalyst surface state evolving as a function of time. Simple adsorption processes and complex catalytic reactions are modeled and discussed. As kinetic quantities and number of active sites are changed, the presentation of distinct rate/concentration ‘fingerprints’ emerge that form the basis of benchmarking catalyst behavior. These reaction simulations are used to interpret experimental pulse response data collected on both simple, Pt/SiO₂, and complex, MoC_x/ZSM5, catalysts. The strategies for interpreting the reactor exit flux data to extract intrinsic and transient kinetics quantities using the VTAP model are discussed. Transport and reaction simulations supported by the VTAP model framework provide clear visualization of the unique reactor physics and catalyst dynamics, laying the groundwork for designing more informative experiments that advance industrial catalysis.

The effect of acid additives during transfer hydrogenolysis of aromatic ethers (lignin model compounds) in 2-propanol over a Ni catalyst was investigated. HCl, formic acid, and acetic acid, which have been typically used in organosolv lignin extraction, generally decreased the conversion of aromatic ethers and yields of monomers, indicating an inhibitory effect on transfer hydrogenolysis. Blank experiments demonstrated that acidity (proton release) was the primary reason for the inhibitory effect, but gaseous products from carboxylic acids were also a contributing factor. Comparison of acids revealed that the magnitude of inhibition followed the order HCl > formic acid > acetic acid, which corresponded to the order of their acid strength. Furthermore, the effect was discussed based on the potential proton concentration released from acid additives using their pK_a values.

Selective and efficient electrochemical analytical methods for examining the deposition of metallic aluminum are significant and necessary. Herein, the electrochemical behaviour of aluminium was studied at an inert tungsten electrode in an Na₃AlF₆–Al₂O₃–LiF–KF eutectic melt at 1253 K by means of transient electrochemical techniques. Electrochemical measurements are based on the potentiodynamic steady-state polarization curve plotting, continuous potential pulse method, constant potential method, constant current method and open-circuit chronopotentiometry. The cathodic overpotential for the deposition of metallic aluminum first decreased and then increased, while the activity of aluminum gradually decreased, as the cryolite ratio increased. Na⁺ ions discharged and precipitated when the cryolite ratio exceeded 3.0. KF played a decisive role in modifying electrode reactions, whereas the effect of LiF was not significant in the Na₃AlF₆–Al₂O₃–LiF–KF melt. The addition of KF not only influenced the current efficiency, but also affected the purity of the metallic aluminum, and the simultaneous addition of KF and LiF increased the dissolution loss of aluminum.

Alternating copolymerization of isobutylene (IB) and maleic anhydride (MAh) affords valuable isobutylene–maleic anhydride (IBMA) materials. But conventional stirred-tank processes in ethyl acetate are hindered by heterogeneous gas–liquid–solid behavior, sluggish mass transfer, and product precipitation, while DMF, offering potential homogeneity, performs poorly under mild batch conditions. Here, we use CFD-guided reaction process design and a high-pressure continuous-flow strategy to convert the system into a single-phase, homogeneous operation in DMF by selecting an appropriate solvent/temperature/pressure window and enforcing rapid micromixing. This process-intensified approach delivers minute-scale residence times and an up to 85% yield at 100–130 °C and 3.3 MPa, with controllable M_n between 8 and 20 kg mol⁻¹ and narrow dispersity. By comparison, the ethyl acetate system required 4 h to reach an 84.9% yield, while batch in DMF at 70 °C and 0.5 MPa afforded only 2.66%. The method offers a route to otherwise intractable alternating copolymerization of gaseous monomers and precipitation products, with advantages in safety, productivity, and scalability.

Polyamides, such as nylons, are often used in multi-component materials, like textiles and packaging, and are accompanied with unique recycling challenges. Recently, autoxidation and bioconversion has emerged as a tandem approach for the conversion of mixed plastics waste to single products, however the fate of polyamides in these processes is unknown. Here, we optimized the autoxidation of nylon-6 and nylon-6,6 depolymerization, achieving >92 mol% nitrogen recovery from both substrates, predominantly as acetamide, and 20–27 mol% carbon recovery (not including acetamide). Experiments with ¹³C-labeled acetic acid demonstrated that the carbon in acetamide was solvent derived. Autoxidation of mixed nylon-6 and poly(ethylene terephthalate) (PET) post-consumer fibers resulted in similar carbon and nitrogen recoveries from nylon, while PET was depolymerized to terephthalic acid (TPA) at >65 C-mol% recovery. Next, we engineered Pseudomonas putida KT2440 to utilize acetamide as the sole carbon and nitrogen source for growth through the constitutive expression of genes encoding amidase enzymes, including a native amidase (PP_0613) shown to be active on C₂–C₄ amides. Heterologous chromosomal expression of amiE, encoding the amidase from P. aeruginosa, was found to be superior to PP_0613 constitutive expression in genome integrated strains. Prior engineering to enable TPA conversion to β-ketoadipate pathway intermediate protocatechuate was leveraged and combined with deletion of pcaD to produce muconolactone as a product. Finally, a stacked strain engineered for conversion of acetamide, TPA, and DCAs was evaluated on the reaction product from autoxidation of mixed post-consumer nylon and PET fibers without any supplemental nitrogen, achieving quantitative yields in the presence of supplemental carbon.

Gold nanoparticles (AuNPs) have gained significant attention due to their applications in catalysis, sensing, electronics, diagnostics and therapeutics, necessitating scalable and reproducible production methods. Currently established protocols of the synthesis of AuNPs restrict up-scalability, thus preventing their industrialization into biomedical fields that could otherwise exploit their ground-breaking assets. This study explores a continuous hydrothermal process for the synthesis of AuNPs using gold trihydroxide (Au(OH)₃) as a chloride-free precursor, compatible with lab-made industrial-grade equipment. Batch synthesis was first used to determine optimal reaction conditions based on the Turkevich–Frens method, employing trisodium citrate as a reducing agent. These conditions were adapted to a continuous setup operating at high pressure (250 bar) and variable temperatures (100–400 °C). Under high pressure, well-dispersed AuNPs with different sizes and morphologies were successfully synthesized. Characterization of sizes, shapes and localized surface plasmon resonance confirmed successful particle formation and provided information about the dispersion state and optical properties. The system enabled steady AuNP production with minimal loss, demonstrating a promising route for scalable and controlled AuNP synthesis suitable for biomedical applications.