Frontiers of Chemical Science and Engineering最新文献

The efficient fractionation and recovery of monosaccharides (xylose and glucose) from lignocellulosic biomass facilitates subsequent sugar-based derivative production. This study introduces a one-pot γ-valerolactone/ CuCl₂ biphasic pretreatment system (100-mmol·L^-1 CuCl₂, 180 °C, 60 min) capable of achieving removal rates of 92.25% and 90.64% for xylan and lignin, respectively, while retaining 83.88% of cellulose. Compared to other metal chlorides (NaCl, LiCl, FeCl₃, and AlCl₃), the γ-valerolactone/CuCl₂ system recovered 121.2 mg·(g eucalyptus)^-1 of xylose and 55.96 mg·(g eucalyptus)^-1 of glucose during the pretreatment stage and 339.2 mg·(g eucalyptus)^-1 of glucose during the enzymatic hydrolysis stage (90.78% of glucose yield), achieving a total monosaccharide recovery of 86.31%. In addition, the recovery of γ-valerolactone was 79.33%, exhibiting minimal changes relative to the pretreatment performance. The method proposed in this study allows a high total monosaccharides recovery and a circular economy-oriented pretreatment approach, offering a viable pathway for biorefinery.

Electrocatalytic NO reduction reaction offers a sustainable route to achieving environmental protection and NH₃ production targets as well. In this work, a class of dealloyed Ti₆₀Cu₃₃Mn₇ ribbons with enough nanoparticles for the high-efficient NO reduction reaction to NH₃ is fabricated, reaching an excellent Faradaic efficiency of 93.2% at -0.5 V vs reversible hydrogen electrode and a high NH₃ synthesis rate of 717.4 μmol·h^-1·mg_cat.^-1 at -0.6 V vs reversible hydrogen electrode. The formed nanoparticles on the surface of the catalyst could facilitate the exposure of active sites and the transportation of various reactive ions and gases. Meanwhile, the Mn content in the TiCuMn ribbons modulates the chemical and physical properties of its surface, such as modifying the electronic structure of the Cu species, optimizing the adsorption energy of N* atoms, decreasing the strength of the NO adsorption, and eliminating the thermodynamic energy barrier, thus improving the NO reduction reaction catalytic performance. Moreover, a Zn-NO battery was fabricated using the catalyst and Zn plates, generating an NH₃ yield of 129.1 μmol·h^-1·cm^-2 while offering a peak power density of 1.45 mW·cm^-2.

Reactant gas and liquid water transport phenomena in the flow channels are complex and critical to the performance and durability of polymer electrolyte membrane fuel cells. The polymer membrane needs water at an optimum level for proton conductivity. Water management involves the prevention of dehydration, waterlogging, and the cell’s subsequent performance decline and degradation. This process requires the study and understanding of internal two-phase flows. Different experimental visualization techniques are used to study two-phase flows in polymer electrolyte membrane fuel cells. However, the experiments have limitations in in situ measurements; they are also expensive and time exhaustive. In contrast, numerical modeling is cheaper and faster, providing insights into the complex multiscale processes occurring across the components of the polymer electrolyte membrane fuel cells.

This paper introduces the recent design of flow channels. It reviews the numerical modeling techniques adopted for the transport phenomena therein: the two-fluid, multiphase mixture, volume of fluid, lattice Boltzmann, and pressure drop models. Furthermore, this work describes, compares, and analyses the models’ approaches and reviews the representative results of some selected aspects. Finally, the paper summarizes the modeling perspectives, emphasizing future directions with some recommendations.

The oxidative condensation between renewable furfural and fatty alcohols is a crucial avenue for producing high-quality liquid fuels and valuable furan derivatives. The selectivity control in this reaction process remains a significant challenge. Herein, we report the strategy of confining well dispersed gold species within ZSM-5 structure to construct highly active Au@ZSM-5 zeolite catalysts for the oxidative condensation of furfural. Characterization results and spectroscopy analyses demonstrate the efficient encapsulation of isolated and cationic Au clusters in zeolite structure. Au@ZSM-5(K) catalyst shows remarkable performance with 69.7% furfural conversion and 90.2% furan-2-acrolein selectivity as well as good recycle stability. It is revealed that the microstructure of ZSM-5 zeolite can significantly promote oxidative condensation activity through confinement effects. This work presents an explicit example of constructing zeolite encaged noble metal catalysts toward targeted chemical transformations.

Sodium-ion batteries (SIBs), which serve as alternatives or supplements to lithium-ion batteries, have been developed rapidly in recent years. Designing advanced high-performance layered Na_xTMO₂ cathode materials is beneficial for accelerating the commercialization of SIBs. Herein, the recent research progress on scalable synthesis methods, challenges on the path to commercialization and practical material design strategies for layered Na_xTMO₂ cathode materials is summarized. Co-precipitation method and solid-phase method are commonly used to synthesize Na_xTMO₂ on mass production and show their own advantages and disadvantages in terms of manufacturing cost, operative difficulty, sample quality and so on. To overcome drawbacks of layered Na_xTMO₂ cathode materials and meet the requirements for practical application, a detailed and deep understanding of development trends of layered Na_xTMO₂ cathode materials is also provided, including high specific energy materials, high-entropy oxides, single crystal materials, wide operation temperature materials and high air stability materials. This work can provide useful guidance in developing practical layered Na_xTMO₂ cathode materials for commercial SIBs.

Hydrogenolysis has been explored as a promising approach for plastic chemical recycling. Noble metals, such as Ru and Pt, are considered effective catalysts for plastic hydrogenolysis, however, they result in a high yield of low-value gaseous products. In this research, an efficient bimetallic catalyst was developed by separate impregnation of Ni and Ru on SiO₂ support resulting in liquid products yield of up to 83.1 C % under mild reaction conditions, compared to the 65.5 C % yield for the sole noble metal catalyst. The carbon distribution of the liquid products from low density polyethylene hydrogenolysis with Ni-modified catalyst also shifted to a heavier fraction, compared to that with Ru catalyst. Meanwhile, the NiRu catalyst exhibited excellent performance in suppressing the cleavage of the end-chain C–C bond, leading to a methane yield of only 10.4 C %, which was 69% lower than that of the Ru/SiO₂ catalyst. Temperature programmed reduction and desorption of hydrogen and propane were further conducted to reveal the detailed mechanism of low density polyethylene hydrogenolysis over the bimetallic catalyst. The results suggested that the Ni-Ru alloy exhibited stronger H adsorption properties indicating improved hydrogen coverage on the catalyst surface thus enhancing the desorption of reaction intermediates. The carbon number distribution was ultimately skewed toward heavier liquid products.

Nowadays, although functionalized pillararenes have been widely designed to be used in drug delivery system, targeted group modified pillararenes have been seldom reported and used in tumor multimodal therapy. Herein, a functionalized pillararene with a polyethylene glycol chain and triphenylphosphonium cation WP5-PEG-TPP was designed and synthesized. Subsequently, an active targeted drug delivery system was constructed based on its host-guest interactions with a newly designed porphyrin derivative, Py-Por. The experimental results demonstrated that this drug delivery system has exhibited excellent targeting ability against tumor cells, but interestingly it could not enter normal cells. After loading the hypoxia-activated prodrug tirapazamine, the prepared nanodrugs displayed high lethality to tumor cells due to their chemo/photodynamic synergistic therapy capability, but negligible toxicity to normal cells. Preliminary therapeutic mechanism study elucidated the synergistic therapy process.

Triboelectric nanogenerators (TENGs) are among the most promising available energy harvesting methods. Cellulose-based TENGs are flexible, renewable, and degradable. However, the flammability of cellulose prevents it from being used in open-flame environments. In this study, the lattice of cellulose was adjusted by the hydroxyl ionization of cellulose molecules, and Na⁺ was introduced to enhance the flame retardancy of cellulose nanofibers (CNFs). The experimental results showed that the amount of hydrogen bonding between cellulose molecules increased with the introduction of Na⁺ and that the limiting oxygen index reached 36.4%. The lattice spacing of cellulose increased from 0.276 to 0.286 nm, and the change in lattice structure exposed more hydroxyl groups, which changed the polarity of cellulose. The surface potential of the fibers increased from 239 to 323 mV, the maximum open-circuit voltage was 25 V·cm⁻², the short-circuit current was 2.10 µA, and the output power density was 4.56 µW·cm⁻². Compared with those of CNFs, the output voltage, current, and transferred charge increased by 96.8%, 517%, and 23%, respectively, and showed good stability and reliability during cyclic exposure. This study provides a valuable strategy for improving the performance of cellulose-based TENGs.

The advancement of heterogeneous catalysts incorporating metal clusters in the nanometric size range has garnered significant attention due to their extraordinary catalytic activity and selectivity. The detailed characterization and understanding of the atomic structure of these metal clusters within catalysts is crucial for elucidating the underlying reaction mechanisms. In the present study, a distinctive three-atom PdNi cluster, characterized by two Pd atoms at terminal positions and a central Ni atom, was synthesized over mordenite zeolite. The presence of atomic PdNi clusters within the eight-membered ring side pocket area was confirmed by multiple advanced analytical techniques, including magic-angle spinning nuclear magnetic resonance spectroscopy, synchrotron X-ray powder diffraction, extended X-ray absorption fine structure spectroscopy, and high-angle annular dark-field scanning transmission electron microscopy. The catalytic activity of the confined active species was examined by the carbene-mediated reactions of ethyl-2-diazoacetate to ethyl-2-methoxyacetate as a model reaction. Compared to the Pd-mordenite and Ni-mordenite, the PdNi-mordenite catalyst incorporates a PdNi cluster, which demonstrates a superior performance, achieving 100% conversion and high selectivity under the same reaction conditions. Our study elucidates the potential of constructing bimetallic clusters in zeolites, providing valuable insights for developing new heterogeneous catalysts applicable to a wide range of catalytic processes.

Ammonia is a vital component in the fertilizer and chemical industries, as well as serving as a significant carrier of renewable hydrogen energy. Compared with the industry’s principal technique, the Haber-Bosch method, for ammonia synthesis, electro/photocatalytic ammonia synthesis is increasingly recognized as a viable and ecofriendly alternative. This method enables distributed small-scale deployment and can be powered by sustainable renewable energy sources. However, the efficiency of electro/photocatalytic nitrogen reduction reaction is hindered by the challenges in activating the N≡N bond and nitrogen’s low solubility, thereby limiting its large-scale industrial applications. In this review, recent advancements in electro/photocatalytic nitrogen reduction are summarized, encompassing the complex reaction mechanisms, as well as the effective strategies for developing electro/photocatalytic catalysts and advanced reaction systems. Furthermore, the energy efficiency and economic analysis of electro/photocatalytic nitrogen fixation are deeply discussed. Finally, some unsolved challenges and potential opportunities are discussed for the future development of electro/photocatalytic ammonia synthesis.