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The catalytic and targeted oxidation of monosaccharides into valuable sugar acids is a key reaction in the synthesis of biomass-based chemicals. Herein, an activated carbon supported gold catalyst was used to oxidize glucose and xylose to gluconic acid and xylonic acid under neutral condition with a flow-through reactor. Notably, the yields of gluconic and xylonic acid reach 93% and 92%, respectively. Moreover, we also explored the reaction kinetics including activation energ [Detail] ...
Download coverWith the advancement of social process, the resource problem is becoming more prominent, biomass materials come into being, and it is becoming more and more important to explore and prepare efficient and multifunctional biomass materials to alleviate the problems of energy storage and water pollution. In this paper, nitrogen-doped hierarchical porous carbon materials (NRRC) were produced by one-step carbonization of withered rose as raw material and melamine as nitrogen source with KOH-activated porosification. The resulting nitrogen-doped porous carbon material had the most abundant pores and the best microspherical graded pore structure, with a specific surface area of up to 1393 m2·g–1, a pore volume of 0.68 cm3·g–1, and a nitrogen-doped content of 5.52%. Electrochemical tests showed that the maximum specific capacitance of NRRC in the three-electrode system was 346.4 F·g–1 (0.5 A·g–1), which was combined with favorable capacitance retention performance and cycling stability. The NRRC//NRRC symmetric supercapacitors were further assembled, and the maximum energy density of a single device was 23.88 Wh·kg–1, which still maintains excellent capacitance retention and cyclic charging/discharging stability. For example, the capacitance retention rate was always close to 96.27% with almost negligible capacitance loss after 10000 consecutive charge/discharge cycles (current density: 10 A·g–1). Regardless of the three-electrode or two-electrode system, the super capacitive performance of NRRC porous carbon materials was comparable to the electrochemical performance of many reported biomass porous carbon materials, which showed better energy storage advantages and practical application potential. In addition, NRRC porous carbon materials had excellent water purification ability. The dye adsorption test confirmed that NRRC had a high adsorption capacity (491.47 mg·g–1) for methylene blue. This undoubtedly also showed a potential and promising avenue for high value-added utilization of this material.
NaA zeolite (Si/Al = 1.00) has been commercially applied for capturing radioactive 90Sr2+ because of its high surface charge density, effectively stabilizing the multivalent cation. However, owing to its narrow micropore opening (4.0 Å), large micron-sized crystallites, and bulkiness of hydrated Sr2+, the Sr2+ exchange over NaA has been limited by very slow kinetics. In this study, we synthesized nanocrystalline low-silica X by minimizing a water content in a synthesis gel and utilizing a methyl cellulose hydrogel as a crystal growth inhibitor. The resulting zeolite exhibited high crystallinity and Al-rich framework (Si/Al of approximately 1.00) with the sole presence of tetrahedral Al sites, which are capable of high Sr2+ uptake and ion selectivity. Meanwhile, the zeolite with a FAU topology has a much larger micropore opening size (7.4 Å) and a much smaller crystallite size (~340 nm) than NaA, which enable significantly enhanced ion-exchange kinetics. Compared to conventional NaA, the nanocrystalline low-silica X exhibited remarkably increased Sr2+-exchange kinetics (> 18-fold larger rate constant) in batch experiments. Although both the nanocrystalline low-silica X and NaA exhibited comparable Sr2+ capacities under equilibrated conditions, the former demonstrated a 5.5-fold larger breakthrough volume than NaA under dynamic conditions, attributed to its significantly faster Sr2+-exchange kinetics.
A novel carboxylated lactose/sodium lignosulfonate/polyacrylic acid hydrogel composites with self-reduction capacity was successfully synthesized by self-assembly method. The hydrogel with well-developed porous structure provided abundant anchoring points and reduction capacity for transforming Ag+ into silver nanoparticles. Silver nanoparticles dispersed among the network of hydrogel and the composites exhibited catalytic capacity. The catalytic performance was evaluated via degradation of p-nitrophenol, rhodamine B, methyl orange and methylene blue, which were catalyzed with corresponding reaction rate constants of 0.04338, 0.07499, 0.04891, and 0.00628 s–1, respectively. In addition, the catalyst exhibited stable performance under fixed-bed condition and the corresponding conversion rate still maintained more than 80% after 540 min. Moreover, the catalytic performance still maintained effective in tap water and simulated seawater. The catalytic efficiency still remained 99.7% with no significant decrease after 8 cycles.
Increasing global water shortages are accelerating the pace of membrane manufacturing, which generates many environmentally harmful solvents. Such challenges need a radical rethink of developing innovative membranes that can address freshwater production without generating environmentally harmful solvents. This work utilized the synthesized ultra-long hydroxyapatite (UHA) by the solvothermal method using the green solvent oleic acid in preparing UHA-based forward osmosis membranes. The membranes were developed using different loading ratios of graphene oxide (GO) by vacuum-assisted filtration technique. The prepared GO/UHA membranes were identified using X-ray diffraction, scanning electron microscope, Fourier-transform infrared spectroscopy, and X-ray photoelectron spectroscopy. Water contact angle and pore size distribution were determined for the obtained GO/UHA membranes. The obtained hierarchical porous structure in the prepared membranes with interconnected channels results in a stable water flux with reverse salt flux. The best water flux rate of 42 ± 2 L·m–2·h–1 was achieved using the 50 mg GO/UHA membrane, which is 3.3 times higher than the pristine membrane, and a reverse salt flux of 67 g·m–2·h–1. The obtained results showed a promising capability of a new generation of sustainable inorganic-based membranes that can be utilized in freshwater generation by energy-efficient techniques such as forward osmosis.
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·mgcat.–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.
Photothermal catalytic oxidation emerges as a promising method for the removal of volatile organic compounds (VOCs). Herein, via sol-gel impregnation method, spinel CuMn2O4 was coated on attapulgite honeycombs with integrating biochar (BC) film as the second carrier, using chestnut shell as complexation agent. Various mass ratios of CuMn2O4 to chestnut shell was modulated to investigate the catalytic toluene degradation performance. Results indicated that the monolithic CuMn2O4/BC/honeycomb catalyst demonstrated superior photothermal catalytic toluene degradation with a low T90 (temperature at 90% degradation) of 263 °C when the mass ratio of CuMn2O4 to biomass was 1:4. The addition of BC film substantially increased the honeycomb's specific surface area and improved the photothermal conversion of spinel, leading to enhanced photothermal catalytic activity. This study presents a cost-effective strategy for eliminating industrial VOCs using clay-biomass based monolithic catalyst.
The engineering of microbial cell factories for the production of high-value chemicals from renewable resources presents several challenges, including the optimization of key enzymes, pathway fluxes and metabolic networks. Addressing these challenges involves the development of synthetic auxotrophs, a strategy that links cell growth with enzyme properties or biosynthetic pathways. This linkage allows for the improvement of enzyme properties by in vivo directed enzyme evolution, the enhancement of metabolic pathway fluxes under growth pressure, and remodeling of metabolic networks through directed strain evolution. The advantage of employing synthetic auxotrophs lies in the power of growth-coupled selection, which is not only high-throughput but also labor-saving, greatly simplifying the development of both strains and enzymes. Synthetic auxotrophs play a pivotal role in advancing microbial cell factories, offering benefits from enzyme optimization to the manipulation of metabolic networks within single microbes. Furthermore, this strategy extends to coculture systems, enabling collaboration within microbial communities. This review highlights the recently developed applications of synthetic auxotrophs as microbial cell factories, and discusses future perspectives, aiming to provide a practical guide for growth-coupled models to produce value-added chemicals as part of a sustainable biorefinery.
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.
Photocatalytic CO2 reduction is a promising solution to simultaneously provide renewable chemical fuels and address the greenhouse effect. However, designing practical photocatalysts with advanced architectures remains challenging. Herein, we report the preparation of a novel CdIn2S4/TiO2 binary heterojunction via an in situ solvothermal approach, which exhibits superior photocatalytic activity for sunlight-driven CO2 reduction. The CdIn2S4/TiO2 composites exhibit significantly enhanced photocatalytic performance for CO2 reduction compared to unmodified TiO2. Among them, the 3% CdIn2S4/TiO2 composite has optimal CO and CH4 evolution rates of 18.32 and 1.03 μmol·g–1·h–1, respectively. The yield of CO is 4.7 times higher than that of pristine TiO2. This improved photocatalytic activity of the CdIn2S4/TiO2 heterostructure can be attributed to its large surface area, extended light absorption range and high separation efficiency of photogenerated electron-hole pairs, which are supported by the results of photoluminescence spectroscopy and the photoelectrochemical measurements. Moreover, the photocatalytic mechanism based on the binary CdIn2S4/TiO2 heterojunction is proposed and separation process of photogenerated electron-hole pairs is discussed. In brief, we aim to provide insights into the application of TiO2 in energy conversion processes through the construction of heterogeneous junctions.
A significant reaction in the synthesis of biomass-based chemicals is the catalyst-based and targeted oxidation of monosaccharides into valuable sugar acids. In this study, an activated carbon supported gold catalyst was used to oxidize glucose and xylose to gluconic acid and xylonic acid under neutral condition. Optimization of reaction conditions for the catalysts was performed using both a batch reactor and a flow-through reactor. In a batch reactor, the yields of gluconic and xylonic acid reached 93% and 92%, respectively, at 90 °C within 180 min. In a flow reactor, both reactions reached a similar yield at 80 °C with the weight hourly space velocity of 47.1 h–1. The reaction kinetics were explored in the flow reactor. The oxidation of glucose and xylose to gluconic and xylonic acid followed a first-order kinetics and the turnover frequency was 0.195 and 0.161 s–1, respectively. The activation energy was evaluated to be 60.58 and 59.30 kJ·mol–1, respectively. This study presents an environmentally friendly and feasible method for the selective oxidation of monosaccharides using an activated carbon supported gold catalyst, benefiting the high-value application of carbohydrates.
Genomic rearrangements play a crucial role in shaping biological phenotypic diversity and driving species evolution. Synthetic chromosome rearrangement and modification by LoxP-mediated evolution (SCRaMbLE) has been applied to explore large-scale genomic rearrangements, yet it has been observed that these rearrangements occur exclusively in genomic regions containing loxPsym sites. Here, we found that SCRaMbLE of synthetic yeast harboring synthetic chromosome V and X can generate a variety of synthetic segment insertions into wild-type chromosomes, ranging from 1 to 300 kb. Furthermore, it was revealed that the novel insertions impacted the transcriptional level of neighboring regions and affected the production of exemplar pathway of zeaxanthin. Collectively, our results improve the understanding of the ability of SCRaMbLE to generate complex structural variations in nonsynthetic regions and provide a potential model to explore genomic transposable events.
The cost-effective separation of ethylene (C2H4), ethyne (C2H2), and ethane (C2H6) poses a significant challenge in the contemporary chemical industry. In contrast to the energy-intensive high-pressure cryogenic distillation process, zeolite-based adsorptive separation offers a low-energy alternative. This review provides a concise overview of recent advancements in the adsorptive separation of C2H4, C2H2, and C2H6 using zeolites or zeolite-based adsorbents. It commences with an examination of the industrial significance of these compounds and the associated separation challenges. Subsequently, it systematically examines the utilization of various types of zeolites with diverse cationic species in such separation processes. And then it explores how different zeolitic structures impact adsorption and separation capabilities, considering principles such as cation-π interaction, π-complexation, and steric separation concerning C2H4, C2H2, and C2H6 molecules. Furthermore, it discusses methods to enhance the separation performance of zeolites and zeolite-based adsorbents, encompassing structural design, modifications, and ion exchange processes. Finally, it summarizes current research trends and future directions, highlighting the potential application value of zeolitic materials in the field of C2H4, C2H2, and C2H6 separation and offering recommendations for further investigation.
