Chem & Bio Engineering最新文献

Biomass is an abundantly available, underutilized feedstock for the production of bulk and fine chemicals, polymers, and sustainable and biodegradable plastics that are traditionally sourced from petrochemicals. Among potential feedstocks, 2,5-furan dicarboxylic acid (FDCA) stands out for its potential to be converted to higher-value polymeric materials such as polyethylene furandicarboxylate (PEF), a bio-based plastic alternative. In this study, the sustainable, electrocatalytic oxidation of stable furan molecule 2,5-bis(hydroxymethyl)furan (BHMF) to FDCA is investigated using a variety of TEMPO derivative electrocatalysts in a mediated electrosynthetic reaction. Three TEMPO catalysts (acetamido-TEMPO, methoxy-TEMPO, and TEMPO) facilitate full conversion to FDCA in basic conditions with >90% yield and >100% Faradaic efficiency. The remaining three TEMPO catalysts (hydroxy-TEMPO, oxo-TEMPO, and amino-TEMPO) all perform intermediate oxidation of BHMF in basic conditions but do not facilitate full conversion to FDCA. On the basis of pH studies completed on all TEMPO derivatives to assess their electrochemical reversibility and response to substrate, pH and reversibility play significant roles in the catalytic ability of each catalyst, which directly influences catalyst turnover and product formation. More broadly, this study also highlights the importance of an effective and rapid electroanalytical workflow in mediated electrosynthetic reactions, demonstrating how voltammetric catalyst screening can serve as a useful tool for predicting the reactivity and efficacy of a catalyst–substrate electrochemical system.

Dichloroethylene is mainly used to prepare high polymer compounds such as vinyl chloride fibers and polyvinylidene chloride. It is also an important raw material for producing lithium-ion battery adhesives. The industrial method for producing dichloroethylene involves a saponification reaction between trichloroethane and sodium hydroxide, which can lead to high environmental pollution. The 1,1,2-TCE (1,1,2-trichloroethane) catalytic cracking method has been widely studied due to its environmentally friendly potential to replace the saponification method. However, the low performance and stability of the catalysts have hindered the further development. The main reason is the lack of research on the intermediate processes of catalytic cracking. In this paper, in situ FTIR (Fourier transform infrared spectroscopy) and mass spectrometry combined technology was innovatively adopted to study the intermediate process of catalytic cracking of 1,1,2-TCE. In situ FTIR was used to analyze the generation of intermediate products, and online mass spectrometry was used to analyze the composition of exhaust gas. The formation of saturated steam from inert gas bubbling reactants in an in situ reaction pool could be used to investigate the microscopic reaction behavior of reactants on the catalyst surface in a macroscopic time system. The results indicated that 1,1,2-TCE produced residual products such as chloroacetylene and vinyl chloride during the dehydrochloride process. When 0.6 Cs/Al₂O₃ (activated alumina loaded with cesium chloride) was used as the catalyst, the dehydrochlorination of 1,1,2-TCE produced more chloroacetylene, reaching 4.62% at 533 K. When 0.6 Ba/Al₂O₃ (activated alumina loaded with barium chloride) was used as the catalyst, the dehydrochlorination of 1,1,2-TCE produced more vinyl chloride, reaching 6.54% at 533 K. Under the catalysis of 0.6 Cs/Al₂O₃, the initial cracking temperature of 1,1,2-TCE was 405 K, while under the catalysis of 0.6 Ba/Al₂O₃, the initial cracking temperature of 1,1,2-TCE was 450 K. The results revealed real-time changes in reactants and products during the reaction process, which was of great significance for catalyst screening, process condition selection, and research on the reaction mechanism.

Microorganisms, serving as super biological factories, play a crucial role in the production of desired substances and the remediation of environments. The emergence of 3D bioprinting provides a powerful tool for engineering microorganisms and polymers into living materials with delicate structures, paving the way for expanding functionalities and realizing extraordinary performance. Here, the current advancements in microbial-based 3D-printed living materials are comprehensively discussed from material perspectives, covering various 3D bioprinting techniques, types of microorganisms used, and the key parameters and selection criteria for polymer bioinks. Endeavors on the applications of 3D printed living materials in the fields of energy and environment are then emphasized. Finally, the remaining challenges and future trends in this burgeoning field are highlighted. We hope our perspective will inspire some interesting ideas and accelerate the exploration within this field to reach superior solutions for energy and environment challenges.

Separating natural gas to obtain high-quality C1–C3 alkanes is an imperative process for supplying clean energy sources and high valued petrochemical feedstocks. However, developing adsorbents which can efficiently distinguish CH₄, C₂H₆, and C₃H₈ molecules remains challenging. We herein report an ultra-stable layered hydrogen-bonded framework (HOF-NBDA), which features differential affinities and adsorption capacities for CH₄, C₂H₆, and C₃H₈ molecules, respectively. Breakthrough experiments on ternary component gas mixture show that HOF-NBDA can achieve efficient separation of CH₄/C₂H₆/C₃H₈ (v/v/v, 85/7.5/7.5). More importantly, HOF-NBDA can realize efficient C₃H₈ recovery from ternary CH₄/C₂H₆/C₃H₈ gas mixture. After one cycle of breakthrough, 70.9 L·kg^–1 of high-purity (≥ 99.95%) CH₄ and 54.2 L·kg^–1 of C₃H₈ (purity ≥99.5%) could be obtained. Furthermore, excellent separation performance under different flow rates, temperatures, and humidities could endow HOF-NBDA an ideal adsorbent for the future natural gas purification.

Transferring abundant, inexpensive, and nontoxic carbon dioxide (CO₂) into biodegradable polymers is one of the ideal ways to promote sustainable development. Although a great deal of preeminent researches has been reported in the last decade, including well-designed organometallic complexes, Lewis pairs, etc. The moisture- and air-sensitive nature of these extensively used catalysts preclude their use in industrial applications. Herein, we report a novel stable catalyst system of commercial zinc glutarate (ZnGA) with a supported metal for the synthesis of poly(ester-b-carbonate). The special supported microstructure facilitates efficient polymerizations via a plausible heterometal coordination mechanism. Notably, the resulted biodegradable CO₂-based copolymer showed strong tensile strength (>40 MPa), improved elongation (45% versus 7%), excellent transmittance, and low water vapor permeability (WVP) (1.7 × 10^–11 g m^–1 s^–1 Pa^–1). Moreover, the supported ZnGA catalyst is recyclable, and its simple and low-cost preparation process is compatible with the manufacturing and processing methods of the existing infrastructure.

In nature, biological systems can sense environmental changes and alter their performance parameters in real time to adapt to environmental changes. Inspired by these, scientists have developed a range of novel shape-morphing materials. Shape-morphing materials are a kind of “intelligent” materials that exhibit responses to external stimuli in a predetermined way and then display a preset function. Liquid crystal elastomer (LCE) is a typical representative example of shape-morphing materials. The emergence of 4D printing technology can effectively simplify the preparation process of shape-morphing LCEs, by changing the printing material compositions and printing conditions, enabling precise control and macroscopic design of the shape-morphing modes. At the same time, the layer-by-layer stacking method can also endow the shape-morphing LCEs with complex, hierarchical orientation structures, which gives researchers a great degree of design freedom. 4D printing has greatly expanded the application scope of shape-morphing LCEs as soft intelligent materials. This review systematically reports the recent progress of 3D/4D printing of shape-morphing LCEs, discusses various 4D printing technologies, synthesis methods and actuation modes of 3D/4D printed LCEs, and summarizes the opportunities and challenges of 3D/4D printing technologies in preparing shape-morphing LCEs.

Stimuli-responsive polymer materials are a kind of intelligent material which can sense and respond to external stimuli. However, most current stimuli-responsive polymers only exhibit a monotonic response to a single constant stimulus but cannot achieve dynamic evolution. Herein, we report a method to achieve a non-monotonic response under a single stimulus by regionalizing the crystallization and melting kinetics in semicrystalline polymers. Based on the influence of cross-linking on the crystallization and melting kinetics of polymers, we employ light to spatially regulate the cross-linking degree in polymers. The prepared material can realize the self-evolved encryption of pattern information and the non-monotonic shape evolution without complex multiple stimuli. By combination of pattern and shape evolution, the coupled encryption of shape and pattern can be achieved. This approach empowers polymers with the ability to evolve under constant stimulus, offering insights into the functional design of polymer materials.

Nepetalactol serves as the scaffold for most iridoids, which exhibit a wide range of biological and pharmacological activities. Iridoid synthase (ISY) plays a crucial role in the in vivo synthesis of nepetalactol from 8-oxogeranial. However, the substrate promiscuity of ISY could result in a deviation of flux toward off-target routes. In this work, the substrate preference (SP, the ratio of activity for 8-oxogeranial to geranial) of ISY for nepetalactol was improved by directed evolution. First, the strategy of focused polarity-steric mutagenesis scanning (FPSMS) was performed to construct a small mutant library with NmISY2 from Nepeta mussinii as an object. Four amino acid residues with varying polarity and steric hindrance, including alanine, aspartic acid, serine, and arginine, were incorporated to scan hot spots. Consequently, four sites of W109, M217, K343, and W345 with a significant impact on the substrate preference of NmISY2 were found. Then, the four sites were combined by a combinatorial active-site saturation test/iterative saturation mutagenesis (CAST/ISM) strategy. As a result, the mutant W345D/K343M/W109Y (3M+) was obtained with a significantly increased SP value for 6 from 8.5 to 293.1. Molecular dynamics simulations revealed that the steric hindrance and polarity of the substrate tunnel played pivotal roles in the SP value of NmISY2. Notably, upon integration of 3M+ into Pichia pastoris, the de novo titer of 6 increased by 24.9 times, reaching 15.8 mg/L. This study offers a strategic approach to improving the substrate preference of enzymes.

Reverse adsorption of carbon dioxide (CO₂) from acetylene (C₂H₂) presents both significant importance and formidable challenges, particularly in the context of carbon capture, energy efficiency, and environmental sustainability. In this Review, we delve into the burgeoning field of reverse CO₂/C₂H₂ adsorption and separation, underscoring the absence of a cohesive materials design strategy and a comprehensive understanding of the CO₂-selective capture mechanisms from C₂H₂, in contrast to the quite mature methodologies available for C₂H₂-selective adsorption. Focusing on porous materials, the latest advancements in CO₂-selective recognition mechanisms are highlighted. The review establishes that the efficacy of CO₂ recognition from C₂H₂ relies intricately on a myriad of factors, including pore architecture, framework flexibility, functional group interactions, and dynamic responsive behaviors under operating conditions. It is noted that achieving selectivity extends beyond physical sieving, necessitating meticulous adjustments in pore chemistry to exploit the subtle differences between CO₂ and C₂H₂. This comprehensive overview seeks to enhance the understanding of CO₂-selective recognition mechanisms, integrating essential insights crucial for the advancement of future materials. It also lays the groundwork for innovative porous materials in CO₂/C₂H₂ separation, addressing the pressing demand for more efficient molecular recognition within gas separation technologies.

Nature seamlessly integrates multiple functions for energy conversion, utilizing solar energy and salinity gradients as the primary drivers for ionic power generation. The creation of artificial membranes capable of finely controlling ion diffusion within nanoscale channels, driven by diverse forces, remains a challenging endeavor. In this study, we present an innovative approach: an ionic covalent-organic framework (COF) membrane constructed using chromophoric porphyrin units. The incorporation of ionic groups within these nanoconfined channels imparts the membrane with exceptional charge screening capabilities. Moreover, the membrane exhibits photoelectric responsivity, enhancing the ion conductivity upon exposure to light. As a result, this leads to a substantial increase in the output power density. In practical terms, when subjected to a salinity gradient of 0.5/0.01 M NaCl and exposed to light, the device achieved an outstanding peak power density of 18.0 ± 0.9 W m^–2, surpassing the commercial benchmark by 3.6-fold. This innovative membrane design not only represents a significant leap forward in materials science but also opens promising avenues for advancing sustainable energy technologies.