Chemical Engineering and Processing-Process Intensification
·
2021
·
IF 4.237
Yuanyuan Wang,Lei Ni,Junjie Wang,Feng Xu,Juncheng Jiang,Zhiquan Chen,Gang Fu,Yong Pan
Microreactors have been widely used with advantageous of large specific surface area, excellent heat and mass transfer performance. In this paper, experimental and numerical study were carried out to analyze the thermal hazard associated with the synthesis of isopropyl propionate in a microreactor. In the experimental study, the effects of reaction temperature, catalyst amount, channel diameter and flow rate were investigated. The optimal condition was as follows: channel diameter 2 mm, amount of catalyst 0.8%, reactant ratio n(propionic anhydride): n(isopropanol) = 1:1, flow rate V (propionic anhydride + isopropanol) = 1 ml/min, and reaction temperature T = 60 °C. In this condition, the conversion of propionic anhydride reached 89.9% and the space–time yield was 2.39 × 10 6 mol m −3 h −1 . Computational Fluid Dynamics (CFD) technology was used to develop a model of the microreactor with this optimum condition. It showed that the flow rate of coolant and material of the microreactor had a great influence on the distribution of temperature. A lower cooling flow rate would lead to the formation of a heat transfer barrier in the cooling jacket. Under the same condition, a silicate glass microreactor had better heat transfer performance and was safer than other options.
研究领域:
化学工程
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反应工程
·
过程安全
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产品关联
DOI
高影响因子
JOURNAL OF MOLECULAR LIQUIDS
·
2024
·
IF 5.3
Hang Yao,Jialei Huang,Yuqing Ni,Gang Fu,Lei Ni,Juncheng Jiang,Yong Pan
Selection of appropriate solvents is of great significance for achieving efficient and safe m-xylene nitration . In this study, the exothermic behavior of m-xylene nitration under twelve organic solvents were studied by reaction calorimetry. The process hazards were assessed by calculation of thermal safety parameters. The reaction selectivity was quantified. The anhydrides exhibited the prominent promotion as water absorbent and active reagent in nitration, followed by selected aliphatic hydrocarbons, chlorinated hydrocarbons. While acetic acid, propionic acid and ethyl acetate had negative effects. The maximum yield of 95.6 % was achieved in nitric acid-acetic anhydride (HNO 3 -Ac 2 O) system. The thermal weight loss of the products appeared at around 150−230 °C by thermogravimetry experiments. The activation energy was determined to be 192.9 kJ/mol through adiabatic kinetic calculations. Furthermore, the solvent effects were analyzed by calculating the solvent polarity and its interaction energy with HNO 3 . The different action mechanisms of Ac 2 O and Pc 2 O on NO 2 + generation were revealed. The density functional theory calculations were in agreement with the experimental results. These findings can provide guidance for understanding of the solvent effect on the reaction hazards and selectivity of m-xylene nitration, and provide experimental and theoretical basis for solvent screening for the nitration of similar aromatic compounds.
研究领域:
化学工程
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理论化学
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产品关联
DOI
高影响因子
JOURNAL OF PHYSICAL CHEMISTRY B
·
2024
·
IF 2.8
Xingyu Wen,Wenshuai Bai,Dayu Zhang
The sulfuric–acid-catalyzed esterification reaction of 2-butanol and propionic anhydride is a vital industrial process. In this paper, several experiments are conducted via reaction calorimetry to validate that both sulfuric and propionic acids have discernible catalytic effects on the reaction. This finding complicates the accurate description of the reaction kinetics through traditional methods. So this paper turns to a kinetic-free black-box model, Gaussian process regression (GPR) model via 24 experiments, as a more adaptable approach. Besides, the best GPR model is combined with traditional heat balance model to generate a hybrid gray-box model, which can give complete knowledge of reaction process. The hybrid gray-box model finally achieves maximum root-mean-square error (RMSE) of 0.0069 for conversion, 0.6535 for temperature, and 10.6087 for heat flow rate, underscoring its pretty good predictive ability.
研究领域:
化学工程
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机器学习
·
反应动力学建模
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产品关联
DOI
PubMed
高影响因子
ACS Applied Materials & Interfaces
·
2024
·
IF 8.3
Jia Chen,Zhilin Chen,Xianbo Hou,Liming Chen
Efficient thermal insulators that can maintain their efficacy at extreme temperatures are in pressing demand, particularly in fields such as energy saving, aerospace, and sophisticated equipment. Herein, a novel and facile polymerization-regulated optimal strategy is adapted to realize the comprehensive performance of polyimide (PI) aerogel membranes with mechanical robustness, high flexibility, hydrophobicity, light transmittance, and efficient thermal insulation. Benefiting from the hydrolysis of monomers and chemical imidization reaction process verified by a thermo-chemo-mechanically coupled theoretical model, the viscosity of precursors, shrinkage rate, and microstructure of aerogels are precisely controlled, leading to a low thermal conductivity range of 0.023–0.044 W/(m·K). The fabricated PI aerogel membranes, which undergo a remarkable transformation from their initial brittle and opaque nature to a state of high flexibility and transparency, exhibit a 3.0 times increase in tensile strength (4.6 MPa) and a 8.4 times improvement in elongation at break (20.6%) over previous studies while demonstrating an exceptional light transmittance of 92.5% across a wide spectral range from 500 to 2500 nm. Additionally, the PI aerogel membranes possess superior mechanical properties and a wide temperature resistance range extending from −196 to 300 °C. These flexible PI aerogel membranes can be effectively adjusted to meet the practical application of a circular ring solar thermal collector, which displayed a high solar heat collection temperature of 135 °C at a thickness of 0.5 mm. The coordination between the thermophysical properties and mechanical properties of the PI aerogel membranes in this work holds great promise for application requirements of thermal insulators in optical elements under harsh environments.
研究领域:
材料科学
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能源工程
·
航空航天工程
✓ 已验证
产品关联
DOI
PubMed
高影响因子
INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
·
2024
·
IF 8.1
Dan Wang,Hanlin Wang,Juanjuan Fan,Hancheng Zhu,Akira Fujishima,Xintong Zhang
Photoelectrochemical (PEC) performance of photoanode is limited by the cascade-dynamic processes, mainly including light absorption , charge separation, and surface reaction. This work adopted a strategy of nanocones modification on FTO substrate (FTO-NC) to enhance light utilization and photoelectrons collection for improved PEC water splitting . Comparative studies showed that FTO-NC enhanced the light scattering, promoting the conversion process of photon to electron/hole and enlarging the effective surface area of BiVO 4 for surface reaction. Meanwhile, cooperative Mo-doping and Co-MOF decoration improved the bulk electron transportation in BiVO 4 , hole migration towards the electrode surface , and accelerated the water oxidation reaction of photogenerated holes. The photocurrent density of FTO-NC/BiVO 4 -Mo/MOFs reached 3.56 mA cm −2 , 6.14 times that of pristine BiVO 4 . The IPCE of FTO-NC/BiVO 4 -Mo/MOFs photoanode achieve 60% at 1.23 V vs. RHE, demonstrating a significantly enhanced light utilization performance. This work presents new insight into boosting cascade-dynamic processes through collaborative strategies for highly efficient PEC water-splitting.
研究领域:
材料科学
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能源科学
✓ 已验证
产品关联
DOI
高影响因子
INORGANIC CHEMISTRY
·
2025
·
IF 4.7
Miaomiao Chen,Huili Zhao,Han Xue,Yan Liang,Min Ji,Min Wang
B(C6F5)3-based frustrated Lewis pairs (FLPs) have made remarkable progress in metal-free catalytic reduction. However, the high affinity of B(C6F5)3 for oxygen makes it susceptible to irreversible poisoning when exposed to H2O, limiting its widespread application in reductive amination. To overcome the influence of H2O, a hydrophobic catalyst, B(C6F5)3@Rn–1-MIL-101 (n = 3, 5, 7), was developed by confining B(C6F5)3 within the nanocages of metal–organic frameworks (MOFs) modified with alkyl chains. The hydrophobic strength of the catalyst could be adjusted by varying the length of the alkyl chain. At n = 3, the alkyl chain was too short to be hydrophobic, while the excessively long alkyl chain blocked the pore channels and adversely affected the loading of B(C6F5)3 at n = 7. Only the catalyst B(C6F5)3@R4-MIL-101 synthesized at n = 5 could effectively facilitate the reductive amination of aldehydes or ketones with amines in a “wet solvent.” The strategy of combining hydrophobic MOFs with B(C6F5)3 to prepare heterogeneous catalysts for FLP catalysis not only provides a fresh avenue for investigating catalytic systems for reductive amination but also represents an innovative approach to advancing FLP chemistry.
研究领域:
化学
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催化科学
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产品关联
DOI
PubMed
高影响因子
JOURNAL OF APPLIED POLYMER SCIENCE
·
2024
·Vol. 141
·期 32
·e55759
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IF 2.7
Sizhao Zhang,Chun Liu,Zhao Wang,Jing Wang,Guangyu Xu,Hongwei Shi
Polyimide (PI) aerogels possess a rather potential in thermal protection material for aircraft, owing to their low thermal conductivity, high thermal stability, and low bulk density. However, the large shrinkage of pure PI aerogels is still a challenge in the complete preparation process. Herein, a kind of PI hybrid aerogel composite was prepared successfully by introducing polyurethane fiber as the reinforcing agent. The aerogel composite could realize the enhancement for the pure PI aerogels from a micro/macroscopic perspective, ultimately ensuring the ultralow shrinkage rate of 3.52%. Due to the inhibition of the shrinkage characteristic, the aerogel composite obtained achieved excellent thermal insulation, especially retaining a low temperature of 40.7°C despite the hot surface temperature reached up to 150°C. Besides, the lightweight low-density, exceptional flame resistance, and self-extinguishing properties were reflected from PI hybrid aerogel composite constructed, including the outstanding hydrophobic feature (water contact angle of 120°). The PI hybrid aerogel composite as prepared may be used for the thermal management of aircraft in a great measure, illustrating the feasible strategy of fabricating PI-based aerogel composites.
研究领域:
材料科学
·
航空航天工程
✓ 已验证
产品关联
DOI
高影响因子
Science Advances
·
2026
·Vol. 12
·期 13
·
IF 13.9
Taisong Fang,Songbai Liu
Efficient oral delivery of RNA to the target site is a long-standing issue for nucleic acid–based therapy. Herein, we adopted a vesicle-to-vesicle transfer strategy and established an efficient approach to encapsulate and stabilize RNA for targeted oral delivery. The amphiphilic specifically acylated epigallocatechin directly performed encapsulation of RNA and generated nanovesicles in high efficiency without assistance of additional materials. The RNA encapsulated in the nanovesicles was efficiently transferred to outer membrane vesicles (OMVs) derived from Escherichia coli Nissle 1917 probiotic through membrane fusion with simple operation. The derived hybrid vesicles (HVs) were further anchored with bilirubin and Lys-Asp-Glu-Leu grafted hyaluronic acid (HA-BR-KDEL) ligand for sequential cellular and intracellular targeting to the endoplasmic reticulum of inflammatory cells in inflamed intestinal tract. Oral delivery of HVs@HA-BR-KDEL notably alleviated colitis symptoms in mice and contributed to the restoration of intestinal homeostasis. The tea polyphenol hybrid OMV strategy holds great promise for oral gene-mediated treatment.
✓ 已验证
产品关联
DOI
高影响因子
CARBOHYDRATE POLYMERS
·
2012
·
IF 3.628
Yihao Luan,Jinming Zhang,Maosheng Zhan,Jin Wu,Jun Zhang,Jiasong He
Using 4-dimethylaminopyridine (DMAP) as the catalyst, highly efficient propionylation and butyralation of cellulose were successfully carried out in an ionic liquid 1-allyl-3-methylimidazolium chloride (AmimCl) under mild conditions. Cellulose propionate (CP) and cellulose butyrate (CB) with a degree of substitution (DS) in the range from 0.89 to 2.89 were synthesized within only 30 min at 30 °C. The DS values of the products could be well controlled just by molar ratio of acid anhydride/anhydroglucose unit (AGU). More interestingly, the conversions of acid anhydrides in both propionylation and butyralation were as high as above 90%, even 96%. Therefore, this work provides a facile and highly efficient way for the synthesis of cellulose esters CP and CB.
研究领域:
化学工程
·
材料科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
Gels
·
2025
·Vol. 11
·期 11
·929
·
IF 5.3
Mingkang Wang,Shuai Yu,Jing Wang,Xin Zhao,Changpeng Yang,Ran Wei,Chun Liu,Sizhao Zhang
Polyimide aerogels have garnered considerable attention due to their high-performance combination of a lightweight nature, low thermal conductivity, and high mechanical strength, which renders them ideal candidates for thermal insulators in aerospace. However, the inherent conflict in achieving multifunctional (dimensional stability and mechanical stiffness at high temperatures, and highly efficient thermal insulation) integration presents a great challenge. Here, we present an aerogel skeleton construction strategy based on hybridizing an Al–O network phase to create multifunctional polyimide aerogels. The resulting aerogels partially constructed by Al–O network phase exhibit an outstanding resistance to high temperatures (shrinkage of 0.56% after experiencing 200 °C for 2400 s), which is markedly superior to that of conventional polyimide aerogels. The excellent insulation capability of the aerogel is reflected in its low thermal conductivity (0.0214 W m −1 K −1 ) and its ability to maintain a cold-side temperature of just 59.7 °C under a 150 °C heat source. Furthermore, remarkable enhancements in mechanical properties are found at high-temperature conditions, providing evidence for the compressive stresses of 0.329 and 0.394 MPa under 3% strain at the respective temperatures of 200 and 250 °C, showing a clear trend of enhanced compressive stress with rising temperature. These advancements in high-temperature stability and mechanical properties substantially broaden the scope for their potential applications in aerospace thermal protection systems.
研究领域:
材料科学
·
航空航天工程
·
热防护系统
·
聚合物纳米复合材料
✓ 已验证
产品关联
DOI
PubMed
高影响因子
Polymers
·
2018
·Vol. 10
·期 3
·282
·
IF 2.935
Qiang Zhang,Xueqin Zhang,Ziyan Zhu,Aiping Zhang,Chunhui Zhang,Xiaoying Wang,Chuanfu Liu
Esterification is a versatile way to produce the derivatives of lignocellulose with developed properties. However, the traditional heterogeneous esterification of lignocellulose suffered from the drawbacks of low efficiency, additional reaction medium and heating. In the present study, an efficient method was developed to produce the functionalized sugarcane bagasse (SCB) by ball milling without any additional solvents and heating. The effects of pulverization time, rotation speed, the kind of linear chain anhydrides, the ratio of anhydrides to SCB, with or without pyridine catalyst and the dosage of catalyst were investigated on weight percent gain (WPG) of SCB esters. The results indicated that the high efficiency of this mechanocatalystic esterification was probably due to the destroyed crystalline structure and the promoted penetration of the esterifying reagent onto SCB bulk caused by ball milling. The maximumWPGof SCB acetate, propionate and butyrate reached 33.3%, 33.6% and 32.4%, respectively. The physicochemical structure of the esterified SCB was characterized with Fourier transform infrared spectra (FT-IR), solid state cross-polarized magic angle spinning13C nuclear magnetic resonance (CP/MAS13C-NMR), X-ray diffraction (XRD), scanning electron microscopy (SEM) and thermogravimetric analysis (TGA). The direct evidence of the esterification occurrence was provided with FT-IR and solid-state CP/MAS13C-NMR. The thermal stability of SCB increased upon the mechanocatalytic esterification. The results implied that the relatively homogeneous modification was achieved with this semi-homogeneous esterification method by ball milling.Keywords:sugarcane bagasse;esterification;ball milling;bio-based materials
研究领域:
生物质化学
·
材料科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
APPLIED THERMAL ENGINEERING
·
2020
·
IF 4.725
Qiang Chen,Lei Ni,Juncheng Jiang,Trent Parker,Zhiquan Chen,Zhen Cheng,Wei Jiang,Qingsheng Wang
Reaction inhibition is a promising option as an emergency measure to mitigate hazards caused by exothermic runaway reactions. The applications of phase change materials (PCMs) as inhibitors of runaway reactions have been influenced by thermal energy storage technologies. In this work, nano-PCMs powders with silica shells were fabricated using the sol–gel method at alkaline conditions. The prepared nano-PCMs had perfect core–shell microstructures and spherical morphologies, with an average encapsulated PCM particle diameter of 717.34 nm. In addition, the nano-PCMs exhibited high latent heats of fusion (129.1 J g −1 ), which could inhibit the uncontrolled self-heating caused by runaway reactions through conversion of the heats of reaction to the latent heats of PCMs. The homogeneous esterification of propionic anhydride with n -butanol catalyzed by sulfuric acid was chosen as target reaction with risk of exothermic runaway. Inhibition experiments was conducted in a batch reactor coupled with an in situ FTIR spectrometer. The heat transfer performance of reactant flow was studied to analyze the mechanism of thermal runaway inhibition with nano-PCMs. The results revealed that thermal runaway can be halted by applying nano-PCMs and that the reaction can proceed to completion steadily. The effect of Re on heat transfer performance was enlarged with addition of nano-PCMs. The enhancement in the heat transfer coefficient for PCM slurry was proved. Furthermore, the effectiveness of the thermal runaway inhibition can be significantly influenced by the warning temperature, stirring rate, and mass of added nano-PCMs. The applications of nano-PCMs for runaway reaction inhibition holds great potential for use in industrial processes.
研究领域:
化学工程
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）