A correct and timely fault diagnosis is important for improving the safety and reliability of chemical processes. With the advancement of big data technology, data-driven fault diagnosis methods are being extensively used and still have considerable potential. In recent years, methods based on deep neural networks have made significant breakthroughs, and fault diagnosis methods for industrial processes based on deep learning have attracted considerable research attention. Therefore, we propose a fusion deep-learning algorithm based on a fully convolutional neural network (FCN) to extract features and build models to correctly diagnose all types of faults. We use long short-term memory (LSTM) units to expand our proposed FCN so that our proposed deep learning model can better extract the time-domain features of chemical process data. We also introduce the attention mechanism into the model, aimed at highlighting the importance of features, which is significant for the fault diagnosis of chemical processes with many features. When applied to the benchmark Tennessee Eastman process, our proposed model exhibits impressive performance, demonstrating the effectiveness of the attention-based LSTM FCN in chemical process fault diagnosis.

The oxygen transportation from surrounding air to coating cracks is an important factor in the oxidation and ignition of titanium alloy. In this work, the oxygen transport and surface oxidation of titanium in inclined cracks of coating under parallel airflow are studied with the lattice Boltzmann method (LBM). A boundary scheme of LBM about surface reaction is developed. The conversion factors are utilized to build the relationship between the physical scale and the lattice scale. The reliability of the LBM model is validated by the finite element method (FEM). The results show that the convective mass transport driven by the surrounding airflow and the vortex structure formed inside the crack are the two significant factors that influence the oxygen transport in cracks. The convective mass transfer plays a major role in oxygen transport when the inclination angle of the crack is small. For the cases with a large inclination angle, the oxygen transfer from the top to the bottom of the crack is mainly controlled by mass diffusion mechanism. The oxygen concentration in inclined cracks is generally less than that in vertical cracks, and oxidation and ignition of the substrate titanium might be more likely to occur in relatively vertical cracks.

Solid oxide fuel cells (SOFCs) that operate at intermediate temperatures of 600 to 800 ℃ have recently received increased attention due to their improved durability, more rapid startup and shutdown, better sealing and lower cost than their counterparts operate at high temperatures. Nevertheless, intermediate-temperature SOFCs (IT-SOFCs) with popular perovskite cathodes contain alkaline-earth elements, which are prone to reaction with carbon dioxide (CO₂), even when the CO₂ content is comparatively low. In this work, an alkaline-earth metal-free Ruddlesden–Popper oxide, Nd_1.8La_0.2Ni_0.74Cu_0.21Ga_0.05O (NLNCG), is developed for IT-SOFC cathodes. The cell is based on an electrolyte with 8% (mol) Y₂O₃-stabilized ZrO₂ (8YSZ). The NLNCG cathode exhibits an excellent CO₂ tolerance, as proven by thermogravimetry analysis, in situ X-ray diffraction, I-V-P test, and electrochemical impedance spectroscopy (EIS), and stability measurements. The anode-supported single-cell NiO-YSZ|YSZ|NLNCG outputs a peak power density of 0.522 W·cm^-2 at 800 ℃. These findings suggest that NLNCG could be a highly suitable cathode material with CO₂ tolerance for IT-SOFCs.

Desalination is considered a viable method to overcome the issue of water scarcity either from waste water or seawater. For this purpose, this study employed a facile approach to develop surface immobilized oxidized-MWCNTs (o-MWCNTs) onto crosslinked polyvinyl alcohol (PVA) membrane. Firstly, modified polysulphone substrate was synthesized on to which crosslinked PVA layer was spread onto it. PVA layer act as active layer for surface immobilization of o-MWCNTs in varying concentration. The functional group analysis, morphology and roughness of membranes surface was conducted out using FTIR, SEM and AFM respectively. The results showed that modified membranes, immobilized o-MWCNTs enhanced the salt rejection (Na₂SO₄) upto 99.8%. After contacting with Escherichia coli and Staphylococcus aureus for 2.5 h the bacteria mortalities of the fabricated membrane could reach 96.9%. Furthermore, the anti-biofouling tests showed that OP-MWCNTs (1–5) modified membranes have higher anti-biofouling property than the control membrane.

Air pollution control poses a major problem in the implementation of municipal solid waste incineration (MSWI). Accurate prediction of nitrogen oxides (NO_x) concentration plays an important role in efficient NO_x emission controlling. In this study, a modular long short-term memory (M-LSTM) network is developed to design an efficient prediction model for NO_x concentration. First, the fuzzy C means (FCM) algorithm is utilized to divide the task into several sub-tasks, aiming to realize the divide-and-conquer ability for complex task. Second, long short-term memory (LSTM) neural networks are applied to tackle corresponding sub-tasks, which can improve the prediction accuracy of the sub-networks. Third, a cooperative decision strategy is designed to guarantee the generalization performance during the testing or application stage. Finally, after being evaluated by a benchmark simulation, the proposed method is applied to a real MSWI process. And the experimental results demonstrate the considerable prediction ability of the M-LSTM network.

The feasibility for natural graphite (NG) to replace artificial graphite (AG) in organic electrolytes with different additives are investigated. Although the strong film-forming additives contributes to form robust solid electrolyte interphase (SEI) film on graphite particle surface, great differences in gas evolution, lithium inventory loss and other side reactions are observed. Lithium bis(oxalato)borate (LiBOB) and fluoroethylene carbonate (FEC) are found more effective and the combination shows to be more promising. In the optimized electrolyte, natural graphite anode exhibits excellent long-term cycling capability. After 800 cycles at high temperature, the capacity retention is comparable to that using artificial graphite. The mechanisms for the capacity-fading of the full cells with AG and NG anode are investigated by ICP, SEM and polarization studies. The results shows that NG electrode consumes more active lithium due to the rough surface and larger volume expansion. The rapid capacity-fading in the initial 100 cycles is related to the instability of the SEI film aroused from large volume expansion. The systematic analysis is inspiriting for the development of high performance lithium ion batteries with reduced cost.

Humidity can affect the attenuation of MEA (membrane electrode assembly), however, the relationship between humidity and MEA decays is complex and ambiguous in realistic application. Herein, we design a simulating automotive protocol, performed on five single fuel cells under RH (relative humidity) 100%, RH 80%, RH 64%, and RH 40%, RH 10%, respectively, to study the relationship of MEA decays and humidity and suggest optimized humidity range to extend the durability. With the electrochemical impedance spectroscopy, cyclic voltammetry, X-ray fluorescence, X-ray diffraction, transmission electron microscope, X-ray photoelectron spectroscopy, the four degradation mechanisms about catalyst layer, including Pt dissolution, Pt coarsening, carbon corrosion and ionomer degradation, are observed. Pt coarsening and carbon corrosion are accelerated by higher water content at high humidity. Ionomer degradation and Pt dissolution are enhanced in low humidity. With the linear sweep voltammetry, ion chromatography, nuclear magnetic resonance, tensile test and scan electron microscope, chemical and mechanical degradation in proton exchange membrane are all observed in these five fuels. Chemical degradation, characterized by membrane thinning and more fluoride loss, occurred markedly in RH 10%. Mechanical degradation, characterized by the non-uniformity thickness and bad mechanical properties, is more pronounced in RH 100%, RH 80%, RH 64%. These two degradations are in a moderate level in RH 40%. The research suggests that the RH range from 64% to 40% is conductive to mitigate the degradation of MEAs operated in automotive applications.

There have been many studies on life cycle assessment in sewage treatment, but there are scarce few studies on the treatment of industrial wastewater in combination with advanced oxidation technology, especially in catalytic wet air oxidation (CWAO). There are no cases of using actual industrialized data onto life cycle assessment. This paper uses Simapro 9.0 software to establish a life cycle assessment model for the treatment of high-concentration organic wastewater by CWAO, and comprehensively explains the impact on the environment from three aspects: the construction phase, the operation phase and the demolition phase. In addition, sensitivity analysis and uncertainty analysis were performed. The results showed that the key factors affecting the environment were marine ecotoxicity, mineral resource consumption and global warming, the operation stage had the greatest impact on the environment, which was related to high power consumption during operation and emissions from the treatment process. Sensitivity analysis showed that electricity consumption has the greatest impact on abiotic depletion and freshwater aquatic ecotoxicity, and it also proved that global warming is mainly caused by pollutant emissions during operation phase. Monte Carlo simulations found slightly higher uncertainty for abiotic depletion and toxicity-related impact categories.

Traditional fluorescence switching molecules achieving the state change between on and off states commonly based on UV irradiation. However, it is worth noting that UV irradiation is harmful to both the cancer cells and the normal cells. To achieve fluorescence switching under visible wavelength and avoid complicate molecular design, a fluorophore of 2,4,5,6-tetrakis(carbazol-9-yl)-1,3-dicyanobenzene (4CzIPN) and a quencher of diarylethene (DAE) were physically incorporated within the biocompatible block copolymer poly(lactic-co-glycolic acid)-b-poly(ethylene glycol) (PLGA-b-PEG) to form 4CzIPN-DAE nanoparticles (NPs) through flash nanoprecipitation (FNP). By using the FNP method, the NPs were prepared within milliseconds in a confined impingement jets dilution (CIJ-D) mixer. Quenching and recovery of fluorescence could achieve in the presence of DAE under 475 nm and 560 nm irradiation. Appropriate structure and fluorescent properties of the nanoparticles can be tuned by external conditions for their efficient fluorescence resonance energy transfer (FRET) in a kinetic stabilization process. This NPs formation process was further optimized by varying the dilution ratio, Reynolds number (Re) and polymer concentration to modulate the mixing and particle nucleation and growth process. The size and fluorescence switching properties of the NPs were systematically investigated in solution and in cellular uptake experiments. This work is anticipated to provide a simple and highly effective engineering strategy for the modulation of fluorescence switching nanoparticles and beneficial to its engineering application.

Biochar is a well-known material for pollutant removal owing to its low cost and rich surface functionality. A kind of highly active substance, called environmentally persistent free radicals (EPFRs), can be produced in the preparation process of biochar, playing an important role in the removal of pollutants. In this study, sludge-derived biochars (SBC₁₂₀ and SBC₂₇₀) were prepared by the hydrothermal carbonization under two temperatures (120 ℃ and 270 ℃) to investigate their removal abilities of Cr(VI). The maximum removal amounts of Cr(VI) by SBC₁₂₀ and SBC₂₇₀ were 16.58 and 22.93 mg·g^-1, respectively. It was further revealed that the appearance of Cr(III), as a result of EPFRs on sludge-derived biochar (SBC) transferred electrons to Cr(VI) in neutral solutions. That is to say, oxygen-centered (O-centered) EPFRs on SBC₁₂₀ and carbon-centered (C-centered) EPFRs on SBC₂₇₀ all could be used as electron donors to Cr(VI) to make it become Cr(III). This study not only provides a theoretical basis for the mechanism of pollutants removal by sludge-derived biochar but also offers a new perspective on the direct effect of EPFRs on pollutants.

A novel process monitoring method based on convolutional neural network (CNN) is proposed and applied to detect faults in industrial process. By utilizing the CNN algorithm, cross-correlation and autocorrelation among variables are captured to establish a prediction model for each process variable to approximate the first-principle of physical/chemical relationships among different variables under normal operating conditions. When the process is operated under pre-set operating conditions, prediction residuals can be assumed as noise if a proper model is employed. Once process faults occur, the residuals will increase due to the changes of correlation among variables. A principal component analysis (PCA) model based on the residuals is established to realize process monitoring. By monitoring the changes in main feature of prediction residuals, the faults can be promptly detected. Case studies on a numerical nonlinear example and data from two industrial processes are presented to validate the performance of process monitoring based on CNN.

Oriented immobilization of enzymes helps to maintain their native structure and proper orientation for high-performance engineering to meet extensive biocatalysis demands. However, the supporting materials used for orientated immobilization are usually costly or complicated in preparation, affecting their practical applications. In this work, a facile purification and immobilization method was proposed for enzyme immobilization based on organic–inorganic hybrid calcium phosphate nanocrystal (CaPs) induced by Cu²⁺ modified bovine serum albumin (BSA-Cu). Then, the as-prepared hybrid calcium phosphate nanosheet, BSA-Cu@CaPs, was utilized for one-pot purification and immobilization of His-tagged organophosphorus hydrolase (OPH) by metal-affinity binding to the incorporated BSA. BSA-Cu@CaPs-OPH exhibited enhanced pH stability and thermal stability compared to the free enzyme. Moreover, BSA-Cu@CaPs-OPH could retain more than 75% and 56% of initial activity after reuse 5 and 10 times, respectively. The results demonstrated that this facile strategy was promising for the effective biodegradation of organophosphorus pesticides with the immobilized enzyme.

In the present work, the effect of oxides on the alkylation of benzene with 1-dodecene was comprehensively investigated over MCM-49 n-heptanol, n-heptaldehyde and n-heptanoic acid were selected as the model oxides herein, and obvious decrease of lifetime could be caused by only trace amount of oxides added in the feedstocks. However, the deactivated catalysts were difficult to be regenerated by extraction with hot benzene. Additionally, coke-burning was also proved to be incapable to regenerate the deactivated catalysts mainly for the dealumination during calcination. Further characterizations complementary with DFT calculations were conducted to demonstrate that the deactivation was mainly due to the firm adsorption of oxides on the acid sites.

A coralloid 3D g-C₃N₄ supported VO₂ catalyst was successfully synthesized in-situ by one-pot method, avoiding the agglomeration of VO₂ during the reaction. The morphological and compositional information of the supported catalyst were investigated detailedly. 30% VO₂/3D g-C₃N₄ revealed excellent catalytic activity in aerobic oxidative desulfurization, the oxidative of dibenzothiophene (DBT), 4-methyldibenzothiophene (4-MDBT) and 4,6-dimethyldibenzothiophene (4,6-DMDBT) reached 98.6%, 99% and 99.4%, respectively, under the same mild conditions. The recycling performance and the mechanism on the oxidative of DBT were studied as well.

Synthetic biotechnology has led to the widespread application of genetically modified organisms (GMOs) in biochemistry, bioenergy, and therapy. However, the uncontrolled spread of GMOs may lead to genetic contamination by horizontal gene transfer, resulting in unpredictable biosafety risks. To deal with these challenges, many effective methods have been developed for biocontainment. In this article, we summarize and discuss recent advances in biocontainment strategies from three aspects: DNA replication, transcriptional regulation, and protein translation. We also briefly introduce the efforts in the biocontainment convention, such as the recent publication of the Tianjin Biosecurity Guidelines for the Code of Conduct for Scientists.

The development of polyoxometalates for olefin oxidation is critical to achieving the green chemical process of the C5 fraction further processing. Di-lacunary silicotungstic anions were easily obtained by continuously adjusting the pH instead of the traditional step-by-step method, which exhibited excellent performance in the catalytic oxidation of cyclopentene (CPE) to aldehydes or alcohols. The 93.69% CPE conversion and 97.15% total product selectivity (41.38% for glutaraldehyde (GA) and 55.77% for 1,2-cyclopentanediol (1,2-diol) were achieved by using H₂O₂ as the oxidant and acetonitrile as the solvent. Through complementary characterization, it was found that the optimized di-lacunary silicotungstic polyoxometalate retained a complete Keggin structure, and exhibited better catalytic activity and stability than the mono-lacunary or saturated silicodecatungstate because it exposed more catalytic active centers. Furthermore, in situ FT-IR spectra was utilized to monitor the reaction process, revealing the formation of the active species W(O₂) on the di-lacunary silicotungstic polyoxometalate and the intermediate epoxycyclopentane during the catalytic oxidation of cyclopentene.

Mechanistic understanding of the active intermediates of 2,6-diaminopyridine (DAP) dinitration in the concentrated nitric-sulfuric acid system is of crucial importance for the selectivity control of target product, i.e., 2,6-diamino-3,5-dinitropyridine (DADNP). The active intermediates determining the product selectivity are theoretically studied. The HSO₄^--NO₂⁺ complex is proposed as the dominant active nitrating intermediate for the first time, which shows low energy barrier (i.e., 10.19 kcal·mol^-1,1 kcal = 4.186 kJ) for direct dinitration of DAP to DADNP. The formed water during the reaction results in not only the formation of less active SO₄^2--NO₂⁺ complex, but also the occurance of DAP sulfonation (DAP-SO₃H intermediate) to facilitate the formation of mononitration byproduct. Meanwhile, the accompanied thermal effects cause the generation of undesirable pyridine-NHNO₂ intermediate, which is difficult to be rearranged to yield DADNP, inhibiting the reaction and thus giving low DAP conversion. The insights reported here elucidates the importance of thermal effects elimination and water content control, confirmed experimentally in the batch- and micro-reaction systems.

Nowadays, chemical safety has attracted considerable attention, and chemical gas leakage monitoring and source term estimation (STE) have become hot spots. However, few studies have focused on sensor layouts in scenarios with multiple potential leakage sources and wind conditions, and studies on the risk information (RI) detection and prioritization order of sensors have not been performed. In this work, the monitoring area of a chemical factory is divided into multiple rectangles with a uniform mesh. The RI value of each grid node is calculated on the basis of the occurrence probability and normalized concentrations of each leakage scenario. A high RI value indicates that a sensor at a grid node has a high chance of detecting gas concentrations in different leakage scenarios. This situation is beneficial for leakage monitoring and STE. The methods of similarity redundancy detection and the maximization of sensor RI detection are applied to determine the sequence of sensor locations. This study reveals that the RI detection of the optimal sensor layout with eight sensors exceeds that of the typical layout with 12 sensors. In addition, STE with the optimized placement sequence of the sensor layout is numerically simulated. The statistical results of each scenario with various numbers of sensors reveal that STE is affected by sensor number and scenarios (leakage locations and winds). In most scenarios, appropriate STE results can be retained under the optimal sensor layout even with four sensors. Eight or more sensors are advised to improve the performance of STE in all scenarios. Moreover, the reliability of the STE results in each scenario can be known in advance with a specific number of sensors. Such information thus provides a reference for emergency rescue.

A new category of lithium greases was synthesized by using poly-α-olefin (PAO8) and alkyl-tetralin as base oil, where the alkyl-tetralins were synthesized by the alkylation of tetralin and olefins. The influence of thickener concentration, alkyl-tetralin content and type of blend oils on the rheological and tribological performance of lithium grease was investigated. The microstructures of soap fibers were measured to reveal the structure–property correlations. The concentration of thickener and alkyl-tetralin content obviously affect the lubricating performance of lithium grease, while the molecular structure of alkyl-tetralin has no obvious impact on their properties. It was found that alkyl-tetralin could significantly enhance the thickening ability of PAO8 base oils, and decrease the amount of thickeners by 1.5% (mass). Lithium greases prepared using 20% (mass) alkyl-tetralin as co-base oil exhibited high colloidal stability, excellent rheological behaviors and tribological properties.

NH₃ selective catalytic reduction (SCR) has been widely recognized as a promising technique for reducing nitrogen oxides from diesel vehicle exhausts. High-efficiency SCR catalysts that could perform at low temperatures are essential to denitration. In this work, a series of bimetallic CeCu-SAPO-34 molecular sieves were synthesized by one-step hydrothermal method. The CeCu-SAPO-34 maintained good crystallinity and a regular hexahedron appearance of Cu-SAPO-34 after introducing Ce species, while exhibiting a higher specific surface area and pore volume. The as-prepared CeCu-SAPO-34 with 0.02% (mass) Ce constituent exhibited the best catalytic activity below 300 ℃ and a maximum NO_x conversion of 99% was attained; the NO_x removal rates of more than 68% and 94% were achieved at 150 ℃ and 200 ℃, respectively. And the introduction of cerium species in Cu-SAPO-34 improves the low-temperature hydrothermal stability of the catalyst towards NH₃-SCR reaction. Additionally, the introduced Ce species could enhance the formation of abundant weak Brønsted acid centers and promote the synergistic effect between CuO grains and isolated Cu²⁺ to enhance the redox cycle, which benefit the NH₃-SCR reaction. This work provides a facile synthesis method of high-efficiency SCR denitration catalysts towards diesel vehicles exhaust treatment under low temperature.

Solid–liquid suspension in stirred tank is a common operation in the chemical industry. The power consumption, flow pattern and flow field instability of three systems named as unbaffled stirred tank, traditional baffled stirred tank and punched baffled stirred tank (Pun-BST) were studied by using the computational fluid dynamic analysis. Results showed that perforating holes in the baffles could reduce power consumption of mixing. Meanwhile, the punched baffle system could maintain the solids in suspension as traditional baffle system. The results also showed that the baffles could increase the “effective flow” of stirred tank even though the whole velocity of the vessel is lower than un-baffled vessel. In addition, both the solid–liquid suspension and “effective flow” were related to instability of the flow field. Perfect solid–liquid suspension results always along with obvious instability of the flow field. But, the strengthening effect of punched baffle on flow field instability mainly happened in the near-wall area. It’s because the collision and aggregation among sub-streams induced by holes intensified the unstable fluid flow. On the whole, the Pun-BST system provided much better mixing characteristics and recommended to apply in the industrial process.

In this research study, we have synthesized the bio-capped ZnO/g-C₃N₄ nanocomposites by employing lemon juice (Citrus limon) as a stabilizer and mediator. Fruitfully, lemon juice which contains various acidic functional groups and citric acid has the capability to block the surface of g-C₃N₄ from chemical reactivity and activated the surface of g-C₃N₄ for various reactions. Consequently, the agglomeration behavior and controlled shape of g-C₃N₄ has also been achieved. Our experimental results i.e. XRD, TEM, HRTEM, PL, FS, XPS, and PEC have confirmed that the lemon juice mediated and green g-C₃N₄ (L-CN) have good performances and remarkable visible light photocatalytic activities as compared to the chemically synthesized g-C₃N₄ (CN). Furthermore, the small surface area and low charge separation of g-C₃N₄ is upgraded by coupling with ZnO nanoparticles. It is proved that the coupling of ZnO worked as a facilitator and photoelectron modulator to enhance the charge separation of g-C₃N₄. Compared to pristine lemon-mediated green g-C₃N₄ (L-CN), the most active sample 5ZnO/L-CN showed ~ 5-fold improvement in activities for ciprofloxacin (CIP) and methylene blue (MB) degradation. More specifically, the mineralization process and degradation pathways, and the mineralization process of ciprofloxacin (CIP) and methylene blue (MB) are suggested. Finally, our present novel research work will provide new access to synthesize the eco-friendly and bio-caped green g-C₃N₄ nanomaterials and their employment for pollutants degradation and environmental purification.

Antioxidants addition is believed as a facile and effective way to improve jet fuel thermal oxidation stability. However, amine antioxidants, as one of the most important antioxidants, have not received sufficient attention in the field of jet fuel autoxidation yet. Herein, the inhibition efficiency and mechanism of decane and exo-tetrahydrodicyclopentadiene (THDCPD) oxidation by di-4-tert-butylphenylamine (diarylamine) was experimentally and theoretically investigated. The results show that diarylamine can significantly inhibit decane oxidation but is less efficient for THDCPD oxidation, which is attributed to the higher energy barrier of retro-carbonyl-ene reaction (rate-determining step) in THDCPD than that in decane during diarylamine regeneration. However, the addition of diarylamine will cause undesirable color change after accelerated oxidation and produce slightly more deposits during high-temperature thermal oxidative stress for both decane and THDCPD. The results provide significant implications for the future design of effective antioxidant additives for high-performance jet fuel.

A series of ZnO/SiO₂ adsorbents were prepared by a sol–gel method using tetraethyl orthosilicate, ethylene glycol (EG) and nitrates as precursors. The effect of gel drying temperature on the structure and desulfurization performance of the adsorbents were investigated in detail. It is found that the low drying temperature led to a weak interaction among EG, SiOH/H₂O and the nitrates in the gel system, which caused the oxidation of EG by NO₃^- and formed zinc glyoxylate complex during the gel calcination process, whereas this oxidation process also occurred at a high drying temperature during the gel drying process. The formed zinc glyoxylate complex promoted the generation of monodentate carbonate on the surface of ZnO, which resulted in the inferior desulfurization performance of adsorbents despite they have smaller ZnO nanoparticles. The gel dried at 120 ℃ formed the hydrogen bonds between EG and SiOH/H₂O and a strong interaction between zinc oxo-clusters and NO₃^- was also found in the gel system, which avoided the oxidation of EG by NO₃^- during the preparation process and the ZnO nanoparticles with sizes of 6 nm were formed by a combustion method. The adsorbent affords a highest sulfur capacity of 104.9 mg·g^-1 in this case. In addition, the gel drying temperature has a significant influence on the textural properties of the adsorbents except their surface area.

Although buoyancy and cracking reactions are strongly coupled in the active cooling process, most of the previous studies consider only one of these factors, and their coupling relationship has not been considerably examined. In this work, this coupling relationship was numerically investigated with complete consideration of different cases of heating, and in the view of energy transport and conversion. By comparing with the no-gravity case (NGC), the results indicate that buoyancy has a significant effect on the bottom-heated case (BHC) and side-heated case (SHC), but has little influence on the top-heated case (THC) owing to the different magnitudes of secondary flow. The heat transfer of the BHC and SHC was significantly enhanced by the secondary flow, but their energy conversion was simultaneously impaired. The conversion of the BHC and SHC was approximately half that of the THC and NGC. For all cases, by analyzing the energy transport ways, the cross section can be classified into three regions in the heating direction. Laminar conduction dominates in region I, but gradually fails in region II, where its role is replaced by other energy transport ways. In region III, convection dominates the energy transport for BHC and SHC, whereas turbulence dominates for THC and NGC.

Due to the scale effect, the uniform distribution of reagents in continuous flow reactor becomes bad when the channel is enlarged to tens of millimeters. Microfluidic field strategy was proposed to produce high mixing efficiency in large-scale channel. A 3D spiral baffle structure (3SBS) was designed and optimized to form microfluidic field disturbed by continuous secondary flow in millimeter scale Y-shaped tube mixer (YSTM). Enhancement effect of the 3SBS in liquid–liquid homogeneous chemical processes was verified and evaluated through the combination of simulation and experiment. Compared with 1 mm YSTM, 10 mm YSTM with 3SBS increased the treatment capacity by 100 times, shortened the basic complete mixing time by 0.85 times, which proves the potential of microfluidic field strategy in enhancement and scale-up of liquid–liquid homogeneous chemical process.

It is known that injection of carbon dioxide into the petroleum reservoir (CO₂ flooding) is one of the effective methods for enhanced oil recovery. CO₂ flooding may be complicated by formation of CO₂ hydrate plugs. It makes topical investigation of CO₂ hydrate formation in the system gaseous CO₂–oil–water. In this work, the growth rates of carbon dioxide hydrate films at the water–oil as well as the water–gas interface are studied in the pressure range of 2.30–3.04 MPa and at temperatures between –5.4 and 5.0 ℃. It is found that the growth rate for the water–oil interface is 3.5 times lower than that for the water–gas interface with carbon dioxide. It is hypothesised that the observed decrease in the growth rate is related to the mechanical resistance of the oil components adsorbed on the interface to the growth of the hydrate film. The growth rate of the film has been shown to depend on the experimental procedure, most likely due to the different initial concentrations of carbon dioxide in the aqueous solutions.

High-quality standard oil synthetic zeolite-13 (SSZ-13) membranes with thickness only ~ 1.0 μm were prepared on tubular supports by the new seeded-gel approach. Seeded-gel approach is simpler than the normal secondary-growth one since adding seeds in the gel is simpler than seeding on the support surface. The synthesis time was greatly reduced from 3.0 to 1.0 d after synthesis modification of gel aging and seed sizes. Low temperature ozone calcination was used for the removal of the organic structural directing agent. The best SSZ-13 membrane displayed CO₂ permeances of 1.3×10^–6 and 1.5×10^–6 mol·m^-2·s^-1·Pa^-1 and CO₂/CH₄ and CO₂/N₂ selectivities of 125 and 27 for equimolar CO₂/CH₄ and CO₂/N₂ mixtures at 0.2 MPa pressure drop and 298 K, respectively. Separation performance of the membrane in the two binary mixtures is higher than that of most zeolite membranes. Three SSZ-13 membranes were reproducibly prepared on tubular supports by seeded-gel approach and the standard deviation ratios of CO₂ permeance and CO₂/CH₄ selectivity are 12.5% and 7%, respectively. It suggests that this new synthesis approach is creditable. The effects of temperature and pressure on separation performance of the thin SSZ-13 membranes were studied in the two binary mixtures. The tubular SSZ-13 membranes displayed great potentials for CO₂ capture from natural gas, biogas and flue gas.

In this work, flow pattern and mass transfer of liquid–liquid two-phase flow in a wire-embedded concentric microchannel are studied using toluene–water system. Droplet flow, slug flow, oval flow and annular flow are observed in the wire-embedded concentric microchannel. The effects of embedded wires and physical properties on flow patterns are investigated. The embedded wire insert is conducive to the formation of annular flow. The flow pattern distribution regions are distinguished by the Ca_aq (capillary number)–We_org (Weber number) flow pattern map. When We_org<0.001, slug flow is the main flow pattern, and when We_org>0.1, annular flow is the main flow pattern. Oval flow and droplet flow are between We_org = 0.001–0.1, and oval flow is transformed into droplet flow with the increase of Ca_aq. The effect of flow rate, phase ratio, initial acetic acid concentration, insert shape and flow patterns on mass transfers are studied. Mass transfer process is enhanced under annular flow conditions, the volumetric mass transfer coefficient is up to 0.36 s^-1 because of the high interfacial area and interface renewal rate of annular flow.

Although having been increasingly studied, there is still controversy as to when the addition of nanoparticles could improve the drag reduction performance of polymer drag reducer and particularly what is the underlying mechanism from the fluid dynamics viewpoint. The drag reduction effects of adding SiO₂ nanoparticles to various polymer polyacrylamide (PAM) solutions were examined in this work. The optimal combination of SiO₂ nanoparticles with cationic polyacrylamide was confirmed. Interestingly, the addition of SiO₂ nanoparticles to cationic polyacrylamide solution was shown to be quite efficient for reducing drag, but only at higher flow rates with Reynolds numbers more than 6000, below which the nanoparticle addition is even negative. The addition of SiO₂ nanoparticles to the PAM solution is supposed to play a dual role. The first is an increase in flow resistance caused by the Brownian motion of nanoparticles, while the second is a decrease in flow resistance caused by acting as nodes to protect the polymer chain from shear-induced breaking under high shear action. At optimal nanoparticle concentration and under higher Reynolds numbers, the later effect is dominant, which could improve the drag reduction performance of polymer drag reducers. Our work should serve as a guide for the application of natural gas fracturing, where the flow rate is frequently very high.

During the last decade, metal–organic frameworks (MOFs) have been applied in various fields due to their unique chemical and functional advantages. One of the widespread research hotspots is MOF-based membranes for separations, specifically continuous defect-free MOF membranes, which are usually grown on porous substrates. The substrate not only serves as the MOF layer support but also has a great influence on the membrane fabrication process and the final separation performance of the resultant membrane. In this review, we mainly introduce the progress focused on the substrates for MOF membranes fabrication. The substrate modifications and seeding methods aimed at synthesizing high-quality MOF membranes are also summarized systematically.

In order to further improve the catalytic performance of zeolite catalyst for methanol to aromatics (MTA) technology, the double-tier SAPO-34/ZSM-5/quartz composite zeolite films were successfully synthesized via hydrothermal crystallization. The Si/Al ratio of SAPO-34 film was used as the only variable to study this material. The composite zeolite material with 0.6Si/Al ratio of SAPO-34 has the largest mesoporous specific surface area and the most suitable acid distribution. The catalytic performance for the MTA process showed that 0.6-SAPO-34/ZSM-5/quartz film has as high as 50.3% benzene-toluene-xylene selectivity and 670 min lifetime. The MTA reaction is carried out through the path we designed to effectively avoid the hydrocarbon pool circulation of ZSM-5 zeolite, so as to improve the aromatics selectivity and inhibit the occurrence of deep side reactions to a great extent. The coke deposition behavior was monitored by thermogravimetric analysis and gas chromatograph/mass spectrometer, it is found that with the increase of Si/Al ratio, the active intermediates changed from low-substituted methylbenzene to high-substituted methylbenzene, which led to the rapid deactivation of the catalyst. This work provides a possibility to employ the synergy effect of composite zeolite film synthesizing anti-carbon deposition catalyst in MTA reaction.