Polymer reaction engineering studies the design, operation, and optimization of reactors for industrial scale polymerization, based on the theory of polymerization kinetics and transfer processes (e.g., flow, heat and mass transfer). Although the foundation and development of this discipline are less than 80 years, the global production of polymers has exceeded 400 million tons per annum. It demonstrates that polymer reaction engineering is of vital importance to the polymer industry. Along with the maturity of production processes and market saturation for bulk polymers, emerging industries such as information technology, modern transportation, biomedicine, and new energy have continued to develop. As a result, the research objective for polymer reaction engineering has gradually shifted from maximizing the efficiency of the polymerization process to the precise regulation of high-end product-oriented macromolecules and their aggregation structures, i.e., from polymer process engineering to polymer product engineering. In this review, the frontiers of polymer reaction engineering are introduced, including the precise regulation of polymer chain structure, the control of primary aggregation structure, and the rational design of polymer products. We narrow down the topic to the polymerization reaction engineering of vinyl monomers. Moreover, the future prospects are provided for the field of polymer reaction engineering.

Sulfate radical-advanced oxidation processes (SR-AOPs) are promising technologies for organic pollutants elimination. Heterogeneous metal-based catalysis has been widely studied and applied to activate peroxymonosulfate (PMS) for producing sulfate radicals. Developing highly efficient catalysts is crucial for future extensive use. Importantly, the catalytic activity is mainly determined by mass and electron transfer. This paper aims to overview the recent enhancement strategies for developing heterogeneous metal-based catalysts as effective PMS activators. The main strategies, including surface engineering, structural engineering, electronic modulation, external energy assistance, and membrane filtration enhancement, are summarized. The potential mechanisms for improving catalytic activity are also introduced. Finally, the challenges and future research prospects of heterogenous metal-based catalysis in SR-AOPs are proposed. This work is hoped to guide the rational design of highly efficient heterogenous catalysts in SR-AOPs.

In the past decade, perovskite solar cells have become a promising candidate in the photovoltaic industry owing to their high power conversion efficiency that surpasses 25%. However, there are certain limitations that have hindered the development and full-scale practical application of these cells, including the high cost and degradation of perovskite caused by the dopants. Hence, there is an urgent need to develop dopant-free hole transport materials (HTMs). In recent years, HTMs based on triphenylamine (TPA-HTMs) are receiving growing interest owing to their high hole mobility, excellent film formation, and suitable energy levels. The literature here covers work relevant to TPA-HTMs in the last five years. They have been classified according to different core types. The correlations between performance and structure are summarized, and the future development trend of TPA-HTMs is highlighted.

Polyoxymethylene dimethyl ethers are recognized as the prospective diesel additive to decrease the pollutant emission from the light-duty vehicles, which can be polymerize form the monomer of dimethoxymethane (DMM). The industrial synthesis of DMM is mainly involved two-step process: methanol is oxidized to form the formaldehyde in fixed bed reactor and then reacted with the generated formaldehyde through acetalization in continuous stirred-tank reactor. Due to huge energy consumption, this typical synthesis route of DMM needs to be upgraded and more green routes should be determined. In this review, four state-of-the-art one-step direct synthetic routes, including two upgrading routes (methanol direct oxidation and direct dehydrogenation) and two green routes (methanol diethyl ether direct oxidation and carbon oxides direct hydrogenation), have been summarized and compared. Combination with the reaction mechanism and catalytic performance on the different catalysts, the challenges and opportunities for every synthetic route are proposed. The relationships between catalyst structure and property in different synthesis strategy are also investigated and then the suggestions of the design of catalyst are given about future research directions that efforts should be made in. Hopefully, this review can bridge the gap between newly developed catalysts and synthesis technology to realize their commercial applications in the near future.

The flow ideality of bubbly microflow remains unclear even though it is vital for the design of microreactors, especially the ideality of bubble swarm microflow for large-scale gas-liquid microreaction processes. This work is the first time to report the ideality analysis of the microbubble swarm in a relatively large microchannel. The bubble swarm microflow has undergone two conditions: quasi-homogeneous plug flow and liquid phase/gas-liquid quasi-homogeneous phase two-phase laminar flow. Both the deviations of void fraction and bubble velocity from the ideal plug flow can divide into two parts, and the two transition points simultaneously happen at the velocity ratio of 1.25. There exists a critical capillary number to maintain the quasi-homogeneous plug flow, which could be regarded as the general laws for the design of gas-liquid microreactors. Finally, a novel model is developed to predict the bubble velocity. This work could be very helpful for the large-scale gas-liquid microreactors design.

The deformation of moving slug bubbles and its influence on the bubble breakup dynamics in microchannel were studied. Three bubble morphologies were found in the experiment: slug, dumbbell and grenade shapes. The viscosity effect of continuous phase aggravates the velocity difference between the fluid near the wall and the bubble, resulting in that the continuous phase near the bubble head flows towards and squeezes the bubble tail, which causes the deformation of bubbles. Moreover, the experimental results show that the deformation of bubbles could significantly prolong the bubble breakup period at the downstream Y-junction. There exists the critical capillary number Ca_Cr for the asymmetric breakup of grenade bubbles, Ca_Cr increases with the rise of flow rate and viscosity of the continuous phase.

The energy-minimization multiscale (EMMS) model, originally proposed for gas-solid fluidization, features a stability condition to close the simplified conservation equations. It was put forward to physically reflect the compromise of two dominant mechanisms, i.e., the particle-dominated with minimal potential energy of particles, and the gas-dominated with the least resistance for gas to penetrate through the particle bed. The stability condition was then formulated as the minimization of the ratio of these two physical quantities. Analogously, the EMMS approach was later extended to the gas-liquid flow in bubble columns, termed dual-bubble-size model. It considers the compromise of two dominant mechanisms, i.e., the liquid-dominated regime with small bubbles, and the gas-dominated regime with large bubbles. The stability condition was then formulated as the minimization of the sum of these two physical quantities. Obviously, the two stability conditions were expressed in different manner, though gas-solid and gas-liquid systems bear some analogy. In addition, both the conditions transform the original multi-objective variational problem into a single-objective problem. The mathematical formulation of stability condition remains therefore an open question. This study utilizes noncooperative game theory and noninferior solutions to directly solve the multi-objective variational problem, aiming to explore the different pathways of compromise of dominant mechanisms. The results show that only keeping the single dominant mechanism cannot capture the jump change of gas holdup, which is associated with flow regime transition. Hybrid of dominant mechanisms, noninferior solutions and noncooperative game theory can predict the flow regime transition. However, the game between the two mechanisms makes the two-bubble structure degenerate and reduce to the single-bubble structure. The game of the three mechanisms restores the two-bubble structure. The exploration on the formulation of stability conditions may help to understand the roles and interactions of different dominant mechanisms in the origin of complexity in multiphase flow systems.

Gas-liquid-liquid three-phase slug flow was generated in both hydrophilic and hydrophobic microreactors with double T-junctions. The bubble-droplet relative movement and the local mass transfer within the continuous slug and the dispersed droplet were investigated. It was found that bubbles moved faster than droplets under low capillary number (Ca), while droplets moved faster upon the increase of Ca due to the increased inertia. For the first time, we observed that the increased viscosity of droplets fastened the droplet movement. The mass transfer in the continuous slug was dominated by convection, leading to nearly constant global mass transfer coefficient (k_La); while that in the dispersed droplet was dominated by diffusion, resulting in k_L decreasing along the channel. Such features are analogical to the corresponding gas-liquid or liquid-liquid two-phase slug flow, but the formation of bubble-droplet clusters caused by relative movement lowered the absolute mass transfer coefficient. These results provide insights for the precise manipulation of gas-liquid-liquid slug flow in microreactors towards process optimization.

To reduce the power consumption and improve the mixing performance in stirred tanks, two improved disc turbines namely swept-back parabolic disc turbine (SPDT) and staggered fan-shaped parabolic disc turbine (SFPDT) are developed. After validation of computational fluid dynamics (CFD) model with experimental results, CFD simulations are carried out to study the flow pattern, mean velocity, power consumption, pumping capacity and mixing efficiency of the improved and traditional impellers in a dished-bottom tank under turbulent flow conditions. The results indicate that compared with the commonly used parabolic disc turbine (PDT), the power number of proposed SPDT and SFPDT impellers is reduced by 43% and 12%, and the pumping efficiency is increased by 68% and 13%, respectively. Furthermore, under the same power consumption (0-700 W·m^-3), the mixing performance of both SPDT and SFPDT is also superior to that of Rushton turbine and PDT.

Swirling addition to the stream is beneficial for the fluid mixing. This work aims to study the mixing process intensification in a conventional T-jets mixer by the swirling addition. After experimental verification by the planar laser-induced fluorescence technique, large eddy simulation with the dynamic kinetic energy sub-grid stress model is used to predict how the swirling strength (in terms of swirling number, S_w) and swirling directions affect the mixing performance, e.g. the tracer concentration distribution, mixing time, and turbulent characteristics in the T-jets mixers. Predictions show that the swirling strength is the key factor affecting the mixing efficiency of the process. The overall mixing time, τ₉₀, can be significantly reduced by increasing S_w. Vortex analysis shows that more turbulent eddies appear in the collision zone and the turbulent kinetic energy dissipation rate increases obviously with the swirling addition. When S_w is kept constant, the mixing process can be accelerated and intensified by adding swirling to only one stream, to both streams with the opposite swirling directions, or to both streams with the same swirling directions. Amplification of the mixing process by enlarging the mixer size or increasing the flow rates is also optimized. Thus, this work provides a new strategy to improve the mixing performance of the traditional T-jets mixers by the swirling addition.

Mesoscale drag model is of crucial significance for the reliability and accuracy in coarse-grid Eulerian-Eulerian two-fluid model (TFM) simulations of gas-solid flow hydrodynamics in fluidized bed reactors. Although numerous mesoscale drag models have been reported in the literature, a systematic comparison of their prediction capability from the perspective of heterogeneity analysis is still lacking. In this study, in order to investigate the effect of several typical drag models on the hydrodynamic behaviors, the nonuniformity analysis and the sensitivity to material properties, extensive coarse-grid TFM simulations of a bubbling pilot-scale fluidized bed reactor are carried out. The results demonstrate that the mesoscale drag models outperform the empirical drag model in terms of nonuniformity due to the consideration of the influence of the mesoscale structures on the drag force in the bubbling region. Furthermore, the results reveal that our previously developed three-marker gradient-based drag model considering the solid concentration gradient exhibits satisfactory performance in predicting the bubbling flow hydrodynamics. Besides, the material-property-dependent drag model considering the explicit effect of material properties on drag corrections is most sensitive to the particle diameter. This work provides guideline for possible future improvements of mesoscale models to simulate gas-solid flow more accurately and universally.

CO₂ absorption into absorbents is a widely used method to reduce carbon emissions, in which the concentration gradient near the gas-liquid interface may induce Rayleigh convection (RC). Once RC occurs, the mass transfer rate will be significantly enhanced. Therefore, it is necessary to explore the mass transfer enhancement mechanism further and develop a penetration/surface divergence hybrid mass transfer model. In this study, we conduct research on the process of CO₂ absorption into ethanol with RC. Firstly, we use a multi-relaxation time lattice Boltzmann method to simulate the absorption process and obtain the flow and concentration fields. And we also verify the reliability of the numerical simulation results by comparing with the experimental results. Then, we analyze the characteristics of non-uniform flow and concentration fields in RC. Moreover, we divide the near-interface region into diffusion-dominated and convection-dominated mass transfer zones by checking whether the horizontal average velocity is greater than 1.0×10^-4 m·s^-1. Furthermore, based on the differences in mass transfer mechanisms of the aforementioned two zones, we propose a penetration/surface divergence hybrid model to predict the instantaneous mass transfer coefficient. The prediction results demonstrate that the hybrid model can precisely predict the instantaneous mass transfer coefficient of the entire CO₂ absorption process. Our proposed hybrid model provides a promising way to deal with the complex mass transfer problems with non-uniform flow and concentration fields.

Since the minimum-boiling azeotropes of C2-C8 alcohols with water and high-water content (up to 95% (mass)) in the Fischer-Tropsch aqueous by-products, the separation is energy-intensive and challenging. The energy-saving strategy for the complete separation of the Fischer-Tropsch aqueous by-products has received massive attention in recent decades. In this study, a stripper-sidestream decanter process is proposed by exploiting homogeneous azeotropes (C2-C3 alcohols-water) and heterogeneous azeotropes (C4-C8 alcohols-water). The introduction of the stripping column for pre-dehydration avoids the re-vaporization of the mixture, and energy carried by the overhead vapor is conserved instead of being removed in a condenser. The precise fraction cutting of C1-C3 alcohol-water mixture, C4-C8 alcohols, and water is realized by the sidestream distillation column. The C4-C8 alcohols rich mixture withdrawn from the sidestream flows into the decanter to break the distillation boundary, where the organic phase returns to the sidestream distillation column to obtain the dehydrated C4-C8 alcohols, and the aqueous phase enters the stripping column. Steady-state optimization based on total annual cost (TAC) minimization shows that the stripper-sidestream decanter process reduces TAC by 17.00% and saves energy by 21.27% compared with the conventional three-column distillation process. Further, a control structure of the process is established, and dynamic simulations show that the control structure combining a differential controller with a low-selector exhibits robust control. This study provides a novel design scheme and deepens the insights into the efficient separation of aqueous by-products of the Fischer-Tropsch synthesis.

The precise control of active pharmaceutical ingredient (API) crystal nucleation and polymorphism is a key consideration in pharmaceutical manufacturing. In this study, tunable nanoparticles were developed to regulate the nucleation process of coumarin. Magnetic silica nanoparticles with four different functional groups (—NH₂, —COOH, —SH, —NCO) were prepared and coated on the substrate for inducing the crystallization of coumarin. Confined melt crystallization and microspacing sublimation crystallization methods were used to investigate the regulation mechanism. The results indicated that three metastable forms of coumarin can be obtained as pure components based on the combined influence of crystallization methods and functionalized nanoparticles. Form II could be selectively obtained by microspacing sublimation crystallization on Fe₃O₄@SiO₂—SH substrates, and Form IV could be obtained by confined melt crystallization on Fe₃O₄@SiO₂—NCO substrates. Form III could be obtained by further heating Form IV crystals to 52 ℃ on Fe₃O₄@SiO₂—NCO substrates. Moreover, the polarized light microscopy results also indicated that the introduction of nanoparticles could also increase the stability of the metastable crystalline forms of coumarin. Finally, the diffusion and surface dynamics during nanoparticle induced crystallization were comparatively investigated and the corresponding polymorphic selectivity mechanism was proposed.

Membrane technology features inspiring excellence from numerous separation technologies for CO₂ capture from post-combustion gas. Polyvinylamine (PVAm)-based facilitated transport membranes show significantly high separation performance, which has been proven promising for industrial scale-up. However, commercialized PVAm with low molecular weight and excessive crystallinity is not available to prepare high-performance membranes. Herein, the synthesis process of PVAm was optimized by regulating polymerization and acidic hydrolytic conditions. The membranes based on PVAm with a molecular weight of 154 kDa and crystallinity of 11.37% display high CO₂ permeance of 726 GPU and CO₂/N₂ selectivity of 55 at a feed gas pressure of 0.50 MPa. Furthermore, we established a PVAm synthesis reactor with an annual PVAm solution (1%(mass)) capacity of over 7000 kg and realized the scaled-up manufacture of both PVAm and composite membranes.

CO₂, one of the main components of greenhouse gases, increased rapidly because of the growing use of fossil fuels. And CaO sorbents possess the capability to be used in capture of CO₂ at high temperature. In the work, Ca—Al complex oxides derived from citrate and stearate intercalated layered double hydroxides were fabricated and their CO₂ adsorption capacity was compared with that from CO₃^2- intercalated layered double hydroxides. The results presented that the sorbents (Ca/Al = 5) with Ca—Al—citrate layered double hydroxides as precursors performed best and displayed remarkable CO₂ capture capacity of 52.0% (mass) at the carbonization temperature of 600 ℃ without distinct recession during cycling adsorption/desorption tests. The excellent CO₂ adsorption capacity of the sorbent was ascribed to its smaller crystallite size of calcinated particles, optimized pore size distribution as well as homogeneous distributed Ca and Al in the sorbent.

Polyamide (PA) thin-film composite (TFC) nanofiltration (NF) membrane has extremely broad application prospects in separation of monovalent/divalent inorganic salts mixed solution. However, membrane fouling is the main obstacle to the application of PA, TFC and NF membrane. Streptomycin (SM) is a hydrophilic antibiotic containing a large number of hydroxyl and amino groups. In this work, the NF membrane was prepared via interfacial polymerization (IP) between trimesoyl chloride (TMC) in the organicphaseand SM/piperazine (PIP) mixture in theaqueousphase. The NF membrane structure and performance were characterized in detail. The results showed that SM successfully participated in the IP. The negative charge and hydrophilicity of membrane surface were improved. The prepared membrane exhibited good anti-adhesion and anti-bacterial performance. Additionally, when the SM concentration was 2%, the prepared membrane exhibited the optimal permselectivity. The water permeance was 89.4 L·m^-2·h^-1·MPa^-1. The rejection of NaCl and Na₂SO₄ were 17.17% and 97.84%, respectively. The NaCl/Na₂SO₄ separation factor of the SM2-PIP/TMC membrane in 1000 mg·L^-1 NaCl and 1000 mg·L^-1 Na₂SO₄ mixed solution was 40, which was 3.3 times that of PIP/TMC membrane. It indicated that SM2-PIP/TMC demonstrated excellent monovalent/divalent salts separation performance. This work provided an easy and effective approach to preparing anti-fouling NF membrane while possessing superior monovalent/divalent salts separation performance.

The resource utilization of hydrogen sulfide (H₂S) is of great significance in natural gas chemical industry. Described herein have developed a novel method mediated in tertiary amine-functionalized ionic liquids (ILs) to convert H₂S into mercaptan alcohols with enols. The effect of ILs, substrate scope, and regeneration experiments have been investigated. It is found that the conversion of 3-methyl-2-buten-1-ol by H₂S can reach 52% with a 50% (mol) catalyst loading of bis(2-dimethylaminoethyl) ether methoxyacetate within 12 h at 90 ℃. The reaction mechanism was speculated based on theoretical calculation. Besides, a plausible reaction-separation-integrated strategy was further proposed. This work reveals an effective insight into the capture and catalytic conversion of H₂S to high valuable mercaptan alcohol, which makes the utilization method of H₂S resource universal and has the potentiality for industrial application.

In this work, a strategy of “etching-modification filling-graft copolymerization” was proposed to load the acidic ionic polyionic liquid on the smooth ceramic surface. In this way, commercial ceramic Raschig rings were successfully transformed into the supported catalytic packing for the reactive distillation, and were further evaluated with esterification reaction of ethyl acetate by means of the fully mixed reactor, the ultrasonic destruction, the cyclic catalysis reaction and the lab-scale distillation column experiment. This catalyst coating has good adhesion with the substrate. It can withstand 24 h of ultrasound damage and shows good stability in three cycle catalytic experiments. This kind of coated catalyst has better catalytic activity than the commercial Amberlyst 15 dry. In the lab-scale reaction distillation, the supported catalyst Raschig ring can achieve a higher conversion in comparison with the tea bag catalytic packing of Amberlyst 15 dry under some conditions.

Catalytic oxidation of Hg⁰ to HgO is an efficient way to remove Hg⁰ from coal-fired flue gas. The catalyst with ordered pore structure can lower mass transfer resistance resulting in higher Hg⁰ oxidation efficiency. Therefore, in the present work, wood vessels were used as sacrificial template to obtain Co₃O₄ with ordered pore structure. SEM and BET results show that, when the mass concentrations of Co(NO₃)₂·6H₂O was 20%, the obtained catalyst (Co₃O₄ [20%Co(NO₃)₂]) possesses better pore structure and higher surface area. It will expose more available surface active sites and lower the mass transfer resistance. Furthermore, XPS results prove that Co₃O₄ [20%Co(NO₃)₂] has the highest ratio of chemisorbed oxygen which plays an important role in Hg⁰ oxidation process. These results lead to a better Hg⁰ oxidation efficiency of Co₃O₄ [20%Co(NO₃)₂], which is about 90% in the temperature range of 200 to 350 ℃. Furthermore, Co₃O₄ [20%Co(NO₃)₂] has a stable catalytic activity, and its Hg⁰ oxidation efficiency maintains above 90% at 250 ℃ even after 90 h test. A probable reaction mechanism is deduced by the XPS results of the fresh, used and regenerated catalyst of Co₃O₄ [20%Co(NO₃)₂]. Chemisorbed oxygen can react with Hg⁰ forming HgO with the reduction of Co³⁺ to Co²⁺. And lattice oxygen and gaseous oxygen can supplement the consumption of chemisorbed oxygen to oxidize Co²⁺ to Co³⁺.

A feasible synthesis route is developed for achieving the direct carboxylation of thiophene and CO₂ in a relatively mild solvent-free carboxylate-assisted carbonate (semi) molten state. The effects of reaction factors on the carboxylate yield are investigated in the preliminary screening experiments, and the phase behavior analysis of the reaction medium is detected through the thermal characterization analysis of in-situ high temperature X-ray diffraction measurement (in-situ XRD). The application of response surface methodology (RSM) based on the Box-Behnken design (BBD) is conducted to investigate the effect of the reaction parameters, such as reaction temperature, carbonate proportion, CO₂ pressure and thiophene amount, on the product yield. The regressed second-order polynomial model equation well correlates all the independent variables. The analysis of variance (ANOVA) results reveal that the quadratic effect of reaction temperature is the most effective parameter in this carboxylation reaction owing to it’s the highest contribution to the sum of square (30.18%). The optimum reaction conditions for maximum product yield are the reaction temperature of 287 ℃, carbonate proportion of 32.20%, CO₂ pressure of 1.0MPa and thiophene amount of 9.35 mmol. Operating under these selected experimental conditions, a high product yield (50.98%) can be achieved.

The bimetallic nanoparticles compositing of Ni-rich core and Cu-rich shell (Ni/Cu NPs) were successfully synthesized by a liquid-phase thermal decomposition method. The content of copper and nickel in Ni/Cu NPs was controllable by adjusting the ratio of two metal precursors, copper formate (Cuf) and nickel acetate tetrahydrate (Ni(OAc)₂·4H₂O). Ni/Cu NPs were further anchored on graphene oxide (GO) to prepare a magnetic composite catalyst, called Ni/Cu-GO. The dispersibility of Ni/Cu NPs in solution was enhanced by GO anchoring to prevent the sintering and aggregation during the reaction process, thereby ensuring the catalytic and cycling performance of the catalyst. The catalytic transfer hydrogenation (CTH) reaction of nitroaromatics was investigated when ammonia borane was used as the hydrogen source. Cu dominated the main catalytic role in the reaction, while Ni played a synergistic role of catalysis and providing magnetic properties for separation. The Ni₇/Cu₃-GO catalyst exhibited the best catalytic performance with the conversion and yield of 99% and 96%, respectively, when 2-methyl-5-nitrophenol was used as the substrate. The Ni₇/Cu₃-GO catalyst also exhibited excellent cyclic catalytic performance with the 5-amino-2-methylphenol yield of above 90% after six cycles. In addition, the Ni₇/Cu₃-GO catalyst could be quickly recycled by magnetic separation. Moreover, the Ni₇/Cu₃-GO catalyst showed good catalytic performance for halogen-containing nitroaromatics without dehalogenation.

Carbon dioxide (CO₂) utilization and fixation have become one of the most important research areas nowadays due to the increase of global greenhouse effect. Cyclic carbonate, which is widely used in various fields, can be synthesized by fixation of CO₂ with epoxide in industry. Moreover, the synthesis of cyclic carbonate is a 100% atom economical reaction, which makes it eco-friendly and promising. To enhance the reaction efficiency and safety, a microreaction system was used as the platform for cycloaddition reaction. In this work, tetrabutylammonium bromide (TBAB) was chosen as catalyst, and propylene oxide (PO) as a mode substrate. Interestingly, the addition of water can increase the propylene carbonate (PC) yield and decrease the activation energy considerably, proving water as catalyst promoter for PC synthesis. PC yield and selectivity could reach 91.6% and 99.8%, respectively. The Influence factors and kinetic equation for CO₂ cycloaddition were obtained as well.

The coupling of reaction and diffusion between neighboring active sites in the catalyst pore leads to the spatiotemporal fluctuation in component concentration, which is very important to catalyst performance and hence its optimal design. Molecular dynamics simulation with hard-sphere and pseudo-particle modeling has previously revealed the non-stochastic concentration fluctuation of the reactant/product near isolated active site due to such coupling, using a simple model reaction of A → B in 2D pores. The topic is further developed in this work by studying the concentration fluctuation due to such coupling between neighboring active sites in 3D pores. Two 3D pore models containing an isolated active site and two adjacent active sites were constructed, respectively. For the isolated site, the concentration fluctuation intensifies for larger pores, but the product yield decreases, and for a given pore size, the product yield reaches a peak at a certain reactant concentration. For two neighboring sites, their distance (d) is found to have little effect on the reaction, but significant to the diffusion. For the same reaction competing at both sites, larger d leads to more efficient diffusion and better overall performance. However, for sequential reactions at the two sites, higher overall performance presents at a smaller d. The results should be helpful to the catalyst design and reaction control in the relevant processes.

A feasible synthesis route is devised for realizing direct carboxylation of thiophene and CO₂ in a relatively mild solvent-free carboxylate-assisted carbonate (semi) molten medium. The effects of reaction factors on product yield are investigated, and the phase behavior analysis of the reaction medium is detected through the thermal characterization techniques. Product yield varies with the alternative carboxylate co-salts, which is attributed to the difference in deprotonation capacity caused by the base effect within the system. Besides, the detailed mechanism of this carbonate-promoted carboxylation reaction is studied, including two consecutive steps of the formation of carbanion through breaking the C—H bond(s) via the carbonate and the nucleophile attacking the weak electrophile CO₂ to form C—C bond(s). The activation energy barrier in C—H activation step is higher than the following CO₂ insertion step whether for the formation of the mono- and/or di-carboxylate, which is in good agreement with that of kinetic isotope effect (KIE) experiments, indicating that the C—H deprotonation is slow and the forming presumed carbanion reacts rapidly with CO₂. Both the activation energy barriers in deprotonation steps are the minimal for the cesium cluster system since there have the weak the cesium Cs-heteroatom S (thiophene) and Cs-the broken proton interactions compared to the K₂CO₃ system, which is likely to enhance the acidity of C—H bond, lowering the C—H activation barrier. Besides, these mechanistic insights are further assessed by investigating base and C—H substrate effects via replacing Cs₂CO₃ with K₂CO₃ and furoate (1a) with thiophene monocarboxylate (1b) or benzoate (1c).

Recently, cyclic (alkyl)(amino)carbenes (CAACs) have been widely used as ligands to enhance the catalytic reactivity of center metal, but the problem of recycling this expensive ligand remains to be solved. In this work, the heterogeneous SBA-15-CAAC-Ir catalyst was prepared by a covalent attachment method, and using SBA-15 as the carrier. It shows high reactivity for the hydrogenation of CO₂ to formate. After immobilization, the ordered mesoporous structure and the overall rod-like morphology of the original SBA-15 have been preserved very well. Using SBA-15-CAAC-Ir as catalyst, up to 21050 TON can be obtained at 60 ℃. In addition, the catalyst can be separated easily by centrifugation, and the catalytic activity of SBA-15-CAAC-Ir can still remain very high after multiple cycles.

Hydrogenations and air oxidations usually have low apparent reaction rate, generally controlled by mass transfer rate, and widely exist in the modern chemical manufacturing process. The key to increase the mass transfer rate is the reduction of the liquid film resistance 1/k_La. In this work, the original concept of microinterface intensification for mass transfer and then for these reactions has been proposed. We derived the regulation model and set up the mathematical calculation method of micron-scale gas-liquid interface structure on mass transfer and reaction, designed the mechanical energy exchange device that can produce gas-liquid microinterface system on a large scale, and established the OMIS system which is able on line to measure the diameter and distribution of millions of microbubbles, interface area a and mass transfer film thickness δ_M, as well as developed a series of microinterface intensified reactor systems (MIRs) for the applications of hydrogenation and air oxidation processes. It is believed that this research will provide an up-to-date development for the intensification of hydrogenation and air oxidation reactions.

A simple strategy of Cu modification was proposed to broaden the operation temperature window for NbCe catalyst. The best catalyst Cu_0.010/Nb₁Ce₃ presented over 90% NO conversion in a wide temperature range of 200-400 ℃ and exhibited an excellent H₂O or/and SO₂ resistance at 275 ℃. To understand the promotional mechanism of Cu modification, the correlation among the “activity-structure-property” were tried to establish systematically. Cu species highly dispersed on NbCe catalyst to serve as the active component. The strong interaction among Cu, Nb and Ce promoted the emergence of NbO₄ and induced more Brønsted acid sites. And Cu modification obviously enhanced the redox behavior of the NbCe catalyst. Besides, EPR probed the Cu species exited in the form of monomeric and dimeric Cu²⁺, the isolated Cu²⁺ acted as catalytic active sites to promote the reaction: Cu²⁺-NO₃^-+NO(g) → Cu²⁺-NO₂^-+NO₂(g). Then the generated NO₂ would accelerate the fast-SCR reaction process and thus facilitated the low-temperature deNO efficiency. Moreover, surface nitrates became unstable and easy to decompose after Cu modification, thus providing additional adsorption and activation sites for NH₃, and ensuring the improvement of catalytic activity at high temperature. Since the NH₃-SCR reaction followed by E-R reaction pathway efficaciously over Cu_0.010/Nb₁Ce₃ catalyst, the excellent H₂O and SO₂ resistance was as expected.

The equilibrium and kinetic of hydrate in sediments can be affected by the presence of external components like bentonite with a relatively large surface area. To investigate the hydrate formation and decomposition behaviors in bentonite clay, the experiments of methane hydrate formation and decomposition using the multi-step decomposition method in bentonite with different water contents of 20%, 40% and 60% (mass) were carried out. The contents of bound, capillary and gravity water in bentonite clay and their roles during hydrate formation and decomposition were analyzed. In bentonite with water content of 20% (mass), the hydrate formation rate keeps fast during the whole formation process, and the final gas consumption under different initial formation pressures is similar. In bentonite with the water contents of 40% and 60% (mass), the hydrate formation rate declines significantly at the later stage of the hydrate formation. The final gas consumption of bentonite with the water contents of 40% and 60% (mass) is significantly higher than that with the water content of 20% (mass). During the decomposition process, the stable pressure increases with the decrease of the water content. Hydrate mainly forms in free water in bentonite clay. In bentonite clay with the water contents of 20% and 40% (mass), the hydrate forms in capillary water. In bentonite clay with the water content of 60% (mass), the hydrate forms both in capillary water and gravity water. The bound water of dry bentonite clay is about 3.93% (mass) and the content of capillary water ranges from 42.37% to 48.21% (mass) of the dry bentonite clay.

Low dosage kinetic hydrate inhibitors (KHIs) are a kind of alternative chemical additives to high dosage thermodynamic inhibitors for preventing gas hydrate formation in oil & gas production wells and transportation pipelines. In this paper, a new KHI, poly (N-vinyl caprolactam)-co-tert-butyl acrylate (PVCap-co-TBA), was successfully synthesized with N-vinyl caprolactam (NVCap) and tert-butyl acrylate. The kinetic inhibition performances of PVCap-co-TBA on the formations of both structure I methane hydrate and structure II natural gas hydrate were investigated by measuring the onset times of hydrate formation under different conditions and compared with commercial KHIs such as PVP, PVCap and inhibex 501. The results indicated that PVCap-co-TBA outperformed these widely applied inhibitors for both structure I and structure II hydrates. At the same dosage of KHI, the maximum tolerable degree of subcooling under which the onset time of hydrate formation exceeded 24 hours for structure I hydrate was much lower than that for structure II hydrate. The inhibition strength increased with the increasing dosage of PVCap-co-TBA; The maximum tolerable degree of subcooling for the natural gas hydrate is more than 10 K when the dosage was higher than 0.5% (mass) while it achieved 12 K when that dosage rose to 0.75% (mass). Additionally, we found polypropylene glycol could be used as synergist at the dosage of 1.0 % (mass) or so, under which the kinetic inhibition performance of PVCap-co-TBA could be improved significantly. All evaluation results demonstrated that PVCap-co-TBA was a very promising KHI and a competitive alternative to the existing commercial KHIs.

Based on the COSMO-SAC model, 1-ethyl-3-methylimidazolium acetate and 1-ethyl-3-methylimidazolium p-toluenesulfonate were selected from 30 ILs as entrainers to investigate the separation of the isopropyl alcohol + isopropyl acetate azeotrope. Two screening indicators, σ-profile and infinite dilution selectivity (S^∞), were adopted as the basis. The isobaric vapor-liquid equilibrium experiments for isopropyl alcohol + isopropyl acetate binary system and isopropyl alcohol + isopropyl acetate + confirmed ILs ternary systems were performed at the pressure of atmospheric pressure. The experimental measurement demonstrated that the adopt ILs enhanced the relative volatility of the above alcohol-ester azeotrope, leading to the elimination of the azeotropic point with a certain amount ILs. Meanwhile, the thermodynamic correlation for two systems containing ILs was explored with the NRTL model, which also reflects the extensive applicability of that by comparing the deviation between experimental and calculated data. And its binary interaction parameters were regressed, which can provide a basis for its simulation process.

Whereas the π-π stacking interactions at oil/water interfaces can affect interfacial structures hence the interfacial properties, the underlying microscopic mechanism remains largely unknown. We reported an all-atom molecular dynamics (MD) simulation study to demonstrate how the Gemini surfactants with pyrenyl groups affect the interfacial properties, structural conformations, and the motion of molecules in the water/n-octane/surfactant ternary systems. It is found that the pyrenyl groups tend to be vertical to the interface owing to the π-π stacking interaction. Besides, a synergistic effect between the π-π interaction and steric hindrance is found, which jointly affects the coalescence of liquid droplets. Therefore, the existence of aromatic groups and a moderate number of surfactants helps to form microemulsion. This work provides a molecular understanding of Gemini surfactants with aromatic groups in microemulsion preparation and applications.

Cavitation in water generally takes place at much lower negative pressure than predicted from theories. In this work, we try to stress the discrepancy from the influence of the dissolved gas on cavitation nucleation. By combining molecular dynamics simulation and thermodynamic analysis, we evaluated the lowering of surface tension as a function of density of gas molecules in gas clusters formed in aqueous solution. We found that the obtained surface tension of small gas clusters is much more substantially reduced than expected. The surface tension lowering and the non-ideality of gas molecules in the clusters are then taken into account in determining the nucleation of cavitation, and as a consequence, the required negative pressure for cavitation becomes comparable to experimental values. Thus, we give an alternative explanation for the discrepancy of cavitation pressure between experiment and theory, i.e., it is the substantially reduced surface tension for small gas nuclei, which have not been taken into account in theory, along with the ideal gas approxiamtion that induce its deviation from the experimental values.

Gamma-aminobutyric acid (GABA) is a natural non-protein functional amino acid, which has potential for fermentation industrial production by Lactobacillus brevis. This work investigated the batch fermentation process and developed a kinetic model based on substrate restrictive model established by experimental data from L₂₅(5⁶) orthogonal experiments. In this study, the OD₆₀₀ value of fermentation broth was fixed to constant after reaching its maximum because the microorganism death showed no effect on the enzyme activity of glutamate decarboxylase (GAD). As pH is one of the key parameters in fermentation process, a pH-dependent kinetic model based on radial basis function was developed to enhance the practicality of the model. Furthermore, as to decrease the deviations between the simulated curves and the experimental data, the rolling correction strategy with OD₆₀₀ values that was measured in real-time was introduced into this work to modify the model. Finally, the accuracy of the rolling corrected and pH-dependent model was validated by good fitness between the simulated curves and data of the initial batch fermentation (pH 5.2). As a result, this pH-dependent kinetic model revealed that the optimal pH for biomass growth is 5.6-5.7 and for GABA production is about 5, respectively. Therefore, the developed model is practical and convenient for the instruction of GABA fermentation production, and it has instructive significance for the industrial scale.

γ-Aminobutyric acid (GABA), a natural non-protein amino acid, plays an irreplaceable role in regulating the life activities of organisms. Nowadays, the separation and purification of food-grade GABA from fermentation broth is still a great challenge. This research utilized monosodium glutamate as a substrate for the production of high-purity GABA via an integrated process incorporating fermentation, purification, and crystallization. Firstly, 147 g·L^-1 GABA with a yield of 99.8% was achieved through fed-batch fermentation by Lactobacillus brevis CE701. Secondly, three integrated purification methods by ethanol precipitation were compared, and crude GABA with a purity of 89.85% was obtained by the optimized method. Thirdly, GABA crystals with a purity of 98.69% and a yield of 60% were further obtained through a designed crystallization process. Furthermore, the GABA industrial production process model was established by Superproper Designer V10 software, and material balance and economic analysis were carried out. Ethanol used in the process was recovered with a recovery of 98.79% through Aspen simulated extractive distillation. Then the fixed investment (equipment purchase and installation costs) for an annual production of 80 t GABA will be about 833000 USD; the total annual production cost (raw material cost and utility cost) will be about 641000 USD. The annual sale of GABA may be at the range of 2400000-4000000 USD and the payback period will be about 1-2 year. This integrated process provides a potential way for the industrial-scale production of food-grade GABA.

The adsorption of protein molecules to oil/water (O/W) interface is of critical importance for the product design in a wide range of technologies and industries such as biotechnology, food industry and pharmaceutical industry. In this work, with ovalbumin (OVA) as the model protein, the adsorption conformations at the O/W interface and the adsorption stability have been systematically studied via multiple simulation methods, including all-atom molecular dynamic (AAMD) simulations, coarse-grained molecular dynamic (CGMD) simulations and enhanced sampling methods. The computational results of AAMD and CGMD show that the hydrophobic tail of OVA tends to be folded under long time relaxation in aqueous phase, and multiple adsorption conformations can exist at the interface due to heterogeneous interactions raising from oil and water respectively. To further study the adsorption sites of the protein, the adsorption kinetics of OVA at the O/W interface is simulated using metadynamics method combined with CGMD simulations, and the result suggests the existence of multiple adsorption conformations of OVA at interface with the head-on conformation as the most stable one. In all, this work focuses on the adsorption behaviors of OVA at squalene/water interface, and provides a theoretical basis for further functionalization of the proteins in emulsion-based products and engineering.

A mathematical model is developed for the calculation of the nucleation and growth process of silica nanostructured particles prepared by using the drop-by-drop method, and the calculation results of the proposed model is compared with the experimental value obtained from SAXS data. The model provides a non-ideal improvement in the supersaturation calculation and considers the impact of both mass transfer and surface reaction on the particle growth rate. The nucleation and growth rates are coupled depending on the change in monomer concentration over time, based on which the particle size and distribution are calculated. The growth curve of the silica particles from 3 nm to 20 nm and the change in particle number from 0 to over 10²⁰ are calculated, which are consistent with the experimental values, establishing the reliability of the model. The calculations of the growth rate reveal that mass transfer controls the growth of silica particles before 10 min and the surface reaction is the rate-determining step after 10 min. The changes in the model parameters obtained by fitting with the SAXS data under different reaction conditions indicate the sensitivity of the corresponding process to different conditions. Moreover, the relationship between the particle growth rate and monomer concentration change is analyzed using the proposed model.

With excellent biocompatibility and unique physiochemical properties, nanocelluloses including cellulose nanocrystals (CNCs) and cellulose nanofibrils (CNFs) are promising candidates for preparing biomedical hydrogels. CNCs and CNFs are different in morphology and surface charges. Herein, CNCs and two CNFs (CNFs-C, Carboxylated CNFs; CNFs-P, Phosphorylated CNFs) were synthesized and applied to fabricate hydrogels through metal crosslinking. Aluminum crosslinking was found to be the best choice for enhancing the strength. This study systematically compared the morphologies, storage modulus, loss factor, continuous shear ramp, self-healing, swelling, in vitro degradation and injectable properties of the fabricated hydrogels. Further, a radar chart is summarized as guidelines to direct the rational selection to meet the specific requirements of further biomedical applications. At the same nanocellulose concentration and after Al³⁺ crosslinking, CNCs hydrogels had strong water holding capacity twice as much as that of CNFs hydrogels. While CNFs hydrogels showed higher hardness and stronger resistance to degradation than that of CNCs. These results provide detailed insights into nanocellulose hydrogels, making it possible to use these guidelines to select hydrogels for desired performance.

Intelligent fault recognition techniques are essential to ensure the long-term reliability of manufacturing. Due to the variations in material, equipment and environment, the process variables monitored by sensors contain diverse data characteristics at different time scales or in multiple operating modes. Despite much progress in statistical learning and deep learning for fault recognition, most models are constrained by abundant diagnostic expertise, inefficient multiscale feature extraction and unruly multimode condition. To overcome the above issues, a novel fault diagnosis model called adaptive multiscale convolutional neural network (AMCNN) is developed in this paper. A new multiscale convolutional learning structure is designed to automatically mine multiple-scale features from time-series data, embedding the adaptive attention module to adjust the selection of relevant fault pattern information. The triplet loss optimization is adopted to increase the discrimination capability of the model under the multimode condition. The benchmarks CSTR simulation and Tennessee Eastman process are utilized to verify and illustrate the feasibility and efficiency of the proposed method. Compared with other common models, AMCNN shows its outstanding fault diagnosis performance and great generalization ability.

Simultaneous optimization of refrigeration system (RS) and its heat exchanger network (HEN) leads to a large-scale non-convex mixed-integer non-linear programming (MINLP) problem. Conventionally, researchers usually adopted simplifications to confine problem scale from being too large at the cost of reducing solution space. This study established an optimization framework for the simultaneous optimization of RS and HEN. Firstly, A more comprehensive and compact model was developed to guarantee a relatively complete solution space while reducing model scale as well as its solving difficulty. In this model, a tandem arrangement of connecting sub-coolers and expansion valves was considered in the superstructure; and the pressure/temperature levels were optimized as continuous variables. On this basis, we proposed a “two-step transformation method” to equivalently transform the cross-level structure into a non-cross-level structure, and the de-redundant superstructure was established with ensuring comprehensiveness and rigor. Furthermore, the MINLP model was developed and solved by Particle Swarm Optimization algorithm. Finally, our methodology was validated to get better optimal results with less CPU time in two case studies, an ethylene RS in an existing plant and a reported propylene RS.

The structures of electrode meso-macropore and the solvent polarity are the crucial factors dominating the performance of the electric double layer capacitors (EDLCs), but their impacts are usually tangled and difficult to decouple and quantitate. Here the effects of electrode meso-macropore structure and solvent polarity on the specific capacitance of an EDLC are quantitatively investigated using a steady-state continuum model. The simulation results indicate the specific capacitances are significantly affected by the meso-macropore surface structure. The specific capacitances significantly decrease for both convex surface structures but obviously increase for both concave surface structures, with the increase of curvature radius from 1 to 20 nm. As for solvents, the polar solvent with high saturated dielectric permittivity improves the capacitance performance. Moreover, the electrode meso-macropore structure is of more concern compared with solvent polarity when aiming at enhancing the specific capacitance. These results provide fundamentals for the rational design of porous electrodes and polar electrolytes for EDLCs.

In order to realize efficient gas storage of hydrate, stainless steel fiber (SSF) was added to 0.03% (mass) sodium dodecyl sulfate (SDS) solution for gas storage experiment. SSF can not only improve the problem that hydration heat cannot be removed effectively in the hydration process, but also improve gas storage speed and gas storage by increasing hydrate nucleation sites. Under the experimental conditions (273.2 K, 5-9 MPa), the peaks of temperature rise in SDS + SSF systems were found to become much smaller than those in SDS systems. The maximum gas storage rate and the maximum methane uptake of SSF + SDS system reached 9.89-24.90 cm³·g^-1·min^-1 and 178.65-200.89 cm³·(g H₂O)^-1, respectively. Compared with the surfactant SDS solution without SSF, they increased by 10.47%-33.22% and 9.16%-25.36%, respectively. The effect of SSF length on gas storage performance was studied. Due to the continuous thermal conduction network, longer SSF showed a higher gas storage capacity and methane uptake rate compared with shorter SSF. At the same time, compared with other metal fillers, SSF + SDS not only had excellent gas storage performance, but also the amount of SSF (0.1 g·ml^-1) was only 7.6% of foamed aluminum, and the volume gas storage density was increased by 145.4%. The use of stainless steel fiber made the best use of the thermal conductivity of metal, reduced the amount of metal used, and improved the volume density and mass density of gas storage.