The liquid-solid two-phase fluidized bed has the advantages of high liquid-solid contact efficiency, good mass and heat transfer performance, uniform particle distribution, etc., and has been widely used in many industrial processes. However, due to the complex nonlinear characteristics and turbulent characteristics of the particle fluidization coupled with the mass transfer process in the fluidized bed, it is very difficult to study the characteristics of the mass transfer process. Moreover, it is difficult to reveal the interaction law of multiphase flow and impossible to obtain a comprehensive and detailed distribution of velocity field and concentration field only by relying on experimental observations and theoretical predictions. In recent years, the rapid development of numerical simulation has provided an important way for in-depth exploration of the liquid-solids two-phase flow behavior and its coupling with the mass transfer process in a fluidized bed. In this paper, the simulation methods of fluidized bed liquid-solids two-phase flow and mass transfer process are reviewed, and its future research trends is prospected. With the help of computational mass transfer (CMT) theory, the local concentration distribution can be predicted more accurately, and the mass transfer characteristics in the liquid-solids two-phase fluidized bed can be analyzed in depth, which provides the design and optimization of the liquid-solids two-phase fluidized bed a solid foundation.

With the wide application of polymer materials in human production and life, their fire safety problems have become increasingly prominent, and the development of high-efficiency and environmentally friendly flame-retardant smoke suppressants has become one of the urgent problems to be solved in the current material field. However, the smoke suppressants did not receive enough attention compared to the relatively mature research of flame retardants for a long time. Most of the current researches on smoke suppression of polymers are the investigation of the smoke suppression property of a known flame retardant and thus developing the so-called “bifunctional materials” with both flame retardancy and smoke suppression properties. The insufficient attention on the smoke suppressant materials greatly limits their development. As we have known, the mechanisms of combustion and smoke emission varied on different polymer materials due to the diversity of structure and functional groups within different polymer materials. Therefore, the design of flame retardants and smoke suppressants of different polymers should also be significantly different. Meanwhile, the flame retardancy and smoke suppression performances are hard to be optimized simultaneously with one material. Therefore, we propose to separate the flame retardancy and smoke suppression in two different materials and strengthen the development of single-function smoke suppressants. Optimizing the flame retardants and smoke suppressants based on the chemical nature of the polymers separately and then combining them might be an effective way to improve the flame retardancy and smoke suppression performance of polymer materials in the future.

Ammonia is an important chemical raw material in fertilizer, coating and other fields, and it is the second highest production of commercial chemical. At present, more than 90% of ammonia comes from the Haber-Bosch process. This process requires high temperature and high pressure conditions, high energy consumption, and relies on the use of fossil fuels to produce a large amount of CO₂ emissions. In the new era of advocating energy conservation and environmental protection, the process is facing serious energy consumption and pollution problems. The electrocatalytic nitrogen reduction process for ammonia synthesis is a kind of energy saving process driven by electric energy, and the raw materials are H₂O and N₂. The process is expected to replace the traditional ammonia synthesis process. However, there are some technical difficulties to be broken through in this process. Its ammonia production rate and Faraday efficiency are not high, and there is a big gap between the process and commercial industrial production. In this paper, the technical difficulties of the process are analyzed and summarized. Based on the optimization strategies in this field, the improvement measures for the electrochemical system of synthetic ammonia and the research progress reported in recent years are summarized. Finally, the future development of this field is prospected.

In the investigations of fluidization in recent 100 years, different diameters of fluidized bed are involved. However, most of these studies took the large-scale fluidized bed as the research goal, and did not focus on the characteristics of mini or micro fluidized beds. Therefore, the research and understanding of mini- or micro-fluidized bed is very limited. Fluidized bed, as a special unit operation process and installation to deal with solid particles, its miniaturization has both the advantages of micro channel reactor and macro scale fluidized bed, and is an important research direction of fluidization. The progress of gas-solid micro fluidized bed has been well reviewed. In this review, the research progress of liquid-solid and gas-liquid-solid mini- or micro-fluidized beds is reviewed. The contents of research progress are as follows. When the bed diameter of liquid-solid micro-fluidized bed decreases, the wall effect increases, and measured minimum fluidization liquid velocity is greater than that calculated by Ergun formula; Richardson-Zaki equation describing the law of uniform expansion and fluidization of liquid-solid flow needs to be modified. There are four typical flow patterns in gas-liquid-solid micro fluidized bed: semi-fluidization, slug flow, dispersed bubbling flow and liquid transport flow. Due to the decrease of bed diameter and semi-fluidization, the minimum fluidization liquid velocity cannot be determined according to the pressure drop velocity curve. The reaction performance of gas-liquid-solid micro fluidized bed has been effectively improved. Further research directions are pointed out, so as to provide some reference for the researchers.

Silicon nitride (Si₃N₄) has excellent physical and chemical properties and occupies an important position in key fields such as national defense and electronic information. High quality Si₃N₄ powders are the primary prerequisite for the preparation of high performance Si₃N₄ ceramics. The high-quality powder requisites the conditions of fine particle size with narrow distribution, high α phase, low impurity and so on. The research advances in preparation technology of silicon nitride powder are summarized from the point of the synthesis reaction system, with the emphasis on summarizing the progress of the improvement of powder quality by enhancing heat and mass transfer. In addition, the present situations of industrial manufacture are introduced, and the development trend and direction of the preparation technology of high quality Si₃N₄ powder are also prospected.

The global market for electric vehicles and smartphones has expanded year by year, which has directly promoted the increase of the global lithium-ion battery market. The recovery and reuse of lithium-ion batteries has important economic and social value. In this paper, the main recycling methods of spent cathode materials for lithium-ion batteries are reviewed, including cascade life-cycle reuse method, pyrometallurgical process, hydrometallurgical recovery process and direct recycling method. The process flow and important steps of hydrometallurgical metals reclamation are summarized emphatically, including mechanical treatment, cathode material leaching, recycling of leachate, regeneration and synthesis of valuable metal products. Finally, the future development of comprehensive hydrometallurgical recovery of spent cathode materials for lithium batteries is prospected.

Lithium metal battery has a higher theoretical specific capacity and the lowest oxidation-reduction potential, which is one of the most promising electrochemical energy storage devices. However, some key problems caused by the lithium dendrites on the metal lithium anode seriously hinder its practical application. This article first introduces the mechanisms of multi-morphology lithium dendrites nucleation and growth with the four factors of ion concentration, electric field, stress and temperature. Some advanced techniques for characterizing lithium dendrites are summarized. Several feasible strategies for inhibiting the growth of lithium dendrites are introduced, including lithium-philic surface electrodes and heterogeneous crystal nuclei that control the nucleation of lithium dendrites, three-dimensional conductive substrates and physical coatings that control the growth of lithium dendrites, and nanostructured electrolytes with fixed anions and water-in-salt electrolyte forming spherical lithium deposits. Finally, some challenges and prospects are put forward, and the future research direction of lithium dendrites is clarified.

Plastic “white pollution” has attracted more and more people's attention. Biodegradable materials that can degrade into carbon dioxide, water and inorganic substances under the action of microorganisms in nature are an effective way to solve the problem. The development of new biodegradable polyesters heavily relies on the understanding of the biodegradation performances of the materials and support of the evaluation methods. Herein, we focus on the progress of study on biodegradable polyesters and their biodegradation, as well as polyester-degrading microorganisms and enzymes. The biodegradability evaluation methods in soil, compost, and aquatic environment are also summarized. It can be seen that low cost and high performance are highly required for developing biodegradable polyesters. The existing polyester-degrading microorganisms and enzymes are still not applicable for industrial application for polyester recovery. Highly efficient and more stable enzyme technologies are required. In addition, current biodegradability evaluation methods are time-consuming. They are substantially influenced by inoculation environments, and can’t completely reflect biodegradation in natural environment. The development of new biodegradable polyesters is also in urgent need of reliable and rapid methods for degradability evaluations.

Due to the good control ability in fluid flow, mass transfer, heat transfer and reaction, microchemical technology has become an important development area of chemical engineering. The research progress of multiphase flow and mass transfer in microchannel system based on the application of CO₂ is reviewed. Based on the fluid flow and mass transfer mechanism, the kinetic and results of mass transfer in microchannels by physical absorption and chemical absorption are introduced respectively. The application progress of resource utilization of CO₂ is summarized. The development of microchemical engineering technology towards carbon dioxide absorption and mass transfer are prospected.

The amount of urban and industrial sewage generated in China has reached 7.34×10¹⁰ t/a, and the number of sludge produced by its treatment has reached 7.29×10⁷ t/a. The main utilization methods of sludge are land application, incineration for power generation and for building materials. Heavy metals, especially Cr, Cu, Zn, Ni etc., have a great impact on these reuse processes. The sludge treatment mainly adopts pyrolysis technology. Heavy metals are concentrated in the pyrolysis residue during the pyrolysis process. Explaining the speciation distribution of heavy metals in the pyrolysis residue is of great significance to the reuse process. Based on the modified European Community Bureu of Reference (BCR) sequential extraction method, the speciation distribution of heavy metals in the sludge pyrolysis residue is summarized, the effect of pyrolysis conditions (pyrolysis temperature, residence time and catalyst), co-pyrolysis and pretreatment on the speciation distribution of heavy metals in the pyrolysis residue is described, and the future research trends of heavy metals in sludge pyrolysis residues are discussed.

The good controllability of microfluidic technology provides a new way to prepare high-throughput monodisperse bubbles or droplets. The flow behavior of bubbles and droplets has a great application prospect in the field of materials and has attracted attentions. The research progress on the self-organization behavior of bubbles and droplets in microchannels in recent years is reviewed. The self-organized lattice of bubbles and droplets has periodic flow characteristics, and the self-organization behavior is affected by dispersed phase volume fraction, the size of the droplet or bubble, coalescence effect and channel configuration. The key scientific problems to be solved in the research of self-organization behavior of droplets or bubbles are prospected, which provides a reference for further simulation and experimental research.

Based on the laminar Hagen-Poiseuille law of fluid dynamics, the liquid viscosity of high-density hydrocarbon fuel JP-10 was measured by a two-capillary method. The measured temperature range was 326.6—671.2 K and the measured pressure was 2.0, 3.0, 4.0 MPa. The extended relative uncertainties of the measured dynamic viscosities were identified as 2.88%—4.96% (coverage factor k=2). The experimental system was calibrated by measuring the dynamic viscosity of the pure substance cyclohexane. The average relative deviation between the measured results and NIST data was less than 1.22%, the maximum absolute value of relative deviation was 2.04%, and the average relative deviation between the experimental results and the recommended viscosity value is 1.25% at 2.0 MPa, 1.61% at 4.0 MPa. The absolute value of the maximum relative deviation is 3.50%, which verified the reliability of the experimental system. The viscosity value of the critical-pressure state was selected as the reference state value. By referring to the viscosity empirical formula of Yaws liquid phase organic compounds and combining with SRK state equation, the absolute rate theoretical viscosity model was improved. Coupling with the experimental data, a prediction model for the liquid-phase viscosities of hydrocarbon fuels at high-temperature and high-pressure conditions were established. The conjugate gradient method and genetic algorithm were used to fit the model parameters. The average relative deviation between the calculated results and the experimental results was less than 2.00%, and the absolute value of the maximum relative deviation was less than 4.50%, which verified the accuracy of the prediction model.

The finite element method(FEM) was adopted to study the hydrodynamics in the horizontal opposite-rotating twin-shaft kneader with different rotating speeds in a highly viscous Newtonian fluid syrup solution. The particle tracking technique was used to investigate the mixing process. The effect of kneader configuration on hydrodynamics and mixing process was analyzed. Studies have shown that there is almost no dead zone in the kneading reactor, and the flow velocity and shear rate at the end of the blade and the overlapping area are high. And the high flow velocity and high shear area increase with the increase of the number of kneading bars and the length of the kneading bars. The kneading bars, pushing material points into the angular position, periodically intermesh in the overlapping zone. Hence, the distributive mixing process in the kneader can be greatly enhanced. The length of stretch exponentially increases with time and with the increasing of the number and length of kneading bars. The time averaged mixing efficiency remains positive during the mixing process, which increases with the number of kneading bars. When the length of kneading bars increases, the time averaged mixing efficiency tends to increase in the beginning and then decrease.

The effect of microchannels with three-dimensional interlaced diamond structures on the mass transfer enhancement of ionic liquid 1-butyl-3-methylimidazole tetrafluoroborate([Bmim][BF₄])aqueous solution of CO₂ absorption process was studied. The main flow regimes were slug flow and broken-slug flow in this study. The influences of the gas and liquid phase flow rates, the concentration of ionic liquid on the liquid side volumetric mass transfer coefficient k_La, enhancement factor E, CO₂ absorption efficiency X and pressure drop ΔP were studied. Experimental results showed that 3D-rhombus microchannel could significantly improve the volumetric mass transfer coefficient and the absorption efficiency in comparison with the straight channel, and the enhancement factor could reach 2.1, while the increment of pressure drop is only 0.9 kPa. A new dimensionless empirical correlation for predicting k_La was proposed with good predicting performance. The volume of fluid (VOF) method was utilized to simulate gas-liquid two-phase flow to obtain the velocity vector contour distribution of continuous phase. The vortexes could be induced by the 3D-rhombus microchannel to enhance the mass transfer.

The flow patterns and transition mechanism of liquid-liquid two-phase flow in a step-emulsification microdevice with parallel microchannels are studied by using a high-speed camera system. The aqueous glycerol solutions are used as the dispersed phase, and cyclohexane with the surfactant of 3% Span 85 as the continuous phase. Four flow patterns are observed under different two-phase flow conditions: dripping-dripping, transition-dripping, jetting-transition, jetting-jetting. The diagram of flow patterns is constructed with the flow rates of the two-phase as the coordinate axes, and the transition lines of the adjacent flow patterns are obtained. The transition mechanism of flow patterns is analyzed. The influences of the viscosity of the dispersed phase on the flow patterns and their transitions are investigated. The flow patterns of the liquid-liquid two-phase flow are mainly affected by the hydrodynamic feedback effect in the chamber, the operating conditions and the physical properties of fluids. As the flow rate of the dispersed phase increases, the flow pattern in the microchannel changes from the dripping to the transition flow, and finally into the jetting. With the increase of the flow rate of the continuous phase, the flow rate of the dispersed phase that changes the flow patterns increases. As the viscosity of the dispersed phase increases, the transition lines of flow patterns move downward, the region of the dripping-dripping becomes smaller, and the region of the jetting-jetting becomes larger. Finally, using the concept of mesoscale, the dynamic effects of the non-uniform structure of liquid-liquid two-phase flow in parallel microchannels are analyzed.

The research on the bubble lift-off diameter is very important to reveal the heat transfer mechanism of subcooling flow boiling. Aiming at the cooling channel in the boiling area of ??the engine cylinder head, a rectangular experimental channel with similar hydrodynamics was designed, and a visualized experimental circulation system for supercooled flow boiling was built. To explore the influence mechanism of flow condition on the bubble lift-off diameter, an experiment was carried out by using a high-speed camera to closely observe the bubble behaviors on a horizontal aluminum heating surface under high mass flux. The influence of system pressure, wall superheat, flow velocity and liquid supercooling on the bubble lift-off diameter were studied. It was found that the bubble lift-off diameter decreased with the increase of system pressure, flow rate and subcooling degree, and increased with the increase of wall superheat. In this paper, a force balance model was established for bubble lift-off diameter. The average relative error between the predicted value of the force balance model and the experimental value was 12.25%. In order to facilitate the application of engineering field, the empirical formula of bubble lift-off diameter is established based on force balance model. The empirical formula considered more comprehensive factors and predicted the bubble lift-off diameter with an average relative error of 6.80%.

The formation dynamic of slug bubbles in slurry systems in a T-shaped microchannel was investigated experimentally. The influence of particle diameter was mainly investigated. The formation process of bubbles could be divided into four stages: filling stage, squeezing stage, transition stage and rapid pinch-off stage. In the filling stage, squeezing stage and quick pinch-off stage, the minimum width of bubble neck presents a power-law relationship with time. In the transition stage, the minimum neck width of the bubble has a linear relationship with time. The durations of squeezing and transition stages in slurry shorten with the decrease of particle diameter. The influences of the continuous phase flow rate and particle diameter on the power law index of filling stage are ignorable. However, the power law indices of squeezing and pinch-off stages and linear slope of transition stage decrease with the increase of particle diameter, while increase with the rise of continuous phase flow rate.

The breakup dynamic of bubbles stabilized by nanoparticles for the breakup process of permanent obstruction in a microfluidic Y-junction was studied. The breakup process can be divided into squeezing stage and pinch-off stage. In these two stages, the dimensionless minimum neck widths of bubbles have different power-law relationships with time. The neck dynamics of bubble breakup process shows that the particles do not affect the critical neck width for transition between the squeezing stage and pinch-off stage. But the particle layer absorbed on the bubble surface could weaken the squeeze effect of continuous phase on the neck in the squeezing stage and the extrusion effect of liquid reflux on bubbles in the corner area in the pinch-off stage, accordingly hinders the deformation of the bubble neck and prolongs the duration of bubble breakup. The pre-exponential factor m and power-law index α of bubble stabilized by particles are lower than those of ordinary bubble, nevertheless, their deviations decrease with the increase of capillary number Ca and bubble length l₀, indicating that the influence of particles on the breakup process weakens gradually. In addition, the curvature of bubble tip stabilized particles is slightly smaller than that of ordinary bubble, indicating that the effect of particles on bubble tip dynamics of the permanent obstruction process is ignorable.

On the basis of the traditional three-pitched-blade propeller, combined with the structure of the counter-current blade, a three-pitched-blade countercurrent blade is proposed to destroy or eliminate the stable symmetrical flow field structure in the stirring tank, and improve the fluid transfer efficiency and the degree of chaotic mixing. Power consumption, mixing time, chaotic characteristic parameters, flow field structure and fluid velocity distribution of up-flow pitched-blade turbine (PBTU), up-down counter-flow pitched-blade turbine (PBTC-U), down-up counter-flow pitched-blade turbine (PBTC-D) systems and the PBTC-U blade systems with different outer blades lengths were investigated through experiment and simulation research. The results showed that, the mixing time of the PBTC-U impeller was reduced from 22.0 s, 37.5 s to 16.5 s, and the power consumption was reduced by 5.6% and 12.8% at 130 r/min, compared with PBTU and PBTC-D impellers system, respectively. Largest Lyapunov exponent (LLE) value increased by 13.69% and 37.01%, respectively. Meanwhile, the results showed that the minimum power consumption and the minimum mixing time occurred with the outer blade length of 0.375D of the PBTC-U impeller. The PBTC-U impeller strengthened the random movement of the fluid through the counter-flow action of the inner and outer blades, enhanced the instability of the flow field and destroyed the symmetry fluid structure, resulting in much more unstable flow field and higher mixing efficiency. In addition, the PBTC-U impeller enhanced the fluctuation of axis velocity and radial velocity distribution, which was beneficial to improve the mixing efficiency of the system.

Four amino-functionalized SiO₂ nanospheres supported silver catalysts (Ag/AS) were synthesized in this work by adjusting the temperature of the reduction process for the AgNO₃ precursor with using ethanol as the reductant. The catalyst characterization and the catalytic performance tests clearly show the effect of liquid-phase reduction temperature on the performance of Ag/AS catalysts for hydrogenation of dimethyl oxalate (DMO) to methyl glycolate (MG). X-Ray diffraction, N₂ physical adsorption, transmission electron microscopy and X-ray photoelectron spectroscopy measurements indicate that the particle size of Ag particles increases significantly with the increasing reduction temperature, which results in increase of surface Ag coordination number. In-situ infrared spectroscopy of DMO adsorption and DMO temperature-programmed desorption experiments show that the increase in the coordination number of surface atoms caused by the increase of reduction temperature weakens the adsorption of DMO on the catalyst and thus reduces the activity of DMO hydrogenation to MG.

To improve the activity of Ni/SBA-16 catalyst in CO methanation at low temperature, Ni-Fe/SBA-16 bimetallic catalyst was prepared by introducing Fe promoter. The results of XPS, XRD, HRTEM and EDS-mapping characterization of the catalyst show that the addition of Fe forms a Ni₃Fe alloy with Ni, which reduces the size of the metal particles and reduces the average particle size of the metal particles from 60 nm to about 30 nm after reduction. Meanwhile, the H₂-TPR results showed that the formation of Ni₃Fe alloy strengthened the metal-support interaction, which would weaken the agglomeration of metal particles during the process of reduction and reaction. Finally, the analysis of CO-TPD and H₂-TPD indicated that the formation of Ni₃Fe alloy promoted the dissociation of reactant gas (CO and H₂), thus enhancing the catalytic activity of CO methanation catalyst at low temperature. As a result, the CO minimum complete conversion temperature was lowered to 250°C from 300°C with a CH₄ selectivity of 90% eventually at the condition of space velocity 150000 h^-1, P=0.1 MPa, V(H₂)∶V(CO)∶V(N₂)=3∶1∶1.

The H₂S and CO₂ mixed acid gas is converted into syngas in one step, which not only realizes the harmless treatment, but also produces syngas, and it is an ideal new route for waste gas resource utilization. Nevertheless, it has not been paid enough attention due to highly thermodynamic stability and kinetic inert of H₂S and CO₂. Non-thermal plasma has an advantage over the thermal processes in enhanced conversion because of its non-equilibrium feature. In this work, we demonstrated a low-temperature and novel non-thermal plasma method aided by ZSM-5 catalysts having different Si/Al molar ratios for syngas production from the simultaneous conversion of H₂S and CO₂ acid gases. The effects of Si/Al molar ratios and discharge conditions were investigated. Especially, the ZSM-5 catalyst with Si/Al molar ratio of 80 showed the best catalytic behavior. The best yields of H₂ and CO were 56.1% and 10.0%, respectively. Meanwhile, comparison of the chemisorption behaviors of CO₂, H₂S, CO and H₂ on various ZSM-5 catalysts in non-thermal plasma with those in conventional conditions were studied. It indicates that non-thermal plasma can enhance the amount of CO₂, CO and H₂ adsorbed on the catalyst surface, thus assisted in the simultaneous conversion of H₂S and CO₂.

The pressure drop is an important indicator to measure the pros and cons of the fixed bed reactor, which directly affects the reaction performance and comprehensive energy consumption. The shape and size of the catalyst particles are the key factors affecting the pressure drop of the fixed bed reactor. In this work, the effect of hollow structure of honeycomb catalyst pellets (one type of pellets commonly used in the industry) on the pressure drop in packed bed reactors is investigated by using particle-resolved computational fluid dynamics (PRCFD). Firstly, the PRCFD model built in this work is validated by comparing with the voidages and pressure drops obtained from experiments. The deviation between the pressure drops calculated by PRCFD model and obtained from experiments is less than 5%, proving the rationality and accuracy of the PRCFD model. Then, the effect of pore number is investigated. The results show that pore number only very slightly affects the voidage but significantly affects the pressure drop under the same volumes of pore and catalyst. With the increase of pore number, the pressure drop goes up, as the loss of momentum is higher when fluid flows through a smaller pore. Eventually, the effect of pore structure of a Raschig ring catalyst pellet is studied. The voidage and pressure drop can be significantly regulated by adjusting outer cylinder radius, inner pore radius, and height. When the wall of the Raschig ring is thinner, the voidage is higher, resulting in the lower pressure drop. This work can provide a powerful model and some theoretical guidance for the optimal design of catalyst pellet shape.

The COS hydrolysis and sorption catalyst was prepared by exhausted activated coke (EAC) produced in the activated coke purification process in the moving bed. Combining with the results characterized by multiple methods (XRD, TG, BET, TPD, FTIR, SEM, and XPS), it was found that the more developed pore structures and more abundant surface groups appeared in the EAC, and the specific surface area reached 445.38 m²/g. The effects of different alkali loading and process parameters on COS catalytic hydrolysis efficiency were investigated, and the results showed the activity was strongest when the NaOH loading was 0.450% at 100℃ which the breakthrough sulfur capacity reached 126.58 mg/g. The analysis of the sample after reaction showed that the COS mainly exists as S in the waste coke. This sulfur fixation method increases the sulfur capacity and provides a new way for the cascade utilization of waste coke and sulfur resource utilization.

For a single reaction tube in a tubular fixed bed reactor, the kinetic equation of CO oxidative coupling to dimethyl oxalate obtained under close to industrial conditions is used to establish a one-dimensional and two-dimensional pseudo-homogeneous model. The results of the single-tube experiment are compared, and the results show that the one-dimensional pseudo-homogeneous reactor model can more accurately describe the CO coupling reaction in the single-tube reactor. Furthermore, the effects of operating parameters on hot-spot temperature, reaction conversion, product selectivity and pressure drop were investigated by simulation with one-dimensional pseudo-homogeneous model. Then the sensitivity of reactor hot-spot temperature to operating parameters was carefully analyzed. The results show that coolant temperature has the most significant influence on the hot-spot temperature as well as the conversion of methyl nitrite, thus should be strictly controlled. The gas hourly space velocity low as 2000 h^-1 gives rise to temperature run-away in the reactor. The effects of inlet pressure, feed gas temperature and reactant composition on hot-spot temperature are relatively less. In order to increase the capacity of the coupling reactor and enhance the heat transfer effect in the bed, the feed space velocity can be increased to 4000 h^-1. At the same time, the compressor energy consumption can be reduced by increasing the reactor inlet pressure to 500 kPa. The research results can provide guideline for the process revamp and optimization of the existing industrial parallel tubular reactor for CO oxidative coupling.

Reaction characteristics and kinetics of biochar gasification with steam at temperature(T) of 1123—1223 K and steam partial pressure(SP) of 10%—40% were studied by a micro fluidized bed reaction analyzer (MFBRA). It shows that increasing T and SP was beneficial to shorten reaction time and increase the production of gaseous product (H₂, CO and CO₂) and total C conversion. At low temperature (1123 K), gasification reaction was greatly affected by SP, especially for H₂ with an increase of 1.97 times. At 1223 K and SP≥20%, due to the limitation of active sites, SP had little effect. With the increase of T, the volume yield ratio of CO/CO₂ showed a trend of first decreasing and then increasing; at 1123 and 1173 K, with the increase of SP, the ratio decreased; while at 1223 K, it basically maintained at 1.25. The generation active energy(E_a) of H₂, CO₂, and CO under different SP was calculated via shrinking core model, which were in the range of 95.44—101.82, 83.56—89.35 and 70.41—74.86 kJ/mol. The E_a of total C conversion was in the range of 71.29—76.78 kJ/mol. The test results make up for the limitations of existing analyzers that are difficult to determine the gas product generation characteristics and kinetics during the gasification process.

Pressure swing adsorption (PSA) is one of the most common technologies to produce high-purity hydrogen in the industry. However, in the actual production process, the distribution state of each component in the bed at different time cannot be observed. For this reason, simulation methods are used to study the dynamic change of each component in the bed from the feeding to the system reaching the steady state, which is essential to guide process improvement. In this study, an eight-bed PSA process was designed to purify hydrogen from steam methane reforming (SMR) gas and the activated carbon and 5A zeolite were used as adsorbent. The start-up procedure of PSA hydrogen production was performed, and the transient adsorption behaviors of each component in the bed during the three stages of adsorption, sequential release and flushing, as well as the transient adsorption behavior during the adsorption stage and the temperature variation in the bed after the system reached the cyclic steady state were analyzed. The results show that the heavy components move towards the top of the bed with the cycle during the adsorption as well as the sequential release. This phenomenon is the result of both inter-component competition for adsorption and the accumulation of fractions at the bottom of the bed in the flush regeneration mode. These factors can also, to some extent, cause the adsorption front of CO to enter too much on the 5A zeolite during the adsorption phase, making the CO content become a major limiting factor for process performance.

ZIF-8/2-methylimidazole-ethylene glycol-water slurry was used for separating CO₂ from CO₂/N₂ in a pilot-scale packed tower. In order to evaluate the tower efficiency and energy consumption of the packed tower in the CO₂ capture process, firstly, the binary interaction parameters k_CO2 of CO₂ and ZIF-8 slurry were fitted by Peng-Robinson equation of state. Then the binary interaction parameters were related to Aspen Plus to simulate the multi-stage absorption process of CO₂/N₂. The calculation results show that in the pilot-scale packed tower, with only 5 theoretical plates, ZIF-8 slurry could reduce the CO₂ concentration from 20%(mol) to less than 2%(mol), indicating the tray efficiency of the packed tower is 25%. About the energy consumption for the separation of CO₂/N₂ in the pilot plant, the results indicate that when desorption conditions were set at 333 K, 0.8 MPa, and 200 L/h, the CO₂ capture equivalent work can be as low as 0.474 GJ/t CO₂. When ZIF-8 slurry and MEA (30%(mass)) aqueous solution were used for CO₂ capture under the same conditions, the CO₂ capture equivalent work are 0.507 GJ/t CO₂ and 0.957 GJ/t CO₂, respectively. The CO₂ capture equivalent work of ZIF-8 slurry is only 53% of that of MEA aqueous solution.

Divided wall column (DWC) is a new energy-saving distillation technology. However, its optimal design is a mixed integer nonlinear programming (MINLP) problem, and it is difficult to optimize the solution. In this paper, an online Kriging surrogate model-based optimization method is proposed and applied to the total annual cost optimization of DWC. Through the proposed method, the optimal solution of the optimization problem can be obtained by a small number of rigorous simulation data points. The solution of an illustrating example shows that, compared with the traditional offline surrogate model-based optimization method, the proposed method is more advantageous in terms of accuracy and effectiveness, being able to overcome the shortcomings of the traditional offline surrogate based-model optimization, such as time-consuming and large amount of calculation.

In the chemical process, mastering the change trend of key process parameters has a great effect on eliminating potential fluctuations and maintaining stable working conditions. However, traditional shallow static models are difficult to accurately predict complex sequence data with significant nonlinearity and dynamics. In response to the above problems, a deep prediction model called TA-ConvBiLSTM is proposed by seamlessly integrating convolutional neural networks(CNN) and bi-directional long short term memory(BiLSTM) into a unified framework. In this way, the integrated model can, not only automatically explore the esoteric relevance among high-dimensional variables at each time step, but also adaptively extract useful deep temporal features across all time steps. In addition, the temporal attention(TA) mechanism is further introduced to increase the weight of significant information reflecting the law of target variation, so as to prevent it from being concealed due to the overlong input sequence and over many deep features. The effectiveness of the proposed method is verified in a case of furnace tube temperature prediction in a domestic delayed coking unit.

The currently reported β-tyrosine production method requires complex substrates and mostly rely on precious metal catalyst. To solve this, an artificially designed cascade reaction was set up by cascading TPL tyrosine phenol lyase (TPL) and tyrosine amino mutase (TAM) to synthesize (R)-β-tyrosine, with cheap compounds (phenol, pyruvate acid and ammonium salt) as substrates. These two enzymes were screened by gene mining and the catalytic efficiency of rate limiting enzyme was improved by protein engineering. The screened enzymes were co-expressed in E. coli host, and the best (R)-β-tyrosine synthesis strain E. coli S10 was obtained after optimization. In 1 L scale reaction, (R)-β-tyrosine was synthesized with 78% conversion and >99% ee. The molecular weight and structure of the purified product were identified by high resolution mass spectrometry (HRMS) and nuclear magnetic resonance (NMR), which further verified that the cascade system can be used for the synthesis of (R)-β-tyrosine. This study provides a theoretical guidance for the green enzymatic production of (R)-tyrosine.

In this study, a micro fluidized bed reaction analyzer (MFBRA) was used to examine the reaction characteristics of tar steam reforming and thermal cracking in the temperature range of 750—950℃ and steam partial pressure (SP) of 10%—30%. The production of gaseous products and the conversion of total carbon in the gaseous products and the conversion of tar were completely analyzed. The reaction kinetics was also calculated. The results show that during tar thermal cracking, with the increase of reaction temperature, the yields of H₂, CH₄, CO and CO₂ and the conversion of total carbon in the gaseous products increased, and the reaction time decreased. However, in the process of tar steam reforming, by raising the reaction temperature, the reaction time was prolonged largely, and the yields of H₂, CH₄, CO and the conversion of total carbon in the gaseous products increased significantly, while that of CO₂ reached the maximum value at 850℃. During this process, it included not only tar thermal cracking but also the reforming reaction between tar components and the reaction intermediates. At 950℃ and SP of 30%, the conversion of total carbon in the gaseous products reached 92.34%. For the tar steam reforming, with the increase of SP, although the yields of gas components and the conversion of total carbon in the gaseous products increased, the corresponding reaction rate decreased. At the same reaction temperature, with the increase of SP, the generation rates of CO, CH₄ and the rate of total carbon conversion in the gaseous products increased, the H₂ reaction rate gradually decreased with a long stable zone, while the CO₂ reaction rate reached its maximum value at 850℃. The activation energy (E_a) of the gaseous products (H₂, CO, CO₂ and CH₄), the conversion of total carbon in the gaseous products and the tar conversion were 90.10, 42.01, 58.56, 64.92, 61.44 and 63.26 kJ/mol, respectively. The corresponding values were obviously less than that of tar thermal cracking. It indicated the promotion effect of steam on tar conversion. Finally, the tar thermal cracking kinetics data was compared with the literature data to verify the feasibility of the MFBRA tar steam reforming reaction test and the accuracy of the analysis results.

Lithium-ion batteries using lithium iron phosphate (LFP) as the cathode material are widely used in electronic products, electric vehicles and other fields, but their energy density still needs to be improved to further meet the application needs of different scenarios. The diffusion of lithium ions in the electrolyte through the pores of the positive electrode is one of the key factors dominating the performance of LFP lithium-ion batteries. The diffusion resistance of the lithium ions can be reduced by certain extent by optimizing the electrode porosity, hence the energy density. In this paper, a quasi-two-dimensional model is used to describe the electrochemical process of the lithium-ion batteries with positive electrode of both gradient and uniform porosities. The influence of gradient porosity of electrode on the energy density of the lithium-ion battery is investigated. A comparison was made between the simulation results with porosities of uniform and gradient distributions. It is found that the introduction of gradiently distributed porosity into electrode coating can improve the utilization ratio of unit active material and increase both the electrolyte flux and the amount of lithium intercalation in the active material, therefore effectively increase the energy density of the lithium-ion battery. Especially, for the thick electrode coating, the enhancement in energy density is more significant with greater gradient porosity. These findings are of great importance for the preparation process of thick electrode slice.

Iron-based oxygen carrier aided oxy-fuel fluidized bed(FB) combustion replaces the traditional inert bed materials with oxygen carrier. The iron-based oxygen carrier expands the function of the “heat carrier” of the traditional bed material, and also assumes the role of the “oxygen carrier”, providing a new idea for adjusting the oxygen distribution in the furnace to match the coal combustion process. The combustion characteristics and kinetics of anthracite coal char and three types of iron-based oxygen carriers (pure Fe₂O₃, hematite, and steel slag) aided combustion of anthracite coal char were investigated in a thermogravimetric analyzer with the temperature range of 30℃ to 1100℃ at a heating of 10℃/min, 15℃/min and 20℃/min under a 10%O₂/90%CO₂ atmosphere. It is observed that the combustion behavior of anthracite coal char is much improved with the aid of the iron-based oxygen carriers, for instance, the combustion rate increases from 2.84%/min to 3.66%/min, 3.83%/min, 3.72%/min, the burnout temperature decreases from 878℃ to 803℃, 802℃, 810℃, and the comprehensive combustion index increases from 3×10^-8 %²/(℃³?min²) to 6.39×10^-8 %²/(℃³?min²), 6.21×10^-8 %²/(℃³?min²), 6.08×10^-8 %²/(℃³?min²) for pure Fe₂O₃, hematite and steel slag aided combustion, respectively. The results of kinetics analysis indicate that there is a compensation effect between the activation energy and the pre-exponential factor for the oxygen carriers aided combustion of anthracite coal char. Among three types of iron-based oxygen carriers, pure Fe₂O₃ is slightly better than hematite and steel slag in improving the combustion characteristics of anthracite coal char. Steel slag can be used as a bed material instead of quartz sand for iron-based oxygen carrier aided oxy-fuel fluidized bed combustion.

In order to clarify the pyrolysis characteristics of actual paper mill solid waste under the real component ratio and the influence of the synergistic effects between the components on its pyrolysis behavior, the real ratio of the components of the actual paper mill solid waste was determined by manual sorting. Besides, combined with DG-DAEM kinetic analysis, TG-FTIR and Py-GC/MS experiment were performed to systematically investigate the influence mechanism of the synergistic effects between the components on its pyrolysis behavior and the distribution of main pyrolysis products of paper mill solid waste. The results showed that the synergistic effects of its components had a significant impact on the pyrolysis process of actual paper mill solid waste. The synergistic effects of the components were not only conducive to the release of volatiles in the pyrolysis process of paper mill solid waste, but also could effectively promote the generation of small molecules like CH₄. Further kinetic analysis showed that the degradation reaction was dominant during the pyrolysis process of mixture sample of paper mill solid waste. In addition, at different temperatures, the experimental value of the relative content of hydrocarbons in the main liquid pyrolysis product distribution of the mixture sample was always higher than its theoretical value, while the experimental value of the relative content of the total oxygen-containing components was always lower than its theoretical value. The synergistic effect between the components of the mixed sample is beneficial to the deoxygenation of oxygen-containing components in the pyrolysis product and the conversion to hydrocarbon products.

A serial of Zr modified montmorillonites were prepared by mechanical ball milling and their characteristics were depicted by X-ray diffractometer (XRD), N₂ adsorption-desorption instrument (BET), temperature-programmed desorption of ammonia (NH₃-TPD). Then, the effect of Zr catalysts on tar quality and product distribution during coal pyrolysis was investigated in a fixed bed reactor. Finally, the pyrolysis performance of phenyl benzyl ether (BPE), bibenzyl and biphenyl model compounds of coal, were carried out to explore the breakage mechanism of covalent bonds in coal. The results show that in comparison with raw montmorillonite, the specific surface area of acid leaching sample increases, while a first decrease and then an increase trend is observed with increasing Zr content. In view of total acid sites and strong acid sites, the maximum value appears when ZrO₂ content is 24%(mass) (24ZrAM). Under the action of xZrAM, both the tar yield and pitch content decrease to a certain degree. Specially, 24ZrAM shows the highest catalytic activity, resulting in the highest light fraction of 53.2%(mass), the content of long-chain hydrocarbon decreases by 22.1% and phenolic compounds increases by 22.5%. The conversion rates of BPE, dibenzyl and biphenyl were 87.2%, 63.2% and 31.3% higher than those without catalyst, respectively, indicating that 24ZrAM can promote the cleavage of long-chain hydrocarbons and the cleavage of C_al—O, C_al—C_al and C_ar—C_ar bonds.

The energy utilization of furfural residue is an effective way for clean generation and carbon reduction in furfural industry. However, the existing direct combustion and utilization often face problems such as serious ash sintering caused by high K of furfural slag, large SO_x emissions caused by high S, and low combustion efficiency caused by high water content. To solve these problems, in this study, a tubular furnace was employed to research the sintering behavior of furfural residue ash in the pure (N₂, CO₂, O₂) and mixed (N₂+H₂O, CO₂+H₂O, O₂+H₂O) atmosphere at different temperatures. The variations of ash color, shrinking rate, micromorphology, mineral compositions and K/S release characteristics were systematically analyzed. The results show that with the increase of temperature, the ash sample shrinking rate increased. Steam played important promotion roles in ash sintering. SEM analysis indicated that the ash microstructure was melted and slaged at low temperature before sintering. XRD analysis displayed that ash sintering was closely related to the composition change of ash. N₂ promoted the composition of microcline, CO₂ inhibited the composition of microcline, while O₂ strengthened the formation of anorthite and diopside. Steam promoted the formation of various potassium aluminum silicates such as microcline and leucite. XRF analysis indicated that, with the increase of temperature, G_K (retention rate of K) and G_S (retention rate of S) in ash decreased. In pure atmospheres, G_K was the smallest in N₂, while the effect of pure atmosphere on G_S was limited. In the mixed atmospheres, compared to G_K, the effect of atmospheres on G_S was much more obvious, especially in O₂+H₂O. To restrain ash sintering and migrate K and S, the suitable operating conditions of furfural residue combustion in fluidized bed should be at temperature below 900℃ and lower N₂ content in atmosphere by introducing a stream of flue gas.

Thermoplastic polyamide elastomers (TPAEs) have attracted extensive attention in both academia and industry due to their excellent resilience and carbon dioxide permeability. Hydrogen bond has significant influence on the phase-separated structure and mechanical properties of polyamide elastomers. In this work, a TPAE comprised of long-chain PA1212 and poly(propylene glycol)-poly(ethylene glycol)-poly(propylene glycol) was used to investigate its molecular motion and hydrogen bond during heating process by in situ FT-IR, 2D correlation FT-IR, in situ WAXD and molecular dynamic simulation. Upon heating, the mobility of the molecular chain is enhanced and the hydrogen bond of the system is weakened. The hydrogen bond between C—O—C and N—H dissociates prior to that of PA1212, whose ordered hydrogen bond transits to disordered hydrogen bond. The in situ WAXD results show that d₁₀₀ is more sensitive to heat than d_010/110 and that these two lattice distances are equal finally, where the Brill transition occurs. The WAXD results suggest that the dissociation of the hydrogen bond is promoted by heating. Molecular dynamic simulation verified the results by FT-IR. The simulation results show that hydrogen bond decreases with the increasing of its bond length during heating and that the density of hydrogen bond in the PA1212 domain is higher than that in polyether. The hydrogen bond of polyether chains reduces before that of PA1212.

Through 3D printing technology, a microfluidic channel capable of spinning core-shell calcium alginate microfibers was quickly prepared, and precise control of the fiber morphology and structure was achieved. The effects of three phase flow rates, solution viscosity, channel height and undertake tube length on the morphology and structure of the prepared fibers were studied. The experimental results show that compared with other methods, the 3D printing method is more convenient and stable for the preparation of spinning channels, and the batch stability of the channels is high, so it is suitable for the mass production of microfibers. For the morphology control of the fibers, increasing the outer phase velocity can reduce the fiber diameter, increasing the middle phase velocity can increase the shell thickness, and increasing the inner phase velocity can increase the diameter of the nucleus. The change of solution viscosity has little effect on the fiber morphology. The greater the distance between the outlet of the microchannel and the solidification liquid, the thinner the fiber. If the length of the receiving tube is too short, the fiber will be uneven. The core-shell structure of fibers makes it easy to load functional substances and has potential application in the field of drug delivery.

In the application of all-solid-state polymer electrolyte (SPE), the bottleneck is how to meet the requirements of ion conductivity and mechanical strength simultaneously. Aiming at the above problem, this paper adopts the reversible addition fragmentation chain transfer (RAFT) solution polymerization technology to synthesize SPEs with different chain structures. The SPEs apply the cyclohex-3-enylmethyl acrylate (CEA) as post-crosslinking monomer and the poly(ethylene glycol) methyl ether acrylate (PEGMA) as ion-conducting monomer. A chemically cross-linked network structure was formed by the “click chemistry” reaction between the double bond on the cyclohexene in CEA and the mercaptan. The prepared triblock copolymer electrolyte has independent ion-conducting blocks while the crosslinking monomers concentrating at both ends of the molecular chain, thus meeting the demands of mechanical strength and ionic conductivity simultaneously. The prepared triblock copolymer electrolyte presented ionic conductivity of 6.13×10^-5 S/cm at 60℃. The lithium iron phosphate/lithium (LiFePO₄/Li) all-solid-state battery using the prepared triblock copolymer electrolyte presented specific discharge capacity of 139.1 mAh/g after 130 cycles at 0.5 C. The retention rate was 97.8% while the coulombic efficiency remained above 99.0%, showing good electrochemical performance.

The effects of component concentration and equivalence ratio on the explosion characteristics of hydrogen/dimethyl ether/methane ternary mixed gas fuel were systematically studied by using the constant volume combustion bomb explosion experimental platform and high-speed schlieren camera technology. The results show that the average flame propagation speed S_a increases monotonically with the increase of hydrogen concentration X_{{\mathrm{H}}_{\mathrm{2}}} and decreases monotonically with the increase of dimethyl ether concentration X_DME. Also S_a decreases monotonically with X_{\mathrm{C}{\mathrm{H}}_{\mathrm{4}}}. The variation of explosion pressure peak p_max with X_{{\mathrm{H}}_{\mathrm{2}}} is strongly affected by equivalence ratio φ. When φ= 0.8, 1.0 and 1.2, p_max increases slowly and linearly with X_{{\mathrm{H}}_{\mathrm{2}}}, and then increases rapidly with X_{{\mathrm{H}}_{\mathrm{2}}}; While when φ=0.6, 1.4 and 1.6, p_max continuously increases linearly with X_{{\mathrm{H}}_{\mathrm{2}}}. Meanwhile, p_max decreases linearly with the increase of X_{\mathrm{C}{\mathrm{H}}_{\mathrm{4}}}, but p_max can be divided into two periods with the change of X_DME. In addition, X_{{\mathrm{H}}_{\mathrm{2}}} is positively correlated with the maximum pressure rise rate (dp/dt)_max, and X_{\mathrm{C}{\mathrm{H}}_{\mathrm{4}}} is negatively correlated with (dp/dt)_max. However, X_DME has little effect on (dp/dt)_max. The combustion time t_c has a linear relationship with X_{{\mathrm{H}}_{\mathrm{2}}} and X_{\mathrm{C}{\mathrm{H}}_{\mathrm{4}}}. Conversely, the influence of X_DME on t_c is more complicated, which is related to φ.

In order to study the suppression characteristics of ammonium polyphosphate(APP) on polymethyl methacrylate(PMMA) dust explosion, the effects of APP on PMMA dust explosion characteristics were analyzed from the aspects of explosion pressure, explosion pressure rise rate, minimum ignition energy(MIE) and minimum ignition temperature(MIT). The results show that APP can effectively reduce the maximum explosion pressure and explosion pressure rise rate of PMMA dust, and delay the arrival time of explosion pressure peak. For MIE with different concentrations of PMMA dust, APP has a significant inhibition effect, and there is a critical inhibition concentration ratio of 1∶1. Under this concentration ratio, PMMA dust is difficult to ignite through electrostatic ignition. APP also has a certain inhibitory effect on MIT with different concentrations of PMMA dust, and the suppression effect increases with the increase of PMMA concentration under the condition of the same concentration ratio. In addition, combined with the thermal characteristics and infrared spectrum analysis results of APP and PMMA, the mechanism of APP inhibiting PMMA dust explosion is analyzed. The inhibition mechanism of APP on PMMA dust explosion includes physical and chemical effects. The physical effect is mainly caused by APP decomposition endothermic and delays the decomposition rate of PMMA. The chemical action is mainly due to the decomposition of APP, produces a large number of active groups that can consume the active free radicals generated in the process of PMMA explosion, which can reduce the chain reaction rate or interrupt the chain reaction, and then inhibit PMMA dust explosion. In addition, combined with the thermal characteristics of APP and PMMA and the results of infrared spectroscopy, the mechanism of APP inhibitingPMMA dust explosion was analyzed.

Foam extinguishing agent is one of the commonly used fire fighting methods, but conventional foam extinguishing agent has a short half-life, liquid separation and rapid accumulation, which affect the fire extinguishing efficiency. Based on fire chemistry and active agent technology, a ternary system of hydrocarbon surfactant SDS, silicone surfactant LS-99 and low carbon alcohol was proposed and the compounding ratio of hydrocarbon/silicone/low carbon alcohol was systematically investigated. The critical micelle concentration of LS-99 was found to be 0.0083% by extensive testing of surface tension, foaming height and foam stabilization coefficient. LS-99 and SDS binary systems have good synergistic effects in terms of reducing surface tension, increasing foam height and foam stabilization coefficient. Based on this foundation, a hydrocarbon/silicone/low carbon alcohol foam extinguishing agent has been designed by introducing an appropriate concentration of isobutanol, which retards foam precipitation and polyhydration. At 0.1% mass concentration of LS-99, SDS and isobutanol, the test results show that the SDS/LS-99/alcohol ternary foam has a foaming multiplier of 52.5 times, a 25% drainage time of 210 s and a stability coefficient of 0.958 at 300 s, with a half-life far exceeding that of conventional foams. Fire suppression experiments on coal spontaneous combustion show that the activation energy of all reaction stages of coal spontaneous combustion under the action of SDS/LS-99/alcohol ternary foam increases compared to the air atmosphere, and the difficulty of the reaction increases; the maximum mass loss rate decreases and the intensity of the reaction decreases. The heat absorption in the initial heat absorption phase is 78.3 J/g, which is greater than the heat absorption of the coal sample in the air atmosphere, with an increase in heat absorption of up to 2.16 times. The heat release in the exothermic phase was 1765.4 J/g, a reduction of 15.15% compared to the exothermic air atmosphere, which indicates that the SDS/LS-99/alcohol ternary foam has a good extinguishing effect on spontaneous coal combustion.