Lithium and its compounds are important strategic resources for the national economy and national defense construction. It has important applications in the fields of energy storage batteries, fine chemicals, and atomic energy thermonuclear fusion. China is a major consumer and producer of lithium resources, but our lithium consumption is more than 70% dependent on foreign sources. At the same time, lithium resources in China are mainly stored in salt lake brines in the western region. The problems of low lithium concentration and high magnesium-to-lithium ratio have increased the difficulties of lithium extraction. In view of the existing problems of lithium extraction from salt lakes in China, this article systematically summarizes the traditional methods for extracting lithium resources from salt lakes, and focuses on the important progress of new membrane separation materials and membrane separation processes in the efficient extraction of lithium from salt lake brines, especially the latest achievements made by Chinese researchers.

Perovskites have good application prospects in biomass thermochemical utilization due to their excellent redox performance, ion mobility, thermal stability and low cost. Perovskite catalysts are mainly used in biomass pyrolysis/gasification, biomass reforming and chemical synthesis of biomass downstream products. This paper focused on the catalytic performance and the catalytic mechanism of the perovskite catalysts. Furthermore, based on the catalysis of metal cations and the redox of lattice oxygen, the optimization design of perovskite catalysts were summarized from the aspects of ion substitution at A/B sites and space structure change. It points out the direction for the application and optimization of the perovskite catalyst in the field of biomass thermochemical utilization.

Under the background of advocating the green manufacturing of compounds, the use of microbial cell factories to synthesize new compounds or increase the yield of compounds is one of the important directions for the development of green chemical technology. However, the low yield of target compounds is a common problem in the synthesis of microbial cell factories. One of the effective ways to solve this bottleneck is to design biosensors in microbial cells to monitor and regulate the biosynthesis of compounds. This paper introduces the types and mechanism of intracellular biosensors in details, focusing on how biosensors are coupled with the design of product synthesis pathways in microbial cell factories to improve the fine regulation of cell factories and the ability to synthesize target products. Finally, the challenges and feasible solutions of the current intracellular biosensor design are discussed.

As a new type of heat pipe technology, oscillating heat pipe (OHP) has the advantages of simple structure, good heat transfer performance, and strong environmental adaptability. It has great application potential in heat transfer fields such as thermal management, solar heat collection, waste heat recovery, and etc. The rapid development of high heat flux devices, utilization and recovery of heat energy and other fields have put forward higher requirements for heat transfer performance and adaptability of heat transfer devices. In order to further enhance the internal two-phase flow heat transfer and adapt to different working conditions, new OHPs with various structures have been proposed. The research progress of the new structure OHP is mainly summarized from three aspects: the internal structure optimization to strengthen the thermal performance, the new external structure to meet the needs of different application requirements, and the application research of the new structure OHP. The follow-up research should design universal new structure OHPs on the basis of clarifying the operation mechanism.

Butenyl-spinosyn is an insecticide produced by Saccharopolyspora pogona, which has both the safety of biological pesticides and the quick-acting properties of chemical pesticides. However, the low synthesis efficiency of butenyl-spinosyn by wild-type strains cannot meet the need of industrial production, obtaining high-yield strains is an urgent problem. At present, there are few related studies on butenyl-spinosyn. The spinosyn produced by Saccharopolyspora spinosa has a similar structural and biosynthetic pathway. This article describes the basic characteristics of them, draws on the research experience of spinosyn, summarizes the available strategies for breeding and modifying high-yield butenyl-spinosyn strains, including mutagenesis methods and precise genetic engineering methods such as metabolic flux regulation, pathway genes regulation, transcriptional regulation, heterologous expression, which may provide ideas for further research of butenyl-spinosyn.

The saturated vapor pressure of the [Li(TX-7)]SCN/H₂O solution at 283.15—443.15 K was measured by the static method, and the specific heat capacity of the ionic liquid [Li(TX-7)]SCN under the condition of temperature T=73.15—423.15 K was measured by the differential scanning method, and an empirical correlation formula is established. The excess enthalpy of the [Li(TX-7)]SCN/H₂O solution component activity coefficient was predicted by the Wilson model, and the specific enthalpy of the binary solution was calculated by the predicted value, and the thermodynamic model of [Li(TX-7)]SCN/H₂O was established. Based on the experimental data and thermodynamic model, the theoretical cycle characteristics of the second type heat pump with [Li(TX-7)]SCN/H₂O as the working fluid pair are simulated and analyzed, the influence of different operating temperatures of various components on the performance parameters of the system is studied and compared with the performance parameters of other absorption systems. The performance of the [Li(TX-7)]SCN/H₂O system is better than that of the LiBr/H₂O system, and it is suitable for working conditions with lower generation and evaporation temperatures.

Attrition of solid particles is one of the important problems of fluidization technology. The study of particle attrition characteristics and two attrition mechanisms in the process of gas-solid flow is of great significance to the application of fluidization technology. In this paper, a visualized cold fluidized bed was designed for coal tar pitch particles to study the effects of gas velocity, initial particle size and height-diameter ratio on attrition behavior, and to discuss attrition mechanisms. The results show that the sphericity of coal tar pitch particles increases and the surface tends to be smoother after fluidization, but the average diameter decreases. The attrition process is affected by two attrition mechanisms, fragmentation and abrasion respectively. In the high-speed attrition stage, abrasion plays a dominant role, and in the low-speed attrition stage, both fragmentation and abrasion work simultaneously. In the steady state, abrasion dominates again. In addition, increasing gas velocity and height-diameter ratio, decreasing initial particle size all aggravate the attrition process. With the fluidization number increasing from 2.7 to 3.9, the rate of fragmentation and abrasion increases by 3.6% and 1.4%, respectively. When height-diameter ratio doubles, the rate of fragmentation and abrasion increases by 1.4% and 8.2%, respectively.

The heat transfer characteristics of steam condensation flow in a vacuum horizontal tube with the length of 3.4 m and inner diameter of 38 mm were studied experimentally. The steam mass flow rate is less than 9 kg/(m²·s), steam saturation temperatures are 50, 60 and 70℃, and steam inlet saturation temperature and cooling water inlet temperature difference is from 3 to 7℃. By analyzing the condensation heat transfer mechanism of stratified flow, the calculation model of thermal partition angle was established. The results of experiments indicate that the thermal partition angle increases with the increase of mass flow rate and heat transfer temperature difference. The saturation temperature has little effect on the local heat transfer coefficient and the thermal partition angle. The empirical correlation of local heat transfer coefficient is established by taking the thermal partition angle as the zone boundary. Under the experimental conditions, the predicted results in filmwise condensation area at the top of the tube are within ±25% and the predicted results in convective heat transfer zone of condensate at the bottom of the tube are from +25% to -35%.

A new proposed coaxial four-channel nozzle with a gas-liquid-gas-liquid arrangement from the center towards the wall is investigated. The liquid stream in the outer channel can isolates the syngas and oxygen in operation; the outlet temperature of the nozzle is consequentially lowered, and then its service life in gasifier is increased. Water-air system is used as the experimental medium, and the influencing factors of the nozzle on the air-blast atomization are studied by analyzing the Sauter mean diameter D₃₂ with the Malvern laser particle size analyzer. The sequence of the influences on atomization from high to low is channel 3, channel 4, channel 2 and channel 1. The atomized droplet size reduces with an increasing liquid volume distribution ratio of channel 2 to channel 4 while increases with the increasing of the outermost liquid film thickness. The effect of the gas distribution ratio of channel 1 to channel 3 on the atomized droplets is non-monotonic, i.e. the droplet size increases first and then decreases. In addition, an empirical formula for estimating the droplet size of the coaxial four-channel nozzle was obtained based on the numerical analysis of experimental results.

As a low GWP refrigerant, R32 is widely used in room air-conditioners in which the working fluid is the mixture of refrigerant and lubricating oil. In order to optimize R32 air conditioner, it is necessary to know the flow boiling heat transfer characteristic of R32-oil mixture. The purpose of this paper is to test the flow boiling heat transfer characteristics of R32-oil mixture inside tubes and develop a new correlation of heat transfer coefficient according to the actual working conditions of air conditioners. A new experiment rig with explosion-proof function was set up to test the heat transfer performance of R32-oil mixture inside tubes. Copper tube with 7 mm outer diameter was chosen as the test section, and the test conditions include the mass flux ranged from 200 to 400 kg/(m²·s), the vapor quality ranged from 0.2 to 0.7 and the oil concentration ranged from 0 to 5%. The test results indicated that, the heat transfer coefficient of R32-oil mixture increases with the increase of mass flux; moreover, the presence of oil enhances the heat transfer at the range of low and intermediate vapor qualities; there is a peak of local heat transfer coefficient at about 3% oil concentration at higher vapor qualities. A new heat transfer coefficient correlation of R32-oil mixture inside 7 mm smooth tube was developed based on the mixture properties and the flow pattern, and it agrees with 85% of experimental data within deviation of ±20%.

The flow field characteristics of dynamic step impinging stream reactor were studied by experimental and numerical simulation methods, and the fluid flow law, turbulence characteristics and energy level under different inlet velocities were analyzed. The results show that under the condition of dynamic step inlet, the impact surface moved periodically between the two nozzles, and the flow parameters also changed periodically. The stagnation velocity was increased with the average inlet velocity. With the increase of the inlet velocity difference between the two nozzles, the moving speed of the impact surface was accelerated, and the fluid turbulence intensity in the impact zone was increased gradually. With the increase of the difference between the inlet average velocity and the inlet velocity, the average turbulent kinetic energy of XOZ plane in one cycle was gradually decreased. The flow field characteristics in dynamic impinging stream reactor and steady-state impinging stream reactor were compared to explore the influence of dynamic inlet conditions on the flow field characteristics of impinging stream reactor. The results show that the parameters of turbulent viscosity, turbulence intensity and turbulent kinetic energy of dynamic step impinging stream reactor were significantly higher than those of steady-state impinging stream reactor, and the gradient distribution of turbulent kinetic energy on the impact axis was greater than that of steady-state impinging stream reactor. Under the condition of dynamic inlet, the fluid turbulence in the impinging stream reactor was more intense and the energy level was higher, which was conducive to increasing the fluid disturbance and promoting mixing in the flow field.

A cylindrical electrode is arranged at the inlet pipe of the heat exchanger and connected to the positive electrode of the high-voltage power supply to study the influence of the non-uniform electric field formed by the cylindrical electrode on the deposition of CaCO₃ fouling on the heat exchange surface of the experimental section. In comparison, the CaCO₃ scale deposition under the action of the parallel plate electrode (uniform electric field) was discussed. The results showed that applying parallel electrode and the cylinder electrode can inhibit CaCO₃ scale on heat transfer surface deposition, scale inhibition rate increased with increase of voltage (0—5000 V) firstly and then decreased. When applying parallel electrodes, the best scale inhibition voltage value is 1000 V and the best scale inhibition rate is 73.27%. When the cylinder electrode is applied, the best scale inhibition voltage is 500 V and the best scale inhibition rate is 83%. Therefore, the cylinder electrode has better scale inhibition rate, and the best scale inhibition voltage is lower which can reduce the electricity consumption. In addition, SEM analysis shows that CaCO₃ crystal is mainly dendritic aragonite structure at no electric field, while CaCO₃ crystal is mainly calcite structure under the action of the electric field.

Accurate calculation of frictional pressure drop of gas-liquid two-phase flow under fluctuating vibration is of great significance to the development of marine nuclear power. The variation of frictional pressure drop of gas-liquid two-phase flow in a 30° inclined riser pipe under different vibration and flow conditions was studied by experiment. The results show that the fluctuation amplitude and average value of friction pressure drop increase significantly under fluctuating vibration. Compared with the static state, the multi-scale entropy of friction pressure drop increases obviously except bubble flow, and the phenomenon of large-scale oscillation is present, which indicates that the instability of gas-liquid two-phase flow is more significant. The calculated results of the static friction pressure drop model are quite different from the experimental values, and the existing models are not suitable for the fluctuating vibration state. It is found that the friction coefficient is inversely proportional to the homogeneous Reynolds number and directly proportional to the vibration amplitude and frequency. Based on a large number of experimental data, the calculation formula of friction resistance coefficient suitable for fluctuating vibration state is established, and the calculation results are in good agreement with the experimental results.

Three-dimensional heat flow field characteristics of supercritical nitrogen (SCN₂) in the micro-channel was studied by combining experimental and numerical simulation methods. Based on the reliability of numerical method verified by experimental data, the effects of pressure (3.6—7 MPa) and mass flux (800—1200 kg/(m²?s)) on the convective heat transfer characteristics of SCN₂ were analyzed. The heat flux field of SCN₂ in different circumferential directions of the tube was revealed. The results show that under low pressure and high mass flux, the maximum radial inner wall temperature appears at 90° of the circular tube at the same axial position. With the increase of mass flux, the maximum inner wall temperature and the minimum heat transfer coefficient gradually shifted from 180° to 90° of tube. When buoyancy coefficient Gr*/Re²>1, the buoyancy force was conducive to enhance the fluid heat transfer capacity at the bottom of the circular tube. Based on the obtained data, a new dimensionless correlation is proposed to predict the convective heat transfer characteristics of SCN₂ in micro-channel, and the prediction error is less than 20%. The results provide a reference for the optimal design of micro-channel heat exchanger.

Solar interface evaporation can achieve high-efficiency solar desalination and evaporative sewage treatment, but most of the current research is limited to pure water or NaCl solution. The actual solute in desalination and wastewater treatment will be different, which will lead to different vapor liquid equivalent behavior of the solution and affect the evaporation performance, but the research in this area is lack. This work analyzes different vapor pressure curves of the solution with different concentration, and divides them into three types: convex type, concave type and straight type,and further selects [EMIM][OTf]/H₂O, [EMIM][Ac]/H₂O and NaCl/H₂O as representative solutions. Experiments were conducted under different irradiation intensities and concentrations, and the evaporation of pure water was compared. The experimental results show that [EMIM][OTf]/H₂O exhibits good evaporation performance under low concentration, the main reason is that its vapor pressure is in the convex region; when the concentration of the solution increases or when the irradiation intensity increases, the evaporation rate of the [EMIM][OTf]/H₂O is lower than that of the NaCl/H₂O, the reason is that the concentration polarization of the evaporation process causes the concentration of [EMIM][OTf]/ H₂O at the gas-liquid interface to increase, and the difference in vapor pressure is small; the evaporation rate of [EMIM][Ac]/H₂O is the lowest under different working condition, while the evaporation rate of pure water is the highest, which reflects the key influence of vapor pressure on evaporation performance, because low vapor pressure leads to high evaporation temperature and more energy loss.

Ammonia (NH₃) selective catalytic reduction of nitrogen oxides (NH₃-SCR) is currently the most promising diesel exhaust purification technology. The core of this technology is the development of catalysts with excellent catalytic performance. In recent years, Cu modified SSZ-13 zeolites with chabazite (CHA) topology as support have attracted extensive attention due to their excellent catalytic performance and hydrothermal stability. Therefore, in this study, a series of Cu_x/SSZ-13 catalysts with different Cu/Al ratios were prepared. The location and state of Cu ions on SSZ-13 zeolites with high catalytic activity was determined by insitu diffuse reflection infrared spectrum (DRIFT) using CO as probe molecule and H₂-TPR. By means of CO adsorption experiments, it was found that the Cu_x/SSZ-13 catalysts prepared by the ion exchange method of Cu(NO₃)₂ aqueous solution had a variety of Cu⁺ active sites. For catalysts with low Cu ion exchange degree, Cu⁺ firstly located in the micro-channel of SSZ-13 zeolites. As Cu exchange degree increased, Cu⁺ would locate in the double-six-membered ring of SSZ-13 zeolites. H₂-TPR characterization results show that there are also a large number of unstable Cu²⁺ located in the eight membered ring on Cu_x/SSZ-13 catalyst, which can be easily reduced to Cu⁺. For Cu/SSZ-13 catalyst aged by steam at 800℃ for 16 h, most of framework aluminum removed and Cu species agglomerated, both of which resulted in zeolites framework collapse. While, to a certain extent, the addition of Ce can improve the hydrothermal stability of Cu/SSZ-13 and protect the zeolites framework from collapse. The structure-activity relationship of the catalyst shows that the catalyst with a certain amount of stable Cu⁺ and a large amount of unstable Cu²⁺ has catalytic performance for NH₃-SCR in a wide temperature range.

The curing process of epoxy monomer (3EPZ) containing heteronaphthalene biphenyl structure with polyether amine (ED-2003) was investigated by differential scanning calorimetry (DSC). The activation energy and related kinetic parameters of the system at different conversion rates were obtained using the Starink model and the autocatalytic model, and the kinetic equations were established. The correlation coefficients between the experimental results and the model calculations were greater than 99%, indicating that the autocatalytic kinetic model developed can better describe the curing process of the system.

Four types of Co-supported catalysts, HZSM-5, HY, Hβ and MCM-22, were prepared by the impregnation method. In the high-pressure reactor, the prepared catalyst is used as a raw material for one-step hydrodeoxygenation of ethyl levulinate to synthesize ethyl valerate and valeric acid biofuel. X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), Fourier infrared (FT-IR), NH₃-TPD, H₂-TPR, py-FTIR, ICP-AES and other technologies are used for catalyst characterization. The results show that, because Co is uniformly distributed on HZSM-5, B acidity, total acidity and reduction performance are the best, while maintaining high reactivity, it improves the selectivity of the product. Therefore, the 10Co/HZSM-5 catalyst has higher catalytic performance. The reaction temperature, reaction pressure, etc. are further optimized. When the reaction temperature is 240℃, the pressure is 3 MPa, and the reaction is 3 h, with n-octane as the solvent, the catalyst shows higher catalytic performance, and the conversion rate of ethyl levulinate reaches 100%, the total yield of valerate and valeric acid can reach 90%.

Co-catalytic fast pyrolysis (Co-CFP) of biomass and waste plastics is an important way to produce light aromatics. In this work, co-catalytic fast pyrolysis of three major component in biomass (cellulose, hemicellulose, and lignin) and low density polyethylene (LDPE) was carried out in Py-GC/MS by using different zeolite catalysts (HZSM-5 (25), HZSM-5 (85), HY, USY and MCM-41). The effect of catalytic pyrolysis parameters on the yield of light aromatics and the synergistic interactions between biomass three major components and LDPE were investigated. The results showed that, among the five types of zeolite catalysts, HZSM-5 (25) presented highest yield of light aromatics during single CFP of poplar, biomass three major components, and LDPE. During Co-CFP of poplar and LDPE, the yield of light aromatics increased first, and then decreased with the increase of mass of LDPE. During Co-CFP of biomass three major components and LDPE, Diels-Alder reaction occurred between the pyrolysis intermediates of the furans from cellulose/hemicellulose and the light olefins from LDPE, promoting the formation of light aromatics. However, the Co-CFP of lignin and LDPE hindered the formation of light aromatics.

The synthesis gas is carbonylated with dimethyl ether (DME) to synthesize methyl acetate (MA). The further hydrogenation of MA to produce ethanol is a new and efficient route for the production of ethanol from coal-based synthesis gas. Modification of HMOR zeolite using mild post-treatment method to improve its catalytic efficiency of DME carbonylation is considered as an efficient strategy for the industrialization application. In this study, tetraethylammonium hydroxide (TEAOH) was used to modify HMOR zeolite. The effects of organic base modification on the structure and catalytic performance of DME carbonylation of HMOR zeolite were firstly discussed. It was found that when the concentration of TEAOH was 0.3 mol/L, the mesopore volume and external specific surface area of the HMOR zeolite are increased about 26% and 10%, respectively, and the conversion rate of DME is increased by 68%. The OH^- generated by the hydrolysis of TEAOH can gently remove the skeleton silicon in the HMOR zeolite and the hierarchical pore structure can be successfully obtained. The generated hierarchical pore structure is favorable to the mass transfer rate in the carbonylation reaction process of DME. In addition, the hydrolyzed TEA⁺ is enriched on the surface of HMOR zeolite, which inhibits the excessive desilication of OH^- and protects the basic skeleton structure of HMOR zeolite from further destruction.

In this study, corn straw and Pt/TiO₂ were used as sacrificial agent and catalyst, respectively. The effects of different parts and components of corn straw, pH and the addition of common cation and anion of liquid environment on photocatalytic hydrogen production were studied. X-Ray diffraction (XRD), thermogravimetric analysis (TGA) and UV-vis diffuse reflectance spectra (UV-vis DRS) were used to characterize the components and light absorption characteristics of corn straw. The results show that the hydrogen production was moderate in the range of pH=5—7, inhibited in the range of pH<5 and pH=8—10, and increased in the range of pH>10. Strong acid anions and alkali metal ions have no effect on hydrogen production. \mathrm{C}{\mathrm{O}}_{\mathrm{3}}^{\mathrm{2}-} and \mathrm{H}\mathrm{P}{\mathrm{O}}_{\mathrm{4}}^{-} promoted hydrogen production in different degrees. Fe³⁺, Cu²⁺ and Zn²⁺ have different degrees of inhibition on hydrogen production due to their strong or weak order of oxidation and weak ionization. Based on the above experimental results, the law and mechanism of the influence of different ions on hydrogen production are analyzed.

The recovery of C₂/C₃ light hydrocarbon components from natural gas has important industrial value. Adsorption separation technology can realize the recovery of light hydrocarbons under normal temperature and pressure. Tuning the secondary building unit (SBU) optimizes pore chemistry and develops new adsorption sites of MOF, while the well-defined framework can be inherited. s-Triazine (TZ) was used to replace the coordinated water molecules from the SBU of Zr-TBAPy and construct an alkaline surface chemical microenvironment that has a stronger restriction on light hydrocarbon adsorbates in its pores to obtain a highly selective TZ@Zr-TBAPy adsorbent. On the one hand, the introduction of TZ improves the surface roughness of the pores on the molecular scale; on the other hand, it strengthens the confinement effect on light hydrocarbon adsorbates, thereby increasing the adsorption capacity and selectivity for alkanes of absorbent. Under standard ambient temperature and pressure, the adsorption capacity of TZ@Zr-TBAPy for propane reaches 10.08 and 4.19 mmol?g^-1, which is 27% and 9% higher than that of Zr-TBAPy. It is currently among the top adsorbents concerning propane adsorption capacity in the world. Moreover, the IAST selectivity of propane/methane is 1518, which is 6.27 times that of raw materials; the IAST selectivity of ethane/methane is 11.7, which is 22% higher than that of raw materials. In addition, the isosteric adsorption heats of TZ@Zr-TBAPy for the three alkanes follow the propane>ethane>methane, indicating that propane has a stronger affinity than methane and ethane, which is related to the preferential adsorption of propane of the material. More importantly, the fixed-bed adsorption process with TZ@Zr-TBAPy adsorbent as the core can realize the one-step separation and recovery of ethane and propane in natural gas at room temperature and pressure.

Coal tar, a complex mixture of heteroaromatics and polyaromatics, is a by-product of coke industry and usually difficult to derive from the petrochemical industry. Therefore, the primary structure of coal tar has a great application value. To further increase the value of coal tar's primary aromatic structure, the efficient separation is essential for rupturing the intermolecular interactions of various compounds available in coal tar. The profound knowledge about such intermolecular interactions is pivotal for designing the suitable extractants. In this study, the energy range involved in the intermolecular interactions of coal tar was analyzed, and the dispersion energy range of nitrogen- and sulfur-based heteroaromatics in the liquid fuel and coal tar was obtained. The method for designing and selecting the suitable extractants in the energy range of -15~-70 kJ/mol was proposed. According to the reports focusing on the extraction of nitrogen- and sulfur-based heteroaromatics using deep eutectic solvents, the various routes for enhancing the intermolecular interaction during the extraction process were classified. This energy-based analysis would provide a new strategy to design the suitable and efficient extractants for separating the value-added chemicals from coal tar.

Catalytic cracking is the core processing technology in the current refinery. Its reaction-regeneration system is a complex system closely coupled with multiple variables. It is difficult to design dynamic simulation and control systems. At present, a large number of assumptions have been set up in the process of dynamic modeling of FCCU, which is inconsistent with the actual situation. In addition, the current control loop configuration method does not consider the process requirements and is not suitable for open-loop unstable systems such as FCC. For the above reasons, based on the mathematical model of reactor-regenerator system established by the author, this paper establishes a refined dynamic model to approximate the reactor and regenerator models, no longer ignoring the dynamic changes of gas phase, recover the derivative term of gas relative time in the original model, and through the discrete distributed parameter system model, time delay is added to the time-varying variables of each riser and coke can in the discrete model. The simulation results show that the refined dynamic model is closer to the actual chemical commercial process. Based on the above models, a simulation platform is built to design the prior process analysis based control system for the unstable reactor-regenerator system. Firstly, the control loop is configurated according to the chemical process to ensure the system stability, and then design the matching of remaining variables based on relative gain array method, which not only reduces the design complexity of the high-dimensional system, but also ensures the safety of the commercial process. The design results show that for FCCU reactor-regenerator system, after the control loop configuration is completed based on the process characteristics, the remaining variables can ensure the stability and appropriate control performance of the control system without adding additional control loops.

Multi-effect distillation (MED) technology is one of the most important seawater desalination methods. As a typical slow-time-varying system, in the process of long-term operation, the heat transfer efficiency of the evaporator is often reduced due to fouling accumulation, resulting in production reduction or even shutdown. In order to avoid this kind of problem, designers usually adopt redundant designs to increase the heat transfer area, which leads to a significant increase in equipment investment. In order to ensure that the device can effectively operate in a full cycle and reduce the total heat transfer area as much as possible, a full-cycle optimization design method is proposed. This method takes the total heat transfer area as the objective function, and uses decision variables to perform segmental optimization throughout the full-cycle. At the same time, fouling accumulation, process changes and control requirements are considered when designing heat transfer area margins of each effect. It obtains the optimal operating conditions and the minimum heat transfer area in one step, and completes the optimal design of the slow-time-varying system. Finally, taking a MED desalination system with eight effects as an example, the system is designed by using equal area method, equal temperature difference method, steady-state optimization design method, and full-cycle optimization design method at the same time. The results show that the full-cycle optimization design method can minimize the heat transfer area and greatly reduce the equipment investment of the MED system. It is a multi-effect evaporative desalination system optimization design method with good application prospects.

Modular chemical production characterized by“numbering-up”provides a new way to optimize the production process to overcome fluctuations in raw material supply and product market demand. In order to improve the energy utilization efficiency of the production system, it is necessary to store and schedule the preheating, cooling and reaction heat of the streams that change over time in the production system. For the methanol modular production system driven by renewable energy, a time-sharing heat storage strategy for modular production of methanol was proposed, in which three steps are included, i.e. setting storage tank and matching streams, determining the temperatures of heat storage and configuring the capacities of tanks. The optimal design and scheme of heat storage can be obtained. The results showed that the time-sharing heat storage system can allocate the thermal energy in the previous stage to use in the subsequent stages in the methanol production system, which can maximize the utilization of energy in the system. The appropriate amount of heat storage can reduce the investment of the heat storage system cost. The proposed optimization method for heat storage systems can provide practical tools for analysis of the optimal design of the time-sharing heat storage system in the fluctuating production processes.

Near-infrared spectroscopy is used to on-line detect the product purity of distillation purification process of 2,6-dimethylphenol (2,6-DMP) monomer separation section. Because the product purity of the 2,6-DMP product tower is relatively high (usually 99.10%—99.95%), the purity value of the samples is concentrated in a small range, the coefficient of variation between samples is small, the discrimination of NIR spectrum is low, and the correlation between NIR spectrum and physical property concentration is small, a reliable model cannot be established. To accurately detect the product purity of the 2,6-DMP product tower, thereby real-time control of the product quality, the migration learning algorithm is introduced to make full use of the similarity of the near-infrared spectroscopy data between the different towers in the 2,6-DMP distillation and purification process. With the help of the near-infrared spectroscopy data of the lower 2,6-DMP purity in other towers, the performance of the near-infrared model of the higher 2,6-DMP purity in the product tower is improved. Finally, the validity of the method is verified by establishing near infrared on-line detection models for the purity of 2,6-DMP in a synthetic material company. The results show that with the help of NIR data of different number and purity range, the accuracy of the purity model after transferring is different. It illustrates that the transfer learning algorithm can not only solve the modeling problem in the case of small spectral discrimination effectively, but also the accuracy of the model is related to the number of spectra and the purity range of product.

In the actual working process of the simulated moving bed, due to the influence of factors such as the feed concentration and temperature change and the inconsistent packing of the chromatographic column, the separation performance under the operation of the initial process parameters may be reduced. The paper first analyzed the mechanism model of the simulated moving bed. Then based on the equilibrium theory of chromatographic separation, a new process parameters point is obtained by using the orthogonal collocation on finite elements method. Finally, taking the separation of fructose syrup as the object, the optimized process parameters under disturbed operation were obtained by the proposed method. The results show that the pass rate of fructose purity increased from 81% to 99%, which proved that the method has good robustness.

Heat exchange network optimization is a research difficulty in the field of chemical process system. Its mathematical model is highly nonconvex and nonlinear, so it often has limitations when using a single heuristic algorithm. The objective of the research is to minimize the annual cost of heat exchange network. In order to solve the problem of individual independent evolution and lack of communication between individuals when random walk algorithm compulsive evolution (RWCE) is used to optimize heat exchanger network, a hybrid algorithm with genetic algorithm (GA) and RWCE is proposed. The mixed algorithm maintains the individual evolution of the individuals in the first half of the dominant population, and replaces the inferior population by generating offspring through periodic crossover and mutation operations, thereby enhancing the original algorithm's ability to optimize integer variables. It makes up for the lack of renewal of vulnerable individuals. In order to improve the computational efficiency when optimizing heat exchanger network with splits under large population and save cost of time, the parallel design of the hybrid algorithm is realized by OpenMP system. The parallel hybrid algorithm is verified by three heat exchange network problems of different scales. The results show that the algorithm can greatly shorten the calculation time compared with the serial algorithm on the premise of effectively improving the optimization quality, and two of the examples have broken through the current optimal solution in the literature.

With the rapid development of process industry and the increasing complexity of process, heat exchangers which serve as the core equipment suffer from the difficulty of the fault early warning. This paper presents a novel method for the fault early warning of tubular heat exchangers. The monitoring indexes are constructed and selected considering the easily measured parameters including temperature, pressure and flow rate of the process fluid. The monitoring indexes are applied to represent the heat transfer and flow resistance performance of the heat exchangers. The EMA algorithm is introduced to process the data and extract the dynamic features of the indexes. A three-dimensional memory matrix is built to represent the working condition of the heat exchangers based on the theory of multiple state estimation (MSET), which avoids the influence of varying condition on the monitoring indexes. Then, the operating observation is applied to calculate the real-time deviation, which achieves the state assessment and fault early warning of the heat exchangers. The abnormal parameters are identified by calculating the real-time deviation contribution rate of each index to achieve accurate fault location.The experimental results show that the method can realize the early warning of leakage faults when the leakage volume accounts for more than 1% of the process fluid flow rate and the early warning of scaling faults when the thickness of the scale layer accounts for more than 2.2% of the pipe diameter.

Aiming at the problem of low early fault detection rate in the nonlinear dynamic process of kernel independent component analysis (KICA), a fault detection and diagnosis approach based on weighted statistical feature KICA (WSFKICA) is proposed. First, the independent component data and residual data are captured from the original data by using KICA. Then, the improved statistical feature data set is obtained by weighted statistical feature and sliding window, and the statistics is constructed from the data set for fault detection. Finally, the method based on contribution chart of monitored variables is used for process fault diagnosis. Compared with traditional KICA statistics, the statistics of the proposed approach has higher fault detection performance for incipient faults in nonlinear dynamic processes. The proposed approach is tested in a simulated case and in the Tennessee-Eastman (TE) process. The simulation results show that the proposed approach has an advantage over ICA, KICA, KPCA and statistical local kernel principal component analysis (SLKPCA).

Aiming at the problems of multiple assumptions about the mechanism modeling of methanol-to-aromatics, complex product prediction process, and high computational cost, a data-driven modeling method based on multiple nonlinear regression analysis was proposed. The influence of reaction pressure, methanol volume space velocity, central temperature, running time, effects of cumulative methanol feed and its interaction on aromatic products is studied in the two-stage fixed bed reaction system. The least square method is used to estimate the parameters and four regression models of quadratic nonlinear product distribution are established. The test results show that the overall decisive indicator of the test sample is 0.9576 and the mean square error MSE is 0.0037, which shows the high prediction accuracy of the product, time saving and strong generalization compared with the traditional kinetic model; The interaction between air speed and pressure influences the hydrocarbon selectivity significantly, and the pressure peak corresponding to the maximum hydrocarbon proportion in the product also increases with the airspeed increases.

Under the background of double carbon, using biomass based aviation fuel to replace traditional aviation fuel has become one of the current research hotspots. The composition of biomass based aviation oil is different from that of traditional aviation oil. The naphthenic hydrocarbons of biomass based aviation oil are obtained by lignin hydrodeoxygenation, which is different from that of traditional aviation oil in structure. The combustion characteristics of cycloalkanes with different structures are very different. Based on this, this paper studied the low-temperature combustion characteristics of four typical biomass based cycloalkanes (cyclopentane, cyclohexane, ethyl cyclohexane and decahydronaphthalene) mixed with RP-3 aviation oil and its influence on the combustion process in compression ignition engine through variable compression ratio internal combustion engine, so as to study the feasibility of fuel singleness. The results show that increasing the mixing ratio, decahydronaphthalene can obviously promote the combustion effect, the ignition point is in advance, the exothermic peak value is increased, and the exothermic is more concentrated; ethyl cyclohexane has similar combustion characteristics to aviation oil, while cyclohexane and cyclopentane will delay the combustion phase, reduce the heat release rate, increase the easy compression ignition difficulty of mixed fuel and is not conducive to combustion. The results of this paper have important guiding significance for the catalytic hydrogenation of lignin to produce cycloalkanes and biomass-based cycloalkanes.

A concentration flow cell can convert salinity gradient energy SGE into electricity by the reversable faradaic reactions between faradaic electrodes and two salt solutions with different concentration. Compared with traditional SGE-extraction technologies that rely on selective membranes, concentration flow cells have advantages of low cost, long lifetime and small volume, etc. However, the electrodes materials reported previously need to be pre-charged by external power sources and may release toxic matters (for example, hexacyanoferrate). Herein, environmentally friendly ammonium vanadium bronze is proposed as electrodes of concentration flow cells without pre-charge treatment yielding superhigh SGE-extraction performance. The average power density of 194.3 mW·m^-2 increased by 37% comparing with graphene hydrogel based SGE-extraction devices (141.4 mW·m^-2) for 20 and 500 mmol·L^-1 NaCl solutions. Moreover, the effect of ion size was also investigated. This work paves a way for designing functional electrode materials of concentration flow cells for harvesting SGE.

To study the interaction between functional groups during slow pyrolysis of coal, Naomaohu coal (NMHcoal) sample was pyrolyzed in a drop tube furnace reactor with a short residence time to prepare rapid pyrolysis char (NRPchar) with part remained reactivity of coal but most of the low-temperature crosslinking site precursor eliminated. TG results indicated that the pyrolysis of NMHcoal/NRPchar with a ratio of 5∶5 at 500℃ shows a strong negative synergy. The fixed bed pyrolysis results show that some volatiles generated by the pyrolysis of NMHcoal diffused into the NRPchar, which provided more probability and time to the combination of ?CH₃ with aromatic carbon radicals and ?O. As a result, the structure of naphthalenes and phenols containing methyl groups in tar, and also the alkylated oxyaromatic carbon structure and ether structure in the char increased. The increased release of phenols reduced the oxyaromatic carbon structure in the char. More polycyclic aromatic hydrocarbon precursors are generated in NRPchar, they react with phenolic substances to generate polycyclic aromatic hydrocarbons and CO, which increase the content of 5 and 6 ring compounds in the co-pyrolysis tar, while the other part is retained in the semi-coke to reduce its specific surface area.

The release of four main gaseous nitrogen products (HCN, NH₃, NO and NO₂) from bituminous coal and anthracite with different particle sizes during pyrolysis, gasification and combustion were studied by using a micro fluidized bed reactor combined with a rapid process mass spectrometer at 850—940℃. The results show that the micro fluidized bed can detect the dynamic release sequence and type of volatile-N and char-N in real time. The change of pyrolysis, gasification and combustion reaction atmosphere mainly affects the release of HCN and NH₃. The gaseous nitrogen of pyrolysis is mainly produced from volatiles. The released amount of HCN and NH₃ in combustion is affected by temperature, while the released amount of gaseous nitrogen products in gasification changes little with temperature. The changes in coal particle size and temperature have complex effects on various gaseous releases in bituminous coal and anthracite. Among them, the release characteristics of NH₃ are important characteristics that distinguish the release of volatile N and semi-coke.

The artificial photosynthesis system can use solar energy to convert carbon dioxide into high value-added chemical products, which can effectively solve the energy and environmental problems faced by mankind, and has great development prospects. However, artificial photosynthesis systems face major challenges such as poor product selectivity, high overpotential, and low solar energy utilization. Here we present a hybrid microbial-photoelectrochemical system comprised of a monolithic photoanode, which is assembled by attaching a silicon cell at the reverse side of a TiO₂ nanorod array for water oxidation, and a biocathode that is capable of reducing CO₂ to CH₄. The hybrid system shows an excellent CH₄ production rate of (10.7±0.2) L·d^-1·m^-2, around 13 times higher than that of previous studies, and achieved a highly selective CO₂ reduction to CH₄ with a Faradaic efficiency up to 98.5%±2.1%. This work proposes an effective approach for the generation of valuable products using artificial photosynthesis.

Water-soluble polymers such as poly-vinylpyrrolidone (PVP), poly-vinylcaprolactam (PVCap), and Gaffix VC-713 are predominantly used as kinetic hydrate inhibitors (KHIs) in the natural gas industry to control the formation of hydrates. However, their industrial application was limited because of low biodegradability. Therefore, developing environment-friendly, biodegradable inhibitors is necessary. In this paper, readily biodegradable sodium alginate and the monomer of PVCap were copolymerized to synthesize NaAlg-g-PVCap, a new hydrate kinetic inhibitor. Its hydrate inhibition performances was investigated through the maximum subcooling and gas consumption, as well as the biodegradability evaluated through the value of BOD₅/COD. The results showed that the maximum subcooling of NaAlg-g-PVCap system at low concentration (0.25%(mass)) was better than PVP K90, but lower than PVCap, and its value decreased slightly with the increased concentration. Below the maximum subcooling (ΔT_sub=5℃), NaAlg-g-PVCap showed both nucleation and growth inhibition effects. The initial growth rate of hydrate of NaAlg-g-PVCap system was only about 1/10 of the pure water system, also much higher than PVP systems. Meanwhile, the addition of NaAlg-g-PVCap reduced the gas consumption of the system over 60% compared with that of pure water/PVP system, close to PVCap system. However, the nucleation inhibition effect of NaAlg-g-PVCap decreased significantly with the increase of subcooling, which may be the result of the interaction of two segments in the copolymer. The biodegradability of NaAlg-g-PVCap was 26% higher than that of PVCap, tended to be easily degraded. It shows that the copolymerization of PVCap and NaAlg optimizes the overall performance, showing better hydrate inhibition performance and biodegradability.

Anaerobic digestion (AD) coupled with hydrothermal carbonization (HTC) technology has significant advantages and significance for sustainable resource utilization of garden waste. In this work, the grass was pretreated with AD for 7—28 d. The effects of AD coupled with HTC on the characteristics of hydrochar and its pyrolysis and product release properties were investigated deeply. AD pretreatment promoted mainly the decarboxylation reaction in the HTC process. Besides, the functional properties of hydrochar were regulated effectively by changing the lignocellulose composition ratio and biomass structural characteristics. Noticeably, the dense rigid structure inside the biomass was broken by AD pretreatment, which promoted the formation of rich pores and the increase of the specific surface area of the hydrochar. The best performance of hydrochar was achieved at 17.52% biodegradability (AD 7 d), with mass yield, high heating value (HHV), energy yield and energy density reaching 62.75%, 23.81 MJ·kg^-1, 80.31% and 1.28%, respectively. In addition, TG-MS analysis results revealed that AD pretreatment improves the thermal stability of carbon and the generation of energy gas in pyrolysis products, which is helpful for the upgrading and utilization of pyrolysis gas.

In this study, the mechanism of co-pyrolysis of the coal-like model compound 1-naphthyl methanol and isotope tracer was studied at 500℃. The pyrolysis process is carried out by using a thermal cracker, and then mass spectrometry is used to detect the product to infer the reaction and change behavior of free radicals. The results show that the free radical reaction dominates the pyrolysis process at 500℃, and this behavior is more pronounced. Through the isotope labeling method and spin trapping technology, the hydrogen radicals were successfully captured. The transformation process of the conversion of 1-naphthyl methanol to 1-naphthaldehyde is revealed, and it is found that the substituents on the benzene ring play an important role in the thermal process of 1-naphthyl methanol. At the same time, qualitative and semi-quantitative analysis of free radicals and products was carried out, and it was found that the abundance of products after the addition of free radical traps was an order of magnitude lower than before, indicating that the free radical traps inhibited the formation of products.

Microwave digestion and hydride generation-atomic fluorescence spectrometry were used to investigate the migration and transformation of selenium (Se) in nine ultra-low emission units in service. The characteristics of fly ash from circulating fluidized bed (CFB) and pulverized coal (PC) units are compared for understanding the Se adsorption ability in fly ash. After combustion, Se in coal is essentially volatilized in gas but only a small amount is remained in bottom slag. Compared to concentration normalization method and mass distribution method, relative enrichment factor method is more suitable to evaluate the Se enrichment ability for feed coal and combustion by-products, which indicates that Se is enriched in fly ash from both CFB and PC units. Low combustion temperature and CaO additive in CFB boiler can not only reduce Se release ratio from coal but also enhance the Se adsorption ability in fly ash. As a result, Se enrichment in bottom slag and fly ash from CFB is more than that from PC, while Se in gypsum from CFB unit is less than that of PC. Moreover, Se adsorption content is heavily depended on the physical properties of fly ash. The amount of selenium adsorbed by fly ash increases with the increase of specific surface area or pore volume, but decreases with the increase of particle size or pore size. The fly ash from CFB unit has high unburned carbon content, irregular shape, rough surface and more honeycomb pores, which makes Se enriched in fly ash from CFB more than that of PC.

Ultra-high molecular weight polyethylene (UHMWPE) is a commonly used high-properties polymer. Due to the influence of high viscosity, its processing and application are greatly restricted. The uniformity of the additive dispersion during processing is considered to be the key for the preparation of high-properties UHMWPE composites. Polyethylene glycol (PEG) has high fluidity and is widely used to improve the viscosity behavior of UHMWPE. But the dispersion effect of the added phase in the composite material has an important influence on the performance of the UHMWPE composites. UHMWPE/PEG composites with different proportions were prepared by dry powder mixing, solution mixing, and melt extrusion blending. Based on the melt tensile test, the influence of blending mode and ratio on the entanglement behavior and properties of UHMWPE was studied, and the microscopic mechanism of the disentanglement of UHMWPE molecular chain was analyzed by the presence of PEG. The results show that the addition of PEG increases the plasticity of UHMWPE, reduces its internal chain entanglement density, and increases the mobility between molecular chains. Although the crystallinity of the material is improved to certain extent, it does not significantly change the melting temperature. Among the three mixing methods, when 5% PEG is added, the untangling effect of dry powder mixing and extrusion mixing is more obvious, and the chain entanglement density is reduced by about 26%.

With the rapid development of industry, increasing attention has been paid to the efficient separation of organic solvents by nanofiltration membranes. However, nanofiltration membranes are difficult to be further industrialized because of the trade-off effect between flux and selectivity. In this paper, hydrophobic g-C₃N₄ nanosheets and hydrophilic amylose (AM) were used as building units to prepare heterostructure g-C₃N₄@AM lamellar membrane by double needle electrostatic atomization. The hydrophilic amylose promotes the dissolution of polar solvents and the hydrophobic g-C₃N₄ nanosheets provide the low resistance diffusion of polar solvents. Therefore, this heterostructure structure greatly enhances the permeation of the membrane to polar solvents without reducing the separation ability. Compared with g-C₃N₄ membrane, the g-C₃N₄@AM membranes show 1—2 times higher polar solvent permeance. Simultaneously, the g-C₃N₄@AM membranes accomplish 99% rejections towards dye molecules with sizes above 1.5 nm. After long-term operation, pressure cycle and acid-base stability test, the variation of solvent permeance and dye rejection is below 6%, which demonstrate that this hydrophilic/hydrophobic heterostructured lamellar membrane shows great operating stability.

Two-dimensional transition metal carbides and carbonitrides (MXenes) are the latest additions of the 2D world, which can be obtained by selective etching the a atomic layers from layered MAX precursors. In the traditional method of preparing MXene, the commonly used etchant is hydrofluoric acid. However, the use of concentrated hydrofluoric acid may inevitably bring about safety problems and even the destruction of crystal structure, resulting in the deterioration of intrinsic physical and chemical properties. This article starts from the typical carbide precursor Ti₃AlC₂ and uses NH₄BF₄ as an etchant to effectively reduce the amount of acid used in the system. More importantly, during the reaction process, the A layers were etched accompanied by intercalation of \mathrm{N}{\mathrm{H}}_{\mathrm{4}}^{+}, by which the interlayer spacing was expanded and interlayer interaction was greatly weakened. High exfoliation efficiency of 2D Ti₃C₂ with intact crystallinities exfoliation was realized by a sequent hand shaking process. The electrochemical performance of as-obtained Ti₃C₂ was further characterized, showing an excellent capacitive electrochemical performance (503 F?g^-1 at a scan rate of 5 mV?s^-1) and cycling stability (the capacitance retention rate is 95.8% at 5 A·g^-1 after 10⁴ cycles). This provides new ideas for the synthesis and application of Ti₃C₂ nanosheets.

A small-scale experimental device of jet fire in a pit was built, and experimental simulation was conducted to study the flame characteristics of horizontal propane jet fire caused by the leakage of pipeline buried underground. The flame is restricted by the side wall of the pit, first hits the tunnel and then develops upward along the side wall to form a vertical flame. The experimental results show that the flame length first increases and then decreases as the leakage mass flow rate increases, while the flame width continuously increases. In addition, vortex pairs, indicated by a pair of counter-rotating flames, were observed to appear on both lateral sides of the flame under critical conditions. In order to explore the formation mechanism of vortex pairs, the instability of flame flow field is further studied by numerical simulation.