CuCe/Ti-A and CuCe/Ti-R catalysts were prepared using anatase TiO₂ (TiO₂-A) and rutile TiO₂ (TiO₂-R) as supports using the incipient wetness impregnation method for the carbon monoxide (CO) oxidation reaction and were compared with a CuCe-C catalyst prepared using the co-precipitation method. The CuCe/Ti-A catalyst exhibited the highest activity, with complete CO conversion at 90 ℃, when the gas hourly space velocity was 24000 ml·g^-1·h^-1 and the CO concentration was approximately 1% (vol). A series of characterizations of the catalysts revealed that the CuCe/Ti-A catalyst has a larger specific surface area, more Cu⁺ species and oxygen vacancies, and the Cu species of CuCe/Ti-A catalyst is more readily reduced. In situ FT-IR results indicate that the bicarbonate species generated on the CuCe/Ti-A catalyst have lower thermal stability than the carbonate species on CuCe/Ti-R, and will decompose more readily to form CO₂. Therefore, CuCe/Ti-A has excellent catalytic activity for CO oxidation.

The Ca(OH)₂/CaO thermochemical energy storage (TCES) system based on calcium looping has received extensive attention owing to its high energy storage density, prolonged energy storage time, and environmental friendliness. The heat storage process of the Ca(OH)₂/CaO TCES system in a mixed heating reactor was evaluated in this study, by employing a combination of direct and indirect heating modes. The dehydration process was studied experimentally, and a numerical model was established and verified based on the experimental results. The dehydration behavior of 500 g of Ca(OH)₂ powder was investigated in a fixed-bed reactor with mixed heating. The experimental and simulation results indicated that mixed heating causes combined centripetal and horizontal propulsion. Heat input is the main limiting factor in the heat storage process, because the radial advance of the reaction is hindered by the low thermal conductivity of the solid reactant particles. Heat transmission partitions were added to enhance the performance of the reactor. The performance of the modified reactor was compared with that of a conventional reactor. The radial heat transmission partitions in the modified reactor effectively enhance the energy storage rate and reduce the reaction time by 59.5% compared with the reactor without partitions.

Important efforts have been made over the past years to improve the drug acts, which leads to the discovery of novel drug preparations and delivery systems. The optimal design of such processes requires a molecular-level understanding of the interactions between drug molecules and biological membranes. The thermodynamic investigation provides deep and complete knowledge of interactions and the choice of appropriate and suitable production compounds in pharmaceutical fields. Particularly, the analysis of drugs + co-solvents in aqueous media is the central issue in many types of research because they exert their impact by interacting with biological membranes. This work is aimed to measure the density and speed of sound for the thiamine hydrochloride in water + deep eutectic solvents (DESs) mixtures (choline chloride/urea, choline chloride/ethylene glycol and choline chloride/glycerol) at temperature range (293.15–308.15) K. By correlation of the evaluated parameters in some standard relations, the partial molar parameters i.e. apparent molar volumes, V_φ,m, and apparent molar isentropic compression, k_s,φ,m, are calculated. In addition, apparent molar isobaric expansion, E_φ,m⁰, and Hepler’s constant are computed from the density and speed of sound data. For fitting the experimental V_φ,m and k_s,φ,m the Redlich-Meyer equation was employed that the important quantities; standard partial molar volume, V_m⁰, and partial molar isentropic compression, k_s,m⁰, were obtained. The thermodynamic analysis of the studied system also plays a crucial role in the pharmaceutical industry.

Electrolytic manganese residue (EMR) can cause serious environmental and biological hazards. In order to solve the problem, zeolite A (EMRZA) and zeolite X (EMRZX) were synthesized by EMR. The pure phase zeolites were synthesized by alkaline melting and hydrothermal two-step process, which had high crystallinity and excellent crystal control. And the optimum conditions for synthesis of zeolite were investigated: NaOH-EMR mass ratio = 1.2, L/S = 10, hydrothermal temperature = 90 ℃, and hydrothermal time = 6 h. Then, EMRZA and EMRZX showed excellent adsorption of Cd²⁺. When T = 25 ℃, time = 120 min, pH = 6, C₀ = 518 mg·L^-1, and quantity of absorbent = 1.5 g·L^-1, the adsorption capacities of EMRZA and EMRZX reached 314.2 and 289.5 mg·g^-1, respectively. In addition, after three repeated adsorption–desorption cycles, EMRZA and EMRZX retained 80% and 74% of the initial zeolites removal rates, respectively. Moreover, adsorption results followed quasi-second-order kinetics and monolayer adsorption, which was regulated by a combination of chemisorption and intra-particle diffusion mechanisms. The adsorption mechanism was ions exchange between Cd²⁺ and Na⁺. In summary, it has been confirmed that EMRZA and EMRZX can be reused as highly efficient adsorbents to treat Cd²⁺-contaminated wastewater.

The liquid phase selective hydrogenation of cinnamaldehyde has been investigated over the catalysts Co-C-T (T = 400–700 ℃), which were derived from the carbonization of the MOF precursor Co-BTC at different temperatures in inert atmosphere. Co-C-500 exhibited a higher conversion (85.3%) than those carbonized at other temperatures, with 51.5% selectivity to cinnamyl alcohol, under a mild condition (90 ℃, 4 h, 2 MPa H₂, solvent: 9 ml ethanol and 1 ml water). The high catalytic activity of Co-C-500 can be ascribed to the large specific surface area of the catalyst, the uniformly dispersed metallic cobalt nanoparticles, and the more defect sites on the carbon support. Moreover, Co-C-500 showed excellent reusability in 5 successive cycles, mainly related to the uniformly dispersed cobalt nanoparticles embedded in carbon support.

Nonequilibrium stage model is a significant improvement in multicomponent separation process simulation, but more equations are involved and the solution of the model equations, which relies on an adequate initial guess for convergence of the Newton method, is difficult. In this work, based on the concept of pseudo-transient continuation approach, we proposed a new pseudo-transient (PT) nonequilibrium method. The proposed method decouples the strongly coupled model equations by introducing dynamic equations for material and energy conservation, as well as transition equations. Thus, the steady-state solution of the nonequilibrium stage model can be obtained through a robust and fast integration process, and the initial guess issue in Newton method can be effectively avoided. Two simulation cases were used to demonstrate the advantages and applicability of the proposed PT nonequilibrium method.

Presently, ammonia is an ideal candidate for future clean energy. The Haber-Bosch process has been an essential ammonia production process, and it is one of the most important technological advancements since its invention, sustaining the explosive growth of military munitions industry and fertilizers in the first half of the 20th century. However, the process is facing great challenges: the growing need for ammonia and the demands of environmental protection. High energy consumption and high CO₂ emissions greatly limit the application of the Haber-Bosch method, and increasing research efforts are devoted to “green” ammonia synthesis. Thermocatalytic, electrocatalytic, and photocatalytic ammonia production under mild conditions and the derived chemical looping and plasma ammonia production methods, have been widely developed. Electrocatalytic and photocatalytic methods, which use low fossil fuels, are naturally being considered as future directions for the development of ammonia production. Although their catalytic efficiency of ammonia generation is not yet sufficient to satisfy the actual demands, considerable progress has been made in terms of regulating structure and morphology of catalyst and improving preparation efficiency. The chemical looping approach of ammonia production differs from the thermocatalytic, electrocatalytic, and photocatalytic methods, and is the method of reusing raw materials. The plasma treatment approach alters the overall ammonia production approach and builds up a new avenue of development in combination with thermal, photocatalytic, and electrocatalytic methods as well. This review discusses several recent effective catalysts for different ammonia production methods and explores mechanisms as well as efficiency of these catalysts for catalytic N₂ fixation of ammonia.

The effects of substrate mingling ratio (SMR) (1:1, 1:2, 1:3, 3:1, and 2:1) and organic loading rate (OLR) (50–90 g total solids per liter per day) on anaerobic co-digestion performance and microbial characteristics were investigated for pig manure (PM) and pretreated/untreated corn stover in batch and semi-continuous anaerobic digestion (AD) system. The results showed that SMR and pretreatment affected co-digestion performance. The maximum cumulative methane yield of 428.5 ml·g^-1 (based on volatile solids (VS)) was obtained for PC_P13, which was 35.7% and 40.0% higher than that of CS_U and PM. In the first 5 days, the maximum methane yield improvement rate was 378.1% for PC_P13. The daily methane yield per gram VS of PC_P13 was 11.4%–18.5% higher than that of PC_U13. Clostridium_sensu_stricto_1, DMER64, and Bacteroides and Methanosaeta, Methanobacterium, and Methanospirillum had higher relative abundance at the genus level. Therefore, SMR and OLR are important factor affecting the AD process, and OLR can affect methane production through volatile fatty acids.

At present, the environment impact of refrigerants has been given attention. The binary mixture R152a/R1234ze(E) is an environmentally friendly refrigerant, which solves problems of poor cooling performance of the R1234ze(E) cycle and flammability of R152a. In order to obtain its basic thermal and physical parameters, it is necessary to carry out vapor–liquid equilibrium (VLE) research, and the cubic equation of states (EOS) is often used in the calculation of the thermodynamic properties of mixtures. In this paper, the VLE predicted models for R152a/R1234ze(E) in the temperature range of 298.15–328.15 K were constructed using Soave-Redlich-Kwong (SRK), Peng-Robinson (PR) equations of state (EOS) combined with van der Waals (vdW), Huron-Vidal (HV) mixing rules, respectively. The equilibrium pressures and vapor-phase mole fractions of the models were obtained by calculation, and all four models presented an extreme correlation with the experimental data. And it can be concluded that the calculated results of the PR + HV model are closer to the experimental data than those of the other three models, with the average absolute deviation of 0.0027 for vapor-phase mole fraction (AAD(y_cal)) and the average absolute relative deviation of 0.243% for equilibrium pressure (AARD(p_cal)), which provides a basis for accurately calculating the thermophysical properties of the mixture R152a/R1234ze (E).

Instead of the energy-intensive Haber-Bosch process, the researchers proposed a way to produce ammonia using water and nitrogen as feedstock, powered by electricity, without polluting the environment. Nevertheless, how to design efficient electrocatalyst for electrocatalytic nitrogen reduction reaction (NRR) is still urgent and challenging. Herein, a strategy is proposed to adjust the morphology and surface electronic structure of electrocatalyst by optimizing material synthesis method. LiNbO₃ (lithium niobate, LN) cubes with oxygen-rich vacancy and regular morphology were synthesized by hydrothermal synthesis and followed molten salt calcination process, which were used for electrocatalytic NRR under mild conditions. Compared with LN nanoparticles synthesized by solid phase reaction, LN cubes exhibit better NRR performance, with the highest ammonia yield rate (13.74 μg·h^-1·mg^-1) at the best potential of -0.45 V (vs. reversible hydrogen electrode, RHE) and the best Faradaic efficiency (85.43%) at -0.4 V. Moreover, LN cubes electrocatalyst also demonstrates high stability in 7 cycles and 18 h current–time tests. Further investigation of the reaction mechanism confirmed that the structure of oxygen vacancy could adjust the electronic structure of the electrocatalyst, which was conducive to the adsorption and activation of N₂ molecule and also increased the ECSA of electrocatalyst, thus providing more active sites for the NRR process.

The slag composition corresponding to different coals varies significantly, which directly affects the operation of industrial entrained-flow gasifier and the service life of refractory bricks. In this study, the corrosion resistance of several typical coal slags for gasification on high chromia refractory bricks was comparatively investigated by static laboratory crucible tests and thermodynamic simulations. The results demonstrated that the corrosion degree of high chromia refractory bricks by different coal slags was high-Ca/Na slag > high-Fe slag > high-Si/Al slag. The surface structure of the refractory was relatively flat after corrosion by high-Si/Al slag, and the primary corrosion reaction was the partial dissolution of the matrix by the slag. High-Fe slag was prone to the precipitation of iron phases as well as the formation of (Mg, Fe) (Al, Cr)₂O₄ composite spinel layer at the slag/refractory interface. The high-Ca/Na slag was susceptible to react with the refractory to yield a low melting point phase, which led to the destruction of the matrix structure of the refractory and an isolated distribution of particles. In addition, the monoclinic ZrO₂ in the refractory reacted with CaO in the slag to formed calcium zirconate, which loosened its phase toughening effect, was the primary factor that aggravated the refractory corrosion.

Release of vanadium(V) from industry has threatened the environment and human health. In this paper, a removal method of vanadium(V) is proposed using a by-product of the yellow phosphorus industry (phosphorus-iron) as a reducing agent. The thermodynamics analysis shows that the Gibbs free energy is always negative from 0 to 100 ℃, indicating a spontaneous process. Effect of the phosphorus-iron slag/sulfuric acid dosage and temperature on the removal efficiency is comprehensively studied, and the kinetics parameters are calculated based on a quasi-first order reaction kinetics model. Results indicate that vanadium(V) can be entirely reduced by using phosphorus-iron slag, the frequency factor and apparent activation energy are 3.23×10⁹ min^-1 and 64.50 kJ·mol^-1 for vanadium(V) reduction. Based on above results, a lab-scale reactor is constructed and achieves a removal efficiency of ~100% and a treatment capacity of 200 ml vanadium(V) solution (2 g·L^–1) within 3 h. This work demonstrates the feasibility of vanadium(V) reduction using phosphorus-iron slag as a reducing agent in applications.

A novel light responsive nanosphere was constructed, and it was used as a drug carrier to investigate the loading and release properties of the Quercetin (QU). In this paper, mesoporous silica nanoparticles (MSN) were used as a substrate, and 3-aminopropyl triethyoxysilane was used as a surface modification agent to introduce —NH₂, and the azobenzene-4,4'-dicarboxylic acid (AZO) was used as light responsive agent to introduce the group of —N = N—, and then β-cyclodextrin (β-CD) was combined with AZO through host–guest interaction to construct light responsive nanoparticles (MSN@β-CD). The structure and properties of the carrier were analyzed by FTIR, BET, XPS, TGA, XRD, SEM and TEM. In vitro drug release studies showed the release rate of QU@MSN@β-CD (dark) was 12.19% within 72 h, but the release rate of QU@MSN@β-CD (light 10 min) was 26.09%, exhibiting a light-responsive property. The CCK8 tests demonstrated that MSN@β-CD could significantly decrease the toxicity of QU. Therefore, the controllable light-responsive drug delivery system has great application prospects.

Air nanobubbles (A-NBs) were used to inhibit the brass corrosion in circulating cooling water for the first time in the study. The results of mass loss method and electrochemical method showed that A-NBs had the obvious corrosion inhibition effect. The inhibition rate reached 52% at 35 ℃. The impedance and surface characterization results of corrosion samples indicated that the corrosion inhibition mechanisms of A-NBs mainly included adsorption of corrosion ions, promoting the formation of the passivation film on metal surface and the formation of the bubble layer and scale film on metal surface. A-NBs are potential excellent corrosion inhibitors.

We described a novel polymer-lipase conjugate for high-efficient esterification of vitamin E using vitamin E and succinic anhydride as the substrates in nonaqueous media. In this work, the monomer, N-isopropylacrylamide (NIPAM), was grafted onto Candida rugosa lipase (CRL) to synthesize poly(NIPAM) (pNIPAM)-CRL conjugate by atom transfer radical polymerization via the initiator coupled on the surface of CRL. The result showed that the catalytic efficiencies of pNIPAM-CRL conjugates (19.5–30.3 L·s^-1·mmol^-1) were at least 7 times higher than that of free CRL (2.36 L·s^-1·mmol^-1) in DMSO. It was attributed to a significant increase in K_cat of the conjugates in nonaqueous media. The synthesis catalyzed by pNIPAM-CRL conjugates was influenced by the length and density of the grafted polymer, water content, solvent polarity and molar ratio of the substrates. In the optimal synthesis, the reaction time was shortened at least 7 times, and yields of vitamin E succinate by pNIPAM-g-CRL and free CRL were obtained to be 75.4% and 6.6% at 55 ℃ after the reaction for 1.5 h. The result argued that conjugation with pNIPAM induced conformational change of the lid on CRL based on hydrophobic interaction, thus providing a higher possibility of catalysis-favorable conformation on CRL in nonaqueous media. Moreover, pNIPAM conjugation improved the thermal stability of CRL greatly, and the stability improved further with an increase of chain length of pNIPAM. At the optimal reaction conditions (55 ℃ and 1.5 h), pNIPAM-g-CRL also exhibited good reusability in the enzymatic synthesis of vitamin E succinate and kept ~70% of its catalytic activity after ten consecutive cycles. The research demonstrated that pNIPAM-g-CRL was a more competitive biocatalyst in the enzymatic synthesis of vitamin E succinate and exhibited good application potential under harsh industrial conditions.

The wall wettability of microchannels plays an important role in the gas–liquid mass transfer dynamics under Taylor flow. In this study, we regulated the contact angle of the wall surface through surface chemical grafting polymerization under controlled experimental conditions. The dynamic changes of CO₂ bubbles flowing along the microchannel were captured by a high-speed video camera mounted on a stereo microscope, whilst a unit cell model was employed to theoretically investigate the gas–liquid mass transfer dynamics. We quantitatively characterized the effects of wall wettability, specifically the contact angle, on the formation mechanism of gas bubbles and mass transfer process experimentally. The results revealed that the gas bubble velocity, the overall volumetric liquid phase mass transfer coefficients (k_La), and the specific interfacial area (a) all increased with the increase of the contact angle. Conversely, gas bubble length and leakage flow decreased. Furthermore, we proposed a new modified model to predict the gas–liquid two-phase mass transfer performance, based on van Baten's and Yao's models. Our proposed model was observed to agree reasonably well with experimental observations.

The adverse effects of eutrophication have prompted the use of various remediation techniques for phosphate (PO₄^3–) removal owing to it being the major causative agent. Herein, the influence of different solvents and ratios of 2-aminoterepthalic acid on the efficiency of magnetic biomass metal–organic framework composites based on the in situ growth of NH₂-MIL-101 (Fe) onto magnetized peanut husks towards PO₄^3– removal was assessed via the adsorption technique. The magnetic biocomposite labelled as MPN@NH₂-MIL-101 (Fe) exhibited the best efficiency owing to its mesoporous structures and presence of abundant oxygen and nitrogen possessing functional groups. Adsorption results confirmed MPN@NH₂-MIL-101 (Fe) to have a high adsorption capacity of (14.0 ±0.3) mg·L^-1 at a PO₄^3- concentration of 20 mg·L^-1 with an associated high stability within pH 2–10. The adsorption kinetics for the process was well described by both Elovich and pseudo-second-order kinetic models and was mediated by both internal diffusion and liquid film diffusion. The Temkin and Freundlich models fitted the equilibrium data well signifying occurrence of both physical and chemical adsorption on a heterogeneous surface. It is concluded that MPN@NH₂-MIL-101 (Fe) is a promising adsorbent for the effective removal of phosphate from a water body.

The transformation of CO₂ into high value-added product is a promising pathway for utilizing CO₂. However, the process tends to require harsh reaction conditions owing to CO₂ chemical inertness. Designing a high efficiency catalytic system with environmentally benign characteristic are important determinants. In this work, protic ionic liquids [TMG][2-OPy] were prepared via one-step neutralization between 1,1,3,3-tetramethylguanidine and 2-hydroxypyridine, applying to the domain of synthesizing quinzoline-2,4(1H,3H)-diones from CO₂ and 2-aminobenzontiles without any solvent or metal, achieving the yield of 97% at 90 ℃ for 8 h under atmospheric. A series of substrates with good to acceptable yield were detected, revealing the generality and universality of the catalyst. Furthermore, the system could be facilely reused for at least six runs, retaining the yield of 94%. A preliminary kinetic equation is calculated with the activation energy of 68 kJ·mol^-1, and a plausible reaction mechanism was put forward. This study highlights that the [TMG][2-OPy] enables to activate CO₂ carboxylation efficiently.

The effective utilization of natural gas resources is a promising option for the implementation of the “dual carbon” strategy. However, the capture of carbon dioxide with relatively lower concentration after the combustion of natural gas is the crucial step. Fortunately, the lattice oxygen is used for chemical cycle conversion of methane to overcome the shortcomings mentioned above. A method was proposed to synthesize perovskite for methane cycle conversion using metal organic framework as a precursor. Morphology and pore structure of Fe₂O₃-LaFeO₃ composite oxides were regulated by precursor synthesis conditions and calcination process. Moreover, the chemical looping conversion performance of methane was evaluated. The results showed that the pure phase precursor of La[Fe(CN)₆]·5H₂O was synthesized with the specific surface area of 23.91 m²·g^-1 under the crystallization of 10 h and the pH value of 10.5. Fe₂O₃-LaFeO₃ was obtained by controlled calcination of La[Fe(CN)₆]·5H₂O and Fe₂O₃ with variable mass ratio. The selectivity of CO₂ can reach more than 99% under the optimal parameters of methane chemical looping conversion: m(Fe₂O₃):m(LaFeO₃) = 2:1, the reaction temperature is 900 ℃, the lattice oxygen conversion is less than 40%. Fe₂O₃-LaFeO₃ still has good phase and structure stability after five redox reaction and regeneration cycles.

The development of intensification technology for spouted beds has become a current research focus, and an effective way to improve the efficiency of spouted beds is to reform their structure. Although numerous studies have been conducted on conventional beds, there are few reviews on the comprehensive application of intensification technology for spouted beds. In this paper, we comprehensively review the role of intensification technology in spouted beds for use in hydrodynamics, drying, desulfurization, pyrolysis, coating, biomass and waste gasification, and biomass drying from the perspective of experiment and simulation. Finally, potential problems and challenges in current spouted-bed research are summarized.

The deformation characteristics of the cavity due to droplet impact on a water surface are experimentally investigated. Dimensional analysis shows that the characteristic values of time, depth, and horizontal diameter can be taken as 10^-3 times the ratio of surface tension to the product of viscosity coefficient and gravitational acceleration, the maximum depth, and the maximum horizontal diameter, respectively. The evolutions of the dimensionless cavity sizes for different values of Weber number (We) coincide for 220 < We < 686. A partial-sphere model of cavity is established based on experimental observations. Energy models are then derived, and the energy conversions are calculated to identify the relationship between these conversions and cavity deformation. It is found that the kinetic energy model established under the hypothesis proposed by Leng is no longer applicable when the dimensionless time t^* < 3.5, owing to deviations from the geometric model.

As a key component of injection molding, multi-cavity hot runner (MCHR) system faces the crucial problem of polymer melt filling imbalance among the cavities. The thermal imbalance in the system has been considered as the leading cause. Hence, the solution may rest with the synchronization of those heating processes in MCHR system. This paper proposes a ‘Master-Slave’ generalized predictive synchronization control (MS-GPSC) method with ‘Mr. Slowest’ strategy for preheating stage of MCHR system. The core of the proposed method is choosing the heating process with slowest dynamics as the ‘Master’ to track the setpoint, while the other heating processes are treated as ‘Slaves’ tracking the output of ‘Master’. This proposed method is shown to have the good ability of temperature synchronization. The corresponding analysis is conducted on parameters tuning and stability, simulations and experiments show the strategy is effective.

A set of hydrodynamic similarity laws is applied to the scale-up of ethylene polymerization fluidized bed reactors (FBRs) under the condensed mode operation. The thermal stability of open-loop controlled FBRs is investigated by the homotopy continuation method. And the Hopf bifurcation point is selected as an index of the thermal stability similarity. The simulation results show the similarity in state variables, operation parameters, the space–time yield (STY), and the thermal stability of FBRs with different scales. Furthermore, the thermal stability behaviors and similarity of the closed-loop controlled FBRs with different scales are analyzed. The observed similar trend of Hopf bifurcation curves reveals the similarity in the thermal stability of closed-loop controlled FBRs with different scaling ratios. In general, the results of the thermal stability similarity confirm that the hydrodynamics scaling laws proposed in the work are applicable to the scale-up of FBRs under the condensed mode operation.

As one of the most stable metal-organtic framework (MOF), zeolitic imidazolate framework-8 (ZIF-8) has been widely studied for applications in the field of energy storage, catalysis, and environment protection. In this paper, ZIF-8 was employed to enhance the electrochemical properties and thermal stability of the electrospun poly(vinylidene fluoride-co-hexafluoropropylene)/polyacrylonitrile (PVDF-HFP/PAN) composite separator. The results indicate that the test cells assembled with the composite separators show improved rate capability, high discharge capacity, and stable cycling performances. The addition of ZIF-8 can improve the affinity of PVDF-HFP/PAN toward liquid electrolytes, and further enhance the ionic conductivity of the composite separators. In addition, the thermal stability of the PVDF-HFP/PAN separator has been improved by ZIF-8 nanoparticles. This work can provide insight into the application of MOF materials in Li-ion batteries.

This work aims to systematically study hydrodynamics and mixing characteristics of non-Newtonian fluid (carboxyl methyl cellulose, CMC) in dual shaft eccentric mixer. Fluid rheology was described by the power law rheological model. Computational fluid dynamics was employed to simulate the velocity field and shear rate inside the stirred tank. The influence mechanism of the rotational modes, height difference between impellers, impeller eccentricities, and impeller types on the flow field have been well investigated. We studied the performance of different dual-shaft eccentric mixers at the constant power input with its fluid velocity profiles, average shear strain rate, mixing time and mixing energy. The counter-rotation mode shows better mixing performance than co-rotation mode, and greater eccentricity can shorten mixing time on the basis of same stirred condition. To intensify the hydrodynamic interaction between impellers and enhance the overall mixing performance of the dual shaft eccentric mixers, it is critical to have a reasonable combination of impellers and an appropriate spatial position of impellers.

Carbon catalysts for propane oxidative dehydrogenation (PODH) can potentially replace metal oxide catalysts due to their environmental friendliness (greenness) and excellent catalytic performance. Biomass carbon materials have the advantages of being abundant in variety, inexpensive, and easily available, but their catalytic selectivity is relatively poor in PODH. Therefore, we report here on a boron-doped sisal fiber carbon catalyst, which showed excellent selectivity of propylene in PODH, excluding the effect of surface-covered B₂O₃ on the catalytic performance by hot water washing. The carbon material exhibited the best catalytic performance with a load of 2% (mass) and a calcination temperature of 1100 ℃. At a reaction temperature of 400 ℃, the conversion rate of propane was 2.0%, and the selectivity toward propylene reached 88.6%. The new chemical bonds formed by boron on the surface of the carbon materials had an important effect on the catalytic performance, as determined by XPS characterization. The B-O groups affected the catalytic activity by inhibiting the generation of electrophilic oxygen species, while the B-C content improved the selectivity toward propylene by changing the electron cloud density.