The catalytic hydrogenation of 2-nitro-4-acetylamino anisole (NMA) is a less-polluting and efficient method to produce 2-amino-4-acetamino anisole (AMA). However, the kinetics of catalytic hydrogenation of NMA to AMA remains obscure. In this work, the kinetic models including power-law model and Langmuir-Hinshelwood-Hougen-Watson (LHHW) model of NMA hydrogenation to AMA catalyzed by Raney nickel catalyst were investigated. All experiments were carried out under the elimination of mass transfer resistance within the temperature range of 70–100 ℃ and the hydrogen pressure of 0.8–1.5 MPa. The reaction was found to follow 0.52-order kinetics with respect to the NMA concentration and 1.10-order kinetics in terms of hydrogen pressure. Based on the LHHW model, the dual-site dissociation adsorption of hydrogen was analyzed to be the rate determining step. The research of intrinsic kinetics of NMA to AMA provides the guidance for the reactor design and inspires the catalyst modification.

Novel organo-inorganic hybrid materials (MTW-x-SO₃H) have been fabricated by immobilizing 3-mercaptopropyltriethoxysilane onto mesopore MTW zeolites, which is treated via a simple oxidation process with hydrogen peroxide as the oxidant to transform sulfhydryl group into sulfonic acid group. The organic sulfhydryl groups are covalently bonded to the external surface of MTW zeolites through the condensation between siloxane arising from organic fragments with silanol groups on the surface of MTW zeolites, the hybrids contain sulfonic acid group within the external surface of MTW zeolites and an opened mesoporous system in the matrix of MTW zeolites, which provide enough accessible Brønsted acid sites for the alkylation between phenol with tert-butyl alcohol. Through this methodology it’s possible to prepare multifunctional materials where the plenty of mesopores are benefit for the introduction of larger numbers of sulfonic acid groups that contributes to activity during reactions, resulting in high activity (>55%) of MTW-4-SO₃H and desired selectivity (>56%) of 2-TBP (2-tert-butyl phenol) in the alkylation between phenol with tert-butyl alcohol.

Sodium-contained compounds are promising sintering additives for the low-temperature preparation of reaction bonded SiC membranes. Although sodium-based sintering additives in various original states were attempted, their effects on microstructure and surface properties have rarely been studied. In this work, three types of sodium-based additives, including solid-state NaA zeolite residue (NaA) and liquid-state dodecylbenzene sulfonate (SDBS) and water glass (WG), were separately adopted to prepare SiC membranes, and the microstructure, surface characteristics and filtration performance of these SiC membranes were comparatively studied. Results showed that the SiC membranes prepared with liquid-state SDBS and WG (S-SDBS and S-WG) showed lower open porosity yet higher bending strength compared to those prepared with solid-state NaA (S-NaA). The observed differences in bending strength were further interpreted by analyzing the reaction process of each sintering additive and the composition of the bonding phase in the reaction bonded SiC membranes. Meanwhile, the microstructural differentiation was correlated to the original state of the additives. In addition, their surface characteristics and filtration performance for oil-in-water emulsion were examined and correlated to the membrane microstructure. The S-NaA samples showed higher hydrophilicity, lower surface roughness (1.80 μm) and higher rejection ratio (99.99%) in O/W emulsion separation than those of S-WG and S-SDBS. This can be attributed to the smaller mean pore size and higher open porosity, resulting from the originally solid-state NaA additives. Therefore, this work revealed the comprehensive effects of original state of sintering additives on the prepared SiC membranes, which could be helpful for the application-oriented fabrication by choosing additives in suitable state.

The Co₃O₄ nanoparticles, dominated by a catalytically active (110) lattice plane, were synthesized as a low-temperature NO_x adsorbent to control the cold start emissions from vehicles. These nanoparticles boast a substantial quantity of active chemisorbed oxygen and lattice oxygen, which exhibited a NO_x uptake capacity commensurate with Pd/SSZ-13 at 100°C. The primary NO_x release temperature falls within a temperature range of 200–350°C, making it perfectly suitable for diesel engines. The characterization results demonstrate that chemisorbed oxygen facilitate nitro/nitrites intermediates formation, contributing to the NO_x storage at 100°C, while the nitrites begin to decompose within the 150–200°C range. Fortunately, lattice oxygen likely becomes involved in the activation of nitrites into more stable nitrate within this particular temperature range. The concurrent processes of nitrites decomposition and its conversion to nitrates results in a minimal NO_x release between the temperatures of 150–200°C. The nitrate formed via lattice oxygen mainly induces the NO_x to be released as NO₂ within a temperature range of 200–350°C, which is advantageous in enhancing the NO_x activity of downstream NH₃-SCR catalysts, by boosting the fast SCR reaction pathway. Thanks to its low cost, considerable NO_x absorption capacity, and optimal release temperature, Co₃O₄ demonstrates potential as an effective material for passive NO_x adsorber applications.

Biochar is a reactive carrier as it may be partially gasified with steam in steam reforming, which could influence the formation of reaction intermediates and modify catalytic behaviors. Herein, the Ni/biochar as well as two comparative catalysts, Ni/Al₂O₃ and Ni/SiO₂, with low nickel loading (2% (mass)) was conducted to probe involvement of the varied carriers in the steam reforming. The results indicated that the Ni/biochar performed excellent catalytic activity than Ni/SiO₂ and Ni/Al₂O₃, as the biochar carrier facilitated quick conversion of the -OH from dissociation of steam to gasify the oxygen-rich carbonaceous intermediates like C=O and C-O-C, resulting in low coverage while high exposure of nickel species for maintaining the superior catalytic performance. In converse, strong adsorption of aliphatic intermediates over Ni/Al₂O₃ and Ni/SiO₂ induced serious coking with polymeric coke as the main type (21.5% and 32.1%, respectively), which was significantly higher than that over Ni/biochar (3.9%). The coke over Ni/biochar was mainly aromatic or catalytic type with nanotube morphology and high crystallinity. The high resistivity of Ni/biochar towards coking was due to the balance between formation of coke and gasification of coke and partially biochar with steam, which created developed mesopores in spent Ni/biochar while the coke blocked pores in Ni/Al₂O₃ and Ni/SiO₂ catalysts.

With the increasing demand for high-purity products, the industrial application of melt crystallization technology has been highly concerned. In this study, the purification process of nitrochlorobenzene binary eutectic system (NBES) and naphthalene–benzothiophene solid solution system (NBSSS) in tower melting crystallizer is analyzed, and a mathematical model of crystallization process is established. The key parameters in terms of feed concentration, crystal bed height, reflux ratio and stirring speed efficiency on purification effects were discussed by the established model. The results show that the concentration of p-nitrochlorobenzene was purified from 90.85% to 99.99%, when the crystal bed height is 600 mm, the reflux ratio is 2.5, and the stirring speed is 12 r·min^-1. The naphthalene concentration is purified from 95.89% to 99.99%, when the crystal bed height is 400 mm, the reflux ratio is 1.43, and the stirring speed is 16 r·min^-1. The quality of the model is evaluated by the ARD (average relative deviation). The minimum ARD values of the NBES and NBSSS are 2.39% and 5.22%, respectively, indicating the model satisfactorily explains the purification process.

In this study, ferric nitrate modified carbon nanotube composites (FCNT) were prepared by isovolumetric impregnation using carbon nanotubes (CNTs) as the carrier and ferric nitrates the active agent. The batch experiments showed that FCNT could effectively oxidize As(III) to As(V) and react with it to form stable iron arsenate precipitates. When the dosage of FCNT was 0.1 g·L^-1, pH value was 5-6, reaction temperature was 35 ℃ and reaction time was 2 h, the best arsenic removal effect could be achieved, and the removal rate of As(V) could reach 99.1%, which was always higher than 90% under acidic conditions. The adsorption results of FCNT were found to be consistent with Langmuir adsorption by static adsorption isotherm fitting, and the maximum adsorption capacity reached 118.3 mg·g^-1. The material phase and property analysis by scanning electron microscopy, Brunauer-Emmett-Teller, Fourier transform infrared spectoscopy, X-ray photoelectron spectroscopy and other characterization methods, as well as adsorption isotherm modeling, were used to explore the adsorption mechanism of FCNT on arsenic. It was found that FCNT has microporous structure and nanostructure, and iron nanoparticles are loosely distributed on CNTs, which makes the material have good oxidation, adsorption and magnetic separation properties. Arsenic migrates on the surface of FCNT composites is mainly removed by forming insoluble compounds and co-precipitation. All the results show that FCNT treats arsenic at low cost with high adsorption efficiency, and the results also provide the experimental data basis and theoretical basis for arsenic contamination in groundwater.

The flow and heat transfer characteristics of n-decane in the sub-millimeter spiral tube (SMST) at supercritical pressure (p = 3 MPa) are studied by the RNG k -ε numerical model in this paper. The effects of various Reynolds numbers (Re) and structural parameters pitch (s) and spiral diameter (D) are analyzed. Results indicate that the average Nusselt number (f) and friction factor (Nu) increase with an increase in Re, and decrease with an increase in D/d (tube diameter). In terms of the structural parameter s/d, it is found that as s/d increases, the Nu and f first increase, and then decrease. and the critical structural parameter is s/d = 4. Compared with the straight tube, the SMST can improve Nu by 34.8% at best, while it can improve f by 102.1% at most. In addition, a comprehensive heat transfer coefficient is applied to analyze the thermodynamic properties of SMST. With the optimal structural parameters of D/d = 6 and s/d = 4, the comprehensive heat transfer factor of supercritical pressure hydrocarbon fuel in the SMST can reach 1.074. At last, correlations of the average Nusselt number and friction factor are developed to predict the flow and heat transfer of n-decane at supercritical pressure.

Copper was extracted from methylchlorosilane slurry residue by a direct hydrogen peroxide leaching method. A number of experimental parameters were analyzed to determine the extraction efficiency of copper. The extraction efficiency of copper reached 98.5% under the optimal leaching conditions, such as the hydrogen peroxide concentration of 1.875 mol·L^-1, the leaching temperature of 323 K, the liquid-solid ratio of 20 ml·g^-1, and the stirring speed of 300 r?min^-1. The leaching kinetics of the copper extraction process was then described by the shrinking core model. There were two stages. The first stage was controlled by chemical reactions, while the second stage was controlled by interface transfer and product layer diffusion. The activation energy and kinetic control equations were determined, as well as an explanation of the leaching mechanism of copper extraction based on kinetic analysis and materials characterization. Copper resources can be recovered from the methylchlorosilane slurry residue efficiently and inexpensively with the methods used in this study.

Arsenic is one of the main harmful elements in industrial wastewater. How to remove arsenic has always been one of the research hotspots in academic circles. In the process of arsenic removal by traditional sulfuration, the use of traditional sulfurizing agent will introduce new metal cations, which will affect the recycling of acid. In this study, phosphorus pentasulfide (P₂S₅) was used as sulfurizing agent, which hydrolyzed to produce H₃PO₄ and H₂S without introducing new metal cations. The effect of ultrasound on arsenic removal by P₂S₅ was studied. Under the action of ultrasound, the utilization of P₂S₅ was improved and the reaction time was shortened. The effects of S/As molar ratio and reaction time on arsenic removal rate were investigated under ultrasonic conditions. Ultrasonic enhanced heat and mass transfer so that the arsenic removal rate of 94.5% could be achieved under the conditions of S/As molar ratio of 2.1:1 and reaction time of 20 min. In the first 60 min, under the same S/As molar ratio and reaction time, the ultrasonic hydrolysis efficiency of P₂S₅ was higher. This is because P₂S₅ forms ([(P₂S₄)])²⁺ under the ultrasonic action, and the structure is damaged, which is easier to be hydrolyzed. In addition, the precipitation after arsenic removal was characterized and analyzed by X-ray diffraction, scanning electron microscope-energy dispersive spectrometer, X-ray fluorescence spectrometer and X-ray photoelectron spectroscopy. Our research avoids the introduction of metal cations in the arsenic removal process, and shortens the reaction time.

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.

A phosphorus-containing flame retardant, aluminum hypophosphite (AHPi), has been modified by (3-aminopropyl) triethoxysilane (KH550) to prepare flame-retardant polystyrene (PS). The influence of modified AHPi on the morphology and characterization was investigated, and differences in flame retardant properties of the PS/AHPi and PS/modified AHPi were compared. The PS composite can pass the vertical burning tests (UL-94 standard) with a V-0 rating when the mass content of modified AHPi reaches 20%, compared with the mass content of 25% AHPi. The element mapping of the PS composite shows that modified AHPi has better dispersion in PS than AHPi. Thermogravimetric analysis results indicated that adding modified AHPi can advance the initial decomposition temperature of the composite material. With the addition of modified AHPi, the decrease in peak heat release rate (pHRR) is more evident than AHPi, and the char yield of the resultant PS composites gradually increased. With the addition of 25% modified AHPi, the pHRR and total heat release of PS composites decreased by 81.4% and 37.6%. The modification of AHPi promoted its dispersion in the PS matrix and improved the char formation of PS composites. The results of real-time infrared spectrometry of PS composites, Fourier transform infrared spectra and X-ray photoelectron analysis of the char layer indicated that modified AHPi has flame retardancy in condensed and gas phases.

Molecularly imprinted polymers (MIPs) have great potential as adsorbents for selective adsorption and separation of nucleoside compounds, but effectively enhancing the affinity of recognition sites by adjusting the forces between template molecules and functional monomers remains an important challenge. In this work, a surface imprinting strategy was used to construct bowl-shaped molecularly imprinted composite sorbents (BHPN@MIPs) based on polydopamine (PDA) particles and have achieved selective separation and purification of 2'-deoxyadenosine (dA). Where by the base complementary pairing interaction of the combined template molecule dA and the pyrimidine functional monomer can enhance the pre-assembly force, and the hydrophilic bowl-shaped PDA can provide a larger storage space contact efficiency of dA in the test solution, causing the site utilization much higher and improving the kinetic adsorption performance. The equilibrium adsorption time and maximum adsorption capacity of 60 min and 328.45 μmol·g^-1 were observed by static adsorption experiments, and the selectivity experimental results showed an imprinting factor IF of 1.30. After four adsorption-desorption cycles, the initial adsorption equilibrium adsorption capacity of BHPN@MIPs still retained 91.14%. By evaluating the selective adsorption of dA in spiked human serum solutions, BHPN@MIPs can be used to selectively enrich and analyze target dA in complex biological samples.

The improper disposal of spent selective catalytic reduction (SCR) catalysts causes environmental pollution and metal resource waste. A novel process to recover anatase titanium dioxide (TiO₂) from spent SCR catalysts was proposed. The process included alkali (NaOH) hydrothermal treatment, sulfuric acid washing, and calcination. Anatase TiO₂ in spent SCR catalyst was reconstructed by forming Na₂Ti₂O₄(OH)₂ nanosheet during NaOH hydrothermal treatment and H₂Ti₂O₄(OH)₂ during sulfuric acid washing. Anatase TiO₂ was recovered by decomposing H₂Ti₂O₄(OH)₂ during calcination. The surface pore properties of the recovered anatase TiO₂ were adequately improved, and its specific surface area (SSA) and pore volume (PV) were 85 m²·g^-1 and 0.40 cm³·g^-1, respectively. The elements affecting catalytic abilities (arsenic and sodium) were also removed. The SCR catalyst was resynthesized using the recovered TiO₂ as raw material, and its catalytic performance in NO selective reduction was comparable with that of commercial SCR catalyst. This study realized the sustainable recycling of anatase TiO₂ from spent SCR catalyst.

Solubility enhancement has been a priority to overcome poor solubility with optoelectronic molecules for solution-processable devices. This study aims to obtain experimental data on the effect of particle sizes on the solubility properties of several typical optoelectronic molecules in organic solvents, including the solubility results of 1,3-bis(9-carbazolyl)benzene (mCP), 1,3,5-tris(1-phenyl-1H-benzimidazol-2-yl)benzene (TPBi) and 2-(4-tert-butylphenyl)-5-(4-biphenyl)-1,3,4-oxadiazole (PBD) in ethanol and acetonitrile, respectively. Nanoparticles of mCP, TPBi and PBD with sizes from dozens to several hundred nanometers were prepared by solvent antisolvent precipitation method and their solubility were determined by using isothermal saturation method. The saturation solubility of nanoparticles of three kinds of optoelectronic molecules exhibited increase of 12.9%-25.7% in comparison to the same raw materials in the form of microparticles. The experimental evidence indicates that nanonization technology is a feasible way to make optoelectronic molecules dissolve in liquids with enhanced solubility.

Tungsten (W) incorporated mobil-type eleven (MEL) zeolite membrane (referred to as W-MEL membrane) with high separation performance was firstly explored for the separation of oil/water mixtures under the influence of gravity. W-MEL membranes were grown on stainless steel (SS) meshes through in-situ hydrothermal growth method facilitated with (3-aminopropyl)triethoxysilane (APTES) modification of stainless steel meshes, which promote the heterogeneous nucleation and crystal growth of W-MEL zeolites onto the mesh surface. W-MEL membranes were grown on different mesh size supports to investigate the effect of mesh size on the separation performance of the membrane. The as-synthesized W-MEL membrane supported on 500 mesh (25 μm) (W-MEL-500) exhibit the hydrophilic nature with a water contact angle of 11.8° and delivers the best hexane/water mixture separation with a water flux and separation efficiency of 46247 L·m^-2·h^-1 and 99.5%, respectively. The wettability of W-MEL membranes was manipulated from hydrophilic to hydrophobic nature by chemically modifying with the fluorine-free compounds (hexadecyltrimethoxysilane (HDTMS) and dodecyltrimethoxysilane (DDTMS)) to achieve efficient oil-permselective separation of heavy oils from water. Among the hydrophobically modified W-MEL membranes, W-MEL-500-HDTMS having a water contact angle of 146.4° delivers the best separation performance for dichloromethane/water mixtures with a constant oil flux and separation efficiency of 61490 L·m^-2·h^-1 and 99.2%, respectively along with the stability tested up to 20 cycles. Both W-MEL-500-HDTMS and W-MEL-500-DDTMS membranes also exhibit similar separation performances for the separation of heavy oil from sea water along with a 20-fold lower corrosion rate in comparison with the bare stainless-steel mesh, indicating their excellent stability in seawater. Compared to the reported zeolite membranes for oil/water separation, the as-synthesized and hydrophobically modified W-MEL membranes shows competitive separation performances in terms of flux and separation efficiency, demonstrating the good potentiality for oil/water separation.

The heat transfer of hydrocarbon refrigerant across tube bundles have been widely used in refrigeration. Three-dimensional simulation model using volume of fluid (VOF) was presented to study the effects of tube shapes on flow pattern, film thickness and heat transfer of n-pentane across tube bundles, including circle, ellipse-shaped, egg-shaped and cam-shaped tube bundles. Simulation results agree well with experimental data in the literature. The liquid film thickness of sheet flow and heat transfer for different tube shapes were obtained numerically. The flow pattern transition occurs lower vapor quality for ellipse-shaped tube than other tube shapes. For sheet flow, the liquid film on circle tube and ellipse-shaped tube is symmetrically distributed along the circumferential direction. However, the liquid film on egg-shaped tube at circumferential angles (θ) = 15°-60° is thicker than θ = 135°-165°. The liquid film on cam tube at θ = 15°-60° is slightly thinner than θ = 135°-165°. The liquid film thickness varies from thinner to thicker for ellipse-shaped, cam-shaped, egg-shape and circle within θ = 15°-60°. The effect of tube shape is insignificant on thin liquid film thickness. Ellipse-shaped tube has largest heat transfer coefficient for sheet flow. In practical engineering, the tube shape could be designed as ellipse to promote heat transfer.

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.

Ensuring the consistency of electrode structure in proton-exchange-membrane fuel cells is highly desired yet challenging because of wide-existing and unguided cracks in the microporous layer (MPL). The first thing is to evaluate the homogeneity of MPL with cracks quantitatively. This paper proposes the homogeneity index of a full-scale MPL with an area of 50 cm², which is yet to be reported in the literature to our knowledge. Besides, the effects of the carbon material and surfactant on the ink and resulting MPL structure have been studied. The ink with a high network development degree produces an MPL with low crack density, but the ink with high PDI produces an MPL with low crack homogeneity. The polarity of the surfactant and the non-polarity of polytetrafluoroethylene (PTFE) are not mutually soluble, resulting in the heterogeneous PTFE distribution. The findings of this study provide guidelines for MPL fabrication.

The performance of pearlescent pigment significantly affected by the grain size and the roughness of deposited film. The effect of TiCl₄ concentration on the initial deposition of TiO₂ on mica by atmospheric pressure chemical vapor deposition (APCVD) was investigated. The precursor concentration significantly affected the deposition and morphology of TiO₂ grains assembling the film. The deposition time for fully covering the surface of mica decreased from 120 to 10 s as the TiCl₄ concentration increased from 0.38% to 2.44%. The grain size increased with the TiCl₄ concentration. The AFM and TEM analysis demonstrated that the aggregation of TiO₂ clusters at the initial stage finally result to the agglomeration of fine TiO₂ grains at high TiCl₄ concentrations. Following the results, it was suggested that the nucleation density and size was easy to be adjusted when the TiCl₄ concentration is below 0.90%.