Development of a CH4 dehydroaromatization–catalyst regeneration fluidized bed system

A pilot-scale methane dehydroaromatization–H₂ regeneration fluidized bed system (MDARS) was developed. In the MDARS, the catalyst circulation between a fluidized bed reactor and a fluidized bed regenerator with the help of a catalyst feeder allowed methane dehydroaromatization (MDA) and H₂ regeneration to be carried out simultaneously, which is good for maintaining a stable MDA catalytic activity. A fixed bed reactor (FB) and a single fluidized bed reactor (SFB) were also used for a comparative study. The experimental results showed that the catalytic activity in the MDARS was more stable than that in the FB and SFB reactors. The effects of some parameters of MDARS on the CH₄ conversion and product selectivity were investigated. To verify the feasibility and reliability of the MDARS, an eight-hour long-term test was carried out, which demonstrated that the operation of the MDARS was stable and that the catalytic activity remained stable throughout the entire experimental period.     

First example of a Rh–N–C–O–P heterocycle – a rare example of a five membered true heterocycle

A novel ligand containing an N–C–O–P backbone has been prepared and used to form a rare example of a ‘true heterocycle’ containing a Rh–N–C–O–P ring.     

Hydrogen-storage properties of MgH2–10Ni–2NaAlH4–2Ti–2CNT milled in a planetary ball mill under H2

A sample with a composition of 84 wt% MgH₂–10 wt% Ni–2 wt% NaAlH₄–2 wt% Ti–2 wt% CNT (named MgH₂–10Ni–2NaAlH₄–2Ti–2CNT) was prepared by milling in a planetary ball mill under H₂. Activation of the sample was not required. At the first cycle, the sample absorbed 3.75 wt% H for 10 min, and 4.17 wt% H for 60 min at 593 K under 12 bar H₂. Reactive mechanical grinding of Mg with Ni, NaAlH₄, Ti, and CNT is thought to create defects on the surface and in the interior of Mg, as well as to reduce Mg particle size.     

4–氨基–1,2,4–三唑硝酸盐的合成及晶体结构研究

以甲酸和水合肼为原料,经甲酰化、环化、酸化合成了4–氨基–1,2,4–三唑硝酸盐(4–ATN),收率97.2%。采用IR、1H–NMR、质谱、元素分析及四圆单晶衍射仪等手段对目标化合物进行了表征,并进行了热性能分析。结果表明:4–ATN晶体属单斜晶系,存在分子内和分子间氢键。空间群为Cc,晶胞参数:a=0.955 1(4)nm,b=0.524 5(2)nm,c=1.181 0(5)nm;α=90°,β=96.627(6)°,γ=90°;V=0.587 7(4)nm3,Dc=1.663 g/cm3,Z=4,μ=0.151 mm–1,F(000)=304,μ(Mo Kα)=1.109 mm–1,R1=0.034 2,wR2=0.106 1。     

Feasibility of SiAlON–Si3N4 composite ceramic as a potential bone repairing material

In this study, SiAlON–Si₃N₄ composite ceramic are prepared by direct nitridation and investigated to overcome the limitations associated with ceramic Si₃N₄, which includes the difficulty in fabricating ceramic Si₃N₄ into shaped parts for use in the human body. Phase composition and microstructure of the SiAlON–Si₃N₄ composites were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively, and the porosity, bulk density, compressive strength, and ion release were also measured. The biological properties were evaluated by bone cell cultures on the ceramic surfaces. Results show that Si₄Al₂O₂N₆ is formed by the reaction of Al, Si, and Al₂O₃ with nitrogen at high temperature that forms Si₃N₄, thereby fabricating SiAlON–Si₃N₄ composite ceramics. Some α-Si₃N₄ grains underwent a phase transition from α-to β-Si₃N₄ fiber at high temperature. Porosity of the samples increases with increasing Si₃N₄ content, while the bulk density of the samples decreases. The compressive strength increases and then slightly decreases with increasing Si₃N₄ content. Water leaching experiments of the SiAlON–Si₃N₄ composite ceramics reveal that the composites exhibit outstanding chemical stability. Studies using bone cell culture indicate that the cells present a fusiform and extend two or three thin pseudopodia. The phenomena demonstrate that MC3T3-E1 cells have excellent growth activity and have the potential ability to proliferate to osteocytes on the surfaces of the samples, thus suggesting that SiAlON–Si₃N₄ based ceramics are biocompatible and could be implemented as a potential bone-repairing material.     

Syntheses,structures and properties of a series of 3s–5d–4f mixed metal substituted sandwich-type arsenotungstates

A class of 3s–5d–4f mixed metal substituted sandwich-type arsenotungstates [H₂N(CH₃)₂]₈H₃[LnNa(H₂O)₄(OH)WO(H₂O) (B-α-AsW₉ O₃₃)₂]·8H₂O [Ln = La^III (1), Ce^III (2), Pr^III (3)] have been isolated from an aqueous solution reaction system (pH = 4) of Na₂WO₄·2H₂O, C₂H₇N·HCl, NaAsO₂ and Ln(NO₃)₃·6H₂O and structurally characterized by elemental analyses, IR spectra, UV spectra and single-crystal X-ray diffraction. It is the most prominent in 1–3 that the [LnNa(H₂O)₄(OH) WO(H₂O)(B-α-AsW₉O₃₃)₂]^11 − polyanion consists of two trivacant Keggin [B-α-AsW₉O₃₃]^9 − moieties linked by one [WO(H₂O)]^4 + group and a dimeric [LnNa(H₂O)₄(OH)]^3 + group resulting in the special 3s–5d–4f mixed metal substituted sandwich-type assembly. Interestingly, lanthanide and sodium ions simultaneously occupy the two positions located at the central belt of 1–3 with the site occupancy of 50% for each position. Moreover, the electrochemical and electrocatalytic properties of only 1 and 2 have been measured by cyclic voltammetry (CV) in 0.5 mol·L^− 1 Na₂SO₄ + H₂SO₄ aqueous solution. 1 and 2 illustrate electrocatalytic activities for the hydrogen peroxide reduction.     

4–氨基–3,5–二硝基吡唑有机胺盐合成与性能

以4–氨基–3,5–二硝基吡唑（ADNP）为原料,合成了ADNP的胍盐（GADNP）、三氨基胍盐（TAGADNP）、脒基脲盐（GUADNP）等3种新化合物,并用红外光谱、核磁共振光谱、元素分析等鉴定了结构。测试了GADNP、TAGADNP、GUADNP热安定性、密度与燃烧热,计算了生成焓与爆轰参数。结果表明,ADNP的有机胺盐分解温度与ADNP相比明显提高,TAGADNP热安定性好、生成焓和能量较高。     

Research Regarding a Correlation Core–Shell Morphology–Thermal Stability of Silica–Silver Nanoparticles

Silica nanoparticles repeatedly inhaled lead to acute and chronic lung inflammation and finally to pulmonary fibrosis and lung cancer, people with chronic respiratory diseases like asthma or allergic rhinitis being even more susceptible to their toxic effects. In order to reduce these above-mentioned toxic effects, the aim of this study was to engineer the environmental silica nanoparticles with silver and subsequent thermal treatment. Nanometer-sized and spherical silica particles were synthesized in a homogeneous state, using a simple one-pot chemical method. An applicable approach resulted in silver particles forming over the surface of the silica. The outcome was materialized in extremely small silver particles attached to silica core particles. Playing their well-known decisive role, precursors and catalysts effectively controlled the size of silver and silica particles. The synchronized structure of the synthesized particles was revealed by the electrostatic repulsion among the silica spheres and the electrostatic attraction between silica spheres and silver particles. The morphological images are revealed by means of a scanning electron microscope. The formation of silver–silica composite particles was confirmed by using infrared spectroscopy and X-ray photoelectron spectroscopy analysis. Following thermal analysis, the results concerning the thermal stability of the prepared particles provided higher temperature applications.     

Hollow core–shell ZnMn2O4 microspheres as a high-performance anode material for lithium-ion batteries

The hollow core–shell ZnMn₂O₄ microspheres are successfully prepared by a solvothermal carbon templating method and then a annealing process. The crystal phase and particle morphology of resultant ZnMn₂O₄ microspheres are characterized by XRD and TEM. The electrochemical properties of the ZnMn₂O₄ microspheres as an anode material are investigated for lithium ion batteries. The results show that the ZnMn₂O₄ microspheres exhibit a reversible capacity of 855.8 mA h g⁻¹ at a current density of 200 mA g⁻¹ after 50 cycles. Even at 1000 mA g⁻¹, the reversible capacity of the ZnMn₂O₄ microspheres is still kept at 724.4 mA h g⁻¹ after 60 cycles. The enhanced electrochemical performance suggests the promising potential of the hollow core–shell ZnMn₂O₄ microspheres in lithium-ion batteries.     

LiMn2O4–y Br y Nanoparticles Synthesized by a Room Temperature Solid-State Coordination Method

LiMn₂O_4–y Br _y nanoparticles were synthesized successfully for the first time by a room temperature solid-state coordination method. X-ray diffractometry patterns indicated that the LiMn₂O_4–y Br _y powders were well-crystallized pure spinel phase. Transmission electron microscopy images showed that the LiMn₂O_4–y Br _y powders consisted of small and uniform nanosized particles. Synthesis conditions such as the calcination temperature and the content of Br⁻ were investigated to optimize the ideal condition for preparing LiMn₂O_4–y Br _y with the best electrochemical performances. The optimized synthesis condition was found in this work; the calcination temperature is 800 °C and the content of Br⁻ is 0.05. The initial discharge capacity of LiMn₂O_3.95Br_0.05 obtained from the optimized synthesis condition was 134 mAh/g, which is far higher than that of pure LiMn₂O₄, indicating introduction of Br⁻ in LiMn₂O₄ is quite effective in improving the initial discharge capacity.     

Production of C4 hydrocarbons from Fischer–Tropsch synthesis in a follow bed reactor consisting of Co–Ni–ZrO2 and sulfated-ZrO2 catalyst beds

Fischer–Tropsch synthesis was performed in a fixed-bed microreactor over a single bed consisting of Co–Ni–ZrO₂ catalyst as well as over a follow bed configuration consisting of Co–Ni–ZrO₂ and sulfated-ZrO₂ catalyst beds for the selective production of C₄ hydrocarbons. A maximum C₄ hydrocarbon selectivity of 14.6 wt.% was obtained using the single bed approach at 250°C and weight hourly space velocities (WHSV) of 15 h⁻¹. When a follow bed approach was used, there was an impressive increase in the selectivity for C₄ hydrocarbons to a maximum of 24 wt.% and that for iso-C₄ hydrocarbons to a maximum of 13.8 wt.% from 14.6 and 5.5 wt.%, respectively. However, there was a rapid deactivation of the sulfated-ZrO₂ catalyst due to coking and sulfate reduction.     

Detonation combustion of a hydrogen–oxygen mixture in a plane–radial combustor with exhaustion toward the center

Regimes of continuous spin detonation in a plane–radial combustor with an external diameter of 80 mm with peripheral injection of a hydrogen–oxygen mixture in the range of specific flow rates of the mixture 3.6–37.9 kg/(s ·m²) are obtained for the first time. Depending on the diameter of the exit orifice in the combustor (40, 30, or 20 mm), specific flow rate of the mixture, its composition, and counterpressure, one to seven transverse detonation waves with a frequency from 6 to 60 kHz are observed. It is found that the number of detonation waves increases, while their intensity decreases owing to reduction of the exit orifice diameter or to an increase in the counterpressure. The flow structure in the region of detonation waves is analyzed. The domain of detonation regimes in the coordinates of the fuel-to-air equivalence ratio and specific flow rate of the mixture is constructed. A physicomathematical model of continuous spin detonation in a plane–radial combustor is formulated. For parameters of hydrogen and oxygen injection into the combustor identical to experimental conditions, the present simulations predict similar parameters of detonation waves, in particular, the number of waves over the combustor circumference and the wave velocity.     

Effect of a NiO Additive on Interaction in a Ni–Al–W System in Self-Propagating High-Temperature Synthesis

An effect of a NiO additive on the combustion and structure formation in a Ni–Al–W system in self-propagating high-temperature synthesis (SHS) is under study. The stages of the combustion of compositions containing a NiO high-energy additive are shown. The interaction of W particles with Ni–Al melts during SHS results in the formation of globular decoration of particles on the basis of solid solutions of tungsten on the particle surface. This effect is observed only in compositions with an equimolar mixture of Ni–Al. With an NiO additive content in the initial sample more than 1 at.%, the globular decoration on the unreacted W particle surface does not occur. This effect can be associated with changes in the combustion temperature, deviation of the NiAl phase in the direction of a larger content of Ni, and the influence of oxide phases on diffusion processes.     

Micromixing in a gas–liquid vortex reactor

The gas–liquid vortex reactor (GLVR) has substantial process intensification potential for multiphase processes. Essential in this respect is the micromixing efficiency, which is of great importance in fast reaction systems such as crystallization, polymerization, and synthesis of nanomaterials. By creating a vortex flow and taking advantage of the centrifugal force field, the liquid micromixing process can be intensified in the GLVR. Results show that introducing a liquid into a gas-only vortex unit results in suppression of primary and secondary gas flow. The Villermaux–Dushman protocol is applied to study the effects of the gas flow rate, liquid flow rate, and liquid viscosity based on a segregation index. Based on the incorporation model and reaction kinetics, the micromixing time of the GLVR is determined to be in the range of 10⁻⁴ ~ 10⁻³ s, which is comparable to the highly efficient rotating packed bed and substantially better than a static mixer.     

Euler multiphase-CFD simulation on a bubble-driven gas–liquid–solid fluidized bed

An integrated flow model was developed to simulate the fluidization hydrodynamics in a new bubble-driven gas–liquid–solid fluidized bed using the computational fluid dynamic (CFD) method. The results showed that axial solids holdup is affected by grid size, bubble diameter, and the interphase drag models used in the simulation. Good agreements with experimental data could be obtained by adopting the following parameters: 5 mm grid, 1.2 mm bubble diameter, the Tomiyama gas–liquid model, the Schiller–Naumann liquid–solid model, and the Gidaspow gas–solid model. At full fluidization state, an internal circulation of particles flowing upward near the wall and downward in the centre is observed, which is in the opposite direction compared with the traditional core-annular flow structure in a gas–solid fluidized bed. The simulated results are very sensitive to bubble diameters. Using smaller bubble diameters would lead to excessive liquid bed expansions and more solid accumulated at the bottom due to a bigger gas–liquid drag force, while bigger bubble diameters would result in a higher solid bed height caused by a smaller gas–solid drag force. Considering the actual bubble distribution, population balance model (PBM) is employed to characterize the coalescence and break up of bubbles. The calculated bubble diameters grow up from 2–4 mm at the bottom to 5–10 mm at the upper section of the bed, which are comparable to those observed in experiments. The simulation results could provide valuable information for the design and optimization of this new type of fluidized system.     

3–(3,5–二叔丁基–4–羟基苯基)丙酸甲酯及新型抗氧剂的合成

简述了3–(3,5–二叔丁基–4–羟基苯基)丙酸甲酯的合成方法及以其为原料合成新型抗氧剂的方法,介绍了部分新型抗氧剂品种及性能。     

Ignition of a Ti–Al–C System by an Electron Beam

This paper describes the optimal modes of initiation of self-propagating hightemperature synthesis with the help of an electron beam on the example of a Ti–Al–C powder mixture. A pulsed electron beam with a particle energy of tens of kiloelectronvolts and a duration of hundreds of microseconds is used. Morphology, structure, and elemental composition of formed products in the form of Ti₃AlC₂ and TiC are studied.