Effect of bubble morphology and behavior on power consumption in non-Newtonian fluids’aeration process

Due to a prolonged operation time and low mass transfer efficiency, the primary challenge in the aeration process of non-Newtonian fluids is the high energy consumption, which is closely related to the form and rate of impeller, ventilation, rheological properties and bubble morphology in the reactor. In this perspective, through optimal computational fluid dynamics models and experiments, the relationship between power consumption, volumetric mass transfer rate(kLa) and initial bubble size(d0) was constructed to establish an efficient operation mode for the aeration process of non-Newtonian fluids. It was found that reducing the d0could significantly increase the oxygen mass transfer rate, resulting in an obvious decrease in the ventilation volume and impeller speed. When d0was regulated within 2-5 mm,an optimal kLa could be achieved, and 21% of power consumption could be saved, compared to the case of bubbles with a diameter of 10 mm.

A review of ^(17)O isotopic labeling techniques for solid-state NMR structural studies of metal oxides in lithium-ion batteries

Recent advances in utilizing ^(17)O isotopic labeling methods for solid-state nuclear magnetic resonance(NMR)investigations of metal oxides for lithium-ion batteries have yielded extensive insights into their structural and dynamic details.Herein,we commence with a brief introduction to recent research on lithium-ion battery oxide materials studied using ^(17)O solid-state NMR spectroscopy.Then we delve into a review of ^(17)O isotopic labeling methods for tagging oxygen sites in both the bulk and surfaces of metal oxides.At last,the unresolved problems and the future research directions for advancing the ^(17)O labeling technique are discussed.

KOH-assisted aqueous synthesis of ZIF-67 with high-yield and its derived cobalt selenide/carbon composites for high-performance Li-ion batteries

To solve the environmental pollution and low yield during the sythesis of zeolitic imidazolate frameworks(ZIFs)and their derived materials,a KOH-assisted aqueous strategy is proposed to synthesize cobalt zeolitic imidazolate framework(ZIF-67)polyhedrons,which are used as precursors to prepare cobalt selenide/carbon composites with different crystal phases(Co_(0.85)Se,CoSe_2).When evaluated as anode material for lithium ion batteries,Co_(0.85)Se/C composites deliver a reversible capacity of 758.7 m A·h·g^(-1)with a capacity retention rate of 90.5%at 1.0 A·g^(-1)after 500 cycles,and the superior rate capability is 620 m A·h·g^(-1)at 2.0 A·g^(-1).The addition of KOH accelerates the production of ZIF-67 crystals by boosting deprotonation of dimethylimidazole,resulting in rapid growth and structures transition from two-dimensional to three-dimensional of ZIF-67 in aqueous solution,which greatly promotes the application of MOFs in the field of energy storage and conversion.

2D black arsenic phosphorous

Since the successful exfoliation of graphene in 2014,twodimensional(2D)materials have explosively increased in the past few years[1].2D pnictogen materials with intriguing properties beyond graphene are gradually coming into eyesight,such as black phosphorous(BP)[2],arsenene[3],antimonene[4],bismuthine[5],etc.BP is a star material in 2D materials.

Mechanism of chain propagation for the synthesis of polyoxymethylene dimethyl ethers

Polyoxymethylene dimethyl ethers(PODE)were synthesized from the reaction of paraformaldehyde with dimethoxymethane(DMM)over different acid catalysts at different conditions.Products were found to follow the Schulz-Flory distribution law.The chain propagation proceeds through the insertion of an individual segment of CH2O one by one,while the simultaneous insertion of a few CH2O segments or their assembly is unlikely.Due to the restriction of this law,it is difficult to increase the selectivity to the desired products(e.g.,PODE3 4).

Permeability and Selectivity of Sulfur Dioxide and Carbon Dioxide in Supported Ionic Liquid Membranes

Permeabilities and selectivities of gases such as carbon dioxide(CO2),sulfur dioxide(SO2),nitrogen(N2)and methane(CH4)in six imidazolium-based ionic liquids([emim][BF4],[bmim][BF4],[bmim][PF6],[hmim][BF4],[bmim][Tf2N]and[emim][CF3SO3])supported on polyethersulfone microfiltration membranes are investigated in a single gas feed system using nitrogen as the environment and reference component at temperature from 25 to 45oC and pressure of N2 from 100 to 400kPa.It is found that SO2 has the highest permeability in the tested supported ionic liquid membranes,being an order of magnitude higher than that of CO2,and about 2 to 3 orders of magnitude larger than those of N2 and CH4.The observed selectivity of SO2 over the two ordinary gas components is also striking.It is shown experimentally that the dissolution and transport of gas components in the supported ionic liquid membranes,as well as the nature of ionic liquids play important roles in the gas permeation.A nonlinear increase of permeation rate with temperature and operation pressure is also observed for all sample gases.By considering the factors that influence the permeabilities and selectivities of CO2 and SO2,it is expected to develop an optimal supported ionic liquid membrane technology for the isolation of acidic gases in the near future.

Effect of loading on the Ni_2P/Al_2O_3 catalysts for the hydrotreating reactions

The 80%Ni2P/Al2O3 catalysts were prepared by the phosphidation of corresponding 80%Ni/Al2O3 with triphenylphosphine in liquid phase and compared with the 60%Ni2P/Al2O3 for hydrotreating reactions. Both the60%Ni2P/Al2O3 and 80%Ni2P/Al2O3 in comparison exhibited the small and uniform Ni2 P particles（6.3 and8.4 nm,respectively）,high CO uptakes（305 and 345 μmol/g,respectively） and thus high activities for the hydrotreating reactions. After the hydrotreating reactions,the small and uniform Ni2 P particles were remained,although the CO uptakes on the used 60%Ni2P/Al2O3 and 80%Ni2P/Al2O3 were greatly decreased（to 68 and95 μmol/g,respectively） due to the incorporation of S into the Ni2 P surfaces. The 80%Ni2P/Al2O3 was found to be significantly more active than the 60%Ni2P/Al2O3 due to that the 80%Ni2P/Al2O3 possessed more,and more active Ni2 P sites than the 60%Ni2P/Al2O3,probably due to the less S incorporated in the 80%Ni2P/Al2O3 than in the 60%Ni2P/Al2O3 during the hydrotreating reactions.

Preparation of Fe_2P/Al_2O_3 and FeP/Al_2O_3 catalysts for the hydrotreating reactions

A 60%Fe/Al_2O_3 catalyst was prepared by the co-precipitation method.It was reduced by H_2 to produce metallic Fe,which was then sulfided by CS_2 to Fe_(0.96) S and Fe_3S_4 or phosphided by triphenylphosphine(PPh3) in liquid phases to Fe2 P and Fe P.It was found that the iron sulfides(Fe0.96 S and Fe_3S_4) exhibited the low activity for the hydrodesulfurization(HDS) reactions.The HDS activity was also low on the Fe(metal)/Al_2O_3 and Fe_2 P/Al_2O_3 catalysts since they were converted into Fe0.96 S and Fe_3S_4 during the HDS reactions.In contrast,the FeP/Al_2O_3 was found to be stable and active for the HDS reactions.In particular,Fe P/Al_2O_3 possessed significantly smaller Fe P particles than Fe P/C,leading to the significant higher HDS activity of FeP/Al_2O_3 than Fe P/C.

Optimization of MgO/Al_2O_3 ratio for the maximization of active site densities in the Ni_2P/MgAlO catalysts for the hydrotreating reactions

The Ni2P/MgAlO catalysts with different MgO/Al2O3 ratios were prepared by the phosphidation of corresponding Ni/MgAlO catalysts with triphenylphosphine in liquid phase. It was found that the MgO/Al2O3 ratio affected the Ni2P/MgAlO catalysts significantly. The Ni2P/MgAlO catalyst with the MgO/Al2O3 ratio of 3 (w/w) exhibited the highly dispersed Ni2P particles (similar to 9 nm) with the highest CO uptake (344 mu mol/g) and thus the highest activities for the hydrotreating reactions. However, based on the CO uptakes on the used catalysts, the TOF values for the hydrodesulphurization of dibenzothiophene as well as those for the hydrogenation of tetralin on all the Ni2P/MgAlO catalysts were respectively similar, indicating that the MgO/Al2O3 ratio did not affect the intrinsic activities of Ni2P supported on the MgAlO support for the hydrotreating reactions. (C) 2016 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by Elsevier B.V. and Science Press. All rights reserved.

COMPOSITION DETERMINATION OF BINARY POLYMER MIXTURES BY SIZE EXCLUSION CHROMATOGRAPHY WITH LIGHT SCATTERING DETECTION

Base on the principle of absolute quantification of size exclusion chromatography （SEC）, a light scattering （LS） detector coupled with a concentration detector （refractive index detector） is utilized to determine the compositions of complicated binary mixtures. A theoretical analysis predicts that the response factors for both LS and RI detectors are linear functions with the composition of any specified polymer mixtures in the binary polymer mixtures. Two pairs of complicated binary mixtures were used to test the theory mentioned in the present paper, and the experimental results show an excellent accordance with the theory.

A comparison of H^+-restacked nanosheets and nanoscrolls derived from K_4Nb_6O_(17) for visible-light degradation of dyes

H＋-restacked nanosheets and nanoscrolls peeled from K4Nb6O17 display different structures and surface characters. The two restacked samples with increased surface areas have an amazing visible-light response for the photodegradation of dyes, which is superior to commercial TiO2 （P25） and Nb205. By comparison, H＋/nanosheets have a relatively faster photodegradation rate originated from large and smooth basal plane. The work reveals that dye adsorbed on the unfolded nanosheets can effectively harvest sunlight. Due to facile preparation, low-cost and high photocatalytic efficiency, H＋/nanosheets and H＋/nanoscrolls might be used for the visible light-driven degradation of organic dyes as a substitute for TiO2 in industry.

Insight into the promotional mechanism of Cu modification towards wide-temperature NH3-SCR performance of NbCe catalyst

A simple strategy of Cu modification was proposed to broaden the operation temperature window for NbCe catalyst.The best catalyst Cu0.010/Nb1Ce3 presented over 90%NO conversion in a wide temperature range of 200-400℃and exhibited an excellent H_(2)O or/and SO_(2) resistance at 275℃.To understand the promotional mechanism of Cu modification,the correlation among the"activity-structure-property"were tried to establish systematically.Cu species highly dispersed on NbCe catalyst to serve as the active component.The strong interaction among Cu,Nb and Ce promoted the emergence of NbO4 and induced more Bronsted acid sites.And Cu modification obviously enhanced the redox behavior of the NbCe catalyst.Besides,EPR probed the Cu species exited in the form of monomeric and dimeric Cu^(2+),the isolated Cu^(2+)acted as catalytic active sites to promote the reaction:Cu^(2+)-NO_(3)^(-)+NO(g)→Cu^(2+)-NO_(2)^(-)+NO_(2)(g).Then the generated NO_(2) would accelerate the fast-SCR reaction process and thus facilitated the lowtemperature deNO_(x) efficiency.Moreover,surface nitrates became unstable and easy to decompose after Cu modification,thus providing additional adsorption and activation sites for NH3,and ensuring the improvement of catalytic activity at high temperature.Since the NH3-SCR reaction followed by E-R reaction pathway efficaciously over Cu_(0.010)/Nb_(1)Ce_(3) catalyst,the excellent H_(2)O and SO_(2) resistance was as expected.

Efficient conversion of H_(2)S into mercaptan alcohol by tertiary-amine functionalized ionic liquids

The resource utilization of hydrogen sulfide(H_(2)S)is of great significance in natural gas chemical industry.Described herein have developed a novel method mediated in tertiary amine-functionalized ionic liquids(ILs)to convert H_(2)S into mercaptan alcohols with enols.The effect of ILs,substra te scope,and regeneration experiments have been investigated.It is found that the conversion of 3-methyl-2-buten-1-ol by H_(2)S can reach 52%with a 50%(mol)catalyst loading of bis(2-dimethylaminoethyl)ether methoxyacetate within 12 hat 90℃.The reaction mechanism was speculated based on theoretical calculation.Besides,a plausible reaction-separation-integrated strategy was further proposed.This work reveals an effective insight into the capture and catalytic conversion of H_(2)S to high valuable mercaptan alcohol,which makes the utilization method of H_(2)S resource universal and has the potentiality for industrial application.

Synthesis and Characterization of (4R,5R)-1,3-dioxolance-4,5-bis(2-pyridineacrboxylic acid)

The title compound, （4R,5R）-1,3-dioxolance-4,5-bis（2-pyridineacrboxylic acid）, has been synthesized and characterized by single-crystal X-ray diffraction, IR, NMR, and MS analyses. Crystal structure of the title compound was grown from ETOH by slow diffusion at room temperature. The title compound crystallizes in monoclinic, space group C2 with a = 17.805（3）, b = 11.459（3）, c = 11.1656（17） , β = 113.066（4）°, V = 2095.9（6） 3, Z = 4, F（000） = 880, Dc = 1.332 Mg/m-3, C23H20N2O6, Mr = 420.41 and μ = 0.10 mm-1

A green route for the preparation of layered double hydroxides from basic magnesium carbonate

Layered double hydroxides(LDHs)have received extensive attention in many fields such as catalysis,environmental management and medical applications.Typically,expensive soluble metal salts are commonly used as the starting materials for the synthesis of LDHs.Here,we report a novel synthesis route for Mg/Al-LDH by using inexpensive basic magnesium carbonate as the starting material.X-ray diffraction(XRD)and solid-state nuclear magnetic resonance(ssNMR)data show that LDHs with rich defects are formed rapidly at room temperature and good crystallinity can be obtained after further hydrothermal treatment.These results provide a simple,rapid and green preparation method for LDHs.

Core-shell structured Ru-Ni@SiO_2: Active for partial oxidation of methane with tunable H_2/CO ratio

This study demonstrated that a Ru-Ni bimetallic core-shell catalyst（0.6%Ru-Ni）@Si O2with a proper surface Ru concentration is superior in achieving better catalytic activity and tunable H2/CO ratio at a comparatively lower reaction temperature（700℃）.Compared to the impregnation method,the hydrothermal approach leads to a highly uniform Ru distribution throughout the core particles.Uniform Ru distribution would result in a proper surface Ru concentration as well as more direct Ru-Ni interaction,accounting for better catalyst performance.Enriched surface Ru species hinders surface carbon deposition,but also declines overall activity and H2/CO ratio,meanwhile likely enhances Ni oxidation to certain degree under the applied reaction conditions.Over the current（m%Ru-Ni）@Si O2catalyst,the formation of fibrous carbon species is suppressed,which accounts for good stability of catalyst within a TOS of 10 h.

Micro-interface enhanced mass transfer sodium carbonate absorption carbon dioxide reaction

Micro-interface intensified reactor(MIR)can be applied in series/parallel in the absorption of CO_(2)in industrial gases by Na_(2)CO_(3)due to the ability to produce large numbers of stable microbubbles.This work focuses on the variation pattern of mass transfer characteristics parameters of the reaction gas in Na_(2)CO_(3) solution under the influence of different solution properties and operating parameters in the reaction of CO_(2)absorption by Na2CO3.The mass transfer characteristics parameters include bubble Sauter mean diameter,gas holdup,interfacial area,liquid side mass transfer coefficient,and liquid side volume mass transfer coefficient kLa.The solution properties and operating parameters include Na2CO3 concentration(0.05–2.0 mol·L^(-1)),superficial gas velocity(0.00221–0.01989 m·s^(-1)),superficial liquid velocity(0.00332–0.02984 m·s^(-1)),and ionic strength(1.42456–1.59588 mol·kg^(-1)).And volumetric mass transfer coeffi-cients kLa and superficial reaction rates r of the MIR and the bubble column reactor are compared in the reaction of sodium carbonate absorption of carbon dioxide,and the former shows a greater improvement under different solution properties and operating parameters.The enhanced role of MIR in mass transfer in non-homogeneous reactions is verified and the feasibility of industrial practical applications of MIR is demonstrated.

Interface engineering in two-dimensional heterostructures towards novel emitters

Two-dimensional(2D) semiconductors have captured broad interest as light emitters, due to their unique excitonic effects. These layer-blocks can be integrated through van der Waals assembly, i.e., fabricating homo-or heterojunctions, which show novel emission properties caused by interface engineering. In this review, we will first give an overview of the basic strategies that have been employed in interface engineering, including changing components, adjusting interlayer gap, and tuning twist angle. By modifying the interfacial factors, novel emission properties of emerging excitons are unveiled and discussed. Generally, well-tailored interfacial energy transfer and charge transfer within a 2D heterostructure cause static modulation of the brightness of intralayer excitons. As a special case, dynamically correlated dual-color emission in weakly-coupled bilayers will be introduced, which originates from intermittent interlayer charge transfer. For homobilayers and type Ⅱ heterobilayers, interlayer excitons with electrons and holes residing in neighboring layers are another important topic in this review. Moreover, the overlap of two crystal lattices forms moiré patterns with a relatively large period, taking effect on intralayer and interlayer excitons. Particularly, theoretical and experimental progresses on spatially modulated moiré excitons with ultra-sharp linewidth and quantum emission properties will be highlighted. Moiré quantum emitter provides uniform and integratable arrays of single photon emitters that are previously inaccessible, which is essential in quantum many-body simulation and quantum information processing. Benefiting from the optically addressable spin and valley indices, 2D heterostructures have become an indispensable platform for investigating exciton physics, designing and integrating novel concept emitters.