Catalytically altering the redox pathway of sulfur in propylene carbonate electrolyte using dual-nitrogen/oxygen-containing carbon

Carbonate electrolytes are one of the most desirable electrolytes for high-energy lithium-sulfur batteries(LSBs)because of their successful implementation in commercial Li-ion batteries.The low-polysulfide-solubility feature of some carbonate solvents also makes them very promising for overcoming the shuttle effects of LSBs.However,regular sulfur electrodes experience undesired electrochemical mechanisms in carbonate electrolytes due to side reactions.In this study,we report a catalytic redox mechanism of sulfur in propylene carbonate(PC)electrolyte based on a compari-son study.The catalytic mechanism is characterized by the interactions between polysulfides and dual N/O functional groups on the host carbon,which largely prevents side reactions between polysulfides and the carbonate electrolyte.Such a mechanism coupled with the low-polysulfide-solubility feature leads to stable cycling of LSBs in PC electrolyte.Favorable dual N/O functional groups are identified via a density functional theory study.This work provides an alternative route for enabling LSBs in carbonate electrolytes.

Gas-solid catalytic reactions over ruthenium-based catalysts

Ruthenium （Ru）‐based catalysts are widely employed in several types of gas‐solid reactions because of their high catalytic activities. This review provides theoretical research on Ru‐based catalysts and an analysis of their basic properties and oxidation behavior. There is particular emphasis on Ru‐catalyzed gas‐solid catalytic reactions, including the catalytic oxidation of VOCs, preferential oxidation of CO, synthesis of ammonia, oxidation of HCl and partial oxidation of CH4. Recent litera‐ture on catalysis is summarized and compared. Finally, we describe current challenges in the field and propose approaches for future development of Ru‐based catalysts.

Ultralow charge-discharge voltage gap of 0.05 V in sunlight-responsive neutral aqueous Zn-air battery

Rechargeable neutral aqueous zinc-air batteries(ZABs)are a promising type of energy storage device with longer operating life and less corrosiveness compared with conventional alkaline ZABs.However,the neutral ZABs normally possess poor oxygen evolution reactions(OERs)and oxygen reduction reactions performance,resulting in a large charge–discharge voltage gap and low round-trip efficiency.Herein,we demonstrate a sunlight-assisted strategy for achieving an ultralow voltage gap of 0.05 V in neutral ZABs by using the FeOOH-decorated BiVO4(Fe-BiVO4)as an oxygen catalyst.Under sunlight,the electrons move from the valence band(VB)of Fe-BiVO_(4) to the conduction band producing holes in VB to promote the OER process and hence reduce the overpotential.Meanwhile,the photopotential generated by the Fe-BiVO_(4) compensates a part of the charging potential of neutral ZABs.Accordingly,the energy loss of the battery could be compensated via solar energy,leading to a record-low gap of 0.05 V between the charge and discharge voltage with a high round-trip efficiency of 94%.This work offers a simple but efficient pathway for solar-energy utilization in storage devices,further guiding the design of high energy efficiency of neutral aqueous ZABs.

Highly dispersed MgInCe-mixed metal oxides catalyzed direct carbonylation of glycerol and CO_(2)into glycerol carbonate

Glycerol carbonate,an important glycerol value-added product,has been widely used as an active intermediate and inert solvent in the synthesis of cosmetics,detergents,chemical intermediates,polymers,and so on.The direct carbonylation from glycerol with CO_(2)is considered a promising route,but still tough work due to the thermodynamic stability and the kinetic inertness of CO_(2).In this work,highlyselective direct carbonylation of glycerol and CO_(2)into glycerol carbonate has been achieved over highly dispersed MgInCe-mixed metal oxides(MgInCe-MMO),which were prepared through the topological transformation derived from the MgInCe-layered double hydroxides(MgInCe-LDHs).By precisely modulating the surface basic-acidic properties and the oxygen vacancies,an efficient carbonylation of glycerol with CO_(2)has been achieved with a selectivity of up to>99%to glycerol carbonate.Deep investigation into the synergistic catalysis of base-acid sites and oxygen vacancies has been clarified.

Bimetallic CoNi single atoms supported on three-dimensionally ordered mesoporous chromia:highly active catalysts for n-hexane combustion

Developing the alternative supported noble metal catalysts with low cost,high catalytic efficiency,and good resistance toward carbon dioxide and water vapor is critically demanded for the oxidative removal of volatile organic compounds(VOCs).In this work,we prepared the mesoporous chromia-supported bimetallic Co and Ni single-atom(Co_(1)Ni_(1)/meso-Cr_(2)O_(3))and bimetallic Co and Ni nanoparticle(Co_(NP)Ni_(NP)/mesoCr_(2)O_(3))catalysts adopting the one-pot polyvinyl pyrrolidone(PVP)-and polyvinyl alcohol(PVA)-protecting approaches,respectively.The results indicate that the Co_(1)Ni_(1)/meso-Cr_(2)O_(3)catalyst exhibited the best catalytic activity for n-hexane(C_(6)H_(14))combustion(T_(50%)and T_(90%)were 239 and 263℃ at a space velocity of 40,000 mL g^(-1)h^(-1);apparent activation energy and specific reaction rate at 260℃ were 54.7 kJ mol^(-1)and 4.3×10^(-7)mol g^(-1)_(cat)s^(-1),respectively),which was associated with its higher(Cr^(5+)+Cr^(6+))amount,large n-hexane adsorption capacity,and good lattice oxygen mobility that could enhance the deep oxidation of n-hexane,in which Ni_(1) was beneficial for the enhancements in surface lattice oxygen mobility and low-temperature reducibility,while Co_(1) preferred to generate higher contents of the high-valence states of chromium and surface oxygen species as well as adsorption and activation of n-hexane.n-Hexane combustion takes place via the Mars van Krevelen(MvK)mechanism,and its reaction pathways are as follows:n-hexane→olefins or 3-hexyl hydroperoxide→3-hexanone,2-hexanone or 2,5-dimethyltetrahydrofuran→2-methyloxirane or 2-ethyl-oxetane→acrylic acid→CO_x→CO_(2)and H_(2)O.

Study on Direct Synthesis of Diphenyl Carbonate with Heterogeneous Catalytic Reaction (V) Screening Catalysts and Optimizing Synthesis Conditions

Pd/LaxPbyMnOz, Pd/C, Pd/molecular sieve and Pd-heteropoly acid catalysts for direct synthesis of diphenyl carbonate (DPC) by heterogeneous catalytic reaction were compared and the results of DPC synthesis indicated that the catalyst Pd/LaxPbyMnOz had higher activity. The Pd/LaxPbyMnOz catalyst and the support was characterized by XRD, SEM and TEM, the main phase was Lao.szPbo.asMnOa and the average diameter could be about 25.4nm. The optimuna conditions for synthesis of DPC with Pd/LasPbyMnOz were determined by orthogonal experiments and the experimental results showed that reaction temperature was the first factor of effect on the selectivity and yield of DPC, and the concentration of O2 in gas phase also had significant effect on selectivity of DPC. The optimum reaction conditions were catalyst/phenol mass ratio l to 50, pressure 4.5MPa, volume concentration of O2 25%, reaction temperature 60℃ and reaction time 4 h. The maximum yield and average selectivity could reach 13% and 97% respectively in the batch operation.

CFD modeling of reaction and mass transfer through a single pellet: Catalytic oxidative coupling of methane

In this study a mathematical model of a small scale single pellet for the oxidative coupling of methane（OCM）over titanite pervoskite is developed.The method is based on a computational fluid dynamics（CFD）code which known as Fluent may be adopted to model the reactions that take place inside the porous catalyst pellet.The steady state single pellet model is coupled with a kinetic model and the intra-pellet concentration profiles of species are provided.Subsequent to achieving this goal,a nonlinear reaction network consisting of nine catalytic reactions and one gas phase reaction as an external program is successfully implemented to CFD-code as a reaction term in solving the equations.This study is based on the experimental design which is conducted in a differential reactor with a Sn/BaTiO3 catalyst（7-8 mesh） at atmospheric pressure,GHSV of 12000 h-1,ratio of methane to oxygen of 2,and three different temperatures of 1023,1048 and 1073 K.The modeling results such as selectivity and conversion at the pellet exit are in good agreement with the experimental data.Therefore,it is suggested that to achieve high yield in OCM process the modeling of the single pellet should be considered as the heart of catalytic fixed bed reactor.

Microwave-induced synthesis and characterization of nanometer Ce_(0.5)Zr_(0.5)O_2 solid solution for the acidic catalytic reaction

Ce0.5Zr0.5O2 solid solution was successfully synthesized using cerium nitrate, zirconium nitrate, and urea as raw materials by the microwave irradiation method and characterized by X-ray diffraction, fluorescence spectrum, transmission electron microscopy, and infrared spectrum. Its acid catalytic activity was evaluated in the esterification reaction of acetic acid and n-butyl alcohol. The results show that Ce0.5Zr0.5O2 solid solution has cubic fluorite structure, and its particle diameter is in the nanometer scale. As a sort of solid acid, it possesses a higher acid catalytic activity and can be easily separated from reaction liquids. It can be used for several times, and basically, its activity keeps constant. The proton acid sites and Lewis acid sites exist in the structure of Ce0.5Zr0.5O2 solid solution.

Process intensification in gas/liquid/solid reaction in trickle bed reactors: A review

As an important form of reactors for gas/liquid/solid catalytic reaction,trickle bed reactors (TBRs) are widely applied in petroleum industry,biochemical,fine chemical and pharmaceutical industries because of their flexibility,simplicity of operation and high throughput.However,TBRs also show inefficient production and hot pots caused by non-uniform fluid distribution and incomplete wetting of the catalyst,which limit their further application in chemical industry.Also,process intensification in TBRs is necessary as the decrease in quality of processed crude oil,caused by increased exploitation depths,and more restrictive environmental regulations and emission standards for industry,caused by increased environment protection consciousness.In recent years,lots of strategies for process intensification in TBRs have been proposed to improve reaction performance to meet the current and future demands of chemical industry from the environmental and economic perspective.This article summarizes the recent progress in techniques for intensifying gas/liquid/solid reaction in TBRs and application of intensified TBRs in petroleum industry.

Kinetics of catalytically activated duplication in aggregation growth

We propose a catalytically activated duplication model to mimic the coagulation and duplication of the DNA polymer system under the catalysis of the primer RNA. In the model, two aggregates of the same species can coagulate themselves and a DNA aggregate of any size can yield a new monomer or double itself with the help of RNA aggregates. By employing the mean-field rate equation approach we analytically investigate the evolution behaviour of the system. For the system with catalysis-driven monomer duplications, the aggregate size distribution of DNA polymers αk（t） always follows a power law in size in the long-time limit, and it decreases with time or approaches a time-independent steady-state form in the case of the duplication rate independent of the size of the mother aggregates, while it increases with time increasing in the case of the duplication rate proportional to the size of the mother aggregates. For the system with complete catalysis-driven duplications, the aggregate size distribution αk（t） approaches a generalized or modified scaling form.

Preparation of new sunscreen materials Ce_(1-x)Zn_xO_(2-x) via solid-state reaction at room temperature and study on their properties

Superfine cerium-zinc oxides Ce1-xZnxO2-x with x = 0, 0.1, 0.3, 0.5, and 1.0 were obtained by grinding Ce（SO4）2·4H2O, ZnSO4·7H2O and NH4HCO3 under the condition of surfactant PEG-400 being present at room temperature, washing the mixture with water to remove soluble inorganic salts, drying at 80°C, and calcining.The precursor and its calcined samples were characterized using thermogravimetry and differential thermal analyses（TG/DTA）, UV-vis absorption spectroscopy, X-ray powder diffraction（XRD）, and scanning electron microscopy（SEM）.The results showed that superfine Ce1-xZnxO2-x behaved as an excellent UV-shielding material.The ZnO-doped CeO2 can facilitate the formation of crystalline state CeO2.The catalytic ability of products used in air oxidation of castor oil was investigated.The results showed that the catalytic abilities of products decreased with increasing zinc amount.

HOMOGENEOUS CATALYTIC REACTION(EC')AT GENERATION/COLLECTION MICROELECIRODE

A new type of macro-micro-macro triple electrode is fabricated. The kinetic equation is obtained by using the decrease in collection current to determine the kinetic constant of homogeneous catalytic reaction, the method can be used to study homogeneous chemical reaction with any magnitude of kinetic constant, and overcomes the disadvantages that the microelectrode is only suitable for fast catalytic reaction.

Evolution behavior of catalytically activated replication-decline in a coagulation process

We propose a catalytically activated replication-decline model of three species, in which two aggregates of the same species can coagulate themselves, an A aggregate of any size can replicate itself with the help of B aggregates, and the decline of A aggregate occurs under the catalysis of C aggregates. By means of mean-field rate equations, we derive the asymptotic solutions of the aggregate size distribution ak（t） of species A, which is found to depend strongly on the competition among three mechanisms： the self-coagulation of species A, the replication of species A catalyzed by species B, and the decline of species A catalyzed by species C. When the self-coagulation of species A dominates the system, the aggregate size distribution a^（t） satisfies the conventional scaling form. When the catalyzed replication process dominates the system, ak（t） takes the generalized scaling form. When the catalyzed decline process dominates the system, ak（t） approaches the modified scaling form.

Kinetics of catalytically activated aggregation-fragmentation process

We propose a catalytically activated aggregation-fragmentation model of three species, in which two clusters of species A can coagulate into a larger one under the catalysis of B clusters; otherwise, one cluster of species A will fragment into two smaller clusters under the catalysis of C clusters. By means of mean-field rate equations, we derive the asymptotic solutions of the cluster-mass distributions ak（t） of species A, which is found to depend strongly on the competition between the catalyzed aggregation process and the catalyzed fragmentation process. When the catalyzed aggregation process dominates the system, the cluster-mass distribution ak（t） satisfies the conventional scaling form. When the catalyzed fragmentation process dominates the system, the scaling description of ak （t） breaks down completely and the monodisperse initial condition of species A would not be changed in the long-time limit. In the marginal case when the effects of catalyzed aggregation and catalyzed fragmentation counteract each other, ak（t） takes the modified scaling form and the system can eventually evolve to a steady state.

CATALYTIC COLOR REACTION OF THE SYSTEM OF MIMETIC PEROXIDASE(Fe-T(3MPy)P)-LEUCO CRYSTAL VIOLET-HYDROGEN PEROXIDE

The mimetic peroxidase iron-tetrakis(3-N-methylpyridyl)- porphyrin (Fe-T(3MPy)P)can be used as a catalyst in the spectrophoto- metric determination of H_2O_2 and glucose.The method is based on the formation of crystal violet from leuco crystal violet.The glucose in human serum is determined by this reaction combined with catalytic reaction of glucose oxidase.

Stodies on the Witting Reaction (Ⅹ Ⅹ Ⅻ) Phase Transfer Catalytic Bis-Witting Reaction of 1,2-and 1,3-Bisylide

The phase transfer catalytic (PTC) bis-Wittig reaction between substitutedbenzaldehyde and 1,2- and 1,3-bisylides in the presence of K2Co3 was discussed.

THE SYNTHESES OF POLYQUINOLINES WITH 2,2'-PYRIDYLQUINOLINE AND 2,6-DIQUINOLYLPYRIDINE AS LIGAND AND THEIR APPLICATIONS IN SOME CATALYTIC REACTIONS

The polyquinolines with 2,2'-pyridylquinoline as bidentate and 2,6-diquinolylpyridine as tridentate ligand have been prepared from 4,4-dlamino- 3,3'-dibenzoyldiphenyl ether, 4,4'-diacetyldiphenyl ether and 1,4-bis (2-acetylpyridyl-6-oxy) benzene, 2,6-diacetylpyridine, respectively. These polyquinoline-supported ligands have been used in hydrogenation and hydroformylation of olefins with some transition metal complexes.

Effect of CeO_(2) nanoparticle sizes on catalytic performances of sulfated CeO_(2)/Al_(2)O_(3) catalyst in NH_(3)-SCR reaction

The sulfated CeO_(2)/Al_(2)O_(3) catalysts with different sizes of CeO_(2)nanoparticles were prepared by using pure H_2O or acetic acid solution as impregnation solvent, and the influence of sizes of CeO_(2) nanoparticles on the catalytic performances of the sulfated CeO_(2)/Al_(2)O_(3) catalyst was studied. The catalytic performance tests show that the sulfated CeO_(2)/Al_(2)O_(3) catalyst using acetic acid solution as impregnation solvent has better catalytic activity and the resistance to K+poisoning than the sulfated CeO_(2)/Al_(2)O_(3) catalyst using pure H_(2)O as impregnation solvent. The excellent catalytic performances can be ascribed to the smaller sizes of CeO_(2) nanoparticles in CeO_(2)/Al_(2)O_(3) catalyst using acetic acid solution, which results in larger amount of adsorbed sulfate species, surface acid sites, surface active oxygen species and excellent redox property. These features are helpful for improving the catalytic performances of sulfated CeO_(2)/Al_(2)O_(3) catalyst using smaller amount of CeO_(2) to cut the costs.

Photothermal Catalytic Selective Oxidation of Isobutane to Methacrylic Acid over Keggin-Type Heteropolyacid

Thermal and photothermal catalytic selec-tive oxidation of isobutane to methacrylic acid(MAA)are comparatively studied over a keggin-type Cs2.9Cu0.34V0.49PMo12O40 het-eropolyacid acid.An introduction of light was observed to enhance both the i-C4H10 conversion and the MAA selectivity,and consequently the MAA formate rate,particularly at low temperatures.Characterization re-sults show that oxidation of methacrolein(MAL)to MAA is the rate-limiting step while UV light illumination promotes the oxidation ofσ-bonded MAL with OH groups toσ-bonded MAA on the catalyst surface.These results demonstrate a synergistic effect of thermal cataly-sis and photocatalysis in selective oxidation of isobutane to MAA,which suggests photother-mal catalysis as a promising strategy to catalyze the selective oxidation of higher hydrocar-bons at relative mild reaction conditions.