Syntheses,crystal structures,and catalytic properties of three zinc(Ⅱ),cobalt(Ⅱ)and nickel(Ⅱ)coordination polymers constructed from 5⁃(4⁃carboxyphenoxy)nicotinic acid

Three zinc(Ⅱ),cobalt(Ⅱ),and nickel(Ⅱ)coordination polymers,namely[Zn(μ^(3-)cpna)(μ-dpea)_(0.5)]_(n)(1),[Co(μ^(3-)cpna)(μ-dpey)_(0.5)]_(n)(2),and[Ni(μ^(3-)cpna)(μ-dpey)_(0.5)(H_(2)O)]_(n)(3),have been constructed hydrothermally using H_(2)cpna(5-(4-carboxyphenoxy)nicotinic acid),dpea(1,2-di(4-pyridyl)ethane),dpey(1,2-di(4-pyridyl)ethylene),and zinc,cobalt,and nickel chlorides at 160℃.The products were isolated as stable crystalline solids and were characterized by IR spectra,elemental analyses,thermogravimetric analyses,and single-crystal X-ray diffraction analyses.Single-crystal X-ray diffraction analyses revealed that three compounds crystallize in the triclinic system,space group P1.Compounds 1-3 show 2D layer structures.The catalytic activities in the Knoevenagel condensation reaction of these compounds were investigated.Compounds 1 and 2 exhibit effective catalytic activities in the Knoevenagel condensa-tion reaction at room temperature.For this reaction,various parameters were optimized,followed by the investiga-tion of the substrate scope.CCDC:2335676,1;2335677,2;2335678,3.

Syntheses and catalytic performances of three coordination polymers with tetracarboxylate ligands

Three zincand cobaltcoordination polymers,namely{[Zn_(2)(μ_(6)-adip)(phen)_(2)]·4H_(2)O}_(n)(1),{[Co_(2)(μ_(6)-adip)(bipy)_(2)]·4H_(2)O}_(n)(2),and[Co_(2)(μ4-adip)(μ-bpa)_(2)]_(n)(3)have been constructed hydrothermally using H4adip(H4adip=5,5′-azanediyldiisophthalic acid),phen(phen=1,10-phenanthroline),bipy(bipy=2,2′-bipyridine),bpa(bpa=bis(4-pyridyl)amine),and zinc and cobalt chlorides at 160℃.The products were isolated as stable crystalline solids and were characterized by IR spectra,elemental analyses,thermogravimetric analyses,and single-crystal X-ray diffrac-tion analyses.Single-crystal X-ray diffraction analyses revealed that three compounds crystallize in the orthorhom-bic system Pnna(1 and 2)or P21212(3)space groups.All compounds exhibit 3D frameworks.The catalytic perfor-mances in the Henry reaction of these compounds were investigated.Compound 3 exhibited an effective catalytic activity in the Henry reaction at 70℃.CCDC:2339391,1;2339392,2;2339393,3.

CO_(2)-assisted oxidation dehydrogenation of light alkanes over metal-based heterogeneous catalysts

Light olefins are important platform feedstocks in the petrochemical industry,and the ongoing global economic development has driven sustained growth in demand for these compounds.The dehydrogenation of alkanes,derived from shale gas,serves as an alternative olefins production route.Concurrently,the target of realizing carbon neutrality promotes the comprehensive utilization of greenhouse gas.The integrated process of light alkanes dehydrogenation and carbon dioxide reduction(CO_(2)-ODH)can produce light olefins and realize resource utilization of CO_(2),which has gained wide popularity.With the introduction of CO_(2),coke deposition and metal reduction encountered in alkanes dehydrogenation reactions can be effectively suppressed.CO_(2)-assisted alkanes dehydrogenation can also reduce the risk of potential explosion hazard associated with O_(2)-oxidative dehydrogenation reactions.Recent investigations into various metal-based catalysts including mono-and bi-metallic alloys and oxides have displayed promising performances due to their unique properties.This paper provides the comprehensive review and critical analysis of advancements in the CO_(2)-assisted oxidative dehydrogenation of light alkanes(C2-C4)on metal-based catalysts developed in recent years.Moreover,it offers a comparative summary of the structural properties,catalytic activities,and reaction mechanisms over various active sites,providing valuable insights for the future design of dehydrogenation catalysts.

Electronic Communication Between Co and Ru Sites Decorated on Nitrogen-Doped Carbon Nanotubes Boosting the Alkaline Hydrogen Evolution Reaction

Designing highly efficient Pt-free electrocatalysts with low overpotential for an alkaline hydrogen evolution reaction(HER)remains a significant challenge.Here,a novel and efficient cobalt(Co),ruthenium(Ru)bimetallic electrocatalyst composed of CoRu nanoalloy decorated on the N-doped carbon nanotubes(CoRu@N-CNTs),was prepared by reacting fullerenol with melamine via hydrothermal treatment and followed by pyrolysis.Benefiting from the electronic communication between Co and Ru sites,the as-obtained CoRu@N-CNTs catalyst exhibited superior electrocatalytic HER activity.To deliver a current density of 10 mA·cm^(-2),it required an overpotential of merely 19 mV along with a Tafel slope of 26.19 mV·dec^(-1)in 1 mol·L^(-1)potassium hydroxide(KOH)solution,outperforming the benchmark Pt/C catalyst.The present work would pave a new way towards the design and construction of an efficient electrocatalyst for energy storage and conversion.

Hydrogen production performance of the non⁃platinum⁃based MoS_(2)/CuS cathode in microbial electrolytic cells

MoS_(2)/CuS composite catalysts were successfully synthesized using a one-step hydrothermal method with sodium molybdate dihydrate,thiourea,oxalic acid,and copper nitrate trihydrate as raw materials.The hydrogen pro-duction performance of MoS_(2)/CuS prepared with different molar ratios of Mo to Cu precursors(n_(Mo)∶n_(Cu))as cathodic catalysts was investigated in the two-chamber microbial electrolytic cell(MEC).X-ray diffraction(XRD),X-ray pho-toelectron spectroscopy(XPS),scanning electron microscopy(SEM),transmission electron microscope(TEM),linear scanning voltammetry(LSV),electrochemical impedance analysis(EIS),and cyclic voltammetry(CV)were used to characterize the synthesized catalysts for testing and analyzing the hydrogen-producing performance.The results showed that the hydrogen evolution performance of MoS_(2)/CuS-20%(nMo∶nCu=5∶1)was better than that of platinum(Pt)mesh,and the hydrogen production rate of MoS_(2)/CuS-20%as a cathode in MEC was(0.2031±0.0237)m^(3)_(H_(2))·m^(-3)·d^(-1) for 72 h at an applied voltage of 0.8 V,which was slightly higher than that of Pt mesh of(0.1886±0.0134)m^(3)_(H_(2))·m^(-3)·d^(-1).The addition of a certain amount of CuS not only regulates the electron transfer ability of MoS_(2) but also increases the density of active sites.

Depolymerization of Organosolv Lignin over Silica-alumina Catalysts

Efficient conversion of lignin to fine chemicals and biofuel become more and more attractive in biorefinery. In this work, we used a series of silica-alumina catalysts （i.e., SiO2-Al2O3, HY, Hβ, and HZSM-5） to degrade lignin into arenes and phenols. The relationship between the catalyst structure and lignin depolymerization performance was investigated. The results showed that both acidity and pore size of the catalyst could influence the conversion of lignin. In the volatilizable product, phenols were identified as the main phenolic monomers via gas chromatography-mass spectrometer. SIO2-Al2O3 was the most efficient catalyst, giving 90.96% degree of conversion, 12.91% yield of phenols, and 2.41% yield of arenes in ethanol at 280℃ for 4 h. The Fourier transform infrared spectroscopy and ^1H nuclear magnetic resonance spectroscopy analysis demonstrated that deoxygenation and alkylation occurred in this process. The effect of solvents was also investigated and the results showed that ethanol was the most efficient solvent.

Amine-grafted on lanthanide metal-organic frameworks:Three solid base catalysts for Knoevenagel condensation reaction

A post-synthetic modification strategy has been used to prepare three solid base catalysts, including Er（btc）（ED）075（H2O）0.25 （2, btc = 1,3,5-benzenetricarboxylates, ED = 1,2-ethanediamine）, Er（btc）（PP）0.55（H20）0.45 （3, PP = piperazine）, and Er（btc）（DABCO）0.15（H2O）0.85 （4, DABCO = 1,4- diazabicyclo[2.2.2]octane）, by grafting three different diamines onto the coordinatively unsaturated Er（III） ions into the channels of the desolvated lanthanide metal-organic framework （Er（otc））. The resulting metal-organic frameworks were characterized by elemental analysis, thermogravimetric analysis, powder X-ray diffraction, and N2 adsorption. Based on its higher loading ratio of the diamine, as well as its greater stability and porosity, catalyst 2 exhibited higher catalytic activity and reusability than catalysts 3 and 4- for the Knoevenagel condensation reaction. The catalytic mechanism of 2 has also been investigated using size-selective catalysis tests.

Coupled effect of cement hydration and temperature on rheological properties of fresh cemented tailings backfill slurry

The fluidity of fresh cemented tailings backfill（CTB） slurry depends on its rheological properties. Hence, it is crucial to understand the rheology of fresh CTB slurry, which is related to the cement hydration progress and temperature evolution within CTB mixtures. For this reason, a numerical model was developed to predict the evolution of the rheological properties of fresh CTB slurry under the coupled effect of cement hydration and temperature. Experiments were conducted to investigate the rheological behaviours of the fresh CTB slurry. By comparing the simulated results with the experimental ones, the availability of this developed model was validated. Thereafter, the model was used to demonstrate the coupled effect of cement hydration and temperature on the evolution of fresh CTB slurry＇s rheological properties, under various conditions（initial CTB temperature, cement to tailings ratio, and water to cement ratio）. The obtained results are helpful to better understanding the rheology of CTB slurry.

Multilayered Ti-Al intermetallic sheets fabricated by cold rolling and annealing of titanium and aluminum foils

Multilayered Ti-Al based intermetallic sheets were fabricated by sintering alternately layered titanium and aluminum foils.The microstructure and phase formation of the obtained sheets under different sintering conditions were evaluated by various techniques.The results reveal that when the sintering temperature is above the melting point of aluminum,the self-propagating high-temperature synthesis reaction occurs between Ti and Al,and forms various phases of Ti-based solid solutions including α-Ti Ti3Al,TiAl,TiAl2 and α-Ti including TiAl3,etc.When the sintering time increased,Ti-based solid solution,TiAl2 and TiAl3 disappeared gradually,and the sheet containing Ti3Al and TiAl phases in a multilayered structure formed finally.A lot of voids were also observed in the sintered structures,which were caused by the melting Al,Kirkendall effect and the difference of molar volumes between reactants and products.The voids were eliminated and a dense sample was obtained by the following hot press.

Environmentally benign and economic synthesis of covalent triazine-based frameworks

Covalent triazine-based frameworks（CTFs） are important microporous materials with a wide range of applications.Here,we demonstrate an environmentally benign and economic synthetic pathway to CTFs.The monomers used for CTFs,aromatic nitriles,were obtained by cyanation using nontoxic potassium hexacyanoferrate（Ⅱ） in place of commonly used toxic cyanides.Then,the CTFs were synthesized by trimerization of the corresponding cyano monomers in molten zinc chloride.A series of CTFs was synthesized,and the highest Brunauer-Emmett-Teller surface area measured in this series was 2404 m^2/g.Among the synthesized CTFs,CTF_（DCP） exhibited excellent CO_2 adsorption properties,with a CO_2 uptake of 225 mg/g at 0℃.

Rapid synthesis of Ti(C,N) powders by mechanical alloying and subsequent arc discharging

Ti（C,N） powders were synthesized by mechanical alloying （MA） from a mixture of pure titanium and graphite under a nitrogen atmosphere in a planetary mill.Effects of arc discharging on phase transformation and microstructure of MA powders milled for 1-7 h were explored.The results show that Ti（C,N） powders were prepared after mechanical milling for 1 h and subsequent arc discharge treatment,whereas the synthesis reaction did not occur in 7 h by mechanical milling alone.The ions produced during arc discharging interacted with powder particles and accelerated the diffusion of atoms and the nucleation on the surface of the as-milled powder,which results in fast synthesis of Ti（C,N） powders.The formation mechanisms of the two synthesis processes are self-propagating reactive synthesis.

Influence of freezing rate on microstructure and electrochemical properties of Mg-2%Ga alloys

Equilibrium freezing curve of Mg-2%Ga （mass fraction） alloy was calculated by CALPHALD method. Microstructures of the melted Mg-2%Ga alloys solidified by iron and copper moulds, respectively, were investigated using OM and SEM. Electrochemical properties of the Mg-2%Ga alloys with different freezing rates were measured by galvanostatic, potentiodynamic and electrochemical impedance spectroscopy tests. The results show that solidification by copper mould leads to intergranular MgsGa2 compounds with small size and large number density. Less adsorbent of Mg^＋ and oxide corrosion products occur on the surface of the Mg-2%Ga alloys solidified by copper mould, producing lower corrosion current density of 1.8×10^-5 mA/cm^2. In the galvanostatic tests with 100 mA/cm^2 current density, more negative stable potential of-1.604 V exists in the Mg-2%Ga alloys solidified by iron mould due to the lower freezing rate, which leads to smaller inductive and capacity time constants as well as shorter activity time and better electrochemical activity.

In-situ synthesis of Al_3Ti particles reinforced Al-based composite coating

Using titanium wires （99.5%, 200 μm in diameter） as a reactive source, an Al-based composite coating reinforced by titanium tri-aluminide （A13Ti） particles was fabricated by infiltration plus in-situ methods. According to the differential thermal analysis （DTA） curve, the reactive temperature between Ti wires and A1 matrix can be determined at 890 ℃. The obtained composite coatings were characterized by X-ray diffraction （XRD）, scanning electron microscopy （SEM）, and microhardness and wear test. The experimental results show that when holding period is 20 min at 890℃, the titanium wires react completely to in-situ synthesize Al3Ti particles, which presents blocky and strip-like states. The microhardness of in-situ synthesized Al3Ti particles is about 4.5 times that of the Al-matrix. Under the condition of dry sliding at 10 N load, compared with the unreinforced Al matrix, the composite coating fabricated with 20 min offers unique wear resistance behavior, and its wear mechanism is that the adhesive wear and abrasive wear coexist.

Synthesis of N,N'-bis(2,4-dinitrobenzofuroxan)-3,5-dinitro-2,6-diaminopyridine

N,N'-bis(2,4-dinitrobenzofuroxan)-3,5-dinitro-2,6-diaminopy- ridine has been synthesized from 2,6-diaminopyridine and trinitrodich- lorobenzene.For this compound,the structure has been determined by ele- mental analysis,IR,HNMR and MS spectroscopy.

Thermodynamic modelling and applications of Ce-La-O phase diagram

The Ce-La-O system was investigated via experiments and thermodynamic modeling. A series of CeO2-LaO1.5 mixtures were prepared by co-precipitation technique and examined by X-ray diffraction. Mutual solubilities between LaO1.5 and CeO2 at 1273 K were determined. Using the new experimental data together with literature information, a set of self-consistent thermodynamic parameters for the CeO2-LaO1.5 system were optimized. Combined with thermodynamic descriptions of Ce-O and La-O systems from literature, several property diagrams of Ce-La-O system were calculated and used to explain oxidation process of the Ce-La alloys. The fluorite phase is the unique oxidation products for most of the Ce-La alloys.

Optimization of reaction for synthesis of polyisobutylene amine between amination agent and epoxy polyisobutylene

An optimization study on the amination reaction of epoxy polyisobutylene for synthesis of polyisobutylene amine is presented. The experimental results indicate that n-butanol and ethylenediamine are the suitable solvent and amination agents for the reaction, respectively. The reaction yield of the amination reaction is notably increased with the enhanced molar ratio of either n-butanol against epoxy polyisobutylene or ethylenediamine against epoxy polyisobutylene. Also, the yield is enhanced with increasing temperature and time during the experimental range. Strikingly, the yield reaches as high as 91. 30% under optimal conditions; with the molar ratio of ethylenediamine, n-butanol and PIBO of 10∶ 6∶ 1, the reaction temperature of 150 ℃ and the reaction time of 6 h. In addition, the yield of the reaction is slightly decreased with the enhanced water content of the system. Accordingly, the mass concentration of water should be controlled within 1. 7% during the reaction.

Thermal nitridation of triazine motifs to heptazine-based carbon nitride frameworks for use in visible light photocatalysis

A thermal nitridation route for the assembly and polymerization of molecular triazine units to heptazine-based covalent frameworks has been successfully established. The obtained conjugated carbon nitride polymers feature nanostructures that show enhanced photocatalytic reactivity for hydrogen production under visible light irradiation.

EIS studies the effect of Zinc to Al-Zn alloy used for cathodic protection in 3% NaCl solution

Electrochemical impendence spectroscopy （EIS） is applied to investigate the dissolution behavior of Al-Zn alloys in 3% NaCl solution at different polarization potentials. A new reaction model is proposed, and the activation mechanism of zinc in Al-Zn alloys is achieved. There are three intermediates in the dissolution process： Znad^＋, Znad^2＋ and Alad^＋, ,of which only Zni can activate Al-Zn alloys. Most Znnd^＋ is produced by β-phase,and the alloys with 2. 3% - 3. 8% （wt） Zn dissolve rapidly. The Al-Zn alloys of heart-shaped EIS are active in 3% NaCl solution, thus EIS characteristic can be used to distinguish the activa-tion of Al-Zn alloys.

Hydrothermal synthesis of nanosized ZSM-22 and their use in the catalytic conversion of methanol

ZSM‐22 zeolite with different crystal lengths was prepared using a modified hydrothermal method. Rotation speed, Si/Al molar ratio and co‐solvent have important effects on the crystal size of ZSM‐22. The nanosized zeolite samples were characterized by X‐ray diffraction, X‐ray fluorescence, nitrogen adsorption, scanning electron microscopy, temperature‐programmed desorption of am‐monia and solid state nuclear magnetic resonance. The catalytic performance of nanosized ZSM‐22 was tested using the conversion of methanol. Compared to conventional ZSM‐22, the nanosized ZSM‐22 zeolite exhibited superior selectivity to ethylene and aromatics and lower selectivity to propylene. Stability against deactivation was clearly shown by the nanosized ZSM‐22 zeolite. A higher external surface area and smaller particle size make this nanosized ZSM‐22 zeolite attractive for catalytic applications.

Carbon supported IrM(M= Fe,Ni,Co) alloy nanoparticles for the catalysis of hydrogen oxidation in acidic and alkaline medium

We studied the alloying effect in lr-based alloys on the catalysis of the hydrogen oxidation reaction （HOP,） in both acidic and alkaline medium. IrFe, lrNi and IrCo alloy catalysts with nanoparticle size of 〈S nm were obtained by our solvent-vaporization plus hydrogen reduction method. The second metal played an important role in tuning the crystal structure and surface electronic structure of the Ir-based alloy catalyst. Among the lrFe, IrCo and lrNi alloy catalysts, Ni induced a mid-sized contrac- tion of the lr lattice, and gave the best HOR activity in both acidic and alkaline medium. In acidic medium, the weakening of the Ir-Had interaction caused by the electronic effect of M （M = Fe, Ni, Co） alloying is responsible for the enhancement of HOR activity. The oxophilic effect of the catalytic metal surface, which affects OHad adsorption and desorption and surface Had coverage, has a large impact on the HOR activity in the case of alkaline medium,