High-performance liquid-phase catalytic purification of phosphine in tail gas using Pd(Ⅱ)/Cu(Ⅱ)composite

Pd/Cu liquid-phase composite was utilized as the catalyst in this study to remove PH_(3) at low temperatures.The anti-heterotoxicity of catalysts in the PH_(3) catalytic oxidation purification process was carefully explored and pioneered.The catalytic performance,thermodynamics,kinetics,and catalytic oxidation mechanism of Pd/Cu liquid-phase catalyst catalytic oxidation of PH_(3) were thoroughly investigated.The results showed that Pd/Cu has a superior catalytic effect on the removal of PH_(3) in the gas mixture under low temperature.With CO as the carrier gas,the removal efficiency of PH_(3) could be maintained at 100%for nearly 450 min,indicating that the Pd/Cu liquid phase catalyst has good resistance to heterotoxicity.According to the thermodynamic,kinetic,and related characterization results of the PH_(3) purification process,the kinetic region of the gas–liquid reaction of PH_(3) absorption by Pd/Cu solution was an interfacial reaction.Pd was the primary catalyst and Cu was the secondary catalyst,and the adsorption of PH_(3)was a primary reaction.PH_(3) was spontaneously oxidized to H_(3)PO_(4) in the Pd/Cu catalytic system during the removal process.Pd was regenerated by O_(2) and Cu,increasing the activity and stability of the Pd/Cu catalyst in the sustain and efficient purification of PH_(3) in tail gas.

Pt nanoparticles entrapped in ordered mesoporous carbons:An efficient catalyst for the liquid-phase hydrogenation of nitrobenzene and its derivatives

Pt nanoparticles entrapped in ordered mesoporous CMK-3 carbons with p6mm symmetry were prepared using a facile impregnation method, and the resulting materials were characterized using X-ray diffraction spectroscopy, N2 adsorption-desorption, scanning electron microscopy, transmission electron microscopy, energy dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy. The Pt nanoparticles were highly dispersed in the CMK-3 with 43.7% dispersion. The Pt/CMK-3 catalyst was an effective catalyst for the liquid-phase hydrogenation of nitrobenzene and its derivatives under the experimental conditions studied here. The Pt/CMK-3 catalyst was more active than commercial Pt/C catalyst in most cases. A highest turnover frequency of 43.8 s-1 was measured when the Pt/CMK-3 catalyst was applied for the hydrogenation of 2-methyl-nitrobenzene in ethanol under optimal conditions. It is worthy of note that the Pt/CMK-3 catalyst could be recycled easily, and could be reused at least fourteen times without any loss in activity or selectivity for the hydrogenation of nitrobenzene in ethanol.

Influences of the [Co^2＋]/[Co^3＋] Ratio on the Process of Liquid-phase Oxidation of Toluene by Air

Liquid phase oxidation of toluene is an environmental benign route for the production of benzoic acid.In a φ48mm bubble column reactor,the commercial process of toluene liquid phase oxidation was conducted with Co(CH3COO)2.4H2O as catalyst.The Co2+ concentration [Co2+] was determined by extraction spectrophotometry and hereby the Co3+ concentration [Co3+] was obtained by mass balance.The results showed that [Co3+] reached the maximum at about 25-30min.[Co3+] increased with increasing Co catalyst amount at total Co concentration<150 mg.L-1 of toluene.The conversion of toluene,yield and selectivity of benzoic acid increased with the increasing [Co3+/Co2+] max.A high [Co3+] and a high [Co3+]/[Co2+] ratio are beneficial to the reaction.

Kinetics of Liquid-Phase Hydrogenation of Toluene Catalyzed by Hydrogen Storage Alloy MlNi_5

The kinetics of liquid-phase hydrogenation of toluene catalyzed by MlNi_5 was studied by investigating the influences of the reaction temperature and pressure on the mass transfer-reaction processes inside the slurry. The results show that the reaction rate accelerates when the reaction temperature increases, and reaches its maximum at about 490 K, but if temperature is higher than 510 K, the reaction rate decreases rapidly. The whole reaction process is controlled by the reaction at the surface of the catalyst particles. The mass transfer resistance at gas-liquid interface and that from the bulk liquid phase to the surface of the catalyst particle can be neglected. The apparent reaction rate is zero order for toluene concentration and first order for hydrogen concentration in the liquid phase. The kinetic model is obtained. The kinetic model fits the experimental data very well. The apparent activation energy of the hydrogen absorption reaction of MlNi_5-toluene slurry system is 41.01 kJ·mol^(-1).

On the liquid-phase technology of carbon fiber/aluminum matrix composites

The main problems with the liquid-phase technology of carbon fiber/aluminum matrix composites include poor wetting of the fiber with liquid aluminum and formation of aluminum carbide on the fibers’surface.This paper aims to solve these problems.The theoretical and experimental dependence of porosity on the applied pressure were determined.The possibility of obtaining a carbon fiber/aluminum matrix composite wire with a strength value of about 1500 MPa was shown.The correlation among the strength of the carbon fiber reinforced aluminum matrix composite,the fracture surface,and the degradation of the carbon fiber surface was discussed.

Studies on the structure and catalytic performance of Cu-Zn-Al catalyst prepared by liquid-phase preparation technology under different heat treatment atmosphere

Cu-Zn-Al slurry catalysts were prepared using a complete liquid-phase preparation technology under different heat treatment atmospheres.The catalysts were characterized using X-ray diffraction,X-ray photoelectron spectroscope,and N2 adsorption-desorption.Their application in the single-step synthesis of dimethyl ether from syngas was also investigated.The results indicate that the type of heat treatment atmosphere has an influence on the Cu species and the Cu0/Cu＋ ratio on the catalyst surface.Moreover,the final Cu/Zn ratio on the catalyst surface is mainly dependent on the composition and reaction environment of the catalyst and less on the type of heat treatment atmosphere.The prepared catalysts can suppress sintering of active sites at high temperatures,and the type of heat treatment atmosphere mainly affects the capability of the catalyst for methanol synthesis.The catalysts perform best using N2 as the heat treatment atmosphere.

Kinetic Study on Liquid-Phase Hydrodesulfurization of FCC Diesel in Tubular Reactors

According to the characteristics of FCC diesel, a technology of liquid-phase hydrodesulfurization of the diesel in tubular reactors was proposed and lab-scale experiments were carried out. A kinetic model for the hydrodesulfurization process was developed and verified. The model was utilized to predict the sulfur content of products under different operating conditions. The effects of temperature, space velocity, pressure, and hydrogen concentration on the dcsulfurization rate were investigated.

Liquid-phase preparation and electrochemical property of LiFePO_4/C nanowires

Olivine LiFePO4/C nanowires have been successfully synthesized by a simple and eco-friendly solution preparation.The phase,structure,morphology and composition of the as-prepared products were characterized by powder X-ray diffraction(XRD),scanning electron microscopy(SEM),thermogravimetric and differential-thermogravimetric analysis(TG-DTA) and energy dispersive X-ray spectrometry(EDS) techniques,showing uniform nanowire shape of LiFePO4/C with a diameter of 80-150 nm and a length of several microns.The heat-treated LiFePO4/C nanowires show excellent electrochemical properties of specific discharge capacity,rate capacity and cycling stability.In particular,the LiFePO4/C nanowires heat-treated at 400 °C show preferable first discharge specific capacity of 161 mA·h/g at 0.1C rate,while the voltage platform is 3.4 V and the first discharge specific capacity is 93 mA·h/g at 20C rate.The specific capacity retention is 98% after 50 cycles at 5C rate.

Interfacial reactions and diffusion path in partial transient liquid-phase bonding of Si_3N_4/Ti/Ni/Ti/Si_3N_4

The interfacial reactions in partial transient liquid-phase bonding of Si3N4 ceramics with Ti/Ni/Ti interlayers were studied by means of scanning electron microscopy （SEM）, energy dispersive spectrometry （EDS） and X-ray diffractometry （XRD）. It was shown that the interfacial structure of Si3N4/TiN/Ti5Si3+Ti5Si4 + Ni3Si/ （NiTi ） /Ni3Ti/ Ni was formed after bonding. The activation energies for TiN layer and the mixed reaction layer of Ti5Si3 + Ti5Si4 + Ni3Si are 546. 8 kJ/mol and 543. 9 kJ/mol, respectively. The formation and transition processes of interface layer sequence in the joint were clarified by diffusion path. An important characteristic, which is different from the conventional brazing and soid-state diffusion bonding, has been found, i. e., during the partial transient liquid-phase bonding, not only the reaction layers which have formed grow, but also the diffusion path in the subsequent reaction changes because of the remarkable variation of the concentration on the metal side.

Microstructure and mechanical properties of 8YSZ ceramics by liquid-phase sintering with CuO-TiO_2 addition

The 8% （mass fraction） yttrium-partially-stabilized zirconia （8YSZ） ceramic was fabricated via liquid phase sintering at 1 200-1 400℃ by adding different mass ratios of CuO-16.7%TiO2 （molar fraction） as sintering aid. Relative density, microstructure, Vickers hardness and bending strength as a function of sintering temperature and additive content were investigated. The experiment results show that liquid phase sintering at low temperature can be realized through adding CUO-16.7% TiO2 to 8YSZ. The Vickers hardness and bending strength of samples with sintering aid are generally much higher than those of samples without sintering aid for all sintering temperatures, and increase with the increase of sintering temperature. When the addition content of CUO-16.7% TiO2 is beyond 0.5%, the relative density, Vickers hardness and bending strength decrease with the increase of the mass ratio of sintering aid. Low additions of sintering aid are beneficial to aiding densification; high additions of sintering aid are detrimental to the sintered properties mainly due to greater amounts of pores generated by the volatilization of oxygen with the eutectic reaction between copper oxide and titanium dioxide. It is found that the fine grain size and high relative density are two main reasons of the high bending strength and Vickers hardness of the materials.

Poly(ethylene glycol)-supported Liquid-phase Parallel Synthesis of Di(aryloxyacetyl)thiosemicarbazides

An efficient poly(ethylene glycol) (PEG)-supported liquid-phase parallel approach to di(aryloxyacetyl)thiosemicarbazides is described. PEG-bound phenol reacted with chloroacetic acid to afford PEG-bound phenyloxyacetic acid, which was readily converted into corresponding phenyloxyacetyl chloride. Subsequent nucleophilic substitution with ammonium thiocyanate followed by addition of aryloxyacetic acid hydrazides gave PEG-bound di(aryloxyacetyl)thiosemi-carbazides, which were easily cleaved to give the resulting library of 1-aryloxyacetyl-4-(4'-methoxylcarbonylphenyloxyacetyl)thiosemicarbazides in good to high yield and high purity.

Study on Liquid-Phase Axial Dispersion in Converging Taper Liquid-Solid Fluidized Beds

It is found analytically that the parabolic radial profile of liquid velocity in cylindrical liquid-solid fluidized bed (LSFB) causes particles to circulate around some radial position. This is the main reason for liquid-phase axial dispersions. The liquid-phase axial dispersion is depressed as the liquid velocity presents a flatter Bessel radial profile in a converging taper LSFB. The void fraction increases with axial distance in converging taper LSFB. The behavior produces less liquid-phase axial dispersion. Experimental results show good coincidence.

Computational Fluid Dynamics Simulation of Liquid-Phase FCC Diesel Hydrotreating in Tubular Reactor

The computational fluid dynamics(CFD) code, FLUENT, was used to simulate the liquid-phase FCC diesel hydrotreating tubular reactor with a ceramic membrane tube dispenser. The chemical reaction and reaction heat were added to the model by user-defined function(UDF), showing the distribution of temperature and content of sulfides, nitrides, bicyclic aromatics and monocyclic aromatics in different parts of the reaction bed. When the pressure was 6.5 MPa, the amount of mixing hydrogen was 0.84%(m), the space velocity was 2 h-1 and the inlet temperature was 633 K, the temperature reached a maximum at a height of 0.15 m, and the range of radial temperature reached its maximum(2.5 K) at a height of 0.15 m. It indicated that the proper ratio of height to diameter of catalyst bed in the tubular reactor was 5-6. The increase of inlet temperature, the mixing hydrogen and the decrease of space velocity led to the decrease in the content of bicyclic aromatics, sulfides and nitrides, and the increase in monocyclic aromatics content, while the high temperature increased. The results were in good agreement with experimental data, indicating to the high accuracy of the model.

Liquid-phase and solid-phase microwave irradiations for reduction of graphite oxide

In this paper, two microwave irradiation methods：（i） liquid-phase microwave irradiation（MWI） reduction of graphite oxide suspension dissolved in de-ionized water and N, N-dimethylformamide, respectively, and（ii） solid-phase MWI reduction of graphite oxide powder have been successfully carried out to reduce graphite oxide. The reduced graphene oxide products are thoroughly characterized by scanning electron microscopy, atomic force microscopy, X-ray photoelectron spectroscopy, Fourier transform infrared spectral analysis, Raman spectroscopy, UV-Vis absorption spectral analysis,and four-point probe conductivity measurements. The results show that both methods can efficiently remove the oxygencontaining functional groups attached to the graphite layers, though the solid-phase MWI reduction method can obtain far more efficiently a higher quality-reduced graphene oxide with fewer defects. The I（D）/I（G） ratio of the solid-phase MWI sample is as low as 0.46, which is only half of that of the liquid-phase MWI samples. The electrical conductivity of the reduced graphene oxide by the solid method reaches 747.9 S/m, which is about 25 times higher than that made by the liquid-phase method.

Mineral-phase evolution and sintering behavior of MO–SiO_2–Al_2O_3–B_2O_3 (M = Ca,Ba) glass-ceramics by low-temperature liquid-phase sintering

In this work, network former SiO_2 and network intermediate Al_2O_3 were introduced into typical low-melting binary compositions CaO·B_2O_3, CaO·2B_2O_3, and BaO·B_2O_3 via an aqueous solid-state suspension milling route. Accordingly, multiple-phase aluminosilicate glass-ceramics were directly obtained via liquid-phase sintering at temperatures below 950°C. On the basis of liquid-phase sintering theory, mineral-phase evolutions and glass-phase formations were systematically investigated in a wide MO–SiO_2–Al_2O_3–B_2O_3(M = Ca, Ba) composition range. The results indicate that major mineral phases of the aluminosilicate glass-ceramics are Al_(20)B_4O_(36), CaAl_2Si_2O_8, and BaAl_2Si_2O_8 and that the glass-ceramic materials are characterized by dense microstructures and excellent dielectric properties.

Polyethylene Glycol as Support and Phase Transfer Catalyst in Aqueous Palladium-catalyzed Liquid-phase Synthesis

Excellent yields and purity were obtained in the aqueous medium Suzuki, Sonogashira, Stille and Heck reactions using palladium (II) as catalyst in liquid phase synthesis. Polyethylene glycol (PEG) acted as soluble polymeric support and phase transfer catalyst as well.

Two-dimensional polyaniline nanosheets via liquid-phase exfoliation

Two-dimensional（2D） organic nanomaterials are fascinating because of their unique properties and pentential applications in future optoelectronic devices.Polyaniline（PANI） has attracted much attention for its high conductivity,good environmental stability and unusual doping chemistry.We report on liquid-phase exfoliation of layered PANI films grown by electrochemical polymerization.Atomic force microscopy images demonstrate that few-or even mono-layer PANI nanosheets can be fabricated.The PANI nanosheets can be transferred onto a variety of surfaces,providing a promising route to their incorporation into a variety of devices for further studies and various applications.

Nanobubble Dynamics in Aqueous Surfactant Solutions Studied by Liquid-Phase Transmission Electron Microscopy

Nanobubbles have attracted considerable attention in various industrial applications due to their exceptionally long lifetime and their potential as carriers at the nanoscale.The stability and physiochemical properties of nanobubbles are highly sensitive to the presence of surfactants that can lower their surface tension or improve their electrostatic stabilization.Herein,we report real-time observations of the dynamic behaviors of nanobubbles in the presence of soluble surfactants.Using liquid-phase transmission electron microscopy(TEM)with multi-chamber graphene liquid cells,bulk nanobubbles and surface nanobubbles were observed in the same imaging condition.Our direct observations of nanobubbles indicate that stable gas transport frequently occurs without interfaces merging,while a narrow distance is maintained between the interfaces of interacting surfactant-laden nanobubbles.Our results also elucidate that the interface curvature of nanobubbles is an important factor that determines their interfacial stability.

Combination of hollow fiber-based liquid-phase microextraction with sweeping techniques in micellar electrokinetic chromatography for the determination of Strychnos alkaloids in human urine

A new method for the enrichment of Strychnos alkaloids in biological samples via liquid-phase microextxaodon （LPME） based on porous polypropylene hollow fibers in combination with on-line sweeping in micellar electrokinodc chromatography was developed. The calibration curve was linear over the range of 20-200 ng mL^-1 for both strychnine and brucine in human urine sample. The detection limits （S/N = 3：1） for strychnine and brucine were 1 ng mL^-1 and 2 ng mL^-1, respectively. The LPME-sweeping method has been successfully applied to the analysis of strychnine and brucine in real urine samples.

Microstructural developments and precipitate transformation during transient liquid-phase bonding of a duplex stainless steel

Effect of holding time on microstructural developments and transformation of precipitates formed at the interface during transient liquid-phase bonding of a duplex stainless steel using a Ni-based amorphous insert alloy was studied. The experimental results reveal that the microstructure of the adjacent base metal varies clearly as a function of holding time. The migration of Cr and Ni elements and the → transformation seem to play relevant roles in this microstructure evolution. The scanning electron microscopy (SEM) and electron prob X-ray microanalysis (EPMA) results indicate the transformation of BN→BN and (N, Mo) boride→BN at the interface with the holding time of 60-1 800 s. N content changes with holding time increasing at locations at the interface might be a controlling factor contributing to this transformation.