Different contents of fluoroethylene carbonate (FEC) as cosolvent is added into succinonitrile (SN) solution to form a novel electrolyte for lithium batteries. The SN-based electrolyte with 20 wt % FEC exhibits the most favorable properties involving the good thermal stability, wide electrochemical window and high ionic conductivity. Comparing with the commercial electrolyte, the 20% FEC-SN electrolyte demonstrates the advantage of high safety and excellent interfacial compatibility with lithium due to the form of compact and smooth solid electrolyte interphase layer on the anode. LiCoO2/Li cells using the SN-based electrolyte behave a high reversible discharge capacity of 122.4 mAh g–1 and keep an outstanding capacity retention of 91% (122.1 mAh g–1) at 0.5 C after 100 cycles at 25 °C, 50 °C, respectively. More importantly, the soft-package cells with the SN-based electrolyte can withstand harsh surroundings at 120 °C for 30 min without gas emitted, and can still keep the capacity retention of 77% compared to that before heat treatment, significantly higher than traditional commercial electrolyte (0%). All above results indicate the novel SN-based electrolyte can be an excellent alternative electrolyte in a practical lithium battery.Keywords: fluoroethylene carbonate; high temperature; interfacial compatibility; lithium battery; soft-package; succinonitrile;

A series of stators were designed with the same opening area but different opening shape and number for the inline single-row blade-screen high shear mixers (HSMs), to study the emulsification and extraction, respectively. The opening number has a significant influence on the emulsification and extraction, as compared to the opening shape. The computational fluid dynamics (CFD) analysis was used to disclose the intensifying rules of HSMs with desirable stator geometry. In the rotor and screen region, both energy dissipation rate and shear stress increase first but then decrease as the opening number rises, whereas in the jet region both of them decrease with the opening number. The opening number can affect the flux through screen and shear gap, as well as the reentrainment and jet behaviors in the screen region. These results provide important guidance on the design and optimization of HSMs structures to intensify the emulsification and extraction.

•The CFD simulation of the flow pattern for Newtonian and power-law fluids in HSMs.•Laminar and LES models were adopted respectively for laminar and turbulent regime.•Geometric parameters on flow pattern and power consumption were studied firstly.•A correlation of power consumption was built for in-line HSM.•The correlation considers the axial clearance and radical width.In-line high shear mixers (HSMs) with ultrafine teeth are useful to intensify mixing and dispersive process with viscous fluids. However, the relationships among the flow pattern, the power consumption and design parameters are not understood deeply yet, which hindered the further equipment optimization and scale-up. In this article, the effects of two important structural parameters, tip-to-base clearance and shear gap width, on flow pattern and power consumption of HSM were explored by CFD simulation. The LES and laminar model in turbulent and laminar flow regime were used respectively in CFD simulation with Newtonian and non-Newtonian fluids. The results indicate that with the increase of tip-to-base clearance and shear gap width, the velocity and strain rate in mixing head reduce significantly while the area of dead zone increased. The power number constant Kp and Ks of the standard in-line HSM predicted by CFD simulation agree well with the experimental data with acceptable error. The correlations of the predicted Kp and Ks of all designs which show their linear relationship with the tip-to-base clearance in axial direction f/(f + h) and power function with shear gap width in radial direction g/D. These results provide the guidance on process development and scale-up of in-line HSM with the ultrafine teeth for viscous fluids.

A series of catalysts with different ruthenium and chloride ratios were prepared and evaluated in the acetylene hydrochlorination reaction, in combination with several characterization techniques. The results indicate that the catalyst with the optimum ratio of Ru/Cl = 5/7 exhibits the highest initial acetylene conversion above 96.1% at 180 °C, an GHSV(C2H2) of 180 h−1, and a feed ratio VHCl/VC2H2 of 1.15. Appropriate coordination numbers of ruthenium and chloride could increase the amount of ruthenium oxides, improve the dispersion of Ru species on the carrier and enhance the adsorption ability of the catalyst, consequently improving the catalytic performance. TPPB additives can further enhance the activity and stability of the catalyst, which also provides a promising strategy to explore highly efficient and economic mercury-free catalysts for the hydrochlorination of acetylene.

•Ru10%[BMIM]BF4/AC catalyst exhibits high activity for acetylene hydrochlorination.•Ru10%[BMIM]BF4/AC catalyst has favorable anti-coking deposition property.•Ru species interact with [BMIM]BF4 and the oxygen-containing functional groups on the AC support.Imidazolium-based Ionic Liquids (IBILs) were employed to synthesize Ru-based catalysts using the Supported Ionic Liquid Phase (SILP) technique for acetylene (C2H2) hydrochlorination, combining the characterizations of transmission electron microscopy (TEM), N2 adsorption-desorption (BET), thermogravimetric analysis (TGA), temperature-programmed desorption (TPD), and X-ray photoelectron spectra (XPS), etc. The optimal Ru10%[BMIM]BF4/AC catalyst achieved the C2H2 conversion of 98.9% and the selectivity to vinyl chloride monomer (VCM) of 99.8% under the temperature of 170 °C and the C2H2 gas hourly space velocity (GHSV) of 180 h−1. Further, other IBILs with different anions were chosen to fabricate Ru-based catalysts, and the catalysts showed high activity and selectivity similar with Ru10%[BMIM]BF4/AC catalyst. It is demonstrated that IBILs additives can significantly improve the dispersion of ruthenium species and prevent the appearance of coke deposition owing to the interactions between Ru species and [BMIM]BF4. Moreover, the oxygen-containing functional groups on the carbon support are associated with the interactions among Ru species and [BMIM]BF4.Download full-size image

To prepare Ru-based catalysts with improved performance, activated carbon (AC) and Ru species were modified with nitric acid by different manners, and the resulting catalysts were characterized via a series of techniques. It was indicated that the oxidation of AC alone did not enhance the activity of the catalyst, but the modification enhanced the interaction between the oxygenated functional groups and Ru species, and the interaction could improve the catalytic performance of the catalysts. A Ru–O/AC–O catalyst prepared by the modification of active components, followed by the modification of AC exhibited outstanding activity and stability with an initial C2H2 conversion of 99.6% at 180 °C and a C2H2 space velocity of 180 h−1. The modification strengthened the adsorption of reactants, and also ensured the good dispersal of Ru species and augmented the amount of high-valence active species, consequently enhancing the catalytic activity.

To prepare Ru-based catalysts with improved performance, activated carbon (AC) and Ru species were modified with nitric acid by different manners, and the resulting catalysts were characterized via a series of techniques. It was indicated that the oxidation of AC alone did not enhance the activity of the catalyst, but the modification enhanced the interaction between the oxygenated functional groups and Ru species, and the interaction could improve the catalytic performance of the catalysts. A Ru–O/AC–O catalyst prepared by the modification of active components, followed by the modification of AC exhibited outstanding activity and stability with an initial C2H2 conversion of 99.6% at 180 °C and a C2H2 space velocity of 180 h−1. The modification strengthened the adsorption of reactants, and also ensured the good dispersal of Ru species and augmented the amount of high-valence active species, consequently enhancing the catalytic activity.

•The micromixing characteristics were investigated in inline high shear mixers.•The CFD modeling of HSM adopts the LES approach.•Adding a liquid distributor can intensify the micromixing of inline HSM system.•The micromixing time can reach 10−5 s using the dual rows ultrafine-teethed HSM.The micromixing performance of two inline high shear mixers (HSMs) was studied using the iodide-iodate reaction system, considering the effects of rotor speeds, flux ratios, viscosities and fluid concentrations. The segregation index (Xs) was adopted to assess the micromixing performance. It is indicated that the value of Xs decreases with the increase of rotor speed and the flux ratio of two feed solutions. The dual rows ultrafine-teethed HSM exhibits the poorer micromixing performance at low rotor speeds, comparing with the single-row blade-screen HSM. Then we modified the geometric configurations of the teethed HSM with the aid of computational fluid dynamics (CFD) analysis, including the modification of the clamp nut with blades and the addition of a liquid distributor, and reevaluated the micromixing performance in the modified HSM in order to improve mixing in the reactor. The results indicate that the fluid dispersion and turbulence intensity in the inlet region of the HSM play an important role in enhancing the micromixing level, the liquid distributor can greatly improve the micromixing performance of the dual rows ultrafine-teethed HSM and the estimated micromixing time can reach 10−5 s. The results obtained here will provide much insight for the applications of the inline HSMs and other reactors in the field of intensifying fast chemical reaction.Download high-res image (89KB)Download full-size image

A series of bimetallic PdAg catalysts on an activated carbon support were prepared and assessed for the direct synthesis of hydrogen peroxide from hydrogen and oxygen. The ensemble effect and electronic effect between Pd and Ag were characterized using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), temperature-programmed reduction (TPR), and temperature-programmed desorption of H2/O2 (H2-/O2-TPD), etc. Our results showed that the Ag additive increased the monomeric Pd sites which were the primary active sites for H2O2 formation. In addition, the content of Pd2+ was increased via the electronic interaction between Pd and Ag, which prevented the decomposition and hydrogenation of H2O2 to some extent. Therefore, the selectivity of this reaction was increased using bimetallic PdAg catalysts, as compared with the monometallic Pd catalyst. The optimal PdAg-40 catalyst achieved a H2O2 productivity of 7022 mol kgPd−1 h−1 and a high selectivity of 70.9%, which were superior to those of the Pd/C catalyst.

Bimetallic gold–strontium catalysts were prepared and assessed for the effect of a Sr(II) additive on the catalytic performance of gold-based catalysts for acetylene hydrochlorination, combined with characterization using N2 adsorption/desorption, thermogravimetric analysis, temperature-programmed reduction/desorption, powder X-ray diffraction, transmission electron microscopy, atomic absorption spectrophotometry and X-ray photoelectron spectroscopy. The optimal catalytic performance is obtained over an Au1Sr(II)1/AC catalyst with acetylene conversion of 87.7% and selectivity for VCM of 99.8%, after 20 h on stream under the conditions of a temperature of 180 °C, a C2H2 gas hourly space velocity (GHSV) of 762 h−1, and a feed volume ratio HCl/C2H2 of 1.15, which is an increase of 24.3% compared with acetylene conversion of 63.4% after 20 h on stream under the same conditions over a monometallic Au/AC catalyst. It is indicated that the addition of Sr(II) can disperse the Au species well and inhibit carbon deposition on the catalyst surface; the Sr(II) additive can enhance the adsorption of the two reactants, acetylene and hydrogen chloride, on the catalyst and inhibit the reduction of Au3+ to Au0 during the preparation and reaction, consequently enhancing the catalytic activity and long-term stability of gold-based catalysts.

A Ru-based catalyst (Ru/N-AC) was prepared using N-doped carbon as the support and the catalytic performance of the one-step synthesis reaction of vinyl chloride monomer (VCM) from acetylene and 1,2-dichloroethane (EDC) was assessed. It is indicated that 1% Ru/N-AC exhibited good catalytic activity with an initial acetylene conversion of 95.2% at 250 °C, an EDC total liquid hourly space velocity (LHSV) of 0.2 h−1 and a molar ratio n(EDC)/n(C2H2) of 1, much better than that of 1% Ru/AC or N-AC. Through BET, TG, XPS, ICP, TPR, TPD, TEM and XRD characterization, it is indicated that N-doped AC support can increase the amount of RuO2 and RuOx species in the catalyst and enhance its adsorption ability for both EDC and acetylene, suggesting that the N dopant and Ru species generated a synergistic effect in the one-step synthesis reaction of VCM.

Gold–cerium oxide catalysts were prepared to study the effects of cerium oxide additives on the catalytic performance of gold catalysts for acetylene hydrochlorination, using activated carbon as the support. The optimal catalytic performance is achieved over the 1Au–5CeO2/AC catalyst with an acetylene conversion of 98.4% and a selectivity to vinyl chloride monomer (VCM) of 99.9% after 20 h on stream under the conditions of 180 °C, C2H2 gas hourly space velocity (GHSV) of 852 h−1 and HCl/C2H2 feed volume ratio of 1.15. It is indicated that the addition of cerium oxide can make active Au species uniformly dispersed and improve the adsorption properties of reactants on the catalysts, but also suppress the reduction of active gold species and inhibit coke deposition on the catalyst surfaces during the reaction. Characterization was carried out using transmission electron microscopy, Raman spectroscopy, N2 adsorption/desorption analysis, thermogravimetric analysis, temperature-programmed reduction, temperature-programmed desorption, powder X-ray diffraction, atomic absorption spectroscopy and X-ray photoelectron spectroscopy.

As an advanced and new technology in molecular simulation fields, ReaxFF reactive force field has been developed and widely applied during the last two decades. ReaxFF bridges the gap between quantum chemistry (QC) and non-reactive empirical force field based molecular simulation methods, and aims to provide a transferable potential which can describe many chemical reactions with bond formation and breaking. This review presents an overview of the development and applications of ReaxFF reactive force field in the fields of reaction processes, biology and materials, including (1) the mechanism studies of organic reactions under extreme conditions (like high temperatures and pressures) related with high-energy materials, hydrocarbons and coals, (2) the structural properties of nanomaterials such as graphene oxides, carbon nanotubes, silicon nanowires and metal nanoparticles, (3) interfacial interactions of solid-solid, solid-liquid and biological/inorganic surfaces, (4) the catalytic mechanisms of many types of metals and metal oxides, and (5) electrochemical mechanisms of fuel cells and lithium batteries. The limitations and challenges of ReaxFF reactive force field are also mentioned in this review, which will shed light on its future applications to a wider range of chemical environments.

Bimetallic gold–barium catalysts were prepared and assessed for acetylene hydrochlorination, and characterized using low-temperature N2 adsorption/desorption, thermogravimetric analysis, X-ray diffraction, temperature-programmed reduction/desorption, inductively coupled plasma-atomic emission spectroscopy, transmission electron microscopy, and X-ray photoelectron spectroscopy. The best catalytic performance is obtained over Au1Ba(II)1/AC catalysts with the acetylene conversion of 98.4% and the selectivity to VCM of 99.9%. It is indicated that the addition of Ba(II) can make Au species disperse well and inhibit carbon deposition on the catalyst surface; Ba(II) additives can enhance the adsorption of reactants on the catalysts but also inhibit the reduction of active gold species during the reaction, consequently augmenting the activity and long-term stability of gold catalysts.

In this study, single-crystal Pd nanocrystals with exposed (100) and (111) facets were prepared and their catalytic performance were compared in 2-ethylanthraquinone hydrogenation reaction through immobilization on γ-Al2O3 as catalyst. Our experimental results combined with density functional theory calculations showed that the Pd (100) facet was more active than Pd (111) in CO hydrogenation but less active in saturation of aromatic rings. Directed by this result, a high-performance Pd/γ-Al2O3 nanocatalyst was successfully prepared using a one-step synthesis method, which could not only control the exposure of the Pd (100) facet but also increase the stability of Pd components. This catalyst exhibited superior catalytic performance with a hydrogenation efficiency of up to 15.0 g L−1 and a selectivity of 99.1% under mild reaction conditions (0.2 MPa, 50 °C, 15 min), which was superior to that of the catalyst prepared by an impregnation method.

The catalytic mechanism of Ru-based catalysts in the acetylene hydrochlorination reaction has been investigated via the density functional theory (DFT) method. To study the effect of the chlorine coordination number on the catalytic mechanism, Ru3Cl9, Ru3Cl7, Ru5Cl7, Ru3Cl3 and Ru3 clusters were chosen as the catalytic models. Our results show that the energy barrier for acetylene hydrochlorination on Ru3Cl9 was as high as 1.51 eV at 458 K. When the chlorine coordination number decreased, the energy barriers on Ru3Cl7, Ru5Cl7, Ru3Cl3 and Ru3 were 1.29, 0.89, 1.01 and 1.42 eV, respectively. On Ru3Cl9, the H and Cl atoms of HCl were simultaneously added to C2H2 to form C2H3Cl, while the reaction was divided into two steps on Ru3Cl7, Ru3Cl3 and Ru3 clusters. The first step was the addition of H atom of HCl to C2H2 to form C2H3˙, and the second step was the addition of Cl atom to C2H3˙ to form C2H3Cl. The step involving the addition of Cl was the rate-controlling step during the whole reaction. On Ru5Cl7 cluster, there was an additional step before the steps involving the addition of H and Cl: the transfer of H atom from HCl to Ru atom. This step was the rate-controlling step during the reaction of acetylene hydrochlorination on Ru5Cl7 and its energy barrier was the lowest among all the above-mentioned catalytic models. Therefore, the Ru5Cl7 cluster played the most predominant role in acetylene hydrochlorination with the largest reaction rate constant kTST of 103.

A series of N-doped coconut activated carbon catalysts (N-AC) were prepared using melamine as the nitrogen precursor and their performance for the catalytic dehydrochlorination of 1,2-dichloroethane (1,2-DCE) to produce vinyl chloride monomer (VCM) was assessed. It is indicated that the N-doped catalyst 5:10-N-AC exhibits a stable catalytic activity at 250 °C with the 1,2-DCE conversion of 85.1% at 180 h. Through DFT calculations, it is suggested that both pyridinic and pyrrolic nitrogen dopants can adsorb preferentially 1,2-DCE and increase the activity for 1,2-DCE dehydrochlorination at low temperature, in combination with characterizations of BET, Raman, TG, TPD, XPS, etc. In addition, the increase of quaternary nitrogen dopants and coking deposition on the catalyst surface can result in the activity decline. The N-doped activated carbon catalyst provides a promising pathway to produce VCM through a low-temperature energy-saving process of 1,2-DCE catalytic dehydrochlorination.

Heat exchanger network synthesis (HENS) is faced with the dilemma of substantial nonisothermal mixing and nonconstant thermal properties of streams against the higher computational efficiency required to solve mathematical programming models with a large amount of variables and high nonlinearity. In this work, by replacing the conventional binary variable in a HENS model, a nonlinear approximation term is developed to indicate the existence of a heat exchanger so as to reduce the amount of variables and constraint as well as enhance the model’s computational efficiency. With this approximation, a new HENS model was formulated considering simultaneously nonisothermal mixing and temperature-dependent heat capacity flow rate. All the variables of the model are stated with clear upper and lower bounds. A 10-stream (5 hot process streams and 5 cold process streams) benchmark HENS problem is solved by the developed model. The results show that the proposed model can generate a better cost-optimal heat exchanger network (HEN) with more accurate configuration in relatively short solution time compared with that in the literature.

To improve the activity and stability of Ru-based catalysts with a carbon support for acetylene hydrochlorination, activated carbon (AC) was consecutively modified by nitration, amination and pyridine, and the effect of the different carbon supports on the Ru-based catalysts for acetylene hydrochlorination was investigated. The results of the FT-IR studies confirmed that –NO2, –NH2 and –N–H–N groups were separately grafted onto the surface of the AC. Under the same reaction conditions, the modified catalysts exhibited better catalytic activity compared with the original Ru/AC catalyst. Moreover, the catalyst Ru/AC-NHN showed the best catalytic performance with a slight decrease after 48 h from 93.2% to 91.8%. The increase in catalytic activity indicates that the modification with nitrogen functional groups is beneficial for acetylene hydrochlorination.

Ru-based catalysts with different deposition sites were prepared using multiwalled carbon nanotubes as the support and RuCl3 as the precursor, to study the effects of multiwalled carbon nanotubes on the catalytic performance of Ru catalysts for acetylene hydrochlorination. It has been suggested that Ru catalysts deposited inside the CNTs channels exhibit the optimal catalytic activity with the acetylene conversion of 95.0% and the selectivity to VCM of 99.9% after 10 h on stream under the conditions of 170 °C and GHSV (C2H2) of 90 h−1. In combination with characterizations of BET, TEM, XRD, TPR, TPD and XPS, it is illustrated that the CNTs with the inner diameter about 3–7 nm can functionalize as an efficient support with unique electron property to enhance the catalytic performance of Ru-based catalysts for acetylene hydrochlorination.

In order to disclose the reason that the N-doped carbon support can enhance the stability of Au-based catalysts for acetylene hydrochlorination, we established a big graphene cluster model of C110H28 to investigate the effect of different nitrogen-doped carbon supports on three kinds of gold species models of Au dimers, Au2Cl2 and Au2Cl6, through DFT calculations. Comparing the adsorption energy of each Au complex and the transferred charge from the support to the Au complex, it is observed that on the N-doped support GRN-I (the pyridinic N-doped graphene) the adsorption energies of the Au dimer, Au2Cl2 and Au2Cl6, are much higher than those on other three kinds of supports, and the Au complex accepts most of the transferred charges from the support of GRN-I. The effect of different supports on the adsorption of C2H2 and HCl was studied on Au2Cl6/supports, suggesting that the co-adsorption of both reactants occurs on Au2Cl6/GRN-I. The results indicate that the N-doped support of GRN-I can stabilize the gold species Au2Cl6 and enhance the interaction between Au2Cl6 and HCl, which can inhibit the reduction of Au3+ and then increase the long-term stability of Au-based catalysts.

The mass transfer characteristics of a gas–liquid continuous flow system accompanied by reaction in two commercial inline high shear mixers (HSMs) were evaluated by the sulphite oxidation method. The gas–liquid specific interfacial area, a, and the volumetric mass transfer coefficient, kLa, were measured under different operating conditions involving the rotor speed, the liquid flow rate, the gas flow rate and the surface tension. The results indicate that a and kLa increase with the rotor speed and liquid flow rate due to an increase of turbulence intensity. Both parameters increase slightly first but then decrease with the gas flow rate. For either the dual rows ultrafine-toothed or the single-row blade-screen configuration of HSMs, a increases while kLa decreases with the surfactant concentration, and both of them tend to be changeless at the surfactant concentration higher than 30 mg/L. Correlations for the specific interfacial area and the Sherwood number are obtained to guide the process design and scale-up of both types of inline HSMs.

Several gold-based catalysts including Au, Au–La(III), Au–Co(II), and Au–Co(III) were prepared and assessed for acetylene hydrochlorination, combining with characterizations of low-temperature N2 adsorption/desorption, thermogravimetric analysis, X-ray diffraction, temperature-programmed reduction, inductively coupled plasma-atomic emission spectroscopy, transmission electron microscopy, and X-ray photoelectron spectroscopy. The best catalytic performance was obtained over Au1Co(III)3/SAC catalysts with an acetylene conversion of 92% and a selectivity to VCM of 99.9%. It is indicated that the additives of Co(III), Co(II) and La(III) are preferential to stabilize the catalytic active Au+ species and inhibit the reduction of Au3+ to Au0 in the preparation process of Au-based/SAC catalysts. The addition of these additives can greatly inhibit the occurrence of coke deposition on the catalyst surface, and also inhibit the catalyst sintering, thereby improving the activity and long-term stability of the Au-based catalysts.

Two main commercial in-line high shear mixer (HSM) configurations, including the dual rows ultrafine teethed and the single-row blade-screen in-line units, were investigated under the pump-fed mode in order to disclose the pump capacity and power consumption characteristics. Results indicate that the pump capacity of the teethed in-line HSM is rather poor, with maximum pumping heads of 2.31–2.72 m and a maximum pumping efficiency of 1.5%. By contrast, the blade-screen in-line HSM demonstrates maximum heads around 4.33–4.76 m and a maximum pumping efficiency of 7.3%. The power number data of both units with the bearing loss subtracted can be correlated by the Froude number modified power consumption model. The predicted power numbers show good agreement with the experimental data for both in-line HSMs. The results obtained here are fundamental for the performance assessment as well as the design and selection of in-line HSMs.

Single-pass continuous emulsifications were studied in kerosene– and silicone oil–aqueous systems with two inline high shear mixers (HSMs) adopting two main commercial configurations, including the dual-row ultrafine-toothed and the single-row blade–screen units. The effects of the processing parameters on the measured drop sizes and power consumptions were investigated. Bimodal drop size distributions (DSDs) were observed within both inline HSMs due to the inhomogeneity of the turbulence and shear levels accompanied with the recirculation and re-entrainment flow patterns. The drop sizes increase with increases in the dispersed-phase volume fraction and the continuous-phase flow rate and decrease with increases in the rotor speed and the continuous-phase viscosity. Correlations for the Sauter mean diameters were also obtained. The results obtained here are fundamental for the assessment of emulsification capability as well as the design and selection of inline HSMs.

First-principles density functional theory studies have been carried out to investigate the effects of perfect and defective anatase TiO2 supports on the structural stabilities and electronic properties of PdmAgn(m + n = 2–5) bimetallic clusters. Our results showed that the structures of supported Pd–Ag bimetallic clusters are distorted compared to their structures in the gas phase, which is caused by the balance of the cluster inner-interaction and the metal-support interfacial interaction. In particular, Pd1Ag3 and Pd1Ag4 clusters prefer to form three-dimensional structures on both perfect and defective anatase TiO2 support while their most stable structures in the gas phase are planar. In the most stable structures of supported PdmAgn bimetallic clusters, Pd atoms always occupy the most active sites of TiO2(101) surface, which induced Pd enriched at the interface of TiO2 support and Ag atoms exposed at the surface of the bimetallic cluster. As Ag% increases, the perfect TiO2 support gets more electrons from the Pd–Ag bimetallic cluster, which reduced the stability of the supported Pd–Ag cluster. The Mulliken population and electron density difference analysis demonstrated that the co-deposition of Ag induced the charge of adsorbed Pd on the perfect TiO2 support from positive to negative as a result of charge transfer from the half-filled s-orbital of Ag(5s1) to the d-orbit of Pd, and the negative charges of Pd on the defective TiO2 support were also increased by Pd–Ag charge polarization. Therefore, the selectivity of acetylene hydrogenation is enhanced by anatase-TiO2 supported Pd–Ag bimetallic catalyst as it serves as an electron donor.

Heat transfer coefficients were measured by immersed probes in co- and counter-current G–L–S magnetically stabilized fluidized beds (MSFBs) using air, water and nickel-alloy particles as the gas, liquid and solid phases. Influences of major factors, including magnetic field intensity, superficial gas and liquid velocities, liquid viscosity and surface tension, on heat-transfer properties were studied experimentally, indicating that both co- and counter-current G–L–S MSFB can provide relatively uniform radial distribution of heat transfer coefficients under appropriate operation conditions, thus controlling operation temperature for highly exothermic multi-phase reaction systems. Two correlations were provided to estimate accurately heat transfer properties in both co- and counter-current G–L–S MSFB systems, with an average error of less than 10%.The heat transfer coefficients were measured by immersed probes in co- and counter-current G–L–S magnetically stabilized fluidized beds (MSFBs). Using air, water and nickel-alloy particles as the gas, liquid and solid phases, the influences of major factors on heat-transfer properties were studied experimentally. Two equations were proposed for estimating accurately heat transfer properties in the G–L–S MSFB, with an average error of less than 10%.

Polyvinyl chloride (PVC) has become the third most used plastic after polyethylene and polypropylene and the worldwide demand continues to increase. Polyvinyl chloride is produced by polymerization of the vinyl chloride monomer (VCM), which is manufactured industrially via the dehydrochlorination of dichloroethane or the hydrochlorination of acetylene. Currently PVC production through the acetylene hydrochlorination method accounts for about 70% of the total PVC production capacity in China. However, the industrial production of VCM utilizes a mercuric chloride catalyst to promote the reaction of acetylene and hydrogen chloride. During the hydrochlorination, the highly toxic mercuric chloride tends to sublime, resulting in the deactivation of the catalyst and also in severe environmental pollution problems. Hence, for China, it is necessary to explore environmental friendly non-mercury catalysts for acetylene hydrochlorination as well as high efficiency novel reactors, with the aim of sustainable PVC production via the acetylene-based method. This paper presents a review of non-mercury heterogeneous and homogeneous catalysts as well as reactor designs, and recommends future work for developing cleaner processes to produce VCM over nonmercury catalysts with high activity and long stability.

•Liquid–liquid mass transfer were investigated first time in inline high shear mixers.•Partition coefficient of the benzoic acid between water and kerosene was determined by a linear relationship.•Mass transfer characteristics under different operation conditions were investigated.•Dimensionless Sherwood number was correlated with the experimental data.•Inline HSMs have superior liquid–liquid mass transfer performance and a great application prospect.The liquid–liquid mass transfer properties of two inline high shear mixers (HSMs) were investigated by the liquid–liquid extraction (LLE) method using the water-benzoic acid-kerosene system. The characteristic parameters of the extraction efficiency (E) and volumetric mass transfer coefficient (KLa) were measured under different conditions involving the rotor speed, two liquid phase flow rates, and surfactant concentration. The results indicate that both E and KLa increase with the rotor speed and aqueous-phase flow rate. The value of E decreases sharply but KLa increases slightly with the organic-phase flow rate. Both E and KLa increase first and then decrease with the surfactant concentrations. Dimensionless correlations for the Sherwood number were obtained to provide guidance on the optimization and scale-up design of these kinds of inline HSMs.

Ni-based catalysts doped with copper additives were studied on their role in ethanol steam reforming reaction. The effects of Cu content, support species involving Al2O3-SiO2, Al2O3-MgO, Al2O3-ZnO, and Al2O3-La2O3, on the catalytic performance were studied. Characterizations by TPR, XRD, NH3-TPD, XPS, and TGA indicated that catalysts 30Ni5Cu/Al2O3-MgO and 30Ni5Cu/Al2O3-ZnO have much higher H2 selectivity than 30Ni5Cu/Al2O3-SiO2, as well as good coke resistance. H2 selectivity for 30Ni5Cu/Al2O3-MgO catalyst was 73.3% at 450 °C and increased to 94.0% at 600 °C, whereas for 30Ni5Cu/Al2O3-ZnO catalyst, the H2 selectivity was 63.6% at 450 °C and 95.2% at 600 °C. These Al2O3-MgO and Al2O3-ZnO supported Ni-Cu bimetallic catalysts may have important applications in the production of hydrogen by ethanol steam reforming reactions.

Liquid–solid (L–S) mass transfer coefficients (Ks) were characterized in a gas–liquid–solid (G–L–S) three-phase countercurrent magnetically stabilized bed (MSB) using amorphous alloy SRNA-4 as the solid phase. Effects of superficial liquid velocity, superficial gas velocity, magnetic field strength, liquid viscosity and surface tension were investigated. Experimental results indicated that the external magnetic field increased Ks in three-phase MSB, as compared to those in conventional G–L–S fluidized beds; that Ks increased with magnetic field strength, superficial gas and liquid velocities and decreased with liquid viscosity and surface tension; and that Ks showed uniform axial and radial distributions except for small increases close to the wall. Dimensionless correlations were established to estimate Ks of the G–L–S countercurrent MSB using SRNA-4 catalyst, with an average error of 3.6%.

A series of Au–Sn/AC catalysts for acetylene hydrochlorination were prepared by an incipient wetness impregnation method and characterized by BET, XPS, TEM, TPR, XRD, ICP-AES and TPD techniques. It is indicated that Au1Sn1/AC catalyst shows the highest activity and stability with the 95% acetylene conversion after 48 h reaction under the conditions of 170 °C and an acetylene gas hourly space velocity of 720 h−1. The Sn additive can make the Au species dispersed well and weaken the occurrence of coke deposition, as well as inhibit the reduction of Au3+ to Au0, thereby improving the catalytic activity and stability.Download full-size image

The solubilities of dexibuprofen in five solvents including methanol, n-butyl alcohol, isobutyl alcohol, n-amyl alcohol, and n-octyl alcohol were measured in the temperature range 263.15–293.15 K under atmospheric pressure. The results indicate that the solubilities of dexibuprofen in the selected solvents increase with temperature. The experimental data were correlated by the modified Apelblat model which fit well with the experimental data. The dissolution enthalpy and entropy of both rac-ibuprofen and dexibuprofen were predicted. Moreover, the solubility data of both of them were correlated using two local composition models: NRTL 1 and UNIQUAC. It is indicated that for dexibuprofen, the NRTL 1 model can provide more accurate estimations of the solubility in the solvents of methanol, ethanol and n-propyl alcohol, while both NRTL 1 and UNIQUAC models can provide good estimations of the solubility in other solvents. For the rac-ibuprofen, the UNIQUAC model performs better to estimate the solubility in all the solvents.Highlights► We measured the solubility data and correlated them by the modified Apelblat model. ► The dissolution enthalpy and entropy of both rac-ibuprofen and dexibuprofen were predicted. ► The solubility data were correlated using NRTL 1 and UNIQUAC model. ► The ΔHd, ΔSd and ΔGd values were estimated and analyzed. ► We made the distinctions between the models for the (S)-enantiomer and the racemate.

A series of bimetallic PdAg catalysts on an activated carbon support were prepared and assessed for the direct synthesis of hydrogen peroxide from hydrogen and oxygen. The ensemble effect and electronic effect between Pd and Ag were characterized using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), temperature-programmed reduction (TPR), and temperature-programmed desorption of H2/O2 (H2-/O2-TPD), etc. Our results showed that the Ag additive increased the monomeric Pd sites which were the primary active sites for H2O2 formation. In addition, the content of Pd2+ was increased via the electronic interaction between Pd and Ag, which prevented the decomposition and hydrogenation of H2O2 to some extent. Therefore, the selectivity of this reaction was increased using bimetallic PdAg catalysts, as compared with the monometallic Pd catalyst. The optimal PdAg-40 catalyst achieved a H2O2 productivity of 7022 mol kgPd−1 h−1 and a high selectivity of 70.9%, which were superior to those of the Pd/C catalyst.

Bimetallic gold–strontium catalysts were prepared and assessed for the effect of a Sr(II) additive on the catalytic performance of gold-based catalysts for acetylene hydrochlorination, combined with characterization using N2 adsorption/desorption, thermogravimetric analysis, temperature-programmed reduction/desorption, powder X-ray diffraction, transmission electron microscopy, atomic absorption spectrophotometry and X-ray photoelectron spectroscopy. The optimal catalytic performance is obtained over an Au1Sr(II)1/AC catalyst with acetylene conversion of 87.7% and selectivity for VCM of 99.8%, after 20 h on stream under the conditions of a temperature of 180 °C, a C2H2 gas hourly space velocity (GHSV) of 762 h−1, and a feed volume ratio HCl/C2H2 of 1.15, which is an increase of 24.3% compared with acetylene conversion of 63.4% after 20 h on stream under the same conditions over a monometallic Au/AC catalyst. It is indicated that the addition of Sr(II) can disperse the Au species well and inhibit carbon deposition on the catalyst surface; the Sr(II) additive can enhance the adsorption of the two reactants, acetylene and hydrogen chloride, on the catalyst and inhibit the reduction of Au3+ to Au0 during the preparation and reaction, consequently enhancing the catalytic activity and long-term stability of gold-based catalysts.

In this study, single-crystal Pd nanocrystals with exposed (100) and (111) facets were prepared and their catalytic performance were compared in 2-ethylanthraquinone hydrogenation reaction through immobilization on γ-Al2O3 as catalyst. Our experimental results combined with density functional theory calculations showed that the Pd (100) facet was more active than Pd (111) in CO hydrogenation but less active in saturation of aromatic rings. Directed by this result, a high-performance Pd/γ-Al2O3 nanocatalyst was successfully prepared using a one-step synthesis method, which could not only control the exposure of the Pd (100) facet but also increase the stability of Pd components. This catalyst exhibited superior catalytic performance with a hydrogenation efficiency of up to 15.0 g L−1 and a selectivity of 99.1% under mild reaction conditions (0.2 MPa, 50 °C, 15 min), which was superior to that of the catalyst prepared by an impregnation method.

A chlorotriphenylphosphine gold (AuPPh3Cl) complex was successfully prepared using chloroauric acid and triphenylphosphine (TPP) and was used as a catalyst precursor in the preparation process of a Au-based catalyst. The AuPPh3Cl/AC catalyst was prepared by an incipient wetness impregnation method and its catalytic performance was evaluated in acetylene hydrochlorination reaction. Simultaneously, the AuPPh3Cl/AC catalyst was characterized by BET, TG, XRD, TEM, XPS, ICP, TPR and TPD techniques. The catalytic test result shows that the AuPPh3Cl/AC catalyst exhibits superior activity and stability with an acetylene conversion of 85% after 200 h of reaction under the conditions of 170 °C and an acetylene gas hourly space velocity of 360 h−1. The characterization results show that the presence of TPP can enhance the stability of Au+ and inhibit the reduction of Au3+ or Au+ species to Au0 species. In addition, the interaction between Au and TPP ligand can reduce the loss of Au species and inhibit the agglomeration of gold particles, thereby improving the catalytic activity and stability.

The catalytic mechanism of Ru-based catalysts in the acetylene hydrochlorination reaction has been investigated via the density functional theory (DFT) method. To study the effect of the chlorine coordination number on the catalytic mechanism, Ru3Cl9, Ru3Cl7, Ru5Cl7, Ru3Cl3 and Ru3 clusters were chosen as the catalytic models. Our results show that the energy barrier for acetylene hydrochlorination on Ru3Cl9 was as high as 1.51 eV at 458 K. When the chlorine coordination number decreased, the energy barriers on Ru3Cl7, Ru5Cl7, Ru3Cl3 and Ru3 were 1.29, 0.89, 1.01 and 1.42 eV, respectively. On Ru3Cl9, the H and Cl atoms of HCl were simultaneously added to C2H2 to form C2H3Cl, while the reaction was divided into two steps on Ru3Cl7, Ru3Cl3 and Ru3 clusters. The first step was the addition of H atom of HCl to C2H2 to form C2H3˙, and the second step was the addition of Cl atom to C2H3˙ to form C2H3Cl. The step involving the addition of Cl was the rate-controlling step during the whole reaction. On Ru5Cl7 cluster, there was an additional step before the steps involving the addition of H and Cl: the transfer of H atom from HCl to Ru atom. This step was the rate-controlling step during the reaction of acetylene hydrochlorination on Ru5Cl7 and its energy barrier was the lowest among all the above-mentioned catalytic models. Therefore, the Ru5Cl7 cluster played the most predominant role in acetylene hydrochlorination with the largest reaction rate constant kTST of 103.

First-principles density functional theory studies have been carried out to investigate the effects of perfect and defective anatase TiO2 supports on the structural stabilities and electronic properties of PdmAgn(m + n = 2–5) bimetallic clusters. Our results showed that the structures of supported Pd–Ag bimetallic clusters are distorted compared to their structures in the gas phase, which is caused by the balance of the cluster inner-interaction and the metal-support interfacial interaction. In particular, Pd1Ag3 and Pd1Ag4 clusters prefer to form three-dimensional structures on both perfect and defective anatase TiO2 support while their most stable structures in the gas phase are planar. In the most stable structures of supported PdmAgn bimetallic clusters, Pd atoms always occupy the most active sites of TiO2(101) surface, which induced Pd enriched at the interface of TiO2 support and Ag atoms exposed at the surface of the bimetallic cluster. As Ag% increases, the perfect TiO2 support gets more electrons from the Pd–Ag bimetallic cluster, which reduced the stability of the supported Pd–Ag cluster. The Mulliken population and electron density difference analysis demonstrated that the co-deposition of Ag induced the charge of adsorbed Pd on the perfect TiO2 support from positive to negative as a result of charge transfer from the half-filled s-orbital of Ag(5s1) to the d-orbit of Pd, and the negative charges of Pd on the defective TiO2 support were also increased by Pd–Ag charge polarization. Therefore, the selectivity of acetylene hydrogenation is enhanced by anatase-TiO2 supported Pd–Ag bimetallic catalyst as it serves as an electron donor.

A Ru-based catalyst (Ru/N-AC) was prepared using N-doped carbon as the support and the catalytic performance of the one-step synthesis reaction of vinyl chloride monomer (VCM) from acetylene and 1,2-dichloroethane (EDC) was assessed. It is indicated that 1% Ru/N-AC exhibited good catalytic activity with an initial acetylene conversion of 95.2% at 250 °C, an EDC total liquid hourly space velocity (LHSV) of 0.2 h−1 and a molar ratio n(EDC)/n(C2H2) of 1, much better than that of 1% Ru/AC or N-AC. Through BET, TG, XPS, ICP, TPR, TPD, TEM and XRD characterization, it is indicated that N-doped AC support can increase the amount of RuO2 and RuOx species in the catalyst and enhance its adsorption ability for both EDC and acetylene, suggesting that the N dopant and Ru species generated a synergistic effect in the one-step synthesis reaction of VCM.

Gold–cerium oxide catalysts were prepared to study the effects of cerium oxide additives on the catalytic performance of gold catalysts for acetylene hydrochlorination, using activated carbon as the support. The optimal catalytic performance is achieved over the 1Au–5CeO2/AC catalyst with an acetylene conversion of 98.4% and a selectivity to vinyl chloride monomer (VCM) of 99.9% after 20 h on stream under the conditions of 180 °C, C2H2 gas hourly space velocity (GHSV) of 852 h−1 and HCl/C2H2 feed volume ratio of 1.15. It is indicated that the addition of cerium oxide can make active Au species uniformly dispersed and improve the adsorption properties of reactants on the catalysts, but also suppress the reduction of active gold species and inhibit coke deposition on the catalyst surfaces during the reaction. Characterization was carried out using transmission electron microscopy, Raman spectroscopy, N2 adsorption/desorption analysis, thermogravimetric analysis, temperature-programmed reduction, temperature-programmed desorption, powder X-ray diffraction, atomic absorption spectroscopy and X-ray photoelectron spectroscopy.

Bimetallic gold–barium catalysts were prepared and assessed for acetylene hydrochlorination, and characterized using low-temperature N2 adsorption/desorption, thermogravimetric analysis, X-ray diffraction, temperature-programmed reduction/desorption, inductively coupled plasma-atomic emission spectroscopy, transmission electron microscopy, and X-ray photoelectron spectroscopy. The best catalytic performance is obtained over Au1Ba(II)1/AC catalysts with the acetylene conversion of 98.4% and the selectivity to VCM of 99.9%. It is indicated that the addition of Ba(II) can make Au species disperse well and inhibit carbon deposition on the catalyst surface; Ba(II) additives can enhance the adsorption of reactants on the catalysts but also inhibit the reduction of active gold species during the reaction, consequently augmenting the activity and long-term stability of gold catalysts.