Methanol synthesis in a three‐phase catalytic bed under nonwetted condition

To overcome the heat removal problem encountered in methanol synthesis at high syngas concentrations in the gas phase, a three‐phase nonwetted catalytic system was established by introducing an inert liquid medium into a fixed‐bed reactor. To form a repellent interface between the liquid and the catalyst, the catalyst was modified into hydrophobic, while the liquid medium was chosen as a room temperature ionic liquid with hydroxyl groups. The liquid‐solid contact angle was measured to be 115°, and only 20% of the catalyst external surface was wetted by the liquid. Under three‐phase condition, the reaction rate was measured to be 60%–70% of gas‐phase reaction, while it was merely 10%–20% for the fully wetted catalyst. From the resistance analysis on the mass transfer and reaction steps, the overall reaction rate is expected to increase further if the surface could be more wet proofed. © 2016 American Institute of Chemical Engineers AIChE J, 63: 226–237, 2017     

Effect of a novel amphipathic ionic liquid on lithium deposition in gel polymer electrolytes

A novel dimeric ionic liquid based on imidazolium cation and bis(trifluoromethanesulfonyl) imide (TFSI) anion has been synthesized through a metathesis reaction. Its chemical shift values and thermal properties are identified via ¹H nuclear magnetic resonance (NMR) imaging and differential scanning calorimetry (DSC). The effect of the synthesized dimeric ionic liquid on the interfacial resistance of gel polymer electrolytes is described. Differences in the SEM images of lithium electrodes after lithium deposition with and without the 1,1′-pentyl-bis(2,3-dimethylimidazolium) bis(trifluoromethane-sulfonyl)imide (PDMITFSI) ionic liquid in gel polymer electrolytes are clearly discernible. This occurs because the PDMITFSI ionic liquid with hydrophobic moieties and polar groups modulates lithium deposit pathways onto the lithium metal anode. Moreover, high anodic stability for a gel polymer electrolyte with the PDMITFSI ionic liquid was clearly observed.     

Molecular Dynamics Study of a Model SN1 Dissociation Reaction at Liquid/Liquid Interfaces: Effect of Liquid Polarity

The ionic dissociation step of the nucleophilic substitution reaction: t-BuCl → t-Bu⁺ + Cl⁻ is studied at the water/dichloroethane (DCE) interface using molecular dynamics computer simulations. The t-BuCl is modeled using an empirical valence bond method where two diabatic states, covalent and ionic, are coupled in the electronically adiabatic limit. Umbrella sampling is used to determine the potential of mean force (PMF) along the reaction coordinate R (defined as the t-Bu to Cl distance) in several interfacial regions of varying distances from the Gibbs dividing surface. The results at the water/DCE interface are compared to previous molecular dynamics calculations of t-BuCl at the water liquid/vapor and water/carbon tetrachloride interfaces. As in the other systems, the transition state shifts to larger R values, and the activation barrier and ΔG_rxn increase with decreasing solvent polarity. In contrast with the water/carbon tetrachloride interface, a well-defined transition state exists at the water/DCE interface and persists even as the solute is moved 3 to 6 Å into the DCE phase. Dynamical flux correlation calculations reveal larger deviation of the rate from TST than in bulk water due to slower vibrational relaxation of the product ions. However, the increased density at the water/DCE interface increases the rate of dissociation relative to the water liquid/vapor interface. The transmission coefficient at the water/DCE interface was found to be 25% of the TST rate prediction, or about twice the rate at the water liquid/vapor interface.     

Thermodynamic Modeling of the HfO2–La2O3–Al2O3 System

Based on phase equilibria, thermodynamic, and crystal structure data, the thermodynamic modeling of HfO₂–La₂O₃–Al₂O₃ system is presented. Liquid phase is described by the modified quasichemical model considering the short‐range ordering in liquid solution. Solid solutions are described by the ionic sublattice model considering respective crystal structure. The model (La³⁺, Hf⁴⁺)₂(Hf⁴⁺, La³⁺)₂(O^2?, Va)₆(O^2?)₁(Va, O^2?)₁ successfully describes the structure defect, homogeneity range, and thermodynamic property of pyrochlore solid solution. A set of optimized model parameters is obtained which reproduces most experimental data well. Isothermal sections, liquidus and solidus projections, and Scheil reaction scheme are constructed.     

Stabilizing the Meniscus for Operando Characterization of Platinum During the Electrolyte-Consuming Alkaline Oxygen Evolution Reaction

Achieving a molecular-level understanding of interfacial (photo)electrochemical processes is essential in order to tailor novel and highly-performing catalytic systems. The corresponding recent development of in situ and operando tools has posed new challenges on experimental architectures. In this study, we use ambient pressure X-ray photoelectron spectroscopy (AP-XPS) to probe the solid/liquid electrified interface of a polycrystalline Pt sample in contact with an alkaline electrolyte during hydrogen and oxygen evolution reactions. Using the “dip-and-pull” technique to probe the interface through a thin liquid layer generated on the sample surface, we observe that the electrolyte meniscus becomes unstable under sustained driving of an electrolyte-consuming reaction (such as water oxidation). The addition of an electrochemically inert supporting electrolyte mitigates this issue, maintaining a stable meniscus layer for prolonged reaction times. In contrast, for processes in which the electrolyte is replenished in the reaction pathway (i.e. water reduction in alkaline conditions), we find that the solid/liquid interface remains stable without addition of a secondary supporting electrolyte. The approach described in this work allows the extension of operando AP-XPS capabilities using the “dip-and-pull” method to a broader class of reactions consuming ionic species during complex interfacial faradaic processes.     

Gas‐Liquid Mass Transfer in a Bench‐Scale Trickle Bed Reactor used for Benzene Hydrogenation

The gas‐liquid mass transfer coefficients (MTCs) of a trickle bed reactor used for the study of benzene hydrogenation were investigated. The Ni/Al₂O₃ catalyst bed was diluted with a coarse‐grained inert carborundum (SiC) particle catalyst. Gas‐liquid mass transfer coefficients were estimated by using a heterogeneous model for reactor simulation, incorporating reaction kinetics, vapor‐liquid equilibrium, and catalyst particle internal mass transfer apart from gas‐liquid interface mass transfer. The effects of liquid axial dispersion and the catalyst wetting efficiency are shown to be negligible. Partial external mass transfer coefficients are correlated with gas superficial velocity, and comparison between them and those obtained from experiments conducted on a bed diluted with fine particles is also presented. On both sides of the gas‐liquid interface the hydrogen mass transfer coefficient is higher than the corresponding benzene one and both increase significantly with gas velocity. The gas‐side mass transfer limitations appear to be higher in the case of dilution with fine particles. On the liquid side, the mass transfer resistances are higher in the case of dilution with coarse inerts for gas velocities up to 3 · 10^–2 cm/sec, while for higher gas velocities this was inversed and higher mass transfer limitations were obtained for the beds diluted with fine inerts.     

Physico-chemical limitations during the electrokinetic treatment of a polluted soil

The influence of the ion-exchange solid/liquid reaction on electrokinetic transport phenomena was studied and modelled for a non-permeable porous medium composed of kaolin. Kaolin was selected to model a low-permeable medium, even though it is usually considered to have low ion-exchange capacity and weak selectivity. The influence of this reaction on the characteristic time of the process was demonstrated by studying the lithium (Li⁺) electrokinetic transport on a sodium (Na⁺) pre-saturated kaolin. Experimental results were obtained using apparatus developed specifically for the study of the electrokinetic transport and which has been well characterized in previous works. The tests were performed by introducing a solution containing Li⁺ at the anode, and measuring the Na⁺ and Li⁺ concentrations at the cathode outlet. Under operating conditions, local equilibrium is assumed in the medium. The equilibrium isotherm of Li⁺/Na⁺ exchange was determined by independent experiments on a laboratory column. Ion-exchange equilibrium can be satisfactorily described by a linear isotherm. A theoretical model based on the tanks-in-series model was used for modeling the experimental results of the Li⁺ electrokinetic transport. This model considers electro-migration and electro-osmosis as the only transport mechanisms, and takes into account the solid/liquid reaction by a retardation factor, as is usually the case for linear equilibrium models. The comparison between experimental and theoretical results shows that the chemical solid/liquid reaction at least doubles the characteristic time of the transport.     

沉积型和热液型重晶石的煅烧和浸取

论述了沉积型和热液型重晶石基本性质的不同和所应选择的煅烧和浸取方式。并就煅烧和浸取的工艺设备提出了新的观点。对提高重晶石的利用率、优化工艺设备,降低生产成本、保护环境是非常必要的。     

Doped polyaniline in Brønsted acid ionic liquid 1‐butyl‐3‐methylimidazolium bis[trifluoromethyl(sulfonyl)]imide/bis[trifluoromethyl(sulfonyl)]imide

We report the preparation and characterization of doped polyaniline (PANI) in an ionic liquid 1‐butyl‐3‐methylimidazolium bis[trifluoromethyl(sulfonyl)]imide (BMImTFSI) medium. Aniline monomer was chemically polymerized via oxidation with KMnO₄ in an ionic liquid BMImTFSI solution containing a monoprotic Brønsted acid bis[trifluoromethyl(sulfonyl)]imide (HTFSI). HTFSI is the source of proton that doped PANI. The identity of PANI as the reaction product was confirmed with both ultraviolet–visible and Fourier transform infrared spectra. Unlike syntheses in aqueous media, the doped PANI did not readily precipitate from the ionic liquid; a transparent and stable green solution‐like liquid dispersion was obtained (dispersion is used to refer the product hereafter). PANI precipitated when dedoped with organic bases such as triethylamine. The PANI precipitate can be redoped by HCl and the so‐doped PANI has conductivity of about 2.0 × 10^?2 S/cm. The liquid dispersion of doped PANI in the ionic liquid can be diluted by many organic solvents or other ionic liquids to diluted “solutions.” © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

A generalized CFD model for evaluating catalytic separation process in structured porous materials

A hybrid multiphase model is developed to simulate the simultaneous momentum, heat and mass transfer and heterogeneous catalyzed reaction in structured catalytic porous materials. The approach relies on the combination of the volume of fluid (VOF) and Eulerian–Eulerian models, and several plug-in field functions. The VOF method is used to capture the gas–liquid interface motion, and the Eulerian–Eulerian framework solves the temperature and chemical species concentration equations for each phase. The self-defined field functions utilize a single-domain approach to overcome convergence difficulty when applying the hybrid multiphase for a multi-domain problem. The method is then applied to investigate selective removal of specific species in multicomponent reactive evaporation process. The results show that the coupling of catalytic reaction and interface species mass transfer at the phase interface is conditional, and the coupling of catalytic reaction and momentum transfer across fluid–porous interface significantly affects the conversion rate of reactants. Based on the numerical results, a strategy is proposed for matching solid catalyst with operating condition in catalytic distillation application.     

Predispersed solvent extraction of negatively complexed copper from water using colloidal liquid aphron containing a quaternary ammonium salt

Negatively complexed copper ion by complexing agent like EDTA (Ethylenediaminetetraacteic acid) was removed by predispered solvent extraction (PDSE) using colloidal liquid aphrons (CLAs) made out of Trioctylmetylammonium chloride (Aliquat 336) diluted with nonpolar kerosene. PDSE was found to have higher mass transfer rate than conventional solvent extraction under experimental conditions without mechanical mixing. The effect of type of water-soluble surfactants, phase volume ratio (PVR), concentration of anionic Sodium Dodecyl Benzene Sulfonate (SDBS) on PDSE was investigated. In addition, the effect of anionic SDBS on back extraction in PDSE was also studied. Under experimental conditions with enough mechanical mixing, the amount of copper transferred to Aliquat 336 core from the pregnant phase was compared in both PDSE by using anionic SDBS and conventional solvent extraction. It is concluded that PDSE using Aliquat 336 CLA can be used for treatment of negatively complexed copper without the influence of surfactant. To optimize CLAs-based process, stability of CLAs containing a quaternary ammonium salt Aliquat 336 diluted with kerosene in the continuous phase was investigated by measuring the volume released to surface. To destabilize CLAs, H⁺, OIL were added. Stability of CLAs was estimated by comparing the half-life obtained. Break-up of destabilization follows pseudo-first-order reaction kinetics at low ionic strength. But, pseudo-first-order model cannot be applied to a region of high ionic strength.     

Chemical compatibility of rare earth apatite with yttria-stabilized zirconia

The chemical compatibility of a series of rare earth apatite (RE-apatite), with Y₂O₃-stabilized ZrO₂ (YSZ) has been investigated. Three types of RE-apatite powders with different ionic radius (RE = Gd, Nd and La) were prepared, and bulks prepared from the powder mixtures of RE-apatite and YSZ were heat-treated at 1300 °C up to 100 h in this study. It was found that Gd-apatite reacted with YSZ and formed a reaction layer (Gd₂Si₂O₇) at the Gd-apatite/YSZ interface. Meanwhile, the intense Gd³⁺ diffusion resulted in the formation of Gd solid solutions in YSZ and much YSZ phase transformation. In contrary, as for Nd- or La-apatite/YSZ composite, which has larger ionic radius, no reaction product was observed at interface and there was less RE diffusion into YSZ as well as YSZ transformation. These results clearly indicated that large ionic radius of RE³⁺ could enhance the chemical compatibility of RE-apatite with YSZ.     

ATR-FTIR Study of the Decomposition of Acetic Anhydride on Fosfotungstic Wells–Dawson Heteropoly Acid Using Concentration-Modulation Excitation Spectroscopy

The decomposition of acetic anhydride in liquid phase on a fosfotungstic Wells–Dawson heteropoly acid (HPA) was investigated by in situ ATR-FTIR spectroscopy. Transient and concentration-modulation excitation spectroscopy (MES) experiments in combination with phase-sensitive detection (PSD) were used to monitor the solid–liquid interface. The MES method is based on the periodic variation of a parameter of the reaction media such as, the reactant concentration. That periodic alteration causes varying infrared signals of the surface adsorbed species that are subsequently demodulated with the PSD methodology. Thus, the separation of the static signals from the changing ones is achieved, and species with different response can be observed in the spectra. Using MES-PSD coupled with ATR-FTIR, acetic anhydride was observed to decompose to acetic acid, acetate and acyl [CH₃C(O)⁺] species, involving Brønsted acid sites of the HPA catalyst. The CH₃C(O)⁺ is a very unstable intermediate species and it is the key intermediate in the Friedel–Crafts acylation reactions. Moreover, the acetate groups are spectator species since remain strongly adsorbed on the catalyst surface and do not further react.     

环己酮肟Beckmann重排制己内酰胺的研究进展

环己酮肟Beckmann重排制己内酰胺是重要的工业过程。本文较详细地介绍了不使用浓硫酸催化的反应，主要有气固相反应、固液相反应、离子液体系及超临界水条件下的反应。研究表明：气固相反应中，副产物较多，催化剂易失活，使用寿命短；固液相反应条件温和，且副产物少；离子液体系和超临界水条件下的Beckmann反应中，可避免使用有机溶剂，且反应副产物少。     

Energetic use of the tomato plant waste

A study of the conventional pyrolysis of the tomato plant waste has been carried out. The objective of this work was to characterize the solid, liquid and gaseous phases obtained in the process for their possible utilization in energy generation. Also, a study of the influence of operation variables has been performed, determining the optimal conditions in which the process can be accomplished. The operation variables studied were temperature (400–800 °C), the initial sample mass (2.5–10 g of tomato plant waste) and the particle size (0.63–2.00 mm). Under the conditions studied here, an increase in reaction temperature leads to a decrease in solid and liquid yields and to an increase in gas phase yield. However the variation in the initial sample mass and the particle size does not seem to exert a defined influence in the yield of the different phases. The higher heating value (HHV) of solids and liquids was determined; also the immediate analysis of the solid phase was carried out. The gas phase, mainly composed of H₂, CO, CH₄, CO₂ and traces of ethane and ethylene, was analyzed chromatographically. The solid phase is constituted for a charcoal with an average higher heating value of 26 MJ kg^− 1, the liquid phase presents a HHV of 7.8 MJ kg^− 1 at 400 °C, this value diminishes when the temperature is increased, and the gas phase has an HHV between 0.5 and 8.0 MJ (kg of raw material)^− 1. According to their characteristics and energy contents, the solid phase can be used as fuel or precursor for the manufacture of activated carbons. The liquid phase could be used as liquid fuel or as organic-compounds source. The gas phase could be used to heat the pyrolysis reactor or to generate heat and electricity in a gas-turbine/vapour-turbine combined cycle. Finally, as previous step to the design of the industrials equipments, a kinetic study of the process, based in the generation of the principal gases, has been carried out. For this study it has been considered that the gases are formed through parallel independent first-order reactions, with different activation energy. From this model, rate constants for the formation of each gas component and their corresponding activation energies were determined.     

Simulating simultaneous fines deposition under catalytic hydrodesulfurization in hydrotreating trickle beds—does bed plugging affect HDS performance?

The deposition of fine particles under chemical reaction conditions in a high pressure/temperature trickle bed reactor was analyzed theoretically using a dynamic multiphase flow deep-bed filtration model coupled with heat and species balance equations in the liquid, gas and solid (catalyst+deposit) phases. The hydrodesulfurization process in the presence of sulfided Co-Mo/γ-Al₂O₃ catalyst was considered as a case study. The deep-bed filtration model incorporates the physical effects of porosity and effective specific surface area changes due to fines deposition/detachment, gas and suspension inertial effects, and coupling effects between the filtration parameters and the interfacial momentum exchange force terms. The detachment of the fine particles from the collector surface was assumed to be induced by the colloidal forces in the case of Brownian particles or by the hydrodynamic forces in the case of non-Brownian particles. The three-phase heterogeneous model developed to simulate the trickle bed performance incorporates the concentration gradients inside the catalyst particle and solid deposit. An important finding of the work is that fine particles deposition does not influence appreciably trickle bed reactor performance. Thus, the only undesirable effect of the fine particles deposition process is the bed plugging and the increase of the resistance to two-phase flow.     

Solvent-assisted ball milling for synthesizing solid electrolyte Li7P3S11

Solvent-assisted ball milling is used to prepare the sulfide solid electrolyte Li₇P₃S₁₁. Comparing with dry ball milling and simple liquid phase synthesis, solvent-assisted ball milling can significantly promote the reaction of the starting materials from tens of hours to only several hours. When using dimethoxyethane as the assistant solvent, relatively pure Li₇P₃S₁₁ with ionic conductivity of 1.0 × 10⁻⁴ S/cm can be synthesized after 8-hour ball milling with following 2-hour 180°C vacuum drying and 4-hour 230°C heat treatment. It is revealed that the transition from the precursor to Li₇P₃S₁₁ is a two-step process, with an intermediate composed of a thio-LISICON III analogous phase and an amorphous phase. This work not only provides a synthesis route of Li₇P₃S₁₁ which reduces synthesis duration, but also offers an instructive insight into the phase evolution in solvent-based synthesis process of sulfide solid electrolytes.     

Lipase immobilization on ionic liquid‐modified magnetic nanoparticles: Ionic liquids controlled esters hydrolysis at oil–water interface

Ester hydrolysis at oil–water interface by lipase covalently immobilized on ionic liquid‐modified magnetic nanoparticles was investigated. Magnetic supports with a diameter of 10–15 nm were synthesized by covalent binding of ionic liquids (chain length C₄ and C₈ and anions Cl^?, BF₄^?, and PF₆^?) on the surface of Fe₃O₄ nanoparticles. Lipase was covalently immobilized on Fe₃O₄ nanoparticles using ionic liquids as the coupling reagent. Ionic liquid‐modified magnetic nanoparticle‐grafted lipase preferentially located at the oil–water interface. It has higher catalytic activity than its native counterpart. A modified Michaelis–Menten model was used to elucidate the effect of stirring rate, aqueous–organic phase ratio, total amount of enzyme, and ester chain length. The influences of these conditions on esters hydrolysis at oil–water interface were consistent with the introduction of the ionic liquids interlayer. Ionic liquids could be used to control the oil–water interfacial characteristics during lipase catalyzed hydrolysis, and thus control the behavior of immobilized lipase. © 2011 American Institute of Chemical Engineers AIChE J, 2012     

Cation transfer across a hydrogel/organic phase: Effect of cation size, hydrophobicity and acid-base properties

The transfers of tetraethylammonium (TEA⁺) and protonated triflupromazine (HTFP⁺) through a hydrogel/liquid interface (g/o) and a liquid/liquid interface (w/o) were compared using cyclic voltammetry. After the two phases were put in contact, the behavior of each molecule was analyzed at different pH values and at different time points. The gel induces hydrophobic and electrostatic interactions with TEA⁺ and HTFP⁺, shifting the peak potentials to more positive values. The diffusion coefficients, D, in both phases (g and w) at different pH values were calculated. In the case of TEA⁺, the D value remains constant in both systems. However, the D value of HTFP⁺ is lower in the gel phase than in the liquid phase.HTFP⁺ is transferred from the aqueous phase to the organic phase via a direct mechanism that involves coupled acid-base and partition processes. At the g/o interface, the coupled chemical reactions of HTFP⁺ were inhibited by the drug/gel interaction. The results demonstrate that the g/o system could be used as a model to study the controlled release of charged drugs.     

Extractive distillation with the mixture of ionic liquid and solid inorganic salt as entrainers

The use of the mixture of ionic liquid (IL) and solid inorganic salt in place of the single IL as entrainers for extractive distillation, which integrates the advantages of a liquid solvent, that is, IL (easy operation and nonvolatility) and a solid salt (high separation ability) has been proposed in this work. The vapor–liquid equilibrium experiments indicated that the combination of [EMIM]⁺[Ac]^? and KAc is the most promising for the separation of ethanol and water among all of the entrainers investigated. Based on the thermodynamic study, the conceptual process design was developed to evaluate the competitiveness of the suggested entrainers for the separation of ethanol and water. It was determined that the overall heat duty on reboilers in the extractive distillation process using the new mixed entrainers decreases 19.04% compared with the benchmark entrainer [EMIM]⁺[Ac]^?. Moreover, the density functional theory and COSMO‐RS model were used to achieve theoretical insights at the molecular level. © 2014 American Institute of Chemical Engineers AIChE J, 60: 2994–3004, 2014