Preparation and coordination with Hg(II) of sulfur‐ and 2‐amino‐pyridine‐containing chelating resin

A novel chelating resin anchoring 2‐amino‐pyridine on macroporous crosslinked polystyrene beads via a sulfur‐containing spacer (PVBS‐AP) has been synthesized and its structures were characterized by FTIR, scanning electron microscopy, porous structure analysis, and elementary analysis. The results of scanning electron microscopy and pores analysis demonstrated that PVBS‐AP resin had meso‐macro porous structure. Its adsorption properties for Hg(II), Pd(II), Ni(II), Cu(II), Zn(II), Pb(II), and Cd(II) were investigated. Some factors affecting the adsorption of PVBS‐AP resin for Hg(II), such as temperature, contact time, ion concentration, and pH were also studied. The results showed that the increasing of temperature was beneficial to adsorption and Langmuir model was much better than Freundlich model to describe the isothermal process. PVBS‐AP resin had good adsorption selectivity for Hg(II). It could selective adsorb Hg(II) from such binary ions system as Hg(II)‐Ni(II), Hg(II)‐Zn(II), and Hg(II)‐Pb(II), their selective coefficients are α_Hg/Ni = ∞, α_Hg/Zn = 28.1, α_Hg/Pb = ∞, respectively. Five adsorption–desorption cycles demonstrate that this resin were suitable for reuse without considerable change in adsorption capacity. POLYM. ENG. SCI., 47:721–727, 2007. © 2007 Society of Plastics Engineers.     

High‐Temperature Aging of Plasma Sprayed Quasi‐Eutectoid LaYbZr2O7‐Part I: Phase Evolution

Phase and microstructure stability is an important issue for the durability and performance of thermal barrier coating (TBC) materials which have to work at high temperature for long time. In this work, we present a meta‐stable structure LaYbZr₂O₇ by air plasma spraying process, which can convert into thermodynamically stable fine‐grained quasi‐eutectoid structure with enhanced thermal insulation properties even under high‐temperature annealing. In this part, we first report on the phase composition and relationship in the LaYbZr₂O₇ coatings. The as‐sprayed LaYbZr₂O₇ coatings initially exhibited a mixture of amorphous phase and a nonequilibrium fluorite phase. Then it underwent a fast crystallization and a quasi‐eutectoid transformation during the first few hours of annealing at 1300°C. The phase constitution quickly reached an equilibrium state consisting of La‐rich pyrochlore phase and Yb₂Zr₂O₇ fluorite phase after 6 h annealing and kept stable ever since. Coherent phase boundaries were observed between the La‐rich pyrochlore and Yb₂Zr₂O₇ fluorite phase, indicating a lower interface energy, a lower ionic diffusion rate, a higher strength and creeping resistance of this material at high temperature, all of which could be particularly advantageous to a TBC material for high‐temperature gas turbine applications.     

Modeling of CO2‐Hydrate Formation at the Gas‐Water Interface in Sand Sediment

Sub‐seabed geological storage of CO₂ in the form of gas hydrate is attractive because clathrate hydrate stably exists at low temperature and high pressure, even if a fault occurs by diastrophism like a big earthquake. For the effective design of the storage system it is necessary to model the formation of CO₂‐hydrate. Here, it is assumed that the formation of gas hydrate on the interface between gas and water consists of two stages: gas diffusion through the CO₂‐hydrate film and consequent CO₂‐hydrate formation on the interface, between film and water. Also proposed is the presence of a fresh reaction interface, which is part of the interface between the gas and aqueous phases and not covered with CO₂‐hydrate. Parameters necessary to model the hydrate formation in sand sediment are derived by comparing the results of the present numerical simulations and the measurements in the literature.     

Theoretical and Experimental Studies on Acetylene Absorption in a Polytetrafluoroethylene Hollow‐Fiber Membrane Contactor

The separation of acetylene from a gas mixture was investigated using a polytetrafluoroethylene hollow‐fiber membrane contactor and 1‐methyl‐2‐pyrrolidinone as absorbent. The effects of the gas velocity, the liquid velocity, the feed gas concentration, and the module length on the acetylene mass transfer were investigated. The results showed that the acetylene mass transfer flux increased with increasing liquid velocity, gas velocity, and feed gas concentration, but decreased with increasing membrane module length. A mathematical model was used to predict the wetting extent of the membrane and the mass transfer resistance in the acetylene mass transfer process. The wetting extent of the membrane was found to increase with increasing liquid velocity and to be effectively restrained with increasing gas velocity. The liquid phase resistance and the wetted‐membrane phase resistance controlled the acetylene mass transfer in the acetylene absorption process. The acetylene absorption efficiency was maintained at 90 % for 114 h of the C₂H₂ membrane absorption–thermal desorption cycle process.     

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.     

Kinetics of hydrogenation of 4‐chloro‐2‐nitrophenol catalyzed by Pt/carbon catalyst

Hydrogenation of 4‐chloro‐2‐nitrophenol (CNP) was carried out at moderate hydrogen pressures, 7–28 atm, and temperatures in the range 298–313 K using Pt/carbon and Pd/γ‐Al₂O₃ as catalysts in a stirred pressure reactor. Hydrogenation of CNP under the above conditions gave 4‐chloro‐2‐aminophenol (CAP). Dechlorination to form 2‐aminophenol and 2‐nitrophenol is observed when hydrogenation of CNP is carried out above 338 K, particularly with Pd/γ‐Al₂O₃ catalyst. Among the catalysts tested, 1%Pt/C was found to be an effective catalyst for the hydrogenation of CNP to form CAP, exclusively. To confirm the absence of gas–liquid mass transfer effects on the reaction, the effect of stirring speed (200–1000 rpm) and catalyst loading (0.02–0.16 g) on the initial reaction rate at maximum temperature 310 K and substrate concentration (0.25 mole) were thoroughly studied. The kinetics of hydrogenation of CNP carried out using 1%Pt/C indicated that the initial rates of hydrogenation had first order dependence with respect to substrate, catalyst and hydrogen pressure in the range of concentrations varied. From the Arrhenius plot of ln rate vs 1000/T, an apparent activation energy of 22 kJ mol^?1 was estimated. © 2001 Society of Chemical Industry     

Continuous Gas‐Phase Hydroformylation of 1‐Butene using Supported Ionic Liquid Phase (SILP) Catalysts

The concept of supported ionic liquid phase (SILP) catalysis has been extended to 1‐butene hydroformylation. A rhodium‐sulfoxantphos complex was dissolved in [BMIM][n‐C₈H₁₇OSO₃] and this solution was highly dispersed on silica. Continuous gas‐phase experiments in a fixed‐bed reactor revealed these SILP catalysts to be highly active, selective and long‐term stable. Kinetic data have been acquired by variation of temperature, pressure, syngas composition, substrate and catalyst concentration. A linear dependency in rhodium concentration could be established over a large concentration range giving another excellent hint for truly homogeneous catalysis in the SILP system. Compared to former studies using propene, the SILP system showed significantly higher activity and selectivity with 1‐butene as feedstock. These findings could be elucidated by solubility measurements using a magnetic microbalance.     

Determination of kinetics of CO2 absorption in solutions of 2‐amino‐2‐methyl‐1‐propanol using a microfluidic technique

The kinetics for the reactions of carbon dioxide with 2‐amine‐2‐methyl‐1‐propanol (AMP) and carbon dioxide (CO₂) in both aqueous and nonaqueous solutions were measured using a microfluidic method at a temperature range of 298–318 K. The mixtures of AMP‐water and AMP‐ethylene glycol were applied for the working systems. Gas‐liquid bubbly microflows were formed through a microsieve device and used to determine the reaction characteristics by online observation of the volume change of microbubbles at the initial flow stage. In this condition, a mathematical model according to zwitterion mechanism has been developed to predict the reaction kinetics. The predicted kinetics of CO₂ absorption in the AMP aqueous solution verified the reliability of the method by comparing with literatures’ results. Furthermore, the reaction rate parameters for the reaction of CO₂ with AMP in both solutions were determined. © 2015 American Institute of Chemical Engineers AIChE J, 61: 4358–4366, 2015     

Gas‐liquid mass transfer in low‐ and medium‐consistency pulp suspensions

The volumetric gas—liquid mass transfer coefficient (k_La) was measured for low‐ and medium‐consistency pulp suspensions using the cobalt‐catalyzed sulfite oxidation technique. Mass transfer rates were measured in a high‐shear mixer for a range of operating parameters, including the rotor speed (N = 10 to 50 rev/s), gas void fraction (X_g = 0.10 to 0.40) and fibre mass concentration (C_m = 0.0 to 0.10). k_La measurements were compared with the macroscale flow regime in the vessel (characterized using photographic techniques) and correlated with energy dissipation, gas void fraction and suspension mass concentration in the mixer. We found that gas‐liquid mass transfer was significantly reduced in pulp suspensions, even for low suspension concentrations. Part of this reduction was associated with dissolved components leached from the fibres into the liquid phase. This could account for reductions in k_La of up to 30% when compared with distilled water. The fibres further reduced k_La, with the magnitude of the decrease depending on the fibre mass concentration. Correlations were developed for k_La and compared with results available in the literature.     

Synthesis and Surface Properties of a Novel Sodium 3‐(3‐Alkyloxy‐3‐oxopropoxy)‐3‐oxopropane‐1‐sulfonate at the Air–Water Interface

The present paper describes the synthesis and evaluation of surface properties of a novel series of anionic surfactant, namely sodium 3‐(3‐alkyloxy‐3‐oxopropoxy)‐3‐oxopropane‐1‐sulfonate with varying alkyl chain length (C8–C16). Synthesis involves initial formation of the 3‐alkyloxy‐3‐oxopropyl acrylate along with fatty acrylate during the direct esterification of fatty alcohol with acrylic acid in the presence of 0.5 % NaHSO₄ at 110 °C followed by sulfonation of the terminal double bond of the 3‐alkyloxy‐3‐oxopropyl acrylate. Synthesized compounds were evaluated for surface and thermodynamic properties such as critical micelle concentration (CMC), surface tension at CMC (γ_cmc), efficiency of surface adsorption (pC₂₀), surface excess (Γ_max), minimum area per molecule at the air–water interface (A_min), free energy of adsorption (?G°_ads), free energy of micellization (?G°_mic), wetting time, emulsifying properties, foaming power and calcium tolerance. Effect of chain length on CMC follows the classic trend, i.e. decrease in CMC with the increase in alkyl chain length. High pC₂₀ (>3) value indicates higher hydrophobic character of the surfactant. These surfactants showed very poor wetting time and calcium tolerance, but exhibited good emulsion stability and excellent foamability. Foaming power and foam stability of C14‐sulfonate were found to be the best among the studied compounds. Foam stability of C14‐sulfonate was also studied at different concentrations over time and excellent foam stability was obtained at a concentration of 0.075 %. Thus this novel class of surfactant may find applications as foam boosters in combination with other suitable surfactants.     

High‐Temperature Aging of Plasma Sprayed Quasi‐Eutectoid LaYbZr2O7–Part II: Microstructure & Thermal Conductivity

LaYbZr₂O₇ ceramic thermal barrier coatings (TBC) of meta‐stable structure were prepared by an air plasma spraying process. Their microstructure and associated thermal transport properties evolution during high‐temperature annealing at 1300°C were characterized. The as‐sprayed LaYbZr₂O₇ TBCs underwent a fast crystallization and a quasi‐eutectoid transformation during annealing, resulting in a biphase composite consisting of La‐rich pyrochlore phase and Yb₂Zr₂O₇ fluorite phase with coherent phase boundaries. Due to the diffusion barriers between the two phases as well as the low interface energy of the coherent boundaries, sintering and grain growth of materials was significantly refrained. Therefore, a final thermal dynamically stable microstructure with a grain size of ~300 nm and a total porosity about 5% could be maintained even after long‐term aging at a high temperature of 1300°C. Resulting from this stable microstructure, an ultralow thermal conductivity of 1.3 W·(m·K)^?1 could be obtained even after 216 h high‐temperature aging, which is much lower than that of the state‐of‐art 7 wt% yttria‐stabilized zirconia TBCs. Both the high phase and microstructure stability and the extremely low thermal conductivities could be particularly beneficial for TBC material in gas turbine applications.     

CO2 Capture Using Monoethanolamine in a Bubble‐Column Scrubber

A continuous bubble‐column scrubber, capturing CO₂ gas by monoethanolamine (MEA) solution in a pH‐stat operation, is used to search for optimum process parameters by means of the Taguchi method. The process variables are the pH of the solution, gas flow rate, concentration of CO₂ gas, and temperature. From the measured outlet CO₂ gas concentrations, the absorption rate and overall mass transfer coefficient can be determined with the support of a steady‐state material balance equation as well as a two‐film model. According to the signal‐to‐noise ratio, the significance sequence influencing the parameters and optimum conditions can be determined. CO₂ concentration and pH value proved to be decisive parameters, while temperature and gas flow rate were minor. Five sets of optimum conditions were obtained and could be further verified by empirical equations.     

Kinetics of homogeneous 5‐hydroxymethylfurfural oxidation to 2,5‐furandicarboxylic acid with Co/Mn/Br catalyst

2,5‐furandicarboxylic acid (FDCA) is a potential non‐phthalate based bio‐renewable substitute for terephthalic acid‐based plastics. Herein, we present an investigation of the oxidation rate of 5‐hydroxymethylfurfural (HMF) to FDCA in acetic acid medium using Co/Mn/Br catalyst. Transient concentration profiles of the reactant (HMF), intermediates [2,5‐diformylfuran (DFF), 5‐formyl‐2‐furancarboxylic acid (FFCA)], and the desired product (FDCA) were obtained for this relatively fast reaction in a stirred semi‐batch reactor using rapid in‐line sampling. Comparison of the effective rate constants for the series oxidation steps with predicted gas–liquid mass transfer coefficients reveals that except for the FFCA → FDCA step, the first two oxidation steps are subject to gas–liquid mass transfer limitations even at high stirrer speeds. Novel reactor configurations, such as a reactor in which the reaction mixture is dispersed as fine droplets into a gas phase containing oxygen, are required to overcome oxygen starvation in the liquid phase and further intensify FDCA production. © 2016 American Institute of Chemical Engineers AIChE J, 63: 162–171, 2017     

Fabrication of BaZr0.1Ce0.7Y0.2O3 – δ ‐Based Proton‐Conducting Solid Oxide Fuel Cells Co‐Fired at 1,150 °C

Dense proton‐conducting BaZr_0.1Ce_0.7Y_0.2O_{3 – δ} (BZCY) electrolyte membranes were successfully fabricated on NiO–BZCY anode substrates at a low temperature of 1,150 °C via a combined co‐press and co‐firing process. To fabricate full cells, the LaSr₃Co_1.5Fe_1.5O_{10 – δ}–BZCY composite cathode layer was fixed to the electrolyte membrane by two means of one‐step co‐firing and two‐step co‐firing, respectively. The SEM results revealed that the cathode layer bonded more closely to the electrolyte membrane via the one‐step co‐firing process. Correspondingly, determined from the electrochemical impedance spectroscopy measured under open current conditions, the electrode polarisation and Ohmic resistances of the one‐step co‐fired cell were dramatically lower than the other one for its excellent interface adhesion. With humidified hydrogen (2% H₂O) as the fuel and static air as the oxidant, the maximum power density of the one‐step co‐fired single cell achieved 328 mW cm^–2 at 700 °C, showing a much better performance than that of the two‐step co‐fired single cell, which was 264 mW cm^–2 at 700 °C.     

Optimization of a Pilot‐Scale Amine Scrubber to Remove SO2: Higher Selectivity and Lower Solvent Consumption

A pilot‐scale study of flue gas desulfurization based on an amine‐based solvent using applicable industrial values was carried out for sulfur dioxide (SO₂) removal. The plant consisting of absorption and desorption columns was operated with different working parameters such as solvent flow rate, inlet concentration of SO₂, temperature of desorption column, and pH of absorption agent. The Taguchi method was utilized to obtain the best combination of working parameters for the most efficient reduction of SO₂ outlet concentration. The industrial gas‐to‐liquid ratio could be optimized by applying a defined SO₂ concentration, stripper temperature, and solvent pH value. The achieved efficiency is much better compared to our previous study while the gas‐to‐liquid ratio is higher in this work.     

Promoted Fe2O3‐Al2O3‐CuO Chromium‐Free Catalysts for High‐Temperature Water‐Gas Shift Reaction

Promoted Fe₂O₃‐Al₂O₃‐CuO (FAC) chromium‐free catalysts were prepared for high‐temperature water‐gas shift reactions and characterized by X‐ray diffraction (XRD), Brunauer‐Emmett‐Teller method (BET), temperature‐programmed reduction (TPR), and transmission electron microscopy (TEM) techniques. The catalytic results revealed that among the investigated promoted catalysts with Ce, La, Zn, Y, and Mn as promoters, the Mn‐promoted sample showed higher activity compared to the other promoted catalysts. Increasing the Mn content improved the surface area and catalytic activity. The FAC catalyst promoted with a high Mn content exhibited maximum activity and relatively high stability in high‐temperature water‐gas shift reaction.     

Simulation and Experimental Validation of Two‐Phase Flow in an Aerosol Counter‐Flow Reactor using Computational Fluid Dynamics

A simulation of the hydrodynamic behavior of an aerosol‐counter flow reactor was conducted using an Euler‐Lagrange method. The simulation results were then verified with experiments. The process simulated was a separation process required during the production of biodiesel (fatty acid methyl ester). In this process, the liquid ester/glycerol phases are continuously injected through a hollow cone nozzle with an overpressure of 10⁶ Pa into the reactor, operated at 15000 Pa. The liquid is atomized because of the pressure drop and a liquid particle spray is generated with an inlet velocity of 44.72 m/s. Water vapor of temperature 333 K is injected tangentially through two side, gas inlets with an inlet velocity of 1.2 m/s. Excess methanol is subjected to a mass transfer from the liquid phase into the gas phase, which is withdrawn through the head of the reactor and condensed in an external condenser unit. The stripping of the methanol off the liquid leads to a sharp interface between the glycerol and the ester phase, which can then be easily separated by gravity or pumping. The gas velocity field, pressure field and the liquid particle trajectories were calculated successfully. Simulated dwell time distribution curves were derived and analyzed with the open‐open vessel dispersion model. Experimental dwell time distribution curves were measured, analyzed with the open‐open vessel dispersion model, and compared with the simulated curves. A good consistency between simulated and measured Bodenstein numbers was achieved, but 25 % of the simulated particles exited at the reactor's head, contrary to experimental observations. The difference between simulated and measured dwell times was within one order of magnitude.     

Influence of technological parameters on the epoxidation of 1‐butene‐3‐ol over titanium silicalite TS‐2 catalyst

BACKGROUND: The influence of technological parameters on the epoxidation of 1‐butene‐3‐ol (1B3O) over titanium silicalite TS‐2 catalyst has been investigated. Epoxidations were carried out using 30%(w/w) hydrogen peroxide at atmospheric pressure. The major product from the epoxidation of B3O was 1,2‐epoxybutane‐3‐ol, with many potential applications. RESULTS: The influence of temperature (20–60 °C), 1B3O/H₂O₂ molar ratio (1:1–5:1), methanol concentration (5–90%(w/w)), TS‐2 catalyst concentration (0.1–6.0%(w/w)) and reaction time (0.5–5.0 h) have been studied. CONCLUSION: The epoxidation process is most effective if conducted at a temperature of 20 °C, 1B3O/H₂O₂ molar ratio 1:1, methanol concentration (used as the solvent) 80%(w/w), catalyst concentration 5%(w/w) and reaction time 5 h. Copyright © 2009 Society of Chemical Industry     

Numerical investigation on CO2 absorbed in aqueous N‐methyldiethanolamine + piperazine

A multiphase and multicomponent mass transfer model of CO₂ absorbed in aqueous N‐methyldiethanolamine and piperazine (PZ) was built in the study. In the model, a simple method of mass transfer between phases was proposed. Besides, the hydrodynamics, thermodynamics, and complex reversible chemical reaction were considered simultaneously. The model was validated by comparing with the previous experimental data which showed that simulated results can represent the experimental data with reasonable accuracy. Based on the model, the effects of gas velocity, liquid load and CO₂ loading on the absorption rate, and enhancement factor were analyzed. Model results showed that the enhancement factor increased with a rising gas velocity while decreased with a rising liquid load or CO₂ loading. The change of enhancement factor with CO₂ loading was similar to that of equilibrium concentration of PZ which indicated that PZ was significant to the absorption process. Furthermore, the distributions of specie concentrations were discussed in detail. © 2016 American Institute of Chemical Engineers AIChE J, 63: 2386–2393, 2017     

Modeling and Simulation of a Bubbling SO2 Absorber with Granular Limestone Slurry and an Organic Acid Additive

The absorption of SO₂ into limestone slurry containing suspended reactive particles was performed in a bubble reactor with continuous feeding of both gas and liquid phases at a constant pH and high temperature (50 °C). An absorption model with a reaction plane based on the film model was developed. The effect of limestone particle size, concentration, acetic acid additives, and inlet SO₂ concentration on the concentration distribution of chemical species in the liquid film and SO₂ absorption rate were simulated. Increasing the concentration of limestone slurry, adding acetic acid additives into the system or decreasing the limestone particle size or inlet SO₂ concentration caused the reaction plane in the liquid film to shift towards the gas‐liquid interface. Model and experimental results were compared, and it was shown that the model fits the experimental data well.