Band 11, Heft 1 -

Friedel–Crafts acylation of pyrene with acetic anhydride to 1-acetylpyrene catalyzed by three metal chloride and three Lewis acidic ionic liquids (ILs) containing 1-butyl-3-methylimidazolium chloride ([Bmim]Cl) and different metal chloride was investigated. ILs were prepared and tested for the acylation to explore the effects of Lewis acidity of ILs on the synthesis of 1-acetylpyrene. [Bmim]Cl–FeCl 3 was found to be the most suitable catalyst, and the possible pathway for the acylation of pyrene with acetic anhydride catalyzed by [Bmim]Cl–FeCl 3 -IL was discussed. Pure 1-acetylpyrene was obtained and its structure was identified by gas chromatography–mass spectrometer, Fourier transform infrared and 1 H NMR spectra.

In this investigation, an experimental design procedure using prior literature information has been used to guide the localization of optimal points for reaction kinetics study. Three kinetic models were identified and the Pareto domain was circumscribed for a set of three decision variables and two objective functions to find an optimal solution. From the range of Pareto-optimal solutions obtained, the kinetic model considered to be the most reliable was used to explore the optimal operating region. Finally, the experimental design points were chosen to ensure a sufficient range of operating conditions to identify the reaction kinetics.

A NO x adsorption kinetic model including NO oxidation and adsorption was developed. The NO x and O 2 adsorption experimental data from a fixed bed were found to be fitted well to the Freundlich type isotherm. An axial dispersion adsorption model was then developed to simulate the breakthrough curve for NO x adsorption in the fixed bed. The model parameters including mass transfer coefficient and axial dispersion coefficient were fitted from the NO x breakthrough curves measured in a fixed bed. This model can be used for design and scale-up of fixed bed NOx adsorption columns. It can also be extended for the modeling of NO x adsorption in the annulus region of the circulating fluidized bed reactor for catalytic reduction of NO x .

This paper reports multistep optimization studies on electrochemical (EC) treatment of textile wastewater containing three dyes namely basic orange 30, basic violet 16 and basic green 4 using an aluminum electrode. Chemical oxygen demand (COD) and color removal efficiencies were maximized in a batch EC experimental reactor. In first step, Plackett–Burman (PB) design was used to sort most effective factors amongst the various factors namely current density ( j ), time ( t ), electrode gap ( g ), temperature ( T ), initial pH (pH o ) and NaCl salt concentration ( m ) that affected the removal efficiency. In the next step, steepest accent/descent method and Box–Behnken (BB) design methods were utilized to evaluate the optimum electrochemical conditions. In BB design, three operational parameters, namely j : 117.64–196.07 A/m 2 ; t : 150–210 min and pH o : 3.5–5.5 were taken as input parameter whereas COD removal ( Y 1 ) and color removal ( Y 2 ) were taken as responses of the system. At the optimum operating conditions of j = 185.30 A/m 2 , t 190 min and pH o 5, more than 70.5% COD and 98.2% color removal efficiencies were observed. Field emission scanning electron microscopy of aluminum electrodes, scum and sludge has been carried out to understand the EC mechanism.

Bubble size has a key role in gas holdup and mass transfer in bubble column reactors. In order to have small and uniform bubbles, a new structure was designed; the reactor operates in two modes, with vibrating sparger and conventional bubble column in which sparger is fixed. In vibrating mode, the sparger vibrates gently during gas entering. The vibrating sparger performs like a paddle, resulting in a forced recirculation of gas–liquid inside the reactor; moreover, the bubble detachment is accelerated. The superficial gas velocity was between 0.003 and 0.013 ms − 1 , and the vibration frequency was changed between 0 and 10.3 Hz. The bubble size was measured at three various positions of the reactor height by photographic method and using MATLAB 7.0.1 software. The mass transfer coefficient was determined by means of the dynamic gassing-out method. The results show that the bubbles were bigger in vibrating mode than those working without vibration. The bubble size decreases with increase in height from sparger. Gas holdup increased with increase in superficial gas velocity and vibration frequency. The effect of vibration increased the gas holdup with an average of 70% for all superficial gas velocities. Volumetric mass transfer coefficient was almost stable as vibration frequency increased.

: For an installed silicon-based solar cell panel, about 40% of the energy needed for fabrication is consumed for production of the silicon feedstock. Reducing the energy consumption in this step is therefore crucial in order to minimize the energy payback time and cost of the technology. The most promising alternative to the conventional methods is to use fluidized bed reactors. In this article, we report the results from a novel reactor layout with a selectively cooled distribution arrangement. Important aspects of fludized bed monitoring and operation are described. Two different operation regimes are stated yielding hence porous and dense growth. Further, the method of encapsulating fines by means of more dense depositions is verified, and the nature of the scavenged material is characterized. Also, two different types of fines formation are identified and accounted for.

The reforming of glycerol was investigated using a micro-reactor in the presence of MoCoP/zeolite catalyst. The parameters which were investigated include initial hydrogen pressure, reaction temperature, residence time, and feedstock concentration. The liquid products were separated into water-soluble components and bio-oil by liquid-liquid extraction with water and ethyl acetate. The bio-oil, gaseous products, char, and unreacted glycerol were quantified relative to the initial mass of glycerol feed. The composition of the bio-oil was determined by GC/MS. The optimum conditions for the reforming of glycerol into bio-crude in the presence of MoCoP/zeolite catalyst were found to be: 300°C reaction temperature, 5 MPa initial hydrogen pressure, 60 min reaction time, and 100% glycerol feed. While dilution of the glycerol feedstock with water had a negative effect on bio-oil yield, reforming of pure glycerol produced the highest bio-oil yield (40 wt.% at 300°C, 1 h, and 5 MPa H 2 ). The amount of char deposited on the catalyst decreased with extended reaction time, increased reaction temperature, and elevated initial hydrogen pressure.

The hydrodynamics (gas holdup, Sauter mean bubble diameter, d 32 ) and the overall volumetric liquid-side mass transfer coefficients ( k L a ) were measured in a large-scale (0.29 m ID, 3 m high) slurry bubble column reactor (SBCR) for He/N 2 gaseous mixtures, as surrogates for syngas, in three different Fisher–Tropsch (F-T) products (liquid paraffins mixture, light F-T cut and heavy F-T cut) in the presence and absence of three different solids (spent iron oxides catalyst, alumina powder and Puralox alumina). The effects of pressure (10–30 bar), temperature (up to 500 K), superficial gas velocity (0.14–0.26 m/s), solid concentration (0–20 vol.%) and gas density on these design parameters were investigated. The experimental data revealed that increasing the reactor pressure or gas density increased the gas holdup and decreased d 32 , by increasing the population of the small gas bubbles, which increased the overall k L a values for all the gas mixtures used in the three F-T cuts under most of the operating conditions employed. Increasing temperature increased the gas holdup in the three F-T cuts, except for N 2 -light F-T cut, where the gas holdup values remained almost constant from 400 to 500 K. Increasing the slurry concentration decreased the gas holdup and increased d 32 , mainly for gaseous mixtures with high He mole fractions, which decreased the overall k L a under all conditions used. Increasing the gas superficial velocities ( U G ) increased the gas holdup and k L a values, even though d 32 was found to increase or decrease with increasing U G . Increasing the He mole fraction in the He/N 2 gaseous mixture at constant pressure led to low gas holdup and high d 32 which decreased k L a values, and under similar operating conditions, k L a values of He as a single gas were always lower than those of N 2 as a single gas. Increasing the He mole fraction in the He/N 2 gaseous mixture at constant density, however, was found to have negligible effect on the gas holdup, d 32 and subsequently on the overall k L a . The gas holdup, the overall k L a and the population of the small gas bubbles for N 2 in the liquid paraffins mixture were greater than those in the light F-T cut. Operating the SBCR with the heavy F-T cut resulted in the lowest gas holdup and the largest gas bubbles size which led to the lowest gas–liquid interfacial area and consequently, the lowest k L a values. Also, under the operating conditions investigated, the behavior of overall k L a for the gases used in the three F-T cuts in the presence and absence of the three solids employed was controlled by that of the gas–liquid interfacial area ( a ). Using the data obtained, two novel empirical correlations for predicting the gas holdup and the overall k L a for gases specifically in F-T cuts are proposed.

l -Asparaginase production was investigated in the isolated Aspergillus niger C4 on sesame (black) oil cake using solid state fermentation in a column bioreactor. The main objective of the present study is optimizing the environmental conditions for l -Asparaginase production in a column bioreactor. In order to determine the effect of process variables on the yield of l -Asparaginase, by the way of response surface methodology, an experimental plan (Box–Behnken design) involving a design matrix of 15 trails was sketched. The design results were fitted with response surfaces. Empirical quadratic equations were fitted to the experimental data (BBD) relevant to the yields of l -Asparaginase, with three chosen variables (aeration, bed thickness and temperature). The statistical analysis revealed a maximum l -Asparaginase yield of 310 U/gds at the points where aeration, bed thickness and temperature were 0.44 vvm, 17.35 cm and 29.31°C, respectively.

The paper presents results of kinetic studies on thermal methane combustion over honeycomb monoliths. An analysis of the previous experiments [1] has shown that equations proposed there and their kinetic parameters satisfactorily describe kinetics only for relatively low temperatures up to approx. 700°C. The present study corresponds to that related and supplements the previous data with new kinetic parameters obtained in higher temperatures in the reaction zone up to 900°C. A method of the reaction rate calculation for further simulation studies combining the kinetic parameters obtained in both ranges of low (LT) according to Gosiewski et al. [1] and high temperatures (HT) are also presented in the paper.

A novel approach to identification of fed-batch cultivation of E. coli BL21 (DE3) has been presented. The process has been identified in the system that is designed for maximum production of γ-interferon protein. Dynamic order of the process has been determined by Lipschitz test. Multilayer Perceptron neural network has been used to process identification by experimental data. The optimal brain surgeon method is used to reduce the model complexity that can be easily implemented. Validation results base on autocorrelation function of the residuals, show good performance of neural network and make it possible to use of it in process analyses.

Lignin, a by-product in biorefining industries such as lignocellulose-to-ethanol and paper-making processes, is a promising renewable source for value-added phenolic chemicals. Hydrothermal conversion and fast pyrolysis are two main thermo-chemical approaches for depolymerization of lignin. Hydrothermal conversion is a low temperature (250–500°C) and high pressure (5–30 MPa) process particularly suited for high moisture materials, whereas fast pyrolysis takes place at atmospheric pressure and moderate temperatures in the absence of oxygen and requires drying of the feedstock. In this paper, we present experimental results that provide a comparison of distributions of monomeric phenols produced by fast pyrolysis and hydrothermal conversion of lignin. Hydrothermal conversion experiments were performed in a 150 ml autoclave at 300°C for 30 minutes with different alkaline concentrations. Pyrolysis was carried out in a spouted bed reactor at 500°C. Hydrothermal conversion of lignin under 1 M alkaline solutions resulted in lower char yields (12.1%) compared to fast pyrolysis, which resulted in 54.5% solid yields. Monomer phenols obtained from hydrothermal conversion of lignin were found to have a narrower distribution dominated by catechol and its methyl derivative. In contrast, fast pyrolysis produced a wider distribution of monomeric phenols dominated by guaiacol and its derivatives with various chains substituted para to the hydroxyl group. Mechanisms of lignin fast pyrolysis and the methoxy group conversion under hydrothermal conditions were proposed respectively. In conclusion, hydrothermal technology is better suited for production of value added monomer phenols from lignin.

Dimethyl ether (DME) is traditionally produced by methanol dehydration in an adiabatic reactor. Recently, a more economical method has been proposed to produce DME in a reactor in which methanol production and dehydration take place simultaneously on a bi-functional catalyst. In the present study, the design and optimization of an industrial scale fixed bed reactor for the direct synthesis of DME from syngas are investigated. A steady state, pseudo-homogeneous model has been applied to simulate the proposed reactor. At first, the preliminary design of the reactor is done based on the reactor design heuristics for industrial reactors. Then, using differential evolution (DE) algorithm as a fast and efficient optimization method, the tentative reactor operating conditions and its internal configuration are optimized. The objective of the optimization is to maximize DME production in each tube of the reactor. The number of tubes, feed inlet and coolant water temperatures are considered as decision variables of the optimization algorithm. At the optimum conditions, the reactor size decreases due to increase of CO conversion and DME productivity in each tube. The results show that the proposed optimum reactor is more economical for large-scale production of DME in comparison to the conventional industrial DME reactor.

The key challenge in the operation of any industrial fixed-bed heterogeneous reactor is to enhance the conversion level while keeping the pressure-drop low. Towards this end, the use of finite hollow cylindrical catalyst pellets instead of spherical ones is proposed here. The absence of the pellet core helps to lower the effect of the internal mass transport resistance besides providing a greater surface area. Another equally important advantage is a lower pressure-drop due to the higher bed void fraction associated with hollow pellets. A rigorous model of the heterogeneous fixed-bed reactor containing finite hollow cylindrical catalyst pellet is presented here accounting for the concentration gradients both in the axial as well as the radial directions, thus, resulting in a two-dimensional partial differential equation for the solid catalytic phase.

Most industrial bubble column reactors require the utilization of internal structures for heat transfer and/or for controlling the flow structures and back mixing in the system. The internals denote all types of innards added to a bubble column, such as perforated plates, baffles, vibrating helical springs, mixers, and heat exchanger tubes. In commercial scale bubble columns, instrumentation probes, down-comers, and risers with heat exchangers are all considered. This review presents the state-of-knowledge of bubble columns with internals. It starts with an introduction. The second section discusses the horizontal internals, and the following section examines the studies involving vertical internals.

Fluid catalytic cracking (FCC) is a dominant refining conversion process in China’s most refineries. After decades of development, China has already become one of the major FCC technology licensors in the world. In this review, the research and development (R&D) activities on FCC riser termination device (RTD) technologies in China are reviewed and discussed. Emphasis is put on the R&D of a series of advanced RTD technologies led by China University of Petroleum, Beijing, which initiated in the early 1990s when more and more China’s FCC units chose to process more residue feedstock. Followed by the guideline of three “ quick ”s and two “ high ”s, two early types of RTD systems with coupled zones for gas–solids centrifugal separation and pre-stripping were developed and applied successfully in commercial units. Significantly reduced yields of coke and dry gas due to restrained post-riser reactions and satisfactory particle recovery efficiency were achieved. These were the fender-stripper cyclone and vortex quick separator systems designed for external- and internal-riser FCC units, respectively. Later, further improvement efforts led to the development of another two RTD systems, i.e. the circulating-stripper cyclone system for external-riser units and super vortex quick separator system for internal-riser units. By now, nearly 50 applications were commissioned with a sum FCC capacity of 40.0 Mton/a, nearly one-third of China’s total FCC processing capacity. Besides, other research efforts, such as the geometry optimization efforts on LD 2 type separator, the studies on RTD for down-flow riser FCC units, and the idea of non-disengager FCC unit are also discussed in this review. To accommodate to degraded feedstock, more stringent environmental regulations and new FCC process technologies, future R&D efforts on RTD technologies should be put on improvements to further satisfy the three-“ quick ”s and two-“ high ”s requirements with changing FCC operating conditions and different process requirements.

The spout-fluid bed (SFB) is a very successful synthesis of the spouting and fluidization. The hydrodynamics of SFB are more complex than both fluidized beds and spouted beds. Up-to-date information on the fundamentals and applications of SFBs has been briefly presented, based on the limited work reported, in the new spouted bed book edited by Norman Epstein and John R. Grace (Spouted and spout-fluid beds: fundamentals and applications, 2011). In the past three years, nearly 30 papers have been published in international journals. They reported interesting studies on hydrodynamic characteristics, numerical simulations and new applications of SFBs. This article reviews the major research and development on SFB from the year 2010 and recommends further research topics. This review is intended not only as an important supplement to the SFB chapter of the spouted bed book but also helpful guidance for future research.

CuO/KIT-6 catalyst was prepared by the excess impregnation method, and used for ethanol selective catalytic oxidation to produce acetaldehyde. The properties of the prepared CuO/KIT-6 catalyst were investigated by XRD and TEM. The results indicate that the synthesized CuO/KIT-6 catalyst still retains highly ordered mesoporous structure with well-dispersed CuO species. The CuO/KIT-6 catalyst shows predominant ethanol selective catalytic oxidation activities. The ethanol conversion and acetaldehyde selectivity of the CuO/KIT-6 catalyst at 275°C are 93.8% and 96.6%, respectively. The CuO/KIT-6 catalyst has high ethanol selective catalytic oxidation activity and acetaldehyde selectivity, which can be attributed to the highly ordered mesoporous structure and well-dispersed CuO species.

H 2 O 2 decomposition in the propylene epoxidation system in a fixed-bed reactor was studied herein for the first time. The decomposition rate of H 2 O 2 increased with increasing reaction temperature. The decomposition reaction followed the first-order kinetics equation at 30–50°C, whereas it did not follow the equation any longer at higher than 50°C. A kinetics equation for the H 2 O 2 decomposition catalyzed by TS-1/SiO 2 at 30–50°C was obtained, and the reaction activation energy Ea was calculated as 69.26 kJ/mol.

: A particle population balance formulation for a circulating fluidized bed, involving aggregation and breakage of particles, is solved using the homotopy perturbation method (HPM). The homotopy method deforms a difficult problem into a simple problem, which then can be easily solved. The HPM solution is compared with the solution obtained using a standard finite difference method. Using homotopy, a good approximation of the finite difference solution is obtained within a few iteration steps. The results reveal that the homotopy method is an effective and simple tool to solve nonlinear partial integro-differential equations and has a wide scope and applicability to solve complex engineering problems. The reliability of the algorithm is tested using three different feed inlet particle size (diameter) distributions to indicate the robustness of this method.

A quantity of steel rolling sludge (SRS) produced in the rolling mill is harm to the environment and difficult to dispose. This article is devoted to study on utilization of SRS in sintering process. A sinter pot system with capacity of 75 kg was established. The sintering time, the flue gas temperature, the sintering temperature and the suction pressure in sintering process were measured. Besides the sinter quality, air pollutants discharged from the sintering process with the mass fraction of SRS ranging from 0 to 3% was investigated. The results showed that the CO 2 concentration is corresponding to the sintering process, the SO 2 concentration has a self-sustaining characteristic and the NO X concentration maintains stability. Increase in mass fraction of SRS leads to the decrease of sintering temperature, particle size, tumbler index and basicity of the sinter. Besides, the sintering time and the average concentration of NO X decrease first and then increase, while the suction pressure appears an opposite trend with increasing mass fraction of SRS. Moreover, the average concentration of CO 2 and SO 2 both decrease with increasing mass fraction of SRS, and the fuel consumption per sinter produced is the least when the mass fraction of SRS is 2%. Therefore, when the mass fraction of SRS was 2%, the sintering process had the best performance in consideration of sinter quality, emission of air pollutants and behaviors in sintering process.

Modeling and optimization of the process of continuous catalytic reforming (CCR) of naphtha was investigated. The process model is based on a network of four main reactions which was proved to be quite effective in terms of industrial application. Temperatures of the inlet of four reactors were selected as the decision variables. The honey-bee mating optimization (HBMO) and the genetic algorithm (GA) were applied to solve the optimization problem and the results of these two methods were compared. The profit was considered as the objective function which was subject to maximization. Optimization of the CCR moving bed reactors to reach maximum profit was carried out by the HBMO algorithm and the inlet temperature reactors were considered as decision variables. The optimization results showed that an increase of 3.01% in the profit can be reached based on the results of the HBMO algorithm. Comparison of the performance of optimization by the HBMO and the GA for the naphtha reforming model showed that the HBMO is an effective and rapid converging technique which can reach a better optimum results than the GA. The results showed that the HBMO has a better performance than the GA in finding the global optimum with fewer number of objective function evaluations. Also, it was shown that the HBMO is less likely to get stuck in a local optimum.

A user-friendly simulator based on a comprehensive computer model for slurry bubble column reactor (SBCR) was used to predict the performance of a conceptual commercial-scale (9-m ID and 50-m height) SBCR for Fischer–Tropsch (F–T) synthesis. Novel correlations for predicting the hydrodynamic and mass transfer parameters; a new relationship between the axial dispersion of large gas bubbles and their average diameter; and up to ten different kinetic rate expressions available in the literature for iron and cobalt-based catalysts were included in the simulator. The effects of operating conditions, including catalyst concentration, pressure, temperature, H 2 /CO ratio, and superficial gas velocity on the SBCR performance were predicted using the simulator for both types of catalysts. The predictions showed that the performance of the reactor was strongly dependent on the type of catalyst and the kinetic rate expression used.

Computational fluid dynamics (CFD) technique was employed to study solids suspension in a stirred tank equipped with three side-entering impellers. Simulations of solid–liquid flow were performed by using an Eulerian-Granular Multiphase (EGM) model coupling with standard k – ε mixture turbulence model and Reynolds stress model, respectively. A multiple reference frame (MRF) approach was used to model the impeller rotation. The CFD predictions have been verified by comparing the predicted results with the experimental just suspended impeller speed and solid sediment pattern at the tank bottom. The solid distribution and liquid-phase velocity vectors throughout the tank for two cases with and without solid phase were investigated to understand the characteristics of solid–liquid flow. The solid suspension quality has been assessed by employing three criterions: the just suspended impeller speed N js , cloud height h , and suspension homogeneity. The effects of impeller agitation speed, particle size, and solid loading on suspension quality have been investigated. The computational model and results discussed in this study would be useful to understand the solid–liquid dispersion process in side-entering stirred tanks and extend the application of CFD models for equipment design and process optimization.

The oxidation reaction of 2-ethyl-1-hexanol with potassium permanganate in the presence and absence of silica-gel-supported phase-transfer catalyst (PTC) in triphasic conditions was studied. In a batch reactor, the performance of the solid-supported catalysts was compared with unsupported catalyst and without the catalyst. The effect of speed of agitation, catalyst concentration, potassium permanganate concentration and temperature on reaction rate was studied. The reaction is found to be in the kinetic regime. The rate of reaction with the catalyst immobilised on the silica gel was less compared to the catalyst without immobilisation. Triphase catalysis with supported PTCs has potential applications in the continuous quest for greener industrial practices.

The lanthanum manganite perovskites with excess Mn and La partially substituted with alkaline earth metals including Mg, Ca, Sr, and Ba were used for oxidation of trichloroethylene (TCE). Ba-substituted perovskite shows highest TCE oxidation performance. Twenty percent of excess Mn and La substitution with Ba up to 30% (La 0.7 Ba 0.3 Mn 1.2 O 3+ δ ) resulted in a high Brunauer, Emmett and Teller (BET) surface area and enhanced oxygen mobility. About 12% loss of the performance of La 0.7 Ba 0.3 Mn 1.2 O 3+ δ is observed during the first 20 min, and then a steady-state conversion is established for oxidation of TCE for 10 h. The perovskite structure is not destroyed after deactivation test, and loss of surface area may be responsible for the initial performance decline.

The article presents a novel microwave reactor for hydrothermal synthesis of nanopowders. The reactor has a unique design of a process chamber, which, when used in conjunction with a batch control system, allows a highly efficient production of nanopowders. The design of the reactor together with the new principles of operation, structural materials and distribution of electromagnetic field are described. The article also presents a control system for the reactor, which allows for an automatic operation in the stop–flow mode, control of process pressure, continuous monitoring of process parameters and safe operation of the device. The device verification process is shown on the basis of the results of cobalt-doped zinc oxide nanopowder synthesis.

This work presents the hydrolysis of a water-soluble protein, bovine serum albumin (BSA), for the production of both amino and organic acids under the sub-critical water condition in the temperature range of 200–300°C. The products of the reaction were a water-insoluble solid phase, an aqueous phase, and an insignificant gas phase which was neglected in this study. Results have shown that BSA passes through an aggregation step, followed by a gel formation process which results in the formation of insoluble solid aggregates. Then, such formed solids unfolded with releasing polypeptides as an intermediate product then finally hydrolyzed to produce low molecular mass products such as amino and organic acids. It was found that there were insignificant amino acids produced in the temperature ranges of 200–225°C within 2 min and 275–300°C within 0.5 min. However, by extending the reaction time, the protein transferred to both amino and organic acids.

The objective of this study was to purify glycerine obtained from the transesterification of cottonseed oil, using ion exchange resins. The batch process used strong cation, weak anion and a mixture of its resins. The purified glycerine was characterized as to metal content, colour and glycerol content. The experiments were conducted using the resins individually and in series. In the experiments in series, there was a constant decrease in conductivity. Analyses without the use of charcoal showed that conductivity behaved similarly to that of treatment with charcoal. For conductivity tests using activated charcoal and individual resins, the mixed resin produced the best result when compared to commercial glycerine.Considering the analysis made with activated carbon, when the glycerine solution was treated with individual resins, it was observed that the conditions established for treatment with 10 g of resin, 5 hours of contact with each resin and 50 mL of glycerine, its conductivity decreased to the cation exchange resin, increased to anionic resin and had a variable value with respect to the mixed resin. In serial processing, there was a steady decrease in the conductivity of the glycerine solution. The content of glycerol, after the solution had been passed through activated charcoal, 56% of the compound was recovered. It was also observed that the mixed resin retained a lower amount of glycerol. It can be concluded that ion exchange resins were efficient in treating the glycerine solution in all the tests, since there was little glycerol retention and high undesirable compound retention.

The droplet–gas flow in effervescent atomization was simulated using a comprehensive numerical model. Liquid film thicknesses in the nozzle exit orifice and droplet size distribution at the downstream of spray were calculated. The thickness of liquid film in the nozzle exit orifice increased and approached the droplet size in the primary atomization, as the air–liquid ratio increased. The primary breakup model can accurately predict the Sauter mean diameter in the primary atomization when gas–liquid two-phase flow belongs to the annular flow in the nozzle exit orifice. The viscosity of fluid had minimal influence on the liquid film thickness for spray with fluids, the viscosity of which is significantly greater than that of water. Droplet size initially decreased and then increased along the axial distance because of the secondary atomization and droplet coalescence at the downstream of spray.

In this paper, we report loading of ZnCl 2 on microporous medium pore high surface area zeolite, which was achieved by incipient wetness method. The zinc-modified mobil composite material -22 (Zn-MCM-22) was systematically characterized by powder X-ray diffraction, N 2 adsorption-desorption analysis, scanning electron microscopy and Fourier transform infrared spectroscopy. The acidity of the materials was studied by temperature programmed desorption of ammonia analysis. The well-characterized Zn-MCM-22 catalyst was investigated for the Friedel–Crafts alkylation of benzene by benzyl chloride in liquid phase medium. A systematic investigation of various operating parameters like effect of different temperature, catalyst loading and reactant molar ratio was carried out. The Zn-MCM-22 found to be promising, further the catalytic activity remains stable over several recycles.

This article put emphasis on systematic research and development on cellulose hydrolysis reactor. The simultaneous saccharification and fermentation of lignocellulosic was carried out in a 5-L reactor at high solids loading of corn stover (25%, w/w). The dynamic characteristics of reactive system were examined. The experimental results showed that the lignocellulosic biomass experienced a series of morphology evolution and viscosity variation. This evolution was a typical event caused by solid reactive processing, and it constituted the basis of a new geometrical configuration of reactor (specifically hybrid impeller). The minimum rotational speed of the impeller was proposed based on the Coutte flow analogy and the yield stress concept. The macroscopic performance of the reactor changed significantly with time. In view of this effect, the operating strategy of the impeller was determined.

Due to the disgusting smell of light mercaptans, researchers are not interested in working with them, so there is not enough information available on their kinetics. This work presents kinetic investigation of oxidation of ethyl, normal-propyl, iso-propyl, and iso-butyl mercaptans in the presence of Merox catalyst. The results demonstrated that the oxidation rates of all mercaptans were first-order reaction with respect to mercaptan concentration, and the increase in NaOH concentration reduced the oxidation rate. While it was observed that there was a similarity between oxidation pattern of iso-propyl and ethyl mercaptans, another similarity was discovered between normal-propyl and iso-butyl mercaptans.

Feed-forward neural network (FFNN) modeling techniques are applied to study the flow behavior of different-size irregular-shape particles in a pilot scale liquid–solid circulating fluidized bed (LSCFB) riser. The adequacy of the developed model is examined by comparing the model predictions with experimental data obtained from the LSCFB using lava rocks ( d mean 500 and 920 µm) and water as solids and liquid phases, respectively. Axial and radial solid holdup profiles are measured in the riser at four axial locations ( H 1, 2, 3 and 3.8 m above the distributor) above the liquid distributor for different operating liquids. In the model training, the effects of various auxiliary and primary liquid velocities, superficial liquid velocities and superficial solid velocities on radial phase distribution at different axial positions are considered. For model validation along with other experimental parameters, dimensionless normalized superficial liquid velocities and net superficial liquid velocities are also introduced. The correlation coefficient values of the predicted output and the experimental data are found to be 0.95 and 0.94 for LR-500 and LR-920 particles, respectively which reflects the competency of the developed FFNN model.

The translational and rotational motions of biomass particle in a spout-fluid bed have been investigated. Two kinds of cylindrical biomass particles with different densities were used as bed solids, which were obtained from the jujube tree. To describe the translational and rotational characteristics, virtual particle concentration and rotation angle were introduced. The former obtained by microwave heating-infrared thermal imaging technique was compared with the actual particle concentration determined by box-counting method. Based on the temperature distribution, the translational position and rotation angle of multiple tracers were distinguished. The results show that the heating characteristic of tracer depends on the tracer material. Compared to the spherical particles, non-spherical biomass particle is more likely to cause dead zone in the bed. In the flow regime of fluidizing, the flow characteristic of biomass particle relies on the jet gas velocity. The high resistance resulting from the interparticle cohesion forces hinders the rise of bubbles and weakens the radial dispersion of particle. In the fountain, homogeneous biomass particle rotates uniformly, while non-homogeneous biomass particle exhibits non-uniform rotation. In the annulus, the rotation characteristic of biomass particle depends on the structure of fountain and particle trajectory in the annulus.

In this study, a detailed rigorous kinetic model is proposed for the industrial production of methanol taking into account changes in total mole flowrate. The kinetic model proposed is compared with the one proposed in literature (Rezaie et al., Chem Eng Process Process Intensification 2005;44:911–21), showing significant differences in terms of compositions and total mole flow. A complete simulation of the methanol production process is developed with a commercial software. The rigorous reactor model is integrated in the simulation using the CAPE OPEN standard. Flowsheet simulation is carried out, and results show small differences with those found in previous studies (Luyben, Ind Eng Chem Res 2010;49:6150–63).

Co-pyrolysis characteristics of lignite and rice husk blend were determined in TGA and a fixed-bed reactor. From TGA results, the weight loss rate of lignite and rice husk blend increases at 250–400°C. In a fixed bed at programmed temperature condition, the synergistic effect to produce more volatiles is appeared at 500–700°C, and the maximum synergistic effect exhibits with a rice husk blending ratio of 0.8. The gas yield of co-pyrolysis of lignite and rice husk blend was higher than that of the sum of lignite and rice husk individually. The kinetic studies were performed according to Coats–Redfern method for first-order reaction. It was found that the pyrolysis process of lignite and rice husk could be described by one first-order reaction and two consecutive first-order reactions, respectively. However, for lignite and rice blends, this process can be described by three consecutive first-order reactions. The estimated kinetic parameters, viz., activation energies and pre-exponential factors for lignite, rice husk and their blends, were found to be in the range of 63.5–477.8 kJ/mol and 1.4 × 10 3 –6.5 × 10 47 min −1 , respectively.

Hydrogen production by oxidative steam reforming of methanol in a fixed bed catalytic reactor was modeled and simulated. The addition of O 2 to feed reduced the temperature in the reformer. 99.86% conversion was obtained at 550 K and S/C molar ratio of unity in steam reforming while it is at 540 K in oxidative steam reforming. Although H 2 and CO yields were decreased in oxidative steam reforming in comparison to steam reforming, the reductoin H 2 yield was note significant whereas reduction in CO was appreciably high. The thermal and exergy efficiencies were favored by reforming temperature and S/C molar ratios. However, variation in S/C molar ratio showed negligibly small effect on efficiencies. The reforming temperature had a notable influence on the efficiencies. The exergy destruction was found to be lower at higher temperature and S/C molar ratio. Thus, oxidative steam reforming of methanol at 540 K and S/C molar ratio of unity utilizes sufficient amount of input energy in the form of useful work and thermodynamic irreversibilities in the reactor are quantitatively small.

Genetically modified crops, which produce insecticidal toxins from Bacillus thuringiensis ( Bt ), release the toxins into soils. Although the phenomena of persistence and degradation of Bt toxins have been documented, the effect of heavy metals on the fate of these toxins in soil has not yet been elucidated. The effect of Pb(II) on the adsorption behaviors of Bt toxin in brown and red soil was investigated. With the increase of Pb(II) concentration, the adsorption of Bt toxin in brown and red soil increased. The Langmuir, Freundlich and Dubinin–Radushkevich (D–R) isotherm models gave better fitting to the experimental equilibrium data. Values of K L , K F and n increased but R L decreased with the increase of Pb(II) concentration, showing that the Pb(II) promoted the adsorption of Bt toxin in soils. The mean free energy of adsorption ( E ) ranged from 10.43 to 16.44 kJ mol −1 may correspond to a chemical ion-exchange mechanism. Three kinds of kinetic models, the pseudo-first-order, pseudo-second-order and intraparticle diffusion model, were used to test the experimental data. The results showed that the adsorption of Bt toxin by brown and red soil followed the pseudo-second-order kinetic model. The addition of Pb(II) during the adsorption led to a decrease of the desorption of Bt toxin from soils, indicating that the residual risk of Bt toxin may become larger if soil is polluted by lead.

This work analyzes carbon dioxide mass transfer rate during chemical absorption from a gas phase to a liquid–liquid system based on an aqueous phase (glucosamine or pyrrolidine solutions) and an organic one. Two different kinds of silicone oil with different viscosity were used to perform the liquid phases, and it allows the analysis of the influence of this variable upon mass transfer rate. In these systems, a surfactant (Tween80) was added to stabilize the liquid–liquid system, and therefore, the influence of the presence of this surfactant in the liquid phase was studied. This substance produces a positive effect upon carbon dioxide absorption rate in glucosamine aqueous solutions, but the opposite effect was observed for the other amine employed in this work. Also, the influence caused by different operation variables, such as the gas flow-rate fed to the bubble contactor or the silicone oil concentration in the liquid phase, was studied.

The composition of feed water used in electrodialysis (ED) desalination causes the risk of CaCO 3 scale crystallization in ED equipments, which leads to the decrease of process efficiency. To control scaling in water systems, several scaling indices and tests, permitting to predict the scaling occurrence, have been devised. In this study, an accelerated scaling test allowing to follow CaCO 3 formation in water desalination plant using ED process was proposed. Tests were performed using a pilot unit as a conventional ED in batch recirculation mode. By simple in situ measurements of pH and flow rate of the concentrate, the crystallization onset and growth of CaCO 3 were followed during the pilot operation. This leads to precise determination of the number of concentrate recirculation times and therefore to the highest recovery rate without scaling risk as a function of the inlet water quality and the antiscale pretreatment.

The selective oxidation of ammonia to hydroxylamine using titanium silicalite-1 as a catalyst with an increasing content range of 1–2.5 wt% TiO 2 was systematically investigated in a batch reactor. The hydroxylamine yielded 33, 43, 52 and 62% at reaction temperatures of 50, 60, 70 and 80°C, respectively, for 8 min using a TS-1a catalyst, which contained 2.5% TiO 2 . The molar ratio of 15 NH 3 /H 2 O 2 was kept during these reactions. Experiments were also conducted with different amounts of NH 3 /H 2 O 2 in molar ratios, which were between 7 and 60 to investigate the effect of NH 3 /H 2 O 2 molar ratio on the reactions. Reactions with higher ratios of NH 3 /H 2 O 2 were seen to have a higher yield at the end of the reaction performance time.

NO reduction to N 2 is the key reaction for efficient operation of a three-way catalytic converter (TWC). It is reported that metal catalysts Pt and Rh co-exist as individual metals in a TWC to give synergistic performance. In this article, we have studied the NO + CO reaction for a 1:1 physical mixture of silica supported Pt and Rh catalysts using fixed bed experiments and microkinetic modeling. The microkinetic model [14] for the reaction on single metals Pt and Rh is simulated for the mixture case in CHEMKIN PRO ® . It is observed that the mixture maintains the activity while producing less N 2 O (by-product of NO + CO reaction) thus enhancing N 2 selectivity inspite of having only half amount of Rh. Analysis of surface coverages on individual metals in mixture shows that in the presence of Pt, CO poisoning of Rh is reduced at lower temperature leading to better overall conversion and selectivity. This has potential benefit in automotive catalysis, as it results in the formation of significantly lower amounts of N 2 O, an undesirable side-product and greenhouse gas; at a lower cost than if pure Pt/Rh catalysts were used.

This study deals with a detailed numerical investigation of the microwave heating process in plastic pyrolysis. The pyrolysis of high-density polyethylene (HDPE) was studied using a single-mode microwave cavity, TE10 mode, at 2.45 GHz with two different absorbents, as carbon and silicon carbide, and the results were compared. The temperature distribution inside the sample was determined by solving the conservation equations coupled with the microwave and chemical kinetic equations. Lambert’s law was applied to describe the electromagnetic field in the microwave cavity. The effective heat capacity method was used to account for the latent heat in the melting range of plastic. The heat of the reaction was taken into account using first-order kinetic equations assuming a single-step reaction. One-dimensional model equations were solved using the finite difference method utilising MATLAB codes. The model developed in this study provides a better understanding of the fundamental mechanisms of the microwave pyrolysis of HDPE based on a combination of electromagnetic field and thermal models. The primary focus was to incorporate and investigate the effect of the phase changes and reaction during microwave pyrolysis. The results show that the temperature profile strongly depends on the physical properties of the material. Silicon carbide provides more uniform heating distribution compared with carbon.

Using titanium dioxide, photocatalytic degradation of waste water polluted by commercial mercaptans (80% t -butyl mercaptan and 20% methyl ethyl sulfide) was investigated in a continuous photoreactor in the presence of UV irradiation. The reaction was performed at different pH of solution, intensity of irradiation, and initial concentration of odorant. Kinetics and mechanism of photocatalytic decomposition of mercaptans were studied by ex situ FTIR measurements of intermediates. The results showed that the photocatalytic process for degradation of mercaptans was an efficient method for mineralization of sulfur odorants in waste water. A proposed mechanism of mineralization of mercaptan was presented based on the results.

Batch experiments were carried out for the adsorption of oxytetracycline (OTC) onto powdered activated carbon (PAC). The operating variables examined were the initial concentration (20–150 mg L −1 ) and the adsorbent concentration (0.75–1.75 g L −1 ). As observed increasing the initial concentration, while decreasing the adsorbent dosage, had a positive impact on the amount of OTC uptake (mg g −1 ). The kinetics was examined in a closed-loop fixed bed adsorber to propose an adsorption mechanism, to understand the dynamic interactions of OTC with ECA08 activated carbon and to predict its fate with time. The sorption results were analyzed using chemical and physical kinetics models. For concentrations lower than 70 mg L −1 , the sorption process was found to be controlled by both surface reactions and mass transfer. The average external mass transfer coefficient and intraparticle diffusion coefficient were found to be 0.0051 min −1 and 1.97 mg g −1 min −0.5 , respectively. For concentrations higher than 70 mg L −1 , mass transfer became rapid and the chemical reaction at the surface of the solid phase was the rate-limiting step. The results showed that the adsorption reaction was accurately described by the pseudo-second-order model.

A Ce 0.86 Cu 0.14– x O 2 catalyst was prepared by the citric acid complex method and characterized by X-ray diffraction, scanning electron microscopy, and temperature-programmed reduction, and its activity in the catalytic wet peroxide oxidation of 4-chlorophenol (4-CP) and 2,4-dichlorophenol (2,4-DCP) was investigated. The results showed that the Cu 2+ ions dissolved into the CeO 2 lattice to form a Ce 0.86 Cu 0.14– x O 2 solid solution with a coarse, interconnected, porous, and cotton-like morphology. The metal–oxygen bonds were weakened by solid-solution formation in the Ce 0.86 Cu 0.14– x O 2 catalyst. This weakening facilitated H 2 O 2 activation and decomposition to form highly oxidative HO ∙ species that can lead to significant chlorophenol mineralization. A total organic carbon removal rate greater than 80% was achieved after 2 h reaction at 50°C and at an initial 4-CP and 2,4-DCP concentration of 50 mg/L. The effects of H 2 O 2 dosage, catalyst dosage, and initial chlorophenol concentration on catalytic efficiency were also determined.

This work analyses the influence of different experimental conditions over important hydrodynamic parameters of a bubble column reactor, such as bubble size distribution, gas hold-up and the gas–liquid interfacial area. The influence of gas flow-rate (18–40 L h –1 ) and reagent concentration (0–0.5 mol L –1 ) in the liquid phase upon these hydrodynamic parameters have been studied. The influence of experiment time must also be taken into account due to non-steady-state regime. Under these considerations, the chemical absorption rate changes throughout time, and it produces important changes upon the global absorption process, due to modifications in the gas–liquid interfacial area. The presence of a fast reaction in the liquid bulk has the highest influence upon interfacial area.

In this paper, it was aimed to study the removal of 4-nitrophenol (NP) from aqueous solution by adsorption using granular activated carbon (GAC); and in sequencing batch reactor (SBR) without any adsorbent (blank-SBR) and with an SBR loaded with GAC (GAC–SBR). During adsorption study with GAC, effect of pH, adsorbent dose ( m ) and contact time ( t ) were studied. Adsorption isotherm, kinetic and thermodynamic parameters were determined. During NP removal in SBR, effect of hydraulic retention time (HRT), initial concentration ( C 0 ) and m were studied. The percent removal in case of GAC–SBR was found to be greater in comparison to blank-SBR. The removal of NP from blank-SBR and GAC–SBR for C 0 of 35, 65 and 100 mg/l was found to be 90.46% and 91.23% ( m =2 g/l); 52.33% and 96.05% ( m =2.5 g/l); 20.01% and 92.72% ( m =2.5 g/l), respectively.

Lipase-mediated, ultrasound-assisted synthesis of poly-ε-caprolactone was investigated. It was found that ultrasound irradiation helped to improve the rate constant of poly-ε-caprolactone chain propagation ( k p ) at high initial monomer (ε-caprolactone) concentration. The enhancement of k p ranged from 34% to 46% at 22.5–18.0 M initial monomer concentration, respectively. In a system proned to time-dependent mass-transfer limitation due to polymer chain extension, the acoustic effects could have also allowed the reaction to continue longer compared to non-sonicated process until it became impossible at highly elevated reaction mixture viscosity(>2,000 times increase from initial viscosity). Consequently, it also helped to improve monomer conversion. In a continuous flow polymerization system, a plug flow reactor system is recommended due to its lowest volume for maximum conversion compared to a continuously stirred tank reactor system.