bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of partial poisoning of acid sites on selectivity in the multiple reactions of mono‐substituted‐t‐Butylbenzenes
Authors: Takahashi Takeshige , Kuramoto Kenji , Kai Takami , Tashiro Masashi 
Published: March 2009

AbstractThe decomposition reaction of p–t‐butylcumene and t‐butylbromobenzene have been carried out over pyridine poisoned silica‐alumina and HY zeolite in order to examine the effect of acid strength on selectivity.Since the catalyst deactivation rate for isomerization over the poisoned silica‐alumina was greater than that of de‐t‐butylation in the reaction of p–t‐butylcumene, the selectivity of de‐t‐butylation gradually improved with process time.In the reaction of t‐butylbromobenzene over poisoned HY zeolite, the de‐bromination rate was suppressed by the poisoning because the nature of active sites was different between silica‐alumina and HY zeolite. The poisoned HY zeolite was found to be favorable for the de‐t‐butylation of halogenated‐t‐butylbenzenes.
Thermodynamic aspects of the utilization of coal‐based raw materials within the system of the petrochemical industry
Authors: Sokić Milorad , Cvetković Ružica , Trifunović Zoran 
Published: March 2009

AbstractThe system of processes for producing olefins and aromatics was investigated in order to assess the thermodynamic aspects of the substitution of actual petrochemical raw materials by coal.As coal conversion technologies offer several alternative processing routes for the production of olefins and aromatics, a mathematical model of the system was used to generate the optimum, as well as suboptimum system structures, with respect to the objective of efficient energy utilization, expressed as the minimum total lost work rate.The relative importance of direct, as well as indirect, coal liquefaction processes was discussed considering both raw materials and energy utilization efficiency.
Zinc electrowinning with 2‐butyne‐1,4‐diol
Authors: Piron D. L. , Mathieu D. , D'Amboise M. 
Published: March 2009

AbstractThe beneficial effect of 2‐butyne‐1,4‐diol on zinc current efficiency in the presence of nickel impurity has been examined. Several techniques including HPLC, absorption spectrophotometry and constant current deposition experiments have shown that a trimer of 2‐butyne‐1,4‐diol is responsible for the removal of Ni ions from the electrolyte, thus increasing the current efficiency of the zinc electrowinning process from sulphate solutions (60 g/L Zn + 200 g/L H2SO4) in the presence of Ni ions.
Gas‐liquid mass transfer in “dead‐end” autoclave reactors
Authors: Chaudhari R. V. , Gholap R. V. , Emig G. , Hofmann H. 
Published: March 2009

AbstractGas‐liquid volumetric mass transfer coefficients, (kLa), have been obtained for “dead‐end” autoclave reactors operated in two different modes: (a) gas introduced into the gas phase, and (b) gas introduced through a dip‐tube in the liquid. Three different methods of kLa determination have been compared. Effects of agitation speed, impeller diameter, gas to liquid volume ratio (Vg/VL), position of the impeller and reactor size on kLa have been investigated. The kLa data were found to be correlated as:kLa = 1.48 × 10−3 (N)2.18 (Vg/VL)1.88 (dI/dT)2.16 (h1/h2)1.16The critical speed of surface breakage, at which transition from the surface convection to the surface entrainment regime occurs, was also determined for different impeller positions, impeller diameters and gas to liquid volume ratios.
Axial dispersion, holdup and flooding characteristics in pulsed extraction columns
Authors: Yu Yong‐Ho , Kim S. D. 
Published: March 2009

AbstractThe effects of interactions between the perforated and baffle plates, of pulse amplitude and of pulse frequency on axial dispersion in the continuous phase, on the dispersed phase holdup and on the flooding condition have been determined for a 10.2 cm 1D pulsed extraction column. The axial dispersion coefficient increased with both the pulse amplitude and the frequency, but it decreased with the decrease in baffle spacing in the unit module. Dispersed phase holdup increased with the number of perforated plates in the unit module at the lower pulsation velocities and increased with the pulse velocity. The baffle plate reduced the total throughputs, but baffle spacing did not have any significant effect on the total throughput.
Oxygen‐steam gasification of coals in a spouted bed
Authors: Watkinson A. P. , Cheng G. , Lim C. J. 
Published: March 2009

AbstractA bituminous and a sub‐bituminous coal from Western Canada have been gasified in oxygen‐steam and air‐steam mixtures in a 0.30‐m diameter, 50 kg coal/h continuous spouted bed reactor. Results are presented to show the effects of the blast composition and reactor temperature on gas heating value and carbon conversion. Operation in the ash agglomeration mode is illustrated, and the role of K2CO3 as catalyst explored. Results from a wide range of experimental gasification conditions are compared with predictions of an equilibrium model.
Application of orthogonal collocations to some transport phenomena problems in co‐axial cylinders and spheres
Authors: Goyal S. K. , Esmail M. N. , Bakhshi N. N. 
Published: March 2009

AbstractCollocation methods are developed for the solution of some differential equation models for transport phenomena problems in one‐and two‐dimensions in co‐axial annuli of spherical and cylindrical shapes. General formulae are developed to obtain orthogonal polynomials over an arbitrary interval using two types of weighting functions. The convergence and accuracy of the methods are demonstrated using two test problems, i.e., calculation of effectiveness factors in (a) a spherical pellet with peripherally deposited catalyst and (b) a Raschig ring type cylindrical catalyst pellet. Comparisons of results obtained from the present methods with analytic solutions for the first‐order reactions indicate good agreement. Numerical solutions are also obtained for the second‐and the third‐order reactions for which analytic solutions are not available. Results obtained in terms of a new Thiele modulus involving the ratio of volume of peripherally deposited part of catalyst to exterior surface area indicate that this normalization brings effectiveness factor versus Thiele modulus curves close together for co‐axial spherical and long cylindrical pellets, as it does for these geometries without the inner co‐axial portion.
Modélisation et simulation de la décomposition catalytique du méthanol dans un réacteur à lit fixe
Authors: Thérien Normand , Tessier Patrick 
Published: March 2009

AbstractUn modèle à paramètres distribués représentant le comportement dynamique d'un réacteur tubulaire catalytique dans lequel a lieu une réaction endothermique de décomposition du méthanol en hydrogène est présenté. Les prévisions obtenues tant au niveau thermique qu'au niveau cinétique, en régime permanent et en régime transitoire ont été comparées à des résultats expérimentaux et montrent l'aptitude du modèle à reproduire les comportements du réacteur étudié. Une étude de sensitivité a permis de montrer l'importance de certains paramètres du modèle sur les résultats.
The fischer—tropsch synthesis over a ruthenium catalyst under composition cycling
Authors: Ross Gerald S. , Hudgins R. R. , Silveston P. L. 
Published: March 2009

AbstractThe influence of feed composition cycling on the activity and selectivity of the Fischer‐Tropsch synthesis over an alumina‐supported ruthenium catalyst was investigated using a fixed‐bed reactor at 211°C and 446 kPa total pressure. Forced composition cycling suppressed the overall synthesis rate but increased the rates of formation of the C1 to C4 paraffins and shifted the paraffin/olefin ratio.
An analysis of simultaneous absorption of two gases reacting between themselves in a semi‐batch reactor
Authors: Bhattacharya A. , Chaudhari R. V. 
Published: March 2009

AbstractThe problem of simultaneous absorption of two gases reacting between themselves in a semi‐batch reactor has been analysed. An exact analytical solution for the enhancement factor has been obtained which requires neither a prior knowledge of the regime of absorption nor arbitrary choice of bulk liquid phase concentrations of gaseous reactants. The methodology developed here can easily be extended to a continuous flow reactor.
Distinctive burning characteristics of carbon particles
Authors: Annamalaim K. , Caton J. A. 
Published: March 2009

AbstractSeveral reaction mechanisms exist in the literature for the gasification of char/carbon particles. The general procedure for modelling particle gasification is to assume a mechanism of combustion, obtain the theoretical burning rate and particle temperature, and then validate the mechanism by comparing the results with experimental data. The present work shows that the burning rate and particle temperature are independent of heterogeneous and homogeneous reaction mechanisms and their rate kinetics as long as the oxygen (O2) and carbon dioxide (CO2) concentrations at the burning surface are low compared to carbon monoxide (CO) concentration. Experimental data are cited which are in agreement with the model's predictions for both particle temperatures and burning times. The relevance of the results to industrial combustors is discussed.
Frictional loss in multiplate bubble columns
Authors: Chen B. H. , Wakao N. 
Published: March 2009

AbstractGas holdup and pressure loss were measured for various gas‐liquid systems in a batch, multistage bubble column. Experimental results show that the use of screen plates (α = 0.64) considerably increases the gas holdup but introduces a significant pressure loss for the two‐phase mixture. The pressure loss was found to be independent of physical properties of the mixture, and predictable either from the modified separated flow model (Chen et al., 1986) or from the kinetic energy loss based on the liquid circulation velocity.
Drop size distribution in a liquid‐liquid spray column via a photographic technique
Authors: Lin F. , Ford J. D. 
Published: March 2009

AbstractA photographic technique was devised for obtaining drop size distribution in a liquid‐liquid (kerosene‐water) spray column. Drop sizes were determined with the aid of a reference ball, using a double‐flash technique with side lighting. Experimentally analyzed Sauter mean diameters were in good agreement with those predicted by the Kumar and Hartland correlations. The technique was applied up to a holdup of about 6% in this countercurrent flow study
Boundary element prediction of the free surface shape between two particle plugs in a horizontal pneumatic transport pipeline
Authors: Konrad K. 
Published: March 2009

AbstractA method is presented to predict the shape of the gas‐particle interface between two plugs of cohesionless particles conveyed pneumatically through a horizontal pipeline. The method assumes that the moving solids are limiting equilibrium at the interface and that, therefore, the interfacial slope depends on the normal pressure gradient which can be used as a boundary condition for the numerical solution of Laplace's equation. The height of stationary material between the plugs cannot be predicted by the method, since this material is not in a state of limiting equilibrium. However, an analogy with a gas‐liquid system can be used to predict this height. The method as presented is restricted to plugs of constant voidage and to systems which obey Darcy's law (packed bed Reynolds numbers less than 10). The boundary element numerical technique is used to apply the method to a 2‐dimensional example of flow through a 50 mm I.D. pipe. The predictions are qualitatively in agreement with photographs of the observed shape in the true (3‐dimensional) situation. However, further numerical and experimental work on the 3‐D situation is required for a full assessment of the proposed method.
Mass transfer characteristics in a gas–liquid reciprocating plate column. II. Interfacial area
Authors: Veljković Vlada , Skala Dejan 
Published: March 2009

AbstractThis paper is the second part of a continuing study on mass transfer in a reciprocating plate column. The first part dealt with kLa. The bubble size distribution, the Sauter mean diameter and the interfacial area are the subject of this paper.The bubble size increases slightly with gas flow rate and decreases with agitation intensity above a “critical” level. The interfacial area increases with increasing agitation and aeration intensities, while the liquid flow rate and coalescing properties of the liquid have no significant effect. The specific interfacial area is correlated in terms of the superficial gas velocity and the maximum power consumption.The correlations obtained for kLa and a were used to calculate kL. It was found that kL depends on the agitation intensity and the bubble size.
A finite element model of the ventilation pattern inside an industrial building: Non‐isothermal case
Authors: Tanguy P. A. , Dupuis M. 
Published: March 2009

AbstractA finite element investigation of the ventilation conditions in a heated building in which the flow is characterized by the existence of a strong effect of natural convection at high Grashof number is presented. The computation of the velocity and the temperature pattern is performed in an intertwined manner, the coupling being performed by a time stepping technique. The proposed solution strategy allows computations at a very reasonable cost. Numerical predictions are compared to experimental data, and exhibit a very good agreement for the velocity field and a fairly good agreement for the temperature.
Heat transfer modelling of sieve trays
Authors: Spagnolo D. A. , Plaice E. L. , Neuburg H. J. , Chuang K. T. 
Published: March 2009

AbstractA heat transfer model that accounts for both gas and liquid phase resistance was developed for sieve trays where the overall heat transfer coefficient is expressed as a function of Sauter‐mean bubble diameter. These diameters, obtained from pilot plant data, were correlated and used to predict point efficiencies on production plant trays. Applying the appropriate liquid flow distribution model allows the prediction of overall tray efficiencies. Predicted temperature profiles have agreed well with measured plant profiles and tray changes at the production plant have resulted in steam savings that were adequately predicted by the model.
Flotation kinetics for titanium, zirconium and bitumen recovery from oilsand tailings
Authors: Ityokumbul M. T. , Bulani W. , Kosaric N. 
Published: March 2009

AbstractThe kinetics of heavy mineral and bitumen recovery from oilsand tailings are presented. The results show that the recovery rates for titanium, zirconium and bitumen were affected by addition of surfactants Tretolite F46 and E3453. Recoveries were a function of time and of the minerals and bitumen present.
Kinetics of reactions involved in pyrolysis of cellulose I. The three reaction model
Authors: Agrawal Ravindra K. 
Published: March 2009

AbstractKinetics of reactions involved in pyrolysis of cellulose has been modeled in terms of a three reaction model. In this model it is assumed that cellulose decomposes to tars, chars and gaseous products via three competitive first‐order reactions. Arrhenius parameters have been obtained to describe the rate constants of these reactions. The three reaction model predicts the weight loss data reasonably well. Product yields of tars, chars and gases predicted by the three reaction model are compared over the temperature range 250 to 360°C. In this communication a technique for analyzing experimental data of a solid state reaction is presented.
Heats of mixing of amine/alkane and amine/alcohol systems at 288.15 and 308.15 K. Correlation and prediction with AGSM and with the quasi‐chemical theory
Authors: Chamblain J. F. , Vera J. H. 
Published: March 2009

AbstractExperimental heats of mixing data for n‐amylamine with n‐heptane and n‐nonane and with 1‐hexanol, 1‐octanol and 1‐decanol at 288.15 and 308.15 K are reported. The data were obtained using a semicontinuous isothermal dilution Van Ness type calorimeter. Experimental data from this work along with the data from other sources were used to test the predictive potential of the Analytical Group Solution Model (AGSM) and of the Quasi‐Chemical theory.
Adsorption of 1‐Butanethiol from kerosene oil on red mud
Authors: Singh A. P. , Singh P. C. , Panday K. K. , Singh V. N. 
Published: March 2009

AbstractAdsorption studies indicate that low concentration and high temperature favour the removal of 1‐butanethiol from kerosene oil by adsorption on red mud. A first order mechanism has been proposed to describe the adsorption in the present system. Equilibrium data at different temperatures fit well in the Langmuir isotherm equation. Thermodynamic parameters for the present system indicate the feasibility of removal of 1‐butanethiol from kerosene oil by adsorption on red mud.
Gamma‐Ray method for measuring liquid expansion coefficient at high temperatures and pressures
Authors: Liu D. D. S. , Patmore D. J. , Yuyitung T. S. , Lipsett J. J. , Chapman K. 
Published: March 2009

AbstractExpandable vessels were designed to measure the density and thermal expansion coefficients of liquid at elevated temperatures and pressures by the gamma‐ray attenuation method. Light Arabian vacuum bottoms was tested from 70°C to 300°C at 13.8 MPa. Results agree well with literature data.
Generalized solutions for a dead‐end duct having a permeable barrier
Authors: Ryan J.T. , Griffin Wayne H. 
Published: March 2009

AbstractThis paper presents an analytical method for calculating the flow and pressure in A dead‐end duct which has a perforated, porous barrier and an auxiliary fan or an obstacle at the end of the duct. The solutions involve two infinite series which can be applied to a general class of differential equations. It is shown that the duct length may be bounded if the barrier is porous only. No such bound exists if there are holes in the barrier. There is a minimum in the flowrate through the duct when there is a fan at the dead end. No such minimum exists when there is an obstacle
The kinetics of the oxidation of propylene over a bismuth molybdate catalyst
Authors: Tan H. S. , Downie J. , Bacon D. W. 
Published: March 2009

AbstractUsing statistical design procedures an initial‐rate study of the oxidation of propylene over a silica‐supported bismuth molybdate catalyst was carried out using a differential‐bed reactor over the following range of conditions: temperatures from 350 to 390°C, oxygen and propylene concentrations from 1.0 to 8.0 mmol/L. Among the models considered a Redox Steady‐State Model (with half‐order oxygen concentration) involving oxygen adsorption and reaction with propylene from the gas phase was found to provide the best fit to the data.
The development of a mini‐plant chlorinator for ferric chloride leach processes
Authors: Tan K. G. , Bedard P. L. 
Published: March 2009

AbstractA packed column reactor was designed and tested for the chlorination of ferrous chloride leach solutions in a co‐current contacting mode. The reaction is exothermic and gas film controlled, and the size of the reactor can be estimated using literature data. The target throughput of 1 L/min solution containing about 1 rnol FeCl2/L, 3 rnol NaCI/L, and 0.5 rnol HCI/L (plus some PbCl2, ZnCl2, and CaSO4) was adequately treated in a 5 cm diameter column packed to a height of 50 cm with 1 cm Raschig rings. Further process development work and kinetic measurements were conducted in smaller (2 cm) diameter columns. These investigations yielded reliable mass transfer data which are useful both for scale up purposes and for a fundamental understanding of the reactions involved.
Viscosity of n‐alcohol binary mixtures
Authors: Orts M. J. , Medina P. , Aucejo A. , Burguet M. C. 
Published: March 2009

AbstractIn this paper liquid mixture viscosities at 25 °C for 18 binary systems formed by primary n‐alcohols have been measured. These values were fitted to Topological Treatment of Mixtures (T.T.M.) The pure compound topological description is obtained following the DARC system rules. A weighting function was introduced to obtain the topological description of a mixture. The results obtained with this model agree with experimental data (average deviation less than 2% in all cases).
An improvement on the quraishi‐fahidy method of dimensional analysis
Authors: Chen J. J. J. 
Published: March 2009

AbstractAn improvement on the Quraishi‐Fahidy method of dimensional analysis is given which is based on the systematic use of basic matrix algebra. This allows the construction of dimensionless groups to be carried out on the computer using standard matrix algebra software, a procedure which would be most effective when the constitutive matrix is very large. While this is not generally the case with many physical systems, the method illustrates the direct application of matrix algebra to an engineering problem.
Flocculation of kaolin suspension with cationic polymer
Authors: Kage Hiroyuki , Matsuno Yoshizo , Higashitani Ko 
Published: March 2009

AbstractFlocculation experiments have been carried out using cationic polymers and kaolin suspensions. The effects of polymer dosage, kaolin concentration, pH, agitation, molecular weight and charge density of polymer, concentration of polymer solution, and addition of inorganic salt were systematically examined. It was found that two optimal points of polymer dosage exist between 0 to 8 × 10−3 kg/kg‐kaolin. The flocs formed at each optimal dosage are different from each other in shape and in size. It is concluded that these two kinds of flocculation are respectively caused by the neutralization of the surface charge of the particles due to the adsorption of free polymer and by the incomplete neutralization owing to the presence of polymer droplets.
Pressure drop through multiorifice gas distributors in fluidized bed columns
Authors: Briens C. L. , Tyagi A. K. , Bergougnou M. A. 
Published: March 2009

AbstractGood grid design is essential for the satisfactory performance of large gas fluidized beds and requires the accurate prediction of the grid pressure drop. Experiments conducted with various perforated plate distributors in a 0.6 m I.D. fluidized bed column showed that the presence of fluidized solids could increase the grid pressure drop by more than 100%. This increase was around 25% for a grid pressure drop to bed pressure drop ratio of 0.4. It was greatly affected by the bed height. An investigation of various possible causes for this increase demonstrated that it is primarily caused by the backflow of fluidized solids into the grid holes under the influence of waves at the bed surface.
Kinetics and selectivity of reactions of 1‐alkenes on HY zeolite: The influence of chain length
Authors: Abbot J. , Wojciechowski B. W. 
Published: March 2009

AbstractCatalytic reactions of 1‐alkenes on HY have been studied at 400°C. Skeletal isomerization to the corresponding rnonornethylalkene is the dominant initial process. Cracking and coke formation are also observed as initial processes. Initial cracking selectivity can be accounted for by monomolecular β‐scission processes involving a carbenium ion intermediate. However, the initial cracking product distribution for l‐hexene must be explained by assuming some contribution from a dimerization‐cracking mechanism.The kinetics of these processes have been fitted by a model previously used to describe the reactions of n‐alkanes. It is found that the rate constants for both skeletal isomerization and cracking increase with chain length of the feed alkene.