Summary of papers published in this month's research quarterly, I&EC Fundamentals NYLON-PLATINUM CATALYSTS WITH UNUSUAL GEOMETRIC AND SELECTIVE CHARACTERISTICS
Unique platinum catalysts have been prepared by interaction of chloroplatinic acid with various nylons. Catalysts prepared from nylons 66, 6, and 610 exhibited similar activity characteristics for hydrogenation of benzene and produced substantial amounts of the intermediate, cyclohexene. Nylon 3-platinum became active at a higher temperature and only cyclohexane was produced. Nomex-nylon-platinum was inactive. T o explain these differences a geometric factor was postulated based on a n arrangement of platinum corresponding to the position of amide groups in the nylon crystal. Because of the apparent interaction of platinum and the amide groups, platinum is used more efficiently than when deposited on inert supports.
reaction boundary condition have been derived. The effects of variable density in the flow and diffusion equations, interfacial velocity, and multicomponent diffusion have been considered. T h e conservation equations were solved by an approximate method which permitted these effects to be evaluated independently. T h e theory has been compared to experimental data obtained for the I?-GeI4diluent system. Theory and experiment were compared by examining the variation of the ratio of the mass transfer coefficients in the concentrated and dilute gas regions as a function of iodine concentration. For iodine mole fractions between zero and unity and helium and argon diluents, the theory was consistently 7 to 1Oyo below the experimental data. For a reactant gas consisting of pure iodine density variations and interfacial velocity increase by 70Ycthe transfer rate over that which would be expectrd for a constant property system.
Douglas P. Harrison and Howard F. Rase, T h e University of Texas, Austin, Tex.
Donald R. Olander, L'ntuersity of Califurnla, Berkeley, Calif.
I N D .ENG.CHEM.FUNDAMENTALS 6, 161-169 (1967)
IND.ENG.CHEY. FUNDAMENTALS 6, 188-194 (1967)
FITTING KINETIC EQUATIONS TO RATE DATA, ASSUMING MORE THAN ONE SET OF ACTIVE CENTERS ON A CATALYST
RECENT STATISTICAL MECHANICAL THEORIES OF THE THERMODYNAMIC PROPERTIES OF MOLTEN SALTS
Published data on the dehydrogenation reaction of sec-butyl alcohol over a brass catalyst are interpreted according to a model which assumes two different sets of active centers on the catalyst. A satisfactory agreement between observed and calculated rates is obtained. Parameters determined according to this model are of reasonable magnitude.
In ter1r.s of ;L :nodrl ionic melt introduced by Kriss ct a / . ;I correspondin? st;iteL: theory for pure salts and ;I conformd solution theory for binary salt misturss are discussed. Several integrds appearicg in the conforin;il so1utio:i theory r.rc e\du:ited for the first time. A n estension to inolteii salts of the scdled particle tht:ory of d Ileiss. Frisch, .ind Lebo\citz is examined. Stillincer ~ n 1I:iver h a w utilized this extension to calculate the compressibilities, thcri:inl exp;Lnsi\ities, and surface te:liions of severdl siinple salts. Extensive comparisons brtu.t.en theories and ex?eriment ;ire given.
Stein Kolboe, Central Institute for Industrial Research, Oslo 3, AVoraay
I N DEKG.CHEM.FUNDAMENTALS 6, 169-174 (1967) EFFECT OF ULTRASOUND ON CHEMICAL REACTION RATE
T h e effect of ultrasound on hydrolysis of methyl acetate using hydrochloric acid as catalyst was studied in a batch reactor under isothermal condition. T h e reaction rate increased with increasing sonic amplitude. Varying frequency had only negligible effect. .4rrhenius plots showed that ultrasonic vibration increased the higher frequency factor of the rate constant and that there was no effect on activation energy. Mechanical agitation and concentration of acid catalyst were also studied. There was no evidence that extra hydrogen ions were produced by ultrasonic vibration.
J . W . Chen and Walter M . Kalback, Southern Illinois Uniuersity, Carbondale, Ill. IND.ENG.CHEM.FUNDAMENTALS 6, 175-178 (1967) SURFACE CHEMICAL KINETICS AND GAS-PHASE DIFFUSION IN THE GERMANIUM-IODINE REACTION
T h e reaction of gaseous iodine and a rotating disk of germanium was studied in the temperature range 280' to 460 C . 4 clear demarcation between reaction-limited and diffusion-limited regions was observed. I n the reaction-limited region, the rate was proportional to the square root of the iodine concentration and exhibited a n activation energy of 31 kcal. per mole. I n the diffusion-limited region, the rate was practically independent of temperature. The slight increase in rate at the highest temperature studied was attributed to the decomposition of GeI4 into GeIz in the boundary layer.
Donald R. Olander, University of California, Berkeley, Calif. IND.ENG.CHEM.FUNDAMENTALS 6, 178-188 (1967) VARIABLE PROPERTY, INTERFACIAL VELOCITY, AND MULTICOMPONENT DIFFUSION EFFECTS IN THE TRANSPORT LIMITED REACTION OF IODINE AND GERMANIUM
T h e momentum, overall continuity, and two diffusion equations governing rotating disk mass transfer in a ternary system with a
I... L). L i d ; and I I . 7'. D a i i j , 1 . , : i : c r : i / ? fij .\f!ntzcrota, .tlitin~apo/r;, .t f 17/71. I s u . Esb. Ciitsi. Fc\D.%sw\r A L s 6, 194-208
196',
THERMODYNAMIC PROPERTIES OF SOLUTIONS OF ALCOHOLS IN INERT SOLVENTS
Hydrogen bonding in alcohol-inert solvent solutions can be taken into account to give equations for the activity coefficients in closed form. T h e excess functions of Gibbs free energy, enthalpy, and entropy can be readily calculated. This theory is used to calculate the isothermal vapor-liquid equilibrium composition curves and the heats of mixing of binary alcohol-aliphatic hydrocarbon solutions, based on a simple experimental point for each system.
I. A . Wiehe and E. B. Bagley, Washington L'niuersity, St. Louis, Mo. IND.ENG.CHEM.FUNDAMENTALS 6,209-217 (1967) MEASUREMENT OF DIFFUSION COEFFICIENTS FOR CONCENTRATED BINARY POLYMER SOLUTIONS
A simple interferometer technique has been used to determine the concentration profiles in an infinite field of polymer-solvent diffusion for various diffusion times. These profiles were combined by the Baltzmann transformation into a master profile which was analyzed by a method of Duda and Vrentas to give the binary diffusion coefficient as a function of polymer concentration. Techniques which improve accuracy are discussed. The systems used were an acrylonitrile-vinyl acetate copolymer in the solvents dimethylacetamide, dimethyl formamide, and dimethyl sulfoxide. Concentrations ranged from pure solvent to 25Vo polymer by weight. The concentration dependence of the diffusion coefficient is small for each solvent.
D . R. Paul, Chemstrand Research Center, Inc., Durham, .V. C. IKD. ENG.CHEM. FUNDAMENTALS 6,217-222 (1967)
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BRIEFS CRITICAL TEMPERATURES OF METHANE-ALIPHATIC HYDROGEN MIXTURES
The interaction model postulated for the establishment of critical temperatures of methane-free aliphatic hydrocarbon systems has been extended to include mixtures containing methane. This approach required the addition of a separate term to the general expression to account for the nonconforming interactions due to the presence of methane. This method has been applied to a number of binary, ternary, and quinary aliphatic hydrocarbon mixtures. The calculated critical temperatures of these mixtures were compared with corresponding experimental values to produce an overall deviation of 1.53y0for 59 mixtures considered.
O k a n Ekiner and George Thodos, .Yorthwestern L'nisersity, Ecanston, Ill. I N D ENG. . CHEM. FUKDAMENTALS 6 , 222-224 (1967)
A MODEL AND EXPERIMENTAL RESULTS FOR DRAINAGE OF SOLUTION BETWEEN FOAM BUBBLES
The model used for studying the laminar flow of solution in or from the continuous liquid phase between stable foam bubbles postulates that most of the flow is in the spaces enclosed by three bubbles (Plateau borders). The literature models did not adequately describe these borders and used empirical constants to represent the experimentally observed foam drainage. The equations and calculated constants developed show good agreement with experimental results. The equations fit new experimental results and literature data for accumulation of liquid below a stationary bed of foam. T h e density and drainage of foam were correlated for countercurrent, vertical flow of foam and liquid and continuous, time steady-state discharge of foam flowing vertically or horizontally through drainage chambers. T h e results may be used to calculate the maximum flow rates and the drainage conditions for foam separation columns. T h e principal variables were average foam bubble diameters (0.3 to 1.5 mm.), average foam densities (0,001 to 0.34 gram per cc.), dimensions of the foam beds or drainage chambers, and superficial foam or liquid velocities (0 to 1.0 and 0 to 0.35 cm. per second, respectively).
Paul A . Haas, Ouk Ridge .Yational Laboratory, Oak Ridge, Tenn., and H . F . Johnson, Unisersity nf Tennessee, Knoxville, Tenn.
thus can be effective in stabilizing the flow in a vertical or inverted film. T h e electromagnetic force must be on the order of the gravitational force normal to the undisturbed surface to be significant.
J . iM. Crowley, M a x Planck Institut fur Stromungsforschung, Gottingen, Germany
IND.EKG.CHEM.FUNDAMENTALS 6 , 243-246 (1967)
AIR VELOCITY PROFILES I N THE PRESENCE OF COCURRENTLY TRANSPORTED PARTICLES
Air velocity profiles have been measured and correlated for a 43-min. diameter glass riser when transporting 300- and 750micron glass spheres. The measurements were made with a calibrated transversely orientated cylindrical Pitot tube and the results compared with solid-phase drag force density profiles derived from measurements of the velocity and density distribution of the 750-micron particles. At low average ratios of particles to air concentration the dispersed phase causes the air velocities relative to the single-phase profiles to increase in the core and decrease at the wall. h t high average conccntration ratios there are a decrease, a tendency toward plug flow in the core, and an increase in the air velocities toward the wall.
I . D . Doig and G. H . Roper, Uniniversity of x'ew South TVales, Kensington, Australia
IKD. Esc. CHEM.FUKDAMEKTALS 6 , 247-236 (1967)
TWO DIMENSIONLESS GROUPS RELEVANT IN ANALYSIS OF STEADY FLOWS OF VISCOELASTIC MATERIALS
Five flow patterns (viscometric flow, pure shear, elongational flow, fourth-order flow, and a superposition of the first two) are analyzed in detail. The behavior of fluids characterized by an essentially exponential rate of stress relaxation in such flows is discussed. The discussion leads to the introduction of two dimensionless groups relevant for steady flows.
Gianni Astarita, C'nicersity of Delaware, ,\-ewark, IND.
Del.
EKG.CHEM. F U N D A a i E N T A L S 6 , 257-262 (1967)
IND.ENG.CHEM.FUNDAMEKTALS 6 , 225-233 (1967) BREAKTHROUGH PRESSURE FOR RANDOM SPHERE PACKINGS BEHAVIOR OF AIR BUBBLES IN DILUTE AQUEOUS SOLUTIONS
The effects of small quantities of some organic compounds on the size of the air bubbles, the interfacial area, and the oxygen mass transfer coefficient were studied. The substances used were members of the homologous series of mono- and dicarboxylic acids and alcohols. Aloxite plate was used as the gas disperser. The results showed a profound effect of these compounds and a dependence of the effect on the length of the carbon chain of each member of the series. A po5sible explanation of this effect and its practical importance are discussed. S. A. Zieminski, M . M . Caron, and R. B. Blackmore, C'niiersity of Maine, Orono, LMatne IND.
END.C H E M .
FUNDAMENTALS
6 , 233-242 (1967)
EFFECT OF ELECTROMAGNETIC FORCE O N THE STABILITY OF LIQUID FILMS
Steady electric and magnetic fields normal to each other and to the undisturbed surface are applied to a film of poorly conducting liquid flowing down an inclined solid plane under the influence of gravity. This combination of fields exerts a force normal to the undisturbed surface of the film which either stabilizes or destabilizes the flow, depending on the relative directions of the two fields. This force is independent of the orientation of the film, and 132
INDUSTRIAL A N D E N G I N E E R I N G CHEMISTRY
T h e pressure required to force mercury into random sphere packings is evaluated from the distribution function representing probable positions of neighbor particles and the penetration pressure of mercury between four spheres in contact.
R. P. Ictkowski, Research Division, Allis-Chalmers, Milwaukee, IND.
ESG. C H E M .
FUiiDAMENTALS
Wis.
6 , 263-265 (1967)
ANALYTICAL ESTIMATES OF THE PERFORMANCE OF CHEMICAL OSCILLATORS
The methods of nonlinear mechanics are used to develop approximate solutions to the equations describing a simple chemical oscila system generating periodic outputs even when the lator-i.e., inputs are maintained constant. The time average value of the oscillator output is different from the steady-state value and in certain cases performance can be improved. This implies that it is sometimes possible to achieve a performance higher than that corresponding to the optimum steady-state design and that it is sometimes advantageous to design positive feedback control systems which will induce oscillating behavior in an otherwise stable process. T h e range of applicability of the solutions also is discussed.
J . '2.1.Douglas and N . 1'. Gaitonde, University of Rochester, Rochester,
s.Y.
IND.END.CHEM.FUNDAMENTALS 6 , 265-276 (1967)
STOCHASTIC MIXING MODELS FOR CHEMICAL REACTORS
Turbulent chemical reactors are modeled by networks of stirred tanks, with the stochastic nature of the mixing introduced by taking the interstage flows to be stationary Markov processes. Some general features of tracer experiments in these quasi-steady flows are discussed, together with their relation to residence time distributions. T h e statistics of tracer experiments are analyzed, and related on the one hand to the estimation of mixing parameters, and on the other hand to the forecast of average yield from the reactor system under first-order kinetics. T h e variability of the reactor performance and the general story of more complicated kinetic mechanisms are deferred for a later report.
able length and must be accounted for in the meter calibration. Theoretical solutions for entrance-region tube flow were used in conjunction with the theory of rounded-entrance flowmeters to obtain a theoretical solution relating flow rate, downstream pressure, pressure drop, and temperature. A good measure of the flow rate was obtained directly from the theory, and excellent results were obtained when an experimentally determined correction factor was used.
Donald A . Willnughby and Paul A . Kittle, Rohm and Hnas Go., Redstone Research Laboratories, Huntsuille, Ala. I N D .ENG.CHEM.FUNDAMENTALS 6, 304-306 (1967)
F. J . Krambeck, R. Shinnar, and S. K a t z , City College of the City Unioersity o j S e w York, 'Vew York, *V. Y . IND.
E N G .CHEM. FUNDAMENTALS 6, 276-288 (1967) COMMUNICATION. WET-BULB THERMOMETRY OF p-XYLENE-WATER-AIR MIXTURES. VALIDITY OF THE METHOD
CONTROL VECTOR ITERATION IN CHEMICAL PLANT OPTIMIZATION ACCESSORY MINIMIZATION PROBLEM OF JACOB1
A relaxation procedure, based upon the accessory minimization problem of Jacobi, is applied to optimize the temperature profile of a tubular reactor and compared with previous results. Beginning with agradient method to find a suitable primary trajectory, second variations are employed near the optimum to obtain a high rate of convergence. Furthermore, the method leads to a quasi-optimal feedback control design for load disturbances.
The wet-bulb temperatures of water and p-xylene are shown to be mutually independent. The experimental values of the psychometric ratio at various )-xylene humidities are presented. S. H. Chow and G. T . Fisher, Vanderbilt University, .VashLille, Tenn.
I N D .ENG.CHEM.FUNDAMENTALS 6, 306-307 (1967)
F. A . Fine and S. G. Bankoff, >Vorthwestern Unioersity, Ecanston, Ill. I N D ENG. . CHEM.FUNDAMENTALS 6,288-293 (1967)
SECOND-VARIATIONAL METHODS FOR OPTIMIZATION OF DISCRETE SYSTEMS
A second-order control \ ector relaxation procedure, given by Merriam for optimization of continuous systems, is extended to discrete systems. . I s an example, the problem of the optimal temperature sequence in a series of stirred tank reactors is treated, and the results are compared with the continuous case.
COMMUNICATION.
A SIMPLE PROOF OF THE MAXIMUM PRINCIPLE
Considering first and second derivatives of a discrete approximation of a continuous process, the maximum principle is proved a limiting process.
Jorgen Louland, .Vorwegian Institute of Technology, Trondheim, A70rway I N D .E N G .CHEM.FUNDAMENTALS 6 , 307-308 (1967)
F. A . F m e and S. G. Bankoff, .Vorthwestern Untoerstty, Eoansfon, Ill. ISD. ENG.CHEW. FUNDAMENTALS 6,293-299 (1967)
OPTIMUM CONTROL OF A CLASS OF DISTRIBUTEDPARAMETER PROCESSES
Optimal control of a class of processes described by partial differential equations is considered. A transfer function involving a term 1 - exp ( -s - k ) can represent dynamics of these as well as more complex processes. T h e optimal control of the distributedparameter process is derived from that of a related lumped-parameter process, under not unreasonable restrictions, thus circumventing the computational complexity suggested by other studies of partial differential equations. Time-optimal controls are derived for some examples, and are found to require a n infinite number of switches between nonextremal values, even after the process output comes to rest at the desired final state.
COMMUNICATION. OPTIMUM ALLOCATION OF ADSORBENT STAGEWISE ADSORPTION OPERATIONS
IN
Calculations on stagewise contacting operations for adsorption systems obeying the Freudlich and Koble-Corrigan isotherms have shown that countercurrent operation is always superior to crossflow operation, and that crossflow operation in which the adsorbent is split into two portions is always superior to the crossflow operation in which the solution is split into two portions. Hence the latter contacting operation need never be employed. The above conclusion may be valid in general and may apply to systems having equilibrium relationships other than the ones considered in this study. R. G. Lerch and D . A . Ratkowsky, Department of Chemical Engineering, T h e Universitj of British Columbia, Vancouver, B.C., Canada IND. ENG.CHEM. FUNDAMENTALS 6 , 308-310 (1967)
L. B. Kojpel, Purdue UniLerstty, Lafayette, Ind. I N D .ENG.CHEM. FUNDAMENTALS 6, 299-303 (1967)
ANALYSIS AND CALIBRATION OF TUBULAR FLOWMETERS
Capillary flowmeters are capable of accurate measurement of gas flow rates when the flow rate is sufficiently low. However, for large flow rates entrance effects exist throughout a tube of reason-
COMMUNICATION. LOW TEMPERATURE THERMODYNAMIC FUNCTIONS FOR n-HALOGENATED HYDROCARBONS
T h e low ternaerature (298.16' to 100' K . ) thermodvnamic functions (GPO,So; (H" - k o o ) / T, ( F o - H o b ) / T are ) calculated for n-halogenated hydrocarbons, n-C,H*,+lX (X = F, Cl, Br, I ) in the ideal gas state at I-atm. pressure. The functions for the three
(Continued on page 734) VOL. 5 9
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BRIEFS lower members ((21-3) of the series were determined by statistical mechanical means, treating the restricted internal rotational contribution by the approximate Lielmczs-Bondi method. T h e values for the higher members of the series were calculated by linear incremental method, using calculated low temperature methylene group contributions. T h e agreement between the computed results and the few available experimental values is satisfactory. Hugh Kennedy and J a n i s Lielmets, T h e Unioersity of British Columbia, Vancoucer, B. C., Canada IND.ENG.CHEM.FUKDAYENTALS 6,310-312 (1967)
a
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COMMUNICATION. DETERMINATION OF ISOTOPE SEPARATION FACTORS AT ELEVATED PRESSURES. RAYLEIGH DISTILLATION AND SINGLE-STAGE EQUILIBRATION
T h e effect of pressure in the determination of isotope relative volatilities, a, by various methods is discussed. For a particular value of 01 and of the fractional liquid volume, 4, remaining in the still, the relative enrichment ($ - x ) / x O obtained by Rayleigh distillation decreases appreciably with a n increase in pressure, because of the effect of vapor phase holdup. The latter can be significant even at 1 atm. and must be taken into account in high precision measurements of separation factors by this method. Rayleigh distillation is inferior to the single-stage method near the critical point and has no more than marginal advantages at lower pressures. D . Basmadjian, L’niversity of Toronto, Toronto, Ont., Canada, and L. A . Poporski, Chemical Projects, L t d . , Rexdale, Ont., Canada ISD. ENG.CHEhf. FUNDAMENTALS 6, 313-315 (1967)
CATALOG
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COMMUNICATION. REACTIONS
TRANSITION BETWEEN REGIMES IN GAS-SOLID
I n discussing diffusional effects in gas-solid reactions, Shen and Smith arrived at some approximate criteria for the limits of the unstable regime. These criteria may b e made precise at the expense of relatively little calculation using a graph related to those for stability estimates published by Regenass. Rutherford Aris, University of Minnesota, Minneapolis, Minn. IND. ENG.CHESI.FUNDAMENTALS 6,315-317 (1967)
CORRESPONDENCE
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, , microfiltration principles and methods for cleaning critical fluids in industrial and aerospace systems in which a / / contaminating particles larger than the micronic pore size of Millipore filters are removed. Write for a copy of Manual ADM-60, “Ultracleaning of Fluids and Systems”. 28 pages. Available free of charge from Millipore Corporation, Bedford, Massachusetts 01730.
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INDUSTRIAL A N D ENGINEERING CHEMISTRY
Comments on a published article on dynamics of a flow-forced heat exchanger and a reply. Frank Stermole, Colorado School of Mines, Golden, (2010. Lowell B. Koppel and Daniel T . K a m m a n , Purdue University, Lafayette, Ind. IND. ENG.CHEM.FUNDAMENTALS 6, 318-320 (1967)
