A new method for measuring isothermal rates of heterogeneously catalyzed gas reactions is described. The method involves a differential reactor incorporated in a recycling system and affords ease of control, occuracy, and many rate measurements in one run.The results for the reaction system investigated show that four reactions are important: the dehydration of ethanol to ethylene, the reaction of ethanol to form diethyl ether, the dehydration of diethyl ether to ethylene, and the reaction of diethyl ether to form ethanol.It is also shown that the rate controlling steps are the monomolecular surface reactions for the two dehydrations and for the formation of ethanol from diethyl ether, and the bimolecular surface reaction for the formation of diethyl ether from ethanol. The values and the temperature dependence of all pertinent rate and adsorption constants are determined and reported, and they are shown conversion.The measurement of the isothermal rates of heterogeneously catalyzed gas reactions is ordinarily accomplished directly in differential reactors or indirectly in integral ones. The former is a powerful method but difficulties are met in analyzing small differences in concentration across the short bed. The use of integral conversion data is limited by the necessity to hypothesize a rate equation before interpretation is possible and by the experimental problem of maintaining isothermal conditions in the reactor.A recycling differential reactor, first proposed by Dohse ( 5 ) , affords ease of temperature control, accuracy of analysis, and direct measurement of rates. A new reactor based on Dohse's original idea but extensively improved and modernized has been developed and used in this research. Reactants and products are continuously circulated through the catalyst, and samples of the reaction mixture are withdrawn frequently for analysis. The extent of reaction per pass through the catalyst bed is very small; consequently maintenance of isothermal conditions is not difficult. Conversion data, and thus rate data, are determined at many points in a run from the sample analyses, so increased accuracy of the rate data is assured. A run may be continued until very high conversions are attained; hence it is possible to meas- Page 42to correlate very well the'data up to 80% ure the rates over an unusually wide range of conversion in one run.A somewhat similar device was used by Smith, et al.( 1 3 ) , with considerable success for ion exchange systems. Perkins and Rase (10) and Polotniuk and Dobrovol 'skii (11 ) have reported the use of reactor systems involving recycling operations. These devices however involve recychg the reactants and products in a steady state measurement of rates at a given conversion and are not similar to the system described here.The dehydration of ethyl alcohoI over alumina catalyst was selected for study because such rates have not been well-defined and because a moderately complicated array of simultaneous and consecutive reactions is involved. Diethyl ether is an intermediate, and...

The oxidation of carbon monoxide with Hopcalite catalyst was studied in an isothermal recycling reactor with special attention poid to the changes of gas phase compositions with time.Conversion-time data exhibit significant departures from first-order behavior often ascribed to this reaction. In early stages the reaction rate declines more rapidly than would a first-order reaction; later the reverse is true. A mechanism, based on careful analyses of the literature and of our observations, is proposed. A kinetic model based on this mechanism is shown to reproduce the data of any run satisfactorily, but there is a considerable variation in values of the constants from run to run.

Observations on the rate of ion exchange in Dowex 50W resins are reported. These measurements were made under conditions where solid diffusion was the governing phenomenon for six pairs of ions sodium-zinc, sodium-silver, silver-aluminum, zinc-copper, zinc-aluminum, and aluminum-cerium (trivalent). The effects of temperature and of resin cross-linkage were studied with the first system. Exchange in both directions was studied for each pair except the last.Interpretation with a Fick's law model was accomplished, and diffusion coefficients were The kinetic behavior of ion exchange resins is of much theoretical and practical interest. The ultimate aim in the design of a ftred-bed ion exchange installation i s the prediction of break-through curves for a particular set of conditions. Formerly, this was accomplished by the observation of breakthrough curves on a laboratory scale and the interpretation of these curves in terms of a suitable mathematical model to yield the fundamental parameters such as fluid-phase transfer coefficients and solidphase dgusivity. This method has always suffered from the fact that the simpmed assumptions, made so that the appropriate equations could be solved, were in varying degrees unrealistic. The advent of high-speed computers has made possible a reversal in this approach. One can now advantageously measure the pertinent parameters first and let the computer combine these with a minimum of assumptions into a predicted breakthrough curve.One of the fundamental parameters is the dsusivity in the solid phase. The accurate measurement of this property becomes highly desirable, and such measurement was the aim of this work. The experimental method involves EXPERIMENTAL Size SeparationSince diameter of the resin particles is a quantity of great importance in governing the rate of exchange, it was necessary to make a fine cut in particle size. This was accomplished with an elutriation technique in which the resin particles were fluidized by a rising water column. The particles selected were those which flowed over the top of a 2.4-cm. I.D. column but did not flow over the top of a 2.6-em. I.D. column in series with the first. Measurements of the wet, swollen resin diameters were made with a calibrated filar micrometer mounted on a microscope at 50X magnification. The standard deviations in the diameter of a 50-bead sample varied from 4.5 to 8.5% with most sets having deviations of less than 6%. Ian Exchange ApparatusThe ion exchange apparatus is shown in Figure 1. The resin beads were held in a basket, H , 9.6-cm. I.D. x 19.2-cm. high, made of monofilament saran cloth. The weave was roughly equivalent to a 200-mesh screen. The basket was supported on a lucite frame, A, by means of the support rods, J. The frame provided strength and rigidity for the necessary auxiliaries. A baffle, D, made up of 5-mm. O.D. glass rods 15.2-cm. long which connected upper and lower ring plates, extended from the frame into the basket. A feed injector, I(, made of 6-mm. I.D. glass tubing could be introduced thr...

After considerable investigation, it is believed that the most rapid, accurate method for the determination of sodium chlorate in cell liquor produced in chlorine manufacture is the reduction of the chlorate with excess ferrous ammonium sulfate in 40% hydrochloric acid by volume. Ammonium molybdate is used as the catalyst. The method is accurate to within about 1 %, of the amount of chlorate present. It permits greater precision than the sodium arsenite-potassium brómate method.The sample of cell liquor for the sodium chlorate estimation may also serve for a total alkalinity determination if standard hydrochloric acid is used in the initial neutralization process.

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