Oct., 1962
DOSE
Fig. ].-Effect
2069
XoTES
IN e,v /gKNO,
X
IO-''
of pressure on the decomposition of EX03
Examination of Fig. 1 shows that, contrary to expectations, there is no effect of pressure prior to the break referred to above, nor is there any delay in the appearance of the break. There is, however, an appreciable effect on the yield after the break. Referring to Fig. I, it is apparent that there is a decrease in the yield beyond an absorbed dose of about 45 X lozoe.v./g. The difference in nitrite ion yield without pressure is far greater than any possible experimental error and must be considered as real. This effect of pressure provides further evidence of a particular type of lattice change which occurs in KY03 after about 1 mole yo decomposition, corresponding to an absorbed dose of about 45 X 1 0 2 0 e.v./g. A discussion of the kinetics and mechanism for the decomposition of K N 0 3 as well as other nitrates is now in preparation. ASSOCIATION CONSTANTS OF SILVER(1) AND CHLORIDE IONS I X MOLTEN POTASSIURS NITRATE
each set containing measurements at several concentrations of KC1. At 436' four sets of measurements were made to supplement four sets of measurements4 previously presented to obtain concentrations of ranging from a mole ratio of 1.14 X lo-* to 5.35 X 10-3.5 The limiting slopes at R K C l = 0 of plots of -log ~ A ~ N 8s. O , R g c i a t each fixed concentration of AgZ;03 a t 350 and 436' were evaluated graphically3 and are plotted in Fig. la as a function of R A g s ~ B . The ends of the plotted lines were dashed when it was not fairly certain that the curve went through the last point. The data of ref. 4 a t R A ~ N = O ~3.50 and 5.35 X 10-3 a t 436' are not plotted in Fig. 1. They were not necessary for the evaluation of the association constants and were used as supplementary data only. The limit of this plot of -(a log Y A ~ N O J / dRKCl)f?Kci=o at R A g N o n = 0 is equal to ( K d 2.303). A least squares fit of the data for -log YAgNOa at each fixed concentration of AgX03 to the equation
+
-log YAgNOa = A R K c ~ BR'KCI led to values of A and B which could be used to evaluate K1 and KS. The value of K1 obtained from the extrapolation of A to R A ~ =N 0,~ well within the experimental error, agreed with the value of K1 obtained graphically. The parameter B is a plotted in Fig. lh. The limit of B a t R L y g ~ o = 0, Bo,is equal to (KlK2 - '/&1*)/2.303 and was used to evaluate K2. It should be noted that a relatively large error in B, leads to a relatively small error in K2. An attempt was made to evaluate KI,?,the association constant for the formation of L4g2c1+. Because of scatter in the data, all that could be deduced mas that K 1 2was greater than zero and less than about 40 (iii mole fraction units) at 350 and 436'. The values of Kl and K2 a t 350 and 436' as well as those a t 38503 are given in Table I. A comparison of these constants with the theoretical expressions6 for values of Z = 4, 5 , and 6 led to the values of AE1 and AE, which also are listed in Table I.
By D. L. MANNING, J. BRAUNSTEIN,~~ AYD M. B L A ~ D E H ' ~ Oak E d g e A'atwnal Lahoiatory,z Oak Rzdge, Tennessee
Recezted December $3, 1961
K1KZ
K1 = Z[exp(-AEJRT) =
- 11
(1)
Z(Z - 1) [exp(-(AE1 AEa)/RT) 2 2 exp(--EI/RT) 11 (2)
+
+
I n this note the association constants K1 and K2 for the formation of the species AgCl and AgC12The value of Kr a t 436' (as discussed previously3) in molten K N 0 3 a t 350 and 436' are presented. The association constants were evaluated by a is about 13% higher than the value computed by method previously d e ~ c r i b e d . ~The activity co- Duke and Garfinkel* from our data because Duke efficients of AgN03 in dilute solutions of Ag+ and and Garfinkel neglected to extrapolate to R . k g ~ o l = C1- in molten KN03 were evaluated from e.m.f. ( 5 ) The data have been deposited as Document Number 7127 with the rneasurement~.~At 350' measurements were made AD1 Auxiliary Publications Project, Photoduplication Service. Library a t eight fixed concentrations of AgN03ranging from of Congress, Washington 25, D.C. A copy may be secured by citing Document Number and by remitting $1.25 for photoprints, or to 1.19 X 10-3, with the a mole ratio of 4.95 X $1.25 for 35 nun. microfilm. Advance payment is required. Make (1) (a) On sabbatical leave from the University of Maine, August 1960-August, 1961: (b) k'orth American Axiation Science Center, P.O. Box 309, Cmoga Park, California. (2) Operated f o r the United States Atomic Energy Cominission bv Union Carbide Corporation. ( 3 ) 1LI. Blander, J. Brannstein, and R 121 Lindgren, J A m . Chem. Soc., 84, 1529 (1962). (4) M Blander, I?. F Blankmahip, and R F Newton$ J P h y s . Chem., B S , 1259 (3969).
checks or money orders payable to: Chief, Photoduplication Service, Library of Congress. (6) D. G. Hill, J. BraunstPin, and AI. Blander. J . P h y s Chem., 64, 1038 (1960). (7) hI. Blander J Chem. Phys., 34, 432 (1951). (8) F. R. Duke and H. M. Garfinkel, J . Phys. Chem., 68, 461 (1961). Note that these authors report K I in molality units. Their values of K1 are to be multiplied by Q,SQ t o correspond to the inole fraotion units used i ~ ~ e .
X'OTES
2070
Vol. 66 CATALYTIC ISORIERIZATION OF
2-PENTENE BYJ. C. ROHRER AND J. H. SINFELT Esso Research and Eneineerino Co., Linden, New Jersey Received April 11, 196%
This note presents kinetic data on the skeletal isomerization of 2-pentene over a chlorided alumina catalyst. Included are data on the effect of hydrogen, which are of interest in connection with the observed complex effect of hydrogen on the isomerization of saturated hydrocarbons over a chlorinecontaining platinum on alumina catalyst.lS2 Considerable evidence indicates that the latter reaction involves a step in which olefinic intermediates undergo skeletal rearrangement on acidic alumina ~ites.3~4It was suggested, however, that the effect of hydrogen pressure was not associated with this step.lrz The results of the present study serve to check this point. Experimental Procedure.-The 2-pentene was contacted with the catalyst in the presence of hydrogen or nitrogen, using a flow reactor technique described previously.6 A catalyst charge of 4.0 g. was used throughout. The reaction products were 0 0.4 0.8 1.2 1.6 2 . 0 (x10-31 analyzed by a chromatographic procedure which also has been described previously.a RA~NO, Materials.-The 2-pentene used in this study wm a mixture of 85% cis-2-pentene and 15% trans-2-pentene, and w t t ~ Figure 1. obtained from Matheson Coleman and Bell. A chromatographic analysis showed no other components to be present in detectable amounts (about 0.05%). The alumina catalyst used in this work contained 1.2% chlorine. The catalyst was calcined in air for 4 hr. a t 593", and had a surface area TABLE I of 210 m.a/g. X-Ray diffraction measurements of the alumina prior to calcination showed it to be p-alumina triCALCULATED ASSOCIATION CONSTANTS IX MOLEFRACTION hydrate, a form of alumina which has been described preUNITSAND DERIVED PARAMETERS viously.' T = 350°
T = 385"
T
436'
K I (in mole fraction units)
553 f 20 4 6 0 f 15 3 1 5 i 1 2
- AE1
(kcal./mole) for Z =
1'
4 612
6 21
6 17
5 585 ( 6 562
5 93 5 69
5 86 5 62
Ti2 (in mole fraction
units
215 f 25 169 f 20 117 i 12 6.15
6 18
6 16
581 1 56 5 5 2
5 82 5 53
5 7; 5 45
4 -A&
for Z
(kcal./mole) =
0. The difference makes clear the necessity of a careful analysis of data in order to obtain values of the association constants precise enough for comparison with theory. The calculated values of AE1 and AEz within the estimated error are constant at all three temperatures and for the three values of 2. It is indicated, therefore, that eq. 1 and 2, with co istant values of AEl and AE2, and for any reasonable choice of 2, can be utilized to predict the temperature coefficients of K1 and K 2 which are correct within the experimental precision of the measurements.
Results When 2-pentene is passed over the promoted alumina catalyst, both double bond migration and skeletal isomerization are observed, the former yielding 1-pentene and the latter a mixture of methylbutenes. Interconversion between cis- and trans-Zpentene also is observed. Some hydrogenation to pentanes and cracking to C1-C4 hydrocarbons also are observed, particularly a t the higher temperature (471"). Typical product distribution data are shown in Table I. Interconversion between cis- and trans-Zpentene and the formation of 1-pentene occur more readily than skeletal isomerization to the methylbutenes. Thus, a t the lowest reactant flow rate used ( F / W = 0.18 gram mole 2-pentene charged per hour per gram catalyst), the distribution of cis- and trans-2pentene and 1-pentene is roughly in accord with equilibrium data,8 whereas the ratio of total methyl(1) J. H. Sinfelt and J. C. Rohrer, J . Phya. Chem., 66, 978 (1961). (2) J. C. Rohrer, H. Hurwitz, and J. H. Sinfelt, ibid., 66, 1458
(1961). (3) F. G. Ciapetta, Ind. Eng. Chem., 46, 162 (1953). (4) G. A. Mills, H. Heinemann, T. H. Milliken, and A. C . Oblad, ibzd., 46, 134 (1953). (5) J. H. Sinfelt, H. Hurwitz, and J. C. Rohrer, J . Phys. Chem., 64, 892 (1960). (6) J. C. Robrer and J. H. Sinfelt, ibid., 66, 950 (1962). (7) H. S. Stumpf, A. 8. Russell, J. W. Newsome, and C. M. Tucker. I d . Eng. Chem., 42, 1398 (1950).
