NOTES
Feb., 1958
245
ative heat contents L and excess molal heat TABLE I1 OF METHYLCYCLOPENTANE OVER MECHANI- capacities CpE of acetone-water and acetoneCONVERSION methanol were measured in a Dewar calorimeter DUALFUNCTION CATALYSTS' CALLY-MIXED Catalyst
Product characterization, 30-60 min. Mass-spect. analysis b n20D B MCP Mc- CsHsR Other
some time ago. The results are represented as functions of the mole fraction 2 of acetone by
Pene
Pt-Si02 f SiOI ( 1 : l b y v o l . ) 1.415 2 88 3 0 7 Pt-Si02 SiOzAlzOs, 32 A.1.' ( 1 : l b y v o l . ) 1.453 17 66 12 1 4 Pt-SiOn SiOnAlios, 45 A.I." ( 1 : l b y v o l . ) 1.495 63 14 5 4 14 Reforming catalyst 1.461 41 36 7 8 8 500°, mole ratio Hz:MCP = 5:1, 360 gaseous hourly space velocity; 60-100 mesh catalyst particles, hand-pelleted to 4 mm. pellets. B = benzene, MCP = methylcyclopentane, McPene = methylcyclopentene, CBH~R= alkylbenzenes. c A. I. = activity index (see Table I).
0 THIS INVESTIGATION A SANDONNINI
1000
+
+
*
o
aJ
4
8
'= : 03 V h
?
4
The following experiment demonstrates that the x - 1 0 0 0 over-all activity, in the results just described, did c;l not depend on a transfer of, say, platinum from the Pt-Si02 particles to the Si02-A120a particles during the pelleting operation. Instead of being filled with co-pelleted material as in the above experiments, the reactor was carefully filled with a -2ooc mixture of separate 20-32 mesh granules of 1% \ Pt-Si02 and of Si02-A120a (45 AL), in a volume ratio of 1:1. A methylcyclopentane-hydrogen mixture, identical with that used in the experiments in Table 11,was passed through the tube at a 0.0 0.5 1.0 gaseous hourly space velocity of 300 and a temx, Mole Fraction of Acetone, perature of 480". The refractive index ( n 2 0 ~of) Fig. 1.-Acetone-water system; heat of mixing function at the liquid product collected during the first half 25". hour of the run was 1.476, and for the second half 800 I hour it was 1.472, indicating a, very considerable 0 THIS INVESTIGATION conversion of methylcyclopentane (n2% 1.410) to A HIROBE ~ A control run with the SiO2benzene ( n Z 01.501). A1203 alone under identical conditions showed ~ negligible benzene production ( n 2 01.414). These experiments demonstrate that for the reaction studied, the D.F. and the A.F. need not be present at the same adsorption site, nor even on the same catalyst surface. The intermediate reaction products in this case must be of sufficient stability to diffuse, through the gas phase, from one type of catalytic site to the other. That this is true for at ir least one of the assumed intermediates is shown by the occurrence of considerable amounts of methylcyclopentene in the reaction products (Table 11). Y x While this work demonstrates that the A.F. and D.F. may be separated by a considerable distance J and still achieve good catalytic activity, other features such as stable catalyst life may be affected by the distance between sites.
.. v
1
" I r(
1
1
I
,
l
l
,
1-
I
A
HEAT OF MIXING OF ACETONE WITH WATER AND WITH METHANOL BY A. T. KISTERAND D. C. WALDMAN Shell Development Cornpanu. Emeryvitls, Cdifornio Received Aueust $0, 1967
I n .the courae of investigations of various thermodynamic properties of solutions, the molal rel-
'
1.0
0.5
0.0
x, Mole Fraction of Acetone.
Fig. 2.-Acetone-methanol
systemo; heat of mixing function at 25
.
