I
WILLIAM K. MEERBOTT, ALAN H. CHERRY, JOHN
N. LIMBACH, Jr.],
and BURTON W. ARNOLD
Houston Manufacturing Research Laboratory, Shell Oil Co.,Houston, Tex.
Naphtha Processing over Platforming Catalyst Effect of Sulfur on Catalyst Life Commercially satisfactory catalyst life is attained in producing gasoline from East-West Texas naphtha containing 0.07 weight or less of sulfur
70
THE
increased octane number requirement of automotive engines, to. gether with competition among petroleum refiners for the gasoline market, has produced a steady demand for improved gasoline quality. To meet this need, new refining processes have been developed to increase the octane rating of some refinery streams normally included in gasoline. Catalytic cracking, which has filled a large share of the nation’s needs for motor gasoline for the past 10 years, is being supplemented by many new catalytic reforming processes (9, 70). So great has been the pressure for higher octane ratings in the petroleum industry that catalytic reforming capacity had been increased from 125,000 barrels per day in 1951 to about 1,300,000 by the end of 1956, a rate of growth much greater than for over-all refining capacity during this period or even for catalytic cracking capacity during its peak of expansion. T o meet the expanded demand for catalytic reforming feed stock, it is now frequently necessary to process high-sulfur straight-run naphthas as well as the higher-boiling portion of thermally cracked gasolines. I n reforming over the platinum-containing catalysts normally employed, organic sulfur is readily converted to hydrogen sulfide. Unless provision is made for sulfur removal, a substantial amount of hydrogen sulfide will accumulate in the hydrogen recycle gas system (up to two to three times the concentration of sulfur in the feed), where it is recirculated to the catalyst bed. The problem presented by the presence of sulfur in catalytic reforming feed stocks has received the attention of several investigators recently. Heinemann, Shalit, and Present address, Shell Oil Go., New York, N. Y . 1
650
Briggs (6) have shown that sulfur reduces the dehydrogenation activity of Houdriforming catalyst and have observed a maximum value of sulfur concentration above which little or no dehydrogenation activity is obtained. Hettinger and others (7) have indicated that the dehydrocyclization reaction over Sinclair-Baker platinum catalyst also suffers from the presence of sulfur. Meerbott and associates ( 8 ) have carried out extended pilot plant studies of aromatics production over Platforming catalyst. They, too, noted a loss in dehydrogenation activity with increasing sulfur concentration in the feed. They were able to establish that a n appreciably shorter catalyst life is associated with higher sulfur concentrations, and concluded that there is a threshold value of sulfur concentration, beyond which there is a serious loss in dehydrogenation activity and rapid catalyst activity decline. This critical range of sulfur is in itself a function of the hydrogen partial pressure in the system. I n the face of the evidence of the harmful effect of sulfur in reforming for aromatics production, it was considered necessary to determine to what extent sulfur would be harmful in naphtha Platforming. It was recognized a t the outset of the experimental program, that the limitations imposed by the use of laboratory pilot units in a life-testing study would preclude more than merely outlining the area of threshold sulfur effects, e,‘en for a specific feed stock. The Platforming process is a development of the Universal Oil Products Co., widely employed for aromatics manufacture and naphtha reforming. Various aspects of the application of Platforming to naphtha reforming have been discussed (7-3, 5 ) .
INDUSTRIAL AND ENGINEERING CHEMISTRY
Sulfur may be eliminated from the catalytic reforming system by desulfurization of the feed stock or by removal o l hydrogen sulfide from the recycle stream. I n the latter case, the sulfur concentration over the catalyst i s limited to that in the feed. Four tests were carried out over Platforming catalyst to determinr the effect of sulfur at three concentrations on catalyst life. I n run I, a desulfurized feed (0.01 weight yo sulfur) was employed. I n run I1 the feed contained 0.17 weight sulfur. This run was intended to simulate a commercial operation where the feed contains 0.07 weight yo sulfur and where no recycle gas scrubbing facilities are available or one in which a high-sulfur feed is used with recycle gas scrubbing. Run I11 (0.07 weight yo sulfur in feed) represented an operation in which the feed contains 0.07 weight yo sulfur and recycle gas scrubbing facilities are employed. Run I\’ was a lower pressure life test (450 us. 600 pounds per square inch gage for the other tests) on a desulfurized feed (0.01 weight yo sulfur) where no recycle gas scrubbing was required. To simplify operation and to ensure close control of sulfur levels. recycle gas scrubbing was carried out in all tests. Sulfur concentration in the feed was adjusted, where necessary, by addition of n-butyl mercaptan. Processing schemes were compared on the basis of loss in yield of constant quality [85 research octane number, unleaded, (F-1-0) ] debutanized product. When plotted as a function of time, this comparison provided a direct measure of catalyst activity decline rate. Experimental
The experimental equipment is based on a design supplied by the Universal Oil Products Co. A simplified flow
HYDROGEN IN T H E PETROLEUM INDUSTRY diagram is shown in Figure 1. The apparatus consists of an oil feed system, recycle gas compressor, metering facilities, and a dual external preheaterreactor system. Condensing and recovery vessels, together with a debutanization column, are attached for product stabilization. The recycle gas stream is passed in series over sodium-calcium hydrate (soda-lime) for removal of sulfur and over bauxite for removal of water. I n order to simulate the pressure drop which occurs across the reactor section of a commercial installation, a pressure control valve, located between the two laboratory reactors, provides a pressure differential of 50 pounds per square inch. The control of the reactor temperature is semiadiabatic. An aluminum block furnace, into which the reactor is inserted, is maintained at a constant temperature by means of a Celectray controller. Because of the highly endothermic nature of the dehydrogenation reaction and the type of reactor and furnace construction, however, it is impractical to control temperatures within the catalyst bed. Before entering the second reactor, the product from the first reactor is preheated to essentially the first reactor inlet temperature. During a study of catalyst life, temperature profiles of each catalyst bed are recorded daily. By means of a thermocouple inserted in a n axial thermowell, temperatures are obtained at intervals of 1 inch along each catalyst bed (reprerenting approximately 570 intervals) to establish a n average catalyst bed temperature. These give excellent indications of catalyst activity decline. Temperatures a t selected points in each catalyst bed are recorded hourly, as are other process measurements. The ranges of operating conditions for the life test runs described herein are: Block temperature, O F. Pressure, Ib./sq. inch gage LHSV (volumes of feed per volume of catalyst per hour) Hydrogen-to-feed mole ratio
*
900-950 400-650
tained under a nitrogen blanket while being used as feed stock for Platforming. ‘n-Butyl mercaptan was added to the fractionated feed where necessary to adjust sulfur concentration. The desulfurized naphtha was prepared by processing a sour naphtha over activated bauxite a t 800’ F. and redistilling for immediate use. Inspection properties of the several feed stocks are given in Table I. The feeds for runs I, 11, and IV were from mixed East-West Texas sources. Feed for run I11 was a mixture of West Texas and Mid-Continent naphthas.
determined by a combination of low temperature Podbielniak distillation and a mass spectrometer analysis of the “hexanes plus” fraction for hydrocarbon type. Unleaded research octane ratings (F-1-0) were obtained on the debutanized Platformate as produced. Because fractionation on the debutanization column was effective in splitting between Cq and Cscomponents, octane number was not adjusted for small amounts of either the C ~ Sin the debutanized Platformate or the Cg)s lost in flashing the excess recycle gas.
Analysis The recycle gas and debutanizer averhead gas streams were analyzed by mass spectrometer. The composition of the debutanized Platformate was
Operating Procedure During a catalyst life study 12-hour test periods are made daily for weight balance purposes. An octane rating on the debutanized product from each
EXCESS RECYCLE GAS
” -
RECYCLE GAS
L
SAMPLING
I
I
3 6.0-7.5
Catalyst Universal Oil Products Co. Type R-5 spherical Platforming catalyst was used in all life tests. Fresh catalyst from the same batch was used for each run. The total catalyst charge was divided equally between the two reactors in the system.
Feed Stocks Each feed stock was freshly prepared in one-drum batches from an original sample by redistillation in a continuous column. This procedure served to eliminate potential gum and polymer formation which could result from extended storage. The one-drum lots were re-
Figure 1. unit
Simplified flow diagram of laboratory recycle hydrogen Platforming
VOL. 49, NO. 4
APRIL 1957
651
2
c
CORRECTION ON CORRECTION ON
'/ow %V
test period guides adjustment of unit severity. Product yield data are computed periodically as necessary to control unit operation. ,4s it is impractical invariably to produce a reformate of any specific quality in the pilot laboratory units, adjustments in both yield and temperature are necessary to place experimental results on a consistent basis. Actual yield-octane number data obtained in the course of the run are employed to make any necessary adjustment, correcting yield and octane rating appropriately-in this case to 85 F-1-0 octane number. A typical correction curve is given in Figure 2. Severity of the Platforming operation is normally controlled by furnace temperature in life tests of the type described. O n the basis of furnace temperatures and corresponding octane ratings observed. during the life tests, the adjustment in furnace temperature necessary to
Figure 2, yield correction curve for platforming East-West T~~~~ 2500 to 365O F. S.R. naphtha
FOR CI,C~,AND C3 FOR C~,CS,AND
I
-
3 79
. 80
1 81
I
I
I
/
l
]
1 82 83 84 6 5 66 87 68 ACTUAL F-1-0 OCTANE NUMBER
Table II.
j
89
90
Platforming Operating Conditions and Yields ~ Run I1 _
Run I Catalyst age, bbl./lb. Operating conditions Reactor 1 Av. block temp., F. Av. catalyst temp., O F. Pressure, lb./sq. inch gage Reactor 2 Av. block temp., O F. Av. catalyst temp., F. Pressure, lb./sq. inch gage Av. block temp., F. Av. catalyst temp., F. LHSV H?/oil mole ratio Hydrogen purity, vol. 70 Actual recovery, wt. 70 Yields, charge basis (no loss) H2 CHI
22.2
4.0
10.6
19.6
918 864 650
928 878 650
92 7 878 650
924 876 650
936 896 650
942 920 650
917 907 600 918 886 2.93 6.1 92.8 97.7
927 919 600 928 899 2.98 6.3 91.5 98.8
927 919 600 92 7 898 2.98 6.3 90.9 100.8
925 912 600 925 894 3.13 6.0 92.0 99.0
938 928 600 937 912 2.93 6.7 87.8 98.9
947 936 600 945 928 2.96 7.1 80.6 98.7
%w 1.3 0.4 0.8 2.5 1.6 2.2 3.1 1.3 86.8
%v
...
2.2
I.B.P. 10% 50% 90% E.P. Specific gravity at 60' F. Sulfur, wt. yo Composition, vol. % c3 c 4
C5
CB plus
652
...
14.0
0.9 1.8 3.7
n-C~Hlo Iso-C~HL? n-CsHlz CB plus Aromatics Naphthenes Paraffins Recovery (no loss) Debutanized Platformate Corrected to 85 F-1-0 Product properties F- 1-0 F-1-3 RVP, Ib./sq. inch ASTM distillation, ' F.
_
~
4.4
2.9 3.7 1.6 83.4 40.7 6.7 35.9 100.2 88.7 89.0
... ... ...
100.0
%V
%W
...
1.2
1.3 1.9 3.5 1.7 2.7 3.1 1.7 85.0 39.5 6.5 39.0 100.9 89.8 89.4
0.5 0.9 2.3 1.3 2.1 2.5 1.4 87.8
... ... ...
100.0
85.5
84.4
4.1
4.4
...
... ... ... ... ...
124 212 275 325 378 0.7826
0.7822
2.0 4.3 93.7
2.0 4.0 94.0
... ...
INDUSTRIAL AND ENGINEERING CHEMISTRY
...
...
%w 1.2 0.6 0.9 2.6 1.6 1.9 2.7 1.3 87.2
%v
...
1.5 2.0 3.7 2.2 2.3 3.2 1.6 83.8 38.9 7.6 37.3 100.3 88.6 88.6
... ... ...
100.0
85.0
... ... ... ... ... ... . I .
0.7800
...
0.1 1.5 4.0 94.4
%w
%v
...
1.3 1.8 3.4 2.0 2.7 3.0 1.3 84.8 39.6 8.6 36.6 100.0 89.1 88.6
1.3 0.5 0.8 2.2 1.5 2.0 2.4 1.0 88.3
... ... ...
100.0
%w
%v
...
2.0 2.8 4.6 2.2 3.8 3.6 1.7 81.6 40.0 8.6 33.0 102.3
1.0 0.8 1.3 3.1 1.6 2.9 2.9 1.4 85.0
... ... ...
100.0
86.9 87.2
%v
%w 0.8 1.5 2.0 5.1 2.6 5.1 3.5 4.3 75.1
...
3.9 4.2 7.7 3.7 6.6 5.3 4.3 72.3 34.0 10.9 27.5 108.0 81.9 81.9
... ... ...
100.0
84.3 95.2 2.0
85.5 3.4
...
165 241 280 329 385 0.7909 0.004
165 222 276 326 386 0.7874
... ... ... ... ... ... ...
... 0.2 2.2 97.6
...
...
0.1 0.6 3.1 96.2
85.0
...
... ...
... ...
HYDROGEN IN T H E PETROLEUM INDUSTRY 92
reach a given octane rating is determined. The correction is applied in a manner similar to that by which yields are adjusted. As the Platforming catalyst ages, there is a gradual loss in activity. Initially, the loss in activity is rather rapid, and frequent adjustments in furnace temperature are necessary to maintain Platformate quality. Subsequent changes in catalyst activity are more gradual and require less frequent adjustments. Periodically, therefore, it is necessary to re-establish the yield-octane and yield-furnace temperature relationships upon which the corrections are based. The rate of change of furnace temperature for a given octane quality Platformate can thus be interpreted in terms of rate of catalyst activity decline.
Table Catalyst age, bbl./lb. Operating conditions Reactor 1 Av. block temp., O F. Av. catalyst temp., O F. Pressure, lb./sq. inch gage Reactor 2 Av. block temp., a F. Av. catalyst temp., F. Pressure, lb./sq. inch gage Av. block temp., O F. Av. catalyst temp., O F. LHSV Hdoil mole ratio Hydrogen purity, vol. % Actual recovery, wt. yo Yields, charge basis (no loss) Hz CH4 C2H6 C3Hs Iso-CrHio n-CaHlo Iso-CsHlz n-CbHlZ C6 PIUS Aromatics Naphthenes Paraffins Recovery (no loss) Debutanized Platformate Corrected to 85 F-1-0 Product properties F-1-0 F-1-3 RVP, lb./sq. inch ASTM distillation, O F. I.B.P. 10%
50% 90% E.P. Specific gravity at 60' F. Sulfur, wt. % Composition, vol. % CS c4
cs
c6 plus
It.
m '
I
I
I
I
1
I
24
28
I
RUN I - 650/600 RUN I1 -6501600 RUN l I t - 6 5 0 / 6 0 0 RUN Z - 5 0 0 / 4 5 0
0
TOTAL SULFUR %w Psig 00 1 PSIQ 0 17 Psig 0.07 Pslg 0.01
8
4
12 16 20 CATALYST AGE, Bbl.Feed /Lb.Catolyst
32
Figure 3. Effect of pressure and sulfur concentration on Platforming yield of EastWest Texas naphthas
Platforming Operating Conditions and Yields (Continued) Run I V Run I11
3.2
12.2
22.5
4.4
13.5
21.9
30.0
925 869 650
919 868 650
922 873 650
903 850 500
912 860 500
906 858 500
916 869 450
925 915 600 925 892 2:95 7.4 99.3 99.3
919 911 600 919 890 2.97 6.7 86.7 99.8
922 916 600 922 895 3.00 7.3 89.0 99.8
903 888 450 903 869 3.00 6.6 92.7 98.0
912 897 450 912 878 2.94 6.1 92.4 98.8
906 889 450 906 874 2.92 6.3 92.5 98.9
916 898 400 916 884 3.1 6.7 93.6 99.4
%v
%w 1.1 0.8 1.2 2.6 1.4 1.6 3.2 1.9 86.2
...
2.1 2.7 3.8 1.8 2.1 3.8 2.3 82.4
%v
%w 0.9 0.9 1.5 3.5 2.1 3.3 4.3 2.5 81.0
...
%v
%w
... 1.6
1.1 0.6 1.4 3.9 2.4 3.5 4.0 2.6 80.5
2.2 2.9 3.1 5.3 5.8 2.8 3.3 4.2 4.5 5.2 4.9 3.2 3.1 77.4 77.5 34.6 32.6 9.2 8.5 34.3 35.7 101.0 100.0 103.0 100.0 103.7 85.7 85.6 88.5 86.1 85.5 87.5
... ... ...
...... ...... ...... 82.9
85.3
...
...
..
122 173 259 33 1 391 Oi7775
...
0.1 0.8 6.8 92.3
..
... ...
...
100.0
85.0 95.6 4.4
... ... ...
... ... ... ..
0.7766
0.7736
... ...
...
0.1 1.1
7.6 91.5
*.
..I
...
1.4 7.6 91.0
%v
...
%w 1.5 0.5 0.7 1.3 0.9 1.4 1.6 0.6 91.5
%v
...
%w
1.5 0.6
1.3 1.5 1.9 1.2 1.8 2.0 0.7 87.6 42.9 6.2 38.5 98.0 100.0 90.4 90.3
1.6 1.5 0.7 2.4 1.6 1.4 1.0 1.9 1.5 2.2 1.8 1.0 0.8 86.6 90.5
84.9
85.4
... ...
%v
...
%w
1.3 0.4 0.7 2.0 1.3 2.3 2.6 1.1 88.3
1.1 1.6 3.0 1.7 3.0 3.2 1.3 84.8 38.9 8.4 37.5 98.6 100.0 99.7 100.0
...... ......
... ... ...
... . . . . . .
...
4.5
132 227 274 325 387 0.7892
...
0.5 2.4 2.6 94.5
89.8 90.1
89.3 89.1
...
... ... ... ... ... ... 0.7892 ... 0.5 2.5 3.0 94.0
%v
%w
...
1.0 1.5 3.9 2.3 2.7 2.9 1.8 83.5 39.3 8.0 36.2 99.6 88.2 87.8
1.4 0.4 0.7 2.6 1.7 2.1 2.4 1.5 87.2
... ... ...
100.0
84.6
84.8
... ..
...
4.2
...
138 210 266 324 394 0.7831
0.7792
0.1 3.1 3.8 93.0
0.4 3.4 4.5 91.7
...
VOL. 49, NO. 4
...
... ....
APRIL 1957
653
Effect of Sulfur on Catalyst Activity Decline Typical run data f r m three life tests a t pressures of 650 pounds per square inch gage for the first reactor and 600 for the second reactor (650/600) are presented in Table I1 for runs I, 11, and 111. Curves of yield decline us. catalyst life are shown in Figure 3. A summary of the yield decline rate data for the runs in Figure 3 is given in Table 111. It is evident that desulfurized feed as employed in run I gives the most favorable catalyst activity decline rate: 0.05 volume % debutanized product loss per barrel of feed per pound of catalyst (volume per cent per barrel per pound). Run 111, with 0.07 weight 7 0 sulfur in the feed, gives a tolerable decline rate of 0.10 volume ye per barrel per pound. T h e decline rate for run I1 (0.17 weight % sulfur in the feed) of 0.48 volume % per barrel per pound would normally be undesirable in commercial practice. The catalyst life data of run I1 indicate that under the high-sulfur condition there is a sharp break in the yield curve after a catalyst age of 12 barrels per pound. This curve illustrates the rapid decline in catalyst activity as the life of the catalyst nears exhaustion. The feed stock used in run 111, from West Texas and Mid-Continent sources, was slightly lower in boiling range, aromatics content, and octane number than the feeds for runs I and 11. For this reason, the initial yield of 85 F-1-0 debutanized Platformate shown for run I11 is slightly lower than for the other runs. The decline rate for run I11 is moderate and a good catalyst life is to be expected a t the 0.07 weight yo sulfur
654
level. The initial decline in yield may be due to the higher severity required with this feed to achieve 85 F-1-0 octane level. The evidence obtained in the life tests considered above confirms, for higher boiling range stocks, the observation made earlier by Meerbott and others ( 8 ) when studying the effect of sulfur on Platforming catalyst activity in aromatics manufacture. There is a region of limiting sulfur concentration for naphthas, above which these higher boiling fractions cannot be Platformed successfully without facilities for sulfur removal. The catalyst tolerance limit toward sulfur is undoubtedly influenced by many factors, such as operating severity (octane level desired in the Platformate), total pressure and hydrogen-feed mole ratio. The present study was not intended to include all combinations of variables. The results, however, should indicate the areas in which satisfactory operation may be expected.
Effect'of Sulfur on Yield Sulfur affects the dehydrogenation activity of Platforming catalyst under conditions for aromatics manufacture (8),
and relatively little hydrocracking can be tolerated, lest naphthenes in the feed be destroyed. In naphtha Platforming, however, limited hydrocracking is an important reaction, contributing to octane improvement of the feed and offsetting to some extent the loss in dehydrogenation activity of the catalyst as it ages. The higher hydrogen partial pressures employed in naphtha Platforming contribute to the greater resistance of the catalyst to deactivation from the effects of both sulfur and hydrocracking. While the catalyst is fresh, the sulfur level in the feed has very little effect on the yield of debutanized Platformate produced at a given octane number. This is illustrated in Figure 4, where data have been plotted for the first five barrels of feed per pound of catalyst for three cases in which the feed sulfur concentration was 0.01, 0.12, and 0.17 weight ye. The only difference observed is an increase in debutanized Platformate yield of about 0.5 volume yofor the lowest sulfur level. .4s the catalyst ages, the deactivating effect of sulfur becomes apparent. Reactor temperature profiles taken ar: advancing catalyst ages in run I11 (0.07
Table Ill. Catalyst Activity Decline Rate (Platforming for 85 F-1-0debutanized product) Run N o .
I
I1
I11
IV
0.07 0.01 0.17 Sulfur, wt. feed 0.01 650/600 500/450 650/600 Pressure, lb./sq. inch gage 650/600 0.10 0.10 0.05 0.48 Decline ratea a Vol. % decrease in yield of debutanized product per barrel of feed per pound of catalyst. Data from smooth curves, Figure 3, 0-20 bbl./lb.
INDUSTRIAL AND ENGINEERING CHEMISTRY
H Y D R O G E N IN THE PETROLEUM I N D U S T R Y Table IV. Carbon on Catalyst Platforming for 85 F- 1-0 Debutanized Product [Carbon,wt. % (basis Catalyst) ] Run Reactor Reactor NO.
1
2
I I1 I11
0.30 0.50 0.15 0.72
0.92 2.08 1.19
IV
'
L
weight % sulfur in the feed) evidenced little change in the dehydrogenation activity of the catalyst during the life test. Similar data from run I1 (0.17 weight sulfur), however, indicated that the higher sulfur concentration seriously affected the dehydrogenation activity of the Platforming catalyst under these naphthareforming conditions. The reactor temperature profiles are given in Figures 5 and 6 for runs I1 and 111, respectively. Figure 5 shows that the loss in dehydrogenation activity from the presence of sulfur requires that higher reaction temperatures be used for the production of the 85 F-1-0 product. T h e higher temperature causes a substantial increase in gas production via hydrocracking a t the expense of liquid product yield (Figure 3). Ultimately, the catalyst loses most of its activity and cannot produce the required quality product a t a reasonable yield. Moreover, the decrease in hydrogen purity of the recycle gas and in total hydrogen production which accompanies excessive hydrocracking may seriously affect any auxiliary processing dependent upon hydrogen from catalytic reforming.
Effect of Pressure on Yield T h e advantages of reforming a t the lowest possible pressure have been pointed out by Haensel and Donaldson ( 4 ) . It would, therefore, be expected that, through a moderate reduction in pressure made possible by processing low-sulfur feed, a given product octane rating could be attained with reduced hydrocracking. This premise was tested in run I V a t 500/450 pounds per square inch gage with essentially desulfurized sulfur) for comfeed (0.01 weight parison with the life tests discussed ear-
lier. Data from this run are also included in Table 11. The decline in yield with catalyst age is shown in Figure 3. There is an initial debutanized Platformate yield advantage of about 1.5 volume % on feed basis for the lower pressure operation over the comparable operation a t 650/600 pounds per square inch gage in run I. The operating pressure in run I V was held a t 500/450 pounds per square inch gage u p to 23 barrels of feed per pound of catalyst, then dropped to 450/400 for the remainder of the test. The rate of decline of catalyst activity established in the first 23 barrels per pound of catalyst in run I V is somewhat higher than that of run I. By about 26 barrels of feed per pound of catalyst, the yield advantage of lower pressure operation has disappeared. I n any commercial application, the decision with respect to actual operating pressure for a desulfurized feed will be governed by an economic balance between the advantage in yield obtainable at lower pressure and the advantage in catalyst life obtainable at higher pressure. Considering the runs a t 650/600 pounds per square inch gage of operating pressure, run I (Table IV), in which the lowest catalyst activity decline was found, exhibited the lowest carbon deposit. I n run 11,where the decline became very pronounced beyond 12 barrels of feed per pound of catalyst, the carbon was approximately twice as great as in run I. Carbon on the catalyst from run 111 resembles that from run I. At the low pressure, however, the catalyst showed a much greater tendency for carbon deposition. R u n I V catalyst gave a carbon approximately twice that of run I, although, because of the lower pressure, producing a slightly greater yield of de-
2.26
butanized 85 F-1-0 Platformate. In spite of the greater carbon deposition in run IV, the rate of catalyst activity decline is only slightly greater than that of run I. The carbon deposits in run I V are approximately the same as in run I1 (although the catalyst age is different) but the catalyst activity decline rate is rnarkedly lower. Thus, the activity decline rate is affected not only by the deactivation of the catalyst by carbon deposit but also by the added effect of concentration of the sulfur in the feed.
Acknowledgment The authors wish to acknowledge certain technical information and the basic design of and operational techniques for the experimental apparatus, obtained through private correspondence from the Universal Oil Products Co. to the Shell Oil Co. The authors also wish to express their appreciation to the Shell Oil Co. for permission t6' publish the results of this investigation. Acknowledgment is gratefully accorded to J. W. Ferry, Benjamin Chernoff, and Martha Hills for experimental assistance and calculations, and to the operating and analytical groups for their contribution to this work.
Literature Cited (1) Bland, W. F., Petroleum Processing 5 , No. 4, 351 (1950). (2) Haensel, V., Zbid., 5 , No. 4, 356
.._..
fi050).
(3) Haensel: V., Donaldson, G. R., IND.ENC.CHEM.43,2102 (1951). (4) Haensel, V., Donaldson, G. R., Petroleum Processing 8, No. 2, 236 11956). ( 5 ) Haensel; V., Sterba, M. J., Advances i n Chem. Ser., No. 5 , 60 (1951). ( 6 ) Heinemann, H., Shalit, H., Briggs, W. S., IND. ENG. CHEM.45, 800 (1953). (7) Hettinger, W. P., Jr., Keith, C. D., Gring, J. L., Teter, J. W., Ibid., 47,718 (1 955). (8) Meerbott, W. K., Cherry, A H., Chernoff, B.; Crocoll, J., Heldman, J . D., Kaemmerlen, C. J., Ibid., 46,2026 (1954). (9) Petroleum Processing 10, No. 8 , 1157 (1955). (10) Sittig, M., Warner, W., Petroleum RGner 34,9 (1955). RECEIVED for review September 10, 1956 ACCEPTEDJanuary 2, 1957 VOL. 49, NO. 4
APRIL 1957
655
