2184
INDUSTRIAL AND ENGINEERING CHEMISTRY
compound 102. Thanks are due t o Iiatharina Bollenbncher for assistance with several of t h e experiments and to numerous other individuals who rendered helpful advice during the course of the work. LITERATURE CITED ( I ) drndt, C. H., Phytopathology, 38,378-87 (1948). ( 2 ) Bechhold, H., and Ehrlich, P., Z. physiol. Chem., 47, 173-99 (1906). (3) Gallacio, d.,U. S. Army Ordnance Lab., Frankford Arsenal, R e p l . R-769 (1947). (4) Goldsworthy, M. C., and Gertler, S. I., Plant Disease Reptr., Supplement, 182,89-109 (1949). (5) Gottlieb, S . , and Marsh, P. B., I N D . ENQ.CHEM., ANAL.ED.. 18, 16-19 (1946). ( 6 ) Gunip, ST. S., U.S. Patent 2,353,724 (Jan. 24, 1941). (7) Ibid., 2,364,012 (Nov. 20, 1943). ( S ) Klarmann, E., Gates, L. W., and Shternov, V. A , , J . A m . Chem. Soc.. 54, 3315-28 (1932).
Vol. 41, No. 10
(9) Uarmann, E., Shternor, V. A . , and Gates, L. W., J . Lab. C’lin. .\fed., 19,835-51 (1933); 20,40-7 (1934). (IO) Kunz, E. C., Luthy, M., and Gump, W. S.,U. 9. Patent 2,368,735 (Feh. 21, 1941). (11) Marsh, P. B . , Teztile Research J . , 17, 597-615 (1947). (12) Marsh, P. B., and Butler, M. L., IND.ENG.CHEM.,38, 701-5 (1946). (13) Marsh, P . B., Greathouse, C . A , Butler, M. L., and Bollenbacher, K., U. S . Dept. Agr., Tech. Bull. 892,1-22 (1945). (14) Prager, B., and Jacobson, P., “Beilstein’s Handhuch der organischen Chemie,” 4th ed., Berlin, Julius Springer, 1918. (15) Richter, F., Ibid., 1st supplement, 1928; 2nd supplement, 1944. (16) Schales, O., and Suthon, A. X i . , Arch. Biochem., 11, 397-404 (1946). (17) Seastone, C. V., Surg. Gynecol. Obstet., 84,355-60 (1947). (18) Suter, C. M., Chem. Reo., 28,268-93 (1941). (19) Ehite, W. L.. and Downing, M. H., dlycologia, 39, 546-55 (1947). R E C E I V E DDecember 13, 1948.
Coprecipitated Chromia-Alumina Catalysts for Naphtha Reforming with Hydrogen E. C. HITGHES, H . \I. STINE, ~ N D S. 31, DARLING The Standard Oil Cornprr.v (Ohio), Cleceland, Ohio Performance of a coprecipitated chroniia-alumina catalyst w a s found to be equivalent to published results obtained with moly bdena-alumina cataly sts. The chromia-alumina catalyst was prepared with careful control of‘ pH during precipitation and of chromia-alumina mole ratio. The catalyst was resistant to high temperatures and to the presence of water vapor and organic sulfur compounds. The use of moderate hydrogen pressures resulted in an appreciable increase in liquid J ielcl. and a rorrwponding clerrease in carbon lay-down. The process was found to be self-sufficient in hy-dropen. Increase in hydrogen pressure had a repressiie effect on the reactions. Obseri ations indicated that the dehy drocy clization proceeded through an olefin intermediary, and that the repressiFe effect of hydrogen was probably due to reiersal of this initial dehydrogenation. The sensitivity of chromia catal>sts toward hydrogen is offered as a possible explanation of differences between chromia and mol?hdma catalj sts w-hich have been reported in the literature.
T
HE oxides of chromium and molybdenum have been r t w g Iiized as excellent catalysts for the dehydrocj-clization of non-
arcni:ttic hytlrocvrbons since the reactions were first d e s c r i i d by X o l d a m k i I and Kamusher ( l a ) aiid by Grosse, Morrcll, 2nd Xhttox (6) yome tn-elve years ago. Since then considerable cffort has been applied t o studies of the catalysts and of the reactions occurring over them. During the same period the use of molyhdenum oxide supported on aluinin:t has been realized i n commercial processes for the catalytic reforming of naphtIi:+ ($, ?, 8. 14). Some of these developments have led to the i m p r r k ) r i t h a t considerable differences exist in the catalytic powers of molybdena and chromia, and t h a t the former is the preferable reforming catalyst. D a t a accumulated during several years’ study of clironiiaalumina catalysts led t o the conclusion t h a t , for the catalytic reforming of naphtha, chromia is fully as good as molybdena. T h e present authors’ results suggest, that the considerable differences between the twvo catalysts reported in the literature are a
result riot so much of fundamental differences iii ct~talytic:tctivity a s of differences in conditions of catalyst preparation an(1 operation, and particularly of difference in response to Iij-drogen pressure. Publication of results of naphtha ”hydroforming” with it molybdena-alumina catalyst ( 7 ) permits coniparisori with the which performance of chroniia-alumina under hydrogen pressursts. SAPHTHA FEEDSTOCKS.The naphthas used in this work were straight-run naphthas from Illinois crude. T h e following properties are representative of the naphtha used in catalyst activity tests and other work: Illiriois 53.1 195 246 290 316 406 42 19 0.04
is
0 LL E
S a p h t h a source and naphtha volatility were not investigated independent variables.
”
KEY 0 CHROMIA,IIO
PARTIAL PRESSURE
Figure 2. Effect of Hydrogen on Yields of Liquid a n d Carbon over Chromia-Alumina at 80 Octane Level
SIELD-OCTAKE RELATIOS
Uec;iuse product quality is of primary importance, the results of this work were related to the octane number of the product gxsoline, and variables were compared at, equivalent octane level Then possible. The yield was commonly nieasured in terms of 400” F. end point gasoline containing :ill the butane produced i n processing. This quantity is rcferred tu in the figures and di5cussion as ‘ d l O O ~ oC, gasoline.” Figure 1 shows the relation between yield and octane for chromia-alumina operation under hydrogen pressures of 100 to 150 pounds per square inch. For comparison data are included from plant and pilot plant, “hydroforming” of mid-continent, naphtha over molybdena-alumina catalyst as cited b y Hill, Vincent,, and Everett (8). T h e midcontinent naphthas were similar in boiling range to the naphtha used in the present work and had somewhat l o n w octane ratings. 35 compared with -12 F-2 (Motor Method). Since boiling range has been observed to have a greater influence than initial octane level on catalytic reforniing, coniparison of results from these n a p h t h q is not unreasonable. Certain ditta of Greensfelder,
I
--
PSI H2
40-
0
I
I
5
IO
,I
15
TIME ON S l R E A M ,
I
I
20
25
HCUR5
Figure 4. Length of Permissible On-Stream Period When Reforming with Hydrogen over Chrornia-Alumina
I N D U S T R I A L A N D E N G I N E E R I N G CHEMISTRY
2186
Vol. 41, No. 10
1040 1
I.
0
950 J 70
I 72
I 74
-+
I
76
7a
F - 2 OCTANE OF 100% C ,
80
02
GASOLINE
F i g u r e 5 . Effect of H ! d r o g e n on Temperature K e q u i r e m e n t of C h r o n i i a - . i l u m i n a
IWSPOSJE
'ro IIYI)KOGR
The use of hydrogm with chromin-:ilumiiia impi,ovt s !!ir. liquiil yield, the gain being d u e alniost eiitircly to :i ct~irespondinpreduction in the :~niountof c:irbon depwited on the catalyst. =\t tlic same time 1,ydrngrn pressure 11s.;:i rrqjrewivc effect nn iiic reformiiiy rcnctioiis and rieccwitatei iiiore severe operating c-icl e r
- _.
I _
____A_
56 9
53 1
19 0 033 0.013
l '
10
I51 210 267 3-16 422
50% o \ c r 90% over
E n d point Octane No.. F-2
19; 246 290 346 4M 42
49
Operating conditions Temperature, ' F. Total pressure, lb./'sq. i n c h gage
HI partial pressure Start End Feed rate, v.v.h. Recycle gas rate, cu. Hours on stream
iocin
082
Dig
_ _ _ A
snn
1000
1000
-IY(
100
?OO
1.50
34?
-iJ
it.
hbl.
1.50 110 ... . , U.tj 1.0 0 01 FIydrogt-n fed once througli 3 . ,5 z.0 .j ~
Yield. weight T Dry gas Butane Gasoline, ex-(?< Heavv ends
13; 133 1.
Catalyst 2-
1 rp-hly prepared Activity Area, s q . m./gram 16Actirit\hr., lt300° F., drj-
20 Chroniia80 Alumina
,, - , dJ,
18 Chroniia 80 Alumina: 2 Antimon!
46 305
,98';
4 ,i
..
..
i3.7 79.6
0.8 i0.7 80.5
70 S
I'
i-'
4
i9.?
S(
r
i9.3 0,5
iY.O 1 5
79 1
Y(J ? i l
c:n*oline insnection . -~ E X - C gasdine ~ Gravity a t 60' F., A;P.I. 4 9 . 7 A.S.T.M. distillation. F. 132 Initial b.p. 165 10% over 50Y0 ever 235 X.R.i 90% over 402 E n d point 62 % a t 257' F. 6.3 Reid r a p o r pressur? x0.n Octane S o . , , F - 2 100% Ca gasoline 10.2 Reid vapor pressure 81.4 Octane S o . , F-2 10 Reid vapor pressure gas011.ne 7.1 Vol. % butane in gasoline 81 ..? Octane h-0..F-2
Xlolybden?. .Alumins
IO
4.6 i5.i
6.1
CATALYST STABILIIT TE~TS
3' 38 38 h e a , 3 ; . m./gram I66 hr.. 1500' F., wet lctivity 3i. 38 35 h a , s q . m./gram ,, I54 Commercially available eatslyst. gel type, obtained from the 11,i t . K r i !egg Company.
l5 7
Yield, voiurne rc Butane C:asoiine, ex-Ch 100c7~Ca gasoline 10 Reid r a p o r pr?ssIjre easoline Excess butane
hot-spot" below 1250' F. Figure 10 gives an evample of such B rest a t an operating temperature of 950' F.. a total pressure n i 100 pounds per square inch gage, and a hydrogen-naphtha ratio of 3 to 1, and a naphtha feed rate of 1 v.v.h. (volume of liquid hydrocarbon feed per volume of catalyst per hour). Although the catalyst lost activity rapidly at first, the drop soon leveled out a t 2 much less rapid rate of decline. This and similar tests were noT cartied to ultimdte eatal. st failure, but the relatively slow IOSP of Activity during the latter pdrt of the tests was interpretprl as 9 t'iirther indication of siiitshlf cstnl7 qt life.
TABLE 11
'y,.
Vol. 41, No 10
19.5
115 166 240
322
8.3
n
i j
tJ
49 2
165 180
249
~
iCI , I.
I5P 234 318 366 63
395 60 4 0
328 390 55 1 0
78.0
79.0
11 0 90.7
81.1
i9 2
lo..?
10.5 81.1
70
80.3
10.0
4 4
i6 h
10 7
in
L.
I?
The Illinois naphthas used in this work had a low sulfur co11. rent. T o cheek the effect of sulfur on the catalyst, a portion of thy naphtha was fortified with butyl mercaptan and thiophene f i t give a mercaptan sulfur content of 0.16 weight % and n ring ~111fur content of 0.05 wight. %. This fortified stock w a 3 t 1 i i . n reiornied at 980" F., a total pressure of 100 pounds per squ:iw inch gage. a 3 to 1 hydrogen-naphtha mole ratio, a feed rate of I v.v.h. ,tnd :iii on-stream time of 2.5 hours. For 30 cycles the mtalysr ,rctivit,y remained constant at a value of 48, an indicatiori that the sulfur was exerting no poisoning influence on t,he catalyst The catalyst should therefore he satisfactory for use with higl, ?ulfur stocks. The catalyst employed in these tests of sulfur reiistaiice was one which through previous use had reached ari activity of 48, and wa9 thus in an "equilibrium" s h t a n-it11 ~ C ~ ~ < J t o nctivitj-, as reprcscnted in Figure 10
CAT.4LYST STABILITY
lice of the coprecipitated chromia-alumna tau Iys! to deterioration from heat, moisture, alternate oxidation a,nd reduction, and organic sulfur compounds in the feed was investigated, and the catalyst u-as found to be, stable to these condition? within reasonable limits. Stability to heat and moisture was investigated by dererrniiiing catalyst activity before and after calcining the catalyst. for 16 hours at 1600' F. in dry air and a t 1500" in 1 atmosphere oi Fater vapor. The results of these tests are shown in Table I1 For chromia-alumina and chromia-alumina-antimony catalysts, together rrith the results of similar tests performed on R rrlmplr nf commercial molybdena-alumina catalyst. The activity of the commercial catalyst was not ch:inged b\the treatment, presumably because it had been stabilized p r e viously by a similar treatment. The activities of the chromia catalysts after treatment compared favorably with those of the molgbdena, and the surface areas of the chromia-alumina catalyst, determined by the method of Brunaucr, Emmett, and Teller ( 2 ) : held up very well. These results are indicative of the satisfactory stability of the chromia catalyst. Stability to actual operating conditions was inve,$tigazed in a small apparatus operating on an automatic cycle comprking 8 hours on stream, nitrogen purge. 8-hour regeneration, and a second purge. The long regeneration period was required bevause the reactor was not manifolded for multiple air inlets, and a ?low stream of diluted air was necessary to control t,he catalyst
L . I T Y K 4 T I K E CITKI1
A.S.T..\I. D d75-46T B r u n a u e r , Einnirl-:
.,rid 'I'dlw, ./. A m . Chem. SoL,.. 6 0 . 9 0 ~
(193R),
' 3 , B u r k . R. E.. wid
fliiarir;
k,
C ' . , ['.
S.P a t e n t 2,290,033 ~,.Iul\1 4
1942). :-i. B u r t o n , A. -1.. C k i i ~ ~ ~ rt:.i l €3.. . ('litu-sen. W. H . , H u e y , (. S e n g e r , J. E , Chcm. Eng. Progxss. 44, 195 (1948). ,,j~Greensfelder, B. 8. irehibald. K. C:., a n d F u l l e r , D. L . , f b i d
. 43,
561 (1947) :6; Grosse, 4.V., Moi~t41.J.. aril1 S l a t t u x , W . J., IND.Esc,. (IHI;.M 32,528 (1910!. t,ij H i g h t o w e r , J. V., K c J j u r r .\'ntiiral Gasoline Mfr., 20, 153 (1941 :S' Hill, L. R., T-incent. G A , . rtiitl E v e r e t t , E. F., AratZ. Petroleum S e w s , 38, R-456 (,194K'. 9 ) Hoog, H., T.erheus, J. :rind Zliiiicvweg, F. J., Trans. Fnradap S O C . , 35,993 (198% !lo; H u g h e s , E. C., C . d . P a e i t t 2 , (11, I l a t t o x , W .J., * I ,.Am. Chem. Soc., 66, 2059 (1944). (12'' 11oldawskiL B L . , a n d Karriusher. H.. Compt. rend. a i d . . Y C Z C.R.S.S., 1, 336 51036 . (13')P i t k e t h l y . R,c 7 . , i S I P I I I P Tf f. . . Trans. Faraday SOC..35. 979 (1939). (14) S a e g e b a r t h , E . 0..f ' e c w h < r n Engr., 17,95 (1946). ( 1 3 Steiner, H . , J . Am. C'hcm. &I:., 67, 2053 (1945). .e?. H . I t i d . , 63, 1387 (1941). (16) T a y l o r . H . S., and T RECEIVE Octohcr C 2U, 1945.
Presenred before t h e Division of Petroieurb Chemistry a t the 114th hIert,in,o of t h e . 4 \ I E R I C A N C H E X I C A L P O C I F T Y . S t Louis, M u .
C T
