October 1951
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
TABLE IX. RECYCLING OF PARTLY AROMATIZED PRODUCT FROM CRACKING NAPHTHENIC NAPHTHA Recycle Charge Material boiling Material boiling below 150° C. below 125O C. Space velocity cc./co./hour Yield of liquid'product, % by wt. on charge
Density a t 20' C. of liquid product Composition of liquid product, % by vol. 75-95' C. (benzene) 95-125O (toluene) 125-150" (xylenes) Above 150° Aromatic content of benzene and toluene fraction, 7 by.vol. Benzene fraction Toluene fraction
0.064 60
0.050 61
0.050 85
0.042
66
After After After After Before Recy- Recy- Before Recy- RecyRecy- elins a t cling a t Recy- cling a t cling a t cling 680 C. 700 C. cling 68OOC. 700° C. 0.826 0 . 8 8 2 0 . 8 8 9 0 . 8 4 7 0.870 0 . 8 8 3 42.5
38:/) .. 68 71
20.6 26.4 8.2
96 98
24.5 26.3
44.7 32.3 11.9
..
98 99
peratures. Whenever possible, charges boiling over the full range from 100"to 200" C. were used. In a few cases-e.g., the sulfur dioxide extract of East Texas naphtha-narrower boiling fractions had to be used. ANALYSISOF CHARGING STOCKS. The charging stocks were distilled in a long column fitted with a Podbielniak spiral. Fractions were taken from 95" to 120' C., 120' to 150' C., and 150" to 180" C., and analyzed separately. The olefins were determined by bromine titration, the combined quantity of olefins and aromatics by treatment with Kattwinkel solution (concentrated sulfuric acid saturated with phosphorus pentoxide) and subsequent distillation (in order to remove any oil-soluble polymers and copolymers). From the aniline points of these distillates their naphthene content was calculated (19). The paraffins were obtained by difference to 100. The data so obtained are in good agreement with those derived from other recent analytical procedures based on physical constants (6, 6, 8, 9,1.4). CRACKING EXPERIMENTS. Table VI summarizes the cracking experiments with the charging stocks, to which Table I refers. The purity of the aromatized liquid can be judged from the example given in Figure 2, referring t o Fischer-Tropsch oil. EXPERIMENTS WITH C.V.R. BENBOLE. Table VI1 gives the characteristics of the charging stock and Table VI11 summarizes the aromatizing cracking experiments. The sulfur content in a representative experiment had fallen from 1.20 to 0.63%, while that of the toluene cut was reduced from 0.63 to 0.38%. It was not possible to desulfurize the charge completely, perhaps because of the presence of thiophene derivatives.
68 70
34.7 23.6 7.1 13.6
31.8 20.0 4.8 12.4
96 98
99.5 99.6
2325
EXPERIMENTS WITH INCOMPLETELY AROMATIZEDXAPHTHENICNAPHTHA. Exneriments were carried out with two fractions-one in which the material boiling below 125' C. was used, and one in which all the material boiling up to 150" C. was taken. The former did not contain the xylene fraction, whereas the latter did. The characteristics of the two materials and the results of some representative experiments are presented in Table IX. ACKNOWLEDGMENT
The Fischer-Tropsch distillate in Table I was supplied by the National Chemical Laboratory (Teddington). The coal tar solvent naphtha- was made available bv the courtesv of Yorkshire Tar Distillers. LITERATURE CITED
Ashmore, S. A., and Penny, E. E., U. S. Patent 2,395,161 (Fob. 19, 1946).
Coulson, E. A., and Handley, R., J. Soc. Chem. Ind., 65, 398 (1946).
Coulson', E. A., Handley, R., Holt, E. C., and Stonestreet, D. A., Ibid., 65, 396 (1946).
Dunstan, A. E., et al., "Science of Petroleum." Vol. 11. D. 1173. London, Oxford University Press, 1938. Gooding, R. M., Adam, N. G., and Rall, H. T., IND. ENO.CHEM., ANAI,. ED., 18, 2 (1946). Grosse, A. V., and Wackher, R. C., Ibdd., 11, 614 (1939). Krause, M. W., Nemzow, M. S., and Ssosakina, J. A., J. G ~ L . Chem. U.S.S.R., 5, 343, 356, 382 (1935); C h m . Zentr., 1936, I, 2722, 2729. Kurtz, S. S., Mills, I. W., Martin, C. C., Harvey, W. T., and Lipkin, M. R., IND.ENQ.CHEM.,ANAL. ED., 19, 175 (1947). Losowoi, A. W., Djakowa, M. K., and Stepanzew, T. G., J. Gen. Chem. U.S.S.R., 7, 1119 (1937); Chem. Zentr., 1938, 11, 1755. National Research Council Committee, "Chemistry of Coal Utilization," p. 1291, 1293, 1396 ff., New York, 1945. Nemzow, M. S., and Poletajew, A. W., J. Gen. Chem. U.S.S.R., 6, 892 (1936); Chem. Zentr. 1936, 11, 2878.
Rosen, Oil Gas J., 39 (Feb. 13, 1941). Saohanen, A. N., "The Chemical Constituents of Petroleum," p. 99, New York, Reinhold Publishing Corp., 1945. Starr, C. E., Jr., Tilton, J. A., and Hockberger, W. G., IND. ENG.CHEM.,39, 195 (1947). Weizmann, C., et al., IND.ENG.CHIM., 43, 2312 (1951). RE~CEIVED August 2, 1949. Contribution from the laboratories of The Weiemann Institute of Science, Rehovoth, Iarael; Petrooarbon Ltd., London Bridge, London E.C. 4, England; and the Grosvenor Laboratory, 25 Grosvenor Crescent Mews, London S.W. 1 , England.
(Aromatizing Cracking of Hydrocarbon Oils)
CONVERSION 'OF BUTYLENE INTO AROMATICS CHAIM WEIZMANN, VICTOR HENRI', AND ERNST BERGMANN The Weismann Institute of Science, Rehovoth, Israel
T
HE observation that in the high temperature formation of aromatic hydrocarbons from mineral oils butadiene plays a central part has led to experiments on the behavior of butylene (I-butylene) under dehydrogenating conditions. Obviously, the formation of the whole range of aromatics is less easy in this case than for mineral oil as their formation requires not only butadiene but other low molecular oleiins ( l a ) which are formed from 1
Deceased,
butylene less easily and not without the danger of concomitant carbonization, The conversion of low molecular olefins into aromatics has been studied before. Dunstan, Hague, and Wheeler (3, see also 1 , 3) observed in experiments in quartz tubes with a space velocity of 80 liters (gas) per hour and liter reactor volume the following yields of an aromatic liquid (no indication being given as to whether the liquid was fully aromatic or not),
INDUSTRIAL AND ENGINEERING CHEMISTRY
2326
Vol. 43, No. 10
EXPERIMENTS ON CONVERSION OF BUTYLEXE INTO AROX~TICS TABLEI. RESULTSOF QUALITATIVE NO.
640
620
700 700 600 600 600 600 l l b
12b 13b a
Olefin
700 600 700 600 600
Packing Copper Copper SiOs Si02 Si02 ThOn Tho2 CeOt CeOn I Rare earth 1 oxides
Furnace material: quartz.
Space Velocity, Liter Liquid Olefin per Liter Reactor Volume per Hour
Tzmz.,
Space Velocity 0.11 0.07 0.13 0.36 0.45 0.30 0.12 0.34
Li uid Proluct, % by Wt. of Charge 12 10
0.12 0.09 0.09
0.06 0.43 b
11 6
3 5 4
2 2 11
10
13
3
Liquid Yield, % by Wt. of Charge
Groll (4), who has experimented in KA2-steel tubes and with slightly higher space velocity, reports the following, lower, yields of liquid product:
Butene
Space Velocity, Liter/Liter/Hour 0.24 0.32
Temp., C. 775 800 800
%
100
100
100
34:5
12:2
75 100 100
$18
7:6
..
.. .. .. 4:s 15.8 ..
100
..
Li uid Yield,
% by%t. of Charge 21.4 40.0 (19.2)a
30.5 (19.2)a
The figures in parentheses indicate the yield in benzene, toluene, and xylene, plus styrene.
As these data are not comparable with those reported in the preceding papers, some qualitative experiments have been carried out using tubes packed either iTith copper metal or certain oxides (the latter in form of pellets) (11). As Table I indicates, under certain conditions fully aromatic liquids can be obtained, containing a xide range of hydrocarbons, but the yields are unattractively low. The temperature does not appreciably affect the result in the range of 600" to 700" C., but the presence of copper, silicon dioxide, cerium dioxide, or the (mixed) oxides of the rare earths has a beneficial effect (of about the same magnitude), a t a space velocity of about 0.1 (liter liquid butylene per liter reaction volume per hour). At higher space velocities, the yield in liquid product is decreasing, and there is also a tendency to the formation of nonaromatic liquid hydrocarbons. The lo^ effickncy of thorium dioxide and zirconium dioxide as catalysts is surprising, in view of the relatively good results achieved with cerium dioxide and the oxides of the rare earths. Cerium dioxide has been used before as catalyst for dehydrogenation reactions (6-9), but the catalytic qualities of the oxides of the rare earths appear not t o have been investigated before. The authors have observed that the rare earth oxides efficiently catalyie the dehydrogenation of ethylbenzene. In this connection, it may be recalled that in the piesence of a catalyst consisting of silicon dioxide, zirconium dioxide, and alumina, butylene is converted at 500" C. into a liquid product with 20.7% yield and that 4473 of that liquid is of aromatic natuie. The aromatics are approximately equally distributed over the three boiling ranges up to l52', 152" to 174", and above 174" C. (10). For the purpose of comparison, a number of parallel experiments have been carried out with propylene. Zirconium dioxide givrs a t 700" C. (and with a space velocity of 0.43) 5% (by Tyeight of the propylene used) of a fully aromatic product, but carbonization sets in very quickly. The product contains 22.6y0 benzene,
..
.. ..
100
100 100 100 100 100
25:s 34.3
..
Furnace material: stainless steel.
200
Olefin Propylene
Aromatics, % by Wt. of Liquid Product BenToluNaph- PhenanXylBene ene enes thalene threne 35.5 24.0 8.0 4.4 3.7
Aromaticity,
C
4:3 14.9
ii:o 3.7 ..
s:ic ..
0.2% anthracene.
1.9% toluene, 1.9% xylene fraction, 12.7% naphthalene, 15.6% phenanthrene, and 1.3y0anthracene. The composition of the aromatized product is, therefore, rather different from the product obtained from butvlene. I n view of the theory discussed in the preceding papers (12, I S ) , it is interesting that the xylene fraction is largely composed of ethylbenzene and styrene-which was to be expected as these two hydrocarbons represent aromatization products of dimerized butadiene (vinylcyclohexene) or of the addition product of butadiene and 1-butene. The styrene has been isolated as the crystalline dibromide; but its presence can easily be deduced from the polymerizability of the xylene fraction. It is especially noteworthy that the rare earth oxides give a fairly good yield of the xylene fraction. The determination of the aromatics \%ascarried out by fractionation and subsequent quantitative spectrographic analysis of the fractions, especially those containing naphthalene, phenanthrene, and anthracene. The low yields in anthracene compared with the quantities of phenanthrene formed are in accordance with the thermochemical data pertaining to the two h) drocarbons as has been pointed out previously ( 1 8 ) . No determination of the higher aromatic hydrocarbons present has becn attempted. ACKNOWLEDGMENT
The rare earth oxides (praseodymium and neodymium) used in the qualitative experiments were supplied by the Socikt6 des Produits Chimiques des Terres Rares, Paris, France. LITERATURE CITED (1) Candea, C., a n d Macovski, E., Bull. sci. &ole polytech. Timisoara, 6, 305-15 (1936). (2) D u n s t a n , il. E., H a g u e , E. N., and Wheeler, R. V., IXD. ENG. CHEM,,26, 307 (1934). (. 3,) D u n s t a n . A. E., a n d Wheeler, R. V. (to Gasoline Products C o . ) , U. S.P a t e n t 1,976,717 (Oct. 16, 1934). (4) Groll. H. P. A.. IND.ENG.CHEM..25. 784 (1933). (5) Haensel, V., a n d Ipatieff, V. N. (to Universal Oil Products C o . ) , U. 5.P a t e n t 2,401,636 (June 4, 1946). (6) S t a n d a r d Oil Development Co., Brit. P a t e n t 565,341 (Nov. 7 , 1944). Suida, H . (to I. G. Farbenind. A - G . ) , U. 8. P a t e n t 1,985,844 (Deo. 25, 1934). Taylor, H . S., a n d coworkers, .J. Am. Chem. Soc., 63, 1385, 2500 f 1941). --, Thomas, C . L. (to Universal Oil Products Co.), U. S. P a t e n t 2,325,287 (July 27, 1944). Voge, H . H., Good, G. &I., a n d Greensfelder, U.S.,IND.EKG. CHEM.,38, 1033 (1946). Weizmann. C., Brit. P a t e n t s 552,115 (March 24, 1943); Ibid., 552.551 (Ami1 14. 1943): U. S. P a t e n t 2,329,672 (Sept. 14, 1944); I b k , 2,384,984 (Sept. 18, 1945). (12) Weizmann, C., e t a l . , IND.ENG.CHEW,43, 2312 (1951). (13) Ibid., p. 2318.
.-,
~
~
\-
RECEIVED August 2, 1949. Contribution from the laboratories of The Weizmann Institute of Science, Rehovoth, Israel; Petrocarbon Ltd. London Bridge, London E.C. 4, England; and the Grosrenor Laboratory, 25 Grosvenor Crescent Mews, London S.W. 1, England.
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