J u n e , 191;
T H E J O C R N A L O F I N D U S T R I A L A N D E N G I N E E R I N G CHEiMISTRY
of ash in the platinum furnace under strictly oxidizing conditions. T h e consistently lower softening points obtained in t h e kiln m a y be attributed t o t h e much slower r a t e of heating, a n d also t h e possibility of some slight reduction b y products of incomplete combustion. Considering t h e difference in test conditions t h e agreement is remarkably close. S U 1111.4 R Y A N D C 0 N C L U S I O S S
T h e effect of various factors on t h e softening temperature of a number of typical coal ashes has been studied in eight different furnaces, having atmospheres of varying degrees of oxidation and reduction. T h e influences of t h e more i m p o r t a n t factors are summarized as follows: I-SIZE ASD S H A P E O F com-Cones t h a t measured l,'~ in. X 11j2 in. gave closer duplication a n d from I O t o jo" lower average softening points t h a n '/4 in. X I in. cones; 3 , ' 1 6 in. b y I in. cones gave practically t h e same results as 1;/4 in. b y I'/~ in. cones. T h e more slender cones were more satisfactory in giving shorter a n d more definite softening intervals; t h e y also gave less trouble from intumescence due t o evolution of gases from the melting ash. In reducing-atmosphere tests. t h e surrounding gases penetrated a thin cone more uniformly t h a n one with a v-ide base. 11-FIKENESS O F ASH-Ash ground t o a n impalpable powder tended t o soften a t a slightly lower tempert u r e t h a n I O O mesh ash. T h e difference averaged 6 " and in no case exceeded 40'. Ash pulverized t o a t least zoo mesh could be molded into more substantial cones t h a n 1 0 0 mesh material. 111-XKCLINATION O F cosEs-LIounting t h e cones with a considerable inclination, 3 j or 4 j " from t h e vertical, led in some cases t o premature deformation points, which were caused b y a further bending over due t o shrinkage of t h e cone in its base, rather t h a n deformation due t o softening and flowing of t h e ash. Vertical or nearly vertical cones were free from this source of error, a n d gave t h e most concordant indications: IV-RATE O F HEATIxG-In general, slower rates of heating gave lower softening points. R a t e s slower t h a n z o per minute are too time-consuming for practical consideration. Rates faster t h a n IO' per minute led t o inaccurate temperature measurements. Varying t h e rate of heating from z t o I O " per minute caused less increase of softening temperature in oxidizing atmospheres t h a n in reducing atmospheres of hydrogen (see Figs. 1 2 a n d 13). A '2 r a t e of heating gave t h e most uniform results; however, heating j " per minute t o initial deformation a n d t h e n reducing t o 2 " per minute gave practically t h e same results a n d saved considerable time. V0 X I D I Z I N G 0 R R E D U C I S G AT 110 SPHERET h e a t rn 0Sphere in which the ash was heated proved b y far t h e most important factor in causing large variations in t h e softening temperature. A s pointed o u t in t h e introductory theoretical discussion, t h e highest softening points were obtained, either in a n atmosphere of air (platinum furnace), or in a strongly reducing a t mosphere of carbon monoxide ( N o r t h r u p furnace) which prevented t h e iron oxide from acting as a flux-
481
ing agent b y reducing i t t o metallic iron before t h e softening of t h e ash began. T h e lowest softening temperatures were obtained in those atmospheres of mixed gases in which reduction of ferric oxide proceeded mainly t o ferrous oxide, t h e most actil-e phase of iron as regards slag formation a t lower temperatures. Such a condition apparently existed in t h e muffle furnace No. 2 , t h e molybdenum furnace So. I , and in many of the carbon resistance furnace determinations. The maximum variation in softening temperatures due t o different atmospheres ranged from 143 t o 4 9 j 0 C . (see Table X X and Figs. 4, 6, 8, IO, 1 2 , 1 3 a n d 14). S T A S D A R D M E T H O D S F O R D E T E R M I S I N G T H I : SOFT1:SISC. TEIJPERATURE OF ASH
Obviously, t h e statement t h a t a n ash has a "fusing '' or softening temperature of I j o o ' means nothing unless t h e exact conditions of making t h e test are defined. The method m u s t , therefore, he carefully standardized in all its details before comparable results m a y be secured by different workers. T h e most important consideration is t h e atmosphere in which t h e test shall be made. From t h e standpoint of securing results t h a t can be duplicated in different laboratories, t h e softening temperature in air, as was determined in t h e platinum furnace, is undoubtcdly t h e most satisfactory s t a n d a r d ; b u t unfortunately, ash forming in a fuel bed is not free from the cffectsof reducing gases. Consequently, clinkering m a y take place under conditions of partial reduction similar t o those which prevailed when t h e low softening points were obtained in t h e molybdenum or gas furnaces. Therefore, t h e lowest softening temperature of a n ash under such conditions as will reduce t h e ferric oxide t o t h e ferrous form should give t h e most promising relation t o clinker formation under furnace conditions. Such a method will be described in a subsequent paper. A C K I\-0W L E D G ME S T S
The authors desire t o express their deep appreciation of t h e assistance a n d of t h e m a n y helpful suggestions received from G. A. Hulett, consulting chemist of t h e Bureau of h'fines, and from A . V. Bleininger, of t h e Pittsburgh station of the Bureau of Standards. T h e observations in t h e h-orthrup-furnace series and t h e platinum-furnace series of Table X X I were made b y Alex. L. Feild. Some of t h e molybdenumfurnace tests were made b y W. 4. Mueller. T h e chemical analyses were made b y H . H. Hill, W. A . Selvig a n d F. D. Osgood, all of this laboratory. A number of t h e coal samples used in this investigation were furnished b y hlr. E . G. Goodmin, Chief Fuel Inspector of t h e Southern R a i l v a y . CHEMICAL LABORATORY, u. s. BUREAU OF hIINES PITTSBURGH, P A .
PHYSICAL CONSTANTS OF GAS OILS AND DERIVED TARS By WALTERF. RITTMAN A N D GUSTAVEGLOFF Received January 4, 1915
of
I n connection with a general s t u d y of t h e behavior hydrocarbons under different temperatures and
1 Published with the permission of the Director of the Bureau of Mines.
T H E J O C R , V d L O F I N D L ' S T R I A L A-VD E N G I N E E R I A T G C H E M I S T R Y
482
1'01. 7 , hr0. 6
TABLE I-PHYSICALCONST.4NTS O F GAS OILS A N D DERIVEDTARS A N D THEIR DISTILLATES All D a t a for 20° C. unless indicated otherwise. C h a r g e f o r distillations 400 cc. Gas OIL NUXBER1 Specific gravity a t 15.5' C . . . . . . 0.872 Surface tension (dynes per cm.) .... 28.60 Viscositv (snerific) . . . . . . . . . . . . . . 2 . 3 SP gr. T,emp. VOl. 15.5 Sr. T. Refr. C. Cc. 7" OC. dynes ind. 150 3 . 5 0 . 9 0 . 7 9 0 22.40 1.416 ?on 6 . 0 1 . 5 0 , 8 0 0 24.30 1 . 4 3 4 225 4 . 5 1 . 1 0.809 25.57 1 . 4 4 1 250 17.0 4 . 2 0.818 26.28 1.454 275 2 1 . 5 5 . 4 0 . 8 3 6 27.60 1 . 4 6 4 300 4 9 . 0 1 2 . 2 0 . 8 4 9 2 8 . 1 2 1.472 Mixed 101.5 25 . 4 0.837 2 7 . 1 6 1.463 distillate] T a r OIL NCMBER1 Specific gravity a t 1 5 ,So C . . . . . . 1 .07 I Surface tension (dynes per cm.) .... 3 3 . 8 3 Viscosity (specific). . , . , . , , . . . , . 4.04 SP. gr Temp. Vol. 15.5 Sr. T. Refr. OC. Cc. 70 OC dynes ind. 150 7.5 1 . 9 0 . 8 7 0 27.49 1.491 200 17.5 4 . 4 0 . 9 0 3 29.44 1.520 225 26.0 6 . 5 0.940 3 0 . 9 5 1.541 250 4 5 . 0 1 1 . 2 0 . 9 7 5 3 2 . 3 9 1.569 275 33.0 8 . 2 0.983 3 2 . 6 1 1 . 5 7 2 300 29.0 7 . 2 0.995 3 2 . 9 5 1.579 Mixed distillate) 158.0 3 9 . 4 0.970 3 1 . 9 5 1.562
GAS OIL SEMBER 2 0.858 28.40
GAS OIL A-UMBER3 0.872 28.54
.....
2.1
cc. 5.0 4,s 8.0
22.5 25.0 32.0 97 . O 2 4 . 2 0 . 8 2 8 2 6 . 9 0 1 . 4 5 8
TAR OIL(^) N U M B E R2
.
Cc. 3.0 3.5 4.5 17.0 49.0 24.0 101.0
I . 090 34.83 11.86 SP. gr. Vol. 15.5 Sr. T. % ' C . dynes 0.8 . . . 0 . 9 0 . 9 4 0 30:26 1 . 1 0 . 9 5 6 32.44 4 . 2 0.984 33.31 12.3 0.993 33.51 6 . 0 1.010 33.79 2 5 . 3 C 983 3 2 . 2 0
GAS OIL ?;UMBER 4 0.890 28.91
cc. 4.5 8.7 9.0 12.0 24.5 39.5 98.2
Sp. gr. 5'01. 15.5 OC. I'.l' 0.759 2 . 2 0.778 2 . 3 0.i99 3 . 0 0.817 6 . 1 0.837 9.9 0.851 2 4 . 6 0.830
6.R
Sr. T. dynes 21.59 23.79 25.22 26.23 27.18 28.06 25.77
Refr. ind. 1.412 1.434 1.448 1.455 1.464 1.4i2 1,462
Cc. 3.0 12.5 19.0 25.5 27.0 38.0 125,O 31.4 0,833 26.60 1.458
TAROIL N T J M B E4R
TAR OIL(^) KCMBER3
Refr. ind. 1:531 1.562 1.576 1.582 1.589 1.578
Cc. 5.0 6.5 12.5 26.0 43.0 25.0 118.0
1.122 36.55 10.9 Sp. gr. Vol. i 5 . 5 Sr. T. R e f r . Yo C. dynes ind. 1.2 . . . 1 . 6 0 . 9 4 2 3 0 : 2 8 1:532 3 . 1 0 , 9 7 7 33.66 1.551 6 . 5 1.012 3 5 . 2 1 1.572 1 0 . 8 1.027 35.69 1.585 6 . 3 1.047 3 6 . 0 8 1 . 5 9 4 2 9 . 5 0 . 9 6 8 34.10 . . .
Cc. 12.5 28.0 27.5 45.5 42.0 23.0 178.5
1.086 37.6 5.60 S p . gr. 1'01. 15.5 Sr. T. W OC. dynes 3 . 1 0.874 27.44 7 . 0 0,916 29.13 6 . 9 0.956 30.69 1 1 . 4 0.986 3 2 . 1 6 10.5 0.998 32.84 5 . 8 1.018 33.25 44.7 0.968 31.66
Refr. ind. 1.499 1.529 1.553 1.5i6 1.587 1.597 1.566
( a ) M u c h difficulty was experienced in distilling t a r oils Nos. 2 a n d 3, due t o t h e presence or water.
pressures it was considered advisable t o make a s t u d y of t h e properties of gas oils a n d derived t a r s as formed in t h e carbureted water-gas process. With this end in view samples were procured of t h e oils used by plants producing carbureted water gas in four cities of widely different geographic locations. I n addition samples of t h e t a r s resulting from TABLE 11-SURFACETENSIONS OF VARIOUSOIL SUBSTANCE FOHXCLA
Water, HzO.. . . . , . , . Water, HzO.. , . . . . . .
B. P. OC. 100 100
PARAFFINS(Q)
38 Pentane, CsHi2. . . . . . Hexanc. CsHlr . . . , . . . 71 H e p t a n e , CiHle. . . . , . 98.4 Isoheotane. CvHls.. , . . . . 9 1 . 5 Octan'e, C S H ~ S. .. ., . . . . . . 1 2 5 , s Nonane. CoHzo. . . . . . , . . . . 149.5 Decane, CIOHW, . . . , , . . . 173.0 Undecane, CnHzr. , . . . . . . 1 9 4 . 5 Dodecane, C D H Z G.. .. . . . . 2 1 4 . 0 Tridecane, CmH28.. . . . . . . 234.0 Tetradecane, Cl4H30. . . . . . 2 5 2 , s Pentadecane, C15H32 . . . . . 270.5 Hexadecane, CieHs.. . . . . . 287.5 UNSATURATED (b) Amylene, CsHio.. . . . . . . . , , . . . . . . Cetene, CieH3z. , , . . . . . . . . . . . , . . . Acenaphthene, Ci2H1o. . , . . , . . . . . . .4ROMATIC(b)
Benzene, CsHs.
,
. ,. . . , . , .,., .
,
.
Toluene, C;Hs. Xylene. CsHlo 1 : I : 1 : Mesitylene, CsHu
2 . ,
. . . . . . .. . .
3 ,........... 4............
..., . . . .... . .
,
h'aphthalene, CioHs Phenol, CaHjOH. . . , . . . . . . . . . . . . a-Cresol C I H T O H . ,, , . , . , , , . , . , , m-Cresol . , . . . . . . . . . , . , . . . . . . . . $-Cresol. . , , . . . . . . . . . , . . , . . . , . . . BIISCELLANEOUS(b) Mercaptan. . . . . . , . . . . . . . . . . . . . . Mercaptan. . , . , . , , . . . . . . . . . . , . . Thiophene . . . . . . . . . . . . . . . . . . . . . Thiophene . . . . . . . . . . . . . . . . . . . . . Molten paraffin,. . . . , . . . , . , . , . . , Wax. , , . . . . , . . . . . . . . . , . , . . . . . .
AND
i 17.21 1 6 . 5 Mendeleieff 115.13 36.8 27.14 15 . O Mendelejeff 1 3 1 . 3 6 128 Dutoit a n d Friederich 1 2 6 . 6 0 178 28.28 29,86 28,83 30.24 29.2 1 29.07 28.52 32.20 28,97 30.22 27.92 18.74 27 .98 22.86 38.55 38.21 37.78 37.80
1 8 . 1 Walden 1 7 . 5 Volkman 1 1 . 4 Renard a n d Guye 2 0 . 0 Morgan 11 . 2 R a m s a y a n d Shields 1 2 . 5 Volkrnan 1 7 . 5 Volkrnan 1 3 . 8 Feustal 15.7 Llutoit a n d Friederich 1 4 . 0 Feustal 7 . 4 D u t o i t a n d Friederich 1 0 8 , 4 Dutoit and Friederich 127.0 D u t o i t a n d Friederich 177.2 Dutoit a n d Friederich 30 Morgan a n d Egloff 1 2 . 5 Renard and Guye 9 . 0 Bolle and Guye 3 2 . 2 Feustal
23.63 21.62 36.20 33.10 30.56 33.40
2 . 0 R a m s a y a n d Shields 1 6 , O R a m s a y and Shields 0 . 0 Shiff 2 0 . 0 Shiff 5 4 . 0 Quincke 6 8 . 0 Quincke
Jour. Phys., 1897, p. 183. ( h ) Chem. Zenlr., 99, 2 . 474. ( d ) J . A m . Chem. S o r . , 33 (1911), 1284. (i) 1870, p, 6 1 5 , ( e ) Pvoc. A m . A c a d . , a7, 56-92. i ( j ) Z e i f . p h r s . Chem., 242, 1. ~f ,) RW , - - .IL ,iip17n) - _~. - , , h- .i . ( 9 ) J o u r . Chem. SOC.,1898, p. 921. (k) A m . Chem. J o u r . , 19, 419.
".
AND
PARAFFINS
TARCOXSTITCENTS
Hexane(a), . . Heptanecb). . Oktaneca) . . , , , , . , , . . , . , . , . , Nonane(b) . . . . . . . . . . . . . . , . . . Decane(a) . . . . . . . , . . . , . . , . , . , Tetradecane(c) . . . . . . . , . , , , , , . Hexadecane(c) . , , , . , , , , , , , . . . Oktodecane(a) . . . . . , . . . , . , , , . OLEFINES Hexylene(a) . , , . . . . Oktylene(a) . . . . , . IJecylene(a). . . . . . . . . . . . . , , . , AROMATICS Benzene(d). , . . , . . . . . . , , , . . . . Toluene(e) . . . . . . . . . . . . . , . , . , . E t h y l benzene(d).. . , . , . . . . . . . o-Xylene(@ , . . . . . . , . . . . , . , . , . m-Xylene, . . . . . .. $-Xylene. . . . . . . . . . . . . . . . . . . . N-Propyl benzene.. . . . . . . . . . . Isopropyl benzene.. . . . . . . . . . Mesitylene, . . . . . . . . . . . . . . . . . Pseudocumene. , . , . , . . . . , , , . , Cymene.. . . . . . , . , . . , . , . Isobutyl benzene.
. .
.
l i t. p-. r n-. t i.i.r -. .e . .
,
EXPERILIEXTAL
The follov\.ing methods of examination were applied
TARCONSTITCENTS TABLE 111-SPECIFIC GRAVITIESA N D REFRACTIVE INDICES OF VARIOUSOIL
Surface tension(b) At Determinations Value O C . made b y 73.01 20 Sentes(c) 72.69 20 Morgan(d) a n d McAfee Isolations made b y 16.0 11 Warren(e) 20,O 11 Schorlemmer(fl 23.5 12 Young a n d Francis(g) 23.4 12 Crossing(h) 24.3 11 Schorlemmer(i) 24 9 14 Warrenid
( a ) Washburne Bull. A m . Insl. M i n i n g E n g . 1914 p 2367. ( b ) These d a t a 'were gathered f r o m L a n d o l t ' a n d kornstein. CastellEvans, Tables Annuelles Internationales de Constantes, and t h e original (c)
t h e cracking of these identical oils were obtained. Samples of oil a n d t a r were i n each case t a k e n from t h e r u n of t h e same d a y . Information from t h e gas companies indicated t h a t t h e t a r s represented a b o u t I j t o 20 per cent of t h e original oils.
.
B. P. OC . 68
92/94 125.5 136,'138 I71
126 (12 mm.) 151 (12 mm.) I 7 4 (12 mm.) ,...
.... .... 80.4 110.3 134.0 142.0 139.0 138.0 158.5 153.0 164.5 170.0 175.0 167.0
SP. gr 0.665 0.709 0.707 0.740 0.728 0.770 0.780 0.779
Refractive index a t "C. Value 1.378 14.8 15.0 1.404 15.1 1.401 15.0 1.421 14.9 1.411 20.0 1.431 20 1,436 27 1.439
0,689 0.726 0.773
15.2 16 17
1.400 1.416 1.439
0.876 0.871 0.875 0.885 0.869 0.866 0.866 0.863 0.865 0.883 0.862 0.872
20 14.7 14.5 14.1 15.7 14.7 15.7 15.1 14.6
1.501 1.499 1.499 1.508 1.500 1.499 1.494 1.495 1,497 1.507 1.511 1.496
...
13.7 17.5
NAPHTHENES
Cyclohexane(f) . . . . . . . . , . . . , . . 80.8 72.0 iMethylpentamethylene(g),. , . . Methylhexamethylene(h) . . . . . . 101 .o Isohexamethylene(i) , . . . . . . . . . 101 .o Dimethylpentamethylene(j). . . 93/96 Hexahydro-m-xylene ( k ) . . , . . . . 117/118 E t h y l cyclohexane(i) . . . . . . . . . . 130 1,3-DimethyIhexamethylene ( m ) 120 1,l-Dimethylhexamethylene ( m ) .... 1,4-Dimethylhexamethylene (n) 118.2 3-Methyl- 1.2,5-hexamethylene 142/44 1,3,5-Trimethyl cyclohexane. . . 124/36 Monanaphthene(0) . . . . . . . . . . . 1/0/172 1,3-Diethylhexamethylene.. , . . .... Isobutylcyclohexane . . . . . . . . . . 157
SOC.
0.779 0.750 0.769 0.756 0.754 0.758 0.799 0.769 0.773 0.769 0.781 0.788 0.773 0.796 0.804
19.5 20.0
20.0 19.0 20.0 17.0 4.0 20.0 18.0 20.0 20.0 4.0 16.0 22.0
21.0
,427 ,411 ,424 ,418 ,413 ,419 ,433 ,423 ,424 ,424
...
,426 ,433 ,439 ,447
Lando!t a n d Jahn,,Z., phys. Chem., 10 (1892). 303. Bartoli a n d Stracciati, A?zn. chtm. phys., 7 (1886), 382. Uhbelohde a n d .4gthe, Dip. Karlsruhe, 1912. Kuops, Lieb. Ann., 248 (1888). 175; Barbier a n d Rowe, Bull. ., 3 (1890), 255; Weegrnan, Z . phys. Chem., 2 (1888). 237. Landolt a n d Jahn, Z . phys. Chem., 10 (1892), 303. Zelinsky, Chem. Z . , 1901, 11, 985. Zelinsky, Ber., 30 (1897), 387. Generosors a n d Zelinsky, Ibid., 30 (1897). 1539. Zelinslcy a n d R u d s k y , I b i d . , 29 (1896), 403. Ibid., 30 (1897), 1540. Wischin, Naphthene, Braunschweig, 1901, p. 58. Ubbelohde a n d Malexa, Karlsruhe, Dissertation, 1912. Zelinsky a n d h a u m o n , Chem. Z., 1899, 341. Zelinsky, Ber., 40 ( l 9 0 7 ) , 3277. Zelinsky a n d Rudewitz, l b d , 28 (1895). 1343.
J u n e , 191.j
T H E J O r R . V A L O F I L V D C S 1 ' R I A L A-VD E S G I J E E R I - T G C H E M I S T R Y
a s indicated, with t h e results given 1 2 3 4
5
METHOD Fractionai distillation Determinations of specific gravity Determinations of viscosity Determinations of surface tension Determinations of refractive index
in
Table
I:
A P P L I E D TO
Original oils a n d t a r s Original samples a n d distillation cuts Original oils a n d t a r s Original samples a n d distillation cuts Distillation cuts
DISTILLATIOSS were m a d e i n j o o cc. glass flasks arranged with moderately efficient fractionating,colunins of aluminum beads.' Cuts were made a t I jo" C . , zooo C. and thereafter a t z j o intervals u p t o 300' C . ; original charges of 400 cc. were used. T h e results obtained sho.iv t h a t t h e t a r s h a v e a larger percentage of constituents boiling below 300' t h a n t h e original oils. \Then high-boiling petroleum hydrocarbons are
483
a r e much higher t h a n those of t h e oils, showing t h a t aromatic hydrocarbons ha\-e been formed. These are of higher density for a given volatility t h a n arc t h e aliphatic hydrocarbons found i n t h e original oils. S L R F A C E TESSIOK measureiiieiits were made b y t h e Morgan' drop-11-eight method. T h e results are given in dynes per centimeter. ,lgain t h c figures for t h e t a r s , a n d distillation c u t s deriired from t h e m , a r e higher t h a n t h e analogous ones for t h e original oils. I n general. surface tension is a property which increases n-ith specific g r a v i t y , though experience h a s indicated t h e ease with which small quantities of cert a i n impurities influence t h e former constant. -10
I
15-
IED
097 1 5 5
f
ij 45
rO L
C
102-.
097-1
092;I I , '
e n E
087-1
382-1
377-1. 200
150
C U R V E S SHOWING
RELATIOVS BETWEEN
P H Y S I C A L C O X S T A N T S OF
subjected t o increased temperatures, decomposition can t a k e place in a t least t w o ways: ( I ) a simple splitt i n g i n t o aliphatic hydrocarbons of smaller molecular weight; ( z ) a combination of splitting a n d subsequent polymerization i n t o ring compounds. T h e results of such decomposition a r e determined b y t h e prevailing conditions of t e m p e r a t u r e , pressure, concentration, c o n t a c t surface a n d time. SPECIFIC G R A V I T Y determinations were made a t 15.5' C. with a Westphal balance having a p l u m m e t of I cc. displacement. T h e figures representing gravities r u n up steadily with increase i n boiling t e m p e r a t u r e of t h e distillation cuts. T h e gravities of t h e t a r s 1
Rittman and Dean,
THISJOURNAL, 7
(1915), 185.
GAS
O I L S AND
250
3w
DERIVED TARS
R E F R A C T I V E INDICES were measured b y means of t h e Pulfrich Refractometer, at a t e m p e r a t u r e approximating z o o C . T h e values found show relations similar to those of specific g r a v i t y a n d surface tension. T h e accompanying sets of curves plotted according t o t h e values obtained for t h e various oils a n d t a r s are typical a n d show t h a t refractive indices v a r y with volatility. T h e d a t a obtained b y t h e various methods, a s given collectively i n T a b l e I, summarize clearly t h e differences i n t h e properties of t h e t w o classes of products. F o r purposes of comparison, t h e surface tensions, specific gravities a n d refractive indices of a n u m b e r of hydrocarbons, b o t h aliphatic a n d aromatic, h a v e 1
J. A m . Chem. S O C33 , (1911), 349 and 643.
T H E J O U R N A L OF I N D U S T R I A L A N D ENGINEERING C H E M I S T R Y
484
been collected from t h e literature a n d are given i n Tables I 1 a n d 111. CONCLUSIoixS
I-The striking differences between t h e constituents of a n aliphatic oil a n d i t s derived t a r are made evident b y t h e characteristic differences between volatilityg r a v i t y , volatility-refractive index, a n d volatilitysurface tension relations. 11-The experiments reported herewith again verify t h e well-known information t h a t aromatic hydrocaribons can be formed from t h e aliphatic hydrocarbons occurring i n petroleum. 111-The various physical constants of typical gas oils a n d derived t a r s have been measured a n d tabulated. T h e experimental work connected with t h e determinations reported i n this paper was carried o u t i n t h e laboratories of t h e D e p a r t m e n t s of Physical Chemistry a n d Industrial Chemistry of Columbia University, New York. CHEMICAL S E C T I O N O F PETROLEUM
U.s. BUREAUO F
DIVISION
M I N E S , PITTSBURGH
Vol. 7 , No. 6
T h e concentration factor above is considered in t h e sense of changes involved i n t h e admixing of other substances with t h e initial material, such a s t h e decomposit i o n of oil i n a n atmosphere of hydrogen, carbon monoxide, etc. THEORETICAL
,According t o chemical kinetics, a reaction tending t o w a r d a s t a t e of equilibrium will require t i m e t o reach such a s t a t e . -4 reversible reaction m a y be represented t h u s : nlAl I Z ~ A ~ ~ - P Z ~nz’A2‘. ’ A ~ ’. .
+
+
Such a n equation represents t w o reverse reactions, each with a separate reaction velocity: T h e difference between these t w o velocities a t a n y moment of time under constant conditions will give a certain change per u n i t of t i m e i n one direction or t h e other t o w a r d equilibrium. This change per . i n c r e m e n t of time,
dx
- ~ -
dt
’
is commonly shpwn a s follows:
THE TIME FACTOR IN MAKING OIL GAS BY M. c. W H I T A K E R AND C. M. ALEXANDER Received April 1, 1915
T h e production of oil gas is d e p e n d e n t u p o n certain chemical laws which relate t o gas reactions i n general a n d which e m b o d y t h e principles of b o t h t h e r m o d y namics a n d chemical kinetics. I n a n .investigation o n t h e effect of t h e variables, t e m p e r a t u r e , pressure, a n d concentration o n t h e t h e r m a l decomposition of petroleum a n d petroleum distillates, Whitaker a n d R i t t m a n ’ h a v e carefully considered t h e theoretical principles of thermodynamics a s applied t o gas reactions. Their experimental results verified their theoretical conclusions a n d showed t h a t t h e principles of thermodynamics a p p l y t o t h e decomposition of petroleum hydrocarbons a s well a s t o more simple reactions. I n t h e a b o v e work, however, conclusions were d r a w n o n t h e assumption t h a t chemical equilibrium was a t t a i n e d under t h e experimental conditions adopted. It t h e n became a question whether or n o t equilibrium was reached. Undoubtedly t h i s question could be answered b y t h e application of t h e principles of chemical kinetics, which introduced t h e t i m e factor. I n t h e present s t u d y of oil gas production, therefore, four variables-time, t e m p e r a t u r e , pressure a n d concentrat i o n-are recognized . Difficulties were foreseen, however, i n t h e accurate a d l u s t m e n t of t h e above variables i n commercial p l a n t s a n d a basis for control was sought which would fall within t h e range of engineering requirements. U n d e r c o n s t a n t t e m p e r a t u r e a n d pressure conditions, t h e t i m e factor, which can be controlled b y variation of t h e r a t e of oil feed, offers t h e most available means for t h e s t u d y of t h e t h e r m a l decomposition of petroleum a n d petroleum distillates on t h e basis of t h e principles of chemical kinetics. Design of a p p a r a t u s is fixed for a n y one construction a n d hence remains a constant factor while t h e variables are controllable within certain‘ operating limits. 1
THISJOURNAL. 6 (1914), 383, 472.
i n which k a n d k‘ are t h e velocity constants of t h e t w o reverse reactions, (A1), (A2),etc., are t h e concentrations of t h e reacting substances, a n d n l , ? t 2 , etc., their respective molecular exponents a s obtained f r o m a properly balanced equation. T h e above velocity constants v a r y with temperature’ a n d a s a result t e m p e r a t u r e has a very m a r k e d effect u p o n t h e reaction velocities of t h e t w o reverse reactions. T h e effect of t e m p e r a t u r e on a n u m b e r of gas reactions h a s been very carefully studied b y Bodenstein2 a n d t h e f u n d a m e n t a l equations applied mathematically t o t h e experimental results. A t equilibrium, t h e velocities of t h e opposing reactions are equal a n d hence t h e change per increment of t i m e ,
d x = u-u‘ at -- -
ax -
dt
’
must become zero.
= k(Al)n1(A2)n2, . . -k’(Al’)n1’(A2’)nz’. . . = o
Hence,
k -
k’
(A~’)“(AP’)~’’.. . (Al)n1(A2)nP. . - K,
= ____
where K is t h e equilibrium c o n s t a n t . T h u s chemical equilibrium deals only with t h e e n d s t a t e of a reaction a n d t i m e is n o t a factor. Where t i m e is n o t considered t h e relations between t h e s t a t e of equilibrium a n d t h e t h e r m a l values of a reaction can be worked o u t b y t h e application of thermodynamics. Such relations have been developed b y X e r n ~ t ,3~l a y e r a n d A l t m a ~ e r ,a~n d others6 a n d expressed i n t e r m s of mathematical formulas from which equilibrium compositions can be calculated: e. g., t h e Nernst approximate formula: 1 Trautz. Z . Eleklrochem., 18 (1912), 513; Z. physik. Chem.. 68 (19091, 295; 74 (1910). 747; Zellinek, 2. anorg. Chem., 49 (1906), 229. 2 Bodenstein, 2 . physik. Chem.. 29 (1899). 147, 295, 315, 429, 665; Bodenstein and Wolgast, Ibid., 61 (1908), 422. a W. Nernst, “Theoretische Chemie.” 4 hlayer and Altmayer, Ber., 40 (1907). 2134. 5 H. von Wartenberg, 2. physik. C h e m . , 61 (1907). 366.
