2224
INDUSTRIAL AND ENGINEERING CHEMISTRY
one case tlie resin is being used to remove a fluoride compound, probably hydrogen or boron fluoride, from the products of a reaction catalyzed by such substances. The amine resin aluminum chloride product might be of interest in itself as a catalyst, particularly in view of the report of Kacker ant1 Pines (8)on the eii'ect of water on aluminum chloride catalyzed reactions. The Duolite anion exchange resins are also effective in the renioval from nonaqueous media of whole salts whose cations arc capable of forniing complexes with amines. For example, copper resinate is effectively removcd from solution in yasolirie arid anhydrous ferric chloride from solution in ethyl ether. Sumerous metal ions n-hich form hydrates rather than ammines in water solution may he removed by ammine formation IT-ith the aniinc resin in the absence of nater. I n ammiiic farmatioil the nirtitl cation is, of course, an acid according to thc gc.ncralizctl roiiccpt of acids.
Vol. 41, No. 10
Finally, it may be meritionetl tliat Duolite .I-2 is also an cfTec,tive atlsrbeiit for tlie removal oi acidic or niuiue r e x t i v c s u l ~ t ~ $hme of this n-arkia r c p J r t d i r i :i stances from the g ~ phas('. previous paper ( 5 ) . LITERATLRE CITED
(1) Ana. SOC. Testiiqj .lI&riaZs, Stnntlnrds, part 111, 11. 954 ( 1 9 1 2 ) . ( 2 ) Bishop, J. H., J . Phi/s. Chem., 50, 0 (1946). (3) I'uo;s and Straus, J . Polijrne~.Sei.. 3, 246 (194s). (1) Kuiiin and Myers, J . rlm. Chem. SOC.,69, 2 S i 4 (1948). (5) Mills, G . F., U. 6. Dept. of Conirnerce. OTS, JTn-;hitigtorl, I). (
R e p t . PB 13608. (6) Llyors, E'. J., IND. Est:. C H E X . . 35, 563 (194a). (7) Schwarte et al., I b i d . , 32, 1462 (1940). (5) Wacker and Pines, J . Am. C'iiem. Soc., 68, 1042 (1946)
SeDaration of Gas-Oil and Wax I Fractions of Petroleum bv Adsorption I J
BEVERIDGE J. _\LAIR, ALBERT J. S\YEET>IAN, . ~ N DFREDERICK D. ROSSINI \-ational Birreuir of Standards, W'ashington 25, D . C .
Results are reported on the separation of the gas-oil and wax fractions of petroleum by adsorption with silica gel. In a single-pass operation, the gas-oil fraction of petroleum can be separated into three portions-namely, a portion which is a mixture of paraffins and cycloparaffins (naphthenes), a portion w-hich is largely mononuclear aromatics, and a portion w-hich is largely polynuclear aromatics. Similarly, the wax fraction (aroma tic-free
but containing some oily constituents) can be separated into two portions-namely, a portion w-hich is largely paraffins and a portion which is largely cycloparaffins (naphthenes). Data are also giFen on the effect, in the separation of the gas-oil, of changes in several of the factors affecting the separation. h simple analogy between fractionation by adsorption and fractionation by distillation is drawn.
A
10, 12, 13, and 14, and from 8 to 20 nil. per hour for columns 7 an(! 20. These pressuies, which depended oii the length of the packed section and on the temperature of the operation, varied from 110 pounds per square inch gage for colmiins 1, 2, 3, and 4 t(J 15 poundc per square inch gag? for column 20.
R E C E S T report ( 2 ) from this laboratory described the results obtained on the separation of the kerosene fraction of petroleum by adsorption. A previous report ( 1 ) gave results on the separation of the gasoline fraction. This paper describes the separation of the gas-oil and wax fractions of petroleum by adsorption. Some data are also given on the effect, in the separation of the gas-oil, of changes in several of the factors affecting the separation including the temperature of operation, diameter of the fractionating section, and the length of the fractionating section. A simple analogy between fractionation by adsorption and fractionation by distillation is drawn. METHOD AiXD APPARATUS
The method and apparatus used in this inwstigatioii were essentially the same as those previously described ( 1 , 2 ) . The importaiit characteristics of the adsorption columns, used in the experiments reported in this inveetigation, are given in Table I. The adsorimit n-as fresh silica gcl, rrith a particle size distribution such that 60% v a s betn-een 200- and 325-mesh. TKOdifferent lots of adsorbent were used, one of which gave a slightly better separation than the other. However, in the investigation of any one variable, only one lot of adsorbent wits used. The desorbing liquid used for the gas-oil and --as fractions of petroleum m r e , respectively, n-hexanol and cyclohexanol. The inert gas pressure applied t o the columns was adjusted to produce a rate of flow of liquid varj-ing from 30 t o 90 ml. per hour for columns 1, 2, 3, 4,
MATERIALS ISVESTIGATED
T h e gas-oil and wax fractions of petroleum studied in tliis work were from the Ponca, Olila., petroleum which has been undpr i n vestigation by the .1.P.I. Research Project 6 at this burexu qiiicc. 1028 (8-10). T h e gas-oil fraction x a s arbitrarily selected to include all the. hydrocarbon material of the original petroleum that ivould 1x5 expected to boil between 230" and 300" C. a t a pressure of 1 atmosphere. Actually, the material was not subjected to tempc,r:itures in escess of 200" C. T h e fractionation of lower boiling material from the gas-oil had been previously completed in connection Kith the Tvork on the kerosene fraction of the same petroleuni ( 4 , 5 ,11-13). The fractionation of all of the gas-oil, including the heavy end, was performed a t a suitable low pressure by the Gulf Research and Development Company, Pittsburgh, Pa. The wax fraction was prepared from one of the original distillate fractions ( S o . 24) of the lubricant portion of petroleum (3, 8-10) by cstmction n i t h liquid sulfur dioxide a t room tempcrature, by cry~tallizationof the resulting raffinate portion x i t h ethylene chloride a t -18' C., and by filtration of the moltcri was
INDUSTRIAL AND ENGINEERING CHEMISTRY
October 1949
T.IBLEI .
~ ~ M X A ROY F THE CHARACTERISTICS O F THE .IDSORPTION COLLMSS USED I S EXPERIMENTS REPORTED IN THISIXVESTIGATION
Column h-0.
4070 3460 2.16 2230 1.550 1.96 720 501 0.54 20 li3 0.54 248 The upper 50-rm. portion of coluriin 7 !\-as 1.9 c n i . i n diam?trr, a n d t h e ut>per 50-cm. portinn o f cnliirnn '20 2 . 2 ciii. in diameter.
1. 2 , 3 , 4 11). 1%,?3,14
1p0
i 90 iYOn 125O
I
/i
.Idcorhent (Silica Gel) in F L I I IPacked ~ Section Void volume Total l-oid per unit Uasa, ~-olume, \.oluiiie, length, g. cu. c m . c u . cni. sq. cin.
Fractionating Section Inside Length, diameter, 3Iaterial of c 111, cm. construction
.o
TABLE 11. SLXJIARTOF
.IdEs1,erinient
sorption Column
I-0 .
S O .
1
20 13 4 4 4
4 1
1 1 1
1 20 13 10
12 1;
i
3 2
42
THE -$DSORPTIOS ESPERIXENTS os IS THISIWESTIGATION
Packed Length Tempera- of Fract u r e of tionatina Operation. Section,
c.
Room Room 52 52 52 52 52 52 52 52 52 52 Room
Room
Room Room Room Room Room 52 80
3590 1610 520 17'3
Stainless steel Pyrex plasz Pyrex glaba Pyrex glass
2.0 1.9 1 1 . (J
C'
Mass of .Idsorhent. G. 179 1610 3300 3590 3590 35190 3590 3390 3590 3590 3390 3590 170
100
100 100
402
25 50 100 100
805
1610 1610 0 0 3500 3300 3,590
100 100
100 100
GAS-OILREPORTED
..
0,559
0.621 0.696 0 696 0.55i 0.278 0.139 0.527 0.258 0.131 0.067 0.084 0.101 0.621 0.621 0.621 0.481 0.481 0.278 0,278 0 278
1890
922 470 240
300 18 250 500 1000 775 250 1000 1000 1000
.? I 0
1 , .5,5
113i
1.38 1.38 1.T3 3.45 6.92
1157 926 463 23 1 875 428 218 111 139
1.83
3.74 7.34 14.4 11.6
,
...
iis
1.55 1 ,5 3 1 .5.5 2.00
8 8 8
463
3:15 3.45 3 43
1(1
255 510 395 463 463
c,
9 10 10
I
I
1
I
20
43
63
I
I
BO
I
I 130
V O L U M E OF FILTRATE IN MILLILITERS
Figure 1.
through a short column of silica gel. This wax fraction was aromatic-free but contained solile of the oily cycloparaffin (and if present, isoparafin) constituents from the o r i g i n a l l u b r i c a n t fraction. T h e Fyax is estinintctl t o have an average of about 25 carbon ntoriis per molecule (6, 7 ) . SEPARATIOS OF GAS-OIL FRACTION 01;PETROLEUM
Ratio of Ratio oi Length of Packed I-olunie of Column Length Charge t o Containing t o Length ResultVolume l l a s s of t h e Given Containing Shown i l l of Charge. Adsorbent, Charge, Given Figlire Cu. C m . Cu. Cni./G. Cm. Charge 1.0. 100 1000 2500 2500 2000 1000 500
2225
Separation of Gas-Oil by Adsorption i n Column 1.25 \Ieters in Length
GEXERAL RESULTS. Table I1 suiiiiiinrizes the significant iiiformation conceriiing the vnriou. espi.rinicnts r e p o r t t d iii this investigat ioti oil tlie sep:xa!ion of tlic gas-oil t'r:iction of petroleum by adsorption. Figure 1 s1ion.s tlie rcsults tioti t ~ fa clinrge of 100 nil. o f ga:-oil, vcitli tlie expcrinieiit l i t h g performed : i t rooin ti~iiipPrnture in coluiiiii 20, wliicli lins it fractioiiatiiig section 1.23 meters in letigth. Tliese results iiic1ic:ite tlixt t,hiu rclatively short column inay be used satisfactorily on material of tlie gw-oil rnnge t o dcteriiiiiic :irom:itics i r i :t mixture with pnr:iffins and cyciopar;ifiitis, in n ninnrier siniiliir to t h a t previously recomiiietitlrd for 11i:it tirial of tlie gwolirie :md l c c ~ o sciie raiigw ( 1 , 21. Such an expt~ritiivtitalso gi estiiiiate of tlie frnctioii of tht, iironintic hytlroc:irboris n- h i c h :I r e p o IJ. ti u c 1 c : i r :ironintics. Figure 2 s h o w the rebulls of thr .>ep:iratiori by atlsoiytion of :I charge of 1 litci, c ~ f gas-oil, with the esperiiiieiit liciiig perforriirti :it rooni tcniprratui'e i n coluniti 13, wliirh has :L fr:tr*tioiintirig section 7.9 iiioters in lcngt 11. It ia appurotit t 1i:it t!,is sultcd iii the scl):ii,:ition of the gas-oil fraction of petrtrIeum into thri3.e povtioriyn:inic,ly, :i portion ivliicli is a iiiisture of p:ir:iffiiis and c y c 1 o p :I r :i f f i ii s ( ii:i p l i theilea), a portioii wliich is largely iiiotionuc1e:tr nromaticn, aiid a portion wliich is l a r g e l y polyiiuc1e:ir aromatics.
INDUSTRIAL AND ENGINEERING CHEMISTRY
2226
c
t N L
6 %W
n
z
w
2 0 ca
t
B Y AOSORPTION
AROMATICS
TI
1551
x
separation in a regular manner, the best separation being obtained with the smallest charge, D,and the poorest separation with the largest charge, A . With regard t o the aromatic portioii, reducing tiie size of ciiargr gives poorer separatioii, rvliicli is attributable to tiie fact t h a t the actual volunie of the several kinds of aromatic hydrocarbons has been reduced to the ; m o u n t a t which the holdup of the column becomes large in comparison with the volume of material of ii given kind. Figure 5 shows the results of four different experiirients 011 the further separation of the aromatic part These experherits were Of the gas-oil by adsorption. perfornied a t a temperature of 52' C. in column 1, which has a fractionatirig section 16 meters iri length. The total hydrocarbon portioii of the filtrate is taken as 10070. The material charged was selrcted from a given quantity of the gas-oil to include all of the iironint ic port ion plus the paraffin-cyc1opar:affirI iiintrrial at the front end of the aromatic portioii (Figure 3). With the quantity of adsorbent being coli$taut, the volumes of the charges iri the four experiments were, respectively, in ml.: for experiment A , 1800; B , 925; C , 470; D, 2-10. The separation of the aronintic portion is eniiariced as the voliinie of the cliarge is successively reduced from 1800 to 470 nil., but in not improved in the caae of the smallest charge of 240 nil. I n experiment A , arid to a lesser extent iri experiment B , the capacity of the fractionating section for this difficultseparation has been csceeded. I n experiment D,the holdup of the fractionating section has tiecome too large in relation t o the volume of charge.
GOS-OIL
I
POLYNUCLEAR
I
4
MIXED T Y P E AROMATICCYCLOPARAFFIN
1501
8ENZ.ES
LL
LA w
a
BICYCLOPARAFFINS
I-
n D O F DESORBENT
I
[I
VOLUME
I
I
I
I
Vol. 41, No. 10
2-I
OF FILTRATE IN MILLILITERS
Figure 2. Separation of Gas-Oil by Adsorption i n Column 7.9 Meters i n Length FRKTONATION OF
Figure 3 coiitairis the results of the separation I J ~ adsorption of a charge of 2.5 liters of ga+oil, Tvitti the experiirient being performed a t a temperature of 52" C. in column 4, which has a fractionating sect,ioii I 6 meters in length. The separation obtained is substantially the same as that shown in Figure 2. In the experiments shown in Figures 2 aiid 3, Rome fractionation has occurred in the paraffiiicycloparaffin portion at 0 to 15% by volume, and near 80% by volume. The intermediate portion is a niixture of paraffins and cycloparaffins which have not been fractionated because of the limited capacity of the column for this more difficult, separation. EFFECTOF CHAXGES IN FACTORS AFFECTISG The effect of changes in the ratio of SEPARATION. tjhe total length of the packed section to the length of the column of adsorbent occupied by the material being fractionated is illustrated in Figures 4,5 , and 6. Figure 4 shows the results of four different esperiinents performed a t a temperature of 52" C. in columns 2,3, and 4, which have fractionating section 16 meters in length, on charges of gas-oil having t h P following volumes, in liters: A , 2.5; B , 2.0; C, 1.0; D, 0.5. The total hydrocarbon portion of tile filtrate is taken as loo'%. The break betxvceii the paraffin-cycloparaffiu portion and the aromatic portion occurs, witliiii the reproducibilii y of the experiments, at about the same point for all esperirnents. With regard to the paraffin-cycloparaffin portion, decreasing the size of charge affects the
i
GAS.ML BY ADSOEPTKN
/
i 1
i MIXED TYPE AROMATICCYCLOPAFIAFFH
.-
ALKYL
nD Of OESORBENT L,
0
250
500
1250
I
I
I
I
1500
1750
2000
2250
- .. . I
2500
VOLUME OF FILTRATE IN ML
Figure 3. Separation of Gas-Oil by .4dsorption in Column
16 3Ieters i n Length
INDUSTRIAL AND ENGINEERING CHEMISTRY
October 1949 1
I
I
I
I
-
I
1
_-
-
tionsting aectioii 1.26 meters in length. T h e charge contained about 6 nil. of hydrocarbon material. hlaterial of refractive indcx 1.59 was obtailled f r o m e x p e r i m e n t 7 wvherezs in esperinient 4 0 the Iiiglic,st refructive index was 1.585. T h e effect of changing the length of the fractionating section, with the ratio of the total length of packed section to the length of column occupied by the niitterial being fractionated being kept constant, is illustrated in Figure 8. I n this figure are given the results of three different experiments on the separation of gas-oil, performed a t room temperature in columns 10, 12, and 13, which have fractionating s e c t i o n s with a total length of 7.9 meters and a diameter of 1.9 cm. T h e total hydrocarbon portion of the filtrate is taken as 100%. T h e three experiments had the following vol-
~
I n z\
rbd’
--
CHANGE IN
SIZE OF CHARGE
I
r-
0
‘ c ‘D nD OF XSXQtlNT-,
I 20
I
I
I
I
I
40
I
I
!&-
L
I
85
60
1c
PERCENTAGE BY VOLUME
7
Figure 4. Separation of Gas-Oil by Adsorption in Columns I 6 llleters in Length
I
I
I
I
AROMATIC PORTION OF GAS-ML
I
2227
I
I
I
Figure 5. Separation of the Aromatic Portion of the Gas-Oil by Adsorption in Columns 16 hleters in Length I
c
I
160-
Figure 6 shows the results of the separatioii by adaorption of a charge of 300 mi. of the interniediate parafincycloparaffin portion shown in Figure 3 :It S, with the esperinient being performed at a temperature of 52’ C. in column 1, which has a fractionating seciion 16 meters in length. JTith t h e greater ratio of total length of packed section t o tlie length occupied by t h e material being fractionated, a si1iglc-p11.ssoperation resulted iii tLc separation of the paraffi,i-cyclopnraffin mixture into a 1 ~ w t i o nconsisting largcly of paraffins and a portion i n which the cyc1opar:iffins pred~)niinate. I n Figure 7 t l i v wsults of the separation by :~d>oq)tinii of the tail po~!ioii of tlie aromatic coi;criitrute froin experiment 4D (iii:u~kedS in Figure 4 ) are s h o ~ v n , \r.i(h the espcriinci:t iwing lwrformed a t rooin tenipernture in colunin 20,\~lLic1i Lias a frac-
-
-
0
40
60
PERCEUTAGE B Y VOLUME
100
INDUSTRIAL AND ENGINEERING CHEMISTRY
2228
I
-I-
;
1
umes of charge and length of column of adsorbent, rc$pcctii for experiment A , 0.25 liter, 1.98 meters; B , 0.5 liter, 3.95 me C, 1 .O liter, 7.90 meters. The separation of the parafin-cyi. opriraffiii portion from the aromatic portions is substnntinlly tlit. snnic i n 311 three esperiments. The separation of the mononuclew aroniatics from the polynuclear aromatics is improved with inC I ~ T in . ~ length of the column of adsorbent, bccsuse of the fiictor of lioldug h o m i n g less important. The effect of chaiiging the diameter of the frnctiounting ~ i t the h ratio of the total length of packed section t o thr. Ir~iigth of coluniri occupii,d by t h e ninterial being fractionatrd 1)ciiig Icc,~)! coriatnnt, is illustrated in Figure 9. This figure shonr tliv rc,aiiltof t w o espcriments on the separntioii of the gas-oil, perforincd :it room tcmper:iture in columns 7 and 1, nhich have fractioi1:itirig sections 7.0 meters in length and 1.0 and 1.9 cin. in diameter, r('spectively. T h e volumes of the material charged in these t i v o (7speriments ]yere in liters, as f o l l o ~ s : for enperinlent A , 0.78: R. 0.25. The rcsults of the two esperinients are substanti:illy idcntical and intlicnte that no significant amount of channeling in the flon- occurs n-ith the diameter increased to 1.9 em. The t otxl hytlroc:irl.)on portion nf the filtrate is taken as 100%. The effect of changing the temperature of operation, \ v i t h :ill other factors being kept constant, is shown in Figure 10. This figire gives the results of three experiments on the sepat'ation of gai-oil by adsorption, performed in columns 1, 2, and 3, which have fractionntirig sections 16 meters in length, with t h t ~charge in each experiment being 1.0 liter in volume arid witli t h e tc'inperutures being 25", 5 2 " , and 80" C., for esperimcnts A , R , :ind C . i,espectively. The separation of the paraffin-eycloparaffiu portion from the aromatic portion is substantially the same a t the tlirce temperatures. The fractionation of the paraffin-cycloparaffiii portion itself is substantially the same a t the three tempwaturw.
-
, I
t q z
142
r
7
0
100
200
Vol. 41, No. 10
300
VOLUME OF HYDROCARBON IN ML
Figure 6. Separation of the Paraffin-Cycloparaffin Portion of the Gas-Oil by Adsorption in Column 16 Meters i n Length
CHAhGE IN LE\S-d
I,
OF COLUMN
w ISC
I Figure 7. Separation of Tail Portion of the Aromatic Concentrate i n a 1.25-Meter
Column
0
I
I 20
I
I 40
1
I 6C
I
I 63
I
I
I
30
PERCENTAGE BY VOLClllE
Figure 8.
Separation of the Gas-Oil by Adsorption i n Columns with Different Lengths of Packed Section
INDUSTRIAL AND ENGINEERING CHEMISTRY
October 1949
2229 DISCUSSlON
C H A N G E IN COLUMN DIAMETER
C'
rD
I 3
I
-.
I
L"
!
1
I
I
-
.~
I
E..
63
43
C15223Eh-
I
I 30
-!
DF?CENTAGE 6 Y VOLUME
Figure 9.
Separation of Gas-Oil by Adsorption in Two Columns of Different Diameter
1 , increase in the temperature of operation does iniprove the separation of the iiionoriucleirr aromatics from the po1ynucle:ir aromatics. Tlic total hydroeai,bon portion of the filtrateis taken as 100%.
I
I
I
1
I
,
I
153
1
%
6
CHANGE IN
SEPARATION OF WAX FRACTION O F PETROLEUM
Figure 11 gives t h e rewlts of thc. separation by adeorption oi a charge, in liquid form, of 100 ml. (80 grams) of the TWX fraction of petrolruni, n-ith the esperimerit beirig performed a t a temperaturt' of 85' C. in column 1 1 , n-hich has a fractionating section 7.9 meters in length. These results indicate that the was fraction of petroleuni can be separatrd in a singlepass operation into tlTo portions, one of which consists iilriiost entirely of paraffins :rnd the other largely of cycloparaffins. I n addition to Pome crystalline material the cycloparaffin concentrate appeared to contain t h e greater part of the oily constituents present in the original wax fraction.
I
The results of this irivestigation are sunimarized as follows: The wax fraction of pctroleum may be separatecl by adsorption in a single-pass operation into tn-o portions, one consisting almost cmtiroly of paraffins and the other coiisisting largely of e)-cloparaffins. The gas-oil fraction of' petroleum may lie separatrd by atlsorption in a single-pass operation into t h e e portion-iiamcly, a mixture of paraffins and eycloparaffins (nnpht2icries). a portion n-hich is largc,l,v mononuclear aromatics, and otic' Jvhic-h is largcly polynuclear aromatics. Increase in thc tvmpc,rature of operation from 25" to 52" t o 80" C., in the separation of the gas-oil, has little c,fft>ct on thc. st'parntion of the paraffiri-cvcloparaffin portion from thcl aromatic portion, but, d o e h improve the separation of the nionoiiuclear aromatics from t h r polynuclear aromatics. Increase in the diameter of the column of adsorbent from 1.0 to 1.9 em. produces no signifi-
TEMPERATURE 155
x
N
+ a
0
En z L U ' X
e 2
2
cc LL w
(L
I45
0
20
40
60
80
100
PERCENTAGE BY VOLUME
Figure 10.
Separation of Gas-Oil by Adsorption a t Different Temperatures
INDUSTRIAL AND ENGINEERING CHEMISTRY
2230 I
I
i
I
I
! rtstical 7 stages of sepsration by adsorption roquired
-
WAX
__
CYCLCC:"tFCY'
-
~- !I
, ~
.
1
1
..
-I
----
-
~
-
-ORIGINAL ._ _.._ - . .- .-
~
4
14
-- -
-
~
------
I
~~
.~
--I
I
-
.
~--
'
PA??FF hS
1
_. I
I
;1 i
;
7 8
-
I
Vol. 41, No. 10
to produce the desired fractionation of the given coniponents. For a given adsorbent, these stagee will corrresporid to a given length, L, of fraclionsting section. Knowing the quantity of niaterial to be processed in one batch, the crosssectional area of the fractionating section may then be calculated. (For practical operation, the diameter of a n y one fractionating section should be less than that at which a significant amount of channeling of the flow of liquid may occur. The required cross-sectional area may be ol,tained by using two or more similar tubes in parallel.) The foregoing length, L , of fractionatirig section is the minimum length of column of adsorbent required. It is then required to dete1,rnine what additional length, r L , is required to yic.ld adcquatc reflux in the cylindrical zone of material being fractionated. The additional l(,ngtli, xL, of column of adsorbent may be an actual additional length of the same fractionating
-_--A 1 section packed
with the same adsorbent or, as mentioned previously, a n equivalent flow of fresh adsorbent upward through the stationary Figure 11. Separation of Wax Fraction by Adsorption zone of material being fractionated. While no quantitative data are available, i t is estimated t h a t the additional length, zL, may be in the range fro:n 1OL to 50L. indicates no significant amount of channeling a t thc 1argt.r cliani.kt the present time, no exact data are available for a suitable eter. known pair of components r t p r d i n g the coinposition of the solid The process of fractionation by adsorption-operatiiig 011 difadsorbed phase as a function of the colnposition of the liquid ferences in adsorbability of the components involved--used acphase in thcrmodynarnic equilibrium with the solid adsorbed cording to the method described in this and the two preceding rephase. It is hoped that such data may Soon become available. ports from this laboratory ( 1 , g), is analogous to the process of fractionation by regular distillation, operating on differerices in ACKNOW LEDCM ENT volatility of the components involved, used in a distilling column The authors wish tO express their appreCiatio[l to E. E. AiyreS of sufficient length SO that all of the charge is resident in the fratthrough whose courtesy the fractionation of all of the gas-oil wap tionating section. performed b y the Gulf Re rch and DeveloPmeIlt CompallY. I n the case of fractionation by distillation, involving thermoPittsburgh, Pa. dynamic equilibrium between the gaseous and liquid phases, the .~ reflux flow,-or interchange of material to provide opportunity for LITERATURE CITED the molecules t o reach thermodynamic equilibrium, is provided (1) hlair, B. J., J . Research S a t l . Bur. Standards, 34, 435 (1945). by the flow of vapor material upward as a result of a difference in ( 2 ) hlair, B. J., Gaboriault, 8 . L., and Rossini, F. D., IND. ENG pressure from the bottom (higher pressure) to the top (lower presCHEM.,39, 1072 (1947). (3) Rlair, B. J., Schicktana, S. T., and Rose, F. W., Jr., J . Research sure), the condensation of the vapors to liquid in the condenser S a t l . Bur. Standards, 15, 557 (1935). at the top of the column, a n d the return flow of the liquid down(4) Mair, B. J., and Streiff, A. J., Ibid.,24, 395 (1940). ward by gravity. (5) Ibid.,27, 343 (1941). I n the case of fractionation by adsorption, involving, as iri the (6) Mair. B. J . , and Willingham, C. B., ISD. ENG.CHEM.,28, 1452 (1936). present method, thermodynamic equilibrium between the liquid (7) hlnir, B. J., and Willingham, C. B., J . Research NdZ. Bur. Standphase and the solid adsorbed phase, the material to be fractionurds, 17, 923 (1936). ated is all resident in a cylindrical zone in the fractionating scc(8) Rossini, F. D.. Oil Gas J . , 37, 141 (1938). tion. The reflux, or interchange of molecules to obtain equilib(9) Iiossini, F. D., Proc. Am. PetroleumInst., 19, 111, 99 (1938). (10) Rossini, F.D., Refiner Natural Gasoline N f r . , 17, 557 (1938). rium, may be obtained either by moving fresh adsorbent upward (11) Rossini, I?. D., and Xlair, B. J.. OilGus J . , 40, 129 (1941). through the cylindrical zone of material with a suitable desorbent (12) Iiosini, F.D., and Rlair, B. J., Proc. Am. Petroleum Inst., 22. a t the top of the zone t o retain in the zone the material being 111, 7 (1921). fractionated, or by moving the cylindrical zone of material d o r m 113) Rosiiii, F. D., and Mair, B. J., Refiner Natural Gasoline Mf... 20, 494 (1941). ward over fresh adsorbent by gravity flow with or without the benefit of additional pressure, with a suitable desorbent a t the KECEIYED J u l y 6, 19.13. Presented before t h e Division of Petroleurn top of the zone of material being fractionated. The relative rate Chemintry a t t h e 114th Meeting of t h e AVERICANCHEMICALSOCIETY, 5t. Louis, RIo. This investigation was performed as p a r t of t h e work of of flow of the adsorbent and the material being fractionated t h e American Petroleum I n s t i t u t e Research Project 6 a t t h e National Bureau needs to be fast enough to avoid backward diffusion of the compoof Standards. nents being fractionated, such as might occur if the system were stationary. I n the batch fractionation of a given quantity of a givcin rniuture of components by this method of adsorption, one iicwls tc have, first, a sufficient separating power, or number of cquivnlvnt stages of separation required to effect the desired frixtionation of the given components, and, secondly, a sufficient capacity in the fractionating section to handle the given charge. In principle, one may calculate the number of equivalent theoI
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