The Cracking of Cottonseed Oil GUSTAVEGLOFF AND J. C. MORRELL Universal Oil Products Company, Chicago, Ill.
T
HE cracking of oils for motor fuels has been applied
almost exclusively to hydrocarbon oils, largely those derived from petroleum. It is of considerable interest to study the behavior of cottonseed oil, as representative of the fatty or glyceride oils, when subjected to cracking conditions. While economic conditions forbid the use of this oil for making gasoline at the present time, future occasion, particularly a national emergency, might necessitate the production of motor fuel from such oils. Its use as a source of motor fuel might also be practical in such countries as Turkey and Egypt where large supplies of cottonseed oil are available and the price of gasoline is high. Mailhe (3) has produced materials within the boiling range of motor fuel which he states are similar to American gasoline by the catalytic pyrolysis of cottonseed oil, employing fused zinc chloride as catalyst. He reports that the products of such catalytic pyrolysis of vegetable oils are primarily ethylene hydrocarbons having a yellow color and strong odor. Upon further treatment with zinc chloride, the unpolymerized oils distilling between 240" and 280" C. lose their yellow color and sharp odor, becoming colorless and fluorescent. Water, acrolein, and a lean gas are formed in addition to the oil product. Gallo and Correlli (2) subjected vegetable oils to treatment with superheated steam in the presence of alkaline earths and passed the vapors produced thereby over pumice impregnated with ferrous oxide at a temperature of 550" C. The product thus produced was hydrogenated a t a temperature of 200-250" C., employing a nickel catalyst. Sixty to sixty-five per cent of a yellowish brown, volatile, fluorescent liquid, boiling from 45" to 350" C., leaving 5 per cent of a tarry residue, was produced. Waterman and Perquin (4) studied the decomposition of cottonseed oil in a closed vessel a t a temperature of 450" C. They found that cottonseed oil loses its oxygen almost quantitatively as carbon monoxide, carbon dioxide, and water, when heated with hydrogen in an autoclave a t 450" C. The remaining product consists largely of a hydrocarbon mixture with a high percentage within gasoline boiling range. Cracking of cottonseed oil a t elevated temperature under pressure yields over 54 per cent of refined gasoline. The properties of the cottonseed used in this study are as follows: Sp. gr. at 1 5 . V C. Acid va+e Polenski value % Reichert-Meis&number
0.823 2.0
1.0
0.69
Glycerides, % Sulfur, Q water& Coke, yweight
96
0:i 2.6
A. 8. T, M. 1oO-CC. DISTILLATION
DISTILLED OVER
TEMP.
%
c.
Initial 10 20 30
O
237 302 314 31s
DISTILLED
DISTILLED
OVER
TEMP.
%
c.
%
c.
40
317 328 336 351
SO 90 95
363 372 366 371
KO 60 70
OVER
End point
TEMP.
cooled condenser and a receiver. The still was equipped with a pressure gage and wells for thermometers, The pressure still was charged with 800 cc. cottonseed oil. The still was heated until a self-generated vapor pressure of 9.5 kg. per sq. cm. was reached, a t which point the gas release valve was opened on the distillate receiver. The heat application was continued until 485" C. was reached. Above this temperature no further distillate appeared, and a residue of coke remained in the pressure still. The products were gas, distillate oil, coke, and water. PRODUCTS OF CRACKING The summary of the cracking results is as follows: Pressure distillate: % of charge
71.1 0.772 5.3 23.6 40 (116) 916 (163)
SD.ur.
Wafer; % Coke, gas, and loss % of charge Coke, Ib. 42 gal bdl of charge (grams/liter) Gas, cu. /t./bbl. bf charge (liters/liter) Motor fuel: &,o;;harge
58.7 0.761 46 225
Initial b. p. C End b. _ D.. . C. Gas oil, Diesel, or furnace oil: % of charge Sp. gr.
10.6 0.912
PRESSURE DISTILLATE OIL. Analysis of the pressure distillate showed a saponification number of 40, an ester value of 7, and an acid value of 33; the acid and ester volume were, respectively, 6 and 2 per cent of the pressure distillate. This indicated that the glycerides were decomposed into hydrocarbons, free and combined acids of relatively low molecular weight, and water. The pressure distillate containing the motor fuel and Diesel or gas oil was fractionated, using an 800-cc. charge and a Hempel column filled with glass beads: Sp. gr. 0.7749 Initial b. p , , a. C. 34 DISTILLED DISTILLED DISTILLED OVER TEMP. OYER TEMP. OVEB TBMP.
%
c.
%
c.
10 20 30
62 86 109
40 50 60
130 151 173
% 70 75 82.6
O
c.
197 210 229
The yield of unrefined motor fuel of gasoline boiling range was 58.7 per cent of the cottonseed oil. REFINING OF CRACKED DISTILLATE.The pressure distillate was treated with approximately 1 per cent by volume of 93 per cent sulfuric acid. After settling, the sludge was withdrawn, and the oil was water-washed, neutralized with sodium hydroxide, and distilled with steam into motor fuel and pressure distillate bottoms. For complete removal of the esters and fatty acids, refluxing with strong sodium hydroxide solutions, prior to acid treatment, is required , although this is not necessary to refine the gasoline commer cially The sulfuric acid solution loss was 2 per cent of the pressure distillate oil with a polymerization loss of 1.8 per cent. Upon distillation of the refined pressure distillate into motorfuel pressure distillate bottoms there was a loss of 2 per cent. CRACKED MOTORFUEL. The properties of the finished motor fuel were as follows:
.
The oil was cracked by the nonresiduum method of operation at a pressure of 9.5 kg. per sq. cm. (135 pounds per square inch) and over a temperature range of 445' to 488 " C. The apparatus employed consisted of a still, 8 inches (20.3 cm.) in diameter, made from a machined flanged drop forging and companion flanged head with tongue and groove closure; a vapor line with pressure control valve; a water-
1426
?%:'Saybolt Doctor
0,761 30+
Sweet
Corrosion Sulfur, % Gum, mg. per 100 cc.
Negative
0.01 33
9%
0
c.
10
m
" c.
9%
83 76
S
60 8n khd b. p
s9
187 201
A hydrocarbon annlysis ( 1 ) of tho refined motor fuel
dhomed the following percentages: H r o a u c ~ a a o nG ~ o u r P&r*(F"* UnshtilrsLer Naphtheuee Arornst,lcs
Y'
:17., 27.1
..
do. IF. UlrnlrEo OYER
% 10
20 80 ti)
'r*MP.
C. 239 247
0
261 257
Initial b.
0.912 OVEB
%
so
80 70
of motor fuel. 0.. *
C.
TtihlP.
oYBB
TEMP,
c,
263 269
80
300
282
95
883
c.
90
,"
90.18 1.20
IsopBntnne
Pentme
GAS
5.2
+ Iwzbei paraifi~a
riydroaen
1 . g Carbon munorids 2 . 9 Carbon dioxide 0 . 8 Nitrogen (by diaerenoei 2.1
% 8.8 2.3 8.0 5.8 6.7 8.4
W-nTEn. The water produced by converdion of the cottonseed oil showed a relatively high acidity of 3.6 normality. Aldehydes were also present in sinall quantities.
LITERATUBE CITED
%
0
70
s s . 2 1'r"irYlene 12.2 1 3 Uutsdiene
236
niiifllrsEo
DIBT'LLD"
G*e
Butane Isubutane
PHESBUHC: L)ISrILLATE U O P ~ P ~ M The S . residue left after the motor fuel was distilled from the refined pressure d i e tillate was suitable for Diesel or gas oil, or could be cracked
liixed oaibon Ash
CRACKED GAS. ' h e eas uroduced bv cracking cottonseed oil wits analyzed by t& ljurrell and "I'odbieinLk methods and tlie results combined showed the following percentages of components: Metiism Etilsrla Propane
R.!1 25.9
in % second operation to increase the +d This oil had the following properties:
,"
0.16 8.48
*l
