INDUSTRIAL A N D ENGINEERING CHEMISTRY
1042
Vol. 19. No. 9
Solubility of Paraffin W a x in Oil By F. W. Sullivan, Jr., W. J. McGill, and August French STANDARD OIL COMPANY (INDIANA), WHITIKO,IND.
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Paraffin waxes of 111" F., (43.9'C.), 125" F. (51.7"C.), midcontinent, and hence its and 145' F. (63.8' C.) Saybolt melting points and consolubilities of paraffin value is doubtful for calculataining relatively few individual hydrocarbons have wax in petroleum oils tions involving this crude, been obtained by the repeated fractionation of 125' F. a t various temperatures, and Preparation of Waxes (51.7' C.) Saybolt melting point commercial paraffin of the effect of viscosity of wax from midcontinent crude. The solubilities of solvent and the melting point The waxes used in these these fractionated waxes and of the 125' F. (51.7' C.) of the wax upon solubility, is experiments were f r a c t i o n s melting point commercial wax itself have been deof considerable practical value from the vacuum distillation termined in petroleum ether (boiling point 21.0° to in filter-pressing wax distilof 50 liters of 125" F. (51.7' 82.0' C.) and in a number of midcontinent petroleum lates to remove the wax. It C.) melting point wax oboils of varying viscosities. Some of the oils represent is also useful in making caltained from the wax refinery. narrow cuts from a fractional vacuum distillation; c u l a t i o n s involving the reThis wax had been sweated others are blends of oils of widely separated viscosities. f r i g e r a t i o n of wax-bearing from intermediates, and conSolubilities were determined a t various concentrations oils. Solubility data in the sequently did not contain the and curves were constructed showing the variation of literature consist principally highest melting waxes sepathese solubilities with temperature, viscosity, and of figures for supposedly pure rated in pressing. melting point. h y d r o c a r b o n s from either -ffnr -- the fractional distillasynthetic or natural sources, tion of the wax, a still of 10 in the usual organic solvents. Such figures have little or no liters capacity was made. The body of the still consisted direct value in plant operation. Prac&ally all of the meager of a 9-inch (23-cm.) length of 10-inch (25-cm.) pipe with information upon solubilities in petroleum oils which is avail- plates welded at either end and appropriate openings for able was obtained on oils and waxes from crudes other than charging and draining. The fractionating column was a Z1/2-inch (6-cm.) pipe 18 inches (46 cm.) long, filled with 1 Presented before the Division of Petroleum Chemistry at the73rd Meeting of the American Chemical Society, Richmond, Va., April 11 t o 16, 1927. plates of 3/8-inch (1-cm.) mesh wire screen spot-welded a t 2-inch (5-cm.) intervals on a thin rod running through the center of the tower. An iron pipe '/z inch (1.3 cm.) in diameter and 30 inches (76 cm.) long served M an air condenser. The receiving system consisted of a 500-c~.balloon Aaek with a stopcock outlet. Two Cenco oil pumps were used to maintain the vacuum at 5 111111. When all the fittings had been carefully tightened after the threads had been painted with graphite paste, a 5-mm. vacuum was readily maintained under operating conditions. I n fact, one pump was at times sufficient. From one to four Meker burners supplied the heat. The tower was wound with electrical resistance wire. It was found convenient to heat the tower a t the beginning of the run, both tosave time and to break any foaming caused a t the beginning of the distillation by the evolution of gas and moisture from the wax on the application of heat and vacuum. After the distillation had once started
KNOWLEDGE of the
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September, 1927
I L D U S T R I A LAAVD ENGINEERING CHELVISTR Y I
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SOLUBILITY c+ IIlF1438CIMP PARAFFINE W M
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SAYBCCT IOOF VECc)51TY OF OIL %LENTS 3
ali heating of the tower was found to be unnecessary and was therefore discontinued. Five such distillations of 10-liter charges of 125" F. (51.7' C.) melting point refined wax were made. I n general, the melting points of like cuts checked each other fairly well. The 0-10 per cent and 10-20 per cent cuts from the five distillations were combined to give 10 liters of material to be distilled B second time. Likewise the 20-40 per cent cuts, the 40-60 per cent cuts, and 60-80 per cent cuts were combined to give 10 liters of material for the second fractionation. The 80-90 per cent cuts combined gave another 5 liters. Thus six more distillations were made. Ten per cent cuts were taken again. These cuts represented 2 per cent of the total amount of wax charged. Since a fairly close cut wax was desired and since at about 125' F. (51.7' C.) melting point the melting points of the cuts were closer to each other than a t the very beginning or a t the end of the distillation, a selection of cuts was made from the second fractionation and these were distilled in a 5-liter vacuum still. From these cuts a n amount of quite pure 12.5' F. (51.7' C.) melting point wax was prepared. A sample of 111' F. (43.9' C.) melting point wax was made by a recrystallization of twice-distilled low melting point cuts from ethylmethyl ketone. A sample of 145' F. (62.8' C . ) melting point wax was selected from the higher melting fractions of the second fractionation. The boiling point range of these fractionated waxes was 5' C. a t 5 mm. pressure. Their cooling curves are compared in Plate XI1 with the cooling curve for the sample of 125' F. (51.7' C.) melting point commercial wax whose solubility was also determined.
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PLATE V I SOLUWLITY OF IPST
