Process of Purifying Paraffin. Page: 1 of 2
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UNTED__STATESPATENT OFFIE.
ALMER M. McAFEE, OF PORT ARTHUR, TEXAS, ASSIGNOR TO GULF REFINING COMPANY,
OF PITTSBURGS, PENNSYLVANIA, A CORPORATION OF TEXAS.
PROCESS OF PURIFYING PARAFFIlT.Specifioation of Letters Patent. Patented Aug. 27, 1918.
Application fled June 10, 1918. Serial No. 239,291.To all whom it may concern:
Be it known that I, ALMER M. MCAFEE,
a citizen of the United States, residing at
Port Arthur, in the county of Jefferson and
5 State of Texas, have invented certain new
and useful Improvements- in Processes of
Purifying Paraffin, of which the following
is a specification.
This invention relates to processes of puri-
10 fying paraffin; and it comprises a process
wherein ' paraffin wax is stabilized and
bleached by a' treatment with anhydrous
aluminum chlorid, the paraffin wax, or mate-
rial containing the same, being warmed to a
15 temperature sufficient to make it fluid, a
small amount of anhydrous aluminum
chlorid, say '2 to 5 per cent., added, the
mixture vigorously agitated, and the alumi-
num chloride renioved; all as more fully
20 hereinafter set forth and as claimed.
Paraffin wax is. composed of members of
the paraffin series of hydrocarbons occur-
ring in petroleum which are solid at ordi-
nary temperatures. There are many of
25 these hydrocarbons and they vary consider-
ably in melting point and commerical
paraffin wax may have very different points
of softening and melting according to its
constituents. A number of processes are in.
30 use for recovering paraffin from petroleum.
Where the crude petroleum oil is distilled
with use of "bottom steam" (steam led di-
rectly into .the oil in the still), the latter
portions of the oily distillate separate crys-
35 tals of paraffin on cooling. Where a crack-
ing distillation is. used, a period of destruc-
tive distillation is resorted. to after the
iaphtha and gasolene are distilled over, giv-
ing cracked burning oils. The residual oily
40 material in 'the. still which in this case is
known as tar or residuum is 'then -distilled
in special stills down to a residue of coke,
giving an.oily distillate from which paraf-
fin separates abundantly on cooling. What-
45 ever the source of the paraffin-carrying .oil,
it -is customary to cool it to ,a low tempera-
ture to crystallize out as .much paraffin as
desired and 'then drain or press. The
crystallized paraffin- so obtained is melted,
50 re-cooled and the 'separating crystals once
more drained or pressed and so on. As
many crystallizations may be made as is
necessary to 6btin a product of the de-
sired 'purity. :I4 this crystallization op-
55 portunity is afforded of course to obtainvarious grades of crystallized paraffin of
different melting or softening points by frac-
tional separation; that is by cooling some-
what, separating the crop of crystals
formed, re-cooling and so on: 60
The paraffin wax thus obtained is usually
purified in the usual ways adapted for treat-
ing petroleum materials, in order to decolor-
ize it, boneblack, fullers' earth, etc., are often
employed. By these purifying methods it 65
may be obtained brilliantly white and ap-
parently of a considerable degree of purity,
but many of these white paraffins however
on standing exposed to air and light develop
a yellow contamination. This tendency to 7o.
become yellow lowers the market grade of
any paraffin considerably. The tendency to
develop color is apparently not inherent in
the paraffin itself but in impurities not re-
moved- by the ordinary methods of purifi- 75
cation. 'Turning yellow is apparently due
to a retention of more or less of the oil from
which the paraffin was separated. This oil,
at least in some cases, is a badly cracked
material,; it is largely of unsaturated nature. 80
It is possibly because of this unsaturated
nature that it tends to change on exposure
to light and air; unsaturated hydrocarbons
being much more reactive under such cir-
cumstances than the saturated hydrocarbons, us
such as paraffin.
I have found that this tendency to' turn
yellow on the part of the commercial paraf-
fin wax may be simply and-easily removed
by melting the paraffin and agitating vigor- 90
ously for a few hours, say 2 to 6, hours, with
a small amount of a metallic halid such as
aluminum chlorid, say 2 to 5 per cent. The
temperature at which this is done should not
be much higher than suffices for melting the 95
particular paraffin wax. A temperature of
1500 F. ordinarily does very well. The tem-
peratre may of course be carried up. some-
what higher, say to 212* F. ;. but I find tem-
peratutes around 150 are better. The ac- 100
tion of the aluminum chlorid in producing -
this stabilizing effect on the paraffin is of
a more or less uncertain nature but I am of
the opinion that it operates chiefly .by con-
verting the unsaturated oily bodies present 105
into saturated bodies. After the aluminum
chlorid has acted on the paiaffin for the de-
sired length of time, the warm mixture is
allowed to stand quietly for a time with the
result of the deposition of most iof the 1101,277,092.
No Drawing,
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McAfee, Almer M. Process of Purifying Paraffin., patent, August 27, 1918; [Washington D.C.]. (https://texashistory.unt.edu/ark:/67531/metapth1258449/m1/1/: accessed June 22, 2024), University of North Texas Libraries, The Portal to Texas History, https://texashistory.unt.edu.; crediting UNT Libraries Government Documents Department.