Colloid systems and wetting agents; subcombinations thereof; pro – Continuous liquid or supercritical phase: colloid systems;... – Aqueous continuous liquid phase and discontinuous phase...
Reexamination Certificate
1999-01-22
2002-10-01
Lovering, Richard D. (Department: 1712)
Colloid systems and wetting agents; subcombinations thereof; pro
Continuous liquid or supercritical phase: colloid systems;...
Aqueous continuous liquid phase and discontinuous phase...
C044S301000, C044S302000, C137S013000, C516S077000
Reexamination Certificate
active
06458855
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to stable, macro emulsions of hydrocarbons in water derived from the Fischer-Tropsch process.
BACKGROUND OF THE INVENTION
Hydrocarbon-water emulsions are well known and have a variety of uses, e.g., as hydrocarbon transport mechanisms, such as through pipelines or as fuels, e.g., for power plants or internal combustion engines. These emulsions are generally described as macro emulsions, that is, the emulsion is cloudy or opaque as compared to micro emulsions that are clear, translucent, and thermodynamically stable because of the higher level of surfactant used in preparing micro-emulsions.
While aqueous fuel emulsions are known to reduce pollutants when burned as fuels, the methods for making these emulsions and the materials used in preparing the emulsions, such as surfactants and co-solvents, e.g., alcohols, can be expensive. Further, the stability of known emulsions is usually rather weak, particularly when low levels of surfactants are used in preparing the emulsions.
Consequently, there is a need for stable, macro emulsions that use less surfactants or co-solvents, or less costly materials in the preparation of the emulsions. For purposes of this invention, stability of macro emulsions is generally defined as the degree of separation occurring during a twenty-four hour period, usually the first twenty-four hour period after forming the emulsion.
SUMMARY OF THE INVENTION
In accordance with this invention a stable, macro emulsion wherein water is the continuous phase is provided and comprises Fischer-Tropsch process water, a hydrocarbon and a non-ionic surfactant. Preferably, the emulsion is prepared in the substantial absence, e.g., ≦2.0 wt %, preferably ≦1.0 wt % or complete absence of the addition of a co-solvent, e.g., alcohols, and preferably in the substantial absence of co-solvent, that is, Fischer-Tropsch process water may contain small amounts of oxygenates, including alcohols; these oxygenates make up less oxygenates than would be present if a co-solvent was included in the emulsion. Generally, the alcohol content of Fischer-Tropsch process water is less that about 2 wt % based on the process water, more preferably less than about 1.5 wt % based on the process water.
The macro-emulsions that are subject of this invention are generally easier to prepare and more stable that the corresponding emulsion with, for example, distilled water or tap water. Using the Fischer-Tropsch process water takes advantage-of the naturally occurring chemicals in the Fischer-Tropsch process water to reduce the amount of surfactant required to prepare stable emulsions.
PREFERRED EMBODIMENTS
The Fischer-Tropsch process can be described as the hydrogenation of carbon monoxide over a suitable catalyst. Nevertheless, regardless of the non-shifting catalyst employed, water is a product of the reaction.
2nH
2
+nCO→C
n
H
2n+2
+nH
2
O
The Fischer-Tropsch process -water, preferably from a non-shifting process, separated from the light gases and C
5
+product can generically be described as (and in which oxygenates are preferably ≦2 wt %, more preferably less than about 1 wt %):
C
1
-C
12
alcohols
0.05-2 wt %, preferably 0.05-1.2 wt %
C
2
-C
6
acids
0-50 wppm
C
2
-C
6
Ketones, aldehydes
0-50 wppm
acetates
other oxygenates
0-500 wppm
The Fischer-Tropsch process is well known to those skilled in the art, see for example, U.S. Pat. Nos. 5,348,982 and 5,545,674 incorporated herein by reference and typically involves the reaction of hydrogen and carbon monoxide in a molar ratio of about 0.5/1 to 4/1, preferably 1.5/1 to 2.5/1, at temperatures of about 175-400° C., preferably about 180°-240°, at pressures of 1-100 bar, preferably about 10-50 bar, in the presence of a Fischer-Tropsch catalyst, generally a supported or unsupported Group VIII, non-noble metal, e.g., iron, nickel, ruthenium, cobalt and with or without a promoter, e.g. ruthenium, rhenium, hafnium; platinum, palladium, zirconium, titanium. Supports, when used, can be refractory metal oxides such as Group IVB, e.g., titania, zirconia, or silica, alumina, or silica-alumina. A preferred catalyst comprises a non-shifting catalyst, e.g., cobalt or ruthenium, preferably cobalt with rhenium or zirconium as a promoter, preferably cobalt and rhenium supported on silica or titania, preferably titania. The Fischer-Tropsch liquids, i.e., C
5
+, preferably C
10
+ are recovered and light gases, e.g., unreacted hydrogen and CO, C
1
to C
3
or C
4
and water are separated from the hydrocarbons. The water is then recovered by conventional means, e.g., separation.
The emulsions of the invention are formed by conventional emulsion technology, that is, subjecting a mixture of the hydrocarbon, water and surfactant to sufficient shearing, as in a commercial blender or its equivalent for a period of time sufficient for forming the emulsion, e.g., generally a few seconds. For general emulsion information, see generally, “Colloidal Systems and Interfaces”, S. Ross and I. D. Morrison, J. W. Wiley, NY, 1988.
The hydrocarbons that may be emulsified-by the Fischer-Tropsch process water include any materials whether liquid or solid at room temperature, and boiling between about C
4
and 1050° F.+, preferably C
4-
700° F. These materials my be further characterized as fuels: for example, naphthas boiling in the range of about C
4
-320° F., preferably C
5
-320° F., water emulsions of which may be used as power plant fuels; transportation fuels, such as jet fuels boiling in the range of about 250-575° F., preferably 300-550° F., and diesel fuels boiling in the range of about 250-700° F., preferably 320-700° F.
The hydrocarbons may be obtained from conventional petroleum sources, shale (kerogen), Fischer-Tropsch hydrocarbons, tar sands (bitumen), and even coal liquids. Preferred sources are petroleum, kerosene and Fischer-Tropsch hydrocarbons that may or May not be hydroisomerized.
Hydroisomerization conditions for Fischer-Tropsch derived hydrocarbons are well known to those skilled in the art. Generally, the conditions include:
CONDITION
BROAD
PREFERRED
Temperature, ° F.
300-900
550-750
(149-482° C.)
(288-399° C.)
Total pressure, psig
300-2500
300-1500
Hydrogen Treat Rate, SCF/B
500-5000
2000-4000
Catalysts useful in Hydroisomerization are typically bifunctional in nature containing an acid function as well as a hydrogenation component. A hydrocracking suppressant may also be added. The hydrocracking suppressant may be either a Group 1B metal, e.g., preferably copper, in amounts of about 0.1-10 wt %, or a source of sulfur, or both. The source of sulfur can be provided by presulfiding the catalyst by known methods, for example, by treatment with hydrogen sulfide until breakthrough occurs.
The hydrogenation component may be a Group VIII metal, either noble or non-noble metal. The preferred non-noble metals include nickel, cobalt, or iron, preferably nickel or cobalt, more preferably cobalt. The Group VIII metal is usually present in catalytically effective amounts, that is, ranging from 0.1 to 20 wt %. Preferably, a Group VI metal is incorporated into the catalyst, e.g., molybdenum, in amounts of about 1-20 wt %.
The acid functionality can be furnished by a support with which the catalytic metal or metals can be composited in well known methods. The support can be any refractory oxide or mixture of refractory oxides or zeolites or mixtures thereof. Preferred supports include silica, alumina, silica-alumina, silica-alumina-phosphates, titania, zirconia, vanadia and other Group III, IV, V or VI oxides, as well as Y sieves, such as ultra stable Y sieves. Preferred supports include alumina and silica-alumina, more preferably silica-alumina where the silica concentration of the bulk support is less than about 50 wt %, preferably less than about 35 wt %, more preferably 15-30 wt %. When alumina is used as the support, small amounts of chlorine or fluorine may be incorporated into the support to provide the acid functionality.
A preferred support catalyst has surface areas in th
Ansell Loren L.
Berlowitz Paul J.
Chakrabaty Tapan
Wittenbrink Robert J.
Brumlik Charles J.
Exxon Research and Engineering Company
Lovering Richard D.
Simon Jay S.
LandOfFree
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