Title:
Re-refining used automotive lubricating oil
United States Patent 3919076
Abstract:
This patent describes a process for re-refining waste automotive lubricating oil and similar waste hydrocarbon oils, which employs a novel sequence of steps including treatment with a saturated hydrocarbon solvent, followed by vacuum distillation, followed by catalytic hydrogenation.
US Patent References:
/1242667.html
Elliott - October 1917 - 1242667
Process for removing engine produced contaminants from used lubricating oil
Fiedler et al. - February 1965 - 3169917
/1242667.html
Elliott - October 1917 - 1242667
Process for removing engine produced contaminants from used lubricating oil
Fiedler et al. - February 1965 - 3169917
Inventors:
Cutler, Louis E. (Merion, PA)
Cutler, Edward T. (Merion, PA)
Cutler, Edward T. (Merion, PA)
Application Number:
05/532167
Publication Date:
11/11/1975
Filing Date:
12/12/1974
View Patent Images:
Export Citation:
Assignee:
Pilot Research & Development Co. (Merion Station, PA)
Primary Class:
Other Classes:
208/184, 208/179
International Classes:
C10M175/00; C10M11/00
Field of Search:
208/179,180,184
Primary Examiner:
Gantz, Delbert E.
Assistant Examiner:
Nelson, Juanita M.
Parent Case Data:
This application is a continuation-in-part of application Ser. No. 489,779, filed July 18, 1974, and now abandoned.
Claims:
As the invention, we claim
1. A process for re-refining waste crankcase oil and similar waste hydrocarbon oils consisting of the following consecutive steps:
2. The process of claim 1 wherein the saturated hydrocarbon in step (b) is propane, employed in an amount equal to 4-6 times the volume of the dry oil at a temperature of 180°-190°F. and a pressure of 600-700 psig.
3. The process of claim 1 wherein the hydrogenation step (f) is carried out at 600°-700°F., 600-700 psig, and L.H.S.V. = 1.0.
1. A process for re-refining waste crankcase oil and similar waste hydrocarbon oils consisting of the following consecutive steps:
2. The process of claim 1 wherein the saturated hydrocarbon in step (b) is propane, employed in an amount equal to 4-6 times the volume of the dry oil at a temperature of 180°-190°F. and a pressure of 600-700 psig.
3. The process of claim 1 wherein the hydrogenation step (f) is carried out at 600°-700°F., 600-700 psig, and L.H.S.V. = 1.0.
Description:
The process of this invention is a pollution-free way to make the highest quality automotive lubricating oil at the lowest cost from waste crankcase oil (hereafter called WCCO) and similar waste hydrocarbon oils. Widespread use of the process of this invention can satisfy 25-50% of this country's automotive lube oil needs, conserve a limited natural resource, and prevent pollution.
The composition of WCCO in the United States today is:
1-6% Light ends (b.p. up to 350°F. at 760 torr)
10-15% Heavy ends (b.p. 350°-650°F. at 760 torr)
60-70% Lube stock (b.p. 650°-800°F. at 760 torr)
0-10% Bright stock (b.p. 800°-950°F. at 760 torr)
1-3% Particulates (mostly <2μ dia., principally C, Pb, P and Ca)
0-10% Water
7-15% Additives
5-8% Oil oxidation products
Previous re-refining processes have had serious difficulties because lube oil additives are difficult to remove from WCCO, and interfere with the removal of other impurities. Re-refining with sulfuric acid creates a considerable volume of acid sludge which is difficult to properly dispose of. Re-refining with any combination of caustic soda, caustic silicate, slaked lime, and deemulsifiers yields undependable results and creates a considerable amount of noxious sludge containing significant amounts of oil. Re-refining with a process whose first step is vacuum distillation creates severe equipment maintenance problems and oil loss. Re-refining with polar organic solvents such as chlorex, selecto, phenol, furfural, and various alkanol and alkanol-water mixtures is inferior to treatment with propane (the preferred solvent of this invention) because a considerable amount of lube oil is lost, 3-5 times more heat is needed in the recovery step to distill a given volume of polar solvent, and smaller amounts of WCCO impurities are removed. Refining by direct catalytic hydrogenation of dehydrated WCCO, and re-refining by propane treatment of dry WCCO followed by high temperature bauxite treatment yield finished oil of inferior quality. Re-refining by high temperature WCCO treatment, followed by clay treatment, filtration, and catalytic hydrogenation, and re-refining by propane treatment of dry WCCO followed by catalytic hydrogenation yield finished oil of satisfactory quality; but, compared to the process of this invention, hydrogenation pressure and temperature must be higher, hydrogenation L.H.S.V. must be lower, hydrogen consumption is at least doubled, hydrogenation catalyst life is reduced, larger hydrogenation capacity is required, and more fuel from external sources is required. In addition, little or no lube oil fractionation is carried out to separate the light ends, heavy ends, lube stock, and bright stock.
The process of this invention consists of the following steps:
1. Screen out large pieces of debris and dehydrate the oil.
2. Mix the dry oil with 1-15 (preferably 4-6) times its volume of a saturated hydrocarbon selected from the group consisting of ethane, propane, butane, pentane, hexane, and mixtures thereof (preferably propane). Keep the mix liquid under pressure at a temperature near but below its critical point. In the case of propane, we prefer temperatures of 180°-190°F. at 600-700 psig. Settle the mix, drain off the bottoms, and separate the clarified oil-solvent mix. The bottoms can be burned to supply process heat. A special scrubber must be used to remove heavy metal particulates from the combustion gases.
3. Strip the solvent from the clarified oil-solvent mix of step 2, condense it and store for reuse. Collect the stripped oil.
4. Vacuum distill the stripped oil of step 3 at a pressure no greater than 10 torr and a temperature no greater than 650°F., distilling over all but 10-15% of the charge stock. Fractionate the distillate. No maintenance or yield problems result from vacuum distilling this material. The vacuum bottoms can be burned to supply process heat. No special scrubber is needed.
5. Hydrogenate the condensed hot oil fractions over a catalyst consisting of one or more Group VI and/or VIII metal oxides or sulfides at 500°-800°F. (preferably 600°-700°F.), 500-1000 psig (preferably 600-700 psig), and L.H.S.V. = 0.5-2.0 (preferably 1.0).
6. Strip the hydrogenated oil fractions of hydrogen, reduction products, and light ends.
7. Cool and filter the oil.
Each step of the process of this invention is known, but the novel sequence of steps has not been stated or appreciated till now. The precipitative hydrocarbon step removes 70-80% of the original WCCO impurities. Impurities precipitated by the hydrocarbon solvent consist of high molecular weight additives, additive fragments, and oil oxidation products, plus high density particulates. The vacuum distillation step removes 10-15% of the original WCCO impurities and fractionates the oil. Impurities eliminated in the vacuum bottoms consist of medium molecular weight additives, additive fragments, and oil oxidation products, plus low molecular weight salts, acids, and colloidal solids. The hydrogenation step removes the last 10-15% of the original WCCO impurities by chemically transforming them into hydrocarbons having molecular weights equal to or less than oil, plus H 2 S, H 2 O, and NH 3 . Impurities removed by the hydrogenation step consist of low molecular weight additives, additive fragments, and oil oxidation products. The important features of the process of this invention are:
1. Each step removes a significant amount of impurities which are not easily removed by the previous step.
2. Each step removes a significant amount of impurities which are not easily removed by the step that follows.
3. All impurities are dependably removed.
4. Impurities are removed in the form of easily burned fuels.
5. Processing cost is the lowest of any known process.
6. Equipment maintenance costs are very low.
7. There is little oil loss and no pollution.
8. The finished oil is equal to or better than virgin lube oil in quality.
An example of the process of this invention follows:
A sample of WCCO was heated to 350°F. 2% light ends and water were removed. 500 ml of the dry WCCO were placed in a pressure vessel with 2500 ml of propane. The mix was shaken, heated to 190°F., and allowed to settle one hour. Then the propane bottoms, representing 12% by weight (10% by volume) of the dry WCCO, were drained out of the pressure vessel. The clarified propane-oil mix was decanted and depropanized, then the 450 ml of propane-treated oil was subjected to a nitrogen-vacuum distillation at 10 torr. The first 10% of distillate was considered to be heavy ends, the 10-90% cut (b.p. 490°-620°F. at 10 torr) was considered to be in the lube range, the last 10 % was left in the pot. The lube oil cut was hydrogenated in a pressure vessel under the following conditions:
oil:catalyst volume ratio=1:1
catalyst=Houdry HR-801 cobalt-molybdenum catalyst, 25% sulfided
temperature=650°F.
reaction time=1 hour
H 2 pressure=650 psig
Then it was lightly stripped to remove 1-2% light ends, reduction products and hydrogen, and filtered to remove catalyst fines. Properties of the finished lube oil are shown in Table 1.
Table 1 ______________________________________ Properties of WCCO and finished lube oil made by the process of this invention WCCO Finished lube ______________________________________ viscosity at 100°F. 319 SUS 170 SUS viscosity at 210°F. 59.6 SUS 44.6 SUS viscosity index 141 101 color, ASTM black 1.5 color after 16 hours at 210°F. black 2.0 - gravity at 60°F. 24.4°API 30.5°API (0.875 g/ml) flash (Cleveland Open Cup) 360°F. 445°F. fire (Cleveland Open Cup) -- 495°F. ash 1.81 less than 0.001% pour point -40°F. 15°F. T.A.N. (ASTM D664) 5.87 0.06 mg KOH/g Conradson carbon 5.20 less than 0.001% Cu strip corrosion -- passes, 1B (3 hr. at 210°F.) sulfur (ASTM D1552) 0.32 0.08% nitrogen 0.17 0.05% ______________________________________
The composition of WCCO in the United States today is:
1-6% Light ends (b.p. up to 350°F. at 760 torr)
10-15% Heavy ends (b.p. 350°-650°F. at 760 torr)
60-70% Lube stock (b.p. 650°-800°F. at 760 torr)
0-10% Bright stock (b.p. 800°-950°F. at 760 torr)
1-3% Particulates (mostly <2μ dia., principally C, Pb, P and Ca)
0-10% Water
7-15% Additives
5-8% Oil oxidation products
Previous re-refining processes have had serious difficulties because lube oil additives are difficult to remove from WCCO, and interfere with the removal of other impurities. Re-refining with sulfuric acid creates a considerable volume of acid sludge which is difficult to properly dispose of. Re-refining with any combination of caustic soda, caustic silicate, slaked lime, and deemulsifiers yields undependable results and creates a considerable amount of noxious sludge containing significant amounts of oil. Re-refining with a process whose first step is vacuum distillation creates severe equipment maintenance problems and oil loss. Re-refining with polar organic solvents such as chlorex, selecto, phenol, furfural, and various alkanol and alkanol-water mixtures is inferior to treatment with propane (the preferred solvent of this invention) because a considerable amount of lube oil is lost, 3-5 times more heat is needed in the recovery step to distill a given volume of polar solvent, and smaller amounts of WCCO impurities are removed. Refining by direct catalytic hydrogenation of dehydrated WCCO, and re-refining by propane treatment of dry WCCO followed by high temperature bauxite treatment yield finished oil of inferior quality. Re-refining by high temperature WCCO treatment, followed by clay treatment, filtration, and catalytic hydrogenation, and re-refining by propane treatment of dry WCCO followed by catalytic hydrogenation yield finished oil of satisfactory quality; but, compared to the process of this invention, hydrogenation pressure and temperature must be higher, hydrogenation L.H.S.V. must be lower, hydrogen consumption is at least doubled, hydrogenation catalyst life is reduced, larger hydrogenation capacity is required, and more fuel from external sources is required. In addition, little or no lube oil fractionation is carried out to separate the light ends, heavy ends, lube stock, and bright stock.
The process of this invention consists of the following steps:
1. Screen out large pieces of debris and dehydrate the oil.
2. Mix the dry oil with 1-15 (preferably 4-6) times its volume of a saturated hydrocarbon selected from the group consisting of ethane, propane, butane, pentane, hexane, and mixtures thereof (preferably propane). Keep the mix liquid under pressure at a temperature near but below its critical point. In the case of propane, we prefer temperatures of 180°-190°F. at 600-700 psig. Settle the mix, drain off the bottoms, and separate the clarified oil-solvent mix. The bottoms can be burned to supply process heat. A special scrubber must be used to remove heavy metal particulates from the combustion gases.
3. Strip the solvent from the clarified oil-solvent mix of step 2, condense it and store for reuse. Collect the stripped oil.
4. Vacuum distill the stripped oil of step 3 at a pressure no greater than 10 torr and a temperature no greater than 650°F., distilling over all but 10-15% of the charge stock. Fractionate the distillate. No maintenance or yield problems result from vacuum distilling this material. The vacuum bottoms can be burned to supply process heat. No special scrubber is needed.
5. Hydrogenate the condensed hot oil fractions over a catalyst consisting of one or more Group VI and/or VIII metal oxides or sulfides at 500°-800°F. (preferably 600°-700°F.), 500-1000 psig (preferably 600-700 psig), and L.H.S.V. = 0.5-2.0 (preferably 1.0).
6. Strip the hydrogenated oil fractions of hydrogen, reduction products, and light ends.
7. Cool and filter the oil.
Each step of the process of this invention is known, but the novel sequence of steps has not been stated or appreciated till now. The precipitative hydrocarbon step removes 70-80% of the original WCCO impurities. Impurities precipitated by the hydrocarbon solvent consist of high molecular weight additives, additive fragments, and oil oxidation products, plus high density particulates. The vacuum distillation step removes 10-15% of the original WCCO impurities and fractionates the oil. Impurities eliminated in the vacuum bottoms consist of medium molecular weight additives, additive fragments, and oil oxidation products, plus low molecular weight salts, acids, and colloidal solids. The hydrogenation step removes the last 10-15% of the original WCCO impurities by chemically transforming them into hydrocarbons having molecular weights equal to or less than oil, plus H 2 S, H 2 O, and NH 3 . Impurities removed by the hydrogenation step consist of low molecular weight additives, additive fragments, and oil oxidation products. The important features of the process of this invention are:
1. Each step removes a significant amount of impurities which are not easily removed by the previous step.
2. Each step removes a significant amount of impurities which are not easily removed by the step that follows.
3. All impurities are dependably removed.
4. Impurities are removed in the form of easily burned fuels.
5. Processing cost is the lowest of any known process.
6. Equipment maintenance costs are very low.
7. There is little oil loss and no pollution.
8. The finished oil is equal to or better than virgin lube oil in quality.
An example of the process of this invention follows:
A sample of WCCO was heated to 350°F. 2% light ends and water were removed. 500 ml of the dry WCCO were placed in a pressure vessel with 2500 ml of propane. The mix was shaken, heated to 190°F., and allowed to settle one hour. Then the propane bottoms, representing 12% by weight (10% by volume) of the dry WCCO, were drained out of the pressure vessel. The clarified propane-oil mix was decanted and depropanized, then the 450 ml of propane-treated oil was subjected to a nitrogen-vacuum distillation at 10 torr. The first 10% of distillate was considered to be heavy ends, the 10-90% cut (b.p. 490°-620°F. at 10 torr) was considered to be in the lube range, the last 10 % was left in the pot. The lube oil cut was hydrogenated in a pressure vessel under the following conditions:
oil:catalyst volume ratio=1:1
catalyst=Houdry HR-801 cobalt-molybdenum catalyst, 25% sulfided
temperature=650°F.
reaction time=1 hour
H 2 pressure=650 psig
Then it was lightly stripped to remove 1-2% light ends, reduction products and hydrogen, and filtered to remove catalyst fines. Properties of the finished lube oil are shown in Table 1.
Table 1 ______________________________________ Properties of WCCO and finished lube oil made by the process of this invention WCCO Finished lube ______________________________________ viscosity at 100°F. 319 SUS 170 SUS viscosity at 210°F. 59.6 SUS 44.6 SUS viscosity index 141 101 color, ASTM black 1.5 color after 16 hours at 210°F. black 2.0 - gravity at 60°F. 24.4°API 30.5°API (0.875 g/ml) flash (Cleveland Open Cup) 360°F. 445°F. fire (Cleveland Open Cup) -- 495°F. ash 1.81 less than 0.001% pour point -40°F. 15°F. T.A.N. (ASTM D664) 5.87 0.06 mg KOH/g Conradson carbon 5.20 less than 0.001% Cu strip corrosion -- passes, 1B (3 hr. at 210°F.) sulfur (ASTM D1552) 0.32 0.08% nitrogen 0.17 0.05% ______________________________________