EP0228651B1 - Process for obtaining high-grade lubricants from spent oils - Google Patents

Abstract

Spent oils or mixtures containing spent oil are treated by catalytic hydrogenation at elevated pressure and elevated temperature with a 20 - 70 % reduction of the fraction boiling at 350 DEG C.

Description

The invention relates to a process for the catalytic hydrogenating treatment of waste oils or mixtures containing waste oil at elevated pressure and temperature while reducing the portion boiling> 350 ° C. by 20-70%.

The term "waste oils" includes all waste oils such as used spindle oils, machine oils, lubricants for motors and gears, cylinder oils, metalworking oils, hydraulic oils, industrial waste oils, etc.

The waste oils are used oils that can no longer be used as such. Waste oils mainly consist of a base oil based on mineral oil or synthetic oil, but some contain considerable amount of foreign matter, e.g. Water, solvents, fuels, asphalt-like substances, acids, resins, ashes and additives, such as antioxidants, anti-corrosion agents, wetting agents, dispersants, anti-foaming agents, viscosity index improvers, etc. The additives can contain halogens, sulfur and nitrogen compounds, and numerous other partially toxic components. Common synthetic lubricating oils are, for example, polyether oils (e.g. polyethylene glycol, polypropylene glycol or mixed polyolefin glycols), ester oils, silicone oils, oils from chlorinated or fluorinated hydrocarbons, etc.

It is generally known that it is of considerable economic interest to obtain reusable products from the large amounts of waste oil produced.

The reprocessing of used oils is referred to as secondary refining. The methods corresponding to the state of the art have met with considerable public criticism in particular recently, since used oils are generally not stored and stored separately according to their origin, but mostly from mixtures of e.g. Motor oils based on mineral oils, machine oils, synthetic oils, transformer oils etc. consist. Mixtures of the latter oils can lead to the formation of highly toxic dioxins during combustion.

A known second refining process is, for example, the sulfuric acid bleaching earth hot contact process, in which after atmospheric drying to 0.12% water content, about 11-13% by weight sulfuric acid is added to the waste oil and passed into settling tanks. After 24-48 hours, additional treatment is carried out with bleaching earth (waste oil recycling, K. Müller, Erich Schmidt Verlag GmbH, Berlin, 1982, p. 89).

The hydrogenating refining of waste oils is also known. For example, in the Phillips Company's PROP process, after pretreatment with an aqueous diammonium phosphate solution, there is a refining hydrogenation over nickel-molybdenum catalysts (US Pat. No. 3,879,282, US Pat. No. 3,930,988, US Pat. No. 4,151,072: Hydrocarbon Processing, Sept. 1979, p. 149).

The refining hydrogenation according to this process takes place after several pretreatment steps at 200-430 ° C., preferably at 360 ° C. and a pressure of 10.2-206.7 bar, preferably 50.3 bar (US Pat. No. 4,151,072, FIG. 1 ).

Although the PROP process also at least partially degrades polychlorobiphenyls (Hydrocarbon Processing, Sept. 1979, p. 152, right column, lines 43-51), chlorinated solvents and cleaning fluids, metalworking oils, other working fluids as well as insulating and transformer oils undesirable as feedstocks in the PROP process. Suitable products for the PROP process are therefore essentially used engine oils.

Another process with a hydrating stage is the so-called KTI process (Kinetics Technology International). According to this process, after the removal of volatile components such as gasoline, solvents etc., vacuum distillation is carried out at 26 mbar and 270 ° C. In the next stage, high-vacuum distillation takes place at 310 ° C and 2.6 mbar, which is designed as thin-film evaporation. The product is then subjected to hydrogenating refining at 50 bar and 300-350 ° C.

The process stages make it clear to the person skilled in the art that this process is associated with a very high technical outlay, so that the economic viability is questioned (see K. Müller, "Waste Oil Recycling", Erich Schmidt Verlag, Berlin, 1982, pp. 128-135) , in particular p. 135, 2nd paragraph).

There is therefore still no technical process available that enables the processing of waste oil mixtures, with the result that valuable products, in particular high-quality hydrocarbon lubricants with a high viscosity index and products that can be used as feedstocks for the ethylene plant, are produced with simultaneous, complete degradation of the heterocouples , in particular the halogens, oxygen, sulfur and nitrogen, which can be operated under economically justifiable conditions.

A solution to this problem is disclosed by the present invention, which permits the production of high-quality lubricants with a high viscosity index and the production of valuable feedstock for ethylene plants by catalytic hydrogenation treatment of solids, if applicable, and other dissolved substances and / or emulsified additives and water and, if necessary, chemically and / or physically pretreated waste oils or mixtures containing waste oils with hydrogen and / or hydrogen-containing gases and / or hydrogen-transferring solvents, characterized in that the hydrogenating treatment is carried out in the presence of a ( of) commercial hydrocracking catalyst (s) at temperatures of 350-480 ° C, pressures of 20-400 bar, an LHSV of 2-20 1 / 1`h, and that the portion with boiling points> 350 ° C 20-70% reduced.

• die Entfernung leicht siedender Anteile durch Abdestillieren;
• die Sedimentation von Feststoffen;
• die Abscheidung von Wasser;
• Trocknung;
• die Verdünnung mit Verdünnungsmitteln und anschließende Abtrennung von ausgeschiedenem Wasser oder ausgefällten Feststoffen;
• Filtrieren;
• Zentrifugieren;
• Behandeln mit Adsorbentien wie beispielsweise Bleicherde, Perlite, Zellulosematerialen, Adsorptionskohle, u.a.;
• Dampfbehandlung;
• Extraktion (Lösungsmittelraffination);
• überkritische Extraktion;
• Destillation im Vakuum, ggfs. Dünnschichtverdampfung.
• chemische Vorbehandlungen, wie beispielsweise die Behandlung mit Diammonphosphatlösung;
• die hydrierende raffinierende Vorbehandlung;
• Behandlung mit Schwefelsäure;
• Behandlung mit Laugen oder Kalk, u.a.

Depending on the type and amount of impurities or admixtures, the waste oils or their mixtures can be pretreated in accordance with the prior art.
Examples include:

• the removal of low-boiling fractions by distillation;
• sedimentation of solids;
• the separation of water;
• Drying;
• dilution with diluents and subsequent separation of water or precipitated solids;
• Filter;
• Centrifuge;
• Treatment with adsorbents such as bleaching earth, perlite, cellulose materials, adsorption carbon, among others;
• Steam treatment;
• Extraction (solvent refining);
• supercritical extraction;
• Distillation in a vacuum, possibly thin film evaporation.
• chemical pretreatments, such as treatment with diammon phosphate solution;
• the hydrogenating refining pretreatment;
• Treatment with sulfuric acid;
• Treatment with lye or lime, among others

Although it is known to obtain lubricants with a high viscosity index by hydrocracking feedstocks with a high proportion of straight-chain paraffins (see, for example: VI Karzhev, EM Nikonorov, EI Silchenko, AI Dintses, TM Komissarova, EP Detusbeva, SZ Levinson, 9. Welterdölkongreß, Applied Science Publishers, 1975, Vol. 5, p. 191), whereby the straight-chain paraffins are partly split and isomerized, so that after dewaxing a lubricant is formed which consists practically entirely of branched paraffins, it was surprising that also when using used lubricant that contains almost no straight-chain paraffins, also by the method according to the invention
Lubricants with a high viscosity index can be obtained. A further advantageous effect of the process according to the invention is the degradation of the synthetic lubricants contained in waste oil, such as the ester lubricants, the polyalkylene glycols, silicone lubricants, lubricants containing sulfur and others. In this way, a particularly valuable lubricating oil product is obtained which consists practically entirely of hydrocarbons and, in addition to being used as a lubricant, is also outstandingly suitable for use as an ethylene feed, with over 30% by weight of ethylene being obtainable. In addition, the hydrocarbons obtained in the gasoline and medium oil boiling range can also be used as ethylene feed.

According to the invention, both zeolitic and amorphous catalysts, such as are commercially available, can be used as hydrocracking catalysts. The active hydrocracking components can be, for example, Ni / Mo, Ni / W, Co / Mo, Co / W or mixtures thereof, but also other metals or metal compounds, for example from sub-group VIII to VIII of the periodic table. Accordingly, in the method according to the invention, for example, all are state of the art suitable hydrocracking catalysts.

According to the invention, however, amorphous hydrocracking catalysts are preferred, which according to the prior art, for example, aluminum silicates, SiO₂, Al₂O₃, etc. May contain oxides as a base.

It was surprisingly found that amorphous and crystalline, zeolitic catalysts yield comparable results in terms of yield and viscosity index, but that in the presence of amorphous catalysts there is practically no increase in the pour point, whereas in the presence of crystalline, zeolitic catalysts there is a sharp increase in the pour point are observed, so that when the products are used as lubricating oil in the latter case dewaxing is required.
If the products according to the invention are used as ethylene feed, the pour point has only a minor influence.

Commercially available refining catalysts can optionally also be used according to the invention under more stringent conditions than gap catalysts.

In general, the catalysts are used according to the invention as fixed bed catalysts, but the results according to the invention are also obtained when using the fluidized bed or fluidized bed process.
Methods can also be used in which the catalyst is in suspension.

The feed product to be treated according to the invention is reacted with hydrogen, hydrogen-containing gases, which may additionally contain, for example, N₂, CO₂, hydrocarbons and other admixtures or mixed with hydrogen-transferring solvents at temperatures from 350 to 480 ° C., pressures from 20 to 400 bar and an LHSV of 2 to 20 l / h`l, the conditions being set depending on the feed product so that the proportion in the feed oil with a boiling point> 350 ° C. is reduced by 20 to 70%. The process is preferably carried out at a temperature of 400 to 460 ° C, a pressure of 100 to 350 bar and an LHSV of 4 - 12 l / h`l and the proportion in the feed oil with a boiling point> 350 ° C is reduced by 30 - 60%.

The hydrogenation temperature can also be a temperature profile e.g. be a sawtooth profile.

The splitting hydrogenating treatment is preferred, in particular when using crystalline zeolite catalysts, before a refining step. The catalyst volume of the refining stage usually corresponds approximately to that of the hydrocracking stage. However, depending on the composition of the feed oil, changes in the volume ratios are possible within wide limits, for example from 5: 1 to 1: 5. Commercial products can be used as refining catalysts. Furthermore, as already explained above, a stage for removing metals can be installed.

According to the invention, it is also possible to use a catalyst which has both refining and cleavage properties, preferably two separate catalyst beds which are operated under different conditions, in particular at a higher temperature in the cracking stage.

Surprisingly, it was found that the process according to the invention uses waste oils Lubricating oils are obtained which are free from oxygen, halogen, nitrogen, sulfur and metals and have viscosity index values (VI) of 110 to 130, good to high yields being obtained depending on the viscosity index.
The used waste oils can also contain, for example, synthetic oils based on polyether, polyglycol, polyester, polychlorobiphenyls, etc. or small proportions of oils with a viscosity index <90, such as transformer oils. If necessary. can also be mixed with crude oil, residual oil from mineral or coal origins and similar oils, such as from oil shale, oil sands and the like, with dewaxing being added if necessary.

Using the process according to the invention, about 25-75% HVI oils (HVI = high viscosity index) can be obtained from the oils mentioned, in addition to lower-boiling products, especially those from the middle oil and petrol sectors.

The conditions according to the invention additionally lead to the almost complete degradation of the compounds with hetero elements in the feed product. For example, chlorine-containing compounds are no longer detectable in the lubricant product, and sulfur and nitrogen compounds, which for example derive from the added dissolved additives, are almost completely broken down.

The products obtained under the conditions according to the invention are also outstandingly suitable as feeds for use in ethylene plants. Here, as in the case of the production of lubricants with a high viscosity index, it should be noted that, depending on the used oil or used oil mixture, temperature, pressure and residence time have to be adjusted accordingly.

The invention is illustrated by the following examples.

Example 1

Technical, pre-cleaned waste oil was subjected to a vacuum distillation under the usual technical conditions. The boiling cut with the ASTM D 1160 boiling analysis:

10% to 392 ° C
50% to 462 ° C
90% to 471 ° C
Viscosity index 102

which contained 4.5% by weight of a synthetic ester oil was hydrogenated at an LHSV of 8 l / lh, a pressure of 220 bar at 410 ° C. in the presence of an amorphous commercial hydrocracking catalyst. 30% of the> 350 ° C boiling portion was broken down.
60%, based on the starting product, of lubricating oil free of ester oil and having a viscosity index of 115 and a boiling range> 400 ° C. were obtained. In addition, lower-boiling products were obtained, especially in the middle oil and petrol sector.

Example 2

The experiment according to Example 1 was repeated, but the process was carried out at 440 ° C. and the portion boiling> 350 ° C. was reduced to 60%.
30% of an ester oil-free lubricating oil were obtained with a viscosity index of 125 and a boiling range> 400 ° C. Similar results were obtained with different refining upstream.

Example 3

The experiments according to Examples 1 and 2 were repeated, but in the presence of a crystalline, zeolitic, commercially available hydrocracking catalyst. Almost the same results were obtained as in Examples 1 and 2.

Example 4

The sections> 400 ° C. obtained according to Examples 1 and 2 were examined with regard to their pour point. The following results were obtained:

Example 5

Pre-cleaned and distilled waste oil with a proportion of 3% by weight of polyalkylene glycol lubricating oil was reacted with a 20% degradation over a boiling portion> 350 ° C. over an amorphous catalyst.
73% of a> 400 ° C. boiling polyalkylene glycol-free lubricating oil with a viscosity index of 110 were obtained.

Example 6

Pre-cleaned and distilled waste oil with a proportion of 7% by weight of synthetic lubricants containing polar groups was reacted with a 70% degradation of the> 350 ° C. boiling proportion over an amorphous catalyst. 21% of a> 400 ° C. boiling lubricating oil which was free of polar groups and had a viscosity index of 129 was obtained

Example 7

Example 5 was repeated, the feed oil containing 6000 ppm polychlorobiphenyl (PCB).
<1 ppm PCB was found in the product.

Similar good results were also obtained with different temperatures, pressures and residence times depending on the waste oil.

According to the invention, similarly good results are also obtained if the used waste oil is pre-cleaned differently than vacuum distillation.

The pre-cleaning should be selected so that the catalyst is not damaged or only slightly damaged or is inactivated little by impurities. Suitable measures must therefore be taken depending on the used oil from the state of the art.

Claims (2)

1. Process for producing high-quality lubricants from waste oils by catalytic hydrogenation of waste oils or mixtures thereof with hydrogen and/or hydrogen-containing gases and/or hydrogen-transferring solvents, optionally freed from solid material, other dissolved and/or emulsified additives and water and,optionally, pretreated chemically and/or physically, characterized by carrying out the hydrogenating treatment in the presence of one or more commercial hydrocracking catalyst(s) at temperatures of 350-480 °C, pressures of 20-400 bar and a LHSV of 2-20 1/1 x h and reducing that portion having a boiling point of greater than 350 °C by 20-70 %.
2. Process according to claim 1 characterized by using as a hydrocracking catalyst an amorphous catalyst and carrying out the hydrogenating treatment at a temperature of 400-460 °C, a pressure of 100-350 bar and a LHSV of 4-12 1/1 x h and reducing that portion having a boiling point of greater than 350°C.