EP0249748A1 - Process for the destructive hydrogenation of carbon-containing wastes in a fluidized bed - Google Patents

Abstract

1. A process for the production of hydrocarbons from carbonbearing wastes by the hydrogenating separation of the carbon-bearing wastes with hydrogen and/or hydrogen-bearing gases and/or compounds which give off hydrogen, characterised in that the hydrogenating separation operation is effected at 250 to 900 degrees C and 5 to 280 bars in a fluidised bed.

Description

The present invention relates to a process for working up waste containing carbon by hydrogenating it in the fluidized bed.

It is known in the public and in the professional world that the waste generated worldwide represents an increasingly greater burden on the environment.

Waste has been used in landfills for decades, e.g. stored in abandoned gravel pits, mine pits and elsewhere. For a long time, the chemical structure of the waste and its long-term effects on soil and groundwater have not been taken into account. More recently, certain waste has been stored in so-called special landfills. Here, efforts are made to seal the landfill from groundwater and soil.

For some time now, experts have made intensive efforts to process or process the waste, firstly to protect the environment and secondly to obtain usable products from the waste.

So in "The Oil and Gas Journal", Dec. 25, 1978, p. 80, described a pilot plant in which plastics can be converted into gases and oils by pyrolysis. In "Hydrocarbon Processing", April 1979, p. 183, an incineration plant is described in particular for special waste.

The biochemical degradation of plastics has also been investigated (see for example "European Chemical News", Sept. 10, 1979, p.28).

In Chemical Engineering, August 13, 1979, p. 41, a method is described according to which hazardous wastes are deposited in hardening materials, e.g. Cement to be poured.

An overview of the most important processes is given in "Chemical and Engineering News", Oct. 01, 1979, p. 34. Here, in particular, the gasification of biomass, namely wood waste and the like to carbon monoxide and hydrogen, is described. On page 36, left column of this document, a test program for converting shredded wood into water is also described, using hydrogen in the presence of Raney nickel as a catalyst.

In "Europa Chemie", 25, 1979, p. 417, a method is described according to which unsorted plastic waste is plasticized and pressed.

The fluidized bed combustion of waste is described in "Chemische Industrie", XXXII, April 1980, p. 248. The conversion of waste and biomass by heating with water and alkalis is described in "Chemistry International", 1980 No. 4, p. 20.

Numerous other publications have also become known.

In recent times, combustion in modern facilities in particular has been further developed and large-scale plants have been built that use this method. Although dedusting and flue gas scrubbing are integrated in such systems, pollutants escape into the atmosphere in small proportions even with careful cleaning, such as heavy metals, SO₂, NO _x and others.

Pyrolysis is now also being operated on a technical scale (see, for example, "Vereinigte Wirtschaftsdienste GmbH", 04. Oct. 1985, p.9). However, pyrolysis has the disadvantages of the predominant formation of gaseous products and a heavily contaminated coke residue.

The problem of waste processing is therefore still not satisfactorily solved according to this prior art.

A surprising, compared to the prior art much cheaper solution to this problem, especially with regard to the recovery of very high proportions of valuable products, the present invention discloses, characterized in that carbon-containing waste in the fluidized bed with hydrogen and / or hydrogen-containing gases and / or hydrogen-donating compounds are implemented.

This method enables waste from which larger inorganic constituents of glass, metals, stone materials and the like are largely removed without further processing to valuable hydrocarbons, that is, to C₁-C₄ hydrocarbon gases, to hydrocarbons boiling in the gasoline sector and to medium and Heavy oils that can be used as diesel oil and for heating purposes. It is also of particular advantage that the products used need only be comminuted a little, that the products are practically olefin-free and that hetero elements are obtained as hydrogen compounds which can be easily worked up according to the prior art.

Pre-sorted materials can also be processed according to this method, in particular in such a way that, for example, mixtures of carbon-containing wastes of synthetic origin, such as plastics, or plastic mixtures, rubber, tires, textile wastes and the like contained in household waste, are at least roughly separated from the vegetable or biomass portion and then subjected to the hydrating treatment, possibly together with industrial waste, such as paint and paint residues and organic chemicals, industrial production waste, organic-synthetic shredder waste from the automotive industry, cable waste, used tires, Sewage sludge or with waste oils u. The like. In this case, other wastes such as paper, food residues, agricultural and forestry wastes, wood, plants and the like can be largely separated off, but also to a certain extent remain in the synthetic portion.

The synthetic individual components can also be processed very well into valuable liquid products under the conditions according to the invention. For example, production-specific or waste-generator-specific waste can also be used, at least temporarily, separately from other types of waste.

For example, in the cable industry there is a large amount of cable waste, in the automotive industry there is a large amount of so-called shredder waste, in the paint industry there is a large amount of paint and varnish waste, in the carpet industry there is a large amount of carpet waste, in the rubber and the tire industry generate large amounts of elastomer waste or their further processing products, large amounts of waste are generated in the plastics industry, such as in the manufacture and processing of plastics, foams, elastomers and insulating materials, and large amounts of synthetic-organic waste are generated in the chemical industry in the production of chemicals, which cannot be listed in detail here. However, pre-sorted synthetic, organic waste can also be generated in technical waste separation plants. The list of the production-specific or waste-generator-specific wastes mentioned should not be regarded as limiting, since, according to the present invention, all synthetic organic compounds can be converted into valuable products by hydrogenation.

Most of the time, these production-specific or waste-generator-specific wastes are mixtures;
shredder waste usually consists of plastic mixtures, cable waste from mixtures of different components, textile waste from mixtures.

The same applies to other waste. According to the invention, however, uniform or very uniform waste can also be implemented very well. The waste producer or production-specific waste can be used at least temporarily, for example until a supply of such waste has been used up.

In the meantime, non-waste producer or production-specific waste can also be implemented, i.e. mixtures of several types of waste or e.g. Mixtures of synthetic-organic waste as they occur in waste separation plants.

The process is also very well suited for the joint hydrating treatment of the waste or waste mixtures mentioned with coal, coal components, such as, for example, coal oil residues, coal oils, pyrolysis oils, petroleum, petroleum residues, other petroleum components, oil shale, oil shale components, oil sands, bitumen and the like or the like Mixtures of these materials. It is generally known that in the case of the simultaneous hydrolytic cleavage of these additives, numerous catalysts are suitable.

According to the present invention, the carbon-containing wastes to be reacted with hydrogen and / or hydrogen-containing gases and / or hydrogen-releasing compounds are reacted with these gases in a fluidized bed, if appropriate in the presence of biomass or other vegetable or cellulose-containing materials, the gases being used to react with the gases Fluidized bed is at least partially generated or maintained. The gases can also contain other components, such as N₂, CO, CO₂, CH₄ or water vapor. However, Gesamt 25% by volume of hydrogen is contained in the total amount of gases. As fluidized bed reactors, both state-of-the-art reactors and further developed fluidized bed reactors can be used. The solid, carbon-containing wastes used can be comminuted to different material sizes or can also be used without comminution. In addition, a solid carrier material can be used both in a straight pass and at least partially recycled. Such materials can be, for example, inert materials, such as sand, gravel, corundum, ceramics, clay, coke or the like, and these materials can also serve as heat carriers. However, it can also be catalytically active solid materials such as, for example, Fe, Mo, Ni, Co, W and other hydrogenation-active metals and / or catalysts containing their compounds, it being possible for these to consist of individual or at least two of these components and the metals and / or the compounds of which can be applied to carriers, for example to aluminum oxide, silicon dioxide, aluminum silicates, zeolites, the above-mentioned solid additional materials and other carriers known to the person skilled in the art or from carrier mixtures. However, they can also be used without a carrier. Certain zeolites as such are also suitable.

Other suitable catalysts can be so-called disposable catalysts, such as hearth coke, Winkler gasification dusts, dusts and ashes, which are obtained in the hydrogenating gasification of coal to methane (HKV dusts), but also mixtures containing iron oxides and other iron compounds, such as red mud, Bavarian mass, Lux mass, dusts from the iron industry and others, whereby these materials can also be doped with hydrogenation-active metals and / or metal compounds, in particular with heavy metal salts, such as, for example Iron salts or salts of chromium, zinc, molybdenum, tungsten, manganese, nickel, cobalt, also with alkali, alkaline earth, etc. as well as with mixtures of these compounds. At least some of the catalysts can be pretreated sulfiding. It goes without saying that all of the support materials and catalysts mentioned can be used both individually and in mixtures.

Both solid and liquid waste and, if necessary, additional biomass or other vegetal or cellulose-containing materials can be used in the fluidized bed, the gas supply being adapted accordingly. Examples of solid waste that can be used both individually and in a mixture are:
Plastics, rubber, tires, textiles, paint and varnish residues, shredder waste, in particular from the automotive industry, cable waste, paper, solid vegetable waste, wood, vegetable and other cellulose-containing waste, other solid organic synthetic industrial waste. Solid additives to this waste can be: coal, such as brown or hard coal, peat, oil shale, bitumen, or mixtures thereof. However, other solid, carbon-containing wastes not mentioned here can also be converted into valuable products under the conditions according to the invention. Examples of liquid waste are:
Waste oils, residual oils from mineral oil and coal processing, pyrolysis oils, crude oils, oil shale and oil sand oils, liquid organic-synthetic industrial waste, bio-sludge. However, other liquid feed products or waste products not mentioned here can also be used under the conditions according to the invention implement valuable products.

The fluidized bed area can consist of liquid waste or molten solid waste, the additives mentioned, e.g. Residual oils, coal, etc. may also be included, and solid finely divided catalysts or inert solid materials or both are kept in a swirling motion within the liquid by the supplied gas.

In the case of waste materials which are infusible in the temperature range according to the invention, the fluidized bed process can also be carried out without the presence of liquid or in the presence of only a little liquid product. The conditions of the hydrogenating reaction according to the invention can be varied within wide limits depending on the starting products. The temperature is 300 to 900 ° C, preferably 350 to 800 ° C and particularly preferably 400 to 600 ° C. The pressure is 1 to 320 bar, preferably 5 to 280 bar and particularly preferably 8 to 240 bar. The ratio of hydrogen to the feed product is determined in particular by the amount of gas required for a given piece or grain size or the amount of solid and / or liquid feed product which is necessary to maintain the fluidized bed. The gas velocity can be, for example, in the case of so-called stationary fluidized beds at 0.05 to 1.5 m / sec., Preferably at 0.2 to 1 m / sec. can also lie in the case of so-called fast riser fluidized beds up to 30 m / sec. to reach. However, it must be taken into account here that the maintenance of the fluidized bed and the flow rate of the liquids used are also determined by adding other gases and adding water vapor. All hydrogen qualities can be used as hydrogenation gas, also with admixtures such as CO, CO₂, H₂S, methane, ethane, water vapor, etc.

Hydrogen qualities, such as those which arise in the gasification reactions of carbon-containing materials with water vapor, are very suitable. Such materials can be residues from the processing of mineral oils or coal, wood, peat or residues from the coal processing, for example hydrogenation. Biomass or the vegetable parts separated from household waste are also suitable.

Pure H₂ qualities such as hydrogen electrolysis are of course also very suitable.

For example, according to the invention, domestic waste can first be separated into vegetable and synthetic parts and then the vegetable part for hydrogen generation can be gasified while the synthetic part is subjected to the hydrogenating treatment. The vegetable portion can also be used for fermentation or other processing.

A solvent treatment with hydrogen-transferring solvents can also precede the hydrogenating treatment, after which a separation into dissolved and undissolved can take place and the undissolved can be fed to the fluidized bed hydrogenation reactor (s).

In this variant of the process as well, the feed product can be mixed with coal and / or coal components and / or petroleum residues and / or petroleum and others. be hydrogenated. Suitable solvents are e.g. Tetralin, anthracene oil, isopropanol, oils containing cresol, decalin, naphthalene, tetrahydrofuran, dioxane, but also, for example, petroleum-derived hydrocarbons and oils and oxygen-containing hydrocarbons and oils. Finally, water or steam can also be added.

According to the method mentioned, waste mixtures can also be processed in a hydrogenating manner in such a way that mixtures of vegetable and synthetic waste, if appropriate with the addition of biomass, are reacted in various stages under conditions in which, on the one hand, the hydrolytic and / or hydrogenating conversion of vegetable or Paper and biomass and on the other hand the hydrogenation of the synthetic organic waste takes place.

In the 1st stage, for example, a hydrogenating treatment can optionally be carried out in the presence of hydrogenation catalysts and a pressure of 1 bar to 150 bar, preferably 25-60 bar, preferably in the presence of water and other protic solvents such as alcohols.

The oils obtained predominantly from the vegetable portion can then be separated off by solvent extraction, after which the portion which is not hydrolyzed can be hydrolyzed in the fluidized bed in the second stage under conditions already described.

The stepwise processing can also be carried out in such a way that vegetable parts or paper parts or biomass are hydrolytically split in the first step, for example in the presence of alkalis or acids, this reaction possibly taking place in the presence of CO and preferably in the presence of water and / or other protic solvents such as alcohols and in the second stage the synthetic or predominantly synthetic portion in the fluidized bed is reacted in a hydrogenating manner.

Alternatively, the waste and / or the biomass can be separated beforehand into a vegetable portion and a synthetic portion and processed separately under the conditions described.

In these cases too, it is possible to work both with and without catalysts. If necessary. can be dried before the 2nd stage.

According to the invention, the waste to be hydrogenated and / or the biomass can also be used in the presence of hydrogen or gases containing it and / or in the presence of hydrogen-transferring compounds, in particular so-called hydrogen donor solvents, but also in the presence of inert gases, that is to say thermally in mixing devices. esp pretreat especially in extruders and mixing / kneading devices.

Numerous other mixing devices such as, for example, kneading disc screw presses, kneaders, hollow screw heat exchangers, screw kneaders, kneading extruders, stirring apparatuses, continuous mixers, reaction mixers, kneaders, grinding devices or mills such as bead, hammer or vibrating mills are suitable for the pretreatment according to the invention .

The method according to the invention makes it possible to process even little or no pre-separated waste mixtures. For apparatus reasons, however, it is desirable to separate inorganic materials such as stones, metals, glass and the like beforehand, at least rough materials. Pre-separation into, for example, predominantly vegetable or cellulose-containing and predominantly synthetic materials can also take place, the vegetable part being able to be processed separately, for example in a fermentation.

The previous disadvantages of the prior art are overcome in an outstanding manner in particular that, despite the use of completely inconsistent waste mixtures, valuable hydrocarbon oils can be obtained in high yields and the hetero-elements present in the waste, such as oxygen, sulfur, nitrogen, halogens, are converted into hydrocarbon compounds which can be further treated in a known manner according to the prior art.

This applies in particular to waste containing chlorine, bromine or fluorine. The problems of waste mixture disposal, in particular toxic and halogenated waste, which have not yet been mastered, are therefore solved without risk according to the invention.

Solvents containing polychlorobiphenyls, PVC, fluoropolymers or halogens may be mentioned here by way of example.

According to the invention, the waste materials can also be used for petroleum, petroleum constituents and secondary products, coal, coal constituents and secondary products, asphalts, bitumen, oils from pyrolysis e.g. from coking or waste pyrolysis, oil sand products, oil shale products, heavy residual oils and the like are added and processed together.

Oils and residues originating from the plant itself can also be used according to the invention.

According to the invention, metal-containing wastes can be processed in a particularly advantageous manner, since the metals are obtained in the form of ashes after the hydrogenation and can then be subjected to metal processing.

The reaction zone can consist of one or more reactors connected in series or in parallel. The liquid hydrocarbons obtained can be processed further in accordance with the prior art, for example by means of further hydrogenating cracking stages or refining stages and separation by distillation. The uncondensed gases are scrubbed by H₂S, NH₃, HCl, possibly also CO and CO₂.

The hydrogen in the resulting gas can be returned to the hydrogenation reactor (s) as hydrogenation gas. Processing of the lower hydrocarbons contained in the gaseous products, for example by steam reforming, is also possible, with additional hydrogen being obtained.

The liquid products can be fed to a refining stage leads, which generally works hydrogenating. Small amounts of compounds containing heteroatoms which are still present can be worked up completely by hydrogenation, so that the products are then practically free of sulfur, nitrogen and halogen. Higher-boiling fractions can be fed to at least one cracking plant, in particular a hydrocracking plant. If necessary, certain portions of the processing can be returned to the waste hydrogenation or before the waste hydrogenation.

The process according to the invention can also be combined with other waste hydrogenation processes, such as, for example, a bottom phase hydrogenation.

Examples Example 1:

A waste mixture of the green bin, consisting of foils, hard plastics, textile and paper parts, which had been obtained after prior separation of the reusable components such as metals, glass and paper, was in the fluidized bed (quartz sand) at 470 ° C and 60 bar. implemented with hydrogen. A gas phase (9% by weight), 75% liquid products in the boiling range up to 390 ° C. and 16% residue (inert materials, carbon black and high boilers) were obtained as products. In addition to C₁-C₄ hydrocarbons, the gas phase contained 2% CO and CO₂.

Similar results were obtained using hearth furnace coke as the carrier material instead of quartz sand.

Example 2:

Example 1 was repeated, calcium oxide being added to the feed. With the product composition unchanged within the scope of the analysis accuracy, a HCl-free gas was obtained received phase. The HCl released from the PVC components was thus almost completely bound.

Example 3:

A mixture of synthetic waste, which consisted of daily samples from several waste separation plants, was reacted with hydrogen at 480 ° C and 100 bar in the fluidized bed (cobalt / molybdenum catalyst on Al₂O₃) without further purification. The hydrogenation was practically quantitative, but a higher gas content was obtained compared to Example 1, which is due to the higher paper and biomass content. A product was obtained which consisted of 17% gas phase, 70% liquid product in the boiling range up to 390 ° C. and 13% residue (carbon black, inert materials).

Example 4:

"Light goods" from shredder plants, which mainly contained plastics, rubber and cushioning materials, were implemented in a fluidized bed of quartz sand. The reaction took place at 460 ° C and 30 bar.

A product was obtained which contained 64% hydrocarbons in the boiling range up to 390 ° C. the gas phase, which was 12% of the total product, contained 3.5% CO / CO₂. The residue consisted essentially of inert materials such as metals, fillers, etc. and carbon black.

Example 5:

A plastic-containing waste mixture, which consisted of 30% cable sheathing, 40% light material from shredder systems and 30% old tires, was converted to aluminum oxide doped with molybdenum oxide. After hydrogenation at 490 ° C. and 120 bar, 80% by weight of liquid products up to 390 ° C. boiling ends were obtained, which contained only small amounts of olefinic hydrocarbons. the gas phase, which was 6% by weight, contained essentially saturated C₁-C₄ hydrocarbons.

Example 6:

Synthetic-organic waste components including PVC from a daily sample from a waste separation plant were brought into the fluidized bed reactor together with residues from mineral oil processing. The plastic content in use was 60% by weight. The fluidized bed consisted of aluminum silicate impregnated with iron compounds.

After reaction at 470 ° C. and 200 bar, 84% by weight of oil in the boiling range up to 390 ° C. with a high aromatic content and 11% by weight of high-boiling products and residues were obtained. The reaction gas (5% by weight) contained only traces of CO and CO₂ and the amounts of HCl corresponding to the PVC used.

When the experiment was repeated and calcium oxide was added, no HCl was found in the exhaust gas.

Example 7:

A mixture of PVC-containing plastic waste from a waste sorting plant was introduced into the fluidized bed reactor together with chlorine-contaminated oils and organic chemical residues which contained 1% by weight of chlorine. The plastic content was 60% by weight. On aluminum silicates containing nickel / molybdenum, this mixture was reacted with hydrogen at 480 ° C and 50 bar.

In addition to the gas phase (9% by weight) and 6% higher-boiling products, an oil in the boiling range up to 390 ° C was obtained as the main fraction in 85% yield. The chlorine content of this fraction was 3800 ppm.

By hydrogenating the refining of these oil fractions at 50 bar and 280 ° C in a fixed bed reactor, a product was obtained in which chlorine was no longer detectable.

Similar results were obtained with undoped hearth coke as a catalyst.

Example 8:

A mixture of tire waste, paint residue and wood waste was implemented without a carrier at 490 ° C and 120 bar. As a product 54 wt.% To 390 ° C boiling oils, 25 wt.% Gases including small amounts of CO and CO₂ and 21 wt.% Solids (metal residues, soot, pigment components) were obtained.

Example 9:

A mixture of shredded waste cables, old tires, wood and coal particles was implemented in the presence of an oven doped with FeSO₄ as a catalyst at 460 ° C and 150 bar. The product obtained was 34% by weight of oils which boiled at up to 390 ° C., 30% by weight of gases and 36% by weight of solids (in particular cable metal residues and carbon black).

Claims (10)

1. A process for working up carbon-containing waste, characterized in that the carbon-containing waste is reacted with hydrogen and / or hydrogen-containing gases and / or hydrogen-donating compounds in the fluidized bed. 2. A process for the processing of carbon-containing wastes, characterized in that mixtures of carbon-containing wastes are reacted with hydrogen and / or water-containing gases and / or hydrogen-donating compounds in the fluidized bed. 3. Process according to claims 1 and 2, characterized in that one works at a temperature of 250 to 900 ° C, preferably at 350 to 800 ° C and particularly preferably at 400 to 600 ° C. 4. Process according to claims 1 to 3, characterized in that one works at a pressure of 1 to 320 bar, preferably at 5 to 280 bar and particularly preferably at 8 to 240 bar. 5. The method according to claims 1 to 4, characterized in that additionally biomass and / or other vegetable and / or cellulose-containing materials are used. 6. The method according to claims 1 to 5, characterized in that in the presence of (one) additional (s) solids (s) in the fluidized bed reacting which are inert and / or catalytically hydrogenation-active. 7. Process according to claims 1 to 6, characterized in that one works in the presence of so-called disposable catalysts. 8. Process according to claims 1 to 7, characterized in that one works in the presence of catalysts which contain hydrogenation-active metals, in particular Fe, Mo, W, Ni, Co. 9. The method according to claims 1 to 8, characterized in that the waste to be hydrogenated in a mixture with petroleum and / or petroleum constituents, in particular petroleum residues and / or coal and / or coal constituents and / or oil shale and / or oil shale components and / or oil sand extracts and / or bitumen and / or asphalt and asphalt thenes are implemented. 10.The method according to claims 1 to 9, characterized in that the hydrogen content in the feed gases in the fluidized bed is ≧ 25% by volume.