DE2424605A1 - Thermal degradation of org polymers - with heavy metal oxide and org peroxide as catalyst system - Google Patents

Abstract

Thermal degradation of high mol wt org. matl esp. thermoplastics, oils and fats, is effected by (a) heating the org. matl to 750-850 degrees C under an inert atmos in the presence of an effective amt of a catalyst system consisting of (I) 1-99 pts wt oxide or oxide-forming cpd of a heavy metal, esp. a mixt of Ba, Cr, and Cu oxides, and (II) 99-1 pts wt cpd. of formula: (where R is hydrocarbyl; and R1 is H or hydrocarbyl). Degradation to useful prods is effected without contamination of the environment.

Description

Pyrolytic treatment process for organic waste The The invention relates to a method for the chemical decomposition of high molecular weight organic Material, in particular of thermoplastic polymers, oils and fats and their Compounds, to low molecular weight hydrocarbon compounds with 1 to 12 carbon atoms.

Developing an effective waste disposal process society is a global and pressing problem. Of the many factors which contribute to the urgency of perfecting such a procedure is Perhaps the most complicated is the visualization that the conventional methods of elimination because of their considerable pollution of the environment for the wider public Use are no longer acceptable.

Nowhere is this problem of waste disposal as difficult as with materials such as plastics, rubber, oils, greases and the like. These high molecular weight Organic materials do not decompose easily when exposed to the elements will. For practical purposes they always remain in their existing physical form State. While it would seem that this trait is a circular process make these materials possible, this cannot be done commercially. Impurities added during manufacture and / or use (e.g. Extenders and dyes in the case of plastics, and metal splinters, dirt and / or water in the case of oils and fats), and sometimes the irreversible nature of the manufacturing process itself (as with car tires) speak against a circular process of these products. In this way, large quantities of what is actually- belongs to permanent waste.

It is an object of the present invention to provide an elimination process for solid and liquid organic waste products to create a minimum Environmental pollution brings with it the solid and liquid organic waste and scrap can be converted into end products that may be commercial are utilizable, and which are the thermal decomposition of high molecular organic Material in predominantly short-chain hydrocarbon gases and volatilizing Liquids made possible.

The solution to the problem is to be seen in the fact that the organic material is heated to temperatures between 750 and 850 ° C in a gas atmosphere inert to the decomposition reaction and with the help of an effective amount of a two-component pyrolysis catalyst system, which is essentially composed of: a) 1 part to 99 parts of a first pyrolysis catalyst from a group of heavy metal oxides, oxide-generating compounds of heavy metals and mixtures thereof, and b) 99 parts to 1 part of a second pyrolysis catalyst from the group of compounds with the following structural formula: where R is a hydrocarbyl and R 'is hydrogen or a hydrocarbyl.

According to the invention, those to be decomposed are solid and liquid organic waste in a two-stage pyrolytic sequence if present a two-component catalyst system heated to temperatures of 750-8500C. The two catalyst components are the waste materials before or at the beginning of the added to the first stage of the series. As each catalyst component with the other is very reactive, it is essential that the catalysts are added separately, the second not being added until the first is completely in the mass of the organic material to be decomposed is distributed.

Pyrolytic heating is started after both catalysts are thoroughly mixed with the bulk of the organic waste, to form an im essential liquid state (i.e. as a melt or suspension). Another The crucial importance of this invention is that the second pyrolysis stage is carried out under an atmosphere which is opposite to the reaction conditions is inert.

The invention is described below on the basis of several exemplary embodiments described in addition.

By and large, the process of the present invention can be viewed as an improvement in pyrolysis technology, which is decomposition distillation or the "cracking" of high molecular weight organic molecules by heating under Absence of oxygen or oxidizing agents. The process according to the invention differs from pyrolysis in that an inert carrier gas is in contact is used with a particularly mixed catalyst system.

The material to be decomposed can be any high molecular weight organic material be. While the invention is intended for use with waste or scrap, it should also be taken into account that the process can also be carried out with organic material, which is not waste or scrap can be used.

High molecular weight material is any material or compound of one or more materials to be understood physically in each state from non-volatile liquid to solid and their molecular structure can be described as a chain of repeating sub-molecular groups, in which carbon is the predominant chain atom. In that definition are Materials such as natural and synthetic resin products, further than either thermoplastic or thermosetting polymeric structures can be designated, such as polyolefin and phenol formaldehyde, as well as natural and synthetic rubber, vulcanized or not, protein and cellulose, which could be included in general waste, including petrochemical products such as greases, lubricants, motor and heavy fuel oils.

According to the invention, that to be decomposed becomes organic high molecular weight Material heated in the presence of a catalyst system consisting of two different Pyrolysis catalysts are made, each of which is perfectly uniform throughout Mass of organic material was distributed.

If the organic material is predominantly liquid or semi-solid, the uniform distribution can be achieved by simply adding. if However, if the material to be decomposed is solid, it must be mechanically and process process adapted particle size are comminuted. The smaller the Particle size the better, as this is the effective surface for the destruction process increased and so there is no other limitation than that of practical considerations certain small particle size. Such considerations will also be the greatest effective Determine particle size. In other words, the particle size should be such that that this easily through the inlet opening of a continuous reaction vessel without bridging the opening. Different sizes of reaction equipment allow the inclusion of larger sized parts of solid materials.

A first essential part of the two-component catalyst system is a metal oxide catalyst from the group of heavy metal oxides, which generate oxide Compounds of heavy metals and mixtures thereof. Metals - for heavy metal oxides, which are intended for use in the method according to the present invention, are barium, chromium, copper, lead, zinc, bismuth, nickel and the like. links of these metals which, when heated, produce oxides, e.g. carbonate or carboxylate or similar, can also be used. Of course you can too Mixtures of the oxides of two or more metals and mixtures of the oxide with Carbonate or other compounds are used. One in the process of this Invention of particularly successfully applied metal oxide catalyst is the mixture of barium, chromium and copper oxides, known to those skilled in the art as "copper-chromium iron ore".

The amount of effective metal oxide catalyst to use will vary in a wide range according to considerations with which a person skilled in the art is well acquainted is. For example, the desired appearance of the end product, the type of product to be decomposed Material and the type and amount of the second catalyst employed will each for itself and in connection with each other an influence on the necessary amount of Have metal oxide catalyst.

Generally, however, amounts ranging from about 0.05 up to 5 parts by weight of the total mixture found effective. If metal oxide mixtures, as "copper-chromium iron ore" are used, the lowest limit thereof is applied. For simple metal oxides, around 2 to 5 parts are recommended. Brought about five parts no additional effect, but a certain frictional effect and splintering could occur of the metal occur on the surface of the reaction vessel.

The second pyrolysis catalyst used as a catalyst component in the process of the present invention is selected from the group of compounds having the following structural formula where R is a hydrocarbyl and R 'is hydrogen or a hydrocarbyl. The main classes of compounds having the above structural formula are peracids, peresters, hydroperoxides, dialkyl peroxides, diacyl peroxides and ketone peroxides, hereinafter referred to simply as "peroxide compounds" or "peroxides".

Typical types of the different classes of peroxide used for the The following are suitable for use: peresters hydroperoxides t-butyl perbenzoate t-butyl hydroperoxide t-butyl peracetate n-propyl hydroperoxide sec-butyl perbenzoate sec-amyl hydroperoxide sec-butyl perpropionate sec-hexyl hydroperoxide isopropyl perbutyrate n-octyl hydroperoxide bis (4-butylcyclohexyl) peroxydicarbonate dialkyl peroxides dicyclohexyl Peroxydicarbonate di- (n-butyl) peroxide t-butyl perpivolate di- (t-butyl) peroxide t-butyl Peroctoate di <t-amyl) peroxide t-butyl perisobutyrate n-butyl-t-butyl peroxide t-butyl Peroxy 3,5,5, isopropyl t-butyl peroxide, trimethylhexanoate n-butyl 4,4, diacyl peroxide -Bis (t-butyl peroxy) valerate t-butyl perneodecanoate dibenzoyl peroxide t-butyl Percrotonate Deconoyl Peroxide Perlargonoyl Peroxide Peracids Dicumyl Peroxide Dipropionyl Peroxide Per-Acetic Acid Mixed Di (Cg-Cl5 Acyl) Perpropionic Acid Peroxides Perbenzoic Acid Per-t-Butyric Acid Ketone Peroxides Perstearic Acid Tearic Acid Methyl Ethyl Ketone Peroxide the preferred classes that fit the above formula are the ketone peroxides, peresters and alkyl hydroperoxides, and the preferred individual types are water soluble Ketone peroxides and t-butyl hydroperoxides.

The catalytically effective amount of peroxide catalysts will vary his and of the particularly used compounds, the type and amount of the associated Metalloyide catalyst material, the type and molecular weight of the one to be decomposed Material and the desired appearance of the final product depend. Usually takes the effectiveness increases with the increasing amount of the added catalyst, but decreases at a certain maximum point the effectiveness does not change significantly in any direction.

This means that the catalytic effectiveness of the peroxide has a function of the "minimum active oxygen content" of the peroxide compound employed. For example, while using about 0.66 parts by weight of an organic peroxide a minimum active oxygen content of 0.88 can be effective in one operation up to 10 parts by weight might be required if the peroxide or the peroxide mixture have a low minimum active oxygen content. It has been found that the ratio of the peroxide compound is below 0.5 part Effectiveness endangered. In the same way an addition of more than 10 parts is made mean essentially no increase in catalytic efficiency.

The ratio of the two pyrolysis catalysts that are used can also vary over a wide range. As well as the amount of each used individual catalyst, will also have the catalyst ratio, which is the largest Effectiveness achieved, be different and from such factors such as the type and molecular weight of the organic material to be decomposed, the parameters of the physical process itself and the desired end product depend on the decomposition process. Usually the ratio of a catalyst is on the other hand 1: 3 to 3: 1.

Initial experiments should be undertaken with a catalyst composition of one part metal oxide and two parts peroxide compound. Another help for choosing the starting ratio is the following table: (which is not shown as an instruction for the most effective ratio, but rather as a suitable starting point.) Peroxide content / 100 parts waste z 0.16 0.5 1 2 5 10 15 0.08 XX, X H 'e 0.5 XXX IW1 x XX a to 1.5 XXXX o I- (3 xxxx H a ,; H 5 XXX O O It is of crucial importance for the process according to the present invention that the two components of the catalyst system are added separately to the organic material. Mixing the catalyst components beforehand results in a very rapid, potentially fatal, exothermic reaction. Only when these are attached separately will the satisfactory result of the present invention be achieved. The order in which the two catalyst components are added is not important, provided that the first added catalyst is thoroughly mixed before the second is added.

The catalyst mixture should proceed in such a way that the Time when the latter of the two catalysts is thoroughly with the one to be decomposed Organic material has been mixed to form the mixture of the two catalysts with the organic material in a molten or liquid state.

For example, where the organic material is largely solid can be achieved by means of a heated screw conveyor. To get the best results achieve, the temperature in such zones should not exceed 400-500 C and if the material to be decomposed is mainly made of cellulose (e.g. paper or wood) exists, the temperature should be kept between 325-3750 C to prevent premature Prevent charring.

After the two components of the catalyst system in the organic Material has been thoroughly mixed and the mixture obtained in a convenient way molten or liquid state should be in a zone where the actual thermochemical decomposition takes place in an inert gas atmosphere, another Heating take place. This "second heating zone" can be a separate screw conveyor or be a separate part of this conveyor. Preferably the pyrolysis reaction takes place under the continuous use of the screw conveyor.

It is advantageous to use a dry nitrogen gas as the inert atmosphere to use, however, any gas that opposes that at the conditions used is inert to the reaction process, such as carbon dioxide, hydrogen, natural gas or similar, be used. Even the surrounding air can be related to the Zerwelche a higher oxygen content need to be used. Passing the inert gas by the system at a slightly above atmospheric pressure serves the additional successful purpose that the excreted gaseous products from the reaction chamber getting cleaned.

The gas should be added at a rate of 5.6 to 56 dm3 / min. The final one The large molecular chains are cracked in the second heating zone at temperatures from 750-8500 C. It is envisaged that the second heating zone will be a continuous reaction vessel is like an ejector in which the heater is under continuous uniform Movement is carried out.

As mentioned earlier, the main advantage of this process is the production of very desirable short chain carbon gases and themselves volatilizing liquids. The appearance of the resulting end products will be reasonable will depend on the appearance of the catalyst composition and will vary slightly depending on the type of organic material to be decomposed. Additionally the ratio of the gaseous products in the final mixture is limited to Increases in magnitude when a larger amount of catalyst is used. To At some point further additions of catalysts will of course have no effect have more on the production of gas products.

In addition to the above parameters, the appearance of the End products to a certain extent also depend on the temperature profile and the residence time of the material to be decomposed in the system. Some variation on the By-products can also be through Changing the temperatures of the first two mixing zones as well as by increasing or decreasing the conveyor speed, with which the materials traverse the device can be achieved.

The gas chromatography analysis of the collected after treatment Gases indicates that the gases are mainly unsaturated with minor amounts of also present saturated gases. The following gases were generated (in descending order Order in the concentration in which they usually occur): ethylene, propylene, 2-butene (cis and trans), 1-butene, ethane, methane, propane and butane. When mixed Thermoplastic products are decomposed, so does everyone in general Main product formed into a monomeric unit of the polymer or a polymer more complete decomposition product such as methane.

Those generated in the process of the present invention are volatile Liquids turned out to be hydrocarbons with carbon chain links with 5 to 12 carbon members and predominantly from C5 to C6. Infrared and gas chromatography analysis of the volatile liquids show a predominant presence of l-pentene or other short unsaturated carbon chain gases that result from those from the fractional distillation of gasoline obtained are similar.

The formed liquids are in a cooled consensator separator, which is attached to the output end of the second pyrolysis zone, collected. The gases are smuggled through this, separated and collected in a range of cold separators ranging in temperatures from OOC to -196 ° C. In practical applications of the method it is envisaged that a composition of combustible liquids and gases from the system at a constant level can be branched off and used as fuel or further processed for the rebuilding of new organic compounds. So the process can become one run closed circuit, with no gaseous air pollution elements to be released. Salts or other solid residues left during the process can also be collected in special separators.

As mentioned earlier, the appearance of the final products that of this thermochemical decomposition of high molecular weight organic material obtained vary over a wide range. However, it can be expected that the process is on average about 20.5 to 94.0% gases, about 0.9 to 78.5% Liquids (which include both highly volatile flammable liquids and Low viscosity fuel oils include), and about 0 to 1,668 of tar-containing ones Substance produced. In addition, about 0 to 15% incombustible solids always result the melt treatment of various solid organic materials.

The particular embodiments of the invention are set out below explained with three examples.

Example 1 100 parts of particles of a given size, produced the end Crushed discarded bottles made of polyethylene are about 0.33 parts by weight a mixture of the metal oxides of barium, chromium and copper (commercially available as To obtain "copper ore") premixed and poured into the funnel of a first continuous Screw extruder filled. At the same time, about 0.66 parts by weight of Dibenzoyl peroxide with a minimum content of active oxygen of 8.0% was added. When the thermoplastic polymer-catalyst mixture through the screw extruder gets through, it is heated to about 500 ° C, thoroughly mixed and the Comminution reaction started. The melted mixed materials will be then passed through a closed system into a second screw extruder.

Inside the closed flow area between the extruders dry nitrogen gas is added at a pressure of approx. 0.28 bar at a Inflow rate of approx. 28.1 dm³ per minute. The heating takes place in the second screw extruder continued down to temperatures between 750-800 ° C and the products in refrigerated Cutting devices collected.

After collecting the on products, analysis showed 83% 83% combustible Gas on a weight basis, 13:58 combustible, room temperature condensable organic Liquids with carbon chain connections from C5 to C12 and solid gases, for example Money. Gas chromatography analysis of the collected gases showed approximately 60% up to ethylene, 25% methane and the rest distributed between C3 to C5, largely unsaturated Hydrocarbons. The analysis of the volatile liquids shows the presence a substantial amount of the linear OC olefins, the 1-hexene and 1-pentene contained. The carbonaceous residue could be obtained by heating on white heat cannot be burned further with a propane flame.

In the same way was the process of the present invention successfully applied for the conversion of the thermoplastics indicated below Materials either in a separate order of the individual substances or as mixtures of different plastic materials. in different amounts: linear polyethylene (high density) low density polyethylene polyallomeric polypropylene polycarbonate Polyamide (nylon) polyvinyl chloride polyvinylidene fluoride (saran) polystyrene polyethylene terephthalate Acrylonitrile butadiene styrene Cellulose acetate Styrene acrylonite (SAN) Chlorinated polyether Acetal Copolymers Example 2 Solid waste mixtures were prepared according to that issued by the US Navy specified standard (called "Marine Waste") and developed according to the present Invention treated. This solid waste mixture consists of a percentage of 10.7 wood, 37.3 paper, 3.7 mixed clothes, 0.42 rubber, 0.42 plastic and 47.3 wet kitchen waste and it is estimated that this is a typical mix is from the residues that arise on board a ship and are thrown away. This mixture is poured into a reaction vessel, then first 2% copper oxide, then 1% dibenzoyl peroxide with a minimum active oxygen content of 8%, be added, the peroxide being added before the Copper oxide is thoroughly mixed in the mixture. The resulting mixed catalyst compound is thoroughly agitated and heated to approx. 3750 C. It then goes into a screw extruder, where heating is continued up in an atmosphere of dry nitrogen to a temperature of approx. 8000 C.

After the capture, the analyzed products gave on average approx. 85% gases, a trace of volatile organic liquids and approx. 14% Solids. This example demonstrates the very effective utility of the present Invention when used to decompose urban waste. The only ones By-products are valuable, non-polluting gases and an inert coblene residue, which serves as agricultural fertilizer.

Example 3 Spent motor oil mixed with up to 20% artificial Sea water, up to about 92% by weight, was in short chain hydrocarbons converted using the mixed metal oxides according to Example 1 with di-t-butyl peroxide in a catalyst composition of 1 part metal oxides up to 2 parts peroxides. The ratio of the mixed catalyst to the waste oil was 1 part catalyst to 100 parts of oil / seawater mixture.

The procedure was applied in a similar manner to the Achieving thermochemical decomposition of waste lubricants and waste petroleum products. The decomposition of petroleum waste, for example, included hypoid gear lubricants, Motor oils, automatic transmission fluids, hydraulic oils and wheel bearing grease with a.

In all cases there was a 90% conversion to low molecular weight Hydrocarbon gases and volatile liquids are effected.

Claims (7)

Claims 1. A process for the thermal decomposition of high molecular weight organic material, in particular of thermoplastic polymers, oils and fats and their compounds, to low molecular weight hydrocarbon compounds with 1 to 12 carbon atoms, characterized in that this organic material is heated to temperatures between 750 and 8500 C in an opposite the decomposition reaction in an inert gas atmosphere and with the aid of an effective amount of a two-component pyrolysis catalyst system, which is composed essentially of: a) 1 part to 99 parts of a first pyrolysis catalyst from a group of heavy metal oxides, oxide-generating compounds of heavy metals and mixtures thereof, and b) 99 parts to 1 part of a second pyrolysis catalyst selected from the group of compounds having the following structural formula: where R is a hydrocarbyl and R 'is hydrogen or a hydrocarbyl. 2. The method according to claim 1, d a d u r c h g e -k e n n z e i c h n e t that the ratio of the first pyrolysis catalyst to the second pyrolysis catalyst in the two-component pyrolysis catalyst system is about 1: 3 to 3: 1. 3r method according to claim 1 or 2, d u r c h e k e n n z e i c h n e t that the first pyrolysis catalyst is an oxide of barium, chromium, copper, Lead, zinc, bismuth and nickel and compounds thereof. 4. The method according to claim 3, d a d u r c h g e -k e n n z e i c h n e t that the first pyrolysis catalyst is a mixture of barium, chromium and Is copper oxides. 5. The method of claim 1, d a d u r c h g e -k e n n z e i c h n e t that the second pyrolysis catalyst from the group consisting of ketone peroxides, Peresters and alkyl hydroperoxides is selected. 6. The method of claim 1, d a d u r c h g e -k e n n z e i c h n e t that the second pyrolysis catalyst is t-butyl hydroperoxide. 7. The method according to claim 1 to 6 for thermochemical decomposition of high molecular weight thermoplastic material, especially polyolefins, for example Polyethylene, in its molecular structure carbon and carbon atom compounds prevail that the thermoplastic polymeric material with about 0.05 to 5.0 parts by weight of a first pyrolysis catalyst is mixed, which consists of the oxides and oxygen-generating components of heavy metals and compounds such that the thermoplastic material is about 0.15 up to about 15.0 parts by weight of a second pyrolysis catalyst is mixed, which consists of organic peroxides that the mixing of the first and second Pyrolysis catalyst takes place one after the other, with the addition of one only completed will when the other is already thoroughly familiar with it the thermoplastic polymeric material is mixed, then that from the combination of the first and a second pyrolysis catalyst achieved with the thermoplastic polymeric material Mixture is heated in a first heating zone at temperatures below 5000C until this mixture is in a thoroughly molten state, followed by heating in a second heating zone in an atmosphere opposite that taking place Reaction is inert, continued to a temperature between about 800 to 9000C and the heating in this second heating zone is continued until the thermoplastic polymeric material is almost completely replaced and low molecular weight has produced organic constituents that have between 1 and 12 carbon atoms and a small part of incombustible coal residues, and that this low molecular weight organic material is then recovered.