PROCEDURE FOR SPLITTING AND HYDROGENATION OF POLYMERS

The invention concerns muddled for splitting of polymers, in particular for the recycling of plastics.

The recycling of plastics gains ever more significance, there it substantially for the saving of energy, raw materials and dump area contributes. Past procedures for the recycling of plastics are enough from the burn to the hydrogenation in sump phase reactors or in Hydrocrackern for the production of mineral oils. Depending upon kind of the procedure different problems and disadvantages arise.

The burn is e.g. a final utilization, which permits only the use to the freed heat of combustion. Besides the burn of plastics has to avoid the disadvantage that during the processing special conditions must be kept, in order the formation of dioxins, in particular with the burn of PVC, surely.

With the production of gases from polymers by means of pyrolysis, a further procedure for the utilization of plastics, the molecular structure of the polymers is reduced to a large extent, which limits the employment these gases for the production of high-quality products very strongly.

Also training old plastic in plastic mixtures, supplies only products, which are less high-quality than such, which do not contain portions of old plastics. Admits e.g. is the production of noise protection walls, flower excavator buckets and such a thing from old plastics.

In contrast to the procedures specified so far however also Vewertungsverfahren are well-known from the state of the art, with which mineral oils win themselves by a splitting and a one to it following hydrogenation by polymers. With these procedures it acts around the degradative extruding for polymer liquefaction as well as the initially mentioned hydrogenation of polymers under high pressure in sump phase reactors or Hydrocrackern for the production of mineral oils. The operating conditions are characterised with the procedures mentioned with high pressure and temperatures. Operating pressures of up to 400 bar and temperatures up to 500 DEG C are usual. Thus a high expenditure to energy and a complex constructional and organization in terms of safety of the plants is necessary for the execution of these procedures.

The invention is therefore the basis the task to make a procedure available which from the state of the art admitted disadvantages avoids.

The task is solved according to invention by a procedure of the initially mentioned kind by the fact that the polymers in a first process step are given to a reactor, which contains at least a liquid phase, and that the polymers in a second process step with ultrasonic in the liquid phase are broken open and in such a way received reactive polymer fragments in one already move directly following reaction with, at the time of developing the polymer fragments in the reactor existing reaction partner to the connections, which as final products of the procedure are isolatable and whose reactivity is so small that they are not received under the procedural conditions networking reactions.

The procedure according to invention uses thereby the fact that polymers are degradable by means of ultrasonic (A. Salzay, “The destruction OF highly polymerized molecules by ultrasonic waves”, Z. physical one chem. A164, 234-240 (1933)).

With the use of ultrasonic in liquid systems it comes to the training of so-called cavitations. If these cavitations collapse, develop “hot spots”, i.e. microscopic ranges in those develop for some microseconds very high temperatures (until approx. 5000 DEG C) and very high pressures (up to 500 bar) arise, without this leads macroscopically to a noticeable change of the appropriate operating parameters.

If such cavitations in the proximity of the surface of polymer particles form, then it can come both to the liquefaction of the polymers, whereby a mixture with the liquid phase can enter, and to the splitting off from mole cooling fragments.

The subject of the registration is accordingly a combination of splitting of polymers by means of ultrasonic with suitable Folgereaktionen. Here it is contrary to from the conditions the technology admitted procedures possible to keep during the rewho valuation of polymers macroscopic conditions which are to be handhad easily.

The reaction is according to invention intended, in which the polymer fragments produced in the second process step are converted to as final products isolatable connections to select according to in the procedure for processing polymers. As such reactions downstream find prefer the catalytic hydrogenation, the soaping and/or hydrolysis, ammonolysis or Alkoholyse application.

A surprising result of the combination according to invention of splitting of polymers by means of ultrasonic with a following catalytic hydrogenation exists in the fact that the assigned polymers are reduced to low-molecular products, which are further processable in usual refinery procedures and can thus an appropriate cycle in the Petrochemie be supplied. Further it is favourable that in the raw material contained Heteroatome on the reaction conditions are at least partly transferred in their wasserstoffverbindungen or appropriate salts.

In a special arrangement of the procedure according to invention the liquid phase consists of water or a mixture of water and at least an organic solvent. With the fact it is favourable that and for subsequent treatment in usual refinery procedures only the aqueous phase must be able themselves to enrich the procedure products in the organic phase be separated. Beyond that the salts formed from the Heteroatomen contained in the polymers separate in the aqueous phase.

In a further arrangement of the procedure according to invention, whereby the liquid phase is at least partly formed by water, the hydrogenation catalyst than catalyst forerunners is contained of an Raney alloy of aluminum and/or silicon with at least one metal from the group in form of nickel, cobalt, iron, copper or molybdenum in the liquid phase. About it is possible to produce the Raney catalyst in situ whereby the hydrogen for the hydrogenation, freed with the production of the catalyst, can be used. Beyond that the decomposition of the Raney alloy enters a continuous activity of the catalyst ensured to the actual Raney catalyst with use of ultrasonic substantially faster than so far usual and in addition is by the effect of ultrasonic over long time, since the metal surface is released again and again by the influence from ultrasonic from passivating deposits and/or such passivating deposits under ultrasonic influence even to form.

It proves itself further as particularly favourably, if the pH value of the liquid phase, in which the Raney alloy is contained, is increased by addition of alkali and/or alkaline-earth hydroxides and/or - oxides or by addition of an aqueous solution of these connections before exposing to sound with ultrasonic. It is particularly favourable, if unittelbar after addition by at least a Alkalie the second process step is accomplished, so that the activation of the catalyst accelerated and the hydrogen developing thereby is involved at least partly in the hydrogenation of the molecule fragments. In this way the largest part of the hydrogen, which develops with the production of the Raney catalyst, for the hydrogenation of the polymer fragments produced under ultrasonic effect can be used.

In another favourable arrangement of the procedure according to invention will a dispersion, like it described was given to an Raney alloy already above, in an aqueous alkaline solution before the execution of the second process step to the reactor. Around as large a part of the hydrogen for the hydrogenation of the molecule fragments, as possible developing developing from the dispersion, under ultrasonic effect to use to be able it is of advantage again special, if the second process step is accomplished directly after addition of the dispersion.

In a further favourable arrangement of the procedure according to invention a Raney catalyst already activated is preferably used. Since it is no longer necessary with a Raney catalyst already activated to extract alloying constituents by means of a caustic solution from the catalyst forerunner the liquid phase can consist thus also exclusively of an non-aqueous solvent or solvent mixture.

From the execution of the procedure according to invention with non-aqueous advantage resulting up to the water-free liquid phase it lies in the fact that before the subsequent treatment of the reaction products no additional process step is necessary, in order to separate the otherwise existing water from the liquid phase. This advantage will be very large particularly then if solvent or products from the liquid phase distillative removed and/or be separated should and the connections which can be separated able is to form with water Azeotrope.

The procedure according to invention offers beyond that the special preference/advantage, to hydrogenation catalysts from other hydrogenation procedures, like e.g. fat hardening for margarine production, already used, begins to be able. These catalysts usually possess a relatively small activity, because their catalytically active surface was at least partly blocked with the past use by impurities.

If the activity of the catalysts sinks under a certain limit value, it is usually only possible with the well-known catalysis procedures to regenerate or dispose of the catalyst in a complex procedure, whereby both possibilities often cause a very large expenditure.

In the procedure according to invention these can be used in their activity clearly decreased catalysts however, because the catalyst surface under the effect of ultrasonic is released from the matured impurities and thus the catalyst activity is again increased.

The kind of the catalysts used for the hydrogenation is accordingly also not limited to Raney catalysts. The use e.g. of palladium, platinum, rhodium or similar metals as catalysts in the procedure according to invention is just as possible.

Further it is with the procedure according to invention of special advantage to introduce during the second process step additionally hydrogen into the liquid phase in order to in this way guarantee as complete and immediately a hydrogenation of the polymer fragments as possible taking place after the connection splitting.

The special use of this procedure is justified in the fact that by the immediate hydrogenation of the molecule locations of fracture a Folgereaktion, like a networking reaction, becomes e.g. prevented or impossible. Straight this is of special importance, since according to invention the polymere material used in the procedure is to be reduced and not interlaced more highly.

In a further arrangement of the procedure according to invention during the second process step Carbon monoxide is introduced into the liquid phase. Here it is appropriate, if the reactor a containing catalyst contains an iron, chrome, copper, zinc and/or alumina, so that introductory Carbon monoxide with the water contained appropriately in the liquid phase is converted catalytically to hydrogen and carbon dioxide, whereby with the hydrogen developed in such a way the polymer fragments are catalytically hydrogenated.

In a particularly favourable arrangement of this procedure during the second process step synthesis gas, water gas or another, essentially Carbon monoxide and Wasserstoff containing process gas, into the liquid phase are introduced. The special advantages of this procedure are in the fact justified that one avoids to use relatively expensive hydrogen gas.

In another arrangement of the procedure according to invention the polymer which can be split was preferably developed by a condensation reaction. Examples of such polymers are polyesters, PP or such a thing.

It is particularly favourable to convert those by ultrasonic effect in the second process step of polymer fragments developed of polyesters by a soaping reaction to as final products of the procedure isolatable connections. Thereby the parent compounds are again available for polyester production, so that a complete recycling cycle is created.

Further particularly preferential reactions to the Ümsetzung of the polymer fragments produced in the second process step by means of ultrasonic are the Alkoholyse, ammonolysis or such a thing.

In addition the procedure according to invention is very economical, since no all too high demands are made to pressure and temperature against the material which can be split and processing parameters as in particular in a range to lie, which is reached without special constructional expenditure or high employment at energy. Thus the procedure does not work at an operating pressure from 0,1 to 10 bar and a temperature from 0 to 150 DEG C. further is necessary preferably it to use those polymers which can be split sort clean in the procedure. Beyond that it is of advantage however to cut up that material before the execution of the procedure, which can be used. This can be clarified best by the example by plastic wastes, there with cutting up to powder, granulates or geschreddertem plastic at the same time certain homogenization of the different portions of the assigned plastic wastes effected. Even if the assigned material contains of additives such as softeners, stabilizers, antioxidants, lubricants, coloring materials, flame protection means and other auxiliary materials usual in the polymer processing, this does not disturb the procedure according to invention, so that a very broad application of the procedure to most diverse polymers and plastics is possible.

During a special arrangement of the procedure according to invention the reaction products are removed depending upon more desired middle mol mass from the mixture. This is preferably done with distillation at the distance of reaction products with low boiling point and via extraction at the distance of high-molecular products.

The subject of the available registration is the moreover one a preferential execution form of the descriptive procedure, which is given by the fact that the liquid phase is formed by a liquid suitable for the Enthalogenierung of the polymer.

It is well-known to antichlor for example polyvinyl chloride by bases. Suitable bases are alkaline solutions, amines, alkyl amides, etc.

These liquids can be used with the procedure according to invention as liquid phase, in order to implement so during the ultrasonic effect, which leads to the training of the cavitations in the liquid, the Dehydrohalogenierung of the polymer in an accelerated form. It is possible to make with the dismantling of the polymer by ultrasonic effect at the same time a very effective Dehydrohalogenierung.

The effectiveness is strengthened still by the fact that the ultrasonic effect in presence of a phase transfer catalyst is implemented. Phase transfer catalysts are well-known and are in particular quaternäre ammonium or phosphorus salts, Kronenether etc. in practical application prefer quaternäre ammonium salts begun.

The use of a phase transfer catalyst is suitable however not only for the Dehydrohalogenierung by halogenhaltigen polymers, but also for splitting of polymers, which were manufactured by a Gleichgewichtsreaktion. An important representative of these polymers is Polyethylenterephtalat (PET), which is degradable thus on use of a phase transfer catalyst with the procedure of the principal patent.

The subject of the available registration is from there also a preferential execution form of the procedure with that the ultrasonic effect in presence of a phase transfer catalyst is made.

The polymers treated with the procedure in accordance with this registration can be inserted without a source treatment otherwise needed for the Dehydrohalogenierung, for example with tetrahydrofurane and butanol.

Those below listed test results clarify the Dehydrohalogenierung of PVC, as well as which is possible without swelling means with ultrasonic and employment of a phase transfer catalyst also the dismantling of PET, which is possible only with the employment of a phase transfer catalyst. Dehydrohalogenierung of PVC, without phase transfer catalyst: <tb><TABLE> Columns=8 <tb> <tb>Head Col 1: Ultrasonic <tb>Head Col 2: Employment <tb>Head Col 3: Solution/swelling means <tb>Head Col 4: Alkali <tb>Head Col 5: Temperature <tb>Head Col 6: Response time <tb>Head Col 7: Conversion <tb>Head Col 8: No. <tb> <SEP>nein<SEP>1 g PVC<SEP>Tetrahydrofuran, Butanol<SEP>NaOH<SEP>60 DEG C<SEP>1 Stunde<CEL AL=C>0,0%<CEL AL=C>3 <tb><SEP>ja<SEP>1 g PVC<SEP>Tetrahydrofuran, Butanol<SEP>NaOH<SEP>60 DEG C<SEP>1 Stunde<CEL AL=C>6,7%<CEL AL=C>4 <tb></TABLE> Dehydrohalogenierung of PVC, with phase transfer catalyst: <tb><TABLE> Columns=8 <tb> <tb>Head Col 1: Ultrasonic <tb>Head Col 2: Employment <tb>Head Col 3: Solution/swelling means <tb>Head Col 4: Alkali <tb>Head Col 5: Temperature <tb>Head Col 6: Response time <tb>Head Col 7: Conversion <tb>Head Col 8: No. <tb> <SEP>nein<SEP>1 g PVC<SEP>-<SEP>NaOH<SEP>60 DEG C<SEP>1 Stunde<SEP>3,1%<SEP>5 <tb><SEP>ja<SEP>1 g PVC<SEP>-<SEP>NaOH<SEP>60 DEG C<SEP>1 Stunde<SEP>3,6%<SEP>6 <tb></TABLE> dismantling of Polyethylenterephtalat, without phase transfer catalyst: <tb><TABLE> Columns=8 <tb> <tb>Head Col 1: Ultrasonic <tb>Head Col 2: Employment <tb>Head Col 3: Solution/swelling means <tb>Head Col 4: Alkali <tb>Head Col 5: Temperature <tb>Head Col 6: Response time <tb>Head Col 7: Conversion <tb>Head Col 8: No. <tb> <SEP>nein<SEP>2,5g PET<SEP>-<SEP>NaOH<SEP>80 DEG C<SEP>2 Stunden<SEP>0%<SEP>7 <tb><SEP>ja<SEP>2,5g PET<SEP>-<SEP>NaOH<SEP>50 DEG C<SEP>0,7 Stunden<SEP>0%<SEP>8 <tb></TABLE> dismantling of Polyethylenterephtalat, with phase transfer catalyst: <tb><TABLE> Columns=8 <tb> <tb>Head Col 1: Ultrasonic <tb>Head Col 2: Employment <tb>Head Col 3: Solution/swelling means <tb>Head Col 4: Alkali <tb>Head Col 5: Temperature <tb>Head Col 6: Response time <tb>Head Col 7: Conversion <tb>Head Col 8: NR <tb> <SEP>nein<SEP>2,5g PET<SEP>-<SEP>NaOH<SEP>60 DEG C<SEP>1 Stunde<SEP>3,6%<SEP>9 <tb><SEP>ja<SEP>2,5g PET<SEP>-<SEP>NaOH<SEP>60 DEG C<SEP>1 Stunde<SEP>7,12%<SEP>10 <tb></TABLE>

A schematic structure for the execution of the procedure is represented in figure 1.

By inlets 1 and 2 a supply is made from gases, Flüssigphase and to splitting polymer into an agitating boiler reactor 3. via 5 heat exchangers fed over a heat exchanger inlet 4 and a heat exchanger discharge opening the agitating boiler reactor 3 is kept at a moderate temperature, so that the liquid phase contained in the agitating boiler reactor is adjusted on an optimal temperature, if it is rolled over by a pump 6. After the pump 6 an ultrasonic flow cell 7 follows in river direction, in which splitting the polymer contained in the liquid phase as well as the reaction take place to the isolatable final products. A controlling of the flow rate been made via the ultrasonic flow cell 7 by the regulation of the pumping performance of the pump 6.In of a stage following to the ultrasonic flow cell 7 is fed an extraction place 8, in which high-molecular fission products are removed from the liquid phase, before this arrives again into the agitating boiler reactor 3. Low-molecular fission products are exhausted preferentially over a discharge opening line 9 from the agitating boiler reactor 3.