EP2812109A1

EP2812109A1 - Method for performing mechanical, chemical and/or thermal processes

Info

Publication number: EP2812109A1
Application number: EP13707287.2A
Authority: EP
Inventors: Daniel Witte
Original assignee: List Holding AG
Current assignee: LIST TECHNOLOGY AG
Priority date: 2012-02-10
Filing date: 2013-02-08
Publication date: 2014-12-17
Also published as: TW201336584A; CA2863853A1; JP2015509444A; US20160009855A1; KR20140129063A; WO2013117677A1; BR112014019591A2; CN104159664A; SG11201404646WA; RU2014128904A

Abstract

In the method for performing mechanical, chemical and/or thermal processes in a reactant and/or product in a housing that has at least one feed point, at least one catalyst is mixed into the reactant, as a result of which the product reacts up to a desired degree of conversion. In this process, the reactant is mixed with the catalyst before being introduced into the housing.

Description

Method for carrying out mechanical, chemical and / or thermal processes

In a method for carrying out mechanical, chemical and / or thermal processes in a starting material or product in a housing which has at least one feed point (feed point), wherein the starting material at least one catalyst is admixed, through which the product to a desired Turnover level reacts.

State of the art

Such devices are performed for example in mixing kneaders. These serve very diverse purposes. First of all mention should be made of evaporation with solvent recovery, which is carried out batchwise or continuously and often under vacuum. As a result, for example, distillation residues and in particular toluene diisocyanates are treated, but also production residues with toxic or high-boiling solvents from chemistry and pharmaceutical production, washing solutions and paint sludge, polymer solutions, elastomer solutions from the solvent, adhesives and sealants.

With the apparatuses is also a continuous or batchwise contact drying, water and / or solvent-moist products, often also under vacuum, performed. The application is intended primarily for pigments, dyes, fine chemicals, additives such as salts, oxides, hydroxides, antioxidants, temperature-sensitive pharmaceutical and vitamin products, active ingredients, polymers, synthetic rubbers, polymer suspensions, latex, hydrogels, waxes, pesticides and residues from the chemical or pharmaceutical production, such as salts, catalysts, slags, waste liquors. These processes are also used in food production, for example in the production and / or treatment of block milk, sugar substitutes, starch derivatives, alginates, for the treatment of industrial sludges, oil sludges, biosludge, paper sludge, paint sludge and generally for the treatment of sticky, crusty viscose products, waste products and cellulose derivatives.

In a Mischkneter a polycondensation reaction, usually continuously and usually in the melt, take place and is mainly used in the treatment of polyamides, polyesters, polyacetates, polyimides, thermoplastics, elastomers, silicones, urea resins, phenolic resins, detergents and fertilizers. For example, it has application to polymer melts after bulk polymerization to derivatives of methacrylic acid. It is also possible to carry out a polymerization reaction, likewise usually continuously. This is applied to polyacrylates, hydrogels, polyols, thermoplastic polymers, elastomers, syndiotactic polystyrene and polyacrylamides. In mixing kneaders, degassing and / or devolatilization may take place. This is applied to polymer melts, after (co) polymerization of monomer (s), after condensation of polyester or polyamide melts, on spinning solutions for synthetic fibers and on polymer or elastomer granules or powder in the solid state.

In general, solid, liquid or multiphase reactions can take place in the mixing kneader. This is especially true for baking reactions, in the treatment of hydrofluoric acid, stearates, cyanides, polyphosphates, cyanuric acids, cellulose derivatives, esters, ethers, polyacetal resins, sulphanilic acids, Cu phthalocyanines, starch derivatives, ammonium polyphosphates, sulfonates, pesticides and fertilizers.

Furthermore, reactions may take place solid / gaseous (e.g., carboxylation) or liquid / gaseous. This is used in the treatment of acetates, acids, Kolbe-Schmitt reactions, e.g. BON, Na salicylates, parahydroxibenzoates and pharmaceuticals.

Reactions liquid / liquid occur in neutralization reactions and transesterification reactions.

Dissolving and / or degassing in such mixing kneaders takes place in spinning solutions for synthetic fibers, polyamides, polyesters and celluloses.

A so-called Flushing takes place in the treatment or production of pigments. A solid state postcondensation takes place in the production or treatment of polyesters, polycarbonates and polyamides, a continuous mashing eg in the treatment of fibers, eg cellulose fibers with solvents, a crystallization from the melt or from solutions in the treatment of salts, Fine chemicals, polyols, alcoholates, compounding, mixing (continuous and / or batchwise) in polymer blends, silicone compounds, sealants, fly ash, coagulating (especially continuous) in the treatment of polymer suspensions.

In a mixing kneader also multifunctional processes can be combined, for example heating, drying, melting, crystallizing, mixing, degassing, reacting - all this continuously or in batches. This produces and / or treats polymers, elastomers, inorganic products, residues, pharmaceutical products, food products, printing inks.

In mixed kneaders, vacuum sublimation / desublimation may also occur, thereby reducing chemical precursors, e.g. Anthrachinon, metal chlorides, ferrocenes, iodine, organometallic compounds, etc. are purified. Furthermore, pharmaceutical intermediates can be prepared.

A continuous carrier gas desublimation takes place, for example, in organic intermediates, for example anthraquinone and fine chemicals. Essentially, a single-shaft and two-shaft mixing kneader are distinguished. A single-shaft mixing kneader is known, for example, from AT 334 328, CH 658 798 A5 or CH 686 406 A5. In this case, an axially extending, occupied with disc elements and rotating about a rotational axis in a rotational direction shaft is arranged in a housing. This causes the transport of the product in the transport direction. Between the disc elements are Counter-elements fixedly mounted on the housing. The disc elements are arranged in planes perpendicular to the kneader shaft and form between them free sectors, which form with the planes of adjacent disc elements Knüräume.

A multi-shaft mixing and kneading machine is described in CH-A 506 322. There are on a shaft radial disc elements and arranged between the discs axially aligned kneading. Between these discs engage from the other wave frame-like shaped mixing and kneading elements. These mixing and kneading elements clean the disks and kneading bars of the first shaft. The kneading bars on both shafts in turn clean the inside of the housing.

A mixing kneader of the abovementioned type is known, for example, from EP 0 517 068 B1. With him turn in a mixer housing two axially parallel shafts either in opposite directions or in the same direction. In this case, mixing bars applied to disk elements interact with each other. In addition to the function of mixing, the mixing bars have the task of cleaning product-contacted areas of the mixer housing, the shafts and the disk elements as well as possible and thus avoid unmixed zones.

Furthermore, from DE 199 40 521 A1 a mixing kneader of the above-mentioned type is known in which the support elements form a recess in the region of the kneading bars so that the kneading bar has as large an axial extent as possible. Such a mixing kneader has excellent self-cleaning of all product-contacting surfaces of the housing and the waves, but has the property that the support elements of the kneading bars due to the paths of the kneading bars make recesses necessary, which lead to complicated Tragelementformen. task

The object of the present invention is to improve the reaction process in the educt or in the product.

Solution of the task

To achieve the object, the educt is mixed with the catalyst before it is introduced into the housing.

The process, which is the subject of this invention, is based on a catalytic reaction, wherein the conversion and thus the necessary size of the reactor or the residence time of a mixture of reactant and product in the reactor of the concentration of catalyst in the mixture of starting material and Product of the reaction depends. The starting material and the product, as well as the catalyst should be well mixed or even better soluble in each other.

These are, above all, processes for the catalytic polymerization or reaction of monomers or other starting materials with increased conversion. It should be a reaction in which there is no or only temporarily to the formation of intermediates. An example which may be mentioned is the polymerization of polylactides (PLA), which is carried out by catalytic ring-opening polymerization of lactides. Typical of this reaction is that the monomer is thoroughly premixed with the catalyst and then fed to a polymerization reactor. The polymerization reactor is typically continuous, since the end product is viscous and thus poorly flowable. Therefore, horizontal mixing kneaders, screw extruders, stirred tanks or ring reactors with static mixers are used. All of these reactor types have in common that during the Polymerization a mixing of the polymer with the catalyst and the monomer must be guaranteed. Only in this way is it possible to produce high molecular weight PLA. While the reactor types differ with regard to the possibility of achieving high conversion rates, it is common that the reaction rate in a first approximation depends linearly on the catalyst concentration. Unfortunately, the best catalysts are zinc based, which can give rise to toxic degradation products. The concentration of catalyst must therefore be limited, but then increases the reaction time. As a result, unwanted side reactions also have more time to develop, which leads to a deterioration of the product properties. These side reactions can be counteracted by lowering the temperature, but this further slows down the reaction rate.

The inventive method improves the mentioned limitations by the catalyst is mixed with a partial amount of the educt and then fed to the polymerization reactor. Since the catalyst concentration is higher, the reaction rate is correspondingly faster. The largely thoroughly reacted product is mixed with a further subset of starting material. The reaction rate will now be slower. This process is repeated until the total amount of starting material has been mixed in and reacted through. The concentration of catalyst is therefore identical to the case where the starting material was completely mixed in advance with catalyst, but the reaction was initially faster. When this idea of the process is transferred to a continuous process, the benefits become truly visible. The continuous process always uses the completely available reactor volume. However, since the required residence time of the first feed point is shorter, the distance to the second feed point can be reduced. The same applies to the following feed sites. As an example, let us say that the reaction is of the first order and linear of the Depend on catalyst concentration. Then the required residence time will triple when the amount of catalyst is reduced by a factor of three. However, if the feed is distributed over three identical feed points, an increase of the required residence time by only 35% (instead of 200%) results at a distance of 25% between feed point 1 and 2, and of 25% between feed point 2 and 3.

If the continuous process is partially remixed along the length, a further advantage of the method according to the invention results from the fact that the back-mixed area around each individual feed point can be set separately with regard to the degree of conversion and the temperature level. Many reactions are exothermic and therefore require accurate temperature control. In the back-mixed process, the temperature level is set when starting the process and then kept on the energy balance. If there is only one feed point, only one temperature level can be adjusted. The portion of the reactor downstream, which is not adequately remixed with the area of the feed gets its feedstock with educt and product from the previous back-mixed apparatus part and is therefore not independently regulate. At several feed points, the degree of conversion and the temperature level over the entire reactor space can be adjusted by controlling the other feed points in terms of time and quantity. For this purpose, separate protection is sought after.

Partially back-mixed reactors are, for example, large-volume, horizontal kneaders, the mixing in the wave direction being hindered by corresponding installations on the shaft or the housing. These apparatuses have a good radial and tangential mixing effect. The product flow and thus the orientation of the backmixing is therefore realized in the wave direction. The accompanying drawing is a graphical representation of the process of the invention

Claims

Claims:

1 . A process for carrying out mechanical, chemical and / or thermal processes in a starting material or product in a housing which has at least one feed point (feed point), wherein the reactant at least one catalyst is admixed, through which the product reacts to a desired degree of conversion , characterized in that the educt at a plurality of feed points in time and / or quantitatively different is entered into the housing.

2. A method for carrying out mechanical, chemical and / or thermal processes in a starting material or product in a housing which has at least one feed point (feed point), wherein the starting material at least one catalyst is admixed, through which the product to a desired Reactive reacts, characterized in that the educt is mixed before entering the housing with the catalyst.

3. The method according to claim 1 or 2, characterized in that the amount of the starting material is divided into portions with catalyst and added in a batch process staggered in time to the reactor.

4. The method according to claim 1 or 2, characterized in that the amount of educt with catalyst in a continuous process is spatially separated via separate feed points added to the reactor.

5. The method according to claim 4, characterized in that in the continuous process between the feed points, the back-mixing is hindered or prevented.

6. The method according to at least one of the preceding claims, characterized in that the amount of catalyst is entered completely or for the most part together with the first input into the reactor amount of the reactant or in the continuous process in the direction of product flow in the first-placed feed point.

7. The method according to at least one of the preceding claims, characterized in that it is a polymerization reaction.

8. The method according to claim 7, characterized in that it is a ring-opening polymerization.

9. The method according to at least one of the preceding claims, characterized in that an initiator is added to start the reaction.

10. Device for carrying out mechanical, chemical and / or thermal processes in a housing (3) with mixing and cleaning elements (5) on shafts (1, 2), wherein the mixing and cleaning elements (5) of the shafts (1, 2) engage in their rotation about their axes,