DE19826303A1 - A method for the comparative determination of physically or chemically induced heat coloration using infrared camera imaging - Google Patents

Abstract

A method for the comparative determination of physical or chemical process-induced heat coloration, uses infrared (IR) camera imaging. The images are taken before and after the processes and the IR emission are subtracted.

Description

The invention relates to a method for comparative determination of Properties of the materials of a combinatorial library using a Infrared camera with which the heat tone in the form of a differential image chemical or physical processes is registered. In the application DE 197 57 754.7 from December 23, 1997 are the essential features of the invention already described. The present application contains an extension of Process through the use of selective IR filters, its use for general characterization of material properties, its use for homogeneous catalysts and an improved embodiment with Library plates with low IR reflectivity, e.g. B. slate slabs.

State of the art

The greatest bottleneck in the development of new materials is discovery suitable new lead structures. This applies in particular to new catalysts. Despite the widespread use of heterogeneous and homogeneous Catalysts in chemical engineering and more extensive in this regard Research effort is the detailed mechanism of action heterogeneous and homogeneous catalysts under technical reaction conditions not sufficiently known. One is therefore on empirical Procedures to find the right kata for every application select analyzer materials and find reaction conditions under which have a desired catalytic activity and selectivity. Classic Catalyst testing procedures require that each be considered What catalyst material is tested individually under reaction conditions in view of the unmistakable abundance of possible materials a very represents a costly and time-consuming procedure. One The combinatorial field offers a promising way out Materials science in order to provide a technically interesting reaction sensible pre-selection of heterogeneous or homogeneous catalyst materials to meet and the test procedure for few promising materials  restrict. While heterogeneous catalysts mainly for production of mass products and fine chemicals are dominant homogeneous catalysts in the production of enantiomerically pure active substances in the pharmaceutical sector and in tactility-controlled polymerization.

The methods referred to as combinatorial methods are based on a Carrier placed a large number of samples in a confined space. Based easily accessible physical measurands related to the desired property of the material, is then on each sample quick and reliable test for this desired property carried out.

In this way, new magnetoresistant materials [B. Gabriel, H. Chang, X. Sun, P.G. Schultz, X.-D. Xiang, "A Class of Cobalt Oxide Magnetoresistance Materials Discovered with Combinatorial Synthesis ", Science, 270, 273-275, 1995], new superconducting materials [X.-D. Xiang, X. Sun, G. Briceno, Y. Lou, K.-A. Wang, H. Chang, W.G. Wallace-Freedman, S.- W. Chen, P.G. Schultz, "A combinatorial Approach to Materials Discovery", Science, 268, 1738-1740, 1995] and new luminescent materials [X.-D. Sun, K-A. Wang, Y. Yoo, W.G. Wallace-Freedman, C. Gao, X.-D. Xiang, P.G. Schultz, "Solution Phase Synthesis of Luminescent Materials Libraries", Adv. Mater. 9, 1046-1049, 1997].

Also in the field of combinatorial chemistry of heterogeneous catalysts there are already corresponding publications [F. C. Moates, M. Somani, J. Annamalai, J.T. Richardson, D. Luss, R.C. Willson, "Infrared Thermographic Screening of Combinatorial Libraries of Heterogeneous Catalysts ", Ind. Eng. Chem. Res. 35, 4801-4803, 1996; R. C. Willson, "Catalyst Testing Process and Apparatus "US patent: PCT / US97 / 02756 International patent: WO 97/32208]. The authors describe an experiment in which an infrared Camera catalytic activity based on the resulting heat is detected. The detection sensitivity of the by the authors described construction was, however, relatively small, so that only the extreme  exothermic detonating gas reaction (14 kJ / g) was detected. It is about this not a reaction of technical importance. To be effective catalysts Examining for technically important reactions is above all a higher one Detection sensitivity of the measurement setup is necessary, and the detection must be performed that the registration of heat of reaction at lower Temperatures, different reactions and with the tiniest catalyst quantities is possible. The detection of catalytic activity of polymer-bound Catalysts in solution were demonstrated on coded beads (0.5 mm) [S.J. Taylor, J.P. Morken, Science 280 (1998) 268]. Here, the density of the Solution should be greater than the density of the beads, as this is only on the upper surface can be observed floating. The disadvantage here is the complex Coding technique, the need to use a solvent higher density than that of floating solid catalysts. Come in addition the problem of using uncorrected IR images, which is that due to the different emission properties, highly sensitive IR Cameras the presence of different materials on a surface display without reactions, which makes the practicality of these methods is severely restricted.

The reliable production of catalyst libraries is another important aspect. Combinatorial libraries are known, although largely restrict to the area of pharmaceutical application, but also in part on the production of libraries for development of new materials (B. Posner et. al, Trends in Biochemical Science 19 (1994) 145). Probably the most reliable and widely applicable method Combination is used to create combinatorial libraries of materials of ink-jet printer technology with computer control, which allows the new materials selectively by mixing solutions in the nanoliter range to generate and by targeted post-treatment in the examined Convert solids [X.-D. Sun, K-A. Wang, Y. Yoo, W.G. Wallace- Freedman, C. Gao, X.-D. Xiang, P.G. Schultz, "Solution-Phase Synthesis of Luminescent Materials Libraries ", Adv. Mater. 9, 1046-1049, 1997] The problem here, however, is the use of suitable synthesis conditions  allow with these mixed nanoliter solutions also defined catalyst and to produce other materials.

Description of the invention

We have now found that the smallest heat effects when chemical or physical processes reliably with an infrared camera can be made visible if a differential thermal image is registered, that results from the subtraction of the IR Emission intensities from the intensi obtained under reaction conditions acts results. As chemical or physical processes with heat toning chemical reactions, phase transformations, material transformation are suitable lungs, sorption processes (physisorption, chemisorption, adsorption, Desorption), absorption processes (absorption of molecules or electromag net radiation), magnetic induction. So the warming of the Physisorption of molecules from the gas phase to detect porosity in Materials are used. The warming of catalyzed reactions serves the detection of catalytic activity of materials. The warm shade of Phase transformations are used to detect changes in the substance. The warmth tint associated with surface reactions such as the formation of carbides or nitrides by reactions of alloys or mixed oxides with methane or ammonia is used to detect substance conversions. The heat The combination of chemisorption and surface detection reactivity, such as B. acidic or basic centers. The warm tone characterized by the absorption of electromagnetic radiation special absorption properties, such as UV absorption, X-ray absorption, or absorption of visible light. Heating by applying a magnet field detects magnetic properties. All of these properties are from of particular interest when specific materials stand out from the crowd differentiate significantly from other materials and thus potential new ones Represent lead structures.

The method is particularly interesting for the development of new ones Catalysts based on combinatorial libraries. As a procedure for  Production of combinatorial catalyst libraries with heterogeneous Surprisingly, catalysts are suitable for the sol-gel process as it is was partly described in DE-A 195.45042.6. We have beyond that found that the heat of reaction of homogeneously catalyzed reactions can be reliably made visible with this technology. The use Heat difference images also allow temperature calibration and thus a reliable assignment of the actual temperature increase on the active catalyst. This is for evaluating relative activities and Quantifications of catalytic activities of great importance.

The catalytic reactions are preferred among precisely controlled ones Conditions carried out in a hermetically sealed reactor with is provided with an IR-transparent window in order to register with the To enable camera.

Catalyst libraries consisting of catalyst components in the form of Metal oxides and / or mixed metal oxides are produced by first the precursors of the catalyst components to be examined as aqueous or alcoholic solution of silicon or metal compounds in the form of their Alkoxy derivatives, mixed alkoxy derivatives, their alkoxyoxo or acetyl Acetonate derivatives or in the form of their halides, nitrates, citrates or others Carboxylates over the surface of a plate which, for. B. of slate, metal or Steel, glass, ceramics or plastics are distributed, z. B. in hollows created by drilling holes in the plate. The catalyst Components can in particular be carbides, nitrides and zeolites act. The library plates are then dried and calcined. When manufacturing the catalyst library, it can be due to the surfaces properties of the library plate that the sol from the Bores creeping onto the surface of the library plate. This can prevent it if the library plate is not covered with catalysts Places is coated with a non-wetting, IR-transparent film, for example, if the coating is pre-drilled before drilling is taken.  

Not only solid bodies, but also gaseous molecules emit infrared radiation. The intensity of this thermal emission increases with temperature to. In particular by reflections of this emitted radiation on the reactor walls and on the surface of the catalyst library can be inhomogeneous Temperature increases are faked. Reflections on the catalyst Library are particularly uncomfortable because they are directly from the IR camera be captured. For this reason, the radiation properties of the Support material of the catalyst library of crucial importance. A Material with particularly low reflectivity, close to that of a black one For this reason, Strahlers is used as a carrier material for the catalyst library particularly suitable. This can also be done with a suitable coating achieve. The inside walls of the reactor should also have as little infrared as possible reflect radiation. This can be done, for example, by appropriate Achieve anti-reflective coatings. In addition, the carrier material for the catalyst library has the lowest possible thermal conductivity point so that at the catalyst points during the catalytic Reaction developed heat is not dissipated too quickly and one if possible large temperature increase can be achieved.

Wavelength ranges in which the gaseous reactants and products show particularly strong infrared activity are for the IR thermographic Temperature measurement is unfavorable, because here disturbing effects are intensified Absorption and emission of the gases occur. Such wavelength ranges can be hidden using a wavelength-specific infrared filter become. For gaseous hydrocarbons we have found that it is It is advisable to use such a filter to remove the particularly intense CH Hide vibrations.

IR thermography as described here is also suitable for the detection of catalytic activity of enantioselective homogeneous catalysts and Enzymes. By using enantiomerically pure reactants or Racemates can both differentiate the relative catalytic activity Catalysts and their enantioselectivity using IR thermography  detect. The reactions were the enantioselective acylation of 1- Phenylethanol with lipase [M.T. Reetz, A. Zonta, J. Simpelkamp, Angew. Chem. 107 (1995) 373-376] and the hydrolysis of chiral epoxides with Mn, Co and Cr salt complexes [M. Tokunaga, J.F. Larrow, F. Kakiuchi, E.N. Jacobsen, Science 277 (1997) 936-9389 in a small combinatorial library from 9 reaction solutions examined. With the help of IR thermographic Difference pictures could both the relative activity of the catalysts as well whose enantioselectivity is made visible at the same time.

The process is of course based on many other types of reactions, such as selective hydrogenations, selective oxidations, esterifications, pericyclic reactions, halogenations, dehalogenations, hydrogenolyses, hydrations, dehydrations, condensations, enantioselective reactions, polymerisation reactions, polycondensation reactions, oxidative couplings, and selective oxidations of olefins and Alkanes, in particular with air, H ₂ O ₂ or ozone with selective formation of epoxides, ketones, aldehydes, alcohols, carboxylic acids or anhydrides can be used. Even heat of reaction of such reactions in the liquid phase can be visualized very simply and effectively with the aid of an IR camera (Maier, Holzwarth, DE 197 57 754.7).

Examples Setup of the camera, correction of the detector and temperature calibration

In the following examples, an infrared camera from AIM des Type AEGAIS used with a PtSi (platinum silicon) detector 256 times 256 pixels are used as described below. The camera was on connected to a computer. The software (version 1.40 from 4.7.97) allowed the background to be subtracted so that only one at each pixel Temperature increase relative to the initial temperature is displayed.  

A 3.6 µm cut-on was made directly in front of the entrance window of the detector Infrared filter attached, which for infrared radiation with wavelengths shorter than 3.6 µm is impermeable. The inhomogeneity of the detector was determined by a two corrected point correction. For this purpose, IR images of the library were kept at 5 ° C half and above the reaction temperature (hydrogenation: 100 ° C, oxidation: 350 ° C, lipase catalysis: 30 ° C, metal-salen catalysis: 27 ° C). After reaching the reaction temperature before the start of the reaction, a further IR image of the catalyst library made. This was then by all subsequent IR images subtracted (offset) so that only temperature changes due to catalytic activity at the catalyst points corresponding color changes became visible. The temperature calibration was done by reading the catalyst library in the reactor at 6 temperatures and a subsequent fit of the individual pixels using a square Polynomials, a function provided in the camera software.

example 1 Combinatorial test procedure for screening the catalytic activity of materials on a library Construction of the reactor

Particular attention was paid to this when designing the reactor tet, as homogeneous a temperature distribution as possible within the reactor achieve. The reactor consists essentially of two parts, the reactor head with an infrared-transmissive barium fluoride window for observing the Catalyst library and the reactor block made of solid steel. The reactor head with the infrared-transmissive barium fluoride window is around 10 ° C angled. The heating elements are located in the lower part of the reactor. she are arranged so that the entire reactor block and the reactor head be heated as homogeneously as possible. The gas supply lines were from below through the reactor block into the reaction chamber with the catalyst library led to the gaseous starting materials before the reaction at the catalyst point preheat to the same temperature as the catalyst library. The Gas mixture was fed through many small holes around the circular one  Catalyst library were arranged around. This should make one possible homogeneous distribution of the gases in the chamber can be achieved.

Production of the silica brine

Silica and titania brine were produced and used with a microliter pipette corresponding holes are pipetted onto a slate library plate. After the solvent evaporated, the entire library became calcined. The plate was placed in a specially for observation with the infrared Introduced camera (see above) designed reactor. Then the Catalysts on the plate by annealing for three hours at 300 ° C in Hydrogen flow activated. Thereafter, attempts to hydrogenate 1- Hexin performed at 100 ° C. Lastly, the attempts at oxidation of isooctane and toluene with synthetic air at 350 ° C.

Silica sols were made according to the standard protocol of Klein et al. [P. Klein, S. Thorimbert, WF Maier, J. Catal. 163 (1996) 476-488]. Tetraethoxyorthosilicate served as the silica precursor. The following compounds were dissolved in the sol as precursors for the other elements: PdCl ₂ , Na ₂ PtCl ₆ , IrCl ₄ xH ₂ O, RuCl ₃ xH ₂ O, CoCl ₂ 6H ₂ O, Fe (acac) _3, Mn (acac) ₃ , (iPrO) ₃ VO, CrCl ₃ 6H ₂ O, Cu (acac) ₂ , Ni (acac) ₂ , ZnCl ₂ , Pd (acac) ₂ , RhCl ₃ 3H ₂ O.

Production of the Titania brine

With constant stirring, 1 ml of titanium isopropoxide (3.36 mmol) in 3.33 ml dry ethanol dissolved. After stirring for 30 minutes, 8.33 ml of 8N HCl admitted. After a further 5 minutes, 46.7 ml of 12 N HCl slowly added. Then 833 ml of ethanol were added. Last 833 ml of an ethanolic solution of the metal compound was added.

Production of the catalyst library

Slate was used as material for the catalyst library because of its thermal conductivity and its low reflectivity for infrared rays lung selected. The circular library plate (diameter 5 cm) stuck 69 holes with a diameter of 1.5 mm and a depth of 0.6 mm.  

The catalyst library was created by pipetting microliter quantities of the silica and titania brine into the holes provided on the slate plate. In order to obtain comparable amounts of catalyst material, 1.5 µl (corresponding to 192 µg silica) in the case of the Silca brine and 5 µl (corresponding to 182 µg Titania) in the case of the Titania brine were pipetted in. After the solvent had evaporated, the plate was calcined as in Example 1 (temperature program: 1. room temperature to 65 ° C. at 1 ° C./min, 2. temperature at 30 ° C. for 30 minutes, 3. 65 ° C. to 250 ° C. at 1 ° C / min, 4. keep temperature at 250 ° C for 3 h, 5. cool to room temperature). Fig. 1 shows the arrangement and chemical compositions of the library.

Hydrogenation of 1-hexyne

The hydrogenation of 1-hexyne was carried out by at a temperature of 100 ° C hydrogen at a flow rate of 20 ml / min was passed through the reactor. 1-Hexin was evaporated into the gas stream. The concentration of 1-hexyne in the gas phase was 0.2478 g / l.

An infrared image of the catalyst library during the reaction is shown in Fig. 2, the occupancy of the library can be seen in Fig. 1. The catalyst materials Pd ₅ Si, Pd ₁ Si, Pt ₅ Si and Pt ₁ Si show particular activity.

Oxidation of isooctane with synthetic air

Oxidation of isooctane was carried out by passing synthetic air through the reactor at a temperature of 350 ° C at a flow rate of 20 ml / min. Isooctane was evaporated into the gas stream. The concentration of isooctane in the gas phase was 0.2381 g / l. Fig. 3 shows an infrared image of the catalyst library during the reaction . The catalyst materials Pt ₂ Ti, Pt ₁ Ti, V ₅ Ti, Pd ₁ Ti, Ru ₅ Ti, Cu ₅ Ti show particular activity.

Oxidation of toluene with synthetic air

The oxidation of toluene was carried out by passing synthetic air through the reactor at a temperature of 350 ° C. at a flow rate of 20 ml / min. Toluene was evaporated into the gas stream. The concentration of toluene in the gas phase was 0.1489 g / l. Fig. 4 shows an infrared image of the catalyst library during the reaction . The catalyst materials Pt ₂ Ti, Pt ₁ Ti, V ₅ Ti, Cu ₅ Ti, Pt ₅ Ti, Pt ₅ Si show particular activity.

Example 2 Combinatorial test procedure for simultaneous activity and Enantioselectivity screening of homogeneous catalysts

Catalytic reactions in the liquid phase were in the wells of a modified microtiter plate. This plate was on a thermo statable Eppendorf shaker attached. By shaking the Microtiter plate made it possible to mix the reaction homogeneously to achieve solutions in the individual wells of the plate and the solutions conditions to certain predetermined temperatures. Of the The IR camera was adjusted as described in the previous example. There was constant shaking during the reaction. For the measurement with the The infrared shaker was briefly stopped. In the experiment, one Library of 9 reactions observed simultaneously.

Lipase-catalyzed enantioselective acylation of 1-phenylethanol with Vinyl acetate

100 µl of a solution of phenylethanol as S-enantiomer, R-enantiomer or racemate in toluene were pipetted into the wells of the microtiter plate. 100 μl of a solution of the vinyl acetate in toluene in an equimolar ratio was added to these solutions. Concentrations of 0.5 M, 1 M or 2 M were used. Now infrared images of the plate with the solutions for the temperature calibration, the two-point correction of the detector and the offset were taken. The reaction was then started by adding 5 mg of the immobilized lipase (candida antarctica, Novo SP 435) at 30 ° C. and infrared images of the plate with the solutions were taken at various times during the reaction. Fig. 5 shows that the heat development in the racemate (left column) is less than in the R enantiomer of 1-phenylethanol (right column), while the S enantiomer (middle column) is not converted by the enzyme.

Enantioselective hydrolysis of epichlorohydrin with manganese, chromium and Cobalt-salen catalysts

Three times 300 µl of a solution containing 600 µmol of the catalysts (S, S) -M-Salen (a: M = Mn; b: M = Cr; c: M = Co) in toluene were placed in the wells of the microliter plate pipetted in. Then 78.4 μl (1 mmol) of the epichlorohydrin as racemate, S or R enantiomer were added. Now infrared images of the plate with the solutions for the temperature calibration, the two-point correction of the detector and the offset were taken. The reaction was then started by adding 9.9 μl (0.55 mmol) of water at 27 ° C. and infrared images of the plate with the solutions were taken at various times during the reaction. Fig. 6 shows that the manganese catalyst (a) is not active, the chromium catalyst (b) shows a recognizable reaction only with the S-epichlorohydrin, while the cobalt catalyst (c) is the most active, the S-enantiomer reacts better than the racemate. None of the catalysts showed a recognizable reaction with the R enantiomer.

Hydrolysis of various substrates with a cobalt-salen catalyst

100 .mu.l of a solution containing 2 .mu.mol of the catalyst (S, S) -co-salen in toluene were pipetted into 9 wells of the microliter plate. Then solutions of the epoxides df as racemate, S or R enantiomer were added (df = epoxides of the formula RCHCH ₂ O, d: R = CH2OCH ₂ Ph, e: R = Ph, f: R = CH ₂ Cl) . The solutions contained the epoxides in a concentration of 3.85 mol / l. Before starting the reaction by adding water at 27 ° C, infrared images of the plate with the solutions for the temperature calibration, the two-point correction of the detector and the offset were again taken. After the addition of water, infrared images of the plate with the solutions were taken at various times during the reaction. Fig. 7 shows that the cocatalyst reacts selectively with the S enantiomers of epoxides a and b.

Claims (15)

1. A method for comparative determination of the heat caused by physical or chemical processes, characterized in that the difference image is registered with the help of an IR camera, which is a subtraction of the IR emission registered before the processes from that during the execution of the processes registered IR emission. 2. The method according to claim 1, wherein the chemical processes using chemical reactions carried out by catalysts be, the catalysts as a catalyst library over the area a library plate are arranged. 3. The method according to claim 1, wherein as chemical or physical Processes sorption processes, phase transformations or material transformation lungs on or from materials that are on the surface of a Library plate are arranged. 4. The method of claim 2, wherein the catalyst libraries from Catalyst components in the form of metal oxides and / or mixed metals oxides exist, their precursors as aqueous or alcoholic solutions of silicon or metal compounds in the form of their alkoxy derivatives, mixed alkoxy derivatives, their alkoxyoxo or acetylacetonate derivatives or in the form of their halides or carboxylates over the area of the Library plate, can be arranged, followed by drying and Calcine. 5. The method of claim 4, wherein it is in the catalyst components are carbides, nitrides or zeolites. 6. The method according to claims 2-4, wherein the library plate from one Material with low IR reflectivity exists.   7. The method of claim 6, wherein the slate library plate consists. 8. The method of claims 2-4, wherein the library plate with a film is coated, which has low IR reflectivity. 9. The method according to claims 2-7, wherein the part of the surface of the Library plate that is not covered with catalysts or materials with coated with a non-wetting film. 10. The method of claim 2, wherein the library plate reaction spaces contains in which liquid reaction solutions with homogeneous Catalysts are located. 11. The method according to claim 10, wherein as catalysts enzymes or soluble organometallic compounds are used. 12. The method according to claim 2 or 10, wherein the selectivity or Enantioselectivity determined by catalyzed reactions on libraries becomes. 13. The method according to claims 2 and 4-12, wherein the catalysts under Reaction conditions are in one reactor and from the external arranged IR camera through an IR-transparent window become. 14. The method according to claims 1-13, wherein the IR emission by a wavelength-specific IR filter is registered. 15. The method according to claim 13, wherein surfaces of the reactor interior are coated with a varnish that has low IR reflectivity.