WO2007104290A1

WO2007104290A1 - Reactor for heterogeneous gas phase reactions, apparatus for testing catalysts for heterogeneous gas phase reactions, and method for testing such catalysts

Info

Publication number: WO2007104290A1
Application number: PCT/DE2007/000446
Authority: WO
Inventors: Marcus Bonifer; Martin Lucas; Peter Claus
Original assignee: Technische Universität Darmstadt
Priority date: 2006-03-13
Filing date: 2007-03-12
Publication date: 2007-09-20
Also published as: DE102006011822A1; DE102006011822B4

Abstract

The invention relates to a reactor for carrying out heterogeneous gas phase reactions or testing catalysts for heterogeneous gas phase reactions. Said reactor comprises at least one reactor vessel that is provided with an inlet end and an outlet end, at least one receiving device for a catalyst, at least one inlet port for gas that is to be reacted in the area of the inlet end, and at least one discharge port for reacted gas in the area of the outlet end. The inventive reactor further comprises at least two units for cooling the reactor vessel, each of which is in thermal contact with the reactor vessel at least in the section in which the receiving device for the catalyst is located in the reactor vessel, and at least one, especially at least two units for heating the reactor vessel, each of which is in thermal contact with the reactor vessel at least in the section in which the receiving device for the catalyst is located in the reaction vessel. The cooling units and heating units are arranged such that the reactor vessel can be heated or cooled particularly in a substantially homogeneous manner, at least in the area of the receiving device for the catalyst. The invention also relates to an apparatus for testing catalysts for heterogeneous gas phase reactions. Said apparatus encompasses at least one inventive reactor, at least one gas supply pipe to the reactor, at least one product gas discharge pipe out of the reactor, at least one analysis unit that is effectively connected to the product gas discharge pipe, and an evaluation unit which is effectively connected to the analysis unit.

Description

Reactor for heterogeneous gas phase reactions, apparatus for testing catalysts for heterogeneous gas phase reactions and methods for testing such catalysts

Beschreibunfi

The present invention relates to a reactor for carrying out heterogeneous gas phase reactions and to testing catalysts for heterogeneous gas phase reactions and to a method and apparatus for testing catalysts for heterogeneous gas phase reactions.

Although known for a long time, heterogeneous gas phase reactions are still becoming more important, not least because of the very cost-effective use of the catalyst material. Its reusability is just as important here as the generally unproblematic handling of reactants and products. For heterogeneous gas phase reactions, both reduction catalysts, for example in the selective reduction of hydroxyl groups or the partial hydrogenation of double bonds, as well as oxidation catalysts, such as, for example, in motor vehicles as catalytic converters into consideration. With the help of such catalytic converters, for example, sulfur-containing residues, carbon monoxide, polycyclic aromatic compounds, nitrogen oxides and soot particles should be removed. For example, in SCR (Selective Catalytic Reduction) technology, nitrogen oxides on a suitable catalyst are reduced to nitrogen in the presence of ammonia. SCR catalysts are generally based on one element from the group Pt, Pd, Rh, Ir, Au, Ag and Ru. For the continuous regeneration of particulate filters, the so-called CRT process (continuous regeneration trap), as described in DE 199 55 124 Al and DE 103 21 105 Al, recourse. In this case, the particle filter is preceded by an oxidation catalytic converter in the exhaust gas line which supplies the nitrogen oxide contained in the exhaust gas Oxidized nitrogen dioxide, which is then used for the oxidation of carbon monoxide or carbon black.

To get to a suitable for mass production catalytic converter, usually numerous test series and optimization cycles are required. The cost of such series of tests is further increased by the fact that the catalysts to be tested are generally applied to a suitable monolith and find out the optimum reaction temperature for each individual catalyst composition. A characteristic parameter for catalytic converters is the so-called light-off temperature. This is the catalyst temperature at which it reaches 50% of its nominal conversion rate.

DE 102 54 477 B3 proposes a test method for determining the functionality of an exhaust gas catalyst, which allows to dispense with a separate temperature sensor, without in this case the fuel consumption is significantly increased. The test device used for this purpose is still very expensive and requires, for example, an injection system for test injection of a predetermined amount of fuel during an expansion stroke or during an exhaust stroke of the internal combustion engine, an exhaust gas recirculation device, a measuring direction and an evaluation unit.

The method according to DE 103 33 337 Al also makes use of the determination of the light-off temperature in order to measure a catalyst system with a near-engine pre-catalyst and a main catalyst. Here, specific attention is paid to the oxygen storage capacity of the primary and the main catalytic converter.

DE 101 01 118 A1 discloses a very complex method for evaluating the performance of solid catalysts. Afterwards, a high-throughput screening can be achieved by a fast determination of kinetic data in a large number of parallel operated realctors. The concentrations of key reactants and products are measured at the reactor inlet and outlet of each reactor, which are covered with different catalytic materials. In addition, the concentration determinations of the reactants at the reactor outlet are made for different temperatures, residence times, pressures and reactant concentrations at the reactor inlet. In this way, the catalyst performance should predict at different reaction conditions. The method described in DE 101 01 118 Al is very complicated in terms of apparatus and process technology.

US patent application US 2003/0012700 A1 relates to a method for parallel testing of catalyst systems, with particular attention being paid to the arrangement and design of feed valves for the reaction gas. With the device according to US 2003/0012700 A1, a multiplicity of different reactors can be charged in parallel with one and the same uniform reaction gas.

Also, WO 2005/047887 A1 discloses a method and apparatus for testing a variety of catalyst samples. In this case, reactor vessels loaded in a predefined manner are transferred serially from a storage zone into a reaction zone in which the reaction vessel is heated at a predetermined rate.

US 4,099,923 discloses an apparatus for automatically screening a variety of catalyst systems. This device requires a large number of reactor units, heating modules, Gaszuführemrichtungen and analysis and control units.

It would be desirable to be able to use devices for testing a variety of catalysts that do not suffer from the disadvantages of the prior art. It is an object of the present invention to provide a device for testing catalysts that is simple in terms of apparatus, with which short repetition cycles can be realized which allow a direct and timely analysis of the reaction products and with characteristic parameters such as the light-off Temperature can be determined with high accuracy even at high sample throughput. A further object of the invention was to provide reactors for such devices.

The object underlying the invention is achieved by a reactor for carrying out heterogeneous gas phase reactions or for testing catalysts for heterogeneous gas phase reactions, comprising at least one reactor vessel having an inlet end and an outlet end containing at least one receiving device for a catalyst, at least an inlet opening for gas to be converted in the region of the inlet end and at least one outlet opening for reacted gas in the region of the outlet end, at least two units for cooling the reactor vessel, which are present in thermal conditions at least in the section in which the reactor vessel contains the receiving device for the catalyst Are in contact with the reactor vessel, and at least one, in particular at least two units for heating the reactor vessel, which are in thermal contact with the reactor vessel at least in the section in which there is in the reactor vessel the receiving device for the catalyst, wherein the cooling and heating units are arranged in such a way that the reactor vessel, at least in the region of the receiving device for the catalyst, in particular substantially homogeneous, can be heated or cooled.

The reactor vessel may be, for example, a pipe, but may also take any suitable vessel form suitable for carrying out a heterogeneous catalytic gas phase reaction. About the inlet end of the reactor vessel can be charged with the catalyst material. Depending on the height of the pressure to be applied during the gas phase reaction, the inlet end can optionally be closed in a sealed manner. For the purposes of the present invention, the outlet end of the reactor should be understood to mean that region which adjoins the reaction zone, ie the region in which the catalyst is present, and into which the product gases are transported after the reaction. Preferably, the exit port of the reactor immediately adjoins the outlet end. In this case, the opening of the outlet end forms the outlet opening. Likewise, in one embodiment, the opening of the inlet end may coincide with the inlet opening. The (gas) Eintrittsöffhung can also be provided at another point of the reactor vessel or inlet end. About the inlet end of the catalyst is fed regularly and removed again. The catalyst receiver is thus preferably present between the inlet and outlet ends of the reactor. Homogeneously heated or cooled in the context of the present invention is intended to comprise a uniform heating or cooling of the reactor or the reactor vessel at least in the region of the Aufhahmevorrichtung without having distinctive temperature levels or jumps.

hi another embodiment, it is provided that the Aufhahmevorrichtung for the catalyst is a gas-permeable pad or a gas-permeable container.

Particularly preferably, the Aufhahmevorrichtung represents a sieve, preferably made of stainless steel, or a porous mat as a gas-permeable pad. In particular catalyst powders can be well registered and recorded. For monoliths, a holding element can be selected as the receiving device. This may for example be in the taper of the interior of the reactor vessel, so that further slippage of the monolith is prevented. In order to keep the expenditure on equipment and apparatus costs as low as possible, the reactor vessel can also be designed in such a way that only miniaturized monoliths can fit into it. As an alternative to a catalyst in powder form, it is also possible to resort to catalyst granules or pellets. The advantage of being able to use catalyst powder with the reactor according to the invention or the device according to the invention described below, besides the possible miniaturization, can be seen in the fact that expensive preparation of monoliths for test experiments can be dispensed with. In monoliths has often proved to be problematic that the catalyst application is uneven. This will, for example, in determining the light-off temperature error limits within the range of +/- 10 ° C associated, whereas with the inventive reactors and devices limits of error in the range +/- 2 ⁰ C and my be accessible.

Preferably, the cooling and / or heating units are in thermal contact therebetween between the inlet end and the outlet end of the reactor vessel.

Advantageously, the cooling unit comprises at least one cavity or a bore with an inlet end and an outlet end for the passage of cooling gas, in particular compressed gas. In general, it is already sufficient, especially against the background of desired miniaturization of the reactor to choose diameter for the cavities or holes, which are in the range of 3 to 15, preferably from 4 to 10 mm. The cavities or bores can also be configured such that a cooling liquid can be introduced or passed through as cooling medium.

The cooling unit according to the present invention is accordingly designed in such a way that it allows the cooling of the reactor vessel or reactor. A cooling module, i. a device with which the cooling of the reactor or reactor vessel is ultimately accomplished, for example, comprise such a cooling unit, in the cavity of which a cooling rod, for example containing liquid nitrogen is present. Preferably, the cooling is brought about by a pressure gas line connected or connectable to the cavity or the bore of the cooling unit. This system of compressed gas line and cooling unit then also represents a cooling module in the sense described above.

Furthermore, it can be provided according to the invention that the heating unit comprises at least one cavity or a bore for receiving at least one heating element. If necessary, this cavity can also be continuous. In general, it is already sufficient, especially against the background of a desired miniaturization of the reactor, to select diameters for the cavities or bores which are in the range from 3 to 15, preferably from 4 to 10 mm.

Suitable heating elements comprise, for example, electrical heating resistors, for example in the form of heating cartridges. Cartridge heaters are advantageously designed so that they are inserted into the cavity of the heating unit substantially in register to ensure optimum heat transfer. With these heating elements, temperatures of for example 1400 ⁰ C can be achieved, of course, even higher temperatures are possible.

A particularly good heating or cooling of the reactor is achieved in that the heating and cooling units are arranged alternately around the reactor vessel. Preferably, the heating and cooling units are present concentrically around the reactor vessel. It has furthermore proved to be advantageous that in each case adjacent heating and cooling units are predominantly not in contact with each other. In this way, even increased cooling and heating rates can be achieved without affecting the homogeneity of the heating or cooling.

In general, this is already sufficient for each adjacent heating and cooling units are separated by material recesses which extend at least partially between the inlet and the outlet end of the reactor vessel.

According to a particularly preferred aspect of the present invention, the reactor further comprises a sheath, which is at least partially spaced from the cooling and heating units and the reactor vessel at least partially, in particular full circumference, surrounds. As a result, the intended cooling and heating effects can be further accelerated. A particularly effective development in this case comprises at least one baffle for diverting the exiting through the outlet end of the cavity of the cooling unit cooling gas through the space between the jacket and the cooling and heating units. For example, if pressurized gas is passed through the cooling unit, this is deflected by the baffle, and then to escape in the opposite direction between the outer wall of the reactor or the heating and / or cooling units and the jacketing. The compressed gas is thus used twice for cooling. Sheath and baffle are preferably connected to each other, in particular sealed, connected or connectable and in one embodiment in one piece.

A further preferred embodiment further comprises at least one feed line for the gas to be reacted to the reactor vessel, which is at least partially in thermal contact with at least one heating unit. Instead of supplying the feed line of the gas to be reacted via a spaced line of the inlet opening of the reactor, in this embodiment, this line is brought into thermal contact with a heating unit, so as to preheat the gas, which again faster heating rates and thus shorter measuring cycles can accomplish. It is advantageous with regard to the precise monitoring of the investigated activity of the catalysts if the reactor further contains at least one first temperature sensor, in particular a first thermocouple, within the reactor vessel. A particularly accurate tracking of the temperature behavior succeeds in particular when the temperature sensor is present in the region of the receiving device of the catalyst, so that the temperature in a catalyst sample can be measured. The accuracy in the tracking of the reactions investigated is increased again by a second, in the wall of the reactor vessel adjacent to the receiving device of the catalyst temperature sensor. The sensor is preferably present in the wall, which is in contact with the catalyst sample or the receiving device. In this way, even more reliable temperature control of an individual reactor can be controlled or regulated. The heat of reaction of a reactive gas mixture can also be recorded very accurately in the case of an exothermic heterogeneous catalytic gas-phase reaction. Such heat of reaction can be detected, for example, for a catalytic oxidation of a carbon monoxide / propane gas mixture at a reactor temperature of about 300 ° C, even if the heat of reaction only have a minimal effect.

According to a further embodiment of the reactor according to the invention, the reactor vessel, the cooling unit (s) and / or the heating unit (s) are made in one piece. Accordingly, e.g. Cooling and heating units, cooling units and reactor vessels, heating units and reactor vessels or cooling units, heating units and reactor vessel made in one piece. The use of one-piece modules provides, in particular in the handling of the reactors, especially when a large number of reactors are used side by side, considerable advantages.

Of particular advantage in this context, such a reactor comprising at least one tempering, which contains at least two units for cooling the reactor vessel and at least one, in particular at least two units for heating the reactor vessel, wherein the tempering at least in the section in which in the reactor vessel, the receiving device for the catalyst is present, is or can be brought into thermal contact with this reactor vessel and wherein the cooling and heating units can be arranged or arranged in such a way that the reactor vessel in the Aufhahmevorrichtung for the catalyst, in particular substantially homogeneous, can be heated or cooled.

The temperature control unit thus contains the cooling and heating units of the reactor in a modular manner. In this case, it is again advantageous if the temperature control unit is essentially in one piece. With regard to the preferred Ausrührungsformen the heating and cooling units of the tempering the above applies here accordingly.

The temperature control unit and the reactor vessel are particularly preferably in one piece.

For example, the catalyst storage device may be readily adapted for catalyst levels in the range of 20 mg to 700 mg. Powdered catalysts are preferably used with the reactor according to the invention. Their amount and / or activity can be controlled, for example, by adding suitable inert bulk materials such as silicon carbide.

In an alternative embodiment, the heating unit may comprise a heating resistor, for example in the form of a heating wire, which surrounds the reactor vessel at least in the region of the catalytic converter and / or the cooling unit (s) at least in the area of the catalyst receiving device. With this design form, the number of cooling units that can be arranged around the reactor vessel can be further increased, whereby shorter measurement cycles become possible.

Preferably, in such a design, e.g. 4, 5 or 6 cooling units adjacent to each other and surround the reactor vessel.

For example, if there are two or more cooling and / or heating units, they are preferably mounted alternately around the reactor vessel. For preferred Realctoren usually already three cooling units and three heating units, which are mounted alternately sufficient. Satisfactory results are of course already achieved with a small number of cooling and / or heating units. Of course, a larger number of cooling or heating units, for example, 4, 5, 6 or 7 such units to the Reactor container, preferably alternately, be attached. By a uniform, in particular alternating, arrangement of cooling and heating units around the reactor vessel around it is ensured that the reactor vessel is substantially homogeneously heated or cooled at least in the region of the Aufhahmevorrichtung for the catalyst.

The object underlying the invention is further achieved by a device comprising at least one inventive reactor, at least one Gaszuführleitung to the reactor, at least one Produktgasabführleitung of the reactor, at least one analysis unit in operative connection with the Produktgasabführleitung and an evaluation unit in operative connection with the analysis unit , In principle, the device according to the invention can be equipped by a multiplicity of reactors according to the invention, for example 2, 3, 4, 5, 6, 7, 8 or more.

The reactors according to the invention are characterized in particular by the fact that very fast heating and cooling rates can be achieved with them. Common heating rates (temperature ramps) are, for example, in the range from 150 to 200 K / min, in particular from 170 to 200 K / min. Consequently, reaction temperatures within the reactor vessel of about 500 ^° C. can be reached in a very short time. Depending on the heating units and heating elements used, of course reactor temperatures in the range of 1000 to 1500 ° C are readily possible. If the reactor according to the invention is heated to very high temperatures, it is advisable not to use air as compressed gas for the cooling, but an inert compressed gas in order to prevent a detonation of the reactor block.

Insofar as very fast heating and Ablcühlgeschwindigkeiten be made possible with the Realctoren invention, one arrives at very short measuring cycles. As a result, a continuous continuous operation of the device according to the invention can be maintained even with a small number of reactors. For example, four or five reactors according to the invention already suffice, after having passed the test of the catalyst located in the fourth or fifth reactor, to re-enter the catalyst present in the first reactor without having to put in additional cooling phases to undergo another test. Of course, with the device according to the invention can also be a single reactor or any reactor after completion of the test by a new reactor containing, for example, a modified amount of catalyst and / or type of catalyst use.

Suitable analysis units include, for example, mass spectrometers, IR spectrometers, gas chromatographs and flame absorption spectrometers.

In a preferred embodiment, the device according to the invention also comprises at least one evaporator unit for feeding steam and / or gaseous organic compounds into the gas feed line. By using an evaporator unit, substances such as water vapor and evaporable hydrocarbons can be introduced into the (educt) gas stream, which can be very realistic catalytic exhaust gas compositions, as they are usually released from internal combustion engines, simulate.

According to a preferred further development, the device according to the invention further comprises a multiple valve, at least one first gas supply line to the multiple valve, at least one second gas supply line from the multiple valve to at least one first reactor, at least one gas discharge line from the first and / or second reactor to the multiple valve and at least one Gas discharge line from the multiple valve to the analysis unit. Preferably, such a device further comprises at least a second gas supply line from the multiple valve to a second reactor. Suitable multiple valves are e.g. 6-, 8-, 10- or 12-way valves.

In an alternative embodiment, this device also contains at least one bypass sample loop, which is operatively connected to the multiple valve. The use of bypass sample loops can be used for calibration for measurements to be made. Thus, for example, the educt gas or a component of the educt gas can be passed through the bypass sample loop in different concentrations before it is fed to the analysis unit. In particular, for the testing of catalytic converters, such a device has proven suitable when using reactant gases containing water or steam, which further comprises a heatable container, in which the multiple valve, possibly the bypass sample loop (s), at least partially to the gas supply the reactor (s), in each case at least sections of the gas supply line (s) to the multiple valve, in each case at least partially the Gasabführleitung (s) from the reactor to the analysis unit, the Gasabführleitung (s) to the multiple valve, optionally the outlet end of the reactor or the Realctoren, and / or in each case at least partially the gas discharge line (s) from the multiple valve to the analysis unit is present or present. In one embodiment, in the heatable container, the multiple valve, at least partially, the gas supply lines to the reactors, the gas supply lines to the multiple valve, the gas discharge lines from the reactors to the multiple valve, and the gas discharge lines from the multiple valve to the analysis unit. By heating all relevant components of the device according to the invention, which are not already heated due to the measurement or heating, condensation of water droplets or, for example, aliphatic or aromatic hydrocarbons can be prevented. As a rule, it is sufficient for this purpose to heat the heatable container to temperatures in the range of about 65 to 90 ° C.

According to a further aspect, devices according to the invention are provided, in which the discharge line of a first reactor is connected or connectable to the inlet opening of a second reactor. It can further be provided that the Gasabführleitung the second reactor is connected to the inlet opening of a third reactor or connectable.

In particular, when it comes to find optimal conditions for series-connected catalysts, as used in catalytic converters for internal combustion engines, the product gas obtained in a reactor of the device according to the invention is passed into the second reactor. This type of product gas conduction can be repeated as often as desired up to the xth reactor, whereupon the final product gas obtained is fed to the analysis unit, directly or via the multiple valve. In order to obtain an even more accurate insight into the behavior of the individual catalysts connected in series, one can of the gas discharge line of the first reactor and / or the gas discharge line of the second reactor or each further in Series connected reactor feed product gas, directly or via the multiple valve, to the analyzer.

In particular, in order to obtain a direct and timely analysis of the product gas obtained, it has proved to be very advantageous to equip the device according to the invention with a unit for dilution of the product gas with a diluent gas upstream of the analysis unit. Suitable diluent gases are inert gases such as argon or nitrogen.

The object underlying the invention is further achieved by a method for determining the activity of catalysts for heterogeneous gas phase reactions using a device according to the invention, comprising the steps:

a) passing a gas to be reacted through a first reactor at a first temperature, in which a first catalyst for a heterogeneous gas phase reaction is present in or on a Aufhahmevorrichtung,

b) determining the temperature of the catalyst,

c) supplying the reacted gas leaving this reactor, in particular via a multi-way valve to an analysis unit,

d) quantitative and / or qualitative determination of individual or all components of the reacted gas,

e) assigning the qualitative and / or quantitative analysis results to the detected catalyst temperature in an evaluation unit and

f) repeating steps a) and e) at different temperatures and / or with a second or further reactor and / or a second and / or further catalyst. Catalysts for heterogeneous gas phase reactions can be tested very quickly and reliably with the device or the method according to the invention, as a result of which a very efficient optimization of the investigated gas phase reaction can be regularly achieved. This is especially true for the testing of catalytic converters. In addition, all other oxidation and reduction catalysts come into question. As an example, reference is made to catalysts for carbon monoxide oxidation, as used in gas masks. Further examples are the hydrogenation of acrolein in the gas phase and the high-temperature oxidation of methane. The optimization of the catalytic combustion of methane provides a particularly impressive example of the effectiveness of the reactors or device according to the invention, but can be tried in a straightforward, (cost) effϊziente way to find suitable catalyst systems already at temperatures in the range of about 1300 ° C initiate catalytic combustion. Usually, the combustion of methane requires temperatures of about 1600 ° C. At these temperatures, however, ignition of the reactor vessel material is often observed.

For example, with the device according to the invention, reaction of carbon monoxide, hydrocarbons, for example propane, nitrogen oxides, hydrogen, sulfur oxides and ammonia can be readily followed. The determination of the respective light-off temperatures is achieved with high accuracy.

The present invention was based on the surprising finding that can be achieved with the reactor according to the invention very fast heating and cooling rates, which in turn very short Wiederholungszyklen be possible. Furthermore, it has surprisingly been found that a very rapid and reliable mass screening is possible with the device according to the invention for testing catalysts already with low expenditure on equipment, for example with a small number of realators. Furthermore, the device according to the invention is suitable for analyzing the reaction products obtained directly and promptly. Finally, even when powdery catalyst samples are used, it is possible to draw very accurately useful conclusions about monolithic catalysts. Further features and advantages of the invention will become apparent from the following description, are explained in the preferred embodiments of the invention by way of example with reference to schematic drawings. Showing:

Figure 1 is a schematic longitudinal sectional view through a reactor according to the invention;

FIG. 2 shows a schematic cross-sectional view through the reactor according to the invention according to FIG. 1;

Figure 3 is a schematic cross-sectional view through an alternative embodiment of a reactor according to the invention;

Figure 4 is a schematic longitudinal sectional view through an alternative embodiment of a reactor according to the invention;

Figure 5 is a schematic longitudinal sectional view through a further alternative

Embodiment of a reactor according to the invention;

Figure 6 is a schematic representation of the device according to the invention;

Figure 7 is a schematic representation of the interconnection of the invention

Realctoren in an embodiment of the inventive device;

Figure 8 is a schematic representation of an alternative embodiment of the

Connection of erfϊndungsgemäßen reactors in an embodiment of the device according to the invention;

Figure 9 is a schematic representation of another alternative embodiment of a

Interconnection of inventive reactors, at least one gas discharge line from the first and / or second reactor to the multiple valve; Figure 10 is a schematic longitudinal sectional view of a dilution device for the product gas;

FIG. 11 shows a temperature profile for a measuring program for a reactor according to the invention of a device according to the invention;

FIG. 12 shows a temperature profile during a measuring cycle with a device according to the invention;

FIG. 13 shows a diagram, obtained by the method according to the invention, for determining the CO light-off temperature; and

FIG. 14 shows a diagrammatic representation of CO light-off temperatures determined with the device according to the invention.

FIG. 1 shows a schematic longitudinal section through a reactor 1 according to the invention. This reactor has an inlet end 2 with an inlet 4 and an outlet 6 with an outlet 8. In the outlet end 6 facing half of the reactor vessel 10, a receiving device 12 is mounted in the form of a stainless steel mesh on which a catalyst sample 14 is present. In the bed of powdered catalyst sample 14, a thermocouple 16 is introduced in order to detect the reaction temperature of the catalyst continuously or punctually.

On the basis of the cross-sectional view of Figure 2 of the illustrated in Figure 1 reactor 1, the alternating arrangement of cooling units 18 and heating units 20 can be seen, which are arranged concentrically around the reactor vessel 10. In the embodiment illustrated in FIG. 2, the cooling and heating units 18, 20 are in the form of a one-piece tempering unit 22, which surrounds the wall of the tube-like reactor vessel 10 with an exact fit. Suitable Realctoren according to the invention can advantageously be highly miniaturized without having to accept sacrifices in the validity of the results obtained. The length of a reactor vessel may be, for example, in the range of 5 to 25 cm. The diameter of such a reactor can, for example, be in the range of 3 to 15 mm, preferably 4 to 10 mm. A preferred embodiment of a reactor 1 according to the invention has a cross-section represented in FIG. The cooling units 18 and heating units 20 are each separated by recesses 24 and accordingly have only adjacent to the wall of the reactor vessel 10 via mutual contact. As a result, the weight or the total mass of the reactor to be heated is further reduced, which again involves shortened heating and cooling phases. In the cavities 28 of the heating units 20, for example, heating cartridges to form a heating module 30 can be inserted. By dimensioning the heating cartridges as small as possible, the heating unit 20 can be made smaller. Even with this measure, the heating and cooling behavior of the reactor can be further improved.

The cooling rate when using cooling gas can be achieved by pre-cooling the compressed air or the compressed gas, for. B. by means of cryostats, and / or by increasing the gas or air pressure can be increased again. For example, the reactor according to the invention can easily be cooled from 500 ^° C. to room temperature in 20 minutes.

The cooling units 18 are preferably provided with a continuous cavity 26 for passing compressed air or compressed gas for cooling. As well as for the heating unit 20, it is preferable for the cooling unit 18 to use a good heat-conductive material which surrounds the respective cavities and is in contact with the reactor vessel 10.

FIG. 4 shows a preferred embodiment of a reactor 1 according to the invention. In this case, the cooling and heating units 18 and 20 surrounding the reactor vessel 10 can in turn, however, be spaced apart from one another by a jacket 32. This jacket 32 is preferably provided with a baffle 34 adjacent to that end of the cooling unit 18 or cooling units, from which emerges the pressurized gas or compressed air used for cooling. In particular, when the baffle is tightly connected to the reactor vessel 10 and the outlet end 6, a particularly effective redirecting the cooling gas, which is guided past the outer walls of cooling and heating units 18, 20 and this additionally cools. The pressurized gas or compressed air then escapes advantageously over a region opposite the outlet end. The described compressed air guide is again particularly clearly apparent from the schematic Längsschntittsansicht a reactor according to the invention according to Figure 5. The compressed air is passed through the continuous cavity 26 of the cooling unit 18 and deflected at the baffle 34 in the region of the outlet end of the reactor 1. This preferred embodiment of a reactor according to the invention also has a feed line 36 for the gas to be reacted to the inlet opening 38 in the region of the inlet end 2. This feed line 36 is guided along a heating unit 20 in thermal contact therewith. In this way, the gas to be reacted can be introduced preheated into the reactor vessel 10.

FIG. 6 shows a schematic system diagram of a device 40 according to the invention. The device 40 comprises five reactors 1 according to the invention (R1, R2, R3, R4 and R5), as described above, which can all be cooled with compressed air. Via a suitable, in particular variable, gas supply 42, for example by means of MFCs, the gas or gas mixture to be reacted is made available. This gas to be reacted can be supplied to the respective reactors 1 by means of a gas supply line 46 either directly or, as shown, via a multiple valve 44. From the multiple valve 44, e.g. a 12-way valve, go from each gas supply lines 64 to the inlet openings of the respective reactors 1. Accordingly, gas discharge lines 48 lead from the outlet openings 8 of the reactors 1 again to the multiple valve 44. Via a further discharge line 50, the reacted gas or gas mixture passes from the multiple valve 44 to the analysis unit 52.

Furthermore, an evaporator unit 54 can be provided, via which, for example, steam or gaseous hydrocarbons are fed into the gas originating from the gas supply 42 before it is fed to the reactors 1. The evaporator 54 may be e.g. be supplied with water with an LFC. In order to prevent any condensation of liquid, such as water, one sees, as shown in Figure 6, a heatable container 56, in which the multiple valve 44 and the supply lines 46 and 64 and the discharge lines 48 and 50, in each case at least in sections, as well the Bypaßschlaufen present.

In the device 40 according to the invention reproduced in FIG. 6, all 5 reactors 1 can be actuated sequentially via the multiple valve 44. Of course, it is also possible, as shown in Figure 7, the discharge line 58 of the first reactor first (Rl) to enter the inlet opening 4 of another reactor 1 (R3). Only after the product gas of the reactor Rl has also been subjected to a heterogeneous catalytic reaction in the reactor R3, the latter is fed via the discharge line 48, either via the multiple valve or directly, the analysis unit 52. Alternatively, at least a portion of the product gas originating from the reactor R1 may be supplied to the analysis unit 52. Based on the (intermediate) results obtained in this way, it is possible to intervene in the temperature regulation of the downstream reactor R3 via a system control or control unit belonging in one embodiment to the device according to the invention. The analysis results obtained can thus have a direct influence on the heating control or temperature ramps of individual or all reactors. In this way, catalytic converters can be simulated and optimized without any problems. For example, in a first reactor, there may be a catalyst that oxidizes NO to NO ₂ . The resulting NO ₂ is then used to oxidize hydrocarbons to carbon dioxide with the aid of a second catalyst. At the same time, the NO _{2 is} reduced to NO. Finally, the reactive NO is oxidized to NO ₂ using a third catalyst.

As can be seen from FIGS. 8 and 9, the device according to the invention opens up manifold possible combinations in order to connect the reactors 1 according to the invention to one another in series or in parallel.

FIG. 10 shows a dilution device 62 with which the product gas withdrawn from a reactor is diluted before being fed to the analysis unit. As a diluent gas, for example, nitrogen comes into question. By providing a dilution device in the device 40 according to the invention, the product gas can be supplied to the analysis unit, eg an FT-IR device, without loss of time. For example, as miniaturization of the device according to the invention progresses, a volume flow required for the analysis unit can only be achieved by dilution. In addition, condensation of liquids, for example water, or the reaction of nitrogen oxides can be suppressed by way of dilution of the product gas. Thus, the volume flow with the inventive dilution device can easily be diluted 10-fold. 11 shows a temperature / concentration profile for two reactors 1 according to the invention of a device 40 according to the invention. In addition to the two reactors 1, the embodiment of a device according to the present invention has been equipped with a bypass loop 60 via which a control unit is used containing appropriate control software, different concentrations of educt gas were adjusted for calibration. Preferably, towards the end of the bypass phase, the composition of the reaction gas to be tested is set. After switching the multiple valve from the bypass loop to the first reactor, the heating of the reactor has been awaited for a short time in order to achieve a uniform distribution of the reaction gas in the container. The temperature ramp was then started starting from an initial temperature of 70 ° C (first temperature) in the reactor vessel in the range of 150 K / min. As can be seen from FIG. 11, the reaction gas carbon monoxide was completely converted via the oxidation catalyst present in the reactor vessel. Subsequently, a bypass sample loop can again be approached via the multiple valve in order to carry out a renewed calibration in preparation for the measurement cycle in the second reactor. During these phases, the temperature of the first reactor is cooled down within a few minutes by means of cooling gas as described above.

FIG. 12 shows a temperature / time diagram for a device according to the invention, comprising a total of four reactors according to the invention. These reactors are started up sequentially, i. heated with a very high heating rate and then cooled again using compressed air. This cooling process is so rapid for all reactors that, as well as the measuring cycle for the fourth reactor is completed in sequential operation, the first reactor has reached its initial temperature again and for a new measuring cycle, i. a new heating phase is available.

FIG. 13 shows a result of the conversion of carbon monoxide over time with the aid of an analysis unit of a device according to the invention as the temperature in a reactor according to the invention is increased. On the basis of determined at different times carbon monoxide concentrations can easily determine the light-off temperature. Finally, FIG. 14 shows the result of light-off temperature measurements of catalyst systems of the same type present in five reactors. These are averages obtained from a variety of repeat measurements taken over a long period of time. As can be seen from the figure, the light-off temperature measurement was carried out twice in total. Every single measurement included a large number of repetitive cycles. As the diagram analysis shows, the tests carried out provide reproducible results.

The features of the invention disclosed in the foregoing description, in the drawings and in the claims may be essential in any combination for the realization of the invention in its various embodiments.

LIST OF REFERENCE NUMBERS

reactor

inlet end

inlet opening

outlet

outlet opening

reactor vessel

Catcher for the catalyst

catalyst sample

temperature sensor

cooling unit

heating unit

tempering

Cavity of the cooling unit

continuous cavity

Cavity of the heating unit

heating module

jacket

baffle

Supply line for reaction gas

inlet opening Device for testing the activity of catalysts

gas supply

Multiple valve

gas supply

gas discharge line

analysis unit

Evaporation unit

heated container

discharge

Bypass sample loop

diluter

gas supply

Claims

claims

A reactor (1) for carrying out heterogeneous gas phase reactions or for testing catalysts for heterogeneous gas phase reactions, comprising

- At least one reactor vessel (10) having an inlet end (2) and an outlet end (6) containing at least one Aufhahmevorrichrung (12) for a catalyst, at least one inlet opening (4) for reacted gas in the region of the inlet end (2) and at least one At least two units for cooling (18) the reactor vessel, which at least in the section in which in the reactor vessel (10) the receiving device (12) for the catalyst, each in thermal contact with the reactor vessel (10), and at least one, in particular at least two units for heating (20) the reactor vessel (10), at least in the section in which in the reactor vessel (10) the receiving device (12). is present for the catalyst, each in thermal contact with the reactor vessel (10), wherein the cooling and heating units (18, 20) are arranged in the manner, d the reactor vessel (10) at least in the region of the Aufhahmevorrichtung (12) for the catalyst, in particular substantially homogeneous, can be heated or cooled.

2. reactor (1) for heterogeneous gas phase reactions according to claim 1, characterized in that the reactor vessel (10) is a tube.

3. Reactor (1) according to claim 1 or 2, characterized in that the receiving device (12) for the catalyst is a gas-permeable pad or a gas-permeable container.

4. Reactor (1) according to claim 3, characterized in that the gas-permeable support (12) a sieve, preferably made of stainless steel, or a porous mat, in particular for a catalyst powder, or a holding element, in particular for a monolith.

5. Reactor (1) according to one of the preceding claims, characterized in that the cooling and / or heating units (18, 20) between the inlet end (2) and the outlet end (6) of the reactor vessel (10) in thermal contact therewith available.

6. Reactor (1) according to any one of the preceding claims, characterized in that the cooling unit (18) comprises at least one cavity (24) having an inlet end and an outlet end for the passage of cooling gas, in particular compressed gas.

7. Reactor (1) according to claim 6, further comprising at least one with the cavity (24) of the cooling unit (18) connected or connectable compressed gas line.

8. Reactor (1) according to one of the preceding claims, characterized in that the heating unit (20) comprises at least one cavity (28) for receiving at least one heating element.

9. Reactor (1) according to one of the preceding claims, characterized in that the heating and cooling units (18, 20) are arranged alternately around the reactor vessel (10).

10. Reactor (1) according to one of the preceding claims, characterized in that in each case adjacent heating and cooling units (18, 20) are predominantly not in contact with each other.

11. Reactor (1) according to one of the preceding claims, characterized in that in each case adjacent heating and cooling units (18, 20) through material recesses which at least partially between the inlet and the outlet end (2, 6) of the reactor vessel (10 ) are separated.

12. Reactor (1) according to one of the preceding claims, further comprising a sheath (32) which is at least partially spaced from the cooling and heating units (18, 20) and at least partially, in particular full circumference surrounds the reactor vessel (10) ,

13. A reactor (1) according to claim 12, further comprising at least one baffle (34) for diverting the refrigerant gas exiting through the outlet end of the cavity (24) of the cooling unit (18) through the space between the jacket (32) and the cooling and / or or heating units (18, 20).

14. Reactor (1) according to one of the preceding claims, further comprising at least one feed line (36) for the gas to be reacted to the reactor vessel (10), which is at least partially in thermal contact with at least one heating unit (20).

15. Reactor (1) according to one of the preceding claims, further comprising at least one first temperature sensor (16), in particular a first thermocouple, within the reactor vessel (10).

16. Reactor (1) according to claim 15, characterized in that the temperature sensor (16) in the region of the Aumahmevorrichtung (12) of the catalyst is present, so that the temperature in a catalyst sample is measurable.

17. Reactor (1) according to one of the preceding claims, further comprising at least one second temperature sensor, in particular a second thermocouple.

18. Reactor (1) according to claim 17, characterized in that the second temperature sensor in the wall of the reactor vessel (10) adjacent to the Aumahmevorrichtung (12) of the catalyst is present.

19. Reactor (1) according to one of the preceding claims, characterized in that the reactor vessel (10), the cooling unit (18) and / or the heating unit (20) are integral.

20. Reactor (1) according to one of the preceding claims, comprising at least one tempering unit (22), comprising at least two units for cooling (18) of the reactor vessel (10) and at least two units for heating (20) of the reactor vessel, wherein the tempering ( 22) is or can be brought into thermal contact with said reactor vessel (10) at least in the section in which the catalytic converter (12) is present in the reactor vessel (10), and wherein the cooling and heating units (18, 20) can be arranged or arranged in such a way that the reactor vessel (10) in the region of the Aufhahmevorrichtung (12) for the catalyst, in particular substantially homogeneous, can be heated or cooled.

21. Reactor (1) according to claim 20, characterized in that the cooling unit (18) comprises at least one cavity (24, 26) having an inlet end and an outlet end for the passage of cooling gas.

22, reactor (1) according to claim 21, further comprising at least one with the cavity (24, 26) of the cooling unit (18) connected or connectable compressed gas line.

23. Reactor (1) according to any one of claims 20 to 22, characterized in that the heating unit (20) comprises at least one cavity (28) for receiving at least one heating element.

24. Reactor (1) according to any one of claims 20 to 23, characterized in that the heating and cooling units (18, 20) are arranged alternately in the temperature control unit (22).

25. Reactor (1) according to any one of claims 20 to 24, characterized in that each adjacent heating and cooling units (18, 20) are predominantly not in direct contact with each other.

26. Reactor (1) according to any one of claims 20 to 25, characterized in that each adjacent heating and cooling units (18, 20) through material recesses, the extending at least partially between the inlet and the outlet end (2, 6) of the reactor vessel (10) are separated.

27. Reactor (1) according to any one of claims 20 to 26, characterized in that the temperature control unit (22) is substantially in one piece.

28. Reactor (1) according to any one of claims 20 to 26, characterized in that the temperature control unit (22) and the reactor vessel (10) are substantially in one piece.

29. Reactor (1) according to one of the preceding claims, characterized in that the Aufhahmevorrichtung (12) is designed for the catalyst to receive a quantity of catalyst in the range of 20 mg to 700 mg.

30. Reactor (1) according to one of the preceding claims, characterized in that the cooling and heating units (18, 20) are mounted substantially concentrically around the reactor vessel.

A reactor (1) according to any one of the preceding claims, further comprising a catalyst bed or a catalyst monolith on the receiver.

32. Reactor (1) according to one of the preceding claims, characterized in that the heating unit (20) comprises a heating resistor.

33. Reactor (1) according to claim 32, characterized in that the heating resistor the reactor vessel (10) at least in the region of the Aufhahmevorrichtung (12) for the catalyst and / or the / the cooling units (18) at least in the region of the receiving device (12). surrounds for the catalyst.

34. Apparatus (40) for testing catalysts for heterogeneous gas phase reactions, comprising at least one reactor (1) according to one of the preceding claims, at least a gas supply line (46) to the reactor (1), at least one product gas discharge line (48) from the reactor (1), at least one analysis unit (52) in operative connection with the product gas discharge line (48) and an evaluation unit in operative communication with the analysis unit (52) ,

35. Device (40) according to claim 34, further comprising a control and / or regulating unit.

36. Apparatus (40) according to claim 34 or 35, further comprising an evaporator unit (54) for feeding in steam and / or for feeding gaseous organic compounds into the gas supply line (46).

37. Apparatus (40) according to any one of claims 34 to 36, further comprising a multiple valve (44), at least one first gas supply line (46) to the multiple valve (44), at least one second gas supply line (64) from the multiple valve (44) at least one first reactor (1), at least one gas discharge line (48) from the first and / or second reactor (1) to the multiple valve (44) and at least one gas discharge line (50) from the multiple valve (44) to the analysis unit (52) ,

38. The apparatus of claim 37 further comprising at least one second or nth gas supply line (64) from the multiple valve (44) to a second or nth reactor

(1).

39. The apparatus (40) of claim 37 or 38, further comprising at least one bypass sample loop (60) operatively connected to the multiple valve (44).

40. Apparatus (40) according to any one of claims 34 to 39, further comprising a heatable container (56), in which the multiple valve (44), the bypass sample loop (s) (60), in each case at least partially the gas supply line (64). to the reactor (s) (1), the gas supply line (s) (46) to the multiple valve (44), the gas discharge line (s) from the reactor (1) to the analysis unit (52), the gas discharge line (s) (48) to the multiple valve (44), the gas discharge line (s) (50) of the multiple valve (44) to the analysis unit (52) and / or the outlet end (6) of the reactor or the reactors (1) is present or present.

41. Device (40) according to any one of claims 34 to 40, characterized in that the discharge line (58) of a first reactor (1) with the inlet opening (4) of a second reactor (1) is connected or connectable.

42. Device (40) according to claim 41, characterized in that the Gasabführleitung (58) of the second reactor or a n'ten reactor with the inlet opening of a third or (n + l) 'th reactor is connected or connectable.

43. Device (40) according to claim 41 or 42, characterized in that from the Gasabführleitung the first reactor and / or the gas discharge line of the second reactor product gas via a, in particular controllable, branch line, directly or via the multiple valve, the analysis unit can be fed.

The apparatus (40) of any one of claims 34 to 43, further comprising means (62) for diluting the product gas with a diluent gas upstream of the analysis unit (52).

45. Use of the device according to one of claims 34 to 44 for testing the activity of catalysts for heterogeneous gas phase reactions.

46. Use of the device according to one of claims 34 to 44 for testing the, in particular temperature-dependent, activity of exhaust gas catalysts for internal combustion engines.

47. Use according to claim 46, wherein the device according to claims 34 to 44 determines the light-off temperature.

48. A method for determining the activity of catalysts for heterogeneous gas phase reactions using a device according to one of claims 34 to 44, comprising the steps: a) passing a gas to be reacted through a first reactor at a first temperature in which a first catalyst for a heterogeneous gas phase reaction is present on a Aufhahmevorrichtung, b) determining the temperature of the catalyst, c) supplying the reacted gas leaving this reactor, in particular via a multi-way valve, to an analysis unit, d) quantitative and / or qualitative determination of individual or all components of the reacted gas, e) assignment of the qualitative and / or quantitative analysis results to the detected catalyst temperature in an evaluation unit and f) repeating the steps a) to e) at different temperatures and / or with a second or further reactor and / or a second and / or further catalyst.

49. The method according to claim 48, characterized in that the temperature of the reactor at a rate in the range of 100 K / min, to 200 K / min., Preferably, starting at the first temperature, is increased.

50. The method of claim 48 or 49, characterized in that the first reactor leaving the reacted gas is completely or partially fed to a second reactor or n'ten reactor.

51. The process according to claim 50, characterized in that the reacted gas leaving the second reactor or the nth reactor is supplied wholly or partly to a third reactor and / or (n + 1) th reactor.

52. The method of claim 50 or 51, characterized in that the heating rates for the first, second, third and / or n'ten reactor are different.

53. Use of the device according to one of claims 34 to 44 for analyzing the activity and / or selectivity of catalysts for heterogeneous gas phase reaction, in particular in the partial oxidation or in the selective hydrogenation.