JPH04503027A - catalyst - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] catalyst The present invention relates to catalysts. In particular, the present invention relates to a first layer metal catalyst.

According to the present invention, a catalyst consisting of a reduced first layer metal supported on a carrier. the support and up to about 10% by weight of the first layer of metal; The Group I metal present in the catalyst is determined to be at least about t5rd/g. A group metal surface area is provided.

In measuring the surface area of group Ⅰ metals, the present inventors determined that the adsorbed carbon monoxide Assuming that the area occupied by one molecule of is 16.8X10-”d　C16,8λ3) did.

The inventors have determined that the first layer of metal present in the catalyst is at least about 45 rrr/g. In contrast to the catalysts of the present invention, which are characterized by a surface area of Group I metals, The first catalyst supported on a carrier is prepared by conventional pre-reduction techniques from the same catalyst precursor. The layer metal catalyst has much less than about 45 d1 g of first layer metal present in the catalyst. It was found that the metal had no exposed Group I metal surface area.

According to the literature, the catalytic activity of the first layer metal hydrogenation catalyst exists after pre-reduction. It has been suggested that this is due to reduced metal particles. Therefore, as a result, Catalytic activity is more or less directly related to the exposed surface area of the reduced metal. They tend to have a relationship with each other.

Therefore, the greater the surface area of the exposed reduced metal, the greater the activity of the catalyst.

In the limit, the first layer of metal will have the shape of individual metal atoms on the support. Ru.

In a preferred form of the catalyst according to the invention, substantially all of the metal content of the first layer is exists as fine particles of reduced metal.

The catalyst precursor consists of a first layer of metal oxide or salt and a carrier. A suitable precursor is by impregnating the support with a solution of the metal salt of the first layer and then optionally igniting. Obtainable. Co-precipitation can also be used if appropriate. Before suitable catalyst Methods for producing precursors are well known to those skilled in the art of catalyst production. These catalyst precursors The first layer consists of microcrystals of the metal in reducible form dispersed almost uniformly on the support. It is considered that The size of these microcrystals is determined during the preparation of the catalyst precursor. depends on prevailing conditions. The smaller these microcrystals are, the more reduced they are. It can be assumed that the surface area of the metal in the catalyst is large. The method for producing the catalyst precursor is the same as the method for reducing the catalyst used. Affects the final surface area of the first layer of metal in the medium.

The metal in the first layer can be any of the metals traditionally used in the production of carrier-supported catalysts. In particular, those used for producing the first layer metal hydrogenation catalyst may be used. be. Examples include platinum, palladium, rhodium and ruthenium. .

Any suitable carrier can be used, examples include alumina, silicon, etc. Lika-alumina, thoria, silicon carbide, titania, chromia, zirconia, or There is carbon. The content of the first layer metal in the catalyst precursor is from about 0.01% by weight Usually in the range of about 10% by weight, typically about 5% by weight of the catalyst precursor. up to, for example about 0.5% by weight.

The catalyst precursor is typically in the form of a powder with a particle size of no greater than about 100 μm. have a condition. Such powders can be conventionally prepared into any conventional catalyst shape, e.g. round. For cylindrical pellets, rings, saddles, etc., use standard bonding agents and die lubricants. This material can also be used for fixed-bed operations. becomes possible.

The present invention also provides a method for making a catalyst. In the method, supported by a carrier, The metal catalyst precursor in the first layer shows significant pre-reduction of the catalyst in a hydrogen-containing atmosphere. The pre-reduction process is carried out by heating at a detectable pre-reduction temperature. The characteristics there are , before performing this pre-reduction treatment, the catalyst precursor was subjected to the above-mentioned conditions under hydrogen-deficient conditions. Atmosphere consisting of a large amount of inert gas and only a small amount of hydrogen at a temperature below the pre-reduction temperature The catalyst precursor is pre-reduced by soaking during the process. be. Preferably, heating from ambient temperature to the pre-reduction temperature takes place in this atmosphere. It will be done. Hydrogen deficient conditions are maintained throughout the pre-reduction step of the process of the invention. be done. That is, the catalyst precursor is always hungry for hydrogen, and therefore the first layer of metal oxide or The rate of salt reduction is limited by the availability of hydrogen at the catalyst precursor surface. It turns out. In this way, the rate of reduction of the first layer to metal is controlled at a controlled rate. and executed.

This procedure requires heating from ambient temperature to approximately 140°C, as in conventional methods. It is not a 100% hydrogen atmosphere, but a gas containing only a small amount of reducing gas. Such a catalyst precursor in that it is carried out from beginning to end in the presence of a mixture of This differs from the procedure previously recommended by the manufacturer. active phase from the catalyst precursor It is unclear exactly what mechanism is involved in creating a single-layer metal catalyst. is not known. However, this mechanism is dependent on the first layer of metal acid present on the carrier. involves the reduction of at least a portion of the compound or salt to the corresponding first layer metal.

At temperatures below the pre-reduction temperature (typically about 140°C) the catalyst precursor and hydrogen Although no discernible reaction is detected between the contained gas and the metal oxide in the first layer or Some small amount of the salt is actually reduced, thereby reducing the metal source in the first layer. The microscopic nucleation of particles is similar to that produced when camera film is exposed to light. It occurs in the same way as the microscopic nucleation of children. The latent image on exposed film is visible Although not detectable, this is the result of conventional processing by exposure to reducing agents. It can be made visible. In a similar manner, the pre-reduction step of the present invention creates a "latent image" consisting of a large number of microscopic nucleations of metal atoms in the first layer. , these grow individually to form a very large number of first layer metal particles, The resulting first layer metal catalyst has a correspondingly large exposed surface area of the first layer metal. It is thought that the area will become larger in the evening. Conventional pre-reduction techniques are used for this purpose. 180° C. or higher in the presence of a hydrogen-containing gas. If preheating is carried out or the catalyst precursor is inert before it comes into contact with the hydrogen-containing gas. When preheated to a temperature of about 180°C under a gaseous atmosphere, the The first layer of metal atoms formed by nucleation with a relatively low value of Serves as a focal point for the reduction of oxides or salts to metals, resulting in group II metals. relatively large crystallites are formed, thus the exposed surface area of the Group 1 metal is smaller. The catalytic activity in the hydrogenation reaction becomes lower.

Adopting an appropriate temperature one-hour profile, the inflow gas to the pre-reduction zone and the pre-reduction The pre-reduction step or Any reactions involved in the saw kick step are always carried out at the lowest temperature possible. to occur as completely as possible before increasing the temperature again. You can check that it is ready. Also, the exothermic pre-reduction reaction Any heat produced as a result of the reaction is removed by the hydrogen-containing gas and transferred to the catalyst. The risk of thermal damage is minimized.

The method of the invention includes the use of a gas saw kick step. This gas saw kicks In the step, there is no liquid present, but the gas completely penetrates the catalyst precursor. and can be balanced with this.

The gas saw kick step according to the preferred method of the invention includes The precursor is at ambient temperature (e.g., about 15°C to about 25°C, typically about 20°C). At a temperature intermediate to the pre-reduction temperature (typically about 180°C), a hydrogen-containing atmosphere will be maintained. Gas soaking is performed at a temperature below ambient temperature, e.g. 0°C or below. You can also start with: In this gas saw kick step, The hydrogen-containing atmosphere is typically an inert gas such as nitrogen, helium or argon. In addition to hydrogen, only small amounts, typically less than about 1% by volume, preferably 0. Contains only 5% by volume or less. Do not touch the gas saw kick step. The solvent precursor is heated from start to finish in a hydrogen-containing atmosphere from ambient temperature to pre-reduction temperature. heating is preferred, but in other cases heating may be initiated under an inert gas atmosphere. , ambient temperature (if heating is performed from below ambient temperature) or appropriately increased. It is also possible to introduce a hydrogen-containing atmosphere at a temperature (for example, about 40°C to about 50°C). It is. However, the essential feature of the method is that the temperature during the gas saw kick step is The closer the temperature is to the pre-reduction temperature, the more the catalyst precursor is constantly in contact with the hydrogen-containing gas atmosphere. However, it is more important that the catalyst precursor is still hydrogen deficient. That's what it means.

In the gas saw kick step of the preferred method of the invention, the catalyst precursor is a gas hourly space velocity appropriate to the conditions, e.g., from about 500/hour to about 60,007 hours; It is heated from ambient temperature (eg, about 20° C.) in a hydrogen-containing gas stream. hydrogen The containing gas preferably includes a small amount of hydrogen (typically less than about 1% by volume) and a large amount of one or more inert gases such as nitrogen, argon, neon, methane, ethane, butane, or consists of a mixture of two or more of these. In a particularly preferred method, reducing gas is a small amount of hydrogen (preferably less than about 0.5% hydrogen, such as about 0.2% by volume) and a large amount of nitrogen, preferably substantially oxygen-free nitrogen.

The gas saw kick step of the method of the invention can also be carried out at normal or reduced pressure. preferably from about 1 bar to about 20 bar, preferably from about 2 bar to about It is carried out at an elevated pressure in the range of 10 bar.

The partial pressure of hydrogen need not be greater than about 0.01 bar, and the gas saw kick step The value can range from approximately o, ooos bar to approximately o, oos pearl. I can do it.

In particularly preferred methods of the invention, the catalyst precursor is heated from ambient temperature to about 140°C. and heated in a reducing atmosphere containing a small amount of hydrogen.

Preheating of the catalyst precursor from ambient temperature to approximately 140°C is carried out at a controlled rate. It is preferable to do so. Typically this preheating step lasts from about 12 hours to about It takes 48 hours or more, for example 24 hours. The temperature is so can be raised at a substantially linear rate between steps, or approximately stepwise. For example, the temperature can be raised in steps of about 5°C to about 10°C. Ru. In this case, each step is followed by a period of time during which the temperature is maintained substantially constant; Raise the temperature again. Over the range of about 140°C to about 180°C, the catalyst Precursor is maintained under reducing conditions at all times and the inflow and outflow of the pre-reduction zone Heating if the heating is done in such a way that the compositions of the gases are substantially the same as each other. can follow any temperature-hour curve. Preferably the temperature is about 140 °C to approximately 180 °C in an approximately linear manner. According to an example of the procedure , the heating is carried out in a series of steps, the temperature being approximately 10°C, and the predetermined A careful check of the composition of the inlet and outlet gases to the reduction zone is carried out at the end of each heating stage. It is done during and before and after. Under typical operating conditions, from about 140°C to about 180°C The rate of increase in temperature over a temperature range of °C is about 5 °C/hour to about 5 °C/hour, e.g. The temperature is 10°C/hour.

In this heating step from about 140°C to about 180°C, the gas flow rate is about Hourly gas hourly space velocities from 400/hour to about 6000/hour or more (0°C and 1 (measured in bar), for example approximately corresponds to approximately 3000/hour.

The composition of the hydrogen-containing gas depends on the operating pressure. The higher the total pressure, the maximum The lower the concentration of hydrogen that can be tolerated, the lower the total pressure. The concentration of hydrogen can be increased. Typically the H3 concentration is determined by the preferred operating conditions. from about 0.01% v/v to about 1% v/v, for example about 0.2% v/v It is v.

Once the catalyst precursor reaches a final temperature of approximately 180°C, the partial pressure of hydrogen is gradually increased. It will be done. However, during this catalyst activation phase, the inflow and The composition of the effluent gas should still be closely monitored, and these two compositions are substantially the same at all times.

If desired, further heating to about 210° C. or higher can be carried out. Can be done.

When the catalyst precursor reaches the pre-reduction temperature, there is virtually no excess hydrogen present. , thus the catalyst is damaged due to thermal runaway due to the exothermic catalyst pre-reduction step knob. It is important to ensure that the risk of being exposed is minimized.

Prereduced catalysts prepared in accordance with the teachings of the present invention are likely to contain Group 1 metal fines. Sensitive to oxidation due to some re-oxidation of the particles. Therefore this pre-reduced catalyst is preferably stored under an inert gas or hydrogen-containing atmosphere after production.

The catalyst of the present invention hydrogenates an unsaturated organic compound to produce at least one of its hydrogenated compounds. It can be used in a wide variety of reactions to obtain products.

The invention is further illustrated by the following examples.

Trap Arashi Takumi Kami Tennobu 1 3.OX3. 0.5% rutheni on alumina support in the form of pellets of 0.0 mm Two samples of PG 88/10 catalyst precursor consisting of NW148Y! Davey Mackie, 68 Hammersmith Road Davey House (available from London) Limited) in each case in the reaction vessel. Filled. The amount of catalyst precursor is in each case between 2.5 g and 2.6 g. Yes, I weighed it carefully. Oxygen-free nitrogen at an outlet pressure of 4.45 bar at room temperature (20°C) with a flow rate of 200 l/h (measured at 0°C and 1 bar) was passed through the reaction vessel for 30 minutes.

At the same total flow rate, hydrogen is added at 0.2% hydrogen in the nitrogen stream. introduced into a nitrogen stream. The temperature of the reaction vessel was gradually increased to 140°C at a rate of 5°C per hour. The flow of 0.2% hydrogen in nitrogen was maintained at the same flow rate.

Incoming and outgoing gases were continuously monitored by thermal conductivity. Next, approximately 24 The hydrogen level in the gas stream was gradually increased to 1% over time. of hydrogen When absorption is no longer detectable, increase the temperature to 160°C at a rate of 15°C per hour. the composition of the incoming gas is the same as that of the outgoing gas, thus absorbing hydrogen. The temperature was maintained until harvest was indicated to be complete. Then the temperature of the catalyst was increased to 2 o'clock. The temperature was raised to 180°C over a period of time. Next, keep the catalyst temperature still at 180℃ While increasing the hydrogen level to 100%, the system condition was maintained for 18 hours. I maintained it. When the hydrogen gas flow reached 100%, the temperature was increased to 200°C. This level was maintained for 1 hour before using the catalyst.

After this reduction procedure, the catalyst is cooled to 20°C in an oxygen-free helium stream. However, the surface of ruthenium is reduced by the reaction with carbon monoxide on the reduced ruthenium surface. The area was measured. -One molecule of carbon oxide is 16.8X1G-"rr? (16, carbon monoxide until the reaction is no longer detectable, assuming that it occupies a surface of 8. By continuously injecting the element into a helium stream, the extent of the reaction can be controlled by The number of carbon monoxide molecules adsorbed on the thenium surface was measured. In this way, the return The area of exposed metallic ruthenium of the recovered catalyst was calculated.

The following adsorption amount and the corresponding metal surface area of ruthenium are recorded in Example 1 and A comparative experiment using the same catalyst precursor used in Example 2 was carried out in the following manner.

Load another 3d sample of catalyst precursor pellets into the reaction vessel for each case. did. This catalyst precursor was placed in a 100% hydrogen stream with an outlet pressure of 4.45 bar. heated to 210°C for 1.5 hours at a gas hourly space velocity of 30,007 hours. and maintained at this temperature for 30 minutes before characterization.

Using the carbon monoxide reaction technique of Examples 1 and 2, the following results were obtained.

Comparing these results, it can be seen that the gas saw kick steps of Examples 1 and 2 Compared to the results obtained for their respective counterparts in Examples A and B, It is shown that this results in increased ruthenium surface area.

Kanuraho 1L standing 1 In these examples, the catalyst sample was in each case Example 1. was loaded into a reaction vessel and processed according to the following steps.

1.0. 4.45 bar of nitrogen without containing gas at room temperature of 18007 hours It passed through the reaction vessel at a space velocity per hour. This hourly gas space velocity is at the beginning of the experiment. It was maintained until the end.

2, 0.2% H8 in N, was flowed over the catalyst for 24 hours at 20°C.

3. Raise the temperature to 140℃ at 5℃ per minute, and simultaneously increase the flow of inflow and outflow gas. When the composition of the incoming and outgoing gases is equal, the H1 content is reduced to 1% over 24 hours. was slowly increased.

5. Raise the temperature to 160°C at 0.25°C per minute and hold at 160'C for 4 hours. After that, the compositions of the incoming and outgoing gases were equal.

6. Slowly increase the H8 content to 5% over 4 hours and reduce the gas flow to this concentration. The temperature was maintained for an additional 4 hours.

7. Raise the temperature to 180°C at 0.25°C per minute and keep at this temperature for an additional 4 hours. It was.

8. The temperature was further increased to 200°C at 0.25°C per minute, then for the next 6 hours. The H1 content was gradually increased to 100% over 8 hours.

9. 100% H3 gas flow was maintained at 200° C. for a minimum of 8 additional hours.

10. Flush the system with 100% N at 20G℃ for subsequent adsorption investigation. It was then cooled to 25° C. under N8.

The catalyst sample was then subjected to monoxidation in a pulsatile mode using the following experimental technique: It was characterized by its irreversible chemisorption ability of carbon.

11. Pure helium at 2 S °C at a gas hourly space velocity of 1800/hr. Flushing was performed.

12. Gas stream flowing through 500 μ2 pulses of 5% carbon monoxide in helium The amount of carbon monoxide injected into the reactor and flowing out from the reaction vessel is measured using a thermal conductivity detector. did. The amount of carbon monoxide in the pulse adsorbed by the catalyst sample was then determined by 50 Area of peak value obtained from standard pulse of 5% carbon monoxide at 0μ2 and after adsorption It was calculated as the difference between the area of the peak value obtained for the effluent.

13. Repeat step 12 until it is clear that adsorption is no longer occurring. did. From the results obtained, the total amount of irreversibly adsorbed carbon monoxide was determined.

The dynamic pulsatile mode of adsorption gives only the amount of irreversibly adsorbed carbon monoxide. Therefore, to determine the metal surface area of the catalyst, the total amount of carbon monoxide adsorbed is It is important to determine the This was demonstrated using the radioactive tracer method at 25°C. 1 “C under static conditions, i.e. at the same temperature used in the dynamic pulsating flow experiments. -Achieved by determining the adsorption contours of carbon oxide. irreversibly adsorbed The carbon monoxide fraction is reversibly removed by flushing the catalyst sample with a helium stream. This is done by measuring the decrease in surface count rate due to the removal of adsorbed species. It was done. For all samples tested, irreversibly adsorbed carbon monoxide The amount represented 50±2% of the total adsorption capacity of the catalyst.

The absolute value of irreversibly adsorbed carbon monoxide is then determined using the dynamic pulsating flow technique described above. From the amount, the surface area of the sieved metal on the reduced catalyst was calculated. in each case Therefore, the total capacity of carbon monoxide adsorption of the catalyst for irreversibly adsorbed carbon monoxide is Assumed to be 50% of the force. As confirmed by infrared spectrum, Assuming that carbon oxide is adsorbed linearly, and one molecule of adsorbed carbon monoxide Assuming that the area is 16.8xlO-”n? (16,8 people 8), the metal The total surface area was calculated.

0.5% Ruthenium Catalyst Precursor on Alumina Support from Two Different Batches Four parts of the body P088/10 were used in Examples 3 to 6.

These batches are distinguished as Samples A and B. 2 used in Examples 3 and 5 two portions are in unreduced form from samples A and B, respectively; The two parts used in Examples 4 and 6 were from samples A and B, respectively. However, it has been exposed to the air after being treated according to conventional pre-reduction techniques. Ru. The results obtained are shown in Table 3 below.

A run that is identical apart from the fact that the catalyst of Example 4 is already prereduced. Comparison of the results of Examples 3 and 4 shows that the method of the invention where the first reduction step is carried out has an important influence on the exposed metal surface area in the reduced catalyst. It is observed that. That is, conventional pre-reduction is probably due to the reducible This leads to some agglomeration of the ruthenium-containing microcrystals, whereas the method of the present invention No such agglomeration occurs. The catalyst of Example 6 was subjected to a conventional pre-reduction step. Similar results were observed from Examples 5 and 6, which are identical apart from the fact that be done. (Examples 3 and 5 illustrate catalysts within the scope of the present invention; Examples 4 and 6 are not. ) Comparative examples C to G In this comparative example, further portions of catalyst samples A and B were added to the reaction mixture of Example 1. The treatment was carried out by pre-reduction according to conventional techniques in a reaction vessel.

This form of pre-reduction consisted of the following steps.

1, 4.45 bar hydrogen at 25° at a gas hourly space velocity of 1800/hour C through the reaction vessel.

2. Raise the temperature to 200°C at a rate of 10°C per minute while maintaining the hydrogen flow rate. I let it happen.

3. The catalyst was maintained under these conditions for a minimum of 11 hours.

4. Flush the reaction vessel with 100% N at 200°C and remove this N2 flow. The mixture was cooled to 25° C. while maintaining the temperature.

5. Then, using the CO adsorption method described in Examples 3 to 6, the surface of the metal was Accumulated.

The results obtained are shown in Table 4 below.

In contrast to the results of Examples 3 to 6, the conventional pre-reduction techniques of these comparative examples The surface area of the metal measured after treatment is the same for unreduced and pre-reduced samples. It is noteworthy that there was no significant change between the two. On the other hand, Example 3? Using the method of the present invention shown in et al. The metal surface area is almost double that from the pre-reduced sample.

Takumi Kanwata The following catalyst samples were treated according to the general procedure set forth in Examples 3 to 6. Similar good results were obtained.

0.1% platinum on alumina support 0.1% rhodium on alumina support 0.1% palladium on alumina support 0.1% ruthenium on carbon support 0.1% platinum on carbon support 0.1% rhodium on carbon support 0.1% palladium on carbon support international search report 1-Ichimoichi-14shi Cao-em-^・Gang 1-Raiφya 1PCT/GB901001 30 International Search Report

Claims (17)

[Claims] 1. a support, up to about 10% by weight of a Group VIII metal, and a monoacid on the catalyst. The Group VIII metal present in the catalyst as determined by carbon adsorption is at least A support characterized in that it has a Group VIII metal surface area of about 45 m2/gram. Catalyst consisting of a Group VIII metal supported, promoted and reduced. 2. Group VIII in which substantially all of the Group VIII metal content in the catalyst has been reduced 2. The catalyst of claim 1, wherein the catalyst is present as fine metal particles. 3. 3. A catalyst according to claim 1 or 2, wherein the Group VIII metal comprises ruthenium. 4. A catalyst according to any one of claims 1 to 4, wherein the support is alumina. 5. in a hydrogen-containing atmosphere at a pre-reduction temperature where significant pre-reduction of the catalyst is detectable. The Group VIII metal catalyst precursor supported on the carrier is pre-reduced by heating. 2. A method for producing a catalyst for treating a hydrogen-deficient catalyst prior to performing the pre-reduction treatment. The catalyst precursor is heated under lean conditions with a large amount of inert gas at a temperature below the pre-reduction temperature. catalyst precursor by soaking in an atmosphere consisting of hydrogen and only a small amount of hydrogen. A method characterized by performing a pre-reduction process. 6. Heating from ambient temperature to said pre-reduction temperature is carried out in a hydrogen-containing atmosphere. Method of Section 5. 7. 7. The method of claim 5 or 6, wherein the pre-reduction temperature is about 140<0>C. 8. The catalyst precursor is placed in a hydrogen-containing atmosphere at a temperature intermediate between ambient and pre-reduction temperatures. 8. The method of any one of claims 5 to 7, wherein: 9. Under controlled conditions, the catalyst precursor contains only a small amount of hydrogen and a large amount of one or more inerts. claims heated from ambient temperature in a hydrogen-containing gas stream consisting of a mixture of gases; Any one method from items 5 to 8. 10. The hydrogen-containing gas is essentially oxygen-free and consists of a small amount of hydrogen and a large amount of nitrogen. 10. The method of claim 9, which is a mixture. 11. The soaking step is carried out at a pressure ranging from about 2 bar to about 10 bar. 11. The method of any one of claims 5 to 10. 12. The partial pressure of hydrogen during the soaking step is from about 0.0005 bar The method according to any one of claims 5 to 11, in the range up to about 0.0005 bar. . 13. The catalyst precursor is heated from ambient temperature to about 14°C in an atmosphere containing a small amount of hydrogen. 13. A method as claimed in any one of claims 5 to 12, characterized in that it is heated at a controlled rate to 0<0>C. 14. The catalyst precursor is maintained under reducing conditions at all times and there is no flow into the pre-reduction zone. Temperature hourly curves of heating rates such that the compositions of the gases and the effluent gas are substantially the same The catalyst precursor is heated over a temperature range of about 140°C to about 180°C. 14. The method of any one of claims 5 to 13, wherein the method is heated. 15. Gas flow rate when heating the catalyst precursor from about 120°C to about 170°C is about 400/h to about 6000/h gas hourly space velocity (at 0°C and 1 bar) 15. The method according to any one of claims 5 to 14, corresponding to (measurement). 16. Any one of claims 5 to 15, wherein the catalyst precursor contains ruthenium. Law. 17. 17. A method according to any one of claims 5 to 16, wherein the support is alumina.