MXPA06009531A - Supported catalyst comprising delta- or theta-modified aluminium oxide supports - Google Patents

Abstract

The invention relates to a method for producing a supported catalyst, consisting of at least 75 wt.%Al2O3, whose delta- or theta-modified fraction of Al2O3 is at least 1%of the total Al2O3 fraction and which contains a rhenium compound and optionally a promoter as the active component (A). According to the invention:a) a modified support (T) is produced from a conventional support (T) consisting of at least 75 wt.%of Al2O3, to which a promoter is optionally applied, the delta- or theta-modified fraction of the Al2O3 being at least 1%of the total Al2O3 fraction, by the calcination of the conventional support (T) at a temperature of between 750 and 1100°C;b) a supported catalyst precursor is produced from the modified support (T) by the application of the active component comprising the rhenium compound (A) to the modified support (T);and c) the supported catalyst precursor is calcinated at a temperature of between 500 and 750°C.

Description

CATALYST WITH ALUMINUM OXIDE SUPPORT WITH MODIFICATIONS DELTA OR TETA The present invention relates to a supported catalyst, the processes for producing it and the processes for the metathesis of the non-aromatic hydrocarbon unsaturated compounds using the supported catalyst.

The metathesis of unsaturated, non-aromatic hydrocarbon compounds is a long established method for breaking and reforming C-C bonds (see Mol, J. C, Chapter 4.12.2"Alkene Metathesis" in "Handbook of Heterogeneous Catalysis", Eds. Ertl, G., Kndzinger, H., Weitkamp, J., VCH, Weinheim 1997; Weisser ehl, K., Arpe, H. -J. , Chap. 3.4"Olefin-Metathese" in "Industrielle Organische Chemie", 4th edition, VCH, Weinheim 1994). Some types of catalysts have been described for metathesis with heterogeneous catalysts. In the temperature range of up to about 120 ° C, the use of Re2? 7 or Re (CO)? Or supported catalysts is usual (Mol, J. C, Chapter 4.12.2"Alkene Metathesis" in " Handbook of Heterogeneous Catalysis ", Eds. Ertl, G., Kndzinger, H., Weitkamp, J., VCH, Weinheim 1997). The supports available to a person skilled in the art, for this purpose, include AI2O3. This is present as eta or gamma AI2O3 in the finished catalyst. Molded bodies such as extruded, spheres, crushed or granulated material are usually used as precursors for support materials. During the production of the molded bodies, the support materials are normally calcined at temperatures of around 400-600 ° C, obtaining the pure gamma-Al203 phase, and possibly also, depending on the reaction conditions, eta-Al203. However, the phase transition for delta or theta-Al203 is not ruled out under these conditions.

DE 19,947,352 discloses a catalyst containing at least three components: an aluminum oxide support containing at least 0.5% delta-Al2 ?3, 0.01-20% by weight rhenium oxide and from 0.01-5% in weight of Cs. To obtain it, a catalyst precursor is first produced by applying the active components to pure delta-Al203 and subsequently calcined at temperatures of 750 ° C-1000 ° C. A disadvantage of the aforementioned catalysts is, first, the presence of an alkali metal component which gives rise to a reduced half-life of the catalyst by the formation Progressive thick alkali metal perrenate crystals, unreactive and at high concentrations, in different metathesis reactions can also give rise to the deterioration of the activity. Secondly, the calcination of catalyst precursors containing Re at temperatures of about 800 ° C and higher give rise to significant losses of the active component as a result of the vaporization of rhenium peroxide, which has a considerable adverse effect on the economy of the process.

It was an object of the invention to provide catalysts with support for the metathesis of hydrocarbons having a non-aromatic double bond C-C or triple bond C-C that maintain a high activity for a very long time of use. Another objective was to provide an economic process by means of which these catalysts can be produced.

Accordingly, we have found a process for producing a supported catalyst containing at least 75% by weight of AI2O3, whose proportion of AI2O3 in the delta or theta modification is, based on the proportion of? I2O3, at least 1 %, and that contains a compound of rhenium and, if appropriate, a promoter as an active component (A), which consists of: a) convert a customary support (S) containing at least 75% by weight of Al203 and to which, if appropriate, a promoter has been applied, it becomes a modified support (S) whose proportion of A1203 in the modification delta or theta is, based on the proportion of AI2O3, at least 1% calcining the usual support (S) at a temperature from 750 to 1100 ° C, b) producing a supported catalyst precursor from the modified support (S) by applying the active component (A) containing the rhenium compound to the modified support (S) and c) calcining the catalyst precursor with support at a temperature from 500 to 750 ° C.

As support (S), it is normal to use commercial AI2O3. This AI2O3 contains mainly gamma-Al203. The total ratio of delta and teta-2? 3 is, based on all modifications of AI2O3, in general at least < 1%. However, it is also possible to use I2O3 that has greater contents of delta and teta-Al2? 3 as support (S) if the catalyst with support has to have a higher content of it. It is important that the content of delta and teta-I2O3 in the support (S) used is lower than that contained in the supported catalyst of the invention.

Instead of using commercially available AI2O3 range supports, it is also possible to calcify a precursor thereof, for example hydrargillite, boehmite or pseudoboehmite, directly at temperatures necessary to form delta or teta-2 ?3 without first isolating as gamma-AI2O3 intermediate. . The molded support bodies with delta or teta content produced in this way are, in principle, possible to obtain as commercial niche products.

In addition to aluminum oxide, the support (S), if appropriate, may also contain other customary support materials, preferably materials selected from the group consisting of SiO2 aluminosilicates, Ti02, Zr02, MgO, Ce02 or ZnO.

To improve the physical properties of the catalyst, lubricants and additives such as graphite, cement, chalk or muscovite can also be incorporated in addition to the actual support material.

The catalyst of the invention and, if appropriate, the support (S) before the production of the catalyst, is preferably in the form of molded bodies. For the purposes of the present invention, molded bodies are bodies having geometries such as are generally customary for catalysts, i.e., spheres, crushed material, extruded or granulated. The smallest diameter of these molded bodies is usually more than 0.5 mm and the largest average diameter is usually less than 5 mm.

All customary molding methods such as extrusion or tapping are convenient for producing the molded bodies.

The calcination preferably takes place at a temperature from 750 to 1100 ° C. For the purpose of the present invention, calcination is heating in an atmosphere of oxidizing gas, that is, a gaseous atmosphere containing oxygen and otherwise inert constituents. The preferred gas atmosphere is air.

The increase of the time and increase of the calcination temperature allows to increase the proportion of AI2O3 in the delta or theta modification in relation to the gamut modification. Calcining temperatures above 1100 ° C are not recommended because in these conditions a transition to alpha-AI2O3 can be carried out and this is undesirable since the surface area of the support material then decreases too much. The total proportion of AI2O3 in the delta or theta modification is, based on the proportion of AI2O3, preferably at least 10%.

The support can, if appropriate, be treated with alcohols or can be modified to make it acid by the application of, for example, phosphoric acid, hydrochloric acid, sulfuric acid or ammonium acid phosphate. This modification can be carried out after or preferably before calcination.

For technical reasons, the calcination is usually carried out from 1 to 20 hours, but the time generally tends to be relatively unimportant. After the treatment, the supports have a surface area of from 20 to 200 m / g, preferably greater than 40 m / g, and a pore volume of at least 0.20 mL / g, preferably at least 0.35 mL / g. The structure of the pores of the modified support (S) after calcination is such that the maximum of the The distribution function for the pore diameter in the range of the mesopores (pore size from 2 nm to 50 nm) is usually in values above 10 mm, preferably above 12 nm. The determination of the pore size and the volume and its distribution is carried out in accordance with DIN 66133 of June 1993 and DIN 66134 of February 1968, published by the Deutsche Institut für Normung, e. V.

A precursor of a supported catalyst is produced from a modified support (S) by applying the active component (A) containing at least one rhenium compound. Possible rhenium compounds are sulphides, oxides, nitrides, carbonyls, halides or acids. Particular preference is given to ammonium perrenate or, in particular, perrhenic acid and rhenium heptoxide. The rhenium component can be applied to the support material by customary methods. These include, for example, methods such as impregnation in an excess solution, "dry impregnation" (ie, it is calculated based on the respective water absorptions, sublimation, especially by the carbonyls). If necessary, water is preferably used as a solvent for the rhenium components, but it is also possible to use organic solvents such as alcohols or dioxane The proportion of the active component (A) in the supported catalyst is usually from 0.1 to 30% by weight. Preference is given to rhenium oxide in an amount from 0.5 to 15% by weight as the active component. Rhenium oxide is present with particular preference in crystallites smaller than 1 nm at the surface. This corresponds to rhenium surface areas (determined by N20 chemisorption) greater than 0.4 m / g, as described in DE-A-19, 837, 203 for coated catalysts.

In addition to the rhenium component, the active component (A) may contain a promoter, that is, one or more other compounds that optimize the activity or selectivity of the finished catalyst. Examples that may be mentioned in this case are phosphorus oxide, iron oxide, zirconium oxide, silicon oxide, tantalum oxide, niobium oxide, tungsten oxide, molybdenum oxide, oxides of the elements of the series of the lanthanides, vanadium oxide, lead compounds or tin compounds. Additional compounds can be applied before, after or at the same time as the rhenium component, and intermediate calcinations at temperatures up to 600 ° C are also possible, if appropriate. On the other hand, according to the invention the presence of alkali metals is avoided, since they can form alkali metal perrenates, of thick, stable crystals, which shorten the total life of the catalyst, and secondly, in relatively high concentrations they can also directly reduce the activity of the catalyst , which would have to be compensated by a larger catalyst mass.

As a result of the proper choice of highly pure starting materials having a convenient specification, the supported catalysts of the invention generally have a total alkali metal content of less than 0.1% by weight (calculated as metal), preferably less than 700 ppm by weight. weight, particularly preferably less than 100 ppm by weight. In particular, the values for the higher homologs, ie the content of potassium, rubidium and cesium, are in each case less than 50 ppm by weight, preferably less than 30 ppm by weight, particularly preferably less than 10 ppm by weight .

Before use, the supported catalyst precursor is calcined at temperatures of at least 400 ° C, preferably at least 550 ° C, but no more of 750 ° C, in a stream containing oxygen, and subsequently cooled to the temperature of the reaction, preferably in an inert stream such as N2. The change of atmosphere containing oxygen to the inert gas atmosphere usually occurs at temperatures above 200 ° C, preferably at temperatures above 300 ° C, but not more than 750 ° C. If the catalyst is not going to be used immediately but will be temporarily stored, cooling may also occur in air, but in this case, according to the procedure described above, another activation must be carried out before use.

The most intense reflection of the aluminum oxides is usually in the range from 2 teta > 66th a 2 tit < 68 °. In addition, other reflections occur when delta and / or theta modifications are present. As a consequence, the maximum of at least one reflection of the supported catalysts of the invention must be in the range from 2 teta > 32.5 to 2 teta < 37.4 °, preferably at least the maximum of two reflections. Preference is given to supported catalysts in which at least one reflection whose maximum is in the range from 2 teta > 32.5 ° to 2 teat < 37.4 ° has an intensity ratio (accounts / accounts) to reflection in the interval from 2 teta > 66 ° to 2 teat < 68 ° of at least 0.05, preferably at least 0.15, with very particular preference at least 0.35.

Particular preference is also given to materials in which additional reflections in the range from 2 teta > 50.0 ° to 2 teat < 53.0 ° can be observed under the specified measurement conditions.

The supported catalysts of the invention are particularly useful for preparing a compound having a CC double bond or a non-aromatic CC triple bond (compound A) from another compound or mixture of other compounds having a CC double bond or a CC triple bond. non-aromatic (compound B) by placing the compound (B) in contact with a supported catalyst, which has been produced by the process of the invention, at a temperature from 50 to 500 ° C.

Processes such as these are generally known and described, for example, in "Industrielle Organische Chemie", Klaus Weissermel, Hans-Jürgen Erpel, 5th edition, Verlag Wiley, VCH, 1998, -Cap 3.4 and "Handbook of Heterogeneous Catalysis", edited by G. Ertl, H. Kndzinger and J. Weitkamp, Volume 5, VCH Verlagsgesellschaft mbH, Weinheim, Chapter 4.12.2, Alkene Metathesis, pages 2387 to 2399. However, these can also be used for the metathesis of esters, nitriles , ketones, aldehydes, acids or unsaturated ethers, as described for example in Xiaoding, X., Imhoff, P., von den Aardweg, CN, and Mol, J. C, J. Chem. Soc, Chem. Comm. (1985), p. 273. In the reaction of substituted olefins a co-catalyst, for example an alkyl tin, alkyl lead or aluminum alkyl is frequently used to obtain a further increase in activity.

In this case, supported catalysts produced by the processes according to the invention can be used in the same way as known metathesis catalysts.

The catalysts produced by the process of the invention are used with particular advantage in metathesis processes to prepare propene by metathesis of a mixture containing 2-butene and ethylene or 1-butene and 2-butenes, and to prepare 3-hexene and ethylene by 1-butene metathesis. The corresponding processes are described in detail in DE-A-19813720, EP-A-1134271, WO 02/083609, DE-A-10143160.

The aforementioned initial C4 compounds are normally supplied in the form of a raffinate II. The term "refined II" refers to the C4 fractions which generally have a butane content from 30 to 100% by weight, preferably from 40 to 98% by weight. In addition to butenes, saturated C4 alkanes, in particular, may also be present. The production of these refinings II is generally known and is described, for example, in EP-A-1134271.

In particular, it is possible to use olefinic mixtures containing 1-butene or 1-butene obtained by distilling a 1-butene-rich fraction of the raffinate II. 1-Butene can be obtained in the same way from the fraction rich in 2-butene that remains after subjecting the fraction rich in 2-butene to an isomerization reaction and subsequent fractional distillation to obtain a fraction rich in 1-butene and a fraction rich in 2-butene. This process is described in DE-A-10311139.

The catalysts produced by the process of the invention are particularly useful for reactions in liquid phase at temperatures from 10 to 150 ° C and a pressure from 5 to 100 bar.

Experimental part The following XRD measurements were carried out by means of a Siemens D-5000 diffractometer using Cu-K-alpha radiation, measurement with variable V-20 diaphragms on the primary and secondary side and a secondary monochromator to reduce the radiation of the fluorescence. The measurements were made in steps of 0.02 ° with a step time of 3.6 s. Signals that are close to each other can form an enlarged or asymmetric peak in the diffraction pattern due to overlap. Although in theory these can be separated by mathematical models, the results of a peaking procedure such as this can have a wide dispersion depending on the conditions of the contours of the model used. To rule out these uncertainties, the term reflection onwards will be used to understand a maximum that is clearly visible to the naked eye above noise. Therefore, the extended or asymmetric signals will be considered as unique reflections. The position of the maximum (= higher signal strength) is the crucial parameter in this case.

Example 1: Production of a catalyst according to the invention (A-85999) Commercial extrudates of D10-21 (extruded ga-A1203 from 1-5 mm from BASF AG) were heated at 850 ° C in air for 2 hours (during their production, the extrudates had been exposed to temperatures no higher than 600 ° C). C). The extrudates were subsequently impregnated with an aqueous solution of perrhenic acid at 90% of the water absorption and dried at 120 ° C in air for 6 hours. The temperature was subsequently increased to 520 ° C for a time of 2 hours, then to 550 ° C for another period of 15 minutes and the catalyst was calcined at this temperature for 2 hours. The catalyst was cooled and stored in air. The finished catalyst contained 9.5% by weight of Re2? 7. The pore volume determined by means of mercury porosimetry was 0.53 mL / g, and the surface area was 129 m / g. The maximum in the distribution function on the pore size distribution in the mesoporous interval was 13 nm. By means of X-ray diffraction (figure 1) was identified a mixture of the delta and theta-Al203 phases. You can see reflections that has maximums at 2 tit = 32.76 ° and 2 tit = 37.05 °. The ratio of intensities (counts / accounts) of the two reflections for the mean reflection at 67.07 ° is 0.36 and 0.45, respectively. Another very weak reflection could be observed at 2 tit = 50.6 °. The Cs content of this sample is < 10 ppm (limit of detection). The content of K and Na was in each case < 30 ppm (limit of detection).

Example 2: Production of a catalyst according to the invention (B = 86000) A catalyst was produced as described in Example 1, but the extrudates of the support were in this case pretreated at 1000 ° C in air for 2 hours.

The finished catalyst contained 9.9% by weight of R? 2? 7. The pore volume determined by means of mercury porosimetry was 0.44 mL / g, and the surface area was 89 m / g. The maximum in the distribution function on the pore size distribution in the mesoporous interval was 15 nm. By means of x-ray diffraction (Figure 2) a mixture of the delta and theta-Al2? 3 phases was identified. The reflections that had maximums at 2 tit = 32.79 ° and 2 tit = 36.73 ° can be observed. The ratio of intensities (accounts / accounts) of the two reflections to the mean reflection at 67.34 ° is 0.51 and 0.45, respectively.

A gamma phase could no longer be seen on the XRD. In addition you could see a reflection other than 2 tit = 50.7 °. The Cs content of this sample is < 10 ppm (limit of detection). The content of K and Na was in each case < 30 ppm (limit of detection).

Example 3: Production of a comparative example (C -85850) A catalyst was produced as described in Example 1, but the extrudates from the support were not pretreated.

The finished catalyst contained 9.0% by weight of Re2? 7. The pore volume determined by means of mercury porosimetry was 0.52 mL / g, and the surface area was 158 m / g. The maximum in the distribution function on the pore size distribution in the mesoporous interval was at 9.8 nm. By means of X-ray diffraction (Figure 3) is identified ? -Al03 pure. All the reflection maxima were outside the 2 teta interval from 32.5 ° to 37.4 °. Even in the interval from 2 teta > 50.0 ° and 2 teat < 53.0 °, no reflection could be seen in the conditions chosen for the measurement. The Cs content of this sample was < 10 ppm (limit of detection). The content of K and Na was in each case < 30 ppm (limit of detection).

Examples 4-6: Comparison of the performance of the A-C catalysts 9 g of catalyst were in each case installed in a reactor tube. The feed consists of 162 g / h of a mixture of approximately 85-90% of linear butenes, around 2.5% of isobutene and butanes as difference (refined II). To compensate for the somewhat lower rhenium content of Sample C, the feed rate was reduced by approximately 5% in this measurement. The reaction conditions are, in each case, 35 ° C and 35 bar. The composition of the stream leaving the reactor is monitored by means of an in-line GC. As representatives of numerous components, the quantities of the most important or largest products, namely propene, trans-2-pentene and trans-3-hexane, at different Measurement times are shown in the following table. All products that are not shown (ethylene, cis-2-pentene, cis-3-hexene, 2-methyl-2-butene and 2-methyl-2-pentene) have, in principle, a similar time profile and differences comparable in long run times.

It can be seen that the catalysts according to the invention have higher initial activities in all (differences up to about 40%) and specifically with respect to the lighter products (in this case propene) is deactivated somewhat more slowly, so that higher conversions are still achieved after a prolonged process time, which significantly increases the total yield.

Examples 7, 8: Transmission electromicrographs of catalysts containing alkali metals (Comparative Examples) Catalyst D (84325) was produced by impregnation of an aluminum oxide support containing about 250 ppm Na (based on the metal) as an impurity with perrhenic acid. Examination by means of TEM (transmission electron microscopy, Figure 4) showed crystals containing Na-Re, coarse. In contrast, pure rhenium oxide was formed in a highly dispersed phase in AI2O3 supports. These units were usually small at 4 nm and most of them could not be observed by means of TEM.

Another sample of Re2? 7 / Al2? 3, catalyst E (MS33) was subsequently impregnated with a solution of Cs (N03), dried and the catalyst was calcined again to 550 ° C. The catalyst contained 600 ppm Cs. In this case also the crystallites containing thick Cs-Re, in rod form they could be observed by means of TEM (Figure 5).

As one skilled in the art will know, catalytic reactions are carried out on the surface of these catalysts. Thus, the less the noble metals are required, the greater the dispersion of the active substance. The formation of alkali metal perrenona, thick crystals greatly reduces the dispersion of the Re 07 phase on the support materials containing AI2O3, so that generally a higher total charge with rhenium is needed to obtain the same catalytic activity.

Claims (11)

1. A process for producing a catalyst with support containing at least 75% by weight of I2O3, whose proportion of AI2O3 in the delta or theta modification is, based on the proportion of AI2O3, at least 1%, and which contains a rhenium compound and, if appropriate, a promoter as active component (A), the process consists of: a) converting a customary support (S) containing at least 75% by weight of AI2O3 and to which a promoter can, if appropriate, having been applied becomes a modified support (S) whose proportion of? I2O3 in the delta or theta modification is, based on the proportion of AI2O3, at least 1% calcining the usual support (S) at a temperature from 750 to 1100 ° C, b) producing a supported catalyst precursor from the modified support (S) by applying the active component (A) containing the rhenium compound to the modified support (S), and c) calcining the catalyst precursor with support at a temperature from 500 to 750 ° C.
2. 2. The process according to claim 1, characterized in that the total proportion of AI2O3 in the delta or theta modification is, based on the proportion of AI2O3, at least 10%.
3. 3. The process according to claim 1 or 2, characterized in that the proportion of AI2O3 in the theta modification is, based on the proportion of AI2O3, at least 10%.
4. 4. The process according to any of claims 1 to 3, characterized in that the support (S) contains AI2O3 together with components selected from the group consisting of Si02, aluminosilicates, TiO2, Zr? 2, MgO, Ce02 and ZnO.
5. 5. The process according to any of claims 1 to 3, characterized in that the amount of the rhenium compound used as active component (A) in step b) is selected from so that the catalyst contains from 0.01 to 1 mmol of rhenium per gram of catalyst.
6. 6. The process according to any of claims 1 to 5, characterized in that the supported catalyst has an XRD spectrum in which the maximum of the most intense reflection (main reflection) is in the range from 2 teta > 66 ° to 2 teat < 68 °, and the maximum of an additional reflection, or. the maximums of a plurality of additional reflections (secondary reflection) are in the range from 2 teta > 32.5 ° to 2 teat < 37.4 ° and the ratio of intensities of the respective secondary reflection to the main reflection is at least 0.05.
7. 7. The process according to any of claims 1 to 6, characterized in that the starting materials are selected so that the total amount of the alkali metal compounds, calculated as alkali metal, in the supported catalyst is less than 1000 ppm by weight .
8. 8. The process according to any of claims 1 to 7, characterized in that the initial compounds are selected so that the total amount of the cesium compounds, calculated as elemental cesium, in the supported catalyst is less than 50 ppm by weight.
9. 9. A process for preparing a compound having a CC double bond or non-aromatic CC triple bond (compound A) from another compound or mixture of other compounds having a double CC bond or non-aromatic CC triple bond (compound B) which it consists in putting the compound (B) in contact with a supported catalyst according to any of claims 1 to 8 at a temperature from 50 to 500 ° C.
10. 10. The process according to claim 9, characterized in that the compound (B) is 1-butene or a mixture of butenes containing 1-butene.
11. 11. A supported catalyst obtainable according to the processes described in claims 7 or 8.