Method for treating catalysts

Abstract

The object of the present invention is a method for treating a catalyst, which method comprises a hydrothermal treatment step in which the drying rate is slower than the subsequent drying step. The catalyst can be treated with the method according to the invention before use, preferably in the oligomerization, or after use, preferably in the oligomerization.

Description

[Technical Field]

[0001] The object of the present invention is a method for treating a catalyst, which method comprises a hydrothermal treatment step in which the drying rate is slower than the subsequent drying step. The catalyst can be treated with the method according to the invention before use, preferably in the oligomerization, or after use, preferably in the oligomerization. [Background technology]

[0002] There are few processes in industrial chemistry that do not use catalysts. Some of the catalysts used, for example in hydrogenation or oligomerization, contain nickel as the active metal. Hydrogenation involves the (partial) saturation of unsaturated carbon atoms by attaching hydrogen. Oligomerization involves the reaction of an unsaturated hydrocarbon with itself to form longer chain hydrocarbons known as oligomers (e.g., dimers, trimers, or tetramers). It is well known that catalysts used in chemical processes lose activity over time. This means that important parameters such as conversion or selectivity decrease over time. However, freshly prepared catalysts may not be active enough to be economically efficient. The basic solution to this problem is to pretreat new catalysts or to regenerate catalysts with reduced activity. Many corresponding processes have been published in the literature. In industrial scale processes, there is always a challenge to improve the process, including improving the catalysts used and their activity so that the process can be run more economically on an industrial scale. Summary of the Invention [Problem to be solved by the invention]

[0003] The present invention is therefore based on the problem of providing a process for treating a catalyst, preferably a catalyst for oligomerization, which allows improving the properties of the catalyst, in particular, when used in oligomerization, it should be possible to achieve higher selectivities and conversions in oligomerization without adversely affecting the mechanical properties, such as the service life and strength, of the catalyst. [Means for solving the problem]

[0004] The problem addressed by the present invention is solved by a method for treating a catalyst according to claim 1. Preferred embodiments are set out in the dependent claims. The method according to the invention is therefore a method for treating a nickel-containing catalyst, which comprises at least a) heat treating the catalyst at a temperature of 500°C to 900°C to remove carbon-containing deposits; b) impregnating the catalyst with an aqueous or ammoniacal solution containing a nickel compound; c) hydrothermally treating the catalyst by heating the catalyst from room temperature to a temperature ranging from 75°C to 150°C, preferably from 80°C to 110°C, and optionally maintaining the catalyst at said temperature until the residual moisture content is at most 30%, preferably at most 50%; d) drying the catalyst, wherein the drying rate is faster than the drying rate during the hydrothermal treatment in c), and the drying is carried out until the residual moisture content is at most 15%, preferably at most 10%; and e) calcining the catalyst; The present invention relates to a method comprising:

[0005] The oligomerization catalyst has a composition of 15-50% by weight NiO, preferably 15-40% by weight, 10-30% by weight Al2O3, 55-70% by weight SiO2, and 0.01-2.5% by weight, preferably 0.01-2% by weight alkali metal oxide, preferably sodium oxide. The figures are based on 100% by weight total composition. In a particularly preferred embodiment of the present invention, the oligomerization catalyst is substantially free of titanium dioxide and / or zirconium dioxide, and in particular contains less than 0.5% by weight, preferably less than 0.1% by weight, and particularly preferably less than 0.01% by weight titanium dioxide and / or zirconium dioxide in its total composition. According to the present invention, the BET specific surface area (calculated according to BET) of the oligomerization catalyst is further 150 to 400 m 2 / g, preferably 190 to 350 m 2 / g, particularly preferably 220 to 330m 2 / g. The BET surface area is determined by nitrogen physisorption according to DIN ISO 9277 (2014-01 edition).

[0006] In a further preferred embodiment, the oligomerization catalyst comprises mesopores and macropores, i.e., the pore size distribution is bimodal. The average pore diameter of the mesopores of the oligomerization catalyst according to the invention is 5 to 15 nm, preferably 7 to 14 nm, particularly preferably 9 to 13 nm. In contrast, the average pore diameter of the macropores of the oligomerization catalyst according to the invention is preferably 1 to 100 μm, particularly preferably 2 to 50 μm. The average pore volume of the oligomerization catalyst according to the invention, i.e., the average pore volume of the mesopores and macropores, is 0.5 to 1.5 cm. 3 / g, preferably 0.7 to 1.3 cm 3 / g. The average pore diameter and the average pore volume can be determined by mercury porosimetry in accordance with DIN 66133 (1993-06 edition).

[0007] The oligomerization catalyst according to the present invention is preferably in the form of granules. Furthermore, the average particle size (d50) of the oligomerization catalyst according to the present invention may be 0.1 mm to 7 mm, preferably 0.5 to 6 mm, particularly preferably 1 mm to 5 mm. The average particle size can be determined by imaging methods, in particular by the methods cited in the Genannten Verfahren standards ISO 13322-1 (ed. 2004-12-01) and ISO 13322-2 (ed. 2006-11-01). A suitable device for analyzing particle size is, for example, the Camsizer 2006 (Retsch Technology).

[0008] In a further preferred embodiment, the bulk crushing strength (BCS) of the oligomerization catalyst is greater than 0.5 MPa, preferably greater than 0.6 MPa, and particularly preferably greater than 0.8 MPa. The BCS value is a measure of the mechanical strength of mineral granules. The bulk crushing strength (BCS) of a solid is understood to mean the parameter defined as the pressure in MPa at which a fine fraction of 0.5% by mass (i.e., particles sieved using a screen with a mesh size of 0.425 mm) is formed when a solid sample is subjected to pressure via a piston in a tube. For this purpose, 20 ml of solid is pre-sieved through a screen (mesh size: 0.425 mm) and packed into a cylindrical sample tube (internal diameter: 27.6 mm, wall thickness: 5 mm, height: 50 mm), and a 5 ml steel ball (diameter: 3.9 mm) is placed on top of the solid. The solid is then subjected to different pressures (increasing pressure) for 3 minutes. The fine fraction formed by pressing is then removed by screening and in each case weighed in total to determine the percentage of the fraction, this process being carried out until the amount of the fine fraction reaches 0.5% by weight.

[0009] The oligomerization catalyst may also be characterized by its maximum injection density. In a preferred embodiment, the maximum injection density of the oligomerization catalyst according to the present invention is between 0.1 and 2 g / cm. 3 , preferably 0.2 to 1.5 g / cm 3 , and particularly preferably 0.3 to 1.0 g / cm 3The pour density can be measured via a measuring cylinder. The measuring cylinder is filled with a predetermined volume of the solid to be investigated via a suitable weighing device, such as a DR100 device (Retsch), and the measuring cylinder is weighed. The maximum pour density can be determined from the mass and volume. It may be necessary to subtract the residual moisture from the sample mass.

[0010] The oligomerization catalyst according to the present invention is prepared by a process which includes the following general steps. 1) granulating a mixture of an amorphous silica-alumina support material, an Al-containing and a Si-free binder, and at least a portion of a nickel source, and optionally an alkali source; 2) treating (impregnating) the particulate material produced in step a) with at least a portion of the nickel source and / or alkalinity source, provided that the nickel source and / or alkalinity source are entirely unmixed with the silica-alumina support material and the Al-containing and Si-free binder; and 3) calcining the granules to produce the oligomerization catalyst. is. Corresponding methods and the exact conditions are known and are disclosed, for example, in European Patent Application No. 3549669, European Patent Application No. 3546065 or European Patent Application No. 3542898.

[0011] After the preparation of the catalyst, said catalyst may be used for the oligomerization of olefins. However, the catalyst may be subjected to the process according to the invention after its preparation and before use, and a further hydrothermal step may be carried out during which certain steps of the preparation process are repeated. The direct preparation of the catalyst using a hydrothermal treatment step does not form part of the present invention. [Effects of the Invention]

[0012] The method according to the present invention can also be used to regenerate a catalyst that has already been used in oligomerization. As the use time of an oligomerization catalyst in oligomerization increases, the conversion efficiency and / or selectivity may decrease, for example, due to the deposition of organic compounds. The catalyst according to the present invention can be used to regenerate after use in an oligomerization reaction, i.e., its oligomerization activity may be improved compared to its previous state. DETAILED DESCRIPTION OF THE INVENTION

[0013] Each step will be described in more detail below. Process a) After the oligomerization catalyst is used in the oligomerization reaction, organic substances may precipitate. Removal of such precipitates may be desirable. Removal of at least a portion of the organic compounds deposited in the catalyst is preferably achieved in step a) by thermal treatment (oxidation) to form carbon oxides and water. Step a) may be carried out continuously or discontinuously in a furnace, for example, a rotary kiln or a shaft furnace. For this purpose, the oligomerization catalyst is fed into the furnace and maintained at a predetermined furnace temperature, preferably between 500°C and 900°C, particularly preferably between 600°C and 850°C. Step a) usually uses combustion air. The combustion air used is preferably fed countercurrently, and furthermore, additional air may be optionally blown into the granules (oligomerization catalyst) through a suitable inlet to ensure faster oxidation.

[0014] Step b) Step b) involves impregnating the catalyst obtained from step a) with an aqueous or ammoniacal solution. In the context of the present invention, impregnation should be understood to mean contacting the catalyst with an aqueous or ammoniacal solution, which can be carried out, for example, by spraying until a liquid film permanently forms on the surface (incipient wetness). The impregnation introduces at least the desired moisture content for the subsequent hydrothermal treatment. According to the invention, it is preferred if the aqueous or ammoniacal solution contains a nickel compound, which allows for the deposition of additional amounts of nickel on the oligomerization catalyst. In principle, any soluble nickel compound can be used to prepare the aqueous or ammoniacal nickel solution, such as nickel nitrate (Ni(NO3)2), nickel acetate (Ni(ac)2), nickel acetylacetonate (Ni(acac)2), nickel sulfate (NiSO4), nickel citrate or nickel carbonate (NiCO3). It has proven particularly advantageous to use NiHAC solutions, i.e. ammoniacal Ni(CO3) solutions, which can be used with nickel contents of 0.5 to 14% by weight, in particular 2 to 10% by weight, very particularly 4 to 8% by weight.

[0015] Process c) After the impregnation, a hydrothermal treatment is carried out in step c). The hydrothermal treatment is carried out by heating the catalyst from room temperature to a temperature in the range of 75°C to 150°C, preferably 80°C to 110°C, and, depending on the case, maintaining said temperature until the residual moisture content is at most 30% or 50%. The term "residual moisture content" refers to the state of the catalyst before the hydrothermal treatment, when the residual moisture content of the catalyst is 100%. Therefore, the catalyst is not dried at all by the hydrothermal treatment, or is dried only slowly, if at all.

[0016] The hydrothermal treatment is the core of the method and must be clearly distinguished from the subsequent drying in step d). The drying rate (the mass loss of evaporable components such as water or ammonia per unit time (e.g., minute)) in the hydrothermal treatment is significantly lower than that in the drying in step d). The hydrothermal treatment in step c) can be carried out at atmospheric pressure or at a pressure higher than atmospheric pressure but not under vacuum. The hydrothermal treatment is preferably carried out in an apparatus suitable for limiting the drying rate. The hydrothermal treatment in step c) can be carried out, for example, in a sealed container, so that the drying rate based on the volume of the container is zero. If the hydrothermal treatment is carried out in a sealed container, pressure will build up due to the evaporating water and ammonia. In this case, for safety reasons, the sealed container must have a pressure relief valve to prevent excessive pressure.

[0017] Step d) The impregnated oligomerization catalyst is then dried in a suitable drying apparatus, for example a belt dryer or a cone dryer equipped with an air flow, at a temperature of 80°C to 250°C, preferably 100°C to 220°C, and under atmospheric pressure or vacuum. The drying rate in step d) is higher than that in the hydrothermal treatment in step c). In a preferred embodiment, the drying apparatus and the apparatus for the hydrothermal treatment are not the same. Instead, the oligomerization catalyst that has not been completely dried can be removed from the apparatus in which step c is performed and introduced into the drying apparatus.

[0018] Process e) Step e) is the final calcination. The calcination of the oligomerization catalyst may be carried out continuously or discontinuously in a suitable furnace, such as a shaft furnace or a rotary kiln. In the case of continuous calcination, it is more preferred if the gas passes through the oligomerization catalyst (granules) in countercurrent. The gas used may be air, nitrogen or a mixture thereof. The gas flow should be between 0.2 and 4 m per kg of granules per hour. 3 and the inlet temperature of the gas may be between 400° C. and 900° C., preferably between 450° C. and 750° C. In addition to this heat introduced via the gas, energy may be introduced by active heating of the furnace walls. The calcination temperature in the calciner may be 400°C to 900°C, preferably 450°C to 850°C. This temperature can be maintained for several hours, preferably 0.5 to 20 hours, and particularly preferably 1 to 10 hours, before the granules are cooled. Cooling is preferably carried out in an air stream. The oligomerization catalyst according to the invention / the catalyst produced or regenerated by the process according to the invention can be used in particular for the oligomerization of C3-C6 olefins, preferably C3-C5 olefins, particularly preferably C4 olefins, or olefin-containing starting mixtures based thereon. The olefins or olefin-containing starting mixtures are used as reactant streams.

[0019] After carrying out the process according to the invention, the catalyst can be used for the oligomerization of olefins. The subject of the invention is therefore also a process for the oligomerization of C3-C6 olefins, in which an olefin-containing starting mixture containing C3-C6 olefins is passed over a catalyst in at least one reaction zone, the catalyst being treated by the process according to the invention. The olefins used in the process according to the invention include C3-C6 olefins, preferably C3-C5 olefins, particularly preferably C4 olefins, or olefin-containing starting mixtures based thereon, which may contain similar proportions of alkanes. Suitable olefins are, inter alia, α-olefins, n-olefins, and cycloalkenes. The olefins used as reactants are preferably n-olefins. In a particularly preferred embodiment, the olefin is n-butene. The term "olefin-containing starting mixtures based thereon" in the present invention should be understood to include any mixture containing the relevant C3-C6 olefins to be oligomerized in an amount sufficient to carry out the oligomerization. The olefin-containing starting mixture preferably does not actually contain further unsaturated and polyunsaturated compounds, such as dienes or acetylene derivatives. It is preferred to use an olefin-containing starting mixture containing less than 5% by weight, in particular less than 2% by weight, of branched olefins relative to the olefin. Also preferred is an olefin-containing input mixture containing less than 2% by weight of branched olefins, in particular isoolefins.

[0020] Propylene (C3) is a readily available commodity chemical produced on an industrial scale by cracking naphtha. C5 olefins are present in light petroleum fractions from refineries or crackers. Industrial mixtures containing linear C4 olefins include light petroleum fractions from refineries, C4 fractions from FC crackers or steam crackers, mixtures from Fischer-Tropsch synthesis, mixtures from butane dehydrogenation, and mixtures formed by metathesis or other industrial processes. A mixture of linear butenes suitable for the process of the present invention can be obtained, for example, from the C4 fraction of a steam cracker. Butadiene is removed in the first step. This is achieved either by extraction or extractive distillation of butadiene or by its selective hydrogenation. Both methods result in a substantially butadiene-free C4 fraction, i.e., raffinate I. In the second step, isobutene is removed from the C4 stream, for example, by reaction with methanol to produce methyl tert-butyl ether (MTBE). Other possibilities include the reaction of isobutene from raffinate I with water to produce tert-butanol, or the acid-catalyzed oligomerization of isobutene to produce diisobutene. The isobutene-free C4 fraction, raffinate II, contains linear butenes and, if necessary, butane. 1-butene can optionally be further removed by distillation. Both the fraction containing 1-butene and the fraction containing 2-butene can be used in the process according to the invention. In a further preferred embodiment, the C4-olefin-containing material stream is fed to the process as an olefin-containing input mixture. Suitable olefin-containing starting mixtures are in particular raffinate I (a butadiene-free C4 fraction from a steam cracker) and raffinate II (a butadiene-free C4 fraction from a steam cracker and an isobutene-free C4 fraction). Another possibility for producing a suitable olefin-containing starting mixture is to hydroisomerize raffinate I, raffinate II, or a similarly constituted hydrocarbon mixture in a reaction column, which gives a mixture of, inter alia, 2-butene, small amounts of 1-butene, and possibly n-butane, as well as isobutane and isobutene.

[0021] The oligomerization is generally carried out at temperatures ranging from 50°C to 200°C, preferably from 60°C to 180°C, preferably from 60°C to 130°C, and at pressures ranging from 10 to 70 bar, preferably from 20 to 55 bar. For this reason, when the oligomerization is carried out in the liquid phase, the pressure and temperature parameters must be selected such that the starting material stream (olefin or olefin-containing starting mixture used) is in the liquid phase. The mass loading of the olefin-containing starting mixture (mass of starting material per unit catalyst mass per unit time; mass loading (WHSV)) is calculated as the mass loading per hour (=1h -1 ) per 1g of catalyst per 1g of starting material ~ 190h -1 , favorably 2h -1 ~35h -1 , especially advantageous 3h -1 ~25h -1 However, typical conditions are known to those skilled in the art.

[0022] The oligomers produced by the process according to the invention are used, inter alia, for the production of aldehydes, alcohols, and carboxylic acids. For example, the dimerization of linear butenes leads to nonanal mixtures (nonanal mixtures) upon hydroformylation. This can be oxidized to the corresponding carboxylic acids or hydrogenated to produce C9 alcohol mixtures. C9 acid mixtures can be used to produce lubricants or desiccants. C9 alcohol mixtures are precursors for the production of plasticizers, particularly diisononyl phthalate, diisononyl terephthalate, diisononyl cyclohexane-1,4-dicarboxylate, or diisononyl cyclohexane-1,2-dicarboxylate. The invention will now be described in more detail with reference to examples, in which alternative embodiments of the invention are also provided. [Example]

[0023] Original catalyst material The catalyst material was obtained from a manufacturing plant for butene oligomerization and contained AlO 3 / The typical composition is about 20% by weight NiO on SiO2. The spent catalyst material is regenerated by first undergoing a heat treatment in a rotary kiln at a temperature of 550-650°C in a first step, followed by post-impregnation with a 5% Ni solution in a second step, followed by drying in a drying cabinet at about 110-120°C for more than 10 hours to a residual moisture content of about 15%, followed by calcination in a tube furnace at 650°C. Comparative catalyst 2 was not subjected to a further hydrothermal treatment. To produce catalyst 1 according to the invention, hydrothermal treatment was performed before drying in a drying cabinet. The material was subjected to a hydrothermal treatment in a drying cabinet for 6 hours at 110°C to a residual moisture content of about 30% in a partially open container (closed with a vented screw cap with a PTFE membrane), resulting in a faster drying rate during subsequent drying. The two catalysts thus prepared were used for catalytic testing as follows: In each case, approximately 350 g of catalyst was introduced into a metal tube with an internal diameter of 21 mm. Before and after the catalyst addition, glass beads with a diameter of 2 mm were added, which served as preheating and cooling phases. The oligomerization was carried out with a feed pressure of 30 bar and a butene loading of 2 g / h per gram of catalyst, and the reaction temperature was varied between 80 and 100 °C. The products were analyzed by gas chromatography for butene conversion and octene linearity. The composition of the feed for the oligomerization is shown in Table 1 below. Table 1: Feedstream composition

[0024] [Table 1] The conversions achieved on the feed stream as a function of temperature for catalyst 1 (invention) and catalyst 2 (non-invention), as well as the ISO index derived therefrom, are reported in Table 2. The linearity of the oligomerization products or dimers formed is described by the ISO index, which represents the average number of methyl branches in the dimer. For example, (for butene as reactant) for the C8 fraction, n-octene is added as 0, methylheptene as 1, and dimethylhexene as 2. The lower the ISO index, the more linear the structure of the molecules in each fraction. The ISO index is calculated according to the following general formula:

[0025]

number

[0026] Table 2: Catalytic results

[0027] [Table 2] It is clear that catalyst 1 of the present invention achieves significantly higher conversions, in some cases at comparable or lower ISO indices. This is surprising, since high conversions can reduce the linearity of oligomers in the product mixture. Therefore, further hydrothermal treatment reliably increases the effectiveness of the catalyst, regardless of temperature.

Claims

1. A method for treating a nickel-containing catalyst, comprising at least the following: a) A step of heat-treating the catalyst at a temperature of 500°C to 900°C to remove carbon-containing deposits, b) The step of impregnating the catalyst with an aqueous solution or ammonia solution containing a nickel compound, c) A step of hydrothermally treating the catalyst, wherein the hydrothermal treatment is carried out by heating the catalyst from room temperature to a temperature in the range of 75°C to 150°C, and, if necessary, maintaining the temperature until the residual moisture content is 30% or less. d) A step of drying the catalyst, wherein the drying rate in step d) is higher than the drying rate in the hydrothermal treatment in step c), and the drying step is carried out until the remaining moisture content is 15% or less. e) A step of calcining the catalyst, Methods that include...

2. The method according to claim 1, wherein the processing method is carried out following the production of the catalyst or following its regeneration after use in a heterogeneous catalytic reaction.

3. The nickel compound is nickel nitrate (Ni(NO) ３ ) ２ ), nickel acetate (Ni(ac) ２ ), nickel acetylacetonate (Ni(acac) ２ ), nickel sulfate (NiSO ４ ), nickel citrate or nickel carbonate (NiCO2) ３ The method according to claim 1, selected from the group consisting of ).

4. The aqueous solution or ammonia solution used is ammonia Ni(CO) ３ The method according to claim 1, wherein the solution is...

5. The method according to claim 1, wherein the heat treatment in a) above is performed at a temperature of 600°C to 850°C.

6. The method according to claim 1, wherein the duration of the hydrothermal treatment in c) is 1 to 24 hours.

7. The method according to claim 1, wherein the drying step in d) is performed at a temperature in the range of 80°C to 250°C.

8. The method according to claim 1, wherein the drying step in d) is performed such that the loss on drying (LOD) of the obtained dried material at 110°C is 5% by mass or less.

9. The method according to claim 1, wherein the drying rate in d) is twice the drying rate in c).

10. The method according to claim 1, wherein the firing step in e) above is performed at a temperature of 400°C to 900°C.

11. The method according to claim 1, wherein the firing step in e) above is carried out in an airflow, a nitrogen flow, or a combination thereof.

12. The catalyst has a composition of 15% to 50% by mass of NiO, 10% to 30% by mass of Al ２ O ３ , 55% to 70% by mass of SiO ２ , and 0.01% to 2.5% by mass of an alkali metal oxide, the method according to claim 1.

13. The catalyst, when measured by nitrogen physicoadsorption, yields 150 to 400 m ２ The method according to claim 1, having a BET specific surface area of ​​1 / g.

14. A method for oligomerizing C3-C6 olefins, wherein an olefin-containing feed mixture comprising the C3-C6 olefins passes over a catalyst in at least one reaction zone, and the catalyst is treated by the method of claim 1.