WO2006018133A1 - Catalyst containing iron oxide(s) alkali metal compound(s) and cerium oxide(s) - Google Patents

Catalyst containing iron oxide(s) alkali metal compound(s) and cerium oxide(s) Download PDF

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Publication number
WO2006018133A1
WO2006018133A1 PCT/EP2005/008406 EP2005008406W WO2006018133A1 WO 2006018133 A1 WO2006018133 A1 WO 2006018133A1 EP 2005008406 W EP2005008406 W EP 2005008406W WO 2006018133 A1 WO2006018133 A1 WO 2006018133A1
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Prior art keywords
cerium
catalyst
oxide
dehydrogenation
bet surface
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PCT/EP2005/008406
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German (de)
French (fr)
Inventor
Christian Walsdorff
Otto Hofstadt
Gerald Vorberg
Reinhard KÖRNER
Harald Freiberger
Christophe Houssin
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Basf Aktiengesellschaft
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Publication of WO2006018133A1 publication Critical patent/WO2006018133A1/en

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
    • B01J23/70—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper
    • B01J23/76—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper combined with metals, oxides or hydroxides provided for in groups B01J23/02 - B01J23/36
    • B01J23/84—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper combined with metals, oxides or hydroxides provided for in groups B01J23/02 - B01J23/36 with arsenic, antimony, bismuth, vanadium, niobium, tantalum, polonium, chromium, molybdenum, tungsten, manganese, technetium or rhenium
    • B01J23/85—Chromium, molybdenum or tungsten
    • B01J23/88—Molybdenum
    • B01J23/887—Molybdenum containing in addition other metals, oxides or hydroxides provided for in groups B01J23/02 - B01J23/36
    • B01J23/8872—Alkali or alkaline earth metals
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
    • B01J23/70—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper
    • B01J23/76—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper combined with metals, oxides or hydroxides provided for in groups B01J23/02 - B01J23/36
    • B01J23/83—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper combined with metals, oxides or hydroxides provided for in groups B01J23/02 - B01J23/36 with rare earths or actinides
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C5/00—Preparation of hydrocarbons from hydrocarbons containing the same number of carbon atoms
    • C07C5/32—Preparation of hydrocarbons from hydrocarbons containing the same number of carbon atoms by dehydrogenation with formation of free hydrogen
    • C07C5/327—Formation of non-aromatic carbon-to-carbon double bonds only
    • C07C5/333—Catalytic processes
    • C07C5/3332—Catalytic processes with metal oxides or metal sulfides
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
    • B01J37/0009—Use of binding agents; Moulding; Pressing; Powdering; Granulating; Addition of materials ameliorating the mechanical properties of the product catalyst
    • B01J37/0018—Addition of a binding agent or of material, later completely removed among others as result of heat treatment, leaching or washing,(e.g. forming of pores; protective layer, desintegrating by heat)
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
    • B01J37/0009—Use of binding agents; Moulding; Pressing; Powdering; Granulating; Addition of materials ameliorating the mechanical properties of the product catalyst
    • B01J37/0027—Powdering
    • B01J37/0045—Drying a slurry, e.g. spray drying
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C2523/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group C07C2521/00
    • C07C2523/70—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group C07C2521/00 of the iron group metals or copper
    • C07C2523/76—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group C07C2521/00 of the iron group metals or copper combined with metals, oxides or hydroxides provided for in groups C07C2523/02 - C07C2523/36
    • C07C2523/84—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group C07C2521/00 of the iron group metals or copper combined with metals, oxides or hydroxides provided for in groups C07C2523/02 - C07C2523/36 with arsenic, antimony, bismuth, vanadium, niobium, tantalum, polonium, chromium, molybdenum, tungsten, manganese, technetium or rhenium
    • C07C2523/85—Chromium, molybdenum or tungsten
    • C07C2523/88—Molybdenum
    • C07C2523/887—Molybdenum containing in addition other metals, oxides or hydroxides provided for in groups C07C2523/02 - C07C2523/36

Definitions

  • the invention relates to a catalyst containing iron oxide (s), alkali metal compound (s) and cerium oxide (s), wherein in the preparation of the catalyst as Cer component (s) Cercarbonat hydrate (s) having a BET surface area of less than 0.30 m 2 / g are used.
  • the invention further relates to a catalyst bed which consists of at least 25% by weight of catalysts which contain iron oxide (s), alkali metal compound (s) and cerium oxide (s), in the preparation of the catalysts as cerium component (n) Cercarbonate hydrate (s) having a BET surface area of less than 0.30 m 2 / g are used.
  • the invention relates to a process for the dehydrogenation of alkylaromatic compounds.
  • EP-A 177 832 describes dehydrogenation catalysts comprising iron oxide, potassium oxide, molybdenum oxide, magnesium oxide, calcium oxide and cerium oxide, which is prepared using commercially available ceria as starting material.
  • EP-A 894 528 discloses dehydrogenation catalysts which also contain iron oxide, potassium oxide, molybdenum oxide, magnesium oxide, calcium oxide and cerium oxide using aqueous cerium nitrate solution as the feedstock.
  • cerium nitrate as starting material has the disadvantage that nitrogen oxides are liberated during the calcination of the catalyst.
  • DE-A 101 54 718 describes catalysts comprising iron oxide, potassium oxide, molybdenum oxide, magnesium oxide, calcium oxide and cerium oxide, which is prepared using cerium carbonate hydrate.
  • Cerium oxides are generally used in an amount of 5 to 60% by weight as carbonates, oxides, nitrates or hydroxides. it is described that by cerium Polari ⁇ tion of the Fe-O bond and obstruction of reaction of Fe 3+ to Fe 3 O 4 ty the Aktivi ⁇ and increased stability of the K-Fe phases.
  • the object of the invention was therefore to show a catalyst for the dehydrogenation of alkylaromatic compounds, which has improved alkylaromatic conversion with improved or constant alkenyl aromatic selectivity. Furthermore, the object was to reduce the benzene selectivity for the same or improved activity.
  • Lower benzene selectivity generally leads to a reduced amount of dehydrogenation gas because of the parallel reduced formation of, in particular, ethylene and carbon dioxide. This is particularly important in styrene plants with limited vacuum compressor performance of importance.
  • the object has been achieved with the aid of a catalyst comprising iron oxide (s), alkali compound (s) and cerium oxide (e), in which case the preparation of the catalyst as cerium component (s) comprises cercarbonate hydrate (e) having a BET surface area be used of less than 0.30 m 2 / g.
  • the BET surface area of the starting material cercarbonate hydrate is preferably less than 0.25 m 2 / g, in particular, the BET surface area of the cercarbonate hydrates is from 0.01 to 0.20 m 2 / g. A suitable method for measuring the BET surface area is described below.
  • the sulfur content of the cercarbonate hydrate used according to the invention is advantageously less than 100 ppm by weight, in particular less than 20 ppm by weight.
  • FIG. 3 shows, by way of example, scanning electron microscopy (SEM) images of rhodia cercarbonate hydrates used according to the invention.
  • Fig. 1 Wildhelm Priem GmbH & Co. KG
  • Fig. 2 Talbacher Auermet
  • the surfaces of the cercarbonate hydrates used according to the invention have, in comparison with the cercarbonate hydrates used in the prior art, larger crystals and in particular a significantly reduced proportion of smaller crystals grown on.
  • Cercarbonate hydrate is a pasty solid with varying water content.
  • the cercarbonate hydrate to be used according to the invention has a composition of approximately (Ce) 2 (CO 3 ) 3 .8H 2 O and an XRD structure analogous to lanthanite (Gmelin Handbook Rare Earth A7 p.191).
  • the use of more highly dehydrated cerium carbonates, in particular commercially available so-called dry cerium carbonates, is less preferred and generally leads to catalysts with reduced performance properties.
  • Cercarbonate hydrate can be obtained from numerous suppliers, for example from Schwarzacher Auermet principless GmbH in Austria, Wilhelm Priem GmbH & Co. KG in Germany or Rhodia in France.
  • the BET surface area of the cercarbonate hydrates varies widely and is 0.38 m 2 / g (Wilhelm Priem GmbH & Co. KG), 0.35 m 2 / g (Treibacher Auermet) and 0.18 m 2 / g. g (Rhodia).
  • catalysts are used whose preparation as cerium component at least 25 wt .-% ceric carbonate hydrate with a BET surface area of less than 0.30 m 2 / g are used.
  • the remaining up to 75 wt .-% may be Cercar ⁇ carbonate hydrates with a higher BET surface area or other cerium compounds such as cerium nitrates, oxides or hydroxides.
  • the invention further relates to catalyst beds which consist of at least 25% by weight of catalyst according to the invention.
  • the catalyst beds consist of at least 30% by weight, preferably at least 50% by weight, of catalysts according to the invention.
  • the catalysts of the invention may be evenly distributed over the catalyst bed or concentrated at one or more locations.
  • the catalysts according to the invention are used uniformly distributed over the entire dehydrogenation catalyst bed, in particular without the use of a further dehydrogenation catalyst from the prior art.
  • the catalyst according to the invention is particularly suitable for the dehydrogenation of hydrocarbons which have at least one saturated functional group, for example alkenes to the corresponding 1,3-alkadienes, preferably alkylaromatic compounds to the corresponding alkenylaromatic compounds.
  • Suitable alkylaromatic compounds are all aromatic and heteroaromatic alkyl compounds, preference is given to those in which the alkyl radical is unbranched or branched and contains two to six C atoms.
  • Suitable aromatic radicals are mono-, di- or trinuclear, preferably mono- or binuclear, particularly preferably einker ⁇ nige aromatics.
  • isopropylbenzene (cumene), ethylbenzene, 1, 1-diphenyl benzene and 1,2-diphenylethane (bibenzyl), preferably isopropylbenzene (cumene), ethylbenzene and 1,1-diphenylbenzene, more preferably ethylbenzene.
  • Suitable heteroaromatic radicals are mono-, di- or trinuclear, preferably mononuclear or dinuclear, particularly preferably mononuclear, five-membered heteroaromatic compounds having one to three nitrogen atoms and / or one oxygen atom or one sulfur atom, one, two or three ⁇ Ripe, preferably mono- or binuclear, particularly preferably mononuclear, six-membered heteroaromatic having one to three nitrogen atoms as heteroatoms, in particular pyridines, such as 2-ethylpyridine, 3-ethylpyridine, 4-ethylpyridine and 5-ethyl-2-methylpyridine, be ⁇ preferably 2-ethylpyridine and 5-ethyl-2-methylpyridine.
  • the catalysts according to the invention typically contain a number of promoters, depending on their field of use. Suitable promoters for a dehydrogenation catalyst are, in addition to cerium compounds, advantageously compounds of calcium, magnesium, molybdenum, tungsten, chromium and titanium.
  • the weight ratio of potassium (calculated as K 2 O) to iron oxide (calculated as Fe 2 O 3 ) is generally from 0.01: 1 to 2: 1, preferably from 0.1: 1 to 1: 1.
  • the catalysts preferably contain further promoters (calculated as oxides) in a weight ratio to the iron oxide of from 0.01: 1 to 1: 1, preferably from 0.02: 1 to 0.5: 1.
  • the catalyst according to the invention has in particular the following composition:
  • Iron corresponding to 40-90% by weight of Fe 2 O 3
  • potassium corresponding to 1-40% by weight as K 2 O
  • Cerium corresponding to 1 to 25% by weight of Ce 2 O 4 , in particular 5 to 15% by weight of Ce 2 O 4 ,
  • Magnesium corresponding to 0-10% by weight of MgO
  • Tungsten corresponding to 0-10% by weight of WO 3
  • molybdenum corresponding to 0-10% by weight of MoO 3
  • Vanadium corresponding to 0 - 10 wt .-% V 2 O 5 wherein said components add up to 100 wt .-%.
  • the starting materials used can be compounds of the promoters present in the finished catalyst, or compounds which convert during the preparation process into compounds present in the finished catalyst.
  • the starting materials can also Additives may be added to improve processability, mechanical strength or pore structure. Examples of such substances are potato starch, celluloses, stearic acid, graphite and / or Portland cement.
  • the starting materials can be mixed directly in a mixer, kneader or preferably a Mix-Muller.
  • the starting materials can also be slurried in a spray mixture and processed in a spray dryer to form a spray powder.
  • the starting materials are preferably processed in a Mix-Muller or kneader with the addition of water to form an extrudable mass.
  • the extrudable mass is then extruded, dried and calcined.
  • Preferred strand forms comprise extrudates of 2 to 10 mm in diameter, in particular 2.5 to 6 mm.
  • the cross-section of the extrudates may be round or in other forms.
  • extrudates with rotationally symmetrical cross section in particular with a diameter of 2 to 4 mm, preferably of 3 mm, as well as extrudates with a star-shaped or those with a gear-toothed ("toothed-wheel") cross section, in particular with a diameter of 3 to 7, preferably 3.5 mm, 4.5 mm or 6 mm.
  • the shaping of the catalysts can also be carried out by tableting.
  • the extruded or optionally tabletted shaped catalyst bodies are then usually dried and subjected to calcining. The drying is preferably carried out on a belt dryer at temperatures between 100 and 200 0 C.
  • the calcination is preferably in a rotary kiln at temperatures between 500 and 1000 0 C, preferably between 700 and 1000 ° C, in particular zwi ⁇ rule 800 and 950 0 C, and particularly preferably 850 to 900 0 C fürge leads.
  • carbonate-containing feedstocks convert to oxides.
  • Potassium and iron oxides typically form mixed potassium ferrite crystal structures in the most preferred temperature range.
  • the dehydrogenation of hydrocarbons can be carried out by all methods known to the person skilled in the art.
  • the dehydrogenation of alkylaromatics to alkenylaromatics is preferably carried out in adiabatic or isothermal processes, in particular in adiabatic processes.
  • the reaction is generally distributed to several reactors in series, preferably radial flow reactors. Preferably, two to four reactors are connected in series. In each reactor is a Fest ⁇ bed with dehydrogenation catalysts.
  • ethylbenzene In the dehydrogenation of ethylbenzene to styrene, as is generally practiced today in multi-stage processes in so-called adiabatic processes, ethylbenzene is typically heated to temperatures together with steam, advantageously in an amount of less than 30% by weight, based on ethylbenzene around 500 0 C by means of a heat exchanger heated and mixed directly before entering the first reactor with superheated steam from a steam superheater, so that the desired inlet temperature in the first reactor is usually between 600 and 650 ° C.
  • the mass ratio of water vapor (total steam) to ethylbenzene when entering the bed of the dehydrogenation catalyst in the first reactor is advantageously 0.7: 1 to 2.5: 1.
  • the process is preferably operated at reduced pressure, typical reactor pressures are in the range of 300 to 1000 mbar.
  • the preferably hollow-cylindrical catalyst beds (radial flow reactors) are flowed through from the inside to the outside.
  • the reaction mixture Before entering the next reactor, the reaction mixture is advantageously brought back to temperatures of usually 600 and 650 0 C via a heat exchanger by means of superheated steam.
  • the pressure at the outlet of the last reactor should not be more than 700 mbar, more preferably not more than 600 mbar and in particular not more than 500 mbar.
  • a bed of an oxidation catalyst with oxygen supply for combustion of a subset of the hydrogen formed in the previous reactor can be set up, as for example in the German An ⁇ message with the application file number 102004015800.2 is described.
  • the volume ratio of the Schüttun ⁇ conditions of oxidation catalyst and dehydrogenation catalyst per reactor is generally 0.1: 1 to 1: 1.
  • an integrated oxidation catalyst this is preferably arranged upstream of the dehydrogenation catalysts in the flow direction.
  • Radial-flow reactors are preferably used in an integrated oxidation process in which the beds (catalyst beds) of oxidation and dehydrogenation catalysts are arranged concentrically with one another and optionally separated from one another by cylindrical sieves (screens). The oxidation catalyst is then used as the inner of the two concentrically arranged approximately hollow-cylindrical Schüt ⁇ lines.
  • the unsaturated compounds obtainable in the process according to the invention for example alkenylaromatics or 1,3-alkadienes, can advantageously be plastics polymerized or used as building blocks for organic-chemical syntheses were ⁇ the.
  • SEM scanning electron microscopy
  • FIG. 3 shows scanning electron microscopy (SEM) images of the rhodia cercarbonate hydrates from their Chinese production site (Lyang Rhodia).
  • the company Rhodia has recently moved the production of the Cercarbonate Hydrate from a production site in France to a production site in China. Individual batches from the production of the French site that we examined did not show the properties of the invention in the past.
  • the measurement of the dead volume was therefore carried out with evacuated sample cooled in liquid nitrogen.
  • the weighed samples were built into the sample containers of the device. These were then evacuated at room temperature to a pressure ⁇ 2 torr and refilled with helium to a pressure> 300 torr. This was repeated five times. After the fifth evacuation, the sample containers were immersed in Deward vessels filled with liquid nitrogen so that the samples were completely submerged. It was waited five minutes. After closing the valves, the measurements were started.
  • the ball of the sample container was completely filled with the Cercarbonate hydrate in order to minimize any influence on the measurement result in view of the small BET surface areas, if possible by means of dead volume effects.
  • Example 1 (according to the invention):
  • a catalyst was prepared analogously to the comparative example using the cerium carbonate hydrate of FIG. 3 (Rhodia company).
  • Magnesium corresponding to 2.1% by weight of MgO
  • Molybdenum corresponding to 2.4% by weight MoO 3 .

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Abstract

The invention relates to a catalyst containing iron oxide(s), alkali metal compound(s) and cerium oxide(s). When producing the catalyst, cerium carbonate hydrate(s) with a BET surface area of less than 0.30 m2/g are/is used as (a) cerium constituent(s). The invention also relates to a catalyst bed, which is comprised of up to at least 25 % by weight of catalysts that contain iron oxide(s), alkali metal compound(s) and cerium oxide(s). When producing the catalysts, cerium carbonate hydrate(s) with a BET surface area of less than 0.30 m2/g are/is used as cerium constituent(s). The invention also relates to a method for dehydrogenating alkyl aromatic compounds.

Description

Katalysator enthaltend Eisenoxid(e), Alkalimetallverbindung(en) und Ceroxid(e)Catalyst containing iron oxide (s), alkali metal compound (s) and cerium oxide (s)
Beschreibungdescription
Die Erfindung betriff einen Katalysator enthaltend Eisenoxid(e), Alkalimetallverbin- dung(en) und Ceroxid(e), wobei bei der Herstellung des Katalysators als Cer- Komponente(n) Cercarbonat-Hydrat(e) mit einer BET-Oberfläche von kleiner als 0,30 m2/g eingesetzt werden. Ferner betrifft die Erfindung ein Katalysatorbett, das min¬ destens zu 25 Gew.-% aus Katalysatoren besteht, die Eisenoxid(e), Alkalimetallverbin- dung(en) und Ceroxid(e) enthalten, wobei bei der Herstellung der Katalysatoren als Cer-Komponente(n) Cercarbonat-Hydrat(e) mit einer BET-Oberfläche von kleiner als 0,30 m2/g eingesetzt werden. Darüber hinaus betrifft die Erfindung ein Verfahren zur Dehydrierung von alkylaromatischen Verbindungen.The invention relates to a catalyst containing iron oxide (s), alkali metal compound (s) and cerium oxide (s), wherein in the preparation of the catalyst as Cer component (s) Cercarbonat hydrate (s) having a BET surface area of less than 0.30 m 2 / g are used. The invention further relates to a catalyst bed which consists of at least 25% by weight of catalysts which contain iron oxide (s), alkali metal compound (s) and cerium oxide (s), in the preparation of the catalysts as cerium component (n) Cercarbonate hydrate (s) having a BET surface area of less than 0.30 m 2 / g are used. Moreover, the invention relates to a process for the dehydrogenation of alkylaromatic compounds.
EP-A 177 832 beschreibt Dehydrierkatalysatoren enthaltend Eisenoxid, Kaliumoxid, Molybdänoxid, Magnesiumoxid, Calciumoxid und Ceroxid, das unter Verwendung von kommerziell erhältlichen Ceroxid als Einsatzstoff hergestellt wird.EP-A 177 832 describes dehydrogenation catalysts comprising iron oxide, potassium oxide, molybdenum oxide, magnesium oxide, calcium oxide and cerium oxide, which is prepared using commercially available ceria as starting material.
EP-A 894 528 offenbart Dehydrierkatalysatoren, die ebenfalls Eisenoxid, Kaliumoxid, Molybdänoxid, Magnesiumoxid, Calciumoxid und Ceroxid enthalten, wobei wässrige Cernitrat-Lösung als Einsatzstoff verwendet wird. Die Verwendung von Cernitrat als Einsatzstoff hat jedoch den Nachteil, dass bei der Kalzinierung des Katalysators Stick¬ oxide freigesetzt werden.EP-A 894 528 discloses dehydrogenation catalysts which also contain iron oxide, potassium oxide, molybdenum oxide, magnesium oxide, calcium oxide and cerium oxide using aqueous cerium nitrate solution as the feedstock. However, the use of cerium nitrate as starting material has the disadvantage that nitrogen oxides are liberated during the calcination of the catalyst.
DE-A 101 54 718 beschreibt Katalysatoren enthaltend Eisenoxid, Kaliumoxid, Molyb¬ dänoxid, Magnesiumoxid, Calciumoxid und Ceroxid, das unter Verwendung von Cer- carbonat-Hydrat hergestellt wird.DE-A 101 54 718 describes catalysts comprising iron oxide, potassium oxide, molybdenum oxide, magnesium oxide, calcium oxide and cerium oxide, which is prepared using cerium carbonate hydrate.
In einem Übersichtsartikel von Trovarelli et al. „The utilization of ceria in industrial cata- lysis" wird die Bedeutung der Cer-Dotierung von Styrol-Katalysatoren herausgestellt. Ceroxide werden in der Regel in einer Menge von 5 bis 60 Gew.-% als Carbonate, Oxide, Nitrate oder Hydroxide eingesetzt. Es wird beschrieben, dass Cer durch Polari¬ sierung der Fe-O Bindung und Behinderung der Reaktion von Fe3+ zu Fe3O4 die Aktivi¬ tät und Stabilität der K-Fe-Phasen erhöht. Vermutlich spiele Cer ferner eine Rolle in dem in der Dehydrierung involvierten Redox-Zyklus. Die meisten publizierten Erklärun¬ gen über den Beitrag der Cer-Dotierung beruhen allerdings auf Hypothesen und der Einfluss der Cer-Verbindungen - sowohl bei der Herstellung des Katalysators als auch bei der Dehydrierung - ist weitgehend ungeklärt.In a review article by Trovarelli et al. The importance of the cerium doping of styrene catalysts is emphasized in "The utilization of ceria in industrial catalysis." Cerium oxides are generally used in an amount of 5 to 60% by weight as carbonates, oxides, nitrates or hydroxides. it is described that by cerium Polari¬ tion of the Fe-O bond and obstruction of reaction of Fe 3+ to Fe 3 O 4 ty the Aktivi¬ and increased stability of the K-Fe phases. probably also play a role in the cerium However, most of the published explanations about the contribution of the cerium doping are based on hypotheses and the influence of the cerium compounds-both in the preparation of the catalyst and in the dehydrogenation-is largely unexplained.
Somit besteht, trotz der vielseitig im Stand der Technik beschriebenen Katalysatorzu¬ sammensetzungen, weiterhin Verbesserungs- und Forschungsbedarf, insbesondere in Hinblick auf den Einfluss der Dotierungen auf den Umsatz und die Selektivität bei der Dehydrierung von alkylaromatischen Verbindungen.Thus, despite the versatile catalyst compositions described in the prior art, there is still room for improvement and research, in particular in With regard to the influence of the dopants on the conversion and the selectivity in the dehydrogenation of alkylaromatic compounds.
Die Aufgabe der Erfindung war es demnach, einen Katalysator zur Dehydrierung von alkylaromatischen Verbindungen aufzuzeigen, der einen verbesserten Alkylaromaten- Umsatz bei verbesserter oder gleichbleibender Alkenylaromaten-Selektivität aufweist. Ferner bestand die Aufgabe darin, bei gleicher oder verbesserter Aktivität die Benzol- Selektivität zu reduzieren.The object of the invention was therefore to show a catalyst for the dehydrogenation of alkylaromatic compounds, which has improved alkylaromatic conversion with improved or constant alkenyl aromatic selectivity. Furthermore, the object was to reduce the benzene selectivity for the same or improved activity.
Eine geringere Benzol-Selektivität führt wegen der damit parallel reduzierten Bildung von insbesondere Ethylen und Kohlendioxid in der Regel zu einer reduzierten Dehyd- riergasmenge. Dies ist insbesondere bei Styrol-Anlagen mit begrenzter Vakuum- Kompressorleistung von Bedeutung.Lower benzene selectivity generally leads to a reduced amount of dehydrogenation gas because of the parallel reduced formation of, in particular, ethylene and carbon dioxide. This is particularly important in styrene plants with limited vacuum compressor performance of importance.
Die Aufgabe wurde gelöst mit Hilfe eines Katalysators enthaltend Eisenoxid(e), Alkali- verbindung(en) und Ceroxid(e), wobei bei der Herstellung des Katalysators als Cer- Komponente(n) Cercarbonat-Hydrat(e) mit einer BET-Oberfläche von kleiner als 0,30 m2/g eingesetzt werden.The object has been achieved with the aid of a catalyst comprising iron oxide (s), alkali compound (s) and cerium oxide (e), in which case the preparation of the catalyst as cerium component (s) comprises cercarbonate hydrate (e) having a BET surface area be used of less than 0.30 m 2 / g.
Die BET-Oberfläche des Einsatzstoffes Cercarbonat-Hydrat liegt bevorzugt bei kleiner 0,25 m2/g, insbesondere liegt die BET-Oberfläche der Cercarbonat-Hydrate bei 0,01 bis 0,20 m2/g. Eine geeignete Methode zur Messungen der BET-Oberfläche wird un¬ tenstehend beschrieben.The BET surface area of the starting material cercarbonate hydrate is preferably less than 0.25 m 2 / g, in particular, the BET surface area of the cercarbonate hydrates is from 0.01 to 0.20 m 2 / g. A suitable method for measuring the BET surface area is described below.
Der Schwefelgehalt des erfindungsgemäß eingesetzten Cercarbonat-Hydrats liegt vor¬ teilhaft unter 100 Gew.-ppm, insbesondere unter 20 Gew.-ppm.The sulfur content of the cercarbonate hydrate used according to the invention is advantageously less than 100 ppm by weight, in particular less than 20 ppm by weight.
In Fig. 3 sind beispielhaft scanning-electron-microscopy (SEM)-Aufnahmen von erfin¬ dungsgemäß eingesetzten Cercarbonat-Hydrate der Firma Rhodia gezeigt. Fig 1. (Wilhelm Priem GmbH & Co KG) und Fig. 2 (Treibacher Auermet) zeigen Cercarbonat- Hydrate aus dem Stand der Technik.FIG. 3 shows, by way of example, scanning electron microscopy (SEM) images of rhodia cercarbonate hydrates used according to the invention. Fig. 1 (Wilhelm Priem GmbH & Co. KG) and Fig. 2 (Treibacher Auermet) show prior art bicarbonate hydrates.
Die Oberflächen der erfindungsgemäß eingesetzten Cercarbonat-Hydrate weisen im Vergleich zu den im Stand der Technik verwendeten Cercarbonat-Hydraten, größere Kristalle und insbesondere einen deutlich reduzierten Anteil von kleineren aufgewach¬ senen Kristallen auf.The surfaces of the cercarbonate hydrates used according to the invention have, in comparison with the cercarbonate hydrates used in the prior art, larger crystals and in particular a significantly reduced proportion of smaller crystals grown on.
Die Eigenschaften eines kristallisierten Feststoffs, wie beispielsweise Kristallgröße und folglich BET-Oberfläche, können im wesentlichen durch Kristallisationsbedingungen nach verschiedenen dem Fachmann bekannten Methoden eingestellt werden. Cercarbonat-Hydrat ist ein pastöser Feststoff mit schwankendem Wassergehalt, vor¬ teilhaft weist das erfindungsgemäß einzusetzende Cercarbonat-Hydrat eine Zusam¬ mensetzung von ungefähr (Ce)2(CO3)3 • 8H2O und eine XRD-Struktur analog Lanthanit (Gmelin Handbook Rare Earth A7 S.191) auf. Die Verwendung stärker entwässerter Cercarbonate, insbesondere kommerziell verfügbarer sogenannter trockener Cercar- bonate, ist weniger bevorzugt und führt im Allgemeinen zu Katalysatoren mit vermin¬ derten Performance-Eigenschaften.The properties of a crystallized solid, such as crystal size and hence BET surface area, can be substantially adjusted by crystallization conditions by various methods known to those skilled in the art. Cercarbonate hydrate is a pasty solid with varying water content. Advantageously, the cercarbonate hydrate to be used according to the invention has a composition of approximately (Ce) 2 (CO 3 ) 3 .8H 2 O and an XRD structure analogous to lanthanite (Gmelin Handbook Rare Earth A7 p.191). The use of more highly dehydrated cerium carbonates, in particular commercially available so-called dry cerium carbonates, is less preferred and generally leads to catalysts with reduced performance properties.
Cercarbonat-Hydrat kann von zahlreichen Anbietern bezogen werden, beispielsweise von den Firmen Treibacher Auermet Produktions GmbH in Österreich, der Wilhelm Priem GmbH & Co KG in Deutschland oder der Firma Rhodia in Frankreich. Die BET- Oberfläche der Cercarbonat-Hydrate ist sehr unterschiedlich und liegt bei 0,38 m2/g (Wilhelm Priem GmbH & Co KG), bei 0,35 m2/g (Treibacher Auermet) und bei 0,18 m2/g (Rhodia).Cercarbonate hydrate can be obtained from numerous suppliers, for example from Treibacher Auermet Produktions GmbH in Austria, Wilhelm Priem GmbH & Co. KG in Germany or Rhodia in France. The BET surface area of the cercarbonate hydrates varies widely and is 0.38 m 2 / g (Wilhelm Priem GmbH & Co. KG), 0.35 m 2 / g (Treibacher Auermet) and 0.18 m 2 / g. g (Rhodia).
Vorteilhaft werden Katalysatoren verwendet, bei deren Herstellung als Cer-Kompo- nente mindestens 25 Gew.-% Cercarbonat-Hydat mit einer BET-Oberfläche von kleiner als 0,30 m2/g eingesetzt werden. Die verbleibenden bis zu 75 Gew.-% können Cercar¬ bonat-Hydrate mit einer höhreren BET-Oberfläche sein oder andere Cer-Verbindungen wie beispielsweise Cer-Nitrate, -Oxide oder -Hydroxide. Bevorzugt sind Katalysatoren, bei deren Herstellung als Cer-Komponente mindestens 30 Gew.-%, insbesondere min¬ destens 50 Gew.-%, besonders bevorzugt ausschließlich Cercarbonat-Hydrat mit einer BET-Oberfläche von kleiner als 0,30 m2/g eingesetzt werden.Advantageously, catalysts are used whose preparation as cerium component at least 25 wt .-% ceric carbonate hydrate with a BET surface area of less than 0.30 m 2 / g are used. The remaining up to 75 wt .-% may be Cercar¬ carbonate hydrates with a higher BET surface area or other cerium compounds such as cerium nitrates, oxides or hydroxides. Preference is given to catalysts whose preparation as cerium component at least 30 wt .-%, in particular min¬ least 50 wt .-%, more preferably exclusively Cercarbonat hydrate having a BET surface area of less than 0.30 m 2 / g used become.
Die Erfindung betrifft ferner Katalysatorbetten, die zu mindestens 25 Gew.-% aus erfin¬ dungsgemäßen Katalysator bestehen. Vorteilhaft bestehen die Katalysatorbetten aus mindestens 30 Gew.-%, bevorzugt mindestens 50 Gew.-% aus erfindungsgemäßen Katalysatoren. Die erfindungsgemäßen Katalysatoren können gleichmäßig über das Katalysatorbett verteilt oder an einem oder mehreren Orten konzentriert sein. Bevor- zugt werden die erfindungsgemäßen Katalysatoren gleichmäßig über das gesamte Dehydrier-Katalysatorbett verteilt eingesetzt, insbesondere ohne Verwendung eines weiteren Dehydrierkatalysators aus dem Stand der Technik.The invention further relates to catalyst beds which consist of at least 25% by weight of catalyst according to the invention. Advantageously, the catalyst beds consist of at least 30% by weight, preferably at least 50% by weight, of catalysts according to the invention. The catalysts of the invention may be evenly distributed over the catalyst bed or concentrated at one or more locations. Preferably, the catalysts according to the invention are used uniformly distributed over the entire dehydrogenation catalyst bed, in particular without the use of a further dehydrogenation catalyst from the prior art.
Der erfindungsgemäße Katalysator eignet sich insbesondere zur Dehydrierung von Kohlenwasserstoffen, die mindestens eine gesättigte funktionelle Gruppe aufweisen, beispielsweise Alkenen zu den entsprechenden 1 ,3-Alkadienen, bevorzugt alkylaroma- tischen Verbindungen zu den entsprechenden alkenylaromatischen Verbindungen. Als alkylaromatische Verbindungen eignen sich alle aromatischen und heteroaromatischen Alkylverbindungen, bevorzugt sind solche, in denen der Alkylrest unverzweigt oder ver- zweigt ist und zwei bis sechs C-Atome enthält. Als aromatische Reste eignen sich ein-, zwei- oder dreikernige, bevorzugt ein- oder zweikernige, besonders bevorzugt einker¬ nige Aromaten. Beispielhaft seien Isopropylbenzol (Cumol), Ethylbenzol, 1 ,1-Diphenyl- benzol und 1 ,2-Diphenylethan (Bibenzyl), bevorzugt Isopropylbenzol (Cumol), Ethyl- benzol und 1 ,1-Diphenylbenzol, besonders bevorzugt Ethylbenzol genannt. Als hetero¬ aromatische Reste eignen sich ein-, zwei- oder dreikernige, bevorzugt ein- oder zwei¬ kernige, besonders bevorzugt einkernige Fünfring-Heteroaromaten mit ein bis drei Stickstoffatomen und/oder einem Sauerstoff- oder Schwefeiatom, ein-, zwei- oder drei¬ kernige, bevorzugt ein- oder zweikernige, besonders bevorzugt einkernige Sechsring- Heteroaromaten mit ein bis drei Stickstoffatome als Heteroatome, insbesondere Pyridi- ne, wie 2-Ethylpyridin, 3-Ethylpyridin, 4-Ethylpyridin und 5-EthyI-2-methylpyridin, be¬ vorzugt 2-Ethylpyridin und 5-Ethyl-2-methylpyridin.The catalyst according to the invention is particularly suitable for the dehydrogenation of hydrocarbons which have at least one saturated functional group, for example alkenes to the corresponding 1,3-alkadienes, preferably alkylaromatic compounds to the corresponding alkenylaromatic compounds. Suitable alkylaromatic compounds are all aromatic and heteroaromatic alkyl compounds, preference is given to those in which the alkyl radical is unbranched or branched and contains two to six C atoms. Suitable aromatic radicals are mono-, di- or trinuclear, preferably mono- or binuclear, particularly preferably einker¬ nige aromatics. Examples are isopropylbenzene (cumene), ethylbenzene, 1, 1-diphenyl benzene and 1,2-diphenylethane (bibenzyl), preferably isopropylbenzene (cumene), ethylbenzene and 1,1-diphenylbenzene, more preferably ethylbenzene. Suitable heteroaromatic radicals are mono-, di- or trinuclear, preferably mononuclear or dinuclear, particularly preferably mononuclear, five-membered heteroaromatic compounds having one to three nitrogen atoms and / or one oxygen atom or one sulfur atom, one, two or three ¬ Ripe, preferably mono- or binuclear, particularly preferably mononuclear, six-membered heteroaromatic having one to three nitrogen atoms as heteroatoms, in particular pyridines, such as 2-ethylpyridine, 3-ethylpyridine, 4-ethylpyridine and 5-ethyl-2-methylpyridine, be ¬ preferably 2-ethylpyridine and 5-ethyl-2-methylpyridine.
Beispielsweise sei die Dehydrierung von Ethylbenzol zu Styrol, von Cumol zu α- Methyl-Styrol, von Buten zu Butadien und von Isopenten zu Isopentadien (Isopren) genannt.For example, the dehydrogenation of ethylbenzene to styrene, of cumene to α-methyl-styrene, of butene to butadiene and of isopentene to isopentadiene (isoprene) may be mentioned.
Die erfindungsgemäßen Katalysatoren enthalten neben Eisenoxid(en), Alkalimetallver- bindung(en), bevorzugt Kaliumverbindung(en) wie beispielsweise Kaliumoxid, typi¬ scherweise eine Reihe von Promotoren in Abhängigkeit von ihrem Einsatzgebiet. Als Promotoren für einen Dehydrierungskatalysatoren eignen sich neben Cer-Verbin- dungen vorteilhaft Verbindungen von Calcium, Magnesium, Molybdän, Wolfram, Chrom und Titan. Das Gewichtsverhältnis von Kalium (berechnet als K2O) zu Eisenoxid (berechnet als Fe2O3) beträgt in der Regel 0,01 :1 bis 2:1 , bevorzugt von 0,1 :1 bis 1:1. Bevorzugt enthalten die Katalysatoren darüber hinaus weitere Promotoren (berechnet als Oxide) in einem Gewichtsverhältnis zum Eisenoxid von 0,01 :1 bis 1:1, bevorzugt von 0,02:1 bis 0,5:1.In addition to iron oxide (s), alkali metal compound (s), preferably potassium compound (s) such as, for example, potassium oxide, the catalysts according to the invention typically contain a number of promoters, depending on their field of use. Suitable promoters for a dehydrogenation catalyst are, in addition to cerium compounds, advantageously compounds of calcium, magnesium, molybdenum, tungsten, chromium and titanium. The weight ratio of potassium (calculated as K 2 O) to iron oxide (calculated as Fe 2 O 3 ) is generally from 0.01: 1 to 2: 1, preferably from 0.1: 1 to 1: 1. In addition, the catalysts preferably contain further promoters (calculated as oxides) in a weight ratio to the iron oxide of from 0.01: 1 to 1: 1, preferably from 0.02: 1 to 0.5: 1.
Der erfindungsgemäße Katalysator weist insbesondere folgende Zusammensetzung auf:The catalyst according to the invention has in particular the following composition:
Eisen, entsprechend 40 - 90 Gew.-% Fe2O3, Kalium, entsprechend 1 - 40 Gew.-% als K2O,Iron, corresponding to 40-90% by weight of Fe 2 O 3 , potassium, corresponding to 1-40% by weight as K 2 O,
Cer, entsprechend 1 - 25 Gew.-% Ce2O4, insbesondere 5 - 15 Gew.-% Ce2O4,Cerium, corresponding to 1 to 25% by weight of Ce 2 O 4 , in particular 5 to 15% by weight of Ce 2 O 4 ,
Magnesium, entsprechend 0 - 10 Gew.-% MgO,Magnesium, corresponding to 0-10% by weight of MgO,
Calcium, entsprechend 0 - 10 Gew.-% CaO,Calcium, corresponding to 0-10% by weight CaO,
Wolfram, entsprechend 0 - 10 Gew.-% WO3, Molybdän, entsprechend 0 - 10 Gew.-% MoO3,Tungsten, corresponding to 0-10% by weight of WO 3 , molybdenum, corresponding to 0-10% by weight of MoO 3 ,
Vanadium, entsprechend 0 - 10 Gew.-% V2O5 wobei sich die genannten Komponenten auf 100 Gew.-% addieren.Vanadium, corresponding to 0 - 10 wt .-% V 2 O 5 wherein said components add up to 100 wt .-%.
Zur Herstellung der erfindungsgemäßen Katalysatoren können als Einsatzstoffe Ver- bindungen der Promotoren, wie sie im fertigen Katalysator vorliegen, eingesetzt wer¬ den, oder Verbindungen, die sich während des Herstellungsprozess in Verbindungen, wie sie im fertigen Katalysator vorliegen, umwandeln. Den Einsatzstoffen können auch Hilfsstoffe zugesetzt werden, um die Verarbeitbarkeit, die mechanische Festigkeit oder die Porenstruktur zu verbessern. Beispiele für solche Stoffe sind Kartoffelstärke, Zellu¬ lose, Stearinsäure, Graphit und/oder Portland-Zement. Die Einsatzstoffe können direkt in einem Mischer, Kneter oder vorzugsweise einem Mix-Muller gemischt werden. Fer- ner können die Einsatzstoffe auch in einer Sprühmaische aufgeschlämmt und in einem Sprühtrockner zu einem Sprühpulver verarbeitet werden. Die Einsatzstoffe werden vorzugsweise in einem Mix-Muller oder Kneter unter Zugabe von Wasser zu einer extrudierbaren Masse verarbeitet. Die extrudierbare Masse wird anschließend extru- diert, getrocknet und kalziniert. Bevorzugte Strangformen umfassen Extrudate mit 2 bis 10 mm Durchmesser, insbesondere 2,5 bis 6 mm. Der Querschnitt der Extrudate kann rund oder in anderen Formen ausgeführt sein. Besonders bevorzugt sind Extrudate mit rotationssymmetrischem Querschnitt, insbesondere mit einem Durchmesser von 2 bis 4 mm, bevorzugt von 3 mm, sowie Extrudate mit einem sternförmigen oder solche mit einem zahnradförmigen ("toothed-wheel") Querschnitt, insbesondere mit Durchmes- sem von 3 bis 7, bevorzugt 3,5 mm, 4,5 mm oder 6 mm. Alternativ zu einer Extrusion kann die Formgebung der Katalysatoren auch durch eine Tablettierung erfolgen. Die extrudierten oder gegebenenfalls tablettierten Katalysatorformkörper werden anschlie¬ ßend in der Regel getrocknet und einer Kalzinierung unterzogen. Die Trocknung wird vorzugsweise auf einem Bandtrockner bei Temperaturen zwischen 100 und 2000C durchgeführt. Die Kalzinierung wird vorzugsweise in einem Drehrohr bei Temperaturen zwischen 500 und 10000C, bevorzugt zwischen 700 und 1000°C, insbesondere zwi¬ schen 800 und 9500C, und besonders bevorzugt zwischen 850 und 9000C durchge¬ führt. Insbesondere bei der Kalzinierung im besonders bevorzugten Temperaturbereich wandeln sich carbonathaltige Einsatzstoffe in Oxide um. Kalium- und Eisenoxid bilden im besonders bevorzugten Temperaturbereich typischerweise gemischte Kaliumferrit- Kristallstrukturen aus.To prepare the catalysts according to the invention, the starting materials used can be compounds of the promoters present in the finished catalyst, or compounds which convert during the preparation process into compounds present in the finished catalyst. The starting materials can also Additives may be added to improve processability, mechanical strength or pore structure. Examples of such substances are potato starch, celluloses, stearic acid, graphite and / or Portland cement. The starting materials can be mixed directly in a mixer, kneader or preferably a Mix-Muller. Furthermore, the starting materials can also be slurried in a spray mixture and processed in a spray dryer to form a spray powder. The starting materials are preferably processed in a Mix-Muller or kneader with the addition of water to form an extrudable mass. The extrudable mass is then extruded, dried and calcined. Preferred strand forms comprise extrudates of 2 to 10 mm in diameter, in particular 2.5 to 6 mm. The cross-section of the extrudates may be round or in other forms. Particularly preferred are extrudates with rotationally symmetrical cross section, in particular with a diameter of 2 to 4 mm, preferably of 3 mm, as well as extrudates with a star-shaped or those with a gear-toothed ("toothed-wheel") cross section, in particular with a diameter of 3 to 7, preferably 3.5 mm, 4.5 mm or 6 mm. As an alternative to extrusion, the shaping of the catalysts can also be carried out by tableting. The extruded or optionally tabletted shaped catalyst bodies are then usually dried and subjected to calcining. The drying is preferably carried out on a belt dryer at temperatures between 100 and 200 0 C. The calcination is preferably in a rotary kiln at temperatures between 500 and 1000 0 C, preferably between 700 and 1000 ° C, in particular zwi¬ rule 800 and 950 0 C, and particularly preferably 850 to 900 0 C durchge leads. Particularly in the calcination in the particularly preferred temperature range, carbonate-containing feedstocks convert to oxides. Potassium and iron oxides typically form mixed potassium ferrite crystal structures in the most preferred temperature range.
Die Erfindung wird im folgenden am Beispiel des Verfahrens zur Dehydrierung von Ethylbenzol zu Styrol im Detail erläutert.The invention is explained in detail below using the example of the process for the dehydrogenation of ethylbenzene to styrene.
Die Dehydrierung von Kohlenwasserstoffen kann nach allen dem Fachmann bekann¬ ten Verfahren durchgeführt werden. Bevorzugt wird die Dehydrierung von Alkylaroma- ten zu Alkenylaromaten in adiabaten oder isothermen Verfahren, insbesondere in adiabaten Verfahren, durchgeführt. Die Reaktion wird in der Regel auf mehrere in Rei- he geschaltete Reaktoren, vorzugsweise Radialstromreaktoren, verteilt. Bevorzugt sind zwei bis vier Reaktoren in Reihe geschaltet. In jedem Reaktor befindet sich ein Fest¬ bett mit Dehydrierkatalysatoren.The dehydrogenation of hydrocarbons can be carried out by all methods known to the person skilled in the art. The dehydrogenation of alkylaromatics to alkenylaromatics is preferably carried out in adiabatic or isothermal processes, in particular in adiabatic processes. The reaction is generally distributed to several reactors in series, preferably radial flow reactors. Preferably, two to four reactors are connected in series. In each reactor is a Fest¬ bed with dehydrogenation catalysts.
Bei der Dehydrierung von Ethylbenzol zu Styrol, wie sie heute in der Regel in soge- nannten adiabaten Verfahren mehrstufig ausgeübt wird, wird typischerweise Ethylben¬ zol zusammen mit Wasserdampf, vorteilhaft in einer Menge von kleiner 30 Gew.-% bezogen auf Ethylbenzol, auf Temperaturen um 5000C mittels eines Wärmetauschers erhitzt und direkt vor dem Eintritt in den ersten Reaktor mit überhitztem Wasserdampf aus einem Dampfüberhitzer gemischt, so dass die gewünschte Eintrittstemperatur im ersten Reaktor üblicherweise zwischen 600 und 650°C liegt. Das Massen-Verhältnis Wasserdampf (Gesamtwasserdampf) zu Ethylbenzol liegt bei Eintritt in die Schüttung des Dehydrierungskatalysators im ersten Reaktor vorteilhaft bei 0,7:1 bis 2,5:1. Bevor¬ zugt wird bei einem Wasserdampf/Ethylbenzol-Verhältnis von 0,75:1 bis 1 ,8:1 gearbei¬ tet, insbesondere 0,8:1 bis 1 ,5:1. Das Verfahren wird bevorzugt bei reduziertem Druck betrieben, typische Reaktordrücke liegen im Bereich von 300 bis 1000 mbar. Die Raumgeschwindigkeit (LHSV = liquid hourly space velocity) bezogen auf das aktive Volumen der Betten (also das Volumen der Betten abzüglich etwaiger nicht oder kaum durchströmter Totzonen) mit Dehydrierkatalysator liegt in der Regel bei 0,2 bis 0,7 1/h, bevorzugt 0,3 bis 0,6 1/h und insbesondere 0,32 bis 0,58 1/h. Die vorzugsweise hohl- zylinderförmig angeordneten Katalysatorbetten (Radialstromreaktoren) werden von innen nach außen durchströmt.In the dehydrogenation of ethylbenzene to styrene, as is generally practiced today in multi-stage processes in so-called adiabatic processes, ethylbenzene is typically heated to temperatures together with steam, advantageously in an amount of less than 30% by weight, based on ethylbenzene around 500 0 C by means of a heat exchanger heated and mixed directly before entering the first reactor with superheated steam from a steam superheater, so that the desired inlet temperature in the first reactor is usually between 600 and 650 ° C. The mass ratio of water vapor (total steam) to ethylbenzene when entering the bed of the dehydrogenation catalyst in the first reactor is advantageously 0.7: 1 to 2.5: 1. It is preferred to use a steam / ethylbenzene ratio of 0.75: 1 to 1.8: 1, in particular 0.8: 1 to 1.5: 1. The process is preferably operated at reduced pressure, typical reactor pressures are in the range of 300 to 1000 mbar. The space velocity (LHSV = liquid hourly space velocity) based on the active volume of the beds (ie the volume of the beds less any dead or hardly flown dead zones) with dehydrogenation catalyst is usually 0.2 to 0.7 1 / h, preferably 0.3 to 0.6 l / h and in particular 0.32 to 0.58 l / h. The preferably hollow-cylindrical catalyst beds (radial flow reactors) are flowed through from the inside to the outside.
Vor Eintritt in den nächsten Reaktor wird das Reaktionsgemisch vorteilhaft über einen Wärmetauscher mittels überhitztem Dampf erneut auf Temperaturen von üblicherweise 600 und 6500C gebracht. Bevorzugt sollte der Druck am Ausgang des letzten Reaktors nicht mehr als 700 mbar, besonders bevorzugt nicht mehr als 600 mbar und insbeson- dere nicht mehr als 500 mbar betragen.Before entering the next reactor, the reaction mixture is advantageously brought back to temperatures of usually 600 and 650 0 C via a heat exchanger by means of superheated steam. Preferably, the pressure at the outlet of the last reactor should not be more than 700 mbar, more preferably not more than 600 mbar and in particular not more than 500 mbar.
Alternativ kann an Stelle des Wärmetauschers am Eingang des zweiten und gegebe¬ nenfalls folgende Reaktoren auch eine Schüttung eines Oxidationskatalysators mit Sauerstoffzufuhr zur Verbrennung einer Teilmenge des im vorangegangenen Reaktor gebildeten Wasserstoffs eingerichtet sein, wie sie beispielsweise in der deutschen An¬ meldung mit dem Anmelde-Aktenzeichen 102004015800.2 beschrieben ist. Bevorzugt ist in einem solchen Fall mit partieller Wasserstoffverbrennung ist eine Anordnung von drei oder mehreren in Reihe angeordneten Dehydrierungsreaktoren, wobei das Oxida- tionsverfahren vorteilhaft in dem in Strömungsrichtung zweiten Reaktor und gegebe- nenfalls folgenden Dehydrierungsreaktoren ist. Das Volumenverhältnis der Schüttun¬ gen von Oxidationskatalysator und Dehydrierkatalysator pro Reaktor beträgt in der Regel 0,1 :1 bis 1:1. Bevorzugt ist bei einem integrierten Oxidationskatalysator dieser in Strömungsrichtung vor den Dehydrierungskatalysatoren angeordnet. Bevorzugt bei einem integrierten Oxidationsverfahren werden Radialstromreaktoren verwendet, bei denen die Schüttungen (Katalysatorbetten) von Oxidations- und Dehydrierungskataly¬ satoren konzentrisch ineinander angeordnet und gegebenenfalls durch zylindrische Siebe (Screens) von einander getrennt sind. Der Oxidationskatalysator wird dann als innere der beiden konzentrisch angeordneten annähernd hohlzylinderförmigen Schüt¬ tungen eingesetzt.Alternatively, instead of the heat exchanger at the inlet of the second and optionally following reactors, a bed of an oxidation catalyst with oxygen supply for combustion of a subset of the hydrogen formed in the previous reactor can be set up, as for example in the German An¬ message with the application file number 102004015800.2 is described. In such a case with partial hydrogen combustion, preference is given to an arrangement of three or more dehydrogenation reactors arranged in series, the oxidation process advantageously being in the second reactor in the direction of flow and, if appropriate, the following dehydrogenation reactors. The volume ratio of the Schüttun¬ conditions of oxidation catalyst and dehydrogenation catalyst per reactor is generally 0.1: 1 to 1: 1. In the case of an integrated oxidation catalyst, this is preferably arranged upstream of the dehydrogenation catalysts in the flow direction. Radial-flow reactors are preferably used in an integrated oxidation process in which the beds (catalyst beds) of oxidation and dehydrogenation catalysts are arranged concentrically with one another and optionally separated from one another by cylindrical sieves (screens). The oxidation catalyst is then used as the inner of the two concentrically arranged approximately hollow-cylindrical Schüt¬ lines.
Die bei dem erfindungsgemäßen Verfahren erhältlichen ungesättigten Verbindungen, beispielsweise Alkenylaromaten oder 1 ,3-Alkadiene, können vorteilhaft zu Kunststoffen polymerisiert oder als Bausteine für organisch-chemische Synthesen eingesetzt wer¬ den.The unsaturated compounds obtainable in the process according to the invention, for example alkenylaromatics or 1,3-alkadienes, can advantageously be plastics polymerized or used as building blocks for organic-chemical syntheses wer¬ the.
Fig. 1 zeigt scanning-electron-microscopy (SEM)-Aufnahmen vom Cercarbonat- Hydraten der Firma Wilhelm Priem GmbH & Co KG.1 shows scanning electron microscopy (SEM) images of cercarbonate hydrates from Wilhelm Priem GmbH & Co KG.
Fig. 2 zeigt scanning-electron-microscopy (SEM)-Aufnahmen vom Cercarbonat- Hydraten der Firma Treibacher Auermet Produktions GmbH.2 shows scanning electron microscopy (SEM) images of cercarbonate hydrates from Treibacher Auermet Produktions GmbH.
Fig. 3 zeigt scanning-electron-microscopy (SEM)-Aufnahmen vom Cercarbonat- Hydraten der Firma Rhodia von deren chinesischem Produktionsstandort (Lyang Rhodia). Die Firma Rhodia hat die Produktion des Cercarbonat-Hydrats erst in jüngerer Zeit von einem Produktionsstandort in Frankreich auf einen Produktionsstandort in China verlagert. Einzelne, von uns untersuchte Chargen aus der Produktion des fran- zösischen Standortes, zeigten in der Vergangenheit nicht die erfindungsgemäßen Ei¬ genschaften.FIG. 3 shows scanning electron microscopy (SEM) images of the rhodia cercarbonate hydrates from their Chinese production site (Lyang Rhodia). The company Rhodia has recently moved the production of the Cercarbonate Hydrate from a production site in France to a production site in China. Individual batches from the production of the French site that we examined did not show the properties of the invention in the past.
Beispiel:Example:
Tabelle 1 : Cercarbonat-Hydrate verschiedener HerstellerTable 1: Cercarbonate hydrates from different manufacturers
Figure imgf000009_0001
Figure imgf000010_0001
Figure imgf000009_0001
Figure imgf000010_0001
* siehe beschriebene Bestimmung der BET-Oberfläche* see described BET surface design
Bestimmung der BET-Oberfläche:Determination of the BET surface area:
Um die BET-Oberfläche von Proben zu bestimmen, die sich wie Cercarbonat-Hydrate beim Trocknen verändern würden, muss auf eine Trocknung verzichtet werden.In order to determine the BET surface area of samples that would change like cercarbonate hydrates during drying, no drying is necessary.
Die Messung des Totvolumens erfolgte deshalb bei evakuierter in flüssigem Stickstoff eingekühlter Probe.The measurement of the dead volume was therefore carried out with evacuated sample cooled in liquid nitrogen.
Hierzu wurden die eingewogenen Proben in den Probenbehältnissen des Geräts ein¬ gebaut. Anschließend wurden diese bei Raumtemperatur bis zu einem Druck < 2 torr evakuiert und mit Helium bis zu einem Druck > 300 torr wieder aufgefüllt. Dies wurde fünfmal wiederholt. Nach dem fünften Evakuieren wurden die Probenbehältnisse in mit flüssigem Stickstoff gefüllten Deward-Gefäßen eingetaucht, so dass die Proben voll¬ ständig eingetaucht waren. Es wurde fünf Minuten gewartet. Nach Schließen der Venti¬ le wurden die Messungen gestartet.For this purpose, the weighed samples were built into the sample containers of the device. These were then evacuated at room temperature to a pressure <2 torr and refilled with helium to a pressure> 300 torr. This was repeated five times. After the fifth evacuation, the sample containers were immersed in Deward vessels filled with liquid nitrogen so that the samples were completely submerged. It was waited five minutes. After closing the valves, the measurements were started.
Gerät: ASAP 2400 der Fa. MicromeriticsDevice: ASAP 2400 from Micromeritics
Zelle: Kugel ca. 30 mm DurchmesserCell: ball about 30 mm in diameter
Einwaage: Die Kugel des Probenbehältnisses wurde vollständig mit dem Cercarbo- nat-Hydrat gefüllt, um eine Beeinflussung des Mesergebnisses ange¬ sichts der geringen BET-Oberflächen möglichst durch Totvolumeneffekte zu minimieren.Weighing: The ball of the sample container was completely filled with the Cercarbonate hydrate in order to minimize any influence on the measurement result in view of the small BET surface areas, if possible by means of dead volume effects.
Vergleichsbeispiel (entsprechend dem Beispiel 8 der DE-A 101 54 718):Comparative Example (corresponding to Example 8 of DE-A 101 54 718):
Eine durch Aufschlämmung von 420 g Kaliumcarbonat (Pottasche), 516 g Cercarbo- nat-Hydrat (40 Gew.-% Cergehalt: Mischung aus Cercarbonat-Hydraten mit einer BET von 0,38 m2/g der Firma Wilhelm Priem GmbH & Co KG und mit einer BET von 0,35 m2/g der Firma Treibacher Auermet Produktions GmbH in einem Verhältnis von 1 :1), 74 g Ammoniumheptamolybdat, 70 g Calciumhydroxid (Weißkalkhydrat), 55 g Magnesit und 1880 g Eisenoxids (Type HP, der Fa. Thyssen-Krupp), das bei 9000C in einem Drehrohrofen vorkalziniert worden war, in 4,5 Liter Wasser hergestellte Sprüh¬ maische wurde zu einem Sprühpulver verarbeitet, unter Zusatz von Stärke in einem Kneter mit soviel Wasser (ca. 500 ml) angeteigt, dass eine extrudierbare Masse ent- stand, und zu Strängen mit 3 mm-Durchmesser extrudiert. Anschließend wurden die Stränge bei 1200C getrocknet, auf eine Länge von ungefähr 0,8 mm gebrochen und schließlich 1 h bei 8750C in einem Drehrohr kalziniert.A slurry of 420 g of potassium carbonate (potash), 516 g of cercarbonate hydrate (40 wt .-% cerium content: mixture of cercarbonate hydrates with a BET of 0.38 m 2 / g of the company Wilhelm Priem GmbH & Co KG and with a BET of 0.35 m 2 / g from Treibacher Auermet Produktions GmbH in a ratio of 1: 1), 74 g of ammonium heptamolybdate, 70 g of calcium hydroxide (hydrated lime), 55 g of magnesite and 1880 g of iron oxide (type HP, the Thyssen Krupp), which had been pre-calcined at 900 0 C in a rotary kiln Fa., mash in 4.5 liters of water Sprüh¬ produced was processed to a spray powder with the addition of starch in a kneader with sufficient water (about 500 ml ) that an extrudable mass is and extruded into strands of 3 mm diameter. Subsequently, the strands were dried at 120 0 C, broken to a length of about 0.8 mm and finally calcined for 1 h at 875 0 C in a rotary tube.
Beispiel 1 (erfindungsgemäß):Example 1 (according to the invention):
Ein Katalysator wurde analog dem Vergleichsbeispiel unter Verwendung des Cercar- bonat-Hydrats der Fig.3 (Firma Rhodia) hergestellt.A catalyst was prepared analogously to the comparative example using the cerium carbonate hydrate of FIG. 3 (Rhodia company).
Elementaranalyse des Katalysators aus dem Beispiel 1 :Elemental analysis of the catalyst from Example 1:
Kalium, entsprechend 9,3 Gew.-% als K2O,Potassium, corresponding to 9.3 wt .-% as K 2 O,
Cer, entsprechend 10,7 Gew.-% Ce2O4,Cerium, corresponding to 10.7% by weight of Ce 2 O 4 ,
Magnesium, entsprechend 2,1 Gew.-% MgO,Magnesium, corresponding to 2.1% by weight of MgO,
Calcium, entsprechend 2,2 Gew.-% CaO,Calcium, corresponding to 2.2% by weight of CaO,
Molybdän, entsprechend 2,4 Gew.-% MoO3,Molybdenum, corresponding to 2.4% by weight MoO 3 ,
Eisen, entsprechend Fe2O3, Differenz zu 100 Gew.-% (rechnerisch)Iron, corresponding to Fe 2 O 3 , difference to 100% by weight (calculated)
Dehydrierung von Ethylbenzol zu Styrol:Dehydrogenation of ethylbenzene to styrene:
In einer zweistufigen adiabaten Tests-Anlage wurden jeweils 867 ml des Katalysators aus Beispiel 1 und dem Vergleichsbeispiel unter den in Tabelle 2 angegebenen Bedin¬ gungen getestet.In a two-stage adiabatic test system, in each case 867 ml of the catalyst from Example 1 and the comparative example were tested under the conditions given in Table 2.
Tabelle 2: Versuchsbedingungen und Ergebnisse der Dehydrierung von Ethylbenzol zu StyrolTable 2: Experimental conditions and results of the dehydrogenation of ethylbenzene to styrene
Figure imgf000011_0001
Figure imgf000011_0001

Claims

Patentansprüche claims
1. Katalysator enthaltend Eisenoxid(e), Alkalimetallverbindung(en) und Ceroxid(e), wobei bei der Herstellung des Katalysators als Cer-Komponente(n) Cercarbonat- Hydrat(e) mit einer BET-Oberfläche von kleiner als 0,30 m2/g eingesetzt werden.1. Catalyst containing iron oxide (s), alkali metal compound (s) and cerium oxide (s), wherein in the preparation of the catalyst as the cerium component (s) Cercarbonat- hydrate (s) having a BET surface area of less than 0.30 m 2 / g are used.
2. Katalysator nach Anspruch 1 , wobei als Cer-Komponente(n) Cercarbonat- Hydrat(e) mit einer BET-Oberfläche von kleiner als 0,25 m2/g eingesetzt werden.2. Catalyst according to claim 1, wherein as the cerium component (s) Cercarbonat- hydrate (s) are used with a BET surface area of less than 0.25 m 2 / g.
3. Katalysator nach Anspruch 1 , wobei als Cer-Komponente(n) Cercarbonat-3. Catalyst according to claim 1, wherein as cerium component (s) Cercarbonat-
Hydrat(e) mit einer BET-Oberfläche von 0,01 bis 0,20 m2/g eingesetzt werden.Hydrate (s) are used with a BET surface area of 0.01 to 0.20 m 2 / g.
4. Katalysator nach den Ansprüchen 1 bis 3, wobei der Gehalt an Schwefel im Cer- carbonat-Hydrat kleiner als 20 Gew.-ppm ist.4. Catalyst according to claims 1 to 3, wherein the content of sulfur in the cerium carbonate hydrate is less than 20 ppm by weight.
5. Katalysator nach den Ansprüchen 1 bis 4, bei dessen Herstellung als Cer- Komponente mindestens 25 Gew.-% Cercarbonat-Hydrate mit einer BET- Oberfläche von kleiner als 0,30 m2/g eingesetzt werden.5. Catalyst according to claims 1 to 4, in whose preparation as cerium component at least 25 wt .-% Cercarbonate hydrates are used with a BET surface area of less than 0.30 m 2 / g.
6. Katalysatorbett, in dem mindestens 25 Gew.-% Katalysatoren gemäß den An¬ sprüchen 1 bis 5 vorliegen.6. Catalyst bed in which at least 25 wt .-% catalysts according to An¬ claims 1 to 5 are present.
7. Verfahren zur Dehydrierung von Kohlenwasserstoffen unter Verwendung von Katalysatoren gemäß der Ansprüche 1 bis 5.7. A process for the dehydrogenation of hydrocarbons using catalysts according to claims 1 to 5.
8. Verfahren zur Dehydrierung von Alkenen zu 1 ,3-Alkadienen unter Verwendung von Katalysatoren gemäß den Ansprüchen 1 bis 5.8. A process for the dehydrogenation of alkenes to 1, 3-alkadienes using catalysts according to claims 1 to 5.
9. Verfahren zur Dehydrierung von Ethylbenzol zu Styrol unter Verwendung von Katalysatoren gemäß den Ansprüchen 1 bis 5.9. A process for the dehydrogenation of ethylbenzene to styrene using catalysts according to claims 1 to 5.
3 Fig. Figur 1 1/33 Fig. Figure 1 1/3
Figure imgf000013_0001
Figur 2 2/3
Figure imgf000013_0001
Figure 2 2/3
Figure imgf000014_0001
Figur 3 3/3
Figure imgf000014_0001
FIG. 3 3/3
Figure imgf000015_0001
Figure imgf000015_0001
PCT/EP2005/008406 2004-08-13 2005-08-03 Catalyst containing iron oxide(s) alkali metal compound(s) and cerium oxide(s) WO2006018133A1 (en)

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Cited By (1)

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US8003837B2 (en) 2005-07-22 2011-08-23 Basf Se Catalysts for dehydrogenation and/or hydrogenation of hydrocarbons, processes for preparing the same, and uses therefor

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Publication number Priority date Publication date Assignee Title
EP0177832A2 (en) * 1984-10-11 1986-04-16 Nissan Girdler Catalyst Co., Ltd. Dehydrogenation catalysts
EP0502510A1 (en) * 1991-03-05 1992-09-09 Nissan Girdler Catalyst Co., Ltd. Alkyl aromatic hydrocarbon dehydrogenation catalyst and production method thereof
WO1996018458A1 (en) * 1994-12-14 1996-06-20 Shell Internationale Research Maatschappij B.V. Dehydrogenation catalyst and process
EP0894528A2 (en) * 1997-08-01 1999-02-03 Süd Chemie Mt S.R.L. Potassium ferrate-containing catalysts for dehydrogenating ethylbenzene to styrene
DE10154718A1 (en) * 2001-11-09 2003-05-22 Basf Ag New method for refining iron oxide, e.g. used in catalysts for the dehydration of ethylbenzene to styrene, comprises high temperature calcination

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EP0177832A2 (en) * 1984-10-11 1986-04-16 Nissan Girdler Catalyst Co., Ltd. Dehydrogenation catalysts
EP0502510A1 (en) * 1991-03-05 1992-09-09 Nissan Girdler Catalyst Co., Ltd. Alkyl aromatic hydrocarbon dehydrogenation catalyst and production method thereof
WO1996018458A1 (en) * 1994-12-14 1996-06-20 Shell Internationale Research Maatschappij B.V. Dehydrogenation catalyst and process
EP0894528A2 (en) * 1997-08-01 1999-02-03 Süd Chemie Mt S.R.L. Potassium ferrate-containing catalysts for dehydrogenating ethylbenzene to styrene
DE10154718A1 (en) * 2001-11-09 2003-05-22 Basf Ag New method for refining iron oxide, e.g. used in catalysts for the dehydration of ethylbenzene to styrene, comprises high temperature calcination

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US8003837B2 (en) 2005-07-22 2011-08-23 Basf Se Catalysts for dehydrogenation and/or hydrogenation of hydrocarbons, processes for preparing the same, and uses therefor

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