EP4213988A1 - Catalyst for ammonia synthesis with improved activity - Google Patents

Catalyst for ammonia synthesis with improved activity

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Publication number
EP4213988A1
EP4213988A1 EP21769949.5A EP21769949A EP4213988A1 EP 4213988 A1 EP4213988 A1 EP 4213988A1 EP 21769949 A EP21769949 A EP 21769949A EP 4213988 A1 EP4213988 A1 EP 4213988A1
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EP
European Patent Office
Prior art keywords
weight
catalyst
calculated
range
compounds
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
EP21769949.5A
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German (de)
French (fr)
Inventor
Rene Eckert
Benjamin-Louis Kniep
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Clariant International Ltd
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Clariant International Ltd
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Publication of EP4213988A1 publication Critical patent/EP4213988A1/en
Pending legal-status Critical Current

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Classifications

    • 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
    • B01J23/78—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 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
    • B01J23/84—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
    • B01J23/847—Vanadium, niobium or tantalum or polonium
    • B01J23/8472—Vanadium
    • 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
    • B01J23/888—Tungsten
    • B01J35/30—
    • 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
    • B01J37/0036—Grinding
    • 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
    • B01J37/0081—Preparation by melting
    • 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
    • B01J37/08—Heat treatment
    • 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
    • B01J37/16—Reducing
    • B01J37/18—Reducing with gases containing free hydrogen
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01C—AMMONIA; CYANOGEN; COMPOUNDS THEREOF
    • C01C1/00—Ammonia; Compounds thereof
    • C01C1/02—Preparation, purification or separation of ammonia
    • C01C1/04—Preparation of ammonia by synthesis in the gas phase
    • C01C1/0405—Preparation of ammonia by synthesis in the gas phase from N2 and H2 in presence of a catalyst
    • C01C1/0411—Preparation of ammonia by synthesis in the gas phase from N2 and H2 in presence of a catalyst characterised by the catalyst
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P20/00—Technologies relating to chemical industry
    • Y02P20/50—Improvements relating to the production of bulk chemicals
    • Y02P20/52—Improvements relating to the production of bulk chemicals using catalysts, e.g. selective catalysts

Definitions

  • the present invention relates to an iron-containing catalyst for ammonia synthesis, characterized in that it contains the promoters potassium, calcium and aluminum, the proportion of potassium, calculated as K2O, being 0.08 to 0.6% by weight, the proportion of calcium , calculated as CaO, is 0.8 to 2.2% by weight and the proportion of aluminum, calculated as Al2O3, is 1.0 to 2.3% by weight.
  • the invention further relates to the production of the catalyst according to the invention and a method for synthesizing ammonia using the catalyst according to the invention.
  • Ammonia is also an important building block for other areas, such as energy storage ("power-to-ammonia").
  • the catalysts used for the ammonia synthesis are predominantly selected on the basis of iron-containing catalysts.
  • the iron is usually in the form of magnetite or wustite, and the catalysts are also promoted with other elements.
  • No. 5,846,507 describes the production of an ammonia catalyst whose main phase is wustite and which was obtained by melting iron and magnetite in a resistance furnace.
  • the catalysts are produced on an industrial scale by melting the substances contained in the catalyst as a mixture in an electric arc furnace or resistance furnace, cooling the resulting melt and granulating it (Ullmann's Encyclopedia of Industrial Chemistry, 2006, Chapter 4.4.1.3., p. 35-36) .
  • CN 1235800 C describes a catalyst for the synthesis of ammonia, the 60 to 90% by weight iron (II) oxide, 7 to 35% by weight Fe (III) oxide, 0.1 to 1.8% by weight potassium oxide, 0.5 up to 4.8% by weight alumina, 0.3 to 4.7% by weight calcium oxide, 0.1 to 3.0% by weight titanium dioxide and up to 6% by weight other oxides.
  • CN 1193827 C describes a catalyst for the synthesis of ammonia which contains 65 to 92% by weight of iron(II) oxide, 6 to 22% by weight of Fe(III) oxide, 0.2 to 1.8% by weight of potassium oxide, 0.8 to
  • the catalyst described in CN 102909030 B contains 92 to 95% by weight Fe ⁇ i- X )O with x in the range from 0.043 to 0.09, 0.3 to 1.2% by weight potassium oxide, 1.5 to 2.5% by weight alumina, 1.2 bis
  • Oxygen-containing compounds such as O2 or H2O are catalyst poisons in the ammonia synthesis.
  • Fastrup, Catalysis Letters, 14 (1992), 233-239, describes the effect of the O2 concentration on the catalytic properties of the catalyst for the ammonia synthesis.
  • an iron-containing catalyst for the synthesis of ammonia which is distinguished by the presence of the promoters K, Al and Ca in specific content ranges.
  • An object of the present invention is therefore an iron-containing catalyst for the synthesis of ammonia, characterized in that it contains potassium, calculated as K2O, in the range from 0.08 to 0.6% by weight, calcium, calculated as CaO, in the range 0.8 to 2.2% by weight and aluminium, calculated as Al2O3, in the range 1.0 to 2.3% by weight contains, based on the total weight of the catalyst.
  • the content of potassium, calculated as K2O, is 0.08 to 0.6% by weight, preferably 0.1 to 0.5% by weight, more preferably 0.15 to 0.4% by weight, most preferably 0.15 to 0.3% by weight based on the total weight of the catalyst.
  • the content of calcium, calculated as CaO, is 0.8 to 2.2% by weight, preferably 0.8 to 2.0% by weight, more preferably 1.1 to
  • the aluminum content calculated as Al2O3, is 1.0 to 2.3% by weight, preferably 1.2 to 2.0% by weight, more preferably 1.3 to
  • the iron present in the catalyst according to the invention is mainly in the oxidic form, usually as magnetite or wustite or a mixture thereof.
  • the proportion of wustite in the iron compounds in the catalyst is at least 50% by weight, preferably 80% by weight, more preferably 85% by weight, more preferably 90% by weight, very particularly preferably 100% by weight.
  • other iron compounds can also be present as secondary components. The proportion of these secondary components is usually below 10% by weight, preferably below 5% by weight, particularly preferably below 1% by weight.
  • the proportion of iron compounds in the catalyst according to the invention is in the range from 80.0 to 100.0% by weight, preferably in the range from 80.0 to 99.9% by weight, more preferably in the range from 90 to 99.9% by weight , more preferably in the range of 90.0 to 97.0% by weight based on the total weight of the catalyst.
  • promoters K, Ca and Al other promoters can also be present in the catalyst.
  • the proportion of these promoters, calculated as oxides, in the catalyst according to the invention is usually 0.1 to 20.0% by weight, preferably 0.1 to 10.0% by weight, particularly preferably 1.0 to 5.0% by weight , most preferably 1.5 to 2.5% by weight based on the total weight of the catalyst.
  • the subject matter of the present invention is also a process for preparing the catalyst according to the invention.
  • the process is characterized by the following steps: a) mixing elemental iron, an iron-containing compound, compounds of the promoters potassium, aluminum, calcium and optionally compounds of other promoters to obtain a mixture b) melting the mixture obtained in step a) c) cooling the Melt from step b) to obtain a solid of the catalyst d) comminution of the solid obtained in step c), the compounds of the promoters potassium, calcium and aluminum being introduced in step a) in such a way that the catalyst resulting after step d) contains potassium, calculated as K2O, in a proportion of 0.08 to 0.6% by weight, calcium, calculated as CaO, from 0.8 to 2.2% by weight and aluminum, calculated as Al2O3 from 1.0 to 2.3 % by weight.
  • step d) The solid obtained after step d) can then be subjected to a sieving step in order to obtain catalyst granules with a desired size distribution.
  • the powdered starting compounds of elemental iron, the at least one iron-containing compound, the compounds of the promoters potassium, calcium and aluminum and optionally the compounds of other promoters are mixed together and melted in an electric arc furnace at a temperature above 1500°C brought.
  • the glowing melt is poured out and cooled until it has solidified completely.
  • the solid catalyst is crushed using jaw crushers and/or other suitable methods.
  • the comminuted catalyst can then be screened in order to obtain catalyst granules of a desired size distribution.
  • iron compounds with an oxidation state of the iron of II and/or III are suitable as iron-containing compounds.
  • Preferred compounds are Fei- x O with 0 ⁇ 1/3,
  • a mixture of elemental Fe and at least one of the compounds FeO, Fe2O3 or Fe3O4, preferably a mixture of Fe and FeO4, is used.
  • Fe(0) and FesO4 in the form of magnetite are at least partially converted into wustite, the proportion of wustite in the catalyst obtained, based on the total proportion of iron compounds, being at least 50% by weight, preferably 80% by weight, more preferably at least 85% by weight, more preferably at least 90% by weight and most preferably 100% by weight.
  • Wustite is an iron compound with the empirical formula Fei- x 0, where x can have values from 0 to less than 1/3, x is usually between 0.05 and 0.17.
  • the catalyst is particularly preferably a compound containing wustite, which is converted into Fe(0) in the reactor by reduction, usually with hydrogen.
  • the weight ratio of Fe(0) and the compound Fe1-xO, FeO, Fe2O3 or FesO4 in the mixture is in the range from 0.1 to 0.5, preferably from 0.25 to 0.4.
  • a mixture of Fe(0) and FesO4 is used in the form of magnetite, in which the weight ratio of Fe(0) and FesO4 is in the range from 0.1 to 0.5, preferably 0.25 to 0.4 lies.
  • the solids resulting from the melt contain potassium, calculated as K2O, in a proportion of 0.08 to 0.6% by weight, preferably 0.1 to 0.5% by weight, more preferably 0.15 to 0.4% by weight, most preferably 0.15 to 0.3% by weight, calcium, calculated as CaO, from 0.8 to 2.2% by weight, preferably 0.8 to 2.0% by weight, more preferably 1.1 to 1.8% by weight, even more preferably 1.2 to 1.6% by weight, most preferably 1.25 to 1.55% by weight, and aluminum calculated as Al2O3 from 1.0 to 2 3% by weight, preferably 1.2 to 2.0% by weight, more preferably 1.3 to 1.9% by weight, most preferably 1.35 to 1.75% by weight, based on the total weight of the solid.
  • the corresponding oxides, hydroxides, carbonates, hydrogen carbonates or nitrates are usually used as compounds of the promoters potassium, calcium and aluminum.
  • the corresponding oxides, carbonates or nitrates are preferably used.
  • promoters potassium, calcium and aluminum other compounds of suitable promoters can also be present in the starting mixture. These are usually compounds of the elements V, Co, Mg, the rare earths, or a combination thereof. Preferred compounds are those of elements V or Mg or a combination thereof.
  • the catalyst obtainable using the process according to the invention can then be subjected to a reduction step in order to convert the metal compounds into the corresponding metals.
  • a reduction step in order to convert the metal compounds into the corresponding metals. This can be done either at room temperature or at elevated temperature, for example a temperature in the range from 150 to 800° C., in order to convert reducible metal compounds into the corresponding metals.
  • the reduction is carried out by exposing the catalyst to a hydrogen-containing gas stream at a temperature in the range from 150 to 800° C., preferably in the range from 150 to
  • the catalysts according to the invention can be used in ammonia synthesis, in which ammonia is formed from hydrogen and nitrogen. Areas of application are on the one hand large-scale ammonia synthesis, e.g. B. according to the Haber-Bosch process. However, the catalyst can also be used for other applications, e.g. B. use the energy storage of hydrogen in the form of ammonia.
  • the reaction fluid used in the synthesis of ammonia contains nitrogen and hydrogen. Other gases which are inert under the reaction conditions, such as Ar, can also be present.
  • the reaction fluid can also contain catalyst poisons such as H2O or O2.
  • H2O and O2 in particular are suitable for oxidizing the reduced iron-containing catalyst and reducing its activity.
  • the proportion of H 2 O in the reaction fluid is usually up to 100, particularly 1 to 10 ppmv.
  • the subject matter of the present invention is also a method for synthesizing ammonia using the catalyst according to the invention.
  • the reaction fluid has up to 100 ppmv H 2 O, preferably 1 to 10 ppmv.
  • the process for synthesizing ammonia is usually characterized by a preceding step of reducing the catalyst.
  • the catalyst in the oxidic form is placed in a reactor and a stream of hydrogen and nitrogen is passed through the reactor while the reactor temperature is increased.
  • at least the iron compound is reduced, during which H2O is formed as a result of the elimination of oxygen.
  • the concentration of H2O during the reduction for a period of 12 - 120 h is in a range from 100 to 5000 ppmv, based on the gas flow after exiting the reactor.
  • the inventors have found that the catalyst according to the invention compared to such temporarily increased H2O Concentrations is more stable than catalysts known from the prior art.
  • the process for ammonia synthesis therefore comprises an upstream step of reducing the catalyst, in which the H 2 O concentration is in the range from 100 to 5000 ppmv for a period of 12-120 h, based on the gas stream after exiting the reactor.
  • the concentration of H2O can rise sharply in the meantime and noticeably damage the catalyst.
  • the concentration of H2O during the reduction for a period of 10 minutes to 8 hours is 2000 to 5000 ppmv, based on the gas stream after exiting the reactor.
  • FIG. 1 shows the powder X-ray diffraction patterns of catalysts Ia to Id, If to II and comparative catalyst Ie.
  • FIG. 2 shows the powder X-ray diffraction patterns of catalysts 2a and 2d.
  • FIG. 3 shows the yield of ammonia from catalyst 2a and from comparative catalyst 1e over the course of several cycles.
  • FIG. 4 shows the yield of ammonia from catalyst 2b and from comparative catalyst 1e as a function of the reaction temperature.
  • FIG. 5 shows an illustration of the H2O and NH3 concentrations generated by the catalytic converter 2a and the comparative catalytic converter 1e as a function of the temperature increase.
  • the crystal structures contained in the catalyst and their proportion by weight were determined by means of X-ray diffractometry and Rietveld refinement.
  • the sample was measured in a D4 Endeavor from BRUKER over a range from 5 to 90°20 (step sequence 0.020°20, 1.5 seconds measuring time per step).
  • CuKal radiation (wavelength 1.54060 ⁇ , 40 kV, 35 mA) was used as the radiation.
  • the sample plate was rotated about its axis at a speed of 30 revolutions/min.
  • the obtained diffractogram of the reflection intensities was calculated quantitatively by means of Rietveld refinement and the proportion of the respective crystal structure in the sample was determined.
  • the TOPAS software, version 6, from BRUKER was used to determine the proportion of the respective crystal structure.
  • the chemical elements were determined using TCP measurement (inductively coupled plasma) in accordance with DIN EN ISO 11885.
  • Potassium was determined by means of AAS measurement (atomic absorption spectrometry) in accordance with the “E13/E14 German Unity Method for Water Wastewater and Sludge Analysis Volume
  • the catalysts la to Id, If to 11 and the comparison catalyst le were prepared by mixing a mixture of magnetite and iron powder in a stoichiometric ratio 1:1, adding KNOs, Al2O3 and CaCOs and other metal oxide-based promoters, homogenizing and then in one Arc furnace was melted, only the proportion of KNO3 was varied for the production of the catalysts la to Id, for the comparison catalyst le the proportion of Al2O3 was also varied.
  • the proportions of K2O, Al2O3 and CaO were varied. After the mixture was completely melted, the melt was cast in a melt mold cooled and the cooled mass converted into particles by crushing the material in a jaw crusher.
  • the powder X-ray diffractograms of the individual catalysts are shown in FIG.
  • the catalysts la to Id, If to II according to the invention and the comparison catalyst le were used in a reaction for the synthesis of ammonia.
  • the catalysts according to the invention bring about a higher yield of ammonia than the comparative catalyst for which, at the latest in the 2nd cycle Catalysts 1a, 1b, 1c, If, 1g, 1h, 1j, 1k and 11 can even be observed to increase in activity with increasing cycle time.
  • Example 2 Catalyst 2a and 2b
  • the catalysts 2a and 2b were prepared according to the procedure in Example 1, the amounts of potassium, aluminum and calcium compounds being chosen such that the resulting catalysts had the following elemental composition, based on the corresponding oxides:
  • Catalyst 2a 0.25% by weight K2O, 1.46% by weight CaO, 1.64% by weight Al2O3
  • Catalyst 2b 0.31% by weight K 2 O, 1.48% by weight CaO, 1.70% by weight Al2O3
  • wustite was identified as the only iron oxide structure, as shown in FIG.
  • the reflex layers of the wustite are also shown in the diffractogram for orientation.
  • Catalyst 2a according to the invention and comparative catalyst le were used in a reaction for ammonia synthesis.
  • Catalyst 2b and comparative catalyst le were tested in a process for ammonia synthesis in which the gas mixture used also contained gaseous H2O.
  • the gas mixture used also contained gaseous H2O.
  • 120 g of catalyst sample in the form of granules with a diameter of 1.5-3.0 mm were introduced into a reactor and a gas stream consisting of nitrogen (22.5% by volume), hydrogen (67 .5% by volume, 80 ppm by volume H2O and argon (difference to 100% by volume) passed through.
  • the temperature inside the reactor was continuously increased to 520°C and kept at this temperature until reduction of the catalyst was completed.
  • the pressure was then increased to 100 bar, cooled to a temperature of 400°C and these conditions maintained for 24 hours. After the 24 hours, the concentration of ammonia formed was detected. This test was repeated for different reaction temperatures, with each temperature step being held for 8 h. The results of the ammonia concentrations are shown in FIG.
  • Catalyst 2b and comparative catalyst le were tested with regard to their reduction behavior.
  • 120 g of catalyst sample in the form of granules with diameters of 1.5-3.0 mm were introduced into a reactor and a gas stream consisting of nitrogen (22.5% by volume), hydrogen (67 .5% by volume and argon (10% by volume).
  • the temperature inside the reactor was continuously increased to 520°C and kept at this temperature until reduction of the catalyst was completed.
  • the course of the reduction is shown in FIG. Shown is a plot of the water concentration and ammonia concentration as a function of Temperature inside the catalyst bed. It is clear that the catalyst 2a according to the invention is reduced to the metallic state more quickly than the comparative catalyst le, recognizable from an earlier increase in the water concentration.
  • catalyst 2a can also convert some of the nitrogen and hydrogen contained in the gas flow into ammonia earlier. Because of the improved reduction behavior of the catalyst according to the invention, the synthesis of ammonia can also be carried out on an industrial scale with a considerable saving in time.

Abstract

The invention relates to an iron-containing catalyst for ammonia synthesis, characterised in that it contains the promoters potassium, calcium and aluminium, wherein the proportion of potassium, calculated as K2O, is 0.08 to 0.6 wt%, the proportion of calcium, calculated as CaO, is 0.8 to 2.2 wt%, and the proportion of aluminium, calculated as AI2O3, is 1.0 to 2.3 wt%. The invention also relates to the production of the catalyst according to the invention, and to a method for ammonia synthesis using the catalyst according to the invention.

Description

Katalysator für die Ammoniaksynthese mit verbesserter Aktivität Ammonia synthesis catalyst with improved activity
Die vorliegende Erfindung betrifft einen eisenhaltigen Katalysator für die Ammoniaksynthese, dadurch gekennzeichnet, dass er die Promotoren Kalium, Calcium und Aluminium enthält, wobei der Anteil an Kalium, berechnet als K2O, 0,08 bis 0, 6 Gewichts-%, der Anteil an Calcium, berechnet als CaO, 0,8 bis 2,2 Gewichts-% und der Anteil an Aluminium, berechnet als AI2O3, 1,0 bis 2,3 Gewichts-% beträgt. Weiter betrifft die Erfindung die Herstellung des erfindungsgemäßen Katalysators und ein Verfahren zur Ammoniaksynthese unter Verwendung des erfindungsgemäßen Katalysators. The present invention relates to an iron-containing catalyst for ammonia synthesis, characterized in that it contains the promoters potassium, calcium and aluminum, the proportion of potassium, calculated as K2O, being 0.08 to 0.6% by weight, the proportion of calcium , calculated as CaO, is 0.8 to 2.2% by weight and the proportion of aluminum, calculated as Al2O3, is 1.0 to 2.3% by weight. The invention further relates to the production of the catalyst according to the invention and a method for synthesizing ammonia using the catalyst according to the invention.
Die Synthese von Ammoniak aus den Elementen Wasserstoff und Stickstoff stellt eine bedeutende großindustrielle Anwendung dar, mit der sich wichtige stickstoffhaltige Folgeprodukte, insbesondere Düngemittel gewinnen lassen. Als hierbei hauptsächlich angewandtes Verfahren hat sich das Haber-Bosch-Verfahren etabliert. The synthesis of ammonia from the elements hydrogen and nitrogen represents an important large-scale industrial application, with which important nitrogen-containing secondary products, in particular fertilizers, can be obtained. The Haber-Bosch process has established itself as the main process used here.
Auch für andere Bereiche, wie z.B. die Energiespeicherung („Power- to-Ammonia") stellt Ammoniak einen wichtigen Baustein dar. Ammonia is also an important building block for other areas, such as energy storage ("power-to-ammonia").
Die für die Ammoniaksynthese eingesetzten Katalysatoren werden überwiegend auf Basis von eisenhaltigen Katalysatoren ausgewählt. Das Eisen liegt dabei üblicherweise als Magnetit oder Wüstit vor, zusätzlich sind die Katalysatoren noch mit weiteren Elementen promotiert. So beschreibt US 5,846,507 die Herstellung eines Ammoniakkatalysators, dessen Hauptphase Wüstit ist und der durch das Schmelzen von Eisen und Magnetit in einem Widerstandsofen erhalten wurde . The catalysts used for the ammonia synthesis are predominantly selected on the basis of iron-containing catalysts. The iron is usually in the form of magnetite or wustite, and the catalysts are also promoted with other elements. No. 5,846,507 describes the production of an ammonia catalyst whose main phase is wustite and which was obtained by melting iron and magnetite in a resistance furnace.
Die Herstellung der Katalysatoren erfolgt großtechnisch, indem die im Katalysator enthaltenen Stoffe als Gemisch in einem Lichtbogenofen oder Widerstandofen zum Schmelzen gebracht werden, die dabei entstehende Schmelze abgekühlt und granuliert wird (Ullmann's Encyclopedia of Industrial Chemistry, 2006, Kapitel 4.4.1.3., S. 35-36) . CN 1235800 C beschreibt einen Katalysator für die Ammoniaksynthese, der 60 bis 90 Gewichts-% Eisen ( II ) oxid, 7 bis 35 Gewichts-% Fe (III) oxid, 0,1 bis 1,8 Gewichts-% Kaliumoxid, 0,5 bis 4,8 Gewichts-% Aluminiumoxid, 0,3 bis 4,7 Gewichts-% Calciumoxid, 0,1 bis 3,0 Titandioxid und bis zu 6 Gewichts-% andere Oxide enthält. The catalysts are produced on an industrial scale by melting the substances contained in the catalyst as a mixture in an electric arc furnace or resistance furnace, cooling the resulting melt and granulating it (Ullmann's Encyclopedia of Industrial Chemistry, 2006, Chapter 4.4.1.3., p. 35-36) . CN 1235800 C describes a catalyst for the synthesis of ammonia, the 60 to 90% by weight iron (II) oxide, 7 to 35% by weight Fe (III) oxide, 0.1 to 1.8% by weight potassium oxide, 0.5 up to 4.8% by weight alumina, 0.3 to 4.7% by weight calcium oxide, 0.1 to 3.0% by weight titanium dioxide and up to 6% by weight other oxides.
In der CN 1193827 C wird ein Katalysator für die Ammoniaksynthese beschrieben, der 65 bis 92 Gewichts-% Eisen (II) oxid, 6 bis 22 Gewichts-% Fe (III) oxid, 0,2 bis 1,8 Gewichts-% Kaliumoxid, 0,8 bisCN 1193827 C describes a catalyst for the synthesis of ammonia which contains 65 to 92% by weight of iron(II) oxide, 6 to 22% by weight of Fe(III) oxide, 0.2 to 1.8% by weight of potassium oxide, 0.8 to
3.4 Gewichts-% Aluminiumoxid, 0,7 bis 3,8 Gewichts-% Calciumoxid, 0,1 bis 1,5 Gewichts-% mindestens eines Metalls des Ti, Ru, Mo, W, V oder Al, sowie 0,2 bis 2,5 mindestens eines der Oxide des Ce, Cr, Mg, Ni, W, Zr, Ti und Pd enthält. 3.4% by weight aluminum oxide, 0.7 to 3.8% by weight calcium oxide, 0.1 to 1.5% by weight of at least one metal of Ti, Ru, Mo, W, V or Al, and 0.2 to 2 ,5 contains at least one of the oxides of Ce, Cr, Mg, Ni, W, Zr, Ti and Pd.
Der in CN 102909030 B beschriebene Katalysator enthält 92 bis 95 Gewichts-% Fe<i-X)O mit x im Bereich von 0, 043 bis 0,09, 0,3 bis 1,2 Gewichts-% Kaliumoxid, 1,5 bis 2,5 Gewichts-% Aluminiumoxid, 1,2 bisThe catalyst described in CN 102909030 B contains 92 to 95% by weight Fe<i- X )O with x in the range from 0.043 to 0.09, 0.3 to 1.2% by weight potassium oxide, 1.5 to 2.5% by weight alumina, 1.2 bis
2.5 Gewichts-% Calciumoxid, 0,4 bis 1,5 Gewichts-% Magnesiumoxid sowie 0,1 bis 3,5 mindestens eines weiteren Oxids. 2.5% by weight of calcium oxide, 0.4 to 1.5% by weight of magnesium oxide and 0.1 to 3.5% of at least one further oxide.
Sauerstoffhaltige Verbindungen wie O2 oder H2O stellen in der Ammoniaksynthese Katalysatorgifte dar. So beschreibt Fastrup, Catalysis Letters, 14 (1992) , 233-239, den Effekt der O2- Konzentration auf die katalytischen Eigenschaften des Katalysators für die Ammoniaksynthese. Oxygen-containing compounds such as O2 or H2O are catalyst poisons in the ammonia synthesis. Fastrup, Catalysis Letters, 14 (1992), 233-239, describes the effect of the O2 concentration on the catalytic properties of the catalyst for the ammonia synthesis.
Es bestand weiterhin Bedarf an verbesserten eisenhaltigen Katalysatoren für die Ammoniaksynthese, die sich durch verbesserte katalytische Eigenschaften wie Aktivität, Langzeitstabilität oder Stabilität gegenüber Katalysatorgiften wie O2 oder H2O auszeichnen. There was still a need for improved iron-containing catalysts for ammonia synthesis, which are characterized by improved catalytic properties such as activity, long-term stability or stability towards catalyst poisons such as O2 or H2O.
Diese Aufgabe wird durch einen eisenhaltigen Katalysator für die Ammoniaksynthese gelöst, der sich durch die Anwesenheit der Promotoren K, Al und Ca in bestimmten Gehaltsbereichen auszeichnet. This object is achieved by an iron-containing catalyst for the synthesis of ammonia, which is distinguished by the presence of the promoters K, Al and Ca in specific content ranges.
Ein Gegenstand der vorliegenden Erfindung ist daher ein eisenhaltiger Katalysator für die Ammoniaksynthese, dadurch gekennzeichnet, dass er Kalium, berechnet als K2O, im Bereich von 0,08 bis 0, 6 Gewichts-%, Calcium, berechnet als CaO, im Bereich von 0,8 bis 2,2 Gewichts-% und Aluminium, berechnet als AI2O3, im Bereich von 1,0 bis 2,3 Gewichts-% enthält, bezogen auf das Gesamtgewicht des Katalysators. An object of the present invention is therefore an iron-containing catalyst for the synthesis of ammonia, characterized in that it contains potassium, calculated as K2O, in the range from 0.08 to 0.6% by weight, calcium, calculated as CaO, in the range 0.8 to 2.2% by weight and aluminium, calculated as Al2O3, in the range 1.0 to 2.3% by weight contains, based on the total weight of the catalyst.
Der Gehalt an Kalium, berechnet als K2O, beträgt 0,08 bis 0,6 Gewichts-%, bevorzugt 0,1 bis 0,5 Gewichts-%, bevorzugter 0,15 bis 0,4 Gewichts-%, am bevorzugtesten 0,15 bis 0,3 Gewichts-%, bezogen auf das Gesamtgewicht des Katalysators. The content of potassium, calculated as K2O, is 0.08 to 0.6% by weight, preferably 0.1 to 0.5% by weight, more preferably 0.15 to 0.4% by weight, most preferably 0.15 to 0.3% by weight based on the total weight of the catalyst.
Der Gehalt an Calcium, berechnet als CaO, beträgt 0,8 bis 2,2 Gewichts-%, bevorzugt 0,8 bis 2,0 Gewichts-%, bevorzugter 1,1 bisThe content of calcium, calculated as CaO, is 0.8 to 2.2% by weight, preferably 0.8 to 2.0% by weight, more preferably 1.1 to
1.8 Gewichts-%, noch bevorzugter 1,2 bis 1, 6 Gewichts-%, am bevorzugtesten 1,25 bis 1,55 Gewichts-%, bezogen auf das Gesamtgewicht des Katalysators. 1.8% by weight, more preferably 1.2 to 1.6% by weight, most preferably 1.25 to 1.55% by weight based on the total weight of the catalyst.
Der Gehalt an Aluminium, berechnet als AI2O3, beträgt 1,0 bis 2,3 Gewichts-%, bevorzugt 1,2 bis 2,0 Gewichts-%, bevorzugter 1,3 bisThe aluminum content, calculated as Al2O3, is 1.0 to 2.3% by weight, preferably 1.2 to 2.0% by weight, more preferably 1.3 to
1.9 Gewichts-%, am bevorzugtesten 1,35 bis 1,75 Gewichts-%, bezogen auf das Gesamtgewicht des Katalysators. 1.9% by weight, most preferably 1.35 to 1.75% by weight based on the total weight of the catalyst.
Das im erfindungsgemäßen Katalysator vorhandene Eisen liegt hauptsächlich in oxidischer Form vor, üblicherweise als Magnetit oder Wüstit oder einer Mischung davon. In einer Ausführungsform beträgt der Anteil an Wüstit an den Eisenverbindungen im Katalysator mindestens 50 Gewichts-%, bevorzugt 80 Gewichts-%, mehr bevorzugt 85 Gewichts-%, bevorzugter 90 Gewichts-%, ganz besonders bevorzugt 100 Gewichts-%. Neben den hauptsächlich vorhandenen Strukturen wie Magnetit und/oder Wüstit können auch noch andere Eisenverbindungen als Nebenbestandteile vorliegen. Der Anteil dieser Nebenbestandteile liegt üblicherweise unter 10 Gewichts-%, bevorzugt unter 5 Gewichts- %, besonders bevorzugt unter 1 Gewichts-%. The iron present in the catalyst according to the invention is mainly in the oxidic form, usually as magnetite or wustite or a mixture thereof. In one embodiment, the proportion of wustite in the iron compounds in the catalyst is at least 50% by weight, preferably 80% by weight, more preferably 85% by weight, more preferably 90% by weight, very particularly preferably 100% by weight. In addition to the structures that are mainly present, such as magnetite and/or wustite, other iron compounds can also be present as secondary components. The proportion of these secondary components is usually below 10% by weight, preferably below 5% by weight, particularly preferably below 1% by weight.
Der Anteil an Eisenverbindungen in dem erfindungsgemäßen Katalysator liegt im Bereich von 80,0 bis 100,0 Gewichts-%, bevorzugt im Bereich von 80, 0 bis 99, 9 Gewichts-%, bevorzugter im Bereich von 90 bis 99, 9 Gewichts-%, besonders bevorzugt im Bereich von 90,0 bis 97,0 Gewichts-%, bezogen auf das Gesamtgewicht des Katalysators. Neben den Promotoren K, Ca und Al können noch weitere Promotoren in dem Katalysator enthalten sein. Der Anteil dieser Promotoren, berechnet als Oxide, in dem erfindungsgemäßen Katalysator beträgt üblicherweise 0,1 bis 20,0 Gewichts-%, bevorzugt 0,1 bis 10,0 Gewichts-%, besonders bevorzugt 1,0 bis 5,0 Gewichts-%, am bevorzugtesten 1,5 bis 2,5 Gewichts-%, bezogen auf das Gesamtgewicht des Katalysators. The proportion of iron compounds in the catalyst according to the invention is in the range from 80.0 to 100.0% by weight, preferably in the range from 80.0 to 99.9% by weight, more preferably in the range from 90 to 99.9% by weight , more preferably in the range of 90.0 to 97.0% by weight based on the total weight of the catalyst. In addition to the promoters K, Ca and Al, other promoters can also be present in the catalyst. The proportion of these promoters, calculated as oxides, in the catalyst according to the invention is usually 0.1 to 20.0% by weight, preferably 0.1 to 10.0% by weight, particularly preferably 1.0 to 5.0% by weight , most preferably 1.5 to 2.5% by weight based on the total weight of the catalyst.
Gegenstand der vorliegenden Erfindung ist außerdem ein Verfahren zur Herstellung des erfindungsgemäßen Katalysators. The subject matter of the present invention is also a process for preparing the catalyst according to the invention.
Das Verfahren ist durch folgende Schritte gekennzeichnet: a) Mischen von elementarem Eisen, einer eisenhaltigen Verbindung, Verbindungen der Promotoren Kalium, Aluminium, Calcium und optional Verbindungen weiterer Promotoren zum Erhalt einer Mischung b) Schmelzen der in Schritt a) erhaltenen Mischung c) Abkühlen der Schmelze aus Schritt b) zum Erhalt eines Feststoffs des Katalysators d) Zerkleinern des in Schritt c) erhaltenen Feststoffs, wobei die Verbindungen der Promotoren Kalium, Calcium und Aluminium in Schritt a) so vorgelegt werden, dass der nach Schritt d) resultierende Katalysator Kalium, berechnet als K2O, in einem Anteil von 0,08 bis 0, 6 Gewichts-%, Calcium, berechnet als CaO, von 0,8 bis 2,2 Gewichts-% und Aluminium, berechnet als AI2O3 von 1,0 bis 2,3 Gewichts-% enthält. The process is characterized by the following steps: a) mixing elemental iron, an iron-containing compound, compounds of the promoters potassium, aluminum, calcium and optionally compounds of other promoters to obtain a mixture b) melting the mixture obtained in step a) c) cooling the Melt from step b) to obtain a solid of the catalyst d) comminution of the solid obtained in step c), the compounds of the promoters potassium, calcium and aluminum being introduced in step a) in such a way that the catalyst resulting after step d) contains potassium, calculated as K2O, in a proportion of 0.08 to 0.6% by weight, calcium, calculated as CaO, from 0.8 to 2.2% by weight and aluminum, calculated as Al2O3 from 1.0 to 2.3 % by weight.
Der nach Schritt d) erhaltene Feststoff kann anschließend noch einem Schritt der Siebung unterzogen werden, um Katalysatorgranulate mit einer gewünschten Größenverteilung zu erhalten. The solid obtained after step d) can then be subjected to a sieving step in order to obtain catalyst granules with a desired size distribution.
In einer Ausführungsform des Verfahrens werden die pulverförmigen Ausgangsverbindungen des elementaren Eisens, der mindestens einen eisenhaltigen Verbindung, der Verbindungen der Promotoren Kalium, Calcium und Aluminium und optional der Verbindungen weiterer Promotoren miteinander vermischt und in einem Lichtbogenofen bei einer Temperatur oberhalb von 1500°C zum Schmelzen gebracht. Die glühende Schmelze wird ausgegossen und abgekühlt, bis sie vollständig erstarrt ist. Der feste Katalysator wird mit Hilfe von Backenbrechern und/oder anderen geeigneten Methoden zerkleinert. Anschließend kann der zerkleinerte Katalysator gesiebt werden, um Katalysatorgranulate einer gewünschten Größenverteilung zu erhalten. In one embodiment of the process, the powdered starting compounds of elemental iron, the at least one iron-containing compound, the compounds of the promoters potassium, calcium and aluminum and optionally the compounds of other promoters are mixed together and melted in an electric arc furnace at a temperature above 1500°C brought. the glowing melt is poured out and cooled until it has solidified completely. The solid catalyst is crushed using jaw crushers and/or other suitable methods. The comminuted catalyst can then be screened in order to obtain catalyst granules of a desired size distribution.
Als eisenhaltige Verbindungen eignen sich dabei prinzipiell alle Eisenverbindungen mit einer Oxidationsstufe des Eisens von II und/oder III. Bevorzugte Verbindungen sind Fei-xO mit 0 < 1/3,In principle, all iron compounds with an oxidation state of the iron of II and/or III are suitable as iron-containing compounds. Preferred compounds are Fei- x O with 0 < 1/3,
FeO, Fe2Ü3, FesO4 und Fe oder Mischungen davon. FeO, Fe2Ü3, FesO4 and Fe or mixtures thereof.
In einer bevorzugten Ausführungsform wird eine Mischung aus elementarem Fe und mindestens einer der Verbindungen FeO, Fe2Ü3 oder Fe3Ü4, bevorzugt eine Mischung aus Fe und FesO4 eingesetzt. In einer bevorzugten Ausführungsform werden Fe(0) und FesO4 in Form von Magnetit zumindest teilweise in Wüstit umgewandelt, wobei der Anteil an Wüstit im erhaltenen Katalysator, bezogen auf den Gesamtanteil an Eisenverbindungen, mindestens 50 Gewichts-%, bevorzugt 80 Gewichts- %, mehr bevorzugt mindestens 85 Gewichts-%, bevorzugter mindestens 90 Gewichts-% und besonders bevorzugt Gewichts-100 % beträgt. In a preferred embodiment, a mixture of elemental Fe and at least one of the compounds FeO, Fe2O3 or Fe3O4, preferably a mixture of Fe and FeO4, is used. In a preferred embodiment, Fe(0) and FesO4 in the form of magnetite are at least partially converted into wustite, the proportion of wustite in the catalyst obtained, based on the total proportion of iron compounds, being at least 50% by weight, preferably 80% by weight, more preferably at least 85% by weight, more preferably at least 90% by weight and most preferably 100% by weight.
Wüstit ist eine Eisenverbindung mit der Summenformel Fei-x0, wobei x Werte von 0 bis kleiner 1/3 einnehmen kann, üblicherweise liegt x zwischen 0,05 und 0,17. Wustite is an iron compound with the empirical formula Fei- x 0, where x can have values from 0 to less than 1/3, x is usually between 0.05 and 0.17.
Besonders bevorzugt handelt es sich bei dem Katalysator um eine Verbindung beinhaltend Wüstit, die im Reaktor durch Reduktion, üblicherweise mit Wasserstoff, in Fe(0) überführt wird. The catalyst is particularly preferably a compound containing wustite, which is converted into Fe(0) in the reactor by reduction, usually with hydrogen.
In einer Ausführungsform liegt das Gewichtsverhältnis von Fe(0) und der Verbindung Fei-xO, FeO, Fe2Ü3 oder FesO4 in der Mischung im Bereich von 0,1 bis 0,5, bevorzugt 0,25 bis 0,4 vor. In einer bevorzugten Ausführungsform wird eine Mischung aus Fe(0) und FesO4 in Form von Magnetit verwendet, in dem das Gewichtsverhältnis von Fe(0) und FesO4 im Bereich von 0,1 bis 0,5, bevorzugt 0,25 bis 0,4 liegt. In one embodiment, the weight ratio of Fe(0) and the compound Fe1-xO, FeO, Fe2O3 or FesO4 in the mixture is in the range from 0.1 to 0.5, preferably from 0.25 to 0.4. In a preferred embodiment, a mixture of Fe(0) and FesO4 is used in the form of magnetite, in which the weight ratio of Fe(0) and FesO4 is in the range from 0.1 to 0.5, preferably 0.25 to 0.4 lies.
Zusätzlich zu den Eisenverbindungen liegen in der Ausgangsmischung noch Verbindungen der Promotoren Kalium, Calcium und Aluminium vor. Diese werden so vorgelegt, dass der aus der Schmelze resultierende Feststoff Kalium, berechnet als K2O, in einem Anteil von 0,08 bis 0,6 Gewichts-%, bevorzugt 0,1 bis 0,5 Gewichts-%, bevorzugter 0,15 bis 0,4 Gewichts-%, am bevorzugtesten 0,15 bis 0,3 Gewichts-%, Calcium, berechnet als CaO, von 0,8 bis 2,2 Gewichts-%, bevorzugt 0,8 bis 2,0 Gewichts-%, bevorzugter 1,1 bis 1,8 Gewichts-%, noch bevorzugter 1,2 bis 1,6 Gewichts-%, am bevorzugtesten 1,25 bis 1,55 Gewichts-%, und Aluminium, berechnet als AI2O3 von 1,0 bis 2,3 Gewichts-%, bevorzugt 1,2 bis 2,0 Gewichts-%, bevorzugter 1,3 bis 1,9 Gewichts-%, am bevorzugtesten 1,35 bis 1,75 Gewichts-% enthält bezogen auf das Gesamtgewicht des Feststoffs. In addition to the iron compounds, compounds of the promoters potassium, calcium and aluminum are also present in the starting mixture. These are presented in such a way that the solids resulting from the melt contain potassium, calculated as K2O, in a proportion of 0.08 to 0.6% by weight, preferably 0.1 to 0.5% by weight, more preferably 0.15 to 0.4% by weight, most preferably 0.15 to 0.3% by weight, calcium, calculated as CaO, from 0.8 to 2.2% by weight, preferably 0.8 to 2.0% by weight, more preferably 1.1 to 1.8% by weight, even more preferably 1.2 to 1.6% by weight, most preferably 1.25 to 1.55% by weight, and aluminum calculated as Al2O3 from 1.0 to 2 3% by weight, preferably 1.2 to 2.0% by weight, more preferably 1.3 to 1.9% by weight, most preferably 1.35 to 1.75% by weight, based on the total weight of the solid.
Als Verbindungen der Promotoren Kalium, Calcium und Aluminium werden üblicherweise die entsprechenden Oxide, Hydroxide, Carbonate, Hydrogencarbonate oder Nitrate eingesetzt. Bevorzugt werden die entsprechenden Oxide, Carbonate oder Nitrate eingesetzt. The corresponding oxides, hydroxides, carbonates, hydrogen carbonates or nitrates are usually used as compounds of the promoters potassium, calcium and aluminum. The corresponding oxides, carbonates or nitrates are preferably used.
Neben den Verbindungen der Promotoren Kalium, Calcium und Aluminium können auch noch weitere Verbindungen geeigneter Promotoren in der Ausgangsmischung vorliegen. Es handelt sich dabei üblicherweise um Verbindungen der Elemente V, Co, Mg, der seltenen Erden, oder eine Kombination davon. Bevorzugte Verbindungen sind solche der Elemente V oder Mg oder eine Kombination davon. In addition to the compounds of the promoters potassium, calcium and aluminum, other compounds of suitable promoters can also be present in the starting mixture. These are usually compounds of the elements V, Co, Mg, the rare earths, or a combination thereof. Preferred compounds are those of elements V or Mg or a combination thereof.
Der mit dem erfindungsgemäßen Verfahren erhältliche Katalysator kann anschließend einem Reduktionsschritt unterzogen werden, um die Metallverbindungen in die entsprechenden Metalle umzuwandeln. Dies kann sowohl bei Raumtemperatur oder bei erhöhter Temperatur, beispielsweise einer Temperatur im Bereich von 150 bis 800 °C erfolgen, um reduzierbare Metallverbindungen in die entsprechenden Metalle umzuwandeln. The catalyst obtainable using the process according to the invention can then be subjected to a reduction step in order to convert the metal compounds into the corresponding metals. This can be done either at room temperature or at elevated temperature, for example a temperature in the range from 150 to 800° C., in order to convert reducible metal compounds into the corresponding metals.
In einer Ausführungsform wird die Reduktion durchgeführt, indem der Katalysator einem wasserstof fhaltigen Gasstrom bei einer Temperatur im Bereich von 150 bis 800 °C, vorzugsweise im Bereich von 150 bisIn one embodiment, the reduction is carried out by exposing the catalyst to a hydrogen-containing gas stream at a temperature in the range from 150 to 800° C., preferably in the range from 150 to
600 °C, ausgesetzt wird. Die erfindungsgemäßen Katalysatoren können in der Ammoniaksynthese eingesetzt werden, bei der aus Wasserstof f und Stickstoff Ammoniak gebildet wird . Anwendungsgebiete stellen dabei einerseits die großtechnische Ammoniaksynthese , z . B . nach dem Haber-Bosch-Verfahren dar . Der Katalysator lässt sich aber auch für andere Einsat zgebiete wie z . B . die Energiespeicherung von Was serstoff in Form von Ammoniak einsetzen . 600 °C. The catalysts according to the invention can be used in ammonia synthesis, in which ammonia is formed from hydrogen and nitrogen. Areas of application are on the one hand large-scale ammonia synthesis, e.g. B. according to the Haber-Bosch process. However, the catalyst can also be used for other applications, e.g. B. use the energy storage of hydrogen in the form of ammonia.
Das in der Ammoniaksynthese eingesetzte Reaktions fluid enthält Stickstof f und Wasserstof f . Daneben können weitere, unter den Reaktionsbedingungen inerte Gase wie Ar vorliegen . In großtechnischen Prozessen zur Ammoniaksynthese können sich im Reaktions fluid auch Katalysatorgifte wie H2O oder O2 befinden . Insbesondere H2O und O2 sind geeignet , den reduzierten eisenhaltigen Katalysator zu oxidieren und dessen Aktivität zu senken . In großtechnischen Prozessen zur Ammoniaksynthese beträgt der Anteil an H2O im Reaktionsfluid üblicherweise bis zu 100 , besonders 1 bis 10 ppmv . The reaction fluid used in the synthesis of ammonia contains nitrogen and hydrogen. Other gases which are inert under the reaction conditions, such as Ar, can also be present. In large-scale ammonia synthesis processes, the reaction fluid can also contain catalyst poisons such as H2O or O2. H2O and O2 in particular are suitable for oxidizing the reduced iron-containing catalyst and reducing its activity. In large-scale processes for ammonia synthesis, the proportion of H 2 O in the reaction fluid is usually up to 100, particularly 1 to 10 ppmv.
Gegenstand der vorliegenden Erfindung ist außerdem ein Verfahren zur Ammoniaksynthese mit dem erfindungsgemäßen Katalysator . In einer Aus führungs form weist das Reaktions fluid bis zu 100 ppmv H2O auf , bevorzugt 1 bis 10 ppmv . The subject matter of the present invention is also a method for synthesizing ammonia using the catalyst according to the invention. In one embodiment, the reaction fluid has up to 100 ppmv H 2 O, preferably 1 to 10 ppmv.
Das Verfahren zur Ammoniaksynthese zeichnet sich üblicherweise durch einen vorgelagerten Schritt der Reduktion des Katalysators aus . Dazu wird der Katalysator in der oxidischen Form in einem Reaktor platziert , und ein Strom aus Wasserstof f und Stickstoff wird durch den Reaktor geleitet , während die Reaktortemperatur erhöht wird . Hierbei findet eine Reduktion mindestens der Eisenverbindung statt , bei der durch die Abspaltung von Sauerstoff H2O gebildet wird . Die Konzentration an H2O liegt während der Reduktion für eine Dauer von 12 - 120 h in einem Bereich von 100 bis 5000 ppmv, bezogen auf den Gas strom nach Austritt aus dem Reaktor . The process for synthesizing ammonia is usually characterized by a preceding step of reducing the catalyst. To do this, the catalyst in the oxidic form is placed in a reactor and a stream of hydrogen and nitrogen is passed through the reactor while the reactor temperature is increased. Here, at least the iron compound is reduced, during which H2O is formed as a result of the elimination of oxygen. The concentration of H2O during the reduction for a period of 12 - 120 h is in a range from 100 to 5000 ppmv, based on the gas flow after exiting the reactor.
Die Erfinder haben herausgefunden, dass der erfindungsgemäße Katalysator gegenüber solchen zwischenzeitlich erhöhten H2O- Konzentrationen stabiler ist als aus dem Stand der Technik bekannte Katalysatoren . The inventors have found that the catalyst according to the invention compared to such temporarily increased H2O Concentrations is more stable than catalysts known from the prior art.
In einer Ausführungsform umfasst das Verfahren zur Ammoniaksynthese daher einen vorgelagerten Schritt der Reduktion des Katalysators , bei der für einen Zeitraum von 12 - 120 h die H20-Konzentration im Bereich von 100 bis 5000 ppmv liegt , bezogen auf den Gasstrom nach Austritt aus dem Reaktor . In one embodiment, the process for ammonia synthesis therefore comprises an upstream step of reducing the catalyst, in which the H 2 O concentration is in the range from 100 to 5000 ppmv for a period of 12-120 h, based on the gas stream after exiting the reactor.
Je nach Prozessbedingungen kann die Konzentration des H2O zwischenzeitlich stark ansteigen und den Katalysator spürbar schädigen . In einer weiteren Ausführungsform beträgt daher die Konzentration an H2O während der Reduktion für eine Dauer von 10 Minuten bis 8 Stunden 2000 bis 5000 ppmv, bezogen auf den Gas strom nach Austritt aus dem Reaktor . Depending on the process conditions, the concentration of H2O can rise sharply in the meantime and noticeably damage the catalyst. In a further embodiment, therefore, the concentration of H2O during the reduction for a period of 10 minutes to 8 hours is 2000 to 5000 ppmv, based on the gas stream after exiting the reactor.
Kurze Beschreibung der Figuren Brief description of the figures
Figur 1 zeigt die Pulver-Röntgendif f raktogramme der Katalysatoren la bis Id, I f bis 11 und Vergleichskatalysator le . FIG. 1 shows the powder X-ray diffraction patterns of catalysts Ia to Id, If to II and comparative catalyst Ie.
Figur 2 zeigt die Pulver-Röntgendif f raktogramme der Katalysatoren 2a und 2d . FIG. 2 shows the powder X-ray diffraction patterns of catalysts 2a and 2d.
Figur 3 zeigt die Ausbeute an Ammoniak des Katalysators 2a und des Vergleichskatalysators le im Verlauf mehrerer Zyklen . FIG. 3 shows the yield of ammonia from catalyst 2a and from comparative catalyst 1e over the course of several cycles.
Figur 4 zeigt die Ausbeute an Ammoniak des Katalysators 2b und des Vergleichskatalysators le in Abhängigkeit der Reaktionstemperatur . FIG. 4 shows the yield of ammonia from catalyst 2b and from comparative catalyst 1e as a function of the reaction temperature.
Figur 5 zeigt eine Darstellung der durch den Katalysator 2a und den Vergleichskatalysator le erzeugten H2O- und NHs-Konzentationen in Abhängigkeit der Temperaturhöhung . FIG. 5 shows an illustration of the H2O and NH3 concentrations generated by the catalytic converter 2a and the comparative catalytic converter 1e as a function of the temperature increase.
Experimenteller Teil experimental part
Mes smethoden Pulver-Röntgendif f raktometrie mes methods Powder X-ray diffraction
Die Bestimmung der im Katalysator enthaltenen Kristallstrukturen sowie deren Gewicht santeil erfolgte mittels Röntgendiff raktometrie und Rietveld-Verf einerung . Dabei wurde die Probe in einem D4 Endeavor der Firma BRUKER über einen Bereich von 5 bis 90 ° 20 ( Schrittfolge 0 , 020 ° 20, 1 , 5 Sekunden Mes szeit pro Schritt ) gemes sen . Als Strahlung wurde CuKal-Strahlung (Wellenlänge 1 , 54060 Ä, 40 kV, 35 mA) verwendet . Der Probenteller wurde während der Mes sung mit einer Geschwindigkeit von 30 Umdrehungen/min um seine Achse gedreht . Das erhaltene Dif f raktogramm der Reflexintensitäten wurde mittels Rietveld-Verf einerung quantitativ berechnet und der Anteil der jeweiligen Kristallstruktur in der Probe bestimmt . Zur Bestimmung des Anteils der jeweiligen Kristallstruktur wurde die Software TOPAS, Version 6 , der Firma BRUKER verwendet . The crystal structures contained in the catalyst and their proportion by weight were determined by means of X-ray diffractometry and Rietveld refinement. The sample was measured in a D4 Endeavor from BRUKER over a range from 5 to 90°20 (step sequence 0.020°20, 1.5 seconds measuring time per step). CuKal radiation (wavelength 1.54060 Å, 40 kV, 35 mA) was used as the radiation. During the measurement, the sample plate was rotated about its axis at a speed of 30 revolutions/min. The obtained diffractogram of the reflection intensities was calculated quantitatively by means of Rietveld refinement and the proportion of the respective crystal structure in the sample was determined. The TOPAS software, version 6, from BRUKER was used to determine the proportion of the respective crystal structure.
Element ar analyse Element ar analysis
Die Bestimmung chemischer Elemente erfolgte mittels TCP-Mes sung ( Inductively Coupled Plasma ) nach DIN EN ISO 11885 . The chemical elements were determined using TCP measurement (inductively coupled plasma) in accordance with DIN EN ISO 11885.
Die Bestimmung von Kalium erfolgte mittels AAS-Messung (Atomabsorptionsspektrometrie ) gemäß „E13 /E14 Deutsche Einheit sverfahren zur Was ser Abwasser und Schlammuntersuchung BandPotassium was determined by means of AAS measurement (atomic absorption spectrometry) in accordance with the “E13/E14 German Unity Method for Water Wastewater and Sludge Analysis Volume
1 , 1985" . 1, 1985".
Beispiel 1 : Katalysatoren la bis Id, If bis 11 und Vergleichskatalysator le Example 1 Catalysts Ia to Id, If to II and Comparative Catalyst Ie
Die Katalysatoren la bis Id, If bis 11 und der Vergleichskatalysator le wurden hergestellt , indem eine Mischung aus Magnetit und Eisenpulver im stöchiometrischen Verhältnis 1 : 1 gemischt , mit KNOs, AI2O3 und CaCOs sowie weiteren Metalloxid-basierten Promotoren versetzt , homogenisiert und anschließend in einem Lichtbogenofen geschmolzen wurde , wobei für die Herstellung des Katalysatoren la bis Id nur der Anteil an KNO3 variiert wurde, für den Vergleichskatalysator le wurde außerdem noch der Anteil an AI2O3 variiert . Für die Herstellung der Katalysatoren I f bis 11 wurden die Anteile an K2O, AI2O3 und CaO variiert . Nachdem die Mischung komplett geschmolzen vorlag, wurde die Schmelze in einer Schmelz form abgekühlt und die abgekühlte Masse durch Zerstoßen des Materials in einem Backenbrecher zu Partikeln umgesetzt . Die Pulver- Röntgendiff raktogramme der einzelnen Katalysatoren sind in Figur 1 dargestellt und zeigen als einzige Eisenoxidstruktur die des Wüstits , dessen Reflexlagen zur Orientierung ebenfalls in demThe catalysts la to Id, If to 11 and the comparison catalyst le were prepared by mixing a mixture of magnetite and iron powder in a stoichiometric ratio 1:1, adding KNOs, Al2O3 and CaCOs and other metal oxide-based promoters, homogenizing and then in one Arc furnace was melted, only the proportion of KNO3 was varied for the production of the catalysts la to Id, for the comparison catalyst le the proportion of Al2O3 was also varied. For the preparation of the catalysts I f to 11, the proportions of K2O, Al2O3 and CaO were varied. After the mixture was completely melted, the melt was cast in a melt mold cooled and the cooled mass converted into particles by crushing the material in a jaw crusher. The powder X-ray diffractograms of the individual catalysts are shown in FIG
Dif f raktogramm dargestellt sind . Die Elementarzusammenset zungen der einzelnen Katalysatoren sind in Tabelle 1 dargestellt . Dif fractogram are shown. The elementary compositions of the individual catalysts are shown in Table 1.
Tabelle 1 : Gehalt der Promotoren K, Al und Ca in den Katalysatoren la bis 11 Table 1: Content of the promoters K, Al and Ca in the catalysts 1a to 11
Anwendungsbeispiel 1 Application example 1
Die erfindungsgemäßen Katalysatoren la bis Id, If bis 11 sowie der Vergleichskatalysator le wurden in einer Reaktion zur Ammoniaksynthese eingeset zt . The catalysts la to Id, If to II according to the invention and the comparison catalyst le were used in a reaction for the synthesis of ammonia.
Dazu wurden 7 g Katalysatorprobe in Form der Fraktion mit einem Partikeldurchmesser von 450 bis 550 Mikrometern in einen Reaktor eingefüllt , und bei einem Reaktordruck von 90 bar wurde ein Gas strom bestehend aus Stickstoff (22,5 Volumen-%) , Wasserstoff (67,5 Volumen-%) und Argon (10 Volumen-%) durchgeleitet. Die Temperatur im Reaktorinneren wurde kontinuierlich auf 520 °C erhöht und bei dieser Temperatur gehalten, bis die Reduktion des Katalysators abgeschlossen war. Anschließend wurde der Druck auf 100 bar erhöht, auf eine Temperatur von 400 °C abgekühlt und diese Bedingungen für 22 Stunden beibehalten. Nach den 22 Stunden wurde die Konzentration an gebildetem Ammoniak detektiert und die Temperatur anschließend auf 520 °C erhöht und für 14 Stunden beibehalten, um eine beschleunigte Deaktivierung des Katalysators zu bewirken. Danach wurde die vorbeschriebene Prozedur (halten der Temperatur bei 400 °C für 22 h gefolgt von Temperaturerhöhung auf 520 °C für 14 h) noch zweimal wiederholt. Die Ergebnisse der Ammoniakkonzentrationen sind in Tabelle 2 zusammengefasst. For this purpose, 7 g of catalyst sample in the form of the fraction with a particle diameter of 450 to 550 microns were introduced into a reactor, and a gas flow was established at a reactor pressure of 90 bar consisting of nitrogen (22.5% by volume), hydrogen (67.5% by volume) and argon (10% by volume). The temperature inside the reactor was continuously increased to 520°C and kept at this temperature until reduction of the catalyst was completed. The pressure was then increased to 100 bar, cooled to a temperature of 400°C and these conditions maintained for 22 hours. After the 22 hours, the concentration of ammonia formed was detected and the temperature was then increased to 520°C and maintained for 14 hours to cause accelerated deactivation of the catalyst. Thereafter, the procedure described above (keeping the temperature at 400° C. for 22 h followed by increasing the temperature to 520° C. for 14 h) was repeated twice more. Ammonia concentration results are summarized in Table 2.
Tabelle 2 : Relative Ammoniak-Raum-Zeit-Ausbeuten der Katalysatoren la bis 11 Table 2: Relative ammonia space-time yields of the catalysts 1a to 11
Anhand von Tabelle 2 erkennt man, dass die erfindungsgemäßen Katalysatoren spätestens im 2. Zyklus eine höhere Ausbeute an Ammoniak bewirken als der Vergleichskatalysator, für die Katalysatoren la, lb, 1c, If, 1g, 1h, Ij, 1k und 11 kann sogar eine Zunahme der Aktivität mit zunehmender Zyklusdauer beobachtet werden. From Table 2 it can be seen that the catalysts according to the invention bring about a higher yield of ammonia than the comparative catalyst for which, at the latest in the 2nd cycle Catalysts 1a, 1b, 1c, If, 1g, 1h, 1j, 1k and 11 can even be observed to increase in activity with increasing cycle time.
Beispiel 2: Katalysator 2a und 2b Example 2: Catalyst 2a and 2b
Die Katalysatoren 2a und 2 b wurden gemäß der Vorgehensweise in Beispiel 1 hergestellt, wobei die Mengen an Kalium-, Aluminium- und Calciumverbindungen so gewählt wurden, dass die entstehenden Katalysatoren folgende Elementarzusammensetzung, bezogen auf die entsprechenden Oxide, aufwiesen: The catalysts 2a and 2b were prepared according to the procedure in Example 1, the amounts of potassium, aluminum and calcium compounds being chosen such that the resulting catalysts had the following elemental composition, based on the corresponding oxides:
Katalysator 2a: 0,25 Gewichts-% K2O, 1,46 Gewichts-% CaO, 1,64 Gewichts-% AI2O3 Catalyst 2a: 0.25% by weight K2O, 1.46% by weight CaO, 1.64% by weight Al2O3
Katalysator 2b: 0,31 Gewichts-% K2O, 1,48 Gewichts-% CaO, 1,70 Gewichts-% AI2O3 Catalyst 2b: 0.31% by weight K 2 O, 1.48% by weight CaO, 1.70% by weight Al2O3
Als einzige Eisenoxidstruktur wurde wiederum Wüstit identifiziert, wie anhand von Figur 2 gezeigt wird. Die Reflexlagen des Wüstits sind zur Orientierung ebenfalls in dem Dif f raktogramm dargestellt. Once again, wustite was identified as the only iron oxide structure, as shown in FIG. The reflex layers of the wustite are also shown in the diffractogram for orientation.
Anwendungsbeispiel 2: Application example 2:
Der erfindungsgemäße Katalysator 2a und der Vergleichskatalysator le wurden in einer Reaktion zur Ammoniaksynthese eingesetzt. Catalyst 2a according to the invention and comparative catalyst le were used in a reaction for ammonia synthesis.
Dazu wurden 120 g Katalysatorprobe in Form eines Granulats mit Durchmessern von 1, 5-3,0 mm in einen Reaktor eingefüllt, und bei einem Reaktordruck von 90 bar wurde ein Gasstrom bestehend aus Stickstoff (22,5 Volumen-%) , Wasserstoff (67,5 Volumen-%) und Argon (10 Volumen-%) durchgeleitet. Die Temperatur im Reaktorinneren wurde kontinuierlich auf 520 °C erhöht und bei dieser Temperatur gehalten, bis die Reduktion des Katalysators abgeschlossen war. Anschließend wurde der Druck auf 100 bar erhöht, auf eine Temperatur von 400 °C abgekühlt und diese Bedingungen für 19 Stunden beibehalten. Nach den 19 Stunden wurde die Konzentration an gebildetem Ammoniak detektiert und die Temperatur anschließend auf 520 °C und einen Druck von 150 bar erhöht und für 10 Stunden beibehalten, um eine beschleunigte Deaktivierung des Katalysators zu bewirken. Danach wurde die vorbeschriebene Prozedur (halten der Temperatur bei 400 °C und 100 bar für 19 h gefolgt von Temperaturerhöhung auf 520 °C und 150 bar für 10 h) für Katalysator 2a noch elfmal, für Vergleichskatalysator le noch siebenmal wiederholt. Die Ergebnisse der Ammoniakkonzentrationen sind in Figur 3 dargestellt. For this purpose, 120 g of catalyst sample in the form of granules with a diameter of 1.5-3.0 mm were introduced into a reactor, and a gas stream consisting of nitrogen (22.5% by volume), hydrogen (67 .5% by volume and argon (10% by volume). The temperature inside the reactor was continuously increased to 520°C and kept at this temperature until reduction of the catalyst was completed. The pressure was then increased to 100 bar, cooled to a temperature of 400°C and these conditions maintained for 19 hours. After the 19 hours, the concentration of ammonia formed was detected and the temperature was then increased to 520°C and a pressure of 150 bar and maintained for 10 hours to cause accelerated deactivation of the catalyst. Then the procedure described above (keeping the temperature at 400 °C and 100 bar for 19 h followed by temperature increase to 520° C. and 150 bar for 10 h) eleven more times for catalyst 2a and seven more times for comparative catalyst le. The results of the ammonia concentrations are shown in FIG.
Anwendungsbeispiel 3: Application example 3:
Katalysator 2b und Vergleichskatalysator le wurden in einem Verfahren zur Ammoniaksynthese getestet, in dem das eingesetzte Gasgemisch zusätzlich gasförmiges H2O enthielt. Dazu wurden 120 g Katalysatorprobe in Form eines Granulats mit Durchmessern von 1,5- 3,0 mm in einen Reaktor eingefüllt, und bei einem Reaktordruck von 90 bar wurde ein Gasstrom bestehend aus Stickstoff (22,5 Volumen-%) , Wasserstoff (67,5 Volumen-%) , 80 Volumen-ppm H2O und Argon (Differenz zu 100 Volumen-%) durchgeleitet. Die Temperatur im Reaktorinneren wurde kontinuierlich auf 520 °C erhöht und bei dieser Temperatur gehalten, bis die Reduktion des Katalysators abgeschlossen war. Anschließend wurde der Druck auf 100 bar erhöht, auf eine Temperatur von 400 °C abgekühlt und diese Bedingungen für 24 Stunden beibehalten. Nach den 24 Stunden wurde die Konzentration an gebildetem Ammoniak detektiert. Dieser Test wurde für verschiedene Reaktionstemperaturen wiederholt, wobei die Temperaturstufen für jeweils 8 h gehalten wurden. Die Ergebnisse der Ammoniakkonzentrationen sind in Figur 4 dargestellt. Catalyst 2b and comparative catalyst le were tested in a process for ammonia synthesis in which the gas mixture used also contained gaseous H2O. For this purpose, 120 g of catalyst sample in the form of granules with a diameter of 1.5-3.0 mm were introduced into a reactor and a gas stream consisting of nitrogen (22.5% by volume), hydrogen (67 .5% by volume, 80 ppm by volume H2O and argon (difference to 100% by volume) passed through. The temperature inside the reactor was continuously increased to 520°C and kept at this temperature until reduction of the catalyst was completed. The pressure was then increased to 100 bar, cooled to a temperature of 400°C and these conditions maintained for 24 hours. After the 24 hours, the concentration of ammonia formed was detected. This test was repeated for different reaction temperatures, with each temperature step being held for 8 h. The results of the ammonia concentrations are shown in FIG.
Anwendungsbeispiel 4 Application example 4
Katalysator 2b und Vergleichskatalysator le wurden in Bezug auf ihr Reduktionsverhalten hin getestet. Hierzu wurden 120 g Katalysatorprobe in Form eines Granulats mit Durchmessern von 1,5- 3, 0 mm in einen Reaktor eingefüllt, und bei einem Reaktordruck von 90 bar wurde ein Gasstrom bestehend aus Stickstoff (22,5 Volumen-%) , Wasserstoff (67,5 Volumen-%) und Argon (10 Volumen-%) durchgeleitet. Die Temperatur im Reaktorinneren wurde kontinuierlich auf 520 °C erhöht und bei dieser Temperatur gehalten, bis die Reduktion des Katalysators abgeschlossen war. Der Verlauf der Reduktion ist in Figur 5 dargestellt. Dargestellt ist eine Auftragung der Wasserkonzentration und Ammoniakkonzentration in Abhängigkeit der Temperatur im Inneren der Katalysatorschüttung . Es wird deutlich, das s der erfindungsgemäße Katalysator 2a schneller in den metallischen Zustand reduziert wird als Vergleichskatalysator le, erkennbar an einem früheren Anstieg der Was serkonzentration . Aufgrund des schnelleren Erreichens des reduzierten Zustands kann Katalysator 2a auch bereits früher einen Teil des im Gasstrom enthaltenen Stickstof fs und Was serstoff s in Ammoniak umwandeln . Aufgrund des verbes serten Reduktionsverhaltens des erfindungsgemäßen Katalysators lässt sich damit die Ammoniaksynthese auch im großtechnischen Maß stab mit erheblichem Zeitgewinn durchführen . Catalyst 2b and comparative catalyst le were tested with regard to their reduction behavior. For this purpose, 120 g of catalyst sample in the form of granules with diameters of 1.5-3.0 mm were introduced into a reactor and a gas stream consisting of nitrogen (22.5% by volume), hydrogen (67 .5% by volume and argon (10% by volume). The temperature inside the reactor was continuously increased to 520°C and kept at this temperature until reduction of the catalyst was completed. The course of the reduction is shown in FIG. Shown is a plot of the water concentration and ammonia concentration as a function of Temperature inside the catalyst bed. It is clear that the catalyst 2a according to the invention is reduced to the metallic state more quickly than the comparative catalyst le, recognizable from an earlier increase in the water concentration. Because the reduced state is reached more quickly, catalyst 2a can also convert some of the nitrogen and hydrogen contained in the gas flow into ammonia earlier. Because of the improved reduction behavior of the catalyst according to the invention, the synthesis of ammonia can also be carried out on an industrial scale with a considerable saving in time.

Claims

Ansprüche Expectations
1. Eisenhaltiger Katalysator für die Ammoniaksynthese, dadurch gekennzeichnet, dass er die Promotoren Kalium, berechnet als K2O, im Bereich von 0,08 bis 0, 6 Gewichts-%, Calcium, berechnet als CaO, im Bereich von 0,8 bis 2,2 Gewichts-% und Aluminium, berechnet als AI2O3, im Bereich von 1,0 bis 2,3 Gewichts-% enthält, bezogen auf das Gesamtgewicht des Katalysators. 1. Iron-containing catalyst for ammonia synthesis, characterized in that it contains the promoters potassium, calculated as K2O, in the range from 0.08 to 0.6% by weight, calcium, calculated as CaO, in the range from 0.8 to 2 2% by weight and aluminum, calculated as Al2O3, in the range of 1.0 to 2.3% by weight based on the total weight of the catalyst.
2. Katalysator nach Anspruch 1, dadurch gekennzeichnet, dass er Kalium, berechnet als K2O, im Bereich von 0,1 bis 0,5 Gewichts- %, bevorzugter 0,15 bis 0,4 Gewichts-%, am bevorzugtesten 0,15 bis 0,3 Gewichts-%, Calcium, berechnet als CaO, im Bereich von 0,8 bis 2,0 Gewichts-%, bevorzugter 1,1 bis 1,8 Gewichts-%, noch bevorzugter 1,2 bis 1, 6 Gewichts-%, am bevorzugtesten 1,25 bis 1,55 Gewichts-% und Aluminium, berechnet als AI2O3, im Bereich von 1,2 bis 2,0 Gewichts-%, bevorzugter 1,3 bis 1,9 Gewichts-%, am bevorzugtesten 1,35 bis 1,75 Gewichts-%, enthält, bezogen auf das Gesamtgewicht des Katalysators. 2. Catalyst according to claim 1, characterized in that it contains potassium, calculated as K2O, in the range of 0.1 to 0.5% by weight, more preferably 0.15 to 0.4% by weight, most preferably 0.15 to 0.3% by weight, calcium, calculated as CaO, in the range of 0.8 to 2.0% by weight, more preferably 1.1 to 1.8% by weight, even more preferably 1.2 to 1.6% by weight %, most preferably 1.25 to 1.55% by weight and aluminum, calculated as Al2O3, in the range 1.2 to 2.0% by weight, more preferably 1.3 to 1.9% by weight, most preferably 1 .35 to 1.75% by weight based on the total weight of the catalyst.
3. Katalysator nach einem der Ansprüche 1 oder 2, wobei der Anteil an Eisenverbindungen im Bereich von 80, 0 bis 100, 0 Gewichts-%, bevorzugt im Bereich von 80,0 bis 99, 9 Gewichts-%, bevorzugter im Bereich von 90 bis 99, 9 Gewichts-%, besonders bevorzugt im Bereich von 90,0 bis 97,0 Gewichts-%, bezogen auf das Gesamtgewicht des Katalysators, liegt. 3. Catalyst according to one of claims 1 or 2, wherein the proportion of iron compounds is in the range from 80.0 to 100.0% by weight, preferably in the range from 80.0 to 99.9% by weight, more preferably in the range from 90 to 99.9% by weight, more preferably in the range from 90.0 to 97.0% by weight, based on the total weight of the catalyst.
4. Katalysator nach einem der Ansprüche 1 bis 3, wobei der Anteil an Wüstit an den Eisenverbindungen im Katalysator mindestens 50 Gewichts-%, bevorzugt 80 Gewichts-%, mehr bevorzugt 85 Gewichts-%, bevorzugter 90 Gewichts-%, ganz besonders bevorzugt 100 Gewichts-% beträgt. 4. Catalyst according to one of claims 1 to 3, wherein the proportion of wustite in the iron compounds in the catalyst is at least 50% by weight, preferably 80% by weight, more preferably 85% by weight, more preferably 90% by weight, very particularly preferably 100 % by weight.
5. Katalysator nach einem der Ansprüche 1 bis 4, wobei der Katalysator einen Anteil weiterer Promotoren, berechnet als Oxide, 0,1 bis 20,0 Gewichts-%, bevorzugt 0,1 bis 10,0 Gewichts-%, besonders bevorzugt 1,0 bis 5,0 Gewichts-%, am bevorzugtesten 1,5 bis 2,5 Gewichts-%, bezogen auf das Gesamtgewicht des Katalysators, enthält. Verfahren zur Herstellung eines Katalysators nach einem der vorhergehenden Ansprüche, durch folgende Schritte gekennzeichnet : a) Mischen von elementarem Eisen, einer eisenhaltigen Verbindung, Verbindungen der Promotoren Kalium, Aluminium, Calcium und optional Verbindungen weiterer Promotoren zum Erhalt einer Mischung b) Schmelzen der in Schritt a) erhaltenen Mischung c) Abkühlen der Schmelze aus Schritt b) zum Erhalt eines Feststoffs des Katalysators d) Zerkleinern des in Schritt c) erhaltenen Feststoffs, wobei die Verbindungen der Promotoren Kalium, Calcium und Aluminium in Schritt a) so vorgelegt werden, dass der nach Schritt d) resultierende Katalysator Kalium, berechnet als K2O, in einem Anteil von 0,08 bis 0,5. Catalyst according to one of claims 1 to 4, wherein the catalyst has a proportion of further promoters, calculated as oxides, 0.1 to 20.0% by weight, preferably 0.1 to 10.0% by weight, particularly preferably 1, 0 to 5.0% by weight, most preferably 1.5 to 2.5% by weight based on the total weight of the catalyst. Process for preparing a catalyst according to one of the preceding claims, characterized by the following steps: a) mixing elemental iron, an iron-containing compound, compounds of the promoters potassium, aluminum, calcium and optionally compounds of other promoters to obtain a mixture b) melting the in step a) mixture obtained c) cooling the melt from step b) to obtain a solid of the catalyst d) comminution of the solid obtained in step c), the compounds of the promoters potassium, calcium and aluminum being presented in step a) in such a way that the after step d) resulting catalyst potassium, calculated as K2O, in a proportion of 0.08 to 0,
6 Gewichts-%, Calcium, berechnet als CaO, von 0,8 bis 2,2 Gewichts-% und Aluminium, berechnet als AI2O3, von 1,0 bis 2,3 Gewichts-% enthält, bezogen auf das Gesamtgewicht des Katalysators. 6% by weight, calcium, calculated as CaO, from 0.8 to 2.2% by weight and aluminum, calculated as Al2O3, from 1.0 to 2.3% by weight, based on the total weight of the catalyst.
7. Verfahren nach Anspruch 6, wobei das Schmelzen in Schritt b) in einem Lichtbogenofen erfolgt. 7. The method according to claim 6, wherein the melting in step b) takes place in an electric arc furnace.
8. Verfahren nach einem der Ansprüche 6 oder 7, wobei die eisenhaltige Verbindung FeO, Fe2Ü oder FesO4 ist, bevorzugt FeaO4. 8. The method according to any one of claims 6 or 7, wherein the iron-containing compound is FeO, Fe2O or FesO4, preferably FeaO4.
9. Verfahren nach einem der Ansprüche 6 bis 8, wobei als Verbindungen der Promotoren Kalium, Calcium und Aluminium die entsprechenden Oxide, Hydroxide, Carbonate, Hydrogencarbonate oder Nitrate eingesetzt werden, bevorzugt die entsprechenden Oxide, Carbonate oder Nitrate. 9. The method according to any one of claims 6 to 8, wherein the corresponding oxides, hydroxides, carbonates, hydrogen carbonates or nitrates are used as compounds of the promoters potassium, calcium and aluminum, preferably the corresponding oxides, carbonates or nitrates.
10. Verfahren nach einem der Ansprüche 6 bis 9, wobei in Schritt a) Verbindungen der Promotoren V, Co, Mg, der seltenen Erden, oder eine Kombination davon, bevorzugt Verbindungen des V oder Mg oder eine Kombination davon, zugegeben werden. 10. The method according to any one of claims 6 to 9, wherein in step a) compounds of the promoters V, Co, Mg, the rare earths, or a combination thereof, preferably compounds of V or Mg or a combination thereof, are added.
11. Verfahren zur Ammoniaksynthese mit einem Katalysator nach einem der Ansprüche 1 bis 5. 11. A method for ammonia synthesis using a catalyst according to any one of claims 1 to 5.
12. Verfahren nach Anspruch 11, wobei das Reaktionsfluid bis zu 100 ppmv, bevorzugt 1 bis 10 ppmv gasförmiges H2O enthält. 12. The method according to claim 11, wherein the reaction fluid contains up to 100 ppmv, preferably 1 to 10 ppmv gaseous H2O.
13. Verfahren nach einem der Ansprüche 11 oder 12, wobei ein Schritt der Reduktion des Katalysators vorgelagert ist, während dem die Konzentration an H2O für eine Dauer von 12 - 120 h in einem Bereich von 100 bis 5000 ppmv liegt, bezogen auf den Strom, der den Reaktor verlassen hat. 13. The method according to any one of claims 11 or 12, wherein a step of reducing the catalyst is preceded, during which the concentration of H2O for a period of 12-120 h is in a range from 100 to 5000 ppmv, based on the stream, who left the reactor.
14. Verfahren nach Anspruch 13, wobei außerdem die Konzentration an H2O während der Reduktion für eine Dauer von14. The method according to claim 13, further comprising the concentration of H2O during the reduction for a period of
10 Minuten bis 8 Stunden 2000 bis 5000 ppmv beträgt, bezogen auf den Strom, der den Reaktor verlassen hat. 10 minutes to 8 hours is 2000 to 5000 ppmv based on the stream leaving the reactor.
17 17
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Family Cites Families (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
AT252957B (en) * 1964-10-23 1967-03-10 Chemie Linz Ag Process for the production of iron oxide catalysts
AT273173B (en) * 1967-05-29 1969-08-11 Chemie Linz Ag Process for the reduction of iron oxide catalysts for ammonia synthesis
US3951862A (en) * 1974-10-30 1976-04-20 The Lummus Company Process for the preparation of ammonia synthesis catalyst
GB2092016B (en) * 1981-01-30 1985-01-03 Lytkin Viktor Petrovich Process for producing granluated catalyst for the synthesis of ammonia
US5846507A (en) 1994-05-26 1998-12-08 Zhejiang University Of Technology Fe1-x O-based catalyst for ammonia synthesis
CN1235800C (en) 2001-10-12 2006-01-11 陈能 High-activity ferrous oxide base amonia synthesis catalyst and its preparation method
CN1193827C (en) 2002-09-26 2005-03-23 浙江工业大学 Catalyst for ultralow temperature high activity ammonia synthesis
CN101676026B (en) * 2008-09-18 2011-12-07 中国石油天然气股份有限公司 Iron ammonia synthesis catalyst and preparation method
CN102909030B (en) 2012-09-12 2015-01-28 浙江工业大学 Ferrous oxide-based ammonia synthesis catalyst
BR112019002346B1 (en) * 2016-08-08 2022-06-21 Tokyo Institute Of Technology Method for manufacturing an ammonia synthesis catalyst, metal supported material and catalyst comprising said material

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