EP1450946A1 - Cu/zn/al catalyst for methanol synthesis - Google Patents

Cu/zn/al catalyst for methanol synthesis

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Publication number
EP1450946A1
EP1450946A1 EP02805277A EP02805277A EP1450946A1 EP 1450946 A1 EP1450946 A1 EP 1450946A1 EP 02805277 A EP02805277 A EP 02805277A EP 02805277 A EP02805277 A EP 02805277A EP 1450946 A1 EP1450946 A1 EP 1450946A1
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EP
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Prior art keywords
catalyst
catalyst according
solution
salts
alkali metal
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EP02805277A
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German (de)
French (fr)
Inventor
Jürgen Ladebeck
Jürgen Koy
Tiberius Regula
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Sued Chemie IP GmbH and Co KG
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Sued Chemie AG
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    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C29/00—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring
    • C07C29/15—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring by reduction of oxides of carbon exclusively
    • C07C29/151—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring by reduction of oxides of carbon exclusively with hydrogen or hydrogen-containing gases
    • C07C29/153—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring by reduction of oxides of carbon exclusively with hydrogen or hydrogen-containing gases characterised by the catalyst used
    • C07C29/154—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring by reduction of oxides of carbon exclusively with hydrogen or hydrogen-containing gases characterised by the catalyst used containing copper, silver, gold, or compounds thereof
    • 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
    • B01J23/80—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 zinc, cadmium or mercury
    • 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
    • B01J35/00—Catalysts, in general, characterised by their form or physical properties
    • B01J35/20—Catalysts, in general, characterised by their form or physical properties characterised by their non-solid state
    • B01J35/23—Catalysts, in general, characterised by their form or physical properties characterised by their non-solid state in a colloidal state
    • 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
    • B01J35/00—Catalysts, in general, characterised by their form or physical properties
    • B01J35/30—Catalysts, in general, characterised by their form or physical properties characterised by their physical properties
    • 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
    • B01J35/00—Catalysts, in general, characterised by their form or physical properties
    • B01J35/30—Catalysts, in general, characterised by their form or physical properties characterised by their physical properties
    • B01J35/391—Physical properties of the active metal ingredient
    • B01J35/393—Metal or metal oxide crystallite size
    • 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
    • B01J35/00—Catalysts, in general, characterised by their form or physical properties
    • B01J35/60—Catalysts, in general, characterised by their form or physical properties characterised by their surface properties or porosity
    • B01J35/61—Surface area
    • B01J35/613—10-100 m2/g
    • 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
    • B01J35/00—Catalysts, in general, characterised by their form or physical properties
    • B01J35/60—Catalysts, in general, characterised by their form or physical properties characterised by their surface properties or porosity
    • B01J35/61—Surface area
    • B01J35/615—100-500 m2/g
    • 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 invention relates to a Cu / Zn / Al catalyst containing copper oxide and zinc oxide as catalytically active substances and aluminum oxide as a thermostabilizing substance.
  • the invention further relates to a process for the preparation of this catalyst and its use for the synthesis of methanol.
  • Cu / Zn / Al catalysts which catalyze the conversion of CO, C0 2 and H 2 to methanol have been known for a long time.
  • the atomic ratios between copper and zinc can vary in these known catalysts, but the copper is generally present in excess.
  • part of the zinc component can be partially replaced by calcium, magnesium and / or manganese.
  • the aluminum oxide used as a thermostabilizing substance can also partially be replaced by chromium oxide.
  • Such catalysts are known for example from DE-A 1 956 007, 2 302 658 and 2 056 612 and from US-A-4, 279, 781.
  • a corresponding catalyst for methanol synthesis is also known from EP-A-0 125 689.
  • This catalyst is characterized in that the proportion of pores with a diameter in the range from 20 to 75 ⁇ is at least 20% and the proportion of pores with a diameter of more than 75 ⁇ is at most 80%.
  • the Cu / Zn atomic ratio is between 2.8 and 3.8, preferably between 2.8 and 3.2, and the proportion of A1 2 0 3 is 8 to 12% by weight.
  • a similar catalyst for methanol synthesis is known from DE-A-44 16 425. It has a Cu / Zn atomic ratio of 2: 1 and generally consists of 50 to 75% by weight of CuO, 15 to 35% by weight of ZnO and also contains 5 to 20% by weight of A1 2 0 3 ,
  • a similar catalyst is known from JP-A-07008799. It contains about 10 to 215 parts (atomic ratio) of Zn and about 1 to 50 parts of Al or Cr per 100 parts of Cu.
  • EP-A-0 152 809 discloses a catalyst for the synthesis of alcohol mixtures containing methanol and higher alcohols, which in the form of an oxidic precursor (a) copper oxide and zinc oxide (b) aluminum oxide as a thermostabilizing substance and (c) at least one alkali carbonate or contains alkali oxide, the oxidic precursor having a proportion of pores with a diameter between 15 and 7.5 nm of 20 to 70% of the total volume, the alkali content being 13 to 130-10 "6 gram atom of alkali metal per gram of the oxidic precursor and the alumina component has been obtained from a colloidally distributed aluminum hydroxide (aluminum hydroxide sol or gel).
  • the invention is therefore based on the object of providing Cu / Zn / Al catalysts with high specific activity, selectivity and thermal stability.
  • the invention relates to a Cu / Zn / Al catalyst containing copper oxide and zinc oxide as catalytically active substances and aluminum oxide as a thermostabilizing substance, which is characterized in that the Cu / Zn atomic ratio is ⁇ 2.8, preferably between about 1, 8 and 2.7, and that the alumina component has been obtained at least partially from an aluminum hydroxide sol.
  • the proportion of the aluminum oxide component corresponds essentially to the proportion in the known catalysts.
  • the catalyst according to the invention has a higher activity in methanol synthesis, in particular at temperatures of less than 250 ° C., and a higher thermal stability than the catalyst according to EP-A-125 689, the aluminum hydroxide sol being responsible for increasing the thermal stability. This suppresses the coalescence of the copper crystallites after the reduction.
  • the aluminum oxide particles obtained from the aluminum hydroxide sol on heating probably form net-like elevations on the surface of the catalyst, between which the CuO crystallites and, after the reduction, the copper crystallites are to a certain extent in an "energy sink".
  • the zinc oxide also has a stabilizing effect in that it becomes a component of the reticulated Al 2 O 3 structure on the surface of the catalyst and thus helps to prevent the Cu crystallites from growing together after the reduction.
  • the zinc oxide also acts as a poison scavenger by reacting with the sulfur compounds contained in the feed.
  • the size of the Cu crystallites in the reduced state is preferably about 6 to 7 nm.
  • the size of the Cu crystallites was determined by means of X-ray powder diffractometry (XRD).
  • XRD X-ray powder diffractometry
  • the Cu (III) reflex in the range of ⁇ 43.3 ° 2 ⁇ was measured.
  • the full width at half maximum and the integral intensity of the reflex were calculated using the pseudo-Voigt and Lorentz profile functions.
  • the Cu crystallite size was calculated using the Scherrer function on the basis of the calculated half-width.
  • the proportion of the aluminum oxide component is preferably approximately 1 to 20% by weight, in particular approximately 5 to 20% by weight.
  • the catalyst In the oxidic state, the catalyst has a BET surface area of about 90 to 120 m 2 / g and a pore volume of about 320 to 500 m / g, preferably about 320 to 380 ⁇ n / g.
  • the BET surface area is determined using the nitrogen single-point method in accordance with DIN 66132.
  • the pore volume is determined by the mercury intrusion method based on DIN 66133.
  • a commercially available product can be used as the aluminum hydroxide sol.
  • the aluminum hydroxide sol can also be obtained by adding a little NH 4 OH to a dilute aluminum salt solution, avoiding heating in order to delay the conversion into crystalline aluminum metahydroxide (AlO (OH)).
  • boehmite ( ⁇ -AlO (OH)) or pseudoboehmite can be treated with nitric acid and the solution obtained can be diluted, the sol being formed.
  • an alkali aluminate solution can be diluted (optionally with the addition of a small amount of acid), the sol being formed.
  • the oxide catalysts are generally reduced as follows.
  • the tablets (10 g) are heated in a tubular reactor with a reducing gas (98% N 2 , 2% H 2 ) at a heating rate of 1 ° C / min from room temperature to 240 ° C.
  • the average degree of reduction of Cu is greater than 95%.
  • the invention further relates to a process for the preparation of the catalyst indicated above, which is characterized in that the corresponding hydroxocarbonates or hydroxides are obtained from a solution of Cu and Zn salts and part of the Al salts with an alkali metal carbonate or alkali metal aluminate solution precipitates, with either the solution of the Cu and Zn salts or the alkali carbonate or alkali aluminate solution containing an aluminum hydroxide sol, whereupon the precipitate obtained is separated from the precipitation solution, washed, dried, calcined and optionally reduced.
  • the corresponding nitrates are preferably used as Cu and Zn salts and the corresponding sodium compounds as alkali metal carbonates or alkali metal aluminates.
  • the precursor of the catalyst according to the invention obtained after the precipitation and drying has a lower proportion of hydrotalcite analog phase than the known catalyst, because the aluminum hydroxide sol no longer reacts with the formation of hydrotalcite.
  • a hydrotalcite analog phase is a hydrotalcite in which the magnesium is replaced by copper and zinc. Accordingly, the proportion of the malachite phase in the dried precursor is higher than in the known catalyst.
  • the malachite phase consists essentially of a basic Cu / Zn carbonate.
  • a Cu / Zn mixed oxide or a mixture of CuO and ZnO is formed in a fine distribution.
  • the hydrotalcite-analog phase forms a Cu / Al oxide phase which, after reduction, gives a catalyst with relatively high stability but less activity.
  • the catalyst obtained from the malachite phase is active but not as stable.
  • the hydrotalcite-like phase and the malachite phase can be determined by X-ray diffraction analysis of the dried precursor. These phases disappear after the thermal treatment.
  • the BET surface area also depends on the Cu / Zn atomic ratio. It is generally between about 90 and 120 m 2 / g and is therefore higher than the BET surface area of the known catalyst.
  • the pore volume also depends on the Cu / Zn atomic ratio. It is generally between about 320 and 500 mm 3 / g, preferably between about 320 and 380 mm 3 / g, and is therefore higher than in the known catalyst.
  • the invention also relates to the use of the catalyst for methanol synthesis.
  • the experiments on methanol synthesis showed that the thermal stability of the catalysts is increased as the Cu / Zn atomic ratio decreases.
  • the zinc oxide acts as a placeholder, which prevents the Cu crystallites from sintering together quickly in the reduced catalyst.
  • the size of the copper crystallites decreases during the methanol synthesis depending on the CO 2 partial pressure, ie the Cu crystallites grow more strongly at higher CO 2 partial pressures.
  • a 15.37% by weight sodium carbonate solution with a solution volume of 143 liters was prepared with distilled water (141 liters) at 50 ° C. by adding Na 2 CO 3 (25.15 kg).
  • the solution had a density of 1.154 g / ml at 38 ° C.
  • the nitrate solution (containing aluminum hydroxide sol) and the soda solution were simultaneously pumped through the mixing tube into the precipitation tank at a temperature of 74 ° C.
  • the temperature in the precipitation tank was 60 ° C, the pH about 6.5.
  • the residence time in the precipitation container was about 5 to 10 minutes.
  • the suspension is pumped continuously from the precipitation container into the aging container.
  • the suspension was heated to 70.degree.
  • the precipitation was 60 min. aged at 70 ° C
  • the color of the precipitation changes from light blue (start of aging) to green (end of aging).
  • the pH rose from 6.6 + 0.1 to 7.3 ⁇ 0.1 in the course of aging.
  • the suspension was filtered after aging.
  • the wet filter cake was slurried in distilled water and filtered again. This process was repeated until the Na content in the filter cake was ⁇ 350 ppm.
  • the filter cake was slurried to an oxide concentration of 10% by adding water and dried in a spray dryer at an inlet temperature of 275 to 280 ° C and an outlet temperature of 105 to 115 ° C.
  • the washed catalyst precursor was then calcined at 320 ° C. for 3 hours.
  • the oxidic catalyst precursor was in a tubular reactor with a reducing gas (98% N 2 ; 2% H 2 ) at a heating rate of 1 ° C / min. heated from room temperature to 240 ° C.
  • the average degree of reduction of the Cu was 85%.
  • the size of the Cu crystallites after the reduction was 6.3 nm.
  • Example 2: Cu / Zn 2.4
  • Example 1 The procedure of Example 1 was repeated with the difference that the Cu / Zn ratio used was 2.4 and the pH during the precipitation was 7.0 + 0.1. The size of the Cu crystallites after the reduction was 6.8 nm.
  • Example 2 The procedure of Example 2 was repeated with the difference that the Cu / Zn ratio used was 2.62. The size of the Cu crystallites after the reduction was 7.5 nm.
  • Solution 1 418 g of copper nitrate and 50 g of ZnO are dissolved in 1 liter of water and 148 g of 52.5% HN0 3 and then a solution of 93.8 g of A1 (N0 3 ) 3 x 9H 2 0 in 0.5 liters of water is added.
  • Solution 2 410 g of sodium carbonate were dissolved in 2 liters of water.
  • the solutions were heated separately to 68 ° C. and combined with vigorous stirring in such a way that the pH was 6.7 during the precipitation.
  • the precipitate was aged with stirring at 68 ° C. for one hour in the mother liquor. On- it was finally filtered off and washed free of sodium with water.
  • the filter cake was dried at 120 ° C and then calcined at 280 ° C for 8 hours. The calcined product was crushed and then compressed after adding 2% by weight of graphite.
  • the size of the Cu crystallites after the reduction was 8.5 nm.
  • Example 1 Example 2 Example 3 Example 4
  • the by-products and the ethanol content were also determined as a function of the operating time in order to determine the selectivity.
  • the by-products are higher hydrocarbons (C 3 to C ⁇ 0 ), alcohols (C 2 to C 5 ), ethers, esters and ketones. These are determined by gas chromatography.
  • the by-products also interfere in the ppm range if they are present in the methanol.
  • the by-products in the methanol require expensive processing (distillation) of the methanol.

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Catalysts (AREA)
  • Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
  • Low-Molecular Organic Synthesis Reactions Using Catalysts (AREA)

Abstract

A Cu/Zn/Al catalyst comprising copper oxide and zinc oxide as catalytically-effective substances and aluminium oxide as thermostabilising substance is disclosed. The catalyst is characterised in that the Cu/Zn atom ratio is < 2.8 and the aluminium oxide component is obtained from an aluminium hydroxide sol.

Description

Patentanme1düng Patentanme1düng
CU/ZN/AL - KATALYSATOR FÜR DIE METHANOLSYNTHESECU / ZN / AL - CATALYST FOR METHANOL SYNTHESIS
Beschreibungdescription
Die Erfindung betrifft einen Cu/Zn/Al-Katalysator, enthaltend Kupferoxid und Zinkoxid als katalytisch wirksame Substanzen sowie Aluminiumoxid als thermostabilisierende Substanz. Die Erfindung betrifft ferner ein Verfahren zur Herstellung dieses Katalysators sowie dessen Verwendung für die Methanolsynthese .The invention relates to a Cu / Zn / Al catalyst containing copper oxide and zinc oxide as catalytically active substances and aluminum oxide as a thermostabilizing substance. The invention further relates to a process for the preparation of this catalyst and its use for the synthesis of methanol.
Cu/Zn/Al-Katalysatoren, welche die Umsetzung von CO, C02 und H2 zu Methanol katalysieren, sind schon seit längerer Zeit bekannt. Die Atomverhältnisse zwischen Kupfer und Zink können bei diesen bekannten Katalysatoren variieren, wobei jedoch das Kupfer im allgemeinen im Uberschuss vorliegt. Ferner kann ein Teil der Zinkkomponente teilweise durch Calcium, Magnesium und/oder Mangan ersetzt sein. Das als thermostabilisierende Substanz verwendete Aluminiumoxid kann teilweise auch durch Chromoxid ersetzt sein. Derartige Katalysatoren sind beispielsweise aus den DE-A 1 956 007, 2 302 658 und 2 056 612 sowie aus der US-A-4 , 279 , 781 bekannt. Eine entsprechender Katalysator für die Methanolsynthese ist auch aus der EP-A-0 125 689 bekannt. Dieser Katalysator ist dadurch gekennzeichnet, dass der Anteil der Poren mit einem Durchmesser im Bereich von 20 bis 75Ä mindestens 20% und der Anteil der Poren mit einem Durchmesser von mehr als 75Ä höchstens 80% beträgt. Das Cu/Zn-Atomverhältnis liegt zwischen 2,8 und 3,8, vorzugsweise zwischen 2,8 und 3,2, und der Anteil an A1203 beträgt 8 bis 12 Gew.-%.Cu / Zn / Al catalysts which catalyze the conversion of CO, C0 2 and H 2 to methanol have been known for a long time. The atomic ratios between copper and zinc can vary in these known catalysts, but the copper is generally present in excess. Furthermore, part of the zinc component can be partially replaced by calcium, magnesium and / or manganese. The aluminum oxide used as a thermostabilizing substance can also partially be replaced by chromium oxide. Such catalysts are known for example from DE-A 1 956 007, 2 302 658 and 2 056 612 and from US-A-4, 279, 781. A corresponding catalyst for methanol synthesis is also known from EP-A-0 125 689. This catalyst is characterized in that the proportion of pores with a diameter in the range from 20 to 75 Å is at least 20% and the proportion of pores with a diameter of more than 75 Å is at most 80%. The Cu / Zn atomic ratio is between 2.8 and 3.8, preferably between 2.8 and 3.2, and the proportion of A1 2 0 3 is 8 to 12% by weight.
Ein ähnlicher Katalysator für die Methanolsynthese ist aus der DE-A-44 16 425 bekannt. Er hat ein Atomverhältnis Cu/Zn von 2 : 1 und besteht im Allgemeinen zu 50 bis 75 Gew.-% aus CuO, zu 15 bis 35Gew.-% aus ZnO und enthält daneben noch 5 bis 20 Gew. -% A1203.A similar catalyst for methanol synthesis is known from DE-A-44 16 425. It has a Cu / Zn atomic ratio of 2: 1 and generally consists of 50 to 75% by weight of CuO, 15 to 35% by weight of ZnO and also contains 5 to 20% by weight of A1 2 0 3 ,
Ein ähnlicher Katalysator ist aus der JP-A-07008799 bekannt. Er enthält etwa 10 bis 215 Teile (Atomverhältnis) Zn und etwa 1 bis 50 Teile AI oder Cr auf 100 Teile Cu.A similar catalyst is known from JP-A-07008799. It contains about 10 to 215 parts (atomic ratio) of Zn and about 1 to 50 parts of Al or Cr per 100 parts of Cu.
Schließlich ist aus der EP-A-0 152 809 ein Katalysator zur Synthese von Methanol und höhere Alkohole enthaltenden Alkoholgemischen bekannt, der in Form eines oxidischen Vorläufers (a) Kupferoxid und Zinkoxid (b) Aluminiumoxid als thermostabilisierende Substanz und (c) mindestens ein Alkalicarbonat bzw. Alkalioxid enthält, wobei der oxidische Vorläufer einen Anteil an Poren mit einem Durchmesser zwischen 15 und 7,5 nm von 20 bis 70% des Gesamtvolumens besitzt, der Alkaligehalt 13 bis 130-10"6 Grammatom Alkalimetall je Gramm des oxidischen Vorläufers beträgt und die Aluminiumoxidkomponente aus einem kolloidal verteilten Aluminiumhydroxid (Aluminiumhydroxid-Sol oder -Gel) erhalten worden ist. Es wurde gefunden, dass bei der Erniedrigung des Cu/Zn- Atomverhältnisses überraschende Ergebnisse im Hinblick auf spezifische Aktivität und Selektivität, insbesondere bei Temperaturen von weniger als 250°C erhalten werden können. Auch die thermische Stabilität wird verbessert. Der Erfindung liegt somit die Aufgabe zugrunde, Cu/Zn/Al-Katalysatoren mit hoher spezifischer Aktivität, Selektivität und thermischer Stabilität bereitzustellen.Finally, EP-A-0 152 809 discloses a catalyst for the synthesis of alcohol mixtures containing methanol and higher alcohols, which in the form of an oxidic precursor (a) copper oxide and zinc oxide (b) aluminum oxide as a thermostabilizing substance and (c) at least one alkali carbonate or contains alkali oxide, the oxidic precursor having a proportion of pores with a diameter between 15 and 7.5 nm of 20 to 70% of the total volume, the alkali content being 13 to 130-10 "6 gram atom of alkali metal per gram of the oxidic precursor and the alumina component has been obtained from a colloidally distributed aluminum hydroxide (aluminum hydroxide sol or gel). It was found that surprising results in terms of specific activity and selectivity, in particular at temperatures of less than 250 ° C., can be obtained when the Cu / Zn atomic ratio is lowered. Thermal stability is also improved. The invention is therefore based on the object of providing Cu / Zn / Al catalysts with high specific activity, selectivity and thermal stability.
Gegenstand der Erfindung ist ein Cu/Zn/Al-Katalysator, enthaltend Kupferoxid und Zinkoxid als katalytisch wirksame Substanzen und Aluminiumoxid als thermostabilisierende Substanz, der dadurch gekennzeichnet ist, dass das Cu/Zn-Atomverhältnis < 2,8 ist, vorzugsweise zwischen etwa 1,8 und 2,7 liegt, und dass die Aluminiumoxid-Komponente mindestens teilweise aus einem Aluminiumhydroxid-Sol erhalten worden ist. Der Anteil der Aluminiumoxid-Komponente entspricht in wesentlichen dem Anteil in den bekannten Katalysatoren.The invention relates to a Cu / Zn / Al catalyst containing copper oxide and zinc oxide as catalytically active substances and aluminum oxide as a thermostabilizing substance, which is characterized in that the Cu / Zn atomic ratio is <2.8, preferably between about 1, 8 and 2.7, and that the alumina component has been obtained at least partially from an aluminum hydroxide sol. The proportion of the aluminum oxide component corresponds essentially to the proportion in the known catalysts.
Der erfindungsgemäße Katalysator hat eine höhere Aktivität bei der Methanolsynthese, insbesondere bei Temperaturen von weniger als 250°C, sowie eine höhere thermische Stabilität als der Katalysator nach der EP-A-125 689, wobei für die Erhöhung der thermischen Stabilität das Aluminiumhydroxidsol verantwortlich ist. Dieses unterdrückt das Zusammenwachsen der Kupferkristallite nach der Reduktion. Wahrscheinlich bilden die aus dem Aluminiumhydroxidsol beim Erhitzen erhaltenen Aluminiumoxidteilchen netzförmige Erhöhungen auf der Oberfläche des Katalysators, zwischen denen sich die CuO-Kristallite und nach der Reduktion die Kupferkristallite gewisser maßen in einer "Energiesenke" befinden. Das Zinkoxid wirkt ebenfalls stabilisierend, indem es ein Bestandteil der netzförmigen Al203-Struktur auf der Oberfläche des Katalysators wird und somit dazu beiträgt, dass das Zusammenwachsen der Cu-Kristallite nach der Reduktion unter drückt wird. Außerdem wirkt das Zinkoxid als Giftfänger, indem es mit den im Einsatzmaterial enthaltenen Schwefelverbindungen reagiert .The catalyst according to the invention has a higher activity in methanol synthesis, in particular at temperatures of less than 250 ° C., and a higher thermal stability than the catalyst according to EP-A-125 689, the aluminum hydroxide sol being responsible for increasing the thermal stability. This suppresses the coalescence of the copper crystallites after the reduction. The aluminum oxide particles obtained from the aluminum hydroxide sol on heating probably form net-like elevations on the surface of the catalyst, between which the CuO crystallites and, after the reduction, the copper crystallites are to a certain extent in an "energy sink". The zinc oxide also has a stabilizing effect in that it becomes a component of the reticulated Al 2 O 3 structure on the surface of the catalyst and thus helps to prevent the Cu crystallites from growing together after the reduction. The zinc oxide also acts as a poison scavenger by reacting with the sulfur compounds contained in the feed.
Bevorzugte Ausführungsformen sind in den Unteransprüchen angegeben .Preferred embodiments are specified in the subclaims.
Insbesondere beträgt die Größe der Cu-Kristallite in reduziertem Zustand vorzugsweise etwa 6 bis 7 nm.In particular, the size of the Cu crystallites in the reduced state is preferably about 6 to 7 nm.
Die Größe der Cu-Kristallite wurde mittels Röntgen-Pulver- Diffraktometrie (XRD) bestimmt. Der Cu(lll) Reflex im Bereich von ~ 43,3°2Θ wurden vermessen. Die Halbwertsbreite und die integrale Intensität des Reflexes wurde mit der Pseudo-Voigt- und der Lorentz-Profil-Funktion berechnet. Die Cu-Kristallit- grδße wurde mit Hilfe der Scherrer-Funktion auf der Basis der berechneten Halbwertsbreite berechnet.The size of the Cu crystallites was determined by means of X-ray powder diffractometry (XRD). The Cu (III) reflex in the range of ~ 43.3 ° 2Θ was measured. The full width at half maximum and the integral intensity of the reflex were calculated using the pseudo-Voigt and Lorentz profile functions. The Cu crystallite size was calculated using the Scherrer function on the basis of the calculated half-width.
( Der Anteil der Aluminiumoxidkomponente beträgt vorzugsweise etwa 1 bis 20 Gew.-%, insbesondere etwa 5 bis 20 Gew.-%.(The proportion of the aluminum oxide component is preferably approximately 1 to 20% by weight, in particular approximately 5 to 20% by weight.
Der Katalysator hat im oxidischen Zustand eine BET-Oberflache von etwa 90 bis 120 m2/g und ein Porenvolumen von etwa 320 bis 500 m /g, vorzugsweise etwa 320 bis 380 τn /g.In the oxidic state, the catalyst has a BET surface area of about 90 to 120 m 2 / g and a pore volume of about 320 to 500 m / g, preferably about 320 to 380 τn / g.
Die BET-Oberflache wird nach der Stickstoff-Einpunktmethode in Anlehnung an DIN 66132 bestimmt. Das Porenvolumen wird nach der Quecksilber-Intrusionsmethode in Anlehnung an DIN 66133 bestimmt. Als Aluminiumhydroxidsol kann ein im Handel erhältliches Produkt verwendet werden. Das Aluminiumhydroxidsol kann aber auch dadurch erhalten werden, dass man einer verdünnten Aluminiumsalzlösung etwas NH4OH zusetzt, wobei man eine Erwärmung vermeidet, um die Umwandlung in kristallines Aluminiummeta- hydroxid (AlO(OH)) zu verzögern. Nach einer weiteren Variante kann man Boehmit (γ-AlO(OH)) oder Pseudoboehmit mit Salpetersäure behandeln und die erhaltene Lösung verdünnen, wobei das Sol gebildet wird. Nach einer weiteren Variante kann man eine Alkalialuminatlösung (gegebenenfalls unter Zusatz einer geringen Menge Säure) verdünnen, wobei das Sol gebildet wird.The BET surface area is determined using the nitrogen single-point method in accordance with DIN 66132. The pore volume is determined by the mercury intrusion method based on DIN 66133. A commercially available product can be used as the aluminum hydroxide sol. However, the aluminum hydroxide sol can also be obtained by adding a little NH 4 OH to a dilute aluminum salt solution, avoiding heating in order to delay the conversion into crystalline aluminum metahydroxide (AlO (OH)). According to a further variant, boehmite (γ-AlO (OH)) or pseudoboehmite can be treated with nitric acid and the solution obtained can be diluted, the sol being formed. According to a further variant, an alkali aluminate solution can be diluted (optionally with the addition of a small amount of acid), the sol being formed.
Die oxidischen Katalysatoren werden im allgemeinen wie folgt reduziert .The oxide catalysts are generally reduced as follows.
Die Tabletten (10 g) werden in einem Röhrenreaktor mit einem Reduktionsgas (98% N2, 2% H2) mit einer Heizrate von l°C/min von Raumtemperatur auf 240°C erhitzt. Der durchschnittliche Reduktionsgrad des Cu ist größer als 95%.The tablets (10 g) are heated in a tubular reactor with a reducing gas (98% N 2 , 2% H 2 ) at a heating rate of 1 ° C / min from room temperature to 240 ° C. The average degree of reduction of Cu is greater than 95%.
Gegenstand der Erfindung ist ferner ein Verfahren zur Herstellung des vorstehend angegebenen Katalysators, das dadurch gekennzeichnet ist, dass man aus einer Lösung von Cu- und Zn- Salzen und eines Teils der Al-Salze mit einer Alkalicarbonat- oder Alkalialuminatlösung die entsprechenden Hydroxocarbonate bzw. Hydroxide ausfällt, wobei entweder die Lösung der Cu- und Zn-Salze oder die Alkalicarbonat- oder Alkalialuminatlösung ein Aluminiumhydroxidsol enthält, worauf man den erhaltenen Niederschlag von der Fällungslösung abtrennt, wäscht, trocknet, calciniert und gegebenenfalls reduziert.The invention further relates to a process for the preparation of the catalyst indicated above, which is characterized in that the corresponding hydroxocarbonates or hydroxides are obtained from a solution of Cu and Zn salts and part of the Al salts with an alkali metal carbonate or alkali metal aluminate solution precipitates, with either the solution of the Cu and Zn salts or the alkali carbonate or alkali aluminate solution containing an aluminum hydroxide sol, whereupon the precipitate obtained is separated from the precipitation solution, washed, dried, calcined and optionally reduced.
Vorzugsweise verwendet man als Cu- und Zn-Salze die entsprechenden Nitrate und als Alkalicarbonate bzw. Alkalialuminate die entsprechenden Natriumverbindungen. Die nach der Fällung und Trocknung erhaltene Vorstufe des erfindungsgemäßen Katalysators hat einen geringeren Anteil an hydrotalcitanaloger Phase als der bekannte Katalysator, weil das Aluminiumhydroxidsol nicht mehr unter Hydrotalcitbildung reagiert. Unter einer hydrotalcitanalogen Phase versteht man einen Hydrotalcit, in welchem das Magnesium durch Kupfer und Zink ersetzt ist. Dementsprechend ist der Anteil der Malachitphase in der getrockneten Vorstufe höher als bei dem bekannten Katalysator. Die Malachitphase besteht im wesentlichen aus einem basischen Cu/Zn-Carbonat . Bei der thermischen Behandlung bildet sich daraus ein Cu/Zn-Mischoxid bzw. ein Gemisch aus CuO und ZnO in feiner Verteilung. Die hydrotal- citanaloge Phase bildet bei der thermischen Behandlung eine Cu/Al-Oxidphase, die nach der Reduktion einen Katalysator mit verhältnismäßig hoher Stabilität, aber geringerer Aktivität ergibt. Der aus der Malachitphase erhaltene Katalysator ist aktiv, aber nicht so stabil.The corresponding nitrates are preferably used as Cu and Zn salts and the corresponding sodium compounds as alkali metal carbonates or alkali metal aluminates. The precursor of the catalyst according to the invention obtained after the precipitation and drying has a lower proportion of hydrotalcite analog phase than the known catalyst, because the aluminum hydroxide sol no longer reacts with the formation of hydrotalcite. A hydrotalcite analog phase is a hydrotalcite in which the magnesium is replaced by copper and zinc. Accordingly, the proportion of the malachite phase in the dried precursor is higher than in the known catalyst. The malachite phase consists essentially of a basic Cu / Zn carbonate. During the thermal treatment, a Cu / Zn mixed oxide or a mixture of CuO and ZnO is formed in a fine distribution. During the thermal treatment, the hydrotalcite-analog phase forms a Cu / Al oxide phase which, after reduction, gives a catalyst with relatively high stability but less activity. The catalyst obtained from the malachite phase is active but not as stable.
Die hydrotalcitähnliche Phase und die Malachitphase können durch Röntgenbeugungsanalyse der getrockneten Vorstufe bestimmt werden. Nach der thermischen Behandlung verschwinden diese Phasen.The hydrotalcite-like phase and the malachite phase can be determined by X-ray diffraction analysis of the dried precursor. These phases disappear after the thermal treatment.
Die BET-Oberflache hängt ebenfalls von dem Cu/Zn-Atomverhältnis ab. Sie liegt im Allgemeinen zwischen etwa 90 und 120 m2/g und ist damit höher als die BET-Oberflache des bekannten Katalysators . Auch das Porenvolumen hängt von den Cu/Zn-Atomverhältnis ab. Es liegt im allgemeinen zwischen etwa 320 und 500 mm 3/g vorzugsweise zwischen etwa 320 bis 380 mm3/g und ist damit höher als bei dem bekannten Katalysator.The BET surface area also depends on the Cu / Zn atomic ratio. It is generally between about 90 and 120 m 2 / g and is therefore higher than the BET surface area of the known catalyst. The pore volume also depends on the Cu / Zn atomic ratio. It is generally between about 320 and 500 mm 3 / g, preferably between about 320 and 380 mm 3 / g, and is therefore higher than in the known catalyst.
Ferner ist Gegenstand der Erfindung die Verwendung des Katalysators für die MethanolSynthese. Die Versuche zur Methanolsynthese ergaben, dass bei abnehmendem Cu/Zn-Atomverhältnis die thermische Stabilität der Katalysatoren erhöht wird. Das Zinkoxid fungiert als Platzhalter, der ein schnelles Zusammensintern der Cu-Kristallite im reduzierten Katalysator verhindert. Die Größe der Kupferkristallite nimmt während der Methanolsynthese in Abhängigkeit vom C02-Partialdruck zu ab, d.h. die Cu-Kristallite wachsen stärker bei höheren C02-Partialdrucken.The invention also relates to the use of the catalyst for methanol synthesis. The experiments on methanol synthesis showed that the thermal stability of the catalysts is increased as the Cu / Zn atomic ratio decreases. The zinc oxide acts as a placeholder, which prevents the Cu crystallites from sintering together quickly in the reduced catalyst. The size of the copper crystallites decreases during the methanol synthesis depending on the CO 2 partial pressure, ie the Cu crystallites grow more strongly at higher CO 2 partial pressures.
Die Erfindung ist durch die nachstehenden Beispiele in nicht einschränkender Weise erläutert:The invention is illustrated in a non-limiting manner by the following examples:
Beispiel 1: Cu/Zn = 2,3Example 1: Cu / Zn = 2.3
A) Herstellung der Fällungslösungen: a) Herstellung der Sodalösung:A) Preparation of the precipitation solutions: a) Preparation of the soda solution:
Es wurde mit destilliertem Wasser (141 Liter) bei 50°C durch Zusatz von Na2C03 (25,15kg) eine 15.37 gew.-%ige Soda- lösung mit einem Lösungsvolumen von 143 Liter hergestellt. Die Lösung hatte eine Dichte von 1,154 g/ml bei 38°C.A 15.37% by weight sodium carbonate solution with a solution volume of 143 liters was prepared with distilled water (141 liters) at 50 ° C. by adding Na 2 CO 3 (25.15 kg). The solution had a density of 1.154 g / ml at 38 ° C.
b) Herstellung der Cu/Zn-Nitratlösung:b) Preparation of the Cu / Zn nitrate solution:
Cu(N03)2 x 3H20 (20,23kg) wurde in einem 50-Liter-Behälter mit destilliertem Wasser (24,2kg) von 50°C versetzt. Dann wurde in einem 30-Liter-Behälter ZnO-Pulver (4,43kg, dis- pergiert in 6.3kg H20) mit 86%-iger HN03-Lösung (10,08kg) vollständig aufgelöst. Die Cu- und Zn-Lösungen wurden in einem 300-Liter-Behälter miteinander vermischt. Es wurde eine klare Lösung ohne Niederschlag erhalten.Cu (N0 3 ) 2 x 3H 2 0 (20.23kg) was mixed with distilled water (24.2kg) at 50 ° C in a 50 liter container. Then, in a 30 liter container, ZnO powder (4.43 kg, dispersed in 6.3 kg H 2 O) with 86% HN0 3 solution (10.08 kg) was completely dissolved. The Cu and Zn solutions were mixed together in a 300 liter container. A clear solution with no precipitate was obtained.
c) Herstellung der Al/Na-Nitratlösung:c) Preparation of the Al / Na nitrate solution:
In einen 30-Liter-Behälter wurde NaAl02 (1,63kg) in destilliertes Wasser (7,5kg) bei 22°C gegeben. Dann wurde 68%-ige HN03 (6,4kg) zugesetzt. Während der ersten 1 bis 2 min. nach Zugabe der HN03 wurde eine Gelierung und eine Viskositätszunahme beobachtet. Weiterhin stieg die Temperatur auf 97° bis 98 °C. Nach Zugabe der HN03 war die Lösung etwas bräunlich gefärbt, enthielt aber keinen Niederschlag. Dann wurde die Al/Na-Nitratlösung in die Cu/Zn-Nitratlösung gepumpt.In a 30 liter container NaAl0 2 (1.63 kg) was placed in distilled water (7.5 kg) at 22 ° C. Then became 68% HN0 3 (6.4kg) added. During the first 1 to 2 min. after the addition of HN0 3 , gelling and an increase in viscosity were observed. Furthermore, the temperature rose to 97 ° to 98 ° C. After adding the HN0 3 , the solution was a little brownish in color, but contained no precipitate. Then the Al / Na nitrate solution was pumped into the Cu / Zn nitrate solution.
d) Herstellung des Aluminiumhydroxid-Sols : Natriumaluminat (1,63kg) und destilliertes Wasser (7,5kg) wurden in einem 15-Liter-Behälter 30 min. gerührt, wobei sich ein Aluminiumhydroxid-Sol bildete. Das erhaltene Sol (8,46 Liter) wurde in die Cu/Zn/Al-Nitratlösung gepumpt. Es bildete sich ein weißer Niederschlag, der sich aber langsam wieder auflöste.d) Preparation of the aluminum hydroxide sol: Sodium aluminate (1.63 kg) and distilled water (7.5 kg) were in a 15 liter container for 30 minutes. stirred, forming an aluminum hydroxide sol. The resulting sol (8.46 liters) was pumped into the Cu / Zn / Al nitrate solution. A white precipitate formed, which slowly dissolved again.
Zur Vervollständigung der Cu/Zn/Al-Lösung wurde destilliertes Wasser bei zu einem Gesamtvolumen von 84,6 Liter hinzugegeben und die Lösung wurde auf 74°C erhitzt. Die Dichte der Lösung betrug 1,350 bis 1,352 g/ml .To complete the Cu / Zn / Al solution, distilled water was added to a total volume of 84.6 liters and the solution was heated to 74 ° C. The density of the solution was 1.350 to 1.352 g / ml.
B) Fällung:B) Precipitation:
Die Nitratlösung (enthaltend Aluminiumhydroxid-Sol) und die Sodalδsung wurden bei einer Temperatur von 74 °C gleichzeitig durch das Mischrohr in den Fällbehälter gepumpt . Die Temperatur im Fällbehälter betrug 60°C, der pH-Wert etwa 6,5. Die Verweilzeit im Fällbehälter betrug etwa 5 bis 10 min.. Die Suspension wird kontinuierlich vom Fällungsbehälter in den Alterungsbehälter gepumpt.The nitrate solution (containing aluminum hydroxide sol) and the soda solution were simultaneously pumped through the mixing tube into the precipitation tank at a temperature of 74 ° C. The temperature in the precipitation tank was 60 ° C, the pH about 6.5. The residence time in the precipitation container was about 5 to 10 minutes. The suspension is pumped continuously from the precipitation container into the aging container.
C) Alterung:C) Aging:
Nach Beendigung der Fällung wurde die Suspension auf 70 °C erwärmt. Der Niederschlag wurde 60 min. bei 70°C gealtert- Die Farbe des Niederschlages ändert sich von hellblau (Beginn der Alterung) zu grün (Ende der Alterung) . Der pH-Wert stieg im Laufe der Alterung von 6,6 + 0,1 auf 7,3 ± 0,1.After the precipitation had ended, the suspension was heated to 70.degree. The precipitation was 60 min. aged at 70 ° C The color of the precipitation changes from light blue (start of aging) to green (end of aging). The pH rose from 6.6 + 0.1 to 7.3 ± 0.1 in the course of aging.
D) Waschen, Filtration:D) washing, filtration:
Die Suspension wurde nach der Alterung filtriert . Der feuchte Filterkuchen wurde in destilliertem Wasser aufgeschlämmt und erneut filtriert. Dieser Vorgang wurde wiederholt, bis der Na-Gehalt im Filterkuchen < 350 ppm betrug.The suspension was filtered after aging. The wet filter cake was slurried in distilled water and filtered again. This process was repeated until the Na content in the filter cake was <350 ppm.
E) Trocknung:E) Drying:
Der Filterkuchen wurde durch Zugabe von Wasser bis auf eine Oxidkonzentration von 10% aufgeschlämmt und im Sprühtrockner bei einer Eintrittstemperatur von 275 bis 280 °C und einer Austrittstemperatur von 105 bis 115°C getrocknet.The filter cake was slurried to an oxide concentration of 10% by adding water and dried in a spray dryer at an inlet temperature of 275 to 280 ° C and an outlet temperature of 105 to 115 ° C.
F) Thermische Behandlung:F) Thermal treatment:
Der gewaschene Katalysatorvorläufer wurde anschließend 3 Std. bei 320°C calciniert.The washed catalyst precursor was then calcined at 320 ° C. for 3 hours.
G) Reduktion:G) Reduction:
Der oxidische Katalysatorvorläufer wurde in einem Röhrenreaktor mit einem Reduktionsgas (98% N2; 2% H2) mit einer Heizrate von l°C/min. von Raumtemperatur auf 240°C erhitzt. Der durchschnittliche Reduktionsgrad des Cu war 85%. Die Größe der Cu- Kristallite nach der Reduktion betrug 6,3nm. Beispiel 2: Cu/Zn = 2,4The oxidic catalyst precursor was in a tubular reactor with a reducing gas (98% N 2 ; 2% H 2 ) at a heating rate of 1 ° C / min. heated from room temperature to 240 ° C. The average degree of reduction of the Cu was 85%. The size of the Cu crystallites after the reduction was 6.3 nm. Example 2: Cu / Zn = 2.4
Die Arbeitsweise von Beispiel 1 wurde mit der Abweichung wiederholt, dass das eingesetzte Cu/Zn-Verhältnis 2,4 und der pH während der Fällung 7,0 + 0,1 betrug. Die Größe der Cu- Kristallite nach der Reduktion betrug 6,8 nm.The procedure of Example 1 was repeated with the difference that the Cu / Zn ratio used was 2.4 and the pH during the precipitation was 7.0 + 0.1. The size of the Cu crystallites after the reduction was 6.8 nm.
Beispiel 3: Cu/Zn = 2,62Example 3: Cu / Zn = 2.62
Die Arbeitsweise von Beispiel 2 wurde mit der Abweichung wiederholt, dass das eingesetzte Cu/Zn-Verhältnis 2,62 betrug. Die Größe der Cu-Kristallite nach der Reduktion betrug 7,5 nm.The procedure of Example 2 was repeated with the difference that the Cu / Zn ratio used was 2.62. The size of the Cu crystallites after the reduction was 7.5 nm.
Beispiel 4: Cu/Zn = 2,8Example 4: Cu / Zn = 2.8
Herstellung des Katalysators nach EP-A-125 689 (Vergleichsbeispiel) .Preparation of the catalyst according to EP-A-125 689 (comparative example).
Zur Fällung des Katalysatorvorläufers werden 2 Lösungen hergestellt :Two solutions are prepared to precipitate the catalyst precursor:
Lösung 1 : 418g Kupfernitrat und 50g ZnO werden in 1 Liter Wasser und 148g 52,5 %iger HN03 gelöst und anschließend mit einer Lösung von 93,8g A1(N03)3 x 9H20 in 0,5 Liter Wasser versetzt .Solution 1: 418 g of copper nitrate and 50 g of ZnO are dissolved in 1 liter of water and 148 g of 52.5% HN0 3 and then a solution of 93.8 g of A1 (N0 3 ) 3 x 9H 2 0 in 0.5 liters of water is added.
Lösung 2 : 410g Natriumcarbonat wurden in 2 Liter Wasser gelöst.Solution 2: 410 g of sodium carbonate were dissolved in 2 liters of water.
Die Lösungen wurden getrennt auf 68°C erwärmt und unter starkem Rühren in der Weise vereinigt, dass der pH-Wert während der Fällung 6,7 betrug. Der Niederschlag wurde unter Rühren bei 68°C noch eine Stunde in der Mutterlauge gealtert. An- schließend wurde abfiltriert und mit Wasser natriumfrei gewaschen. Der Filterkuchen wurde bei 120°C getrocknet und anschließend 8 Stunden bei 280°C calciniert. Das calcinierte Produkt wurde zerkleinert und anschließend nach Zugabe von 2 Gew.-% Graphit verpresst .The solutions were heated separately to 68 ° C. and combined with vigorous stirring in such a way that the pH was 6.7 during the precipitation. The precipitate was aged with stirring at 68 ° C. for one hour in the mother liquor. On- it was finally filtered off and washed free of sodium with water. The filter cake was dried at 120 ° C and then calcined at 280 ° C for 8 hours. The calcined product was crushed and then compressed after adding 2% by weight of graphite.
Die Größe der Cu-Kristallite nach der Reduktion betrug 8,5 nm.The size of the Cu crystallites after the reduction was 8.5 nm.
Die chemische Zusammensetzung und die physikalischen Eigenschaften der Katalysatoren nach den vorstehenden Beispielen sind in Tabelle I angegeben. The chemical composition and the physical properties of the catalysts according to the examples above are given in Table I.
Tabelle I Chemische und physikalische EigenschaftenTable I Chemical and physical properties
Beispiel 1 Beispiel 2 Beispiel 3 Beispiel 4Example 1 Example 2 Example 3 Example 4
Zusammensetzung*Composition*
CuO [%] 63 63 64 65CuO [%] 63 63 64 65
ZnO [%] 27 26 25 24ZnO [%] 27 26 25 24
A1203 [%] 10 11 11 11A1 2 0 3 [%] 10 11 11 11
Cu/Zn [mol/mol] 2,3 2,4 2,62 2,8Cu / Zn [mol / mol] 2.3 2.4 2.62 2.8
Physikalischephysical
Eigenschaftencharacteristics
Tablettengröße [mm] 6-3,5 6-3,5 6-3,5 6-3,5Tablet size [mm] 6-3.5 6-3.5 6-3.5 6-3.5
Schüttgewicht [g/1] 1040 1010 1050 1050Bulk weight [g / 1] 1040 1010 1050 1050
Seitedruckfestigkeit [N] 155 155 160Side pressure resistance [N] 155 155 160
BET-OF [m/g] ** 98 95 90 80BET OF [m / g] ** 98 95 90 80
Porenvolumenpore volume
[mm3/g] *** 330 330 320 280[mm 3 / g] *** 330 330 320 280
Porengrößenvertei- lung [%] ***Pore size distribution [%] ***
> 1750 nm 0 0 0 0> 1750 nm 0 0 0 0
80 - 1750 nm 1,6 2,6 4,0 5,380 - 1750 nm 1.6 2.6 4.0 5.3
14 - 80 nm 65,3 66,1 60,9 71,414-80 nm 65.3 66.1 60.9 71.4
7,5 - 14 nm 33,1 31,3 35,1 23,37.5 - 14 nm 33.1 31.3 35.1 23.3
* Glühverlust bestimmt bei 600°C* Loss on ignition determined at 600 ° C
** Die BET-Oberflache wurde nach der N2- Einpunktmethode bei 77 K in Anlehnung an DIN 66132 bestimmt.** The BET surface area was determined using the N 2 single-point method at 77 K in accordance with DIN 66132.
*** Das Porenvolumen wurde nach der Qecksilber-Instrusionsme- thode in Anlehnung an DIN 66133 bestimmt Die Aktivitäten bei der MethanolSynthese wurden unter den in Tabelle II angegebenen Bedingungen getestet. Der Anteil der Nebenprodukte stellt ein Maß für die Selektivität dar. Die Ergebnisse sind ebenfalls in Tabelle II angegeben. *** The pore volume was determined using the mercury intrusion method based on DIN 66133 The activities in methanol synthesis were tested under the conditions given in Table II. The proportion of by-products is a measure of the selectivity. The results are also shown in Table II.
Tabelle IITable II
Ergebnisse des Methanolsynthese -TestsResults of the methanol synthesis test
Bsp. 1 Bsp. 2 Bsp. 3 Bsp. 1 Bsp. 2 Bsp. 3Ex. 1 Ex. 2 Ex. 3 Ex. 1 Ex. 2 Ex. 3
Testbedingungentest conditions
Katalysatorvolumen [ml] 15 15Catalyst volume [ml] 15 15
Testdauer [h] 245 96Test duration [h] 245 96
Temperatur [°C] 250 230 210 250 235Temperature [° C] 250 230 210 250 235
Druck [bar g] 60 45Pressure [bar g] 60 45
Gaszusammensetzung [%]Gas composition [%]
N2 6,88 2,8N 2 6.88 2.8
CO 5,93 10,8CO 5.93 10.8
CH4 19,34 7,2CH 4 19.34 7.2
C02 8, 05 3,9C0 2 8, 05 3.9
H2 59,79 75,3H 2 59.79 75.3
Gasstrom [Nl/h] 330 300Gas flow [Nl / h] 330 300
Testergebnissetest results
GZA [kg/kg h]GZA [kg / kg h]
T = 250°C 1,127 1,084 1,053T = 250 ° C 1.127 1.084 1.053
T = 230°C 0,946 0,75 0,739T = 230 ° C 0.946 0.75 0.739
T = 210°C 0,4 0,305 0,297T = 210 ° C 0.4 0.305 0.297
T = 250°C 1,144 1,064 1,039T = 250 ° C 1.144 1.064 1.039
T = 235°C 1,28 1,206 0,959T = 235 ° C 1.28 1.206 0.959
Nebenprodukte [ppm]By-products [ppm]
Gesamttotal
T = 250°C 926 957 1067T = 250 ° C 926 957 1067
T = 230°C 568 542 656T = 230 ° C 568 542 656
T = 210°C 278 294 336T = 210 ° C 278 294 336
T = 250°C 869 967 1015T = 250 ° C 869 967 1015
T = 235°C 713 838 1034T = 235 ° C 713 838 1034
Ethanolethanol
T = 250°C 162 182 245T = 250 ° C 162 182 245
T = 230°C 35 45 65T = 230 ° C 35 45 65
T = 210°C 2 3 5T = 210 ° C 2 3 5
T = 250°C 157 192 243 Aus Tabelle II ergibt sich ferner, dass mit abnehmendem Cu/Zn-Verhältnis die katalytische Aktivität steigt. Die Langzeitaktivität der erfindungsgemäßen Katalysatoren ist besser als die des Vergleichskatalysators.T = 250 ° C 157 192 243 Table II also shows that the catalytic activity increases as the Cu / Zn ratio decreases. The long-term activity of the catalysts according to the invention is better than that of the comparative catalyst.
Ferner wurden zur Bestimmung der Selektivität die Nebenprodukte sowie der Ethanolgehalt als Funktion der Betriebsdauer bestimmt. Bei den Nebenprodukten handelt es sich um höhere Kohlenwasserstoffe (C3 bis Cχ0) , Alkohole (C2 bis C5) , Ether, Ester und Ketone. Diese werden gaschromatographisch bestimmt. Die Nebenprodukte stören auch im ppm-Bereich, wenn sie im Methanol vorhanden sind. Die Nebenprodukte im Methanol erfordern eine teure Aufarbeitung (Destillation) des Methanols.The by-products and the ethanol content were also determined as a function of the operating time in order to determine the selectivity. The by-products are higher hydrocarbons (C 3 to Cχ 0 ), alcohols (C 2 to C 5 ), ethers, esters and ketones. These are determined by gas chromatography. The by-products also interfere in the ppm range if they are present in the methanol. The by-products in the methanol require expensive processing (distillation) of the methanol.
Die Ergebnisse sind ebenfalls in Tabelle II angegeben.The results are also shown in Table II.
Ferner wurden die Cu-Kristallitgrößen der Katalysatoren nach den Beispielen 1 bis 4 vor und nach der Methanolsynthese bestimmt. Die Ergebnisse sind in Tabelle III zusammengefasst .Furthermore, the Cu crystallite sizes of the catalysts according to Examples 1 to 4 were determined before and after the methanol synthesis. The results are summarized in Table III.
Mit abnehmendem Cu/Zn-Atomverhältnis wird ein geringeres Anwachsen der Cu-Kristallite beobachtet.With a decreasing Cu / Zn atomic ratio, less growth of the Cu crystallites is observed.
Tabelle III Cu-Kristallitgrößen vor und nach der MethanolSyntheseTable III Cu crystallite sizes before and after methanol synthesis
Cu/Zn Cu-Kristallitgröpße [nm]Cu / Zn Cu crystallite size [nm]
Katalysator A omverhältnis vor Test nach TestCatalyst ratio before test after test
Beispiel 1 2,3 6,3 7,5Example 1 2.3 6.3 7.5
Beispiel 2 2,4 6,8 8,5Example 2 2.4 6.8 8.5
Besipiel 3 2,62 7,5 10,5Example 3 2.62 7.5 10.5
Beispiel 4 2,8 8,5 12 Example 4 2.8 8.5 12

Claims

Patentansprüche claims
1. Cu/Zn/Al-Katalysator, enthaltend Kupferoxid und Zinkoxid als katalytisch wirksame Substanzen und Aluminiumoxid als thermostabilisierende Substanz, dadurch gekennzeichnet, dass das Cu/Zn-Atomverhältnis < 2,8 ist und dass die Aluminiumoxid-Komponente mindestens teilweise aus einem Aluminiumhy- droxid-Sol erhalten worden ist.1. Cu / Zn / Al catalyst containing copper oxide and zinc oxide as catalytically active substances and aluminum oxide as a thermostabilizing substance, characterized in that the Cu / Zn atomic ratio is <2.8 and that the aluminum oxide component is at least partially made of an aluminum hy - hydroxide sol has been obtained.
2. Katalysator nach Anspruch 1, dadurch gekennzeichnet, dass das Cu/Zn-Atomverhältnis zwischen etwa 1,8 und 2,7 liegt .2. Catalyst according to claim 1, characterized in that the Cu / Zn atomic ratio is between about 1.8 and 2.7.
3. Katalysator nach Anspruch 1 oder 2, in Form von Tabletten, Ringen oder Waben.3. Catalyst according to claim 1 or 2, in the form of tablets, rings or honeycombs.
4. Katalysator nach einem der vorhergehenden Ansprüche, dadurch gekennzeichnet, dass er vor dem Einsatz zumindest teilweise reduziert ist.4. Catalyst according to one of the preceding claims, characterized in that it is at least partially reduced before use.
5. Katalysator nach einem der vorhergehenden Ansprüche, dadurch gekennzeichnet, dass die Größe der Kupferkristallite im reduzierten Zustand etwa 6 bis 7 nm beträgt.5. Catalyst according to one of the preceding claims, characterized in that the size of the copper crystallites in the reduced state is about 6 to 7 nm.
6. Katalysator nach einem der vorhergehenden Ansprüche, dadurch gekennzeichnet, der Anteil der Aluminiumoxidkomponente etwa 1 bis 20, vorzugsweise etwa 5 bis 20 Gew.-% beträgt.6. Catalyst according to one of the preceding claims, characterized in that the proportion of the aluminum oxide component is about 1 to 20, preferably about 5 to 20 wt .-%.
7. Katalysator nach einem der Ansprüche 1 bis 6, dadurch gekennzeichnet, dass er im oxidischen Zustand eine BET- Oberflache von etwa 90 bis 120 ml/g und ein Porenvolumen von etwa 320 bis 500 m2/g, vorzugsweise etwa 320 bis 380 ml/g hat. 7. Catalyst according to one of claims 1 to 6, characterized in that in the oxidic state it has a BET surface area of approximately 90 to 120 ml / g and a pore volume of approximately 320 to 500 m 2 / g, preferably approximately 320 to 380 ml / g has.
8. Verfahren zur Herstellung des Katalysators nach einem der Ansprüche 1 bis 7, dadurch gekennzeichnet, dass man aus einer Lösung von Cu- und Zn-Salzen und eines Teils der Al- Salze mit einer Alkalicarbonat- oder Alkalialuminatlösung die entsprechenden Hydroxocarbonate bzw. Hydroxide ausfällt, wobei entweder die Lösung der Cu- und Zn-Salze oder die Alkalicarbonat- oder Alkalialuminatlösung ein Aluminiumhydroxidsol enthält, worauf man den erhaltenen Niederschlag von der Fällungslösung abtrennt, wäscht, trocknet, calciniert und gegebenenfalls reduziert.8. A process for the preparation of the catalyst according to one of claims 1 to 7, characterized in that the corresponding hydroxocarbonates or hydroxides precipitate from a solution of Cu and Zn salts and part of the Al salts with an alkali metal carbonate or alkali metal aluminate solution , wherein either the solution of the Cu and Zn salts or the alkali carbonate or alkali aluminate solution contains an aluminum hydroxide sol, whereupon the precipitate obtained is separated from the precipitation solution, washed, dried, calcined and optionally reduced.
9. Verfahren nach Anspruch 8, dadurch gekennzeichnet, dass man als Cu- und Zn-Salze die entsprechenden Nitrate und als Alkalicarbonate bzw. Alkalialuminate die entsprechenden Natriumverbindungen verwende .9. The method according to claim 8, characterized in that the corresponding nitrates are used as Cu and Zn salts and the corresponding sodium compounds are used as alkali metal carbonates or alkali metal aluminates.
10. Verwendung des Katalysators nach einem der Ansprüche 1 bis 7 oder hergestellt nach Anspruch 8 oder 9 für die Methanolsynthese . 10. Use of the catalyst according to one of claims 1 to 7 or prepared according to claim 8 or 9 for the methanol synthesis.
EP02805277A 2001-12-08 2002-11-06 Cu/zn/al catalyst for methanol synthesis Withdrawn EP1450946A1 (en)

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DE10160486 2001-12-08
DE10160486A DE10160486A1 (en) 2001-12-08 2001-12-08 Copper-zinc-aluminium catalyst for use in methanol synthesis has a relatively low copper to zinc atom ratio and contains the aluminum oxide component in the form of an aluminum hydroxide sol
PCT/EP2002/012395 WO2003053569A1 (en) 2001-12-08 2002-11-06 Cu/zn/al catalyst for methanol synthesis

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JP2005537119A (en) 2005-12-08
US20050080148A1 (en) 2005-04-14
AU2002357496A1 (en) 2003-07-09
WO2003053569A1 (en) 2003-07-03
ZA200404331B (en) 2005-08-31
CA2469531C (en) 2011-05-17
NO329151B1 (en) 2010-08-30
US7754651B2 (en) 2010-07-13
NO20042614L (en) 2004-06-22

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