Classifications

• • 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)
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• 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)

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• 2001
  • 2001-12-08 DE DE10160486A patent/DE10160486A1/de not_active Ceased
• 2002
  • 2002-11-06 US US10/497,865 patent/US7754651B2/en not_active Expired - Fee Related
  • 2002-11-06 WO PCT/EP2002/012395 patent/WO2003053569A1/de active Application Filing
  • 2002-11-06 CA CA2469531A patent/CA2469531C/en not_active Expired - Fee Related
  • 2002-11-06 AU AU2002357496A patent/AU2002357496A1/en not_active Abandoned
  • 2002-11-06 JP JP2003554322A patent/JP4343697B2/ja not_active Expired - Fee Related
  • 2002-11-06 EP EP02805277A patent/EP1450946A1/de not_active Withdrawn
• 2004
  • 2004-06-02 ZA ZA2004/04331A patent/ZA200404331B/en unknown
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