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US-12623211-B2 - Method for making copper-containing catalysts

US12623211B2US 12623211 B2US12623211 B2US 12623211B2US-12623211-B2

Abstract

A method for preparing a copper-containing catalyst is described comprising the steps of: (a) combining an acidic copper-containing solution with a basic precipitant solution in a first precipitation step to form a first precipitate, (b) combining an alkali metal aluminate solution with an acidic solution in a second precipitation step to form a second precipitate, (c) contacting the first and second precipitates together in a further precipitate mixing step to form a catalyst precursor, and (d) washing, drying and calcining the catalyst precursor to form the copper-containing catalyst, wherein at least 70% by weight of the copper in the catalyst is present in the first precipitate and a silica precursor is included in the first precipitation step, the second precipitation step or the precipitate mixing step, to provide a catalyst with a silica content, expressed as SiO 2 , in the range of 0.1 to 5.0 wt %.

Inventors

  • Youxin CUI
  • Monica GARCIA
  • Pauline Elizabeth GLEN
  • Norman MacLeod
  • Michael Thomas NICHOLSON
  • Simone ROLOFF-STANDRING
  • Kaamila UN DIN

Assignees

  • JOHNSON MATTHEY DAVY TECHNOLOGIES LIMITED

Dates

Publication Date
20260512
Application Date
20210906
Priority Date
20201002

Claims (20)

  1. 1 . A method for preparing a copper-containing catalyst comprising the steps of: (a) combining an acidic copper-containing solution with a basic precipitant solution in a first precipitation step to form a first precipitate, (b) combining an alkali metal aluminate solution with an acidic solution in a second precipitation step to form a second precipitate, (c) contacting the first and second precipitates together in a further precipitate mixing step to form a catalyst precursor, and (d) washing, drying and calcining the catalyst precursor to form the copper-containing catalyst, wherein at least 70% by weight of the copper in the catalyst is present in the first precipitate and a silica precursor is included in the first precipitation step, the second precipitation step or the precipitate mixing step, to provide a catalyst with a silica content, expressed as SiO 2 , in a range of 0.1 to 5.0 wt %.
  2. 2 . The method according to claim 1 , wherein the first precipitation step is performed by combining an aqueous acidic copper-containing solution containing copper and zinc compounds with an aqueous alkali metal carbonate solution in a first precipitation vessel.
  3. 3 . The method according to claim 2 , wherein the copper and zinc compounds are nitrates and the aqueous alkali metal carbonate solution comprises sodium carbonate or potassium carbonate.
  4. 4 . The method according to claim 1 , wherein at least 80% by weight of the copper in the catalyst is present in the first precipitate.
  5. 5 . The method according to claim 2 , wherein zinc compounds are included in both the first precipitation step and the second precipitation step and the amount of zinc in the second precipitation step is in a range of 0.5 to 50% of the total zinc added.
  6. 6 . The method according to claim 1 , wherein one or more promoter compounds selected from compounds of Mg, Co, Mn, V, Ti, Zr or rare earths are included in the acidic copper-containing solution in the first precipitation step and/or the acidic solution in the second precipitation step.
  7. 7 . The method according to claim 1 , wherein the first precipitation step is performed at a temperature in a range of 40 to 80° C.
  8. 8 . The method according to claim 1 , wherein the acidic copper-containing solution and the basic precipitant solution are added simultaneously to the first precipitation vessel such that the pH in the first precipitation vessel is maintained between 6 and 9.
  9. 9 . The method according to claim 1 , wherein the second precipitation step is performed by combining an aqueous solution containing sodium aluminate or potassium aluminate with an aqueous nitric acid solution, optionally containing one or more copper compounds, one or more zinc compounds and/or one or more promoter metal compounds, in a second precipitation vessel.
  10. 10 . The method according to claim 1 , wherein the second precipitation step is performed at a temperature in a range of 10 to 80° C.
  11. 11 . The method according to claim 1 , wherein the acidic solution and the alkali metal aluminate solution are combined in a second precipitation vessel with a final precipitation pH between 3 and 9.
  12. 12 . The method according to claim 1 , wherein the second precipitate formed in step (b) and/or the first and second precipitates contacted in step (c) are aged at a temperature in a range of 10 to 80° C.
  13. 13 . The method according to claim 1 , wherein step (a) and step (b) are performed simultaneously.
  14. 14 . The method according to claim 1 , wherein neither of the precipitates from steps (a) and (b) are separated and washed prior to the precipitate mixing step (c).
  15. 15 . The method according to claim 1 , wherein in step (c) slurries of the first and second precipitates are combined in a mixing vessel.
  16. 16 . The method according to claim 1 , wherein step (c) is performed at the same time as step (a) or step (b).
  17. 17 . The method according to claim 1 , wherein the catalyst has a silica content, expressed as SiO 2 , in a range of 0.1 to 3.0 wt %.
  18. 18 . The method according to claim 1 , wherein the silica precursor is a colloidal silica or silica sol, a water-soluble silicon compound, an alkali metal silicate, or an organo-silicate.
  19. 19 . The method according to claim 1 , wherein an acidic silica sol is included in the acidic copper-containing solution in the first precipitation step, the acidic solution in the second precipitation step, the first precipitate, the second precipitate or a mixture of the first and second precipitates in the precipitate mixing step.
  20. 20 . The method according to claim 1 , wherein an alkali metal silicate or basic silica sol is included in the basic precipitant solution in the first precipitation step, the alkali metal aluminate solution in the second precipitation step, the first precipitate, the second precipitate or a mixture of the first and second precipitates in the precipitate mixing step.

Description

This invention relates to methods of manufacture of copper-containing catalysts, in particular copper-containing catalysts suitable for the water-gas shift reaction and methanol synthesis. The copper-containing catalysts for such reactions are generally produced by forming into pellets small discrete particles of an intimate mixture of copper oxide and one or more oxidic materials, generally including zinc oxide, that are not substantially reduced under the conversion reaction process conditions. The intimate mixture is generally made by precipitation of copper compounds and compounds convertible to the other oxidic materials, and/or precipitation of the copper compounds in the presence of the other oxidic materials or compounds convertible thereto, followed by calcination to convert the precipitated copper compounds, and other components as necessary, to the oxides. In some cases, the copper-containing catalyst has been modified with silica. U.S. Pat. Nos. 6,048,820 and 9,314,774 disclose silica-modified methanol synthesis catalysts produced using a single precipitation step employing aluminium nitrate. We have found that materials prepared using this method have relatively low activities. CN101306369 discloses a catalyst preparation method comprising: (1), an acidic solution of Al is precipitated by reaction with a sodium carbonate solution which also contains sodium silicate; (2) Cu and Zn compounds are co-precipitated by reaction with an alkali metal carbonate; and (3) the two obtained co-precipitates are mixed, aged, then filtered, washed, dried and calcined. We have found catalysts prepared by this route using acidic aluminium solutions have relatively low initial activity and poor stability. This may be due in part to a high level of retained alkali in materials prepared via this method. CN110935478 discloses a catalyst preparation method comprising: (1) carrying out a parallel flow gelling reaction on a mixed solution A and a sodium meta-aluminate solution to obtain a first slurry; (2) adding a mixed solution B and a sodium carbonate solution into the first slurry in a dropwise and parallel flow manner, carrying out a gelling reaction to obtain a second slurry; and (3) carrying out solid-liquid separation on the material obtained in the step (2), and drying, calcining and pelleting the solid phase to obtain the catalyst, wherein the mixed solution A is an aqueous solution containing a soluble copper salt, a soluble zinc salt and a compound containing an element A, the mixed solution B is an aqueous solution containing a soluble copper salt, a soluble aluminium salt and a compound containing an element A, and the element A is one or a plurality of materials selected from boron, phosphorus and silicon. We have found that precipitating the majority of the copper and zinc against alkali metal aluminate in this way produces catalysts with relatively low activities. We have found an alternative, simpler, preparation method that provides improved catalyst performance. Accordingly the invention provides a method for preparing a copper-containing catalyst comprising the steps of: (a) combining an acidic copper-containing solution with a basic precipitant solution in a first precipitation step to form a first precipitate, (b) combining an alkali metal aluminate solution with an acidic solution in a second precipitation step to form a second precipitate, (c) contacting the first and second precipitates together in a further precipitate mixing step to form a catalyst precursor, and (d) washing, drying and calcining the catalyst precursor to form the copper-containing catalyst, wherein at least 70% by weight of the copper in the catalyst is present in the first precipitate and a silica precursor is included in the first precipitation step, the second precipitation step or the precipitate mixing step, to provide a catalyst with a silica content, expressed as SiO2, in the range of 0.1 to 5.0 wt %. The invention further includes a catalyst obtainable by the method and a process selected from methanol synthesis, methanol steam reforming and water-gas shift using the catalyst. Key aspects of the present method are the formation of a copper hydroxycarbonate phase and a separately precipitated alumina-containing support phase using a basic alumina source, to produce well dispersed and well supported copper crystallites, combined with the addition of a relatively low level of silica, which has a stabilising effect on the active catalyst components. Unlike CN110935478, the present method requires the majority of the copper to be precipitated against the basic precipitant and included separately from the aluminium source. In this way smaller copper crystallites with higher surface area and having a higher initial activity are produced. The present method provides catalysts having both high initial activity and excellent stability. The method includes (a) combining an acidic copper-containing solution with a basic precipit