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EP-4739807-A1 - SYSTEM FOR RECOVERING VOLATILE PT AND/OR RH AND METHOD THEREOF

EP4739807A1EP 4739807 A1EP4739807 A1EP 4739807A1EP-4739807-A1

Abstract

The present disclosure discloses a catalytic system comprising a Pt-containing and/or Rh- containing catalyst, and a recovery system downstream of the catalyst, wherein the recovery system comprises one or more oxide of a rare earth metal selected from the group consisting of Er 2 O 3 , Sm 2 O 3 and Yb 2 O 3 . The present disclosure further relates to the use of one or more oxides of a rare earth metal selected from the group consisting of Er 2 O 3 , Sm2O3, and Yb 2 O 3 for recovering volatile Pt and/or Rh, and to a method for recovering volatile Pt and/or Rh.

Inventors

  • WALLER, DAVID

Assignees

  • Yara International ASA

Dates

Publication Date
20260513
Application Date
20240705

Claims (16)

  1. 1. A catalytic system comprising: • a Pt-containing and/or Rh-containing catalyst; and • a recovery system downstream of the catalyst; wherein the recovery system comprises one or more oxide of a rare earth metal selected from the group consisting of Er 2 C>3, So a and Yb2C>3.
  2. 2. The system according to claim 1 , wherein the catalytic system is a system for the catalytic conversion of ammonia into nitric oxide, for the generation of nitric acid, or wherein the catalytic system is a system for the catalytic conversion of ammonia, oxygen and methane, for the generation of hydrogen cyanide.
  3. 3. The system according to any one of claims 1 to 2, wherein the recovery system comprises Sm 2 O 3 .
  4. 4. The system according to claim 3, wherein the catalytic system comprises a Rh-containing catalyst.
  5. 5. The system according to any one of claims 1 to 4, wherein the Pt-containing and/or Rh- containing catalyst is in the form of catalytic gauze, and wherein the recovery system has the shape of a honeycomb, a tablet, a pellet, a sponge, a net or a gauze.
  6. 6. Use of one or more oxides of a rare earth metal selected from the group consisting of Er 2 O 3 , Sm 2 C>3 and Yb 2 C>3 for recovering volatile Pt and/or Rh.
  7. 7. The use according to claim 6, wherein volatile Pt and/or Rh is generated from the catalytic oxidation of ammonia into nitric oxide, or wherein volatile Pt and/or Rh is generated from the catalytic reaction of ammonia with oxygen and methane, thereby generating hydrogen cyanide.
  8. 8. The use according to claim 7, wherein the oxide of the rare earth metal is Sm 2 C>3.
  9. 9. The use according to claim 8, wherein volatile Rh is recovered.
  10. 10. The use according to any one of claims 7 to 8, wherein the oxide of a rare earth metal is comprised in a recovery system that has the shape of a honeycomb, a tablet, a pellet, a sponge, a net or a gauze.
  11. 11. A method for oxidising ammonia into nitric oxide or for reacting ammonia with oxygen and methane, thereby generating hydrogen cyanide comprising the steps of: a) catalytically oxidising ammonia into nitric oxide or catalytically reacting ammonia with oxygen and methane thereby generating hydrogen cyanide, whereby volatile Pt and/or Rh is generated; b) contacting the volatile Pt and/or Rh generated in step a) with a recovery system comprising one or more oxide of a rare earth metal selected from the group consisting of Er2C>3, So a, and Yb 2 C>3 to form a compound or a solid solution with Pt and/or Rh; and c) recovering Pt and/or Rh from the compound or the solid solution generated in step b).
  12. 12. The method according to claim 11 , wherein step a) is performed with a catalytic gauze, and wherein step b) is performed with a recovery system that has the shape of a honeycomb, a tablet, a pellet, a sponge, a net or a gauze.
  13. 13. The method according to any one of claims 11 to 12, wherein in step b) the oxide of the rare earth metal is Sm 2 O3.
  14. 14. The method according to claim 13, wherein step a) is performed with a Rh-containing catalytic system.
  15. 15. The method according to any one of claims 11 to 14, wherein step a) comprises catalytically oxidising ammonia into nitric oxide in the production of nitric acid at a temperature ranging from 700 to 950 °C.
  16. 16. A method for revamping a palladium-containing recovery gauze for recovering volatile platinum and/or rhodium, comprising the step of replacing at least part of the palladium comprised in the recovery gauze for one or more oxide of a rare earth metal selected from the group consisting of Er 2 C>3, Sm 2 C>3 and Yb 2 C>3.

Description

SYSTEM FOR RECOVERING VOLATILE PT AND/OR RH AND METHOD THEREOF TECHNICAL FIELD The present application is in the field of the recovery of volatile precious metals, particularly volatile Pt and/or Rh from a gas phase. BACKGROUND Several reactions require a catalyst to proceed at an acceptable rate and to produce the desired products. Such catalysts are often based upon precious, heavy metals, such as the so-called platinum group metals. The six platinum-group metals are ruthenium (Ru), rhodium (Rh), palladium (Pd), osmium (Os), iridium (Ir), and platinum (Pt). For example, platinum (Pt) and/or rhodium (Rh) are commonly used as catalysts among others in the Ostwald process for nitric acid production, for oxidising ammonia into nitric oxide, and in the Andrussow process for hydrogen cyanide production, for reacting ammonia with oxygen and methane. A problem associated with catalysis using platinum group metals, particularly Pt and/or Rh is that, due the high temperature at which catalysis is performed, for example from 700 to 950 °C or over 1000 °C or over 1100 °C, some of these metals, such as Rh and/or Pt metal evaporate, in particular when the catalysis is performed in the presence of oxygen. The recovery of volatile Pt with, in particular, palladium (Pd)-containing recovery systems is well documented. For example, GB1343637 relates to a process and a related device for recovering platinum metals entrained in a hot gas stream (as in the manufacture of nitric acid) wherein the gas is passed through a gettering device in the form of an inert ceramic honeycomb structure which is coated with a getter containing Pd to absorb the volatile platinum. EP63450 generally discloses a getter device and a related process for recovery of a precious metal lost from a precious metal-containing catalyst operating at elevated temperature, wherein the getter comprises an agglomeration or assemblage of unwoven fibres made from a metal selected from the group ruthenium, palladium, iridium, platinum, gold, silver, rhodium and alloys containing one or more or the said metals. The document primarily focuses on Pd/Au alloys. GB668935 relates to a process and related device for platinum recovery of volatilized platinum, originating from a catalyst. In this context, GB668935 claims a process for recovery of platinum, wherein the platinum is trapped on the surface of baffles, disposed at a place where the temperature is at least 700 °C and wherein some of the baffles have a coating of silver or of a silver alloy with gold, palladium or platinum. LIS20130149207 relates to an exhaust system arrangement comprising a Pt+Pd catalyst and a downstream SCR catalyst and a component capable of trapping and/or alloying with a gas phase platinum group metal, wherein this component is typically a metal selected from the group consisting of gold, palladium and silver, preferably a Pd/Au alloy. On the side of Rh capture, US4774069A discloses a process for the manufacture of nitric oxide by oxidising ammonia in the presence of a catalyst comprising platinum and from 0 to 20 wt % of rhodium and from 0 to 40 wt % of palladium (based on the weight of alloy), the catalyst being located upstream from a catchment trap for scavenging platinum or rhodium lost from the catalyst. The catchment trap comprises an alloy of Pd with at least one compound selected from the group consisting of the oxides, borides, carbides, silicides, nitrides and silicates of aluminum, zirconium, boron, silicon, magnesium, titanium, yttrium, beryllium, thorium, manganese, lanthanum, scandium, calcium, uranium, chromium, niobium and hafnium. The rhodium capture is significantly less documented than platinum capture, which indicates that it is more challenging to achieve. Nonetheless, at the moment the most expensive precious metal is Rh. Thus, it is of great interest to recover as much volatile Rh as possible. There is thus a need in the art for compounds and materials for recovering volatile Pt and/or Rh and that are stable under ambient air. SUMMARY The present application addresses one or more of the above indicated needs. The inventors have surprisingly found that certain oxides of rare earth metals as further defined herein are stable and effective recovery agents for recovering or trapping at least volatile Rh or at least volatile Pt and/or Rh. However, as will be shown in the examples, Yara has established that not all rare earth metal oxides are suitable for recovering volatile Pt and/or Rh. In one aspect of the disclosure, a catalytic system is disclosed. The system comprises: a Pt-containing and/or Rh-containing catalyst; and a recovery system downstream of the catalyst. The system is characterised in that the recovery system comprises one or more oxide of a rare earth metal selected from the group consisting of Er2C>3, So a and Yb2Oa. In particular embodiments, the system is characterised in that the recovery system comprises an oxide of a rare earth metal selected from