Low-Halogen PGM Complex Synthesis via Ligand Exchange
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Solution Overview
Problem
Current methods for producing low-halogen platinum group metal (PGM) compounds are costly and complex, often resulting in high residual halogen contents, which are undesirable due to corrosion, health hazards, and environmental concerns, and existing processes are inefficient and time-consuming.
Innovation Solution
A process involving the reaction of hydroxo complexes of platinum, palladium, and rhodium with uncharged donor ligands to replace hydroxo groups, achieving low-halogen PGM complexes with controlled halogen content and pH, using elevated temperatures and extended reaction times to ensure ligand exchange and maintain coordination numbers, allowing for the production of novel PGM complexes with reduced halogen content.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If conventional methods are used to produce low-halogen PGM compounds, then halogen content is reduced, but the process becomes costly and complex with high residual halogen contents
Solution Approach 1:
The patent extracts and removes halogen atoms from PGM compounds through a two-stage process: first converting PGM halides to hydroxo complexes, then reacting with uncharged donor ligands to replace remaining hydroxo groups and eliminate halogen residues, achieving low-halogen products without complex purification equipment
Solution Approach 2:
The patent performs preliminary conversion of PGM halides to hydroxo complexes before the main ligand exchange reaction. This preliminary action facilitates subsequent halogen removal by creating a more reactive intermediate that readily exchanges ligands, simplifying the overall process
2Object-affected harmful factors
If conventional methods are used to produce low-halogen PGM compounds, then halogen content is reduced, but production time increases and efficiency decreases
Solution Approach 1:
The patent implements continuous useful action through a streamlined two-stage process where the first stage produces hydroxo complexes that directly feed into the second stage ligand exchange reaction. This continuous flow without intermediate isolation steps maintains high productivity while achieving low halogen content
Solution Approach 2:
The patent utilizes parameter changes by conducting reactions at elevated temperatures (60-110°C) and controlling pH levels (2-12) to accelerate ligand exchange kinetics. These parameter optimizations reduce reaction times while ensuring complete halogen removal, thereby improving production efficiency
3Ease of manufacture
If chloride-containing PGM compounds are used, then production is simpler and cheaper, but corrosion and health hazards increase
Solution Approach 1:
The patent converts the harmful chloride ions into useful hydroxo complexes through controlled hydrolysis. The chloride-containing starting materials are transformed into hydroxo complexes that serve as ideal intermediates for ligand exchange, turning a hazardous component into a beneficial reaction intermediate
Solution Approach 2:
The patent introduces hydroxo complexes as intermediary species between chloride-containing starting materials and final low-halogen products. These intermediates facilitate the removal of harmful chloride ions while maintaining production simplicity, acting as a bridge that enables safe transformation
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The process effectively reduces halogen content in PGM compounds, achieving low-halogen products with controlled pH and improved solubility, addressing the inefficiencies and costs of existing methods while providing novel complexes suitable for industrial applications.
Implementation Method 1
the reaction of hydroxo complexes of platinum, palladium, and rhodium with uncharged donor ligands to replace hydroxo groups, achieving low-halogen PGM complexes with controlled halogen content and pH
Implementation Method 2
using elevated temperatures and extended reaction times to ensure ligand exchange and maintain coordination numbers
Data Source
AI summary
The invention relates to a method for producing aqueous preparations of complexes of platinum group metals (PGM) Pt, Pd, Rh and Ir having the general formula [MA/MB/MC (L)a (H2O)b (O2−)c(OH−)d](OH—)e(H+)f, wherein MA=PtII or PdII, MB=PtIV, MC=Rh or Ir, L is a neutral monodentate or bidentate donor ligand, and a is an integer between 1 and 4 (or 2) and/or between 1 and 6 (or 3), b is an integer between 0 and 3 (or 5), c is an integer between 0 and 3 (or 4), d is an integer between 0 and 3 (or 5), e is an integer between 0 and 2 (or 3 or 4) and f is an integer between 0 and 4 (or 5). In the method according to the invention, the hydroxo complexes H2Pd(OH)4 (in the case of MA=PdII), H2Pt(OH)6 (in the case of MA=PtII and MB=PtIV) or H3MC(OH)6 (for MC=RhIII IrIII) are converted in the presence of the donor ligands, wherein at least one hydroxo group of the hydro complex is exchanged. Preferably, the reaction occurs at temperatures in the range of 40 to 110° C. with a reaction time of between 2 and 24 hours, wherein, where MA=PtII, the conversion additionally occurs in the presence of a reduction agent. The method optionally further comprises an exchange of OH anions bound outside of the complex sphere with other anions (e.g. hydrogen carbonate or carbonate anions). The aqueous preparations contain PGM complexes such as [Pt(en)2](OH)2, [Pt(EA)4](OH)2 or [Rh(NH3)6](OH)3 and are used to produce electroplating baths, heterogeneous catalysts or metal powders, for example.