Supercritical Fluid Extraction of Platinum Group Metals from Ceramic Supports
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Solution Overview
Problem
Current methods for recycling platinum group metals (PGMs) from ceramic supports in heterogeneous catalysts often destroy the supports and require costly purification and reduction steps, leading to inefficient extraction and waste generation.
Innovation Solution
A process using a supercritical fluid extraction medium with a metal-selective organic ligand, such as dodecanethiol, that forms a homogeneous complex with PGMs in their metallic state, allowing direct extraction and recovery without damaging the supports or needing purification and reduction steps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If pyrometallurgical processes or wet chemical etching with acid are used to extract PGMs, then PGM recovery is achieved, but the ceramic supports are destroyed and waste is generated
Solution Approach 1:
The patent changes the physical-chemical parameters of the extraction medium by using supercritical CO2 instead of conventional acids or pyrometallurgical conditions. This parameter change allows extraction at milder conditions that preserve the ceramic support structure while still achieving effective PGM recovery through the addition of chelating agents that form soluble complexes with the metals.
Solution Approach 2:
The patent introduces chelating agents as intermediary substances that mediate between the supercritical CO2 and the PGMs. These ligands form soluble complexes with the metal particles, enabling their extraction into the supercritical phase without requiring destructive conditions. The chelating agents act as intermediaries that facilitate selective metal extraction while leaving the support intact.
2Quantity of substance
If conventional extraction methods are used, then PGMs can be recovered, but purification and reduction steps are required which increase process complexity and cost
Solution Approach 1:
The patent merges the extraction and purification steps into a single operation. By using supercritical CO2 with chelating agents, the method achieves selective extraction of PGMs directly in their recovered form, eliminating the need for separate purification and reduction steps. The chelating agents ensure that only PGMs are extracted along with minimal support contamination, combining what were previously separate operations.
3Stability of the object's composition
If supercritical CO2 with ligands is used for extraction, then support preservation is achieved, but extraction efficiency and selectivity need improvement
Solution Approach 1:
The patent applies local quality by using specific chelating agents with tailored molecular structures that have high affinity for PGMs. Different ligands are selected based on their specific binding characteristics to target particular metal types and oxidation states. This localized chemical specificity enhances extraction efficiency and selectivity for certain PGMs while maintaining support preservation, allowing optimization for specific application requirements.
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
This method enables efficient and selective extraction of PGMs in their metallic form, reducing the number of steps, duration, and cost, while preserving the ceramic supports for reuse and improving extraction efficiency compared to existing methods.
Implementation Method 1
a process using a supercritical fluid extraction medium with a metal-selective organic ligand, such as dodecanethiol, that forms a homogeneous complex with PGMs in their metallic state
Data Source
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AI summary
Method of selective extraction of a metal from the family of platinoids, from a ceramic support containing said metal, comprising the following successive steps : a) said ceramic support containing said metal is brought into contact, in an extraction chamber, with an extraction medium consisting of a pressurized dense fluid containing an organic ligand that is selective for the metal and that is capable of forming a complex with said metal in the 0 state; obtained whereby are, on the one hand, a ceramic support depleted in said metal, or even free of said metal, and, on the other hand, a medium consisting of the pressurized dense fluid containing the complex of the organic ligand with the metal in the 0 state; b) said pressurized dense fluid containing the complex of the organic ligand with the metal in the 0 state is brought to atmospheric pressure and to ambient temperature, whereby the complex of the organic ligand with the metal in the 0 state separates from the fluid; c) the ceramic support depleted in said metal or even free of said metal, and the complex of the organic ligand with the metal in the 0 state, are recovered.