Rare Earth Oxide Catalyst Recovery via Selective Dissolution
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Solution Overview
Problem
Current recycling processes for catalysts containing rare earth oxides and noble metals are energy-intensive, generate toxic effluents, and do not efficiently recover rare earth elements like cerium, making them environmentally and economically inefficient.
Innovation Solution
A selective dissolution process using a mineral acid and a natural antioxidant reducing agent, such as ascorbic acid, to dissolve rare earth oxides at moderate temperatures and pressures, allowing for the separation and recovery of rare earth metals and noble metals from the substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If traditional hydrometallurgical processes use powerful leaching agents to dissolve rare earth oxides, then dissolution efficiency is improved, but environmental pollution and toxicity of effluents worsen
Solution Approach 1:
The invention changes the chemical parameters of the dissolution system by replacing traditional strong oxidizing agents (H2O2, NaClO, NH4ClO4) with ascorbic acid as the reducing agent. This parameter change transforms the dissolution mechanism while maintaining high dissolution efficiency, and the resulting effluents are non-toxic and environmentally friendly, directly resolving the contradiction between dissolution efficiency and environmental pollution
Solution Approach 2:
Ascorbic acid is used as a disposable reducing agent that is cheap, biodegradable, and environmentally friendly. It is consumed during the dissolution process and can be easily disposed of without causing environmental harm, unlike persistent toxic chemicals in traditional methods. This principle resolves the contradiction by providing a low-cost, eco-friendly alternative that maintains effectiveness
2Reliability
If pyrometallurgical processes are used to recycle catalysts, then noble metal recovery is improved, but energy consumption worsens
Solution Approach 1:
The invention replaces the thermal/chemical system of pyrometallurgy (high-temperature melting and reduction) with a chemical dissolution system using ascorbic acid. This substitution eliminates the need for high-temperature furnaces and complex thermal processing, dramatically reducing energy consumption while maintaining effective noble metal recovery through selective dissolution and filtration
Solution Approach 2:
The invention changes the operating parameters from high-temperature conditions (pyrometallurgy) to ambient or mild temperature conditions (chemical dissolution). This parameter change transforms the process from energy-intensive to energy-efficient, while the selective dissolution mechanism ensures high noble metal recovery rates
3Manufacturing precision
If selective dissolution of rare earth oxide support is achieved, then separation of noble metals is improved, but dissolution conditions become more restrictive
Solution Approach 1:
Ascorbic acid acts as an intermediary reducing agent that facilitates the selective dissolution of rare earth oxides without affecting noble metals. It mediates the chemical reaction by providing a controlled reducing environment that selectively attacks the oxide support while leaving noble metal particles intact, achieving high separation selectivity under simple conditions
Solution Approach 2:
The invention changes the dissolution conditions to use mild, ambient temperature and pressure with ascorbic acid solution, replacing complex high-temperature or strong acid conditions. This parameter change simplifies the dissolution conditions while maintaining high separation selectivity between rare earth oxides and noble metals
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 achieves complete and selective dissolution of rare earth oxides under mild conditions, reducing energy consumption and environmental impact, and enables the recovery of both rare earth and noble metals, improving recycling efficiency.
Implementation Method 1
a step of selective dissolution of the support, during which the substrate is brought into contact with a dissolution solution comprising at least one mineral acid and at least one reducing agent, in order to dissolve the rare earth or rare earths of the support
Implementation Method 2
a dissolution solution comprising at least one mineral acid and at least one reducing agent
Data Source
Figure 1A~1B
Figure 2A~2D
Figure 3A~3B
AI summary
A method for treating a solid substrate comprising a support comprising, preferably consisting of, at least one oxide chosen from the oxides of a first metal chosen from the rare earths, the mixed oxides of a first metal chosen from the rare earths and at least one second metal different from the first metal, and the mixtures of an oxide of a first metal chosen from the rare earths and at least one oxide of at least one second metal different from the first metal, said support comprising at least one surface on which there are deposited particles consisting of at least one noble metal, in order to separate the first metal, the optional second metal, and the noble metal which constitutes the particles, said method comprising a step of selectively dissolving the support, during which the substrate is brought into contact with a dissolving solution comprising at least one mineral acid and at least one reducing agent for reducing the rare earth or rare earths of the support chosen from natural antioxidant molecules such as ascorbic acid, catechol, gallic acid and the mixtures of same, thereby obtaining a solution containing the first metal and the possible second metal in the dissolved state, in which there are suspended the particles consisting of the noble metal.