Cobalt Catalyst Recycling via Aqueous Extraction
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Solution Overview
Problem
Current hydroformylation processes face challenges in efficiently recovering and recycling cobalt catalysts, particularly due to limitations in water solubility, complex preforming and carbonyl extraction steps, and high equipment costs, which result in suboptimal catalyst recovery and environmental concerns.
Innovation Solution
A two-step demetalling process is implemented, involving an initial extraction of cobalt carbonyls into an aqueous phase using a salt of a second metal and a first acid with a pKa of at least 1.5, followed by an air demetalling step to decompose remaining cobalt carbonyls, allowing direct recycling of the cobalt catalyst to the hydroformylation reaction without the need for complex intermediate extraction or preforming steps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional cobalt catalyst recovery processes are used, then cobalt catalyst can be recovered from hydroformylation reaction, but the process requires complex preforming and carbonyl extraction steps with high equipment costs
Solution Approach 1:
The patent extracts cobalt catalyst from the organic reaction product directly into an aqueous phase using a salt solution, eliminating the need for complex preforming and carbonyl extraction steps. The cobalt is removed as a salt complex that can be directly recycled, simplifying the overall process flow and reducing equipment requirements.
Solution Approach 2:
The patent changes the chemical parameters by using a salt of a second metal with a specific acid (pKa ≥ 1.5) to alter the solubility and extraction efficiency of cobalt. This parameter change enables direct extraction without complex intermediate steps, reducing process complexity while maintaining reliable catalyst recovery.
2Reliability
If traditional demetalling processes are used, then cobalt catalyst is removed from reaction product, but water usage is high and volume efficiency is suboptimal
Solution Approach 1:
The patent optimizes the aqueous phase composition by using a salt solution with specific acid characteristics (pKa ≥ 1.5), which improves extraction efficiency and reduces the volume of water required for effective cobalt removal, enhancing both reliability and resource efficiency.
3Reliability
If complex intermediate extraction steps are implemented, then cobalt catalyst recovery is improved, but equipment size and processing time increase
Solution Approach 1:
The patent implements a direct extraction mechanism that removes cobalt catalyst in a single step without complex intermediate processes, significantly reducing processing time while maintaining high recovery efficiency through optimized salt solution composition.
Solution Approach 2:
The patent prepares the aqueous salt solution with specific characteristics in advance, enabling immediate and efficient cobalt extraction upon contact with the reaction product, eliminating the need for time-consuming intermediate steps and equipment operations.
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 approach enhances volume efficiency, reduces equipment size, and minimizes water usage, while avoiding induction times in the preforming reaction, resulting in a more streamlined and environmentally friendly catalyst recovery process.
Implementation Method 1
contacting the organic cobalt catalyst-containing reaction product with an aqueous solution of a salt of a second metal and a first acid to form an aqueous solution comprising a salt of the second metal having cobalt carbonyl as anion
Implementation Method 2
contacting the organic reaction product separated in step (b), in the presence of an oxygen-containing gas or an oxygen-donating compound, with an aqueous solution of a second acid to form an aqueous solution comprising a cobalt salt of the second acid
Data Source
Figure 1
AI summary
An improved hydroformylation catalyst cycle is disclosed wherein the cobalt catalyst is recycled to the hydroformylation reaction mainly as a water soluble carbonyl salt, obtained from extraction of the acidic form of the homogeneous cobalt carbonyl catalyst from the hydroformylation product with an aqueous solution of a salt of a weaker acid. The organic product after extraction is submitted to a further demetalling step in the presence of a dilute acid and an oxidant. The water from this further demetalling step is suitable for use in the upstream extraction step. A free water phase present in the hydroformylation reaction product may be separated upstream from the extraction step and is suitable for use in the further demetalling step, such that the catalyst cycle has no waste water stream.