Mixed Unsaturated Nitrile Solvents for Nickel Catalyst Solubility
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Solution Overview
Problem
Bidentate phosphorus-containing ligands react more slowly with nickel metals and typically form NiL2A complexes, limiting the solubility and effectiveness of nickel-ligand complexes in hydrocyanation reactions, especially when using single unsaturated nitriles as solvents.
Innovation Solution
A composition of mixed unsaturated nitriles is used to enhance the solubility of nickel-bidentate phosphorus-based ligand complexes, allowing for higher concentrations of active nickel catalysts without the need for Lewis acid promoters, thereby improving the efficiency of hydrocyanation reactions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If bidentate phosphorus-containing ligands are used with nickel metal, then the catalyst can function in hydrocyanation reactions, but the reaction rate is slow and solubility is limited
Solution Approach 1:
The patent changes the solvent parameter from single unsaturated nitriles to mixed unsaturated nitrile compositions. This parameter change increases the solubility of nickel-ligand complexes and accelerates the reaction rate between nickel metal and phosphorus-containing ligands, resolving the contradiction between catalyst functionality and reaction productivity
Solution Approach 2:
The patent uses composite solvent systems comprising multiple unsaturated nitriles (such as mixtures of butyronitrile, valeronitrile, and adiponitrile). This composite approach enhances both the solubility and reactivity of the catalyst system, enabling faster reaction rates while maintaining catalyst functionality
2Reliability
If bidentate phosphorus-containing ligands are used, then NiL2A complexes are formed, but solubility in single unsaturated nitriles is limited
Solution Approach 1:
The patent modifies the solvent composition parameter by using mixed unsaturated nitriles instead of single nitrile solvents. This change significantly increases the solubility of NiL2A complexes formed with bidentate phosphorus-containing ligands, allowing higher concentrations of active catalyst in solution
Solution Approach 2:
The mixed nitrile composition acts as an intermediary medium that facilitates the dissolution of nickel-ligand complexes. The combination of different nitriles creates a solvent environment that better accommodates the NiL2A complex structure, enhancing solubility without requiring Lewis acid promoters
3Quantity of substance
If Lewis acid promoters are used to increase nickel solubility, then catalyst concentration increases, but process complexity increases
Solution Approach 1:
The patent extracts and eliminates the need for Lewis acid promoters from the catalytic system. By using mixed unsaturated nitrile solvents, the system achieves high nickel catalyst concentration and solubility without requiring additional promoter substances, thereby simplifying the overall process
Solution Approach 2:
The mixed unsaturated nitrile solvent system provides self-service by inherently enabling high nickel solubility and catalyst concentration through its composition properties. The solvent mixture itself creates the necessary conditions for high catalyst loading without requiring external promoters or additional process steps
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 use of mixed unsaturated nitriles significantly increases the solubility and concentration of nickel-ligand complexes, leading to higher rates and throughputs of hydrocyanation products like adiponitrile, even in the absence of Lewis acid promoters, thus optimizing industrial-scale hydrocyanation processes.
Implementation Method 1
A composition of mixed unsaturated nitriles is used to enhance the solubility of nickel-bidentate phosphorus-based ligand complexes
Data Source
AI summary
In the hydrocyanation reaction of butadiene proceeding through pentenenitriles to adiponitrile, catalysis by complexes of zerovalent nickel with bidentate phosphorus-based ligands of the NiL2A type wherein L2 is a bidentate ligand and A is an unsaturated compound, can be rate-limited by the solubility of the catalytic complex. The present invention concerns solvent compositions for the nickel-ligand complex comprising mixtures of unsaturated nitriles that provide for increased metal solubility, particularly in the absence of a Lewis acid promoter, resulting in higher hydrocyanation reaction rates in an industrial-scale process for production of important nylon manufacturing intermediates. The mixed nitrile solvent compositions can include mixtures of pentenenitriles and/or methylbutenenitriles. The mixtures of mixed unsaturated nitriles can be, at least in part, from recycle streams from the hydrocyanation reaction for which the nickel-bidentate ligand complexes are used as catalysts.