Multidentate Phosphite Nickel Catalysts for Selective Adiponitrile Synthesis
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Solution Overview
Problem
Existing catalysts for the hydrocyanation of butadiene to produce adiponitrile suffer from low selectivity, high sensitivity to air and moisture, leading to increased costs and complexity in industrial production.
Innovation Solution
The use of a multidentate phosphite ligand-nickel catalyst with a specific structure for the catalytic synthesis of adiponitrile, involving multiple reaction steps and catalysts, enhances selectivity and reduces catalyst usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If monodentate or bidentate phosphite ligands are used in the catalyst, then the catalytic activity is maintained, but the selectivity of main products (3-pentenenitrile and adiponitrile) is insufficient and the catalyst requires large amounts with high sensitivity to air and moisture
Solution Approach 1:
The patent employs a multidentate phosphite ligand with a specific composite structure containing multiple phosphite groups coordinated to a nickel center. This composite ligand structure provides both high selectivity for main products and improved stability against air and moisture, resolving the contradiction between selectivity and reliability.
Solution Approach 2:
The multidentate phosphite ligand features specific local structural characteristics including multiple phosphite coordinating groups positioned to optimize catalytic selectivity while the overall ligand framework provides protective effects against air and moisture. This local quality enhancement at the active site combined with global structural stability achieves both high selectivity and reliability.
2Productivity
If monodentate or bidentate phosphite ligands are used, then the catalyst can function, but the amount of catalyst required is large and the production cost increases
Solution Approach 1:
The patent changes the key parameter of ligand denticity from monodentate or bidentate to multidentate (specifically tridentate or tetradentate). This parameter change dramatically improves catalytic efficiency, allowing the reaction to proceed with much lower catalyst loading while maintaining or enhancing productivity, thus resolving the contradiction between productivity and quantity of substance.
3Manufacturing precision
If existing complex catalysts are used for hydrocyanation, then the reaction can proceed, but the selectivity and catalytic activity have room for improvement
Solution Approach 1:
The patent optimizes the local quality of the catalyst by designing a multidentate phosphite ligand with specific coordinating groups positioned to maximize selectivity for the desired hydrocyanation products. The ligand structure features multiple phosphite groups in specific geometries that create a selective catalytic environment, achieving high selectivity without excessive overall complexity.
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 multidentate phosphite ligand-nickel catalyst achieves high selectivity (up to 94.2%) and reduces catalyst consumption, lowering production costs and facilitating industrialization.
Implementation Method 1
The multidentate phosphite ligand-nickel catalyst achieves high selectivity (up to 94.2%) and reduces catalyst consumption, lowering production costs and facilitating industrialization
Data Source
AI summary
The present disclosure relates to a use of a multidentate phosphite ligand in the catalytic synthesis of adiponitrile. The ligand is represented by the following general formula (I). The method of catalytic synthesis of adiponitrile comprises primary hydrocyanation, isomerization, and secondary hydrocyanation reactions, wherein the catalyst adopted each comprises a phosphite ligand-nickel complex composed of a nickel precursor and a multidentate phosphite ligand. The ligand molecule has a higher electron cloud density, and the phosphorus content capable of participating in coordination in the ligand molecule per unit mass is higher, so that the catalytic activity of the catalyst is improved, and the amount of the catalyst is reduced. Meanwhile, the steric and spatial configuration of the phosphite ligand-nickel complex may be adjusted by designing and optimizing the framework structure of the ligand, and the chemical environment and the steric effect around a metal center may be changed by the designing and optimizing mentioned above combine with flexibly regulating the electronic effect and the steric hindrance effect of a substituent on the molecular structure of the ligand, so that the selectivity of a linear product adiponitrile is improved.