Distillation Control for Solvent-Nickel Catalyst Separation
Solution Overview
Problem
The existing processes for producing adiponitrile (ADN) face challenges in efficiently separating catalysts containing nickel and bidentate phosphorus-containing ligands, particularly due to isomerization of 3-pentenenitrile to 2-methyl-3-butenenitrile in distillation column bottoms, which leads to yield loss and catalyst inefficiency.
Innovation Solution
A method is introduced to control the ratio of 2-pentenenitrile to 3-pentenenitrile in the distillation zone, where the catalyst solution comprising nickel and a bidentate phosphorus-containing ligand is subjected to distillation conditions to form a solvent-depleted catalyst solution, with a targeted ratio of 3-pentenenitrile to 2-pentenenitrile of 14 or less, thereby reducing unwanted isomerization and enhancing catalyst concentration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If distillation is used to separate solvent from catalyst, then solvent removal is achieved, but isomerization of 3-pentenenitrile to 2-methyl-3-butenenitrile occurs causing yield loss
Solution Approach 1:
The patent changes the chemical composition parameters of the distillation system by adding 2-pentenenitrile as an intermediate boiler and adjusting the nickel catalyst to bidentate phosphorus ligand complex. This modifies the distillation behavior to reduce isomerization while maintaining separation efficiency
Solution Approach 2:
2-pentenenitrile is introduced as an intermediate boiler that mediates the distillation process. It has a boiling point between the solvent and catalyst components, allowing it to act as a buffer that reduces thermal stress on 3-pentenenitrile and minimizes isomerization to 2-methyl-3-butenenitrile
2Productivity
If high temperature distillation is used to remove solvent, then separation efficiency increases, but catalyst degradation and isomerization increase
Solution Approach 1:
The patent changes the boiling point parameters of the system by introducing 2-pentenenitrile with intermediate volatility. This creates a stepped distillation profile that allows solvent removal at lower temperatures, preventing catalyst degradation and isomerization while maintaining separation productivity
Solution Approach 2:
The patent uses 2-pentenenitrile as a substitute intermediate that copies the functional role of traditional intermediate boilers but with optimized properties for reducing isomerization. It serves as a proxy substance that protects the main catalyst system from thermal stress
3Quantity of substance
If conventional distillation conditions are used, then solvent removal is achieved, but 3-pentenenitrile isomerizes to 2-methyl-3-butenenitrile
Solution Approach 1:
2-pentenenitrile acts as an intermediary substance that stabilizes the composition during distillation. Its presence creates a buffer zone in the distillation column that prevents direct thermal contact between 3-pentenenitrile and high-temperature zones, maintaining compositional stability
Solution Approach 2:
The patent modifies the compositional parameters by adding 2-pentenenitrile and adjusting the nickel to bidentate phosphorus ligand complex ratio. These parameter changes shift the distillation equilibrium to favor solvent removal while suppressing isomerization reactions
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 effectively minimizes the isomerization of 3-pentenenitrile to 2-methyl-3-butenenitrile, thereby increasing adiponitrile yield and maintaining catalyst efficiency by concentrating the catalyst solution while optimizing distillation conditions.
Implementation Method 1
A method is introduced to control the ratio of 2-pentenenitrile to 3-pentenenitrile in the distillation zone, where the catalyst solution comprising nickel and a bidentate phosphorus-containing ligand is subjected to distillation conditions to form a solvent-depleted catalyst solution
Implementation Method 2
the catalyst solution comprising nickel and a bidentate phosphorus-containing ligand is subjected to distillation conditions to form a solvent-depleted catalyst solution
Data Source
AI summary
A solvent is at least partially separated from a catalyst. The catalyst comprises nickel and a bidentate phosphorus-containing ligand. The method for separation involves distilling a catalyst solution. The ratio of 2-pentenenitrile to 3-pentenenitrile in distillation column bottoms is controlled to reduce the amount of 3-pentenenitrile which is isomerized to form 2-methyl-3-butenenitrile. Isomerization of 3-pentenenitrile to 2-methyl-3-butenenitrile and subsequent isomerization of 2-methyl-3-butenenitrile to 2-methyl-2-butenenitrile, and/or hydrocyanation of 2-methyl-3-butenenitrile to methylglutaronitrile represents a loss in adiponitrile yield in a process for making adiponitrile.