Hydrogenated Nitrile Rubber Catalyst System for Molecular Weight Control
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Solution Overview
Problem
Current methods for producing hydrogenated nitrile rubber polymers result in high molecular weights and broad molecular weight distributions, with ruthenium-based catalysts often causing crosslinking and high Mooney viscosity, and existing metathesis catalysts are not suitable for simultaneous hydrogenation and degradation of nitrile rubber.
Innovation Solution
A process involving simultaneous hydrogenation and metathesis of nitrile butadiene rubber in the presence of hydrogen and a catalyst of specific formulae, such as (I), (II), or (III), which includes ruthenium or osmium, anionic and neutral electron donor ligands, and substituents, to achieve lower molecular weights and narrower distributions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If ruthenium-based catalysts are used for hydrogenation of nitrile rubber, then hydrogenation efficiency is improved, but crosslinking occurs leading to high Mooney viscosity and gelling
Solution Approach 1:
The patent introduces a specific ruthenium catalyst complex with carefully selected ligands (combination of phosphine and nitrogen-containing ligands) as an intermediary that enables hydrogenation while preventing direct interaction between the catalyst and nitrile groups that would cause crosslinking. The ligand sphere acts as a mediator controlling the catalyst's reactivity profile.
Solution Approach 2:
The patent modifies the catalyst parameters by selecting specific ligand types and ratios (phosphine to nitrogen ligand ratio between 1:4 and 4:1), steric bulk, and electronic properties to tune the catalyst's behavior. This parameter optimization allows efficient hydrogenation while suppressing unwanted side reactions.
2Reliability
If conventional hydrogenation is used to produce HNBR, then hydrogenation is achieved, but molecular weight is high and molecular weight distribution is broad
Solution Approach 1:
The patent combines hydrogenation and metathesis reactions into a single simultaneous process using a dual-functional catalyst system. The metathesis component breaks down high molecular weight chains while hydrogenation saturates double bonds, achieving both complete hydrogenation and precise molecular weight control in one operation.
Solution Approach 2:
The patent changes the reaction parameters by introducing metathesis catalysts alongside hydrogenation catalysts, optimizing the ratio and conditions to achieve simultaneous reactions that produce narrow molecular weight distributions while maintaining complete hydrogenation.
3Manufacturing precision
If existing metathesis catalysts are used for nitrile rubber degradation, then molecular weight reduction is achieved, but they are not suitable for simultaneous hydrogenation
Solution Approach 1:
The patent employs a catalyst system that performs multiple functions simultaneously: the ruthenium-based metathesis catalyst reduces molecular weight while the same or complementary catalyst system enables hydrogenation. This multi-functional approach eliminates the need for separate reaction steps.
Solution Approach 2:
The patent uses specific ligand systems as intermediaries that enable the catalyst to perform both metathesis and hydrogenation functions. The ligand environment mediates the catalyst's ability to facilitate different reaction types without deactivation or side 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
The process produces hydrogenated nitrile rubber with lower molecular weights (20,000 to 250,000 g/mol), reduced Mooney viscosity (1 to 50), and polydispersity index less than 2.8, suitable for various industrial applications with improved processing properties.
Implementation Method 1
A process involving simultaneous hydrogenation and metathesis of nitrile butadiene rubber in the presence of hydrogen and a catalyst
Implementation Method 2
A process involving simultaneous hydrogenation and metathesis of nitrile butadiene rubber in the presence of hydrogen and a catalyst of specific formulae
Data Source
AI summary
The present invention relates to a process for the production of hydrogenated nitrile rubber polymers having lower molecular weights and narrower molecular weight distributions than those known in the art, wherein the process is carried out in the presence of hydrogen and optionally at least one co-olefin. The present invention further relates to the use of specific metal compounds in a process for the production of a hydrogenated nitrile rubber by simultaneous hydrogenation and metathesis of a nitrile rubber.