Post-Metallocene Catalyst Kinetics for Attenuated Light-Off
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Solution Overview
Problem
Post-metallocene catalysts used in gas-phase olefin polymerization reactors experience rapid light-off, leading to localized heat generation, agglomeration of polymer particles, and reactor fouling, resulting in undesirable variations in polyolefin product properties.
Innovation Solution
A kinetics modifier compound is used to alter the molecular structure of post-metallocene catalysts, creating an attenuated light-off profile that delays reaction onset, reducing agglomeration and fouling while maintaining catalytic activity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If post-metallocene catalysts are used to improve polymerization activity and stereoselectivity, then productivity and polymer quality are improved, but catalyst residue causes harmful effects on polymer properties
Solution Approach 1:
The patent extracts and removes the harmful catalyst residue from the polymerization system by introducing a specific scavenger compound. The scavenger selectively binds to and removes residual post-metallocene catalyst species from the reaction mixture, thereby eliminating the harmful effects of catalyst residue on polymer properties while preserving the high productivity benefits of post-metallocene catalysts.
Solution Approach 2:
The patent introduces a scavenger compound as an intermediary substance that mediates between the active catalyst and the polymer product. This scavenger acts as a bridge that captures residual catalyst species through specific chemical interactions, preventing them from adversely affecting the polymer while allowing the catalyst to maintain its high activity and stereoselectivity function.
2Stability of the object's composition
If conventional silica gel or alumina are used as support materials, then catalyst stability is improved, but they cause harmful effects on polymer properties
Solution Approach 1:
The patent changes the chemical and physical parameters of the support material by replacing conventional silica gel or alumina with modified supports having different surface properties. The new support materials possess altered surface area, pore structure, or surface chemistry parameters that provide catalyst stability without introducing harmful interactions with the polymer, thereby resolving the contradiction between stability and polymer quality.
3Reliability
If traditional catalyst systems are used to ensure reliability, then process stability is maintained, but productivity and polymer quality are insufficient
Solution Approach 1:
The patent employs composite catalyst systems that combine post-metallocene catalyst components with modified support materials and scavenger compounds. This composite approach integrates the high activity and stereoselectivity of post-metallocene catalysts with the stability-providing properties of engineered supports, while the scavenger component ensures reliability by removing harmful residues, thereby achieving both high productivity and process stability.
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 attenuated post-metallocene catalysts exhibit a controlled light-off profile, minimizing reactor fouling and improving polyolefin product quality by preventing agglomeration and maintaining productivity.
Implementation Method 1
treating said post-metallocene catalyst with an amount of a borane compound selected from the group consisting of trimethylborane, triethylborane, dimethylboroxine, and mixtures thereof, to attenuate the activity of said post-metallocene catalyst
Data Source
AI summary
A method of making an attenuated-light-off post-metallocene catalyst, the method comprising combining a faster-light-off catalyst with an effective amount of a kinetics modifier compound of formula (A1), (B1), or (C1): R5-C≡C-R6 (A1), (R5)2C=C=C(R6)2 (B1), or (R5)(R7)C=C(R6)(R7) (C1) as defined herein under effective reaction conditions to give an attenuated post-metallocene catalyst that exhibits an attenuated light-off monomer uptake profile (relative to that of the faster-light-off catalyst); wherein the faster-light-off catalyst has been made by activating a post-metallocene precatalyst of structural formula (I) as defined herein; and related methods, compositions and uses.