Phosphinimine Catalyst System for Olefin Polymerization Reactor Continuity
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Solution Overview
Problem
Single-site catalysts for olefin polymerization exhibit high initial activity followed by rapid decline, leading to reduced reactor continuity and potential fouling issues due to static and kinetic profile fluctuations, which existing technologies fail to adequately address.
Innovation Solution
A catalyst system comprising a porous inorganic oxide support treated with Zr(SO4)2.4H2O, an aluminum activator, and a phosphinimine ligand-based catalyst, combined with an antistatic agent to stabilize the kinetic profile and reduce static, resulting in improved reactor continuity and catalyst activity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If single-site catalysts are used for olefin polymerization, then catalyst activity is improved, but reactor continuity deteriorates due to rapid decline in activity and fouling
Solution Approach 1:
The patent modifies the catalyst system by changing the ligand parameters - specifically using phosphinimine ligands with specific substituents (R1-R6) and combining them with heteroatom ligands (N, S, B, O, P, or Si). This chemical parameter change transforms the kinetic profile to maintain higher activity over extended periods, resolving the contradiction between initial activity and sustained reactor continuity.
Solution Approach 2:
The patent employs composite catalyst systems combining phosphinimine ligands with heteroatom ligands on supported catalyst structures. This composite approach creates a synergistic effect that maintains catalyst activity while reducing the rapid decline characteristic of single-site catalysts, thereby improving both productivity and reactor continuity.
2Productivity
If catalyst activity is increased, then polymer production rate is improved, but kinetic profile stability deteriorates leading to fouling
Solution Approach 1:
The patent systematically varies ligand parameters including the heteroatom type (N, S, B, O, P, or Si) and the organic substituents on the phosphinimine ligand. These parameter changes allow tuning of the kinetic profile to achieve both high polymer production rates and stability, preventing the rapid activity decline that causes fouling.
Solution Approach 2:
The patent references and builds upon existing catalyst designs (such as U.S. Pat. No. 6,147,172 and Canadian Patent Application 2,716,772) by modifying and improving upon them. The invention copies the successful elements of prior art while adding the phosphinimine ligand component that stabilizes the kinetic profile, achieving both high productivity and stability.
3Productivity
If catalyst activity is maintained high, then productivity is improved, but static accumulation increases causing fouling
Solution Approach 1:
The patent converts the potentially harmful effect of high catalyst activity (which generates static) into a beneficial outcome by using phosphinimine ligands with specific substituents that stabilize the kinetic profile. This allows maintaining high productivity while the stabilized profile prevents the static accumulation that would normally occur with rapid activity changes.
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 catalyst system maintains high activity with a stable kinetic profile, reducing fouling and static, and achieving a polymer production rate greater than 1,300 g/g/hour with a controlled ethylene consumption ratio, enhancing reactor continuity and catalyst longevity.
Implementation Method 1
A catalyst system comprising a porous inorganic oxide support treated with Zr(SO4)2.4H2O, an aluminum activator, and a phosphinimine ligand-based catalyst
Implementation Method 2
combined with an antistatic agent to stabilize the kinetic profile and reduce static
Data Source
AI summary
A supported catalyst system comprising a phosphinimine ligand containing catalyst on a porous inorganic support treated with a metal salt has improved reactor continuity in a dispersed phase reaction in terms of initial activation and subsequent deactivation. The resulting catalyst has a lower consumption of ethylene during initiation and a lower rate of deactivation. Preferably the catalyst is used with an antistatic agent.