Chromium Catalyst Composition for Consistent Flow Index
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Chromium-based catalysts used in polyolefin manufacture often produce polymers with inconsistent flow index responses, leading to variations in molecular weight and processing characteristics, which can result in operational difficulties and undesirable polymer properties.
Innovation Solution
A chromium-based catalyst composition is developed, comprising thermally treated particulate material with chromium compounds, aluminium alkyl species, and a hydrophobic particulate material like treated fumed silica, which minimizes particle agglomeration and improves dispersion, thereby enhancing batch consistency and reducing flow index variation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If chromium oxide-on-silica catalysts are used, then productivity is improved, but molecular weight distribution becomes narrower than desired
Solution Approach 1:
The patent combines chromium oxide-on-silica catalyst (providing high productivity) with silyl chromate catalyst (providing desirable molecular weight distribution characteristics) into a single composite catalyst system, thereby achieving both high productivity and broad molecular weight distribution simultaneously
2Stability of the object's composition
If silyl chromate-based catalysts are used, then molecular weight distribution becomes broader, but productivity decreases
Solution Approach 1:
The patent combines chromium oxide-on-silica catalyst (providing high productivity) with silyl chromate catalyst (providing desirable molecular weight distribution characteristics) into a single composite catalyst system, thereby achieving both high productivity and broad molecular weight distribution simultaneously
3Productivity
If chromium-based catalysts are used without modification, then catalytic activity is maintained, but flow index response becomes inconsistent
Solution Approach 1:
The patent introduces a reducing agent as an intermediary substance that modifies the chromium-based catalyst surface, creating intermediate species that provide consistent flow index response while maintaining high catalytic activity for polyolefin production
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 composition achieves consistent flow index responses, improving the homogeneity and bulk density of the catalyst, leading to more reliable polymer production with desired properties, such as higher molecular weight and improved processing characteristics.
Implementation Method 1
The thermally treated particulate material is treated at an elevated temperature to convert chromium atoms into the +6 state and/or to remove moisture
Implementation Method 2
treating the thermally treated particulate material with a reducing agent
Data Source
AI summary
Modified chromium-based catalyst compositions for olefin polymerization are disclosed. The modifiers prevent or reduce catalyst particle aggregation providing improved catalyst particle dispersion and consistent flow index response of the compositions in olefin polymerization.