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 suboptimal polymer properties for specific applications.
Innovation Solution
A chromium-based catalyst composition is developed, comprising an inorganic oxide-supported chromium catalyst, a particulate material with an average particle size of less than 5 microns, and/or an antistatic agent, which minimizes particle aggregation and improves dispersion, resulting in consistent flow index responses and enhanced polymer properties.
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
Solution Approach 1:
An organometallic compound (intermediary substance) is introduced to modify the chromium-based catalyst, creating a new catalyst system that combines the high productivity of chromium oxide-on-silica with the ability to produce broader molecular weight distributions suitable for blow molding applications
Solution Approach 2:
The catalyst system parameters are changed by adding organometallic compounds and adjusting preparation conditions (drying temperature, reducing agent addition time) to achieve both high productivity and desirable molecular weight distribution characteristics
2Stability of the object's composition
If silyl chromate-based catalysts are used, then molecular weight characteristics are improved, but productivity decreases
Solution Approach 1:
The invention merges the advantages of silyl chromate catalysts (broad molecular weight distribution) with chromium oxide-on-silica catalysts (high productivity) by using organometallic compounds to modify the chromium-based catalyst system, achieving both desired molecular weight characteristics and high productivity
Solution Approach 2:
A composite catalyst system is created by combining chromium-based catalyst components with organometallic compounds, resulting in a catalyst that exhibits both high productivity and broad molecular weight distribution suitable for blow molding applications
3Productivity
If chromium-based catalysts are used, then polyolefin production is achieved, but flow index response varies between batches
Solution Approach 1:
The invention establishes controlled preparation procedures with specific parameters (drying temperature ranges, reducing agent addition times, organometallic compound ratios) that provide feedback control over catalyst properties, ensuring consistent flow index responses across batches
Solution Approach 2:
The catalyst preparation includes preliminary steps (drying at controlled temperatures, controlled addition of reducing agents and organometallic compounds) that pre-establish consistent catalyst properties before polymerization, reducing batch-to-batch variation in flow index responses
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 improved homogeneity and batch-to-batch consistency, reducing variations in flow index responses and enabling the production of polymers with desired molecular weight ranges, thus facilitating the production of polyolefins with specific properties for various applications.
Implementation Method 1
heated in the presence of oxygen to about 400° C.-860° C., converting most or all of the chromium from the +3 to the +6 oxidation state
Implementation Method 2
contacting the activated chromium-based catalyst with an organometallic compound
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.