Rapid Activation of Chromium-Silica Polymerization Catalysts
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Solution Overview
Problem
The existing methods for activating chromium-supported catalysts for olefin polymerization are time-consuming and limited by the capacity of equipment, restricting the efficiency of polymer manufacturing processes.
Innovation Solution
A method involving alkaline aging of a silica support to reduce its surface area, followed by the addition of a chromium-containing compound and subsequent activation in batches of at least 226.8 kg within less than 8 hours, using equipment like fluidized beds for thermal treatment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional thermal treatment methods are used to activate chromium catalysts, then the catalyst achieves stable activity, but the activation process requires extended time periods and large expensive equipment
Solution Approach 1:
The silica support undergoes preliminary alkaline aging treatment before chromium deposition, which modifies the support structure in advance to reduce surface area and create optimal conditions for rapid catalyst activation. This preliminary modification enables the catalyst to achieve stable activity with significantly reduced activation time compared to conventional methods.
Solution Approach 2:
The invention changes the surface area parameter of the silica support through alkaline aging, reducing it to less than 50% of the original value. This parameter change in the support structure enables faster catalyst activation while maintaining stable catalytic activity, resolving the contradiction between activation time and activity stability.
2Productivity
If conventional catalyst activation methods are used, then equipment capacity limits production, but improving activation speed may compromise catalyst quality
Solution Approach 1:
The alkaline aging of silica support is performed in advance during catalyst preparation, creating a pre-optimized support structure that enables rapid activation. This preliminary action allows large batch sizes (at least 226.8 kg per batch) to be activated quickly without compromising catalyst quality, thereby increasing production capacity while maintaining reliability.
Solution Approach 2:
By changing the surface area parameter of the silica support through alkaline aging (reducing to less than 50% of original), the invention enables both fast activation and high catalyst activity. This parameter modification resolves the contradiction between productivity and reliability, allowing large-scale production without sacrificing catalyst performance.
3Ease of manufacture
If high surface area silica support is used, then catalyst preparation is easier, but activation time increases and production efficiency decreases
Solution Approach 1:
The invention deliberately changes the surface area parameter of the silica support by applying alkaline aging treatment, reducing it to less than 50% of the original value. This parameter change optimizes both the ease of chromium compound impregnation and the subsequent activation speed, resolving the contradiction between manufacturing ease and activation efficiency.
Solution Approach 2:
The alkaline aging treatment creates local structural modifications in the silica support, generating specific surface properties that facilitate both chromium compound uptake and rapid activation. This localized quality enhancement maintains ease of preparation while dramatically improving activation efficiency and production productivity.
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
This approach results in a rapidly activated catalyst composition that reduces activation time, increases efficiency, and enhances catalyst activity, allowing for higher production capacities and improved polymer properties.
Implementation Method 1
aging a silica support in an alkaline solution to produce an alkaline aged silica support
Implementation Method 2
activation of the silica support is carried out in batches of equal to or greater than 226.8 kg (500 lbs) for a time period of less than 8 hours
Data Source
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AI summary
A method of preparing a catalyst comprising aging a silica support in an alkaline solution to produce an alkaline aged silica support, removing at least a portion of the alkaline solution from the alkaline aged silica support to produce a dried silica support, and activating the silica support to produce a catalyst composition, wherein alkaline aging lowers the surface area of the silica support to less than about 50% of the original value and wherein activation of the silica support is carried out in batches of equal to or greater than about 500 lbs for a time period of less than about 8 hours. A method of preparing a polymer comprising alkaline aging a silica support material, adding chromium to the silica support material prior to the alkaline aging, after the alkaline aging, or both to form a chromium-silica support, rapidly activating the chromium-silica support produce an activated olefin polymerization catalyst, contacting the activated olefin polymerization catalyst with at least one monomer in a reaction zone under conditions suitable to produce a polymer, and recovering the polymer.