Layered Double Hydroxide Core-Shell Catalyst Supports
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Solution Overview
Problem
Existing catalyst supports for ethylene polymerization lack high polymerization activity per mol transition metal, molecular weight control, and regular free-flowing polymer particles, while also experiencing reduced porosity and surface area due to coating processes.
Innovation Solution
A catalyst system comprising a core@layered double hydroxide shell material with a solid, porous inorganic oxide-containing framework, where the LDH layer is grown on the surface of the framework to maintain high porosity and surface area, and is then thermally activated and treated with catalytic transition metal complexes for enhanced polymerization performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If LDH coating is applied to inorganic framework to create catalyst support, then catalytic activity and molecular weight control are improved, but porosity and surface area are reduced
Solution Approach 1:
The patent applies a thin film LDH coating on the inorganic framework surface. This thin film approach provides the necessary catalytic functionality while minimizing the coverage of pore openings, thereby preserving the porosity and surface area of the underlying framework structure.
Solution Approach 2:
The LDH coating is applied locally on the surface of the inorganic framework rather than as a thick uniform layer. This localized coating approach ensures that catalytic sites are provided where needed while leaving the bulk pore structure accessible, thus maintaining high surface area and porosity.
2Reliability
If LDH coating is applied to inorganic framework to create catalyst support, then catalytic activity and molecular weight control are improved, but porosity is reduced
Solution Approach 1:
The thin film LDH coating allows molecular weight control functionality to be provided without significantly blocking the pore structure. The thinness of the film ensures that diffusion pathways remain open, preserving the porosity needed for reactant and product transport.
Solution Approach 2:
The patent utilizes the porous inorganic framework as the core structure, maintaining its inherent porosity even after LDH coating. The framework's pore structure remains accessible, ensuring that molecular weight control is achieved without sacrificing the porosity required for efficient mass transfer.
3Ease of manufacture
If conventional coating process is used to deposit LDH on support, then catalyst support is formed, but porosity and surface area are significantly reduced
Solution Approach 1:
The patent employs a controlled coating process that deposits only a partial monolayer or thin multilayer of LDH on the framework surface. This partial coverage approach provides sufficient catalytic sites while leaving much of the framework surface area and pore structure exposed and accessible.
Solution Approach 2:
The inorganic framework is prepared in advance with optimized pore structure and surface properties before LDH deposition. This preliminary preparation ensures that the subsequent coating process deposits LDH in a controlled manner that minimizes pore blocking while maximizing catalytic activity.
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 achieves high polymerization activity, good molecular weight control, and regular free-flowing polymer particles with retained high surface area and porosity, outperforming current systems in ethylene polymerization.
Implementation Method 1
the LDH layer is grown on the surface of the framework to maintain high porosity and surface area
Implementation Method 2
is then thermally activated and treated with catalytic transition metal complexes for enhanced polymerization performance
Data Source
AI summary
A catalyst system comprises an activated sold support material and having, on its surface, one or more catalytic transition metal complex, wherein the solid support material comprises a core@layered double hydroxide shell material having the formula I TP @ {[Mz+(i -x)M'xy+(OH)2]a+(Xn )a/n»bH2O»c(AMO-solvent)}q (I) wherein T is a solid, porous, inorganic oxide-containing framework material, Mz+ and My+ are independently selected charged metal cations; Mz+ is a metal cation of charge z or a mixture of two or more metal cations each independently having the charge z; M'y+ is a metal cation of charge y or a mixture of two or more metal cations each independently having the charge y; z = 1 or 2; y = 3 or 4; 0 <x<0.9; b is 0 to 10; c is 0.01 to 10; P>0; q>0; Xn~ is an anion; with n > 0; a = z(1-x) + xy-2; and AMO-solvent is an organic solvent which is completely miscible with water. The catalyst system has use in the polymerisation and/or copolymerisation of at least one olefin for producing a homopolymer and/or copolymer. Also disclosed is a process for preparing a polyolefin homopolymer or a polyolefin copolymer which comprises reacting olefin monomers in the presence of the catalyst system. Preferably, the polyolefin is polyethylene and the olefin monomer is ethylene.