Porous Monolith Multimodal Porosity Preparation
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Solution Overview
Problem
Existing methods for preparing porous monoliths with inorganic semiconductors lack fine control over porosity and require reactive precursors, leading to high production costs and limited variability in semiconductor materials.
Innovation Solution
A process using polymer particles as pore-forming agents and oxide semiconductor precursors in powder form, involving a heat treatment under controlled conditions to achieve multimodal porosity, allowing for precise control of porosity and reduced production costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If reactive precursors (alkoxides) are used to prepare porous monoliths, then the monolith can be formed, but production cost increases and variability in semiconductor materials is limited
Solution Approach 1:
The patent replaces expensive, reactive alkoxide precursors with inexpensive, stable oxide semiconductor powders. These stable powders can be stored and handled without special conditions, eliminating the need for controlled hydrolysis reactions and reducing production costs while enabling greater material variability.
Solution Approach 2:
The patent changes the physical and chemical parameters of the precursor material from reactive alkoxides to stable oxide powders. This parameter change allows for easier handling, lower cost, and greater flexibility in selecting different semiconductor materials without being constrained by reactivity issues.
2Manufacturing precision
If conventional emulsion processes are used, then macroporosity can be obtained, but fine control of porosity is not achieved
Solution Approach 1:
The patent uses pre-formed polymer particles with controlled sizes as pore-forming agents. These particles are prepared in advance with specific size distributions, and when incorporated into the monolith, they create corresponding porous structures after removal. This preliminary preparation enables precise control over the final porosity without complex process adjustments.
Solution Approach 2:
The patent employs polymer particles as sacrificial pore-forming agents that create controlled porous structures in the final monolith. By selecting particles with specific size distributions and controlling their incorporation, the method achieves fine control over porosity characteristics while simplifying the overall process.
3Productivity
If film thickness is reduced to improve photocatalytic effectiveness, then photocatalytic performance increases, but mechanical strength and handling become problematic
Solution Approach 1:
The patent creates a monolith structure with controlled porosity that provides mechanical strength while maintaining thin effective photocatalytic pathways. The porous architecture allows light penetration and reactant access throughout the bulk material, achieving high photocatalytic effectiveness without requiring extremely thin films that would be mechanically weak.
Solution Approach 2:
The patent combines oxide semiconductor particles with a refractory oxide matrix to create a composite monolith structure. This composite provides both the mechanical strength needed for handling and the porous architecture necessary for high photocatalytic effectiveness, reconciling the contradiction between thickness and strength.
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 process enables the production of monoliths with controlled multimodal porosity, enhancing their suitability for photocatalytic applications such as hydrogen production by dissociation of water, with improved performance and cost-effectiveness.
Implementation Method 1
d) a heat treatment of the paste obtained in step c) is carried out in order to obtain the monolith with multimodal porosity
Implementation Method 2
a heat treatment of the paste obtained in step c) is carried out in order to obtain the monolith with multimodal porosity, said heat treatment carried out under air at a temperature of between 300 and 1000° C. for 1 to 72 h
Data Source
AI summary
Process for preparing a porous monolith comprising between 10% and 100% by weight of a semiconductor relative to the total weight of the porous monolith, which process comprises the following steps:a) a first aqueous suspension containing polymer particles is prepared;b) a second aqueous suspension containing particles of least one inorganic semiconductor is prepared;c) the two aqueous suspensions prepared in steps a) and b) are mixed in order to obtain a paste;d) a heat treatment of the paste obtained in step c) is carried out in order to obtain the monolith with multimodal porosity.