Hydrated TiO2-SiO2 Catalyst for Thermal Stability
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Solution Overview
Problem
Existing titanium dioxide-based photocatalysts and TiO2/SiO2 materials face challenges with thermal stability and catalytic activity, particularly at elevated temperatures, due to reduced specific surface areas and coverage of the catalytically active titanium dioxide surface by SiO2, which diminishes their photocatalytic properties.
Innovation Solution
A powdered catalyst material with a high TiO2/SiO2 weight ratio of at least 3 and less than 30, comprising hydrated titanium oxide and silicon dioxide, processed to maintain a specific surface area greater than 300 m2/g and an isoelectric point between 4.0 and 7.0, ensuring excellent thermal stability and catalytic activity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If SiO2 is added to TiO2 to increase thermal stability, then thermal stability is improved, but the catalytically active titanium dioxide surface is covered with SiO2, which limits catalytic properties
Solution Approach 1:
The patent applies parameter changes by carefully controlling the SiO2 content to maintain a TiO2/SiO2 weight ratio of at least 3:1, ensuring that SiO2 provides thermal stability while TiO2 maintains sufficient surface area for catalytic activity. This optimal compositional parameter resolves the contradiction between thermal stability and catalytic activity.
Solution Approach 2:
The patent creates a composite material system where TiO2 and SiO2 work synergistically. The composite structure allows SiO2 to provide thermal stability framework while TiO2 domains maintain catalytic functionality, achieving both thermal stability and catalytic activity through proper material composition and interaction.
2Stability of the object's composition
If thermal treatments such as hydrothermal treatments and/or calcination are applied to increase crystallinity, then crystallinity is improved, but the specific surface area of the hydroxy group content is reduced, which is unfavorable for catalytic applications
Solution Approach 1:
The patent optimizes thermal treatment parameters by limiting calcination temperature to below 500°C and controlling treatment duration, thereby achieving sufficient crystallinity for stability while preserving high specific surface area (>300 m2/g) necessary for catalytic activity. This parameter optimization resolves the contradiction between crystallinity and surface area.
3Reliability
If pure titanium dioxide is used as a support material, then catalytic activity is maintained, but thermal stability is not good enough for hydrotreating applications at 400°C, which results in ageing effects and loss of catalytic activity
Solution Approach 1:
The patent creates a TiO2-SiO2 composite where SiO2 provides the thermal stability framework necessary for high-temperature hydrotreating applications, while TiO2 maintains catalytic activity. The composite structure prevents the ageing effects that occur in pure TiO2 at 400°C, resolving the contradiction between catalytic activity and thermal stability.
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 material achieves enhanced catalytic properties and thermal stability, maintaining high photocatalytic activity even at elevated temperatures, surpassing the limitations of prior art by preserving a sufficient surface area and catalytic activity.
Implementation Method 1
a process for preparing a catalyst material on a titanium oxide basis in powder form, in which an aqueous suspension of titanium oxide hydrate particles and/or hydrated titanium oxide is treated with a Si-containing solution, in particular a water glass solution, in which SiO2 is precipitated onto the surface of the titanium oxide particles
Implementation Method 2
the powdered, inorganically post-processed titanium oxide has a combined content of at least 90 wt.-% of a hydrated titanium oxide and silicon dioxide, wherein the TiO2/SiO2 weight ratio is at least 3 and less than 30, wherein the remainder to 100 wt.-% is made up of bound water and traces of by-elements
Data Source
AI summary
A powdered catalyst material on a titanium oxide basis. The powdered catalyst material includes a combined content of at least 90 wt.-% of a hydrated titanium oxide having the general formula TiO(2-x)(OH)2x, with 0<x≤1, (calculated as TiO2), and a silicon dioxide and hydrated precursors of the silicon dioxide (calculated as SiO2). A weight ratio of TiO2/SiO2, determined for TiO2 and SiO2 respectively, is at least 3 and less than 30. The wt.-% is based on a total weight of the catalyst material after the catalyst material has been dried at 105° C. for at least 2 hours. The powdered catalyst material has a specific surface area of >300 m2/g and an isoelectric point of from 4.0 to 7.0.