Water-Insoluble Metal Hydroxide Combustion Synthesis
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Solution Overview
Problem
Conventional methods for preparing water-insoluble metal hydroxides and oxides often result in low crystallinity, instability, and difficulty in uniformly incorporating alkali metal components, limiting their utility in applications such as fluorescent materials and catalysts.
Innovation Solution
A method involving the combustion synthesis of a mixed aqueous solution containing a metal salt and an alkali salt, followed by high-temperature heat treatment and washing to produce a water-insoluble metal hydroxide with high crystallinity and chemically stable alkali metal components, which can be further converted into metal oxides.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If liquid-phase methods (hydrothermal synthesis or precipitation) are used to produce water-insoluble metal hydrates, then the production process is simple, but the resulting metal hydrates have low crystallinity and are unstable
Solution Approach 1:
The invention changes the fundamental parameter of the synthesis approach from liquid-phase to combustion synthesis. By using combustion synthesis with controlled temperature parameters (400-700°C for combustion, 700-1400°C for heat treatment) and specific atmosphere conditions, the method achieves high crystallinity and stability while maintaining operational simplicity through a single-step combustion process followed by heat treatment.
2Ease of manufacture
If conventional preparation methods are used, then the process is straightforward, but it is difficult to uniformly incorporate alkali metal components into the metal hydrate
Solution Approach 1:
The invention merges the incorporation of alkali metal components into the combustion synthesis process itself. By adding alkali metal salts to the combustion mixture, the alkali metals are uniformly distributed throughout the metal hydrate structure during the combustion reaction, achieving homogeneous incorporation without requiring separate doping steps or complex multi-stage processes.
3Reliability
If electrochemical methods are used to prepare metal hydroxide nanoplatelets, then the product quality is good, but the method requires complicated steps and is not economically efficient
Solution Approach 1:
The invention replaces the electrochemical method (which requires electrolyzers, electrical power sources, and complex cell assemblies) with a combustion synthesis method. This substitution eliminates the need for complex electrochemical equipment and multiple processing steps, achieving comparable or superior product quality through a simpler thermal chemistry approach that is more economically efficient for large-scale production.
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 method efficiently produces water-insoluble metal hydroxides with high crystallinity and phase purity, suitable for various applications including fluorescent materials and catalysts, with improved sintering capabilities and unique light-emitting properties.
Implementation Method 1
combusting a mixed aqueous solution of a metal salt, an alkali salt and an urea at a temperature of from 400° C. or more to less than 700° C.
Implementation Method 2
subjecting a powder obtained in step (a) to heat treatment at a temperature of 700° C. to 1,300° C.
Implementation Method 3
washing a powder obtained in step (b) with an aqueous solution
Data Source
AI summary
The present invention relates to a novel method for preparing a water-insoluble metal hydroxide, and a use thereof. The water-insoluble metal hydroxide of the present invention is conveniently and efficiently prepared s through the high-temperature heat treatment step two times and the washing step, and thus contains a small amount of an alkali metal and has a high crystallinity and a phase purity. The water-insoluble metal hydroxide of the present invention or metal oxide therefrom exhibits an absorption wavelength at a low wavelength range (for example, 490 nm or less) and a light emitting wavelength at a high wavelength range (for example, from 500 nm or more to less than 1,100 nm). Accordingly, the water-insoluble metal hydroxide of the present invention may be efficiently used in various applications such as a fire retardant, an antacid, an adsorbent and so forth, and may also be doped with another metal ion to be utilized as a raw material for fabricating a catalyst, a fluorescent material, an electrode material, a secondary battery material and the like.