Nano-Al2O3 Hydroxyl Control via H2O2 Precipitation
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Solution Overview
Problem
Current methods for synthesizing nano-alumina catalyst carriers result in uncontrollable hydroxyl content, leading to variations in catalyst performance due to differences in active component dispersion, and existing methods for controlling hydroxyl content are complex and limited to high hydroxyl concentrations.
Innovation Solution
A method involving mixing a soluble aluminum salt and a pore-enlarging agent with a hydrogen peroxide solution, adjusting pH, precipitating, drying, and roasting to control hydroxyl content in nano-aluminum oxide, using hydrogen peroxide concentration to correlate with desired hydroxyl levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If hydrothermal synthesis is used to prepare nano-Al2O3, then the material can be obtained, but the yield is low and the hydroxyl content on the alumina surface is uncontrollable
Solution Approach 1:
The patent changes the preparation parameters by using wet chemical precipitation instead of hydrothermal synthesis, controlling pH value (8-9), temperature (20-80°C), and reaction time to achieve both high yield and controllable hydroxyl content. The alkaline solution concentration and addition rate are specifically controlled to regulate hydroxyl group formation on the alumina surface.
Solution Approach 2:
The patent replaces the hydrothermal synthesis method (which uses high temperature and pressure autoclave conditions) with a wet chemical precipitation method using simple mixing and filtration equipment, thereby improving both yield and controllability of hydroxyl content through easier parameter adjustment.
2Manufacturing precision
If conventional preparation methods are used, then nano-Al2O3 can be produced, but the hydroxyl content is uncontrollable leading to variable catalyst performance
Solution Approach 1:
The patent implements feedback control by monitoring and adjusting the pH value during precipitation (maintaining pH 8-9), and by controlling the alkaline solution addition rate to achieve desired hydroxyl content. This feedback mechanism ensures consistent catalyst performance by precisely controlling the anchoring sites for active components.
Solution Approach 2:
The patent systematically controls multiple parameters including pH value (8-9), temperature (20-80°C), reaction time (0.5-5 hours), and alkaline solution concentration to precisely regulate hydroxyl content, thereby ensuring reliable and consistent catalyst performance across different batches.
3Quantity of substance
If methods to increase hydroxyl content are used, then more anchoring sites are available for active components, but the synthesis method becomes complicated and is limited to high hydroxyl content only
Solution Approach 1:
The patent uses a simple wet chemical precipitation method with controllable parameters (pH, temperature, time, alkaline solution concentration) to achieve flexible control over hydroxyl content, ranging from low to high levels, without requiring complicated synthesis procedures. This allows optimization of hydroxyl content based on specific catalyst requirements.
Solution Approach 2:
The patent develops a universal preparation method that can produce nano-Al2O3 with different hydroxyl content levels (low, medium, high) using the same basic procedure, making it adaptable to various catalyst applications rather than being limited to a single hydroxyl content range.
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
Enables the production of nano-aluminum oxide with controllable hydroxyl content, facilitating uniform dispersion of active components as single atoms or clusters, enhancing catalytic performance by regulating anchoring sites.
Implementation Method 1
H2O2 dissolved in water dissociates a large number of hydroxyl radicals
Implementation Method 2
mixing a soluble aluminum salt and a pore-enlarging agent with a H2O2 solution, adjusting a pH value of a resulting mixture to 8 to 9 with an alkaline solution, and conducting precipitation to obtain a precipitate
Implementation Method 3
conducting roasting on the aluminum hydroxide precursor to obtain the nano-Al2O3
Implementation Method 4
mixing a soluble aluminum salt and a pore-enlarging agent with a H2O2 solution
Implementation Method 5
conducting ultrasonic cleaning on a roasted product at 100 kHz to 200 kHz for 10 min to 2 h
Data Source
AI summary
The present disclosure provides a preparation method of nano-aluminum oxide (nano-Al2O3) with a controllable hydroxyl content, belonging to the technical field of nano-alumina. H2O2 dissolved in water dissociates a large number of hydroxyl radicals. In the present disclosure, a resulting H2O2 solution is used as a solvent for precipitation; during the precipitation, a soluble aluminum salt and a pore-enlarging agent are reacted to generate a precipitate under alkaline conditions, and the hydroxyl radicals are distributed on a surface of the precipitate. During drying, the hydroxyl radicals are converted into bound water and distributed on a surface and in pores of an aluminum hydroxide precursor; during roasting, the bound water is destroyed to form hydroxyl. The hydroxyl content of the nano-Al2O3 can be regulated by controlling a concentration of the H2O2 solution, and the nano-Al2O3 has the hydroxyl content positively correlated with the concentration of the H2O2 solution.