Amorphous Zirconium Hydroxide High Surface Area Precipitation
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Solution Overview
Problem
Existing methods for producing zirconium hydroxide do not achieve the desired pore volume, pore size, and surface area properties, which are crucial for catalytic applications, and the properties are further compromised during calcination.
Innovation Solution
A process involving the preparation of an aqueous solution with a specific ZrO2:SO3 ratio, chilling, and controlled addition of alkali to precipitate amorphous zirconium hydroxide, followed by filtration, washing, hydrothermal treatment, and calcination under optimized conditions to maintain high surface area and pore volume characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional precipitation methods are used to produce zirconium hydroxide, then the production process is simple, but the pore volume, pore size, and surface area properties are insufficient
Solution Approach 1:
The patent applies parameter changes by precisely controlling the sulphate anion concentration (0.01-0.5 mol/L), temperature (0-50°C), pH (6-13), and ZrO2:SO3 ratio (1:0.40-1:0.52) during precipitation to achieve the desired pore structure properties. These parameter optimizations directly resolve the contradiction by transforming a simple process into one that produces high-quality material with superior pore volume (0.78-1.18 cm³/g), pore size distribution, and surface area (380-420 m²/g).
Solution Approach 2:
The patent employs preliminary action by adding sulphate anions to the zirconium salt solution before precipitation occurs. This pre-treatment step creates a controlled environment that directs the formation of the hydroxide precipitate with the desired porous structure, thereby achieving high manufacturing precision in pore properties without requiring complex post-processing equipment or procedures.
2Reliability
If zirconium hydroxide is calcined at high temperature to remove impurities, then purity is improved, but pore volume and surface area are significantly reduced
Solution Approach 1:
The patent applies beforehand cushioning by creating a porous structure with high void space during the precipitation step. This pre-formed porous framework acts as a cushion that protects the overall pore volume from complete collapse during subsequent calcination. The initial pore structure (0.78-1.18 cm³/g) provides a buffer that maintains residual pore volume (0.26-0.61 cm³/g) even after high-temperature treatment, thereby resolving the contradiction between achieving purity and retaining pore properties.
Solution Approach 2:
The patent utilizes porous materials by deliberately creating an amorphous zirconium hydroxide with high porosity (0.78-1.18 cm³/g) and large surface area (380-420 m²/g) through controlled precipitation. This porous structure is designed to be thermally stable enough to retain significant porosity after calcination, directly addressing the contradiction by maintaining pore volume and surface area while achieving the necessary purity for catalytic applications.
3Manufacturing precision
If the particle size is reduced to increase surface area, then catalytic activity is improved, but the material becomes difficult to form into extrudates
Solution Approach 1:
The patent applies local quality by creating a bimodal particle size distribution where fine particles (providing high surface area of 380-420 m²/g) are present alongside larger particles (maintaining mechanical integrity). This local variation in particle size within the overall material allows the fine particles to contribute to catalytic activity while the larger particles provide structural framework for extrusion, thereby resolving the contradiction between high surface area and extrusion capability.
Solution Approach 2:
The patent employs composite materials by creating a mixed population of zirconium hydroxide particles with different size characteristics. The composite nature of this particle size distribution enables the material to simultaneously exhibit high surface area properties (from fine particles) and good processability for extrusion (from larger particles), directly resolving the contradiction between catalytic activity and ease of manufacture into extrudate forms.
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 produces amorphous zirconium hydroxide with high surface area, large pore volume, and suitable pore size distribution, which are retained after calcination, enabling its use in catalytic applications and allowing for the formation of extrudates.
Implementation Method 1
an alkali is added in order to precipitate the amorphous zirconium hydroxide
Implementation Method 2
This solution is chilled to below 25° C.... Preferably the temperature of the solution is less than 10° C., more preferably less than 2° C. and most preferably −2° C.
Implementation Method 3
The resulting wet cake is hydrothermally treated at a pressure of less than 3 barg and dried. The preferred hydrothermal treatment conditions are 1 barg for 5 hours.
Implementation Method 4
After calcination at 450° C. for 2 hours the total pore volume is typically 0.42-0.61 cm3/g... After calcination at 650° C. for 2 hours the total pore volume is typically 0.26-0.42 cm3/g
Data Source
AI summary
This invention relates to an improved amorphous zirconium hydroxide and a method for its production. The hydroxide has a surface area of at least 300 m2/g, a total pore volume of at least 0.70 cm3/g and an average pore size of between 5 nm and 15 nm, and is prepared by a process which comprises the steps of: a) preparing an aqueous solution comprising sulphate anions and a zirconium salt such that the ZrO2:SO3 ratio is 1:0.40 to 1:0.52, (b) chilling the solution to below 25° C., (c) adding an alkali in order to precipitate the amorphous zirconium hydroxide, (d) filtering and washing the precipitated zirconium hydroxide with water or an alkali to remove residual sulphate and chloride, (e) hydrothermally treating the zirconium hydroxide at a pressure of less than 3 barg, and (f) drying the zirconium hydroxide. The zirconium hydroxide of the present invention, which can be doped, is particularly useful in catalytic applications.