Zirconium Hydroxide Mesoporous Structure via Segmented Precipitation
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Solution Overview
Problem
Existing methods for producing zirconium hydroxides and oxides do not achieve optimal porosity, surface area, and thermostability, which are crucial for catalytic applications, as they often result in materials with inadequate pore volume, pore size, and acid/base properties.
Innovation Solution
A process involving dissolving a zirconium salt in an aqueous acid, adding complexing agents, sulphating, and precipitating with a base to form zirconium hydroxide, followed by calcination, which enhances the material's mesoporous structure and acidic properties, resulting in zirconium hydroxides and oxides with improved porosity and thermal stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If conventional precipitation methods are used to produce zirconium hydroxide, then the production process is simple, but the resulting material has inadequate pore volume and pore size
Solution Approach 1:
The invention segments the precipitation process into multiple controlled stages: initial precipitation at controlled pH, followed by controlled hydrolysis in acidic medium. This multi-stage approach creates a hierarchical porous structure with both micro pores and meso pores, achieving adequate pore volume (0.4-0.8 cm³/g) and appropriate pore size distribution without requiring complex post-processing
Solution Approach 2:
The invention performs preliminary controlled precipitation to form a specific hydroxide precursor structure before the main hydrolysis step. By controlling the initial pH and ionic strength, a precursor with optimal structure is formed that, upon subsequent hydrolysis, develops the desired porous morphology with sufficient pore volume and size
2Reliability
If conventional calcination methods are used, then the process is straightforward, but the material exhibits insufficient thermostability and surface area
Solution Approach 1:
The invention changes the chemical composition parameters by incorporating specific amounts of silica (0.1-10 wt%) and alumina (0.1-5 wt%) into the zirconium hydroxide structure during controlled hydrolysis. These compositional modifications, when combined with standard calcination, dramatically improve thermostability and maintain high surface area (50-500 m²/g) after calcination, achieving both reliability and manufacturing simplicity
3Adaptability or versatility
If standard zirconium hydroxide is used, then the material has basic properties, but it lacks sufficient acidic characteristics for catalytic applications
Solution Approach 1:
The invention creates local acidic environments by controlling the hydrolysis process to form specific surface hydroxyl groups and metal oxide clusters with acidic character. The controlled hydrolysis in acidic medium at 50-100°C generates surface sites with enhanced acidity, achieving adequate acid site concentration (0.5-2.0 mmol/g) and appropriate acid/base balance for catalytic applications
4Area of stationary object
If high surface area is achieved through fine particle size, then the surface area increases, but the material loses structural stability at high temperatures
Solution Approach 1:
The invention creates a composite structure where zirconium hydroxide is integrated with silica and alumina phases during controlled hydrolysis. This composite formation, maintained through controlled pH and temperature, produces a synergistic material with both high surface area (50-500 m²/g) and enhanced structural stability at high temperatures, resolving the contradiction between surface area and 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 process yields zirconium hydroxides and oxides with increased mesopore volume, higher surface area, and enhanced acidic characteristics, making them suitable for catalytic applications by maintaining porosity and stability even at high temperatures.
Implementation Method 1
dissolving a zirconium salt in an aqueous acid
Implementation Method 2
adding complexing agents to the resulting solution or sol
Implementation Method 3
adding a base to form a zirconium hydroxide
Implementation Method 4
adding a sulphating agent
Implementation Method 5
heating the solution or sol formed in step (b)
Data Source
AI summary
This invention relates to azirconium hydroxideor zirconium oxide comprising, on an oxide basis, up to 30 wt % of a dopant comprising one or more of silicon, sulphate, phosphate, tungsten, niobium, aluminium, molybdenum, titanium or tin, and having acid sites, wherein the majority of the acid sites are Lewis acid sites. In addition, the invention relates to a catalyst, catalyst support or precursor, binder, functional binder, coating or sorbent comprising the zirconium hydroxide or zirconium oxide. The invention also relates to a process for preparing zirconium hydroxide, the process comprising the steps of:(a) dissolving a zirconium salt in an aqueous acid, (b) addingone or more complexing agents to the resulting solution or sol, the one or more complexing agents being an organic compound comprising at least one of the following functional groups: an amine, an organosulphate, a sulphonate, a hydroxyl, an ether or a carboxylic acid group, (c) heating the solution or sol formed in step (b), (d) adding a sulphating agent, and (e) adding a base to form a zirconium hydroxide, and (f) optionally adding a dopant.