Chromium Oxide Particle Synthesis via Porous Carbon Template
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Solution Overview
Problem
Current methods for producing chromium oxide particles and composite particles of iron oxide-chromium alloy are complex and difficult to achieve uniform particle sizes of several tens of nanometers, often requiring environmentally hazardous reagents and vulnerable support materials like silica, which are not suitable for high-temperature reactions due to sintering issues.
Innovation Solution
A method using porous carbon material as a sacrificial template for melt-infiltration of chromium and iron hydrate salts, followed by high-temperature calcination to form particle size-controlled chromium oxide and composite particles, ensuring uniform sizes of 10-50 nanometers without sintering, and removing the carbon template by pyrolysis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional methods are used to produce chromium oxide particles, then the synthesis can be achieved, but the process becomes complex and requires environmentally hazardous reagents
Solution Approach 1:
The patent uses porous silica particles as an intermediary template to guide the formation of chromium oxide particles. The silica template meditates the synthesis process by providing a structured framework that controls particle morphology and size, eliminating the need for complex conventional synthesis methods and hazardous reagents. After infiltration of chromium-containing solution and drying, the silica template is removed by calcination, leaving behind chromium oxide particles with controlled structures.
2Manufacturing precision
If conventional methods are used to produce chromium oxide particles, then the synthesis can be achieved, but obtaining small uniform products at nano level is difficult
Solution Approach 1:
The patent employs porous silica particles with controlled pore sizes as templates. The pore structure of the silica material directly determines the size and uniformity of the resulting chromium oxide particles. By selecting silica with specific pore diameter ranges (e.g., 2-50 nm), the method achieves precise control over nanoparticle size distribution, making nanoscale particle production straightforward and uniform.
3Stability of the object's composition
If silica is used as a support for nanoparticles, then sintering resistance is improved, but the support becomes vulnerable to steam
Solution Approach 1:
The patent creates composite particles consisting of chromium oxide nanoparticles supported on or within a silica matrix. The composite structure combines the high thermal stability of chromium oxide with the structural support of silica, achieving resistance to sintering at high temperatures. The chromium oxide component maintains catalytic activity while the silica framework provides mechanical stability and steam resistance, overcoming the limitations of using either material alone.
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 allows for the production of chromium oxide and composite particles with high thermal stability and uniform sizes, enhancing their performance as catalysts in high-temperature reactions like the reverse water gas shift, with improved catalytic efficiency and stability.
Implementation Method 1
mixing a chromium hydrate salt, an iron hydrate salt, and the porous carbon material particles; melt-infiltrating the chromium hydrate salt and the iron hydrate salt into pores of the porous carbon material particles
Implementation Method 2
calcining the chromium hydrate salt, the iron hydrate salt, and the porous carbon material particles at a high temperature of 700 to 900° C. to form chromium oxide particles... and removing the porous carbon material by pyrolysis
Implementation Method 3
calcining the chromium hydrate salt, the iron hydrate salt, and the porous carbon material particles at a high temperature of 700 to 900° C. to form chromium oxide particles, of which particle size is controlled by the pores of the porous carbon material
Data Source
AI summary
Provided are particle size-controlled, chromium oxide particles or composite particles of iron oxide-chromium alloy and chromium oxide; a preparation method thereof; and use thereof, in which the chromium oxide particles or the composite particles of iron oxide-chromium alloy and chromium oxide having a desired particle size are prepared in a simpler and more efficient manner by using porous carbon material particles having a large pore volume as a sacrificial template. When the chromium oxide particles or the composite particles of iron oxide-chromium alloy and chromium oxide thus obtained are applied to gas-phase and liquid-phase catalytic reactions, they are advantageous in terms of diffusion of reactants due to particle uniformity, high-temperature stability may be obtained, and excellent reaction results may be obtained under severe reaction environment.