Core-Shell Catalyst for Ozone Oxidation
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Solution Overview
Problem
Current catalysts for ozonation in sewage treatment face challenges such as high production costs, poor catalytic performance, and environmental pollution due to metal ion contamination, with heterogeneous catalysts experiencing interphase diffusion resistance and high costs associated with using expensive active materials like La2O3, CuO, TiO2, MnO2, and CeO2.
Innovation Solution
A core-shell structured catalyst is developed, where a cheap hematite core is coated with a high-catalytic-activity shell made of ρ-type alumina and active ingredients like La2O3, CuO, TiO2, MnO2, or CeO2, using a spheronization molding process to maintain spherical morphology and mechanical strength, reducing production costs while ensuring effective catalytic performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If expensive catalyst materials like La2O3, CuO, TiO2, MnO2, and CeO2 are used to improve catalytic performance, then the catalytic activity is enhanced, but the production cost increases significantly
Solution Approach 1:
The patent applies local quality by concentrating the expensive active ingredients only in the shell layer (0.5-2 mm thick) rather than throughout the entire catalyst particle. The core (3-5 mm diameter) uses inexpensive materials like hematite, while the shell contains the costly catalytic components (La2O3, CuO, TiO2, MnO2, or CeO2) at 5-20 wt%. This localized distribution maintains high catalytic activity at the reaction interface while minimizing overall material costs.
Solution Approach 2:
The patent employs composite materials by combining inexpensive core materials (hematite, tourmaline, germanium, maifanite, or kaolin) with expensive shell materials (ρ-type alumina containing active ingredients). This composite structure leverages the mechanical strength and cost-effectiveness of the core while utilizing the high catalytic activity of the shell, achieving both economic and performance goals.
2Productivity
If homogeneous catalysts are used to achieve easy control and no interphase diffusion resistance, then the reaction efficiency is improved, but metal ion separation and recycling becomes difficult causing secondary pollution and increased operation costs
Solution Approach 1:
The patent uses the heterogeneous catalyst particle as an intermediary carrier that hosts the active catalytic components. The ρ-type alumina shell acts as a mediator that provides high catalytic activity similar to homogeneous catalysts while preventing metal ion dissolution into the aqueous phase. The core-shell structure allows ozone decomposition and hydroxyl radical generation without releasing harmful metal ions, thus eliminating secondary pollution while maintaining reaction efficiency.
3Object-generated harmful factors
If heterogeneous catalysts are used to avoid metal ion pollution and enable recycling, then environmental safety is improved, but interphase diffusion resistance and low contact rate between active sites and substrates reduce catalytic efficiency
Solution Approach 1:
The patent employs a thin shell structure (0.5-2 mm thick) made of ρ-type alumina that serves as a flexible interface between the bulk catalyst and the aqueous reaction medium. This thin shell minimizes the diffusion path length for ozone and organic substrates, reducing interphase diffusion resistance while maintaining the heterogeneous catalyst's advantage of preventing metal ion contamination. The shell thickness is optimized to balance diffusion efficiency with structural integrity.
Solution Approach 2:
The patent utilizes ρ-type alumina with controlled porosity in the shell layer to enhance mass transfer. The porous structure provides numerous channels for ozone and organic substrates to reach the active ingredients, increasing the contact rate between substrates and catalytic sites. This porous architecture maintains high catalytic efficiency while preserving the heterogeneous catalyst's environmental safety benefits.
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 core-shell catalyst achieves good catalytic performance, reduces production costs by utilizing inexpensive hematite, and minimizes environmental impact through stable alumina carriers, enhancing ozone utilization and reducing energy consumption in sewage treatment.
Implementation Method 1
The catalyst can decompose ozone catalytically, which is converted into hydroxyl radicals with strong oxidation performance
Implementation Method 2
The shell has a thickness of 0.5-1.5 mm... the shell is made of ρ-type alumina and an active ingredient
Data Source
AI summary
The invention discloses a core-shell structured catalyst comprising a core covered with a shell. The core is made of hematite, tourmaline, germanium, maifanite or kaolin. The invention also provides a method for preparing the catalyst including mixing raw materials of the core with water to form seed-balls with a particle size of 2-4 mm; mixing the seed-balls with raw materials of the shell and water, such that the seed-balls are covered with the raw materials of the shell to form pellets with a particle size of 3-5 mm; processing the pellets at 60-90° C. and then calcining to active the pellets at 450-550° C. to obtain a core-shell structured catalyst. The invention further discloses use of the core-shell structured catalyst in the ozone oxidation reaction. In the invention, a core-shell structured catalyst with good morphology and catalytic performance is prepared, and the production cost of the catalyst is reduced.