Monolithic Catalyst for NOx and Carbon Removal
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Solution Overview
Problem
Current catalysts for NOx removal in power plants are inefficient due to blockage by ammonium sulphate and soot, require expensive ammonia, and are not durable, while existing methods for direct NO decomposition are not scalable for industrial use.
Innovation Solution
A monolithic catalyst with a spinel oxide phase on an acid-proof steel structure, formed by alternately laying sinusoidally corrugated and smooth steel foil bands, which are folded and oxidized to create a thin, active oxide layer for simultaneous NOx and carbon particle decomposition at low temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ceramic monoliths are used as catalyst carriers, then catalyst placement is possible, but the carriers are fragile and have thick walls
Solution Approach 1:
The patent changes the material parameter of the catalyst carrier from ceramic to metallic foil, fundamentally altering the mechanical properties. The metallic foil provides flexibility, durability, and thin wall structure while maintaining catalytic functionality through oxide layer formation on the metal surface.
Solution Approach 2:
The patent creates a composite structure where a metallic foil substrate serves as the mechanical support and an oxide layer forms the catalytic active phase. This composite approach combines the mechanical strength and flexibility of metal with the catalytic properties of oxide materials.
2Productivity
If conventional catalysts with divanadium pentoxide and tungsten/molybdenum trioxides are used, then catalytic activity is improved, but the catalysts are blocked by ammonium sulphate and soot particles
Solution Approach 1:
The patent changes the chemical composition parameters by eliminating tungsten/molybdenum trioxides and divanadium pentoxide, instead using a metallic foil with controlled oxide layer. This compositional change prevents the formation of ammonium sulphate deposits while maintaining catalytic activity through the metal-oxide interface.
Solution Approach 2:
The patent converts the potential harm of metal oxidation into a benefit by forming a controlled oxide layer on the metallic foil surface. This oxide layer serves as the active catalytic phase, transforming what would normally be a degradation mechanism into a functional feature that prevents blockage while enabling catalysis.
3Productivity
If ammonia is used as a reducer for NOx removal, then NOx decomposition is achieved, but the process becomes expensive and ammonia contaminates the air
Solution Approach 1:
The patent extracts and eliminates the ammonia reducer from the system, replacing it with a catalyst that enables direct thermal decomposition of NOx. This removes the source of ammonia contamination and eliminates the need for expensive ammonia dispensing infrastructure while maintaining effective NOx removal.
Solution Approach 2:
The patent enables the system to use its own thermal energy and the natural decomposition tendency of NOx at elevated temperatures to drive the removal process. The catalyst facilitates this self-service decomposition without requiring external chemical reducers like ammonia.
4Ease of manufacture
If the oxide catalyst surface is maintained in a highly reduced state, then NO decomposition is easier, but additional reducers are needed which increase complexity
Solution Approach 1:
The patent removes the need for additional reducers and complex dispensing systems by using a metallic foil-based catalyst that maintains appropriate surface reduction states through its inherent metal-oxide equilibrium. The system leverages the natural redox properties of the metal foil without requiring external reducing agents.
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 catalyst achieves high activity and selectivity in NOx decomposition and carbon oxidation at 300-350°C, maintaining stability and reducing the need for additional reducers, with a durable and cost-effective design.
Implementation Method 1
The basis of this technology is the reduction of nitric oxide with ammonia on catalysts on the basis of divanadium pentaoxide placed on the anatase form of TiO2
Implementation Method 2
the easier the dissociation of NO particle adsorbed on the surface oxide cation
Implementation Method 3
reaction of particles with atomic forms of oxygen forming on the oxide surface
Implementation Method 4
the operating temperature of the catalyst is high enough to maintain the oxygen pressure in the gas phase lower than the equilibrium pressure of oxygen over oxide
Data Source
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AI summary
A monolithic catalyst for simultaneous removal of NOx and carbon particles, especially from off-gases of carbon power plants contains the monolith is made from acid-proof austenitic steel. The catalyst is a two- phase one; moreover, it contains the phases NiFe2O4 and Fe2O3(Mh) with spinel structure, and these phases form microcrystallites, additionally containing Mn. The manner of production of the monolithic catalyst for simultaneous removal of NOx and carbon particles, especially from off-gases of carbon power plants depends on the monolith is subject to oxidation after which the resulting oxide layers are washed with the solution of nickel salts; later the monolith is baked in the oxidising atmosphere with the view to inserting nickel ions into the oxide layer; finally this obtained oxide layers are subject to reduction.