Ozone Catalyst Hybrid System for Nitrogen Oxide Removal
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Solution Overview
Problem
Current nitrogen oxide treatment methods, particularly those using gaseous ammonia as a reducing agent in SCR processes, face challenges such as high costs, catalyst degradation, and secondary pollution, with narrow temperature ranges and issues of ammonium salt formation and corrosion.
Innovation Solution
A method and apparatus utilizing an ozone and catalyst hybrid system, where moisture is removed from nitrogen oxide polluted air, ozone oxidizes NO to NO2, and residual ozone is decomposed into oxygen radicals to further oxidize NO2 to NO3-, allowing for complete nitrogen oxide removal at room temperature without secondary pollution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If SCR process uses gaseous ammonia as reducing agent with vanadium-based catalyst, then nitrogen oxide removal ratio reaches 90% or higher, but catalyst performance decreases due to wear, exchange, and toxicity
Solution Approach 1:
The invention extracts and eliminates the catalyst component from the nitrogen oxide removal process. Instead of using a vanadium-based catalyst that suffers from wear and toxicity issues, the patent employs ozone as a non-catalytic oxidizing agent that directly converts NO to NO2 without requiring any catalyst material, thereby solving the reliability problem while maintaining high removal efficiency
Solution Approach 2:
The invention replaces the expensive and toxic vanadium-based catalyst with ozone, which is a cheap, non-toxic, and easily manageable oxidizing agent. Ozone can be generated in-situ and decomposes into oxygen, leaving no harmful residues, thus eliminating the reliability issues associated with catalyst degradation and toxicity
2Productivity
If SCR process operates at temperature above 450° C., then nitrogen oxide conversion is efficient, but gaseous ammonia triggers oxidization to lower catalyst performance
Solution Approach 1:
The invention fundamentally changes the operating parameters by eliminating the temperature dependency associated with catalytic reactions. Instead of operating at high temperatures (150-450°C) required for catalyst activity, the ozone-based process operates effectively at room temperature or lower temperatures, avoiding the ammonia oxidization issue that occurs above 450°C while maintaining efficient NOx conversion
3Use of energy by stationary object
If SCR process operates at temperature below 150° C., then energy consumption is reduced, but gaseous ammonia reacts with moisture to form ammonium nitrate or ammonium sulfate
Solution Approach 1:
The invention extracts and eliminates the ammonia reducing agent from the process, replacing it with ozone as the active species. This eliminates the chemical reaction between ammonia and moisture that forms harmful ammonium salts at low temperatures, while still achieving effective nitrogen oxide removal through ozone oxidation
4Productivity
If wet method is used to remove nitrogen oxides, then both nitrogen oxides and sulfur oxides are removed, but high costs are incurred and N2O3 and N2O4 by-products are produced causing water pollution
Solution Approach 1:
The invention converts the harmful effect of ozone (potential secondary pollution) into a beneficial process by using controlled ozone dosing that completely oxidizes NO to NO2 and subsequently removes nitrogen oxides. The ozone is consumed in the reaction process and decomposes into oxygen, transforming a potential pollutant into a clean oxidation mechanism that eliminates by-product formation
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 approach achieves nearly complete nitrogen oxide removal with low operational costs and no secondary air pollution, effective across various nitrogen oxide concentrations from industrial to residential environments, using a simple and cost-efficient apparatus.
Implementation Method 1
contacting the moisture-removed nitrogen oxide polluted air with ozone to oxidize NO in the polluted air to NO2
Implementation Method 2
reacting residual ozone with a catalyst to generate oxygen radicals
Implementation Method 3
reacting the generated oxygen radicals with the nitrogen oxide polluted air from step 2) to oxidize NO2 in the polluted air to NO3-
Data Source
AI summary
The present invention is a method of treating nitrogen oxides using an ozone and catalyst hybrid system, as well as an apparatus, specifically relating to a method of treating nitrogen oxide using an ozone and catalyst hybrid system comprising: 1)removing moisture from the nitrogen oxide polluted air to be treated; 2) contacting the moisture-removed nitrogen oxide polluted air with ozone to oxidize NO in said polluted air to NO2; 3) reacting the residual ozone with a catalyst to generate oxygen radicals and then, reacting the oxygen radicals with the nitrogen oxide polluted air from step 2) to oxidize NO2 in the polluted air to NO3−. The nitrogen oxide treatment method and apparatus according to the present invention can effectively treat harmful nitrogen oxides, such as NO, NO2, using an ozone and catalyst hybrid system at room temperature without requiring a high temperature reaction or an ammonia gas as a reducing agent. In addition, the method and apparatus according to the present invention can be useful in the removal of nitrogen oxides in various areas because they can prevent secondary air pollution resulting from the use of ozone.