Mixed Oxide Catalysts for VOC Oxidation and NOx Reduction
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Solution Overview
Problem
Existing mixed oxides catalysts for the oxidation of organic compounds, decomposition of nitrogen protoxide, and combustion of CO, H2, and CH4 off gases from fuel cells lack high thermal stability and require labor-intensive, multi-step impregnation processes during industrial preparation.
Innovation Solution
Development of mixed oxides comprising manganese, copper, and rare earth metals with specific compositions (MnO, CuO, and La2O3/Nd2O3) that exhibit high thermal stability and activity, prepared using a simplified one-step impregnation process after lanthanum nitrate solution impregnation, with the rare earth metals capable of multivalence states, supported on inorganic carriers like alumina or silica.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If multi-step impregnation process is used for catalyst preparation, then catalyst composition can be controlled, but manufacturing complexity and labor intensity increase
Solution Approach 1:
The patent combines multiple impregnation steps into a single step by simultaneously impregnating the carrier with solutions containing lanthanum nitrate, copper nitrate, and manganese nitrate. This merging of steps reduces labor intensity and process complexity while maintaining the ability to control catalyst composition through adjusted solution concentrations and impregnation conditions.
Solution Approach 2:
The single impregnation solution serves multiple functions: it provides lanthanum for thermal stability, copper for catalytic activity, and manganese for oxidation performance. This multi-functional approach eliminates the need for separate impregnation steps for each metal component.
2Productivity
If conventional mixed oxide catalysts are used, then oxidation activity is achieved, but thermal stability is insufficient above 700°C
Solution Approach 1:
The patent creates a composite catalyst material combining lanthanum oxide, copper oxide, and manganese oxide in specific ratios (La2O3: 30-70 wt%, CuO: 10-40 wt%, MnO: 10-40 wt%). This composite structure leverages the thermal stability of lanthanum oxide to maintain catalyst integrity above 700°C while preserving the oxidation activity contributed by copper and manganese components.
3Stability of the object's composition
If perovskite type catalysts are used, then thermal stability up to 650°C is achieved, but composition control flexibility is limited
Solution Approach 1:
The patent employs parameter changes by allowing flexible adjustment of the oxide composition ratios within broad ranges (La2O3: 30-70 wt%, CuO: 10-40 wt%, MnO: 10-40 wt%). This flexibility enables optimization for different application conditions while maintaining thermal stability, unlike fixed perovskite stoichiometries.
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 catalysts demonstrate enhanced activity and longer lifetime at high temperatures, improved thermal stability, and simplified industrial-scale preparation, achieving complete oxidation of VOCs, efficient decomposition of nitrogen protoxide, and effective combustion of fuel cell off-gases with reduced NOx generation at lower temperatures.
Implementation Method 1
Mixed oxides catalysts comprising oxides of manganese, copper and rare earth metals, usable in particular for the full oxidation of organic compounds (VOC) to CO2 and H2O
Implementation Method 2
the conversion of nitrogen protoxide to nitrogen and oxygen
Implementation Method 3
the combustion of CO, H2 and CH4 off gases from the anode of fuel cells
Implementation Method 4
full oxidation of organic compounds (VOC) to CO2 and H2O
Data Source
AI summary
Mixed oxides catalysts usable in particular in the full oxidation to CO2 and H2O of volatile organic compounds (VOC), in the decomposition of nitrogen protoxide to nitrogen and oxygen and the combustion of CO, H2 and CH4 off gases in fuel cells, comprising oxides of manganese, copper and La2O3 and/or Nd2O3, having a percentage composition by weight expressed as MnO, CuO, La2O3 and/or Nd2O3 respectively of 35-56%, 19-31% and 20-37%. The oxides are supported on inert porous inorganic oxides, preferably alumina.