Three-Coat Catalyst for NOx Reduction and N2O Minimization
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing catalysts for NOx oxidation and selective catalytic reduction (SCR) in exhaust gases suffer from high nitrous oxide (N2O) formation due to unselective oxidation of ammonia and NOx, which is not optimized for NO2 production and results in reduced catalytic activity.
Innovation Solution
A catalyst with three coatings on a flow-through substrate: a first coating of vanadium oxide and zeolitic material with copper and iron, a second coating of platinum group metals on a non-zeolitic oxidic material, and a third coating of platinum group metals on an oxidic material, optimized in terms of coverage and composition to enhance NH3 oxidation, NO oxidation, and NOx conversion while minimizing N2O formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a catalyst combines SCR and oxidation functionality in mixed zones, then the device complexity is reduced, but the nitrous oxide (N2O) formation increases due to unselective DeNOx and unselective oxidation of NH3
Solution Approach 1:
The catalyst is divided into three distinct coatings applied in sequence on the substrate: a first coating with vanadium oxide and zeolitic material for SCR, a second coating with platinum group metals on non-zeolitic oxidic material for selective oxidation, and a third coating with platinum group metals on oxidic material for additional oxidation functionality. This segmentation allows each coating to perform its specific function without the harmful interactions that occur in mixed zones.
Solution Approach 2:
Different regions of the catalyst have different compositions and functions. The first coating region provides SCR activity, the second coating region provides selective oxidation with low N2O formation, and the third coating region provides additional oxidation activity. This local differentiation of properties enables the catalyst to achieve high catalytic activity while minimizing N2O formation.
2Productivity
If a diesel oxidation catalyst or three-way conversion catalyst is used for NOx treatment, then the oxidation activity is improved, but the nitrous oxide (N2O) selectivity increases due to unselective oxidation of NH3
Solution Approach 1:
The catalyst uses specific platinum group metal compositions and support materials (non-zeolitic oxidic materials) in the second coating to modify the oxidation selectivity parameters. This parameter optimization ensures that ammonia oxidation proceeds selectively to nitrogen and water rather than producing nitrous oxide, while maintaining high oxidation activity for NOx conversion.
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 catalytic activity for NH3 oxidation, NO oxidation, and NOx conversion while significantly reducing N2O formation, thereby improving the efficiency of NOx treatment in exhaust gases.
Implementation Method 1
a catalyst for the oxidation of NO, for the oxidation of ammonia and for the selective catalytic reduction of NOx
Implementation Method 2
a catalyst for the oxidation of NO, for the oxidation of ammonia and for the selective catalytic reduction of NOx
Implementation Method 3
a catalyst for the oxidation of NO, for the oxidation of ammonia and for the selective catalytic reduction of NOx
Data Source
AI summary
The present disclosure relates to a catalyst for the oxidation of NO, for the oxidation of ammonia and for the selective catalytic reduction of NOx, the catalyst comprising a flow-through substrate, a first coating comprising one or more of a vanadium oxide and a zeolitic material comprising one or more of copper and iron, a second coating comprising a platinum group metal component supported on a non-zeolitic oxidic material and further comprising one or more of a vanadium oxide and a zeolitic material comprising one or more of copper and iron and a third coating comprising a platinum group metal component supported on an oxidic material. The present disclosure further relates to an exhaust gas treatment system comprising said catalyst.