Doped TiO2 AMOx Catalyst for Low N2O Exhaust Treatment
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing selective ammonia oxidation (AMOx) catalysts face a trade-off between ammonia oxidation activity and nitrogen selectivity, with most catalysts producing significant amounts of nitrous oxide (N2O) as a byproduct, and pure titania is not considered suitable due to poor hydrothermal stability.
Innovation Solution
A platinum group metal (PGM) supported on TiO2 doped with up to 10% wt of SiO2, WO3, ZrO2, Y2O3, or La2O3 is used to create an AMOx catalyst with high ammonia oxidation activity and high nitrogen selectivity, minimizing N2O formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional AMOx catalysts are used to achieve high ammonia oxidation activity, then NH3 conversion is improved, but N2O formation increases and selectivity to N2 decreases
Solution Approach 1:
The patent changes the chemical composition parameters of the catalyst by doping TiO2 with specific metal oxides (V2O5, Nb2O5, Ta2O5, MoO3, or WO3) at controlled concentrations (0.1-10 wt%). This parameter modification transforms the catalytic properties to achieve both high ammonia oxidation activity and high N2 selectivity, resolving the trade-off between productivity and harmful byproduct formation.
Solution Approach 2:
The patent creates composite catalyst materials by combining TiO2 support with doped metal oxides and PGMs. This composite structure synergistically combines the high surface area and stability of TiO2 with the catalytic activity of metal oxides and PGMs, achieving both high ammonia oxidation activity and high N2 selectivity while minimizing N2O formation.
2Area of stationary object
If pure TiO2 is used as support to achieve high surface area, then catalytic activity is improved, but hydrothermal stability deteriorates due to significant surface area reduction after aging
Solution Approach 1:
The patent creates composite material systems by doping TiO2 with stable metal oxides (V2O5, Nb2O5, Ta2O5, MoO3, or WO3). These dopants form stable phases that prevent TiO2 aggregation and phase transformation during hydrothermal aging, maintaining both high surface area and hydrothermal stability simultaneously.
Solution Approach 2:
The patent introduces localized doping of metal oxides at specific sites within the TiO2 structure. This local modification creates regions with enhanced stability while preserving the overall high surface area structure, allowing the catalyst to maintain both catalytic activity and hydrothermal stability under severe aging conditions.
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 AMOx catalyst exhibits lower ammonia light-off temperature (T70) and reduced N2O formation, maintaining high performance even after hydrothermal aging, compared to conventional catalysts.
Implementation Method 1
A platinum group metal (PGM) catalyst supported on TiO2 doped with 0-10% wt of SiO2, WO3, ZrO2, Y2O3, or La2O3, which maintains high ammonia oxidation activity and selectivity to N2 with reduced N2O formation
Implementation Method 2
TiO2 is doped with 0-10% wt of SiO2, WO3, ZrO2, Y2O3, La2O3, or a mixture thereof
Data Source
AI summary
The invention relates to a selective ammonia oxidation catalysts comprising a platinum group metal and a support comprising TiO2 doped with 0-10% by weight of SiO2, WO3, ZrO2, Y2O3, La2O3, or a mixture thereof. The invention further comprises methods for the manufacture of the selective ammonia oxidation catalysts, and integrated catalyst systems comprising the selective ammonia oxidation catalysts for treating an exhaust gas stream.