Vanadium-Free SCR Catalyst with Iron Oxide Promoter
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Solution Overview
Problem
Current SCR DeNOx catalysts face challenges such as high costs due to tungsten shortages, toxicity concerns with vanadium, and inefficiencies at low temperatures, particularly in lean burn engine applications where NOx reduction is needed across a broad temperature range.
Innovation Solution
A catalyst composition featuring a mixed metal oxide support of titanium and zirconium with a promoter-rich surface, including oxides of silicon, boron, or manganese, which enhances low-temperature NOx reduction activity by depositing manganese or iron oxides, eliminating the need for vanadium and tungsten.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If vanadium oxide and tungsten trioxide are used as standard catalyst components, then catalytic performance for NOx reduction is improved, but cost increases due to tungsten shortages and health concerns arise from vanadium toxicity
Solution Approach 1:
The patent removes vanadium and tungsten from the catalyst composition, extracting the harmful and costly components while retaining the titania support structure. The invention achieves this by using iron oxide as the primary active component instead of vanadium oxide, thereby eliminating toxicity concerns and tungsten dependency while maintaining NOx reduction functionality.
Solution Approach 2:
The patent combines iron oxide with titania support and promotes the iron oxide component with alkali metal oxides or fluorides. This merging creates a new catalyst system where iron oxide provides the primary catalytic activity for NOx reduction, while the promoters enhance low-temperature performance, achieving effective catalysis without vanadium or tungsten.
2Object-affected harmful factors
If iron oxide is used as an alternative to vanadium oxide, then cost and toxicity issues are reduced, but low-temperature activity and selectivity deteriorate
Solution Approach 1:
The patent introduces alkali metal oxides (such as potassium oxide, sodium oxide) or fluorides as intermediary promoter substances. These promoters act as mediators that modify the iron oxide-titania catalyst surface, enhancing its low-temperature activity and selectivity for NOx reduction. The promoters facilitate the catalytic reaction at lower temperatures without requiring vanadium or tungsten.
3Temperature
If conventional SCR catalysts are used in lean burn engines, then NOx reduction is achieved at high temperatures, but performance drops significantly at low temperatures
Solution Approach 1:
The patent changes the chemical and physical parameters of the catalyst by using iron oxide instead of vanadium oxide as the active component and incorporating alkali metal promoters. This parameter change shifts the catalyst's optimal operating temperature range, enabling effective NOx reduction at lower temperatures typical of lean burn engine operation, while maintaining stability across a broad temperature range.
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 composition significantly improves NOx conversion efficiency at temperatures between 200° C. and 300° C., offering superior performance for lean burn engine applications with reduced costs and environmental concerns.
Implementation Method 1
A promoter-rich mixed metal oxide support surface enhances the low-temperature activity of manganese- or iron-based SCR catalysts
Implementation Method 2
deposited thereon is a promoter or promoters, and deposited on the promoter-rich mixed metal oxide support surface is an active catalyst component
Data Source
AI summary
Low temperature activity of a vanadium-free selective catalytic reduction catalyst is provided by a mixed metal oxide support containing oxides of titanium and zirconium, the support having a promoter deposited on the surface of the mixed metal oxide support, and further having an active catalyst component deposited over the promoter on the mixed metal oxide support surface. Suitable promoters include oxides of silicon, boron, aluminum, cerium, iron, chromium, cobalt, nickel, copper, tin, silver, niobium, lanthanum, titanium, and combinations thereof. Suitable active catalyst components include oxides of manganese, iron and cerium.