Ceramic Candle Filter Catalyst for SCR NOx Conversion
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing catalysts for selective catalytic reduction (SCR) of nitrogen oxides require high vanadium content, which can lead to excessive SO2 oxidation and formation of ammonium bisulphate, and there is a lack of information on suitable vanadium to titanium ratios for ceramic candle filters.
Innovation Solution
A catalyst comprising a ceramic candle filter substrate with a coating of an oxidic metal carrier containing titanium and vanadium oxide, where the vanadium to titanium mass ratio is between 0.03 to 0.27, and the catalytic metal oxide is adsorbed onto the surface, with optional inclusion of tungsten, molybdenum, and antimony oxides, prepared using an aqueous impregnation liquid and thermal activation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high vanadium content is used in the catalyst, then effective NOx conversion is achieved, but excessive SO2 oxidation occurs leading to ammonium bisulphate formation
Solution Approach 1:
The patent applies parameter changes by optimizing the vanadium to titanium mass ratio to a specific range (0.03 to 0.27). This quantitative parameter adjustment allows the catalyst to achieve effective NOx conversion while preventing excessive SO2 oxidation, thereby resolving the contradiction between conversion efficiency and harmful byproduct formation.
Solution Approach 2:
The patent uses a composite catalyst system combining vanadium oxide with titanium oxide carrier and optional promoter oxides (tungsten, molybdenum, or antimony). This composite material approach creates a synergistic effect where the titanium carrier supports the vanadium active sites while promoters enhance selectivity, achieving high NOx conversion with reduced SO2 oxidation compared to pure vanadium catalysts.
2Productivity
If high vanadium content is used to ensure catalytic activity, then NOx removal efficiency improves, but the formation of ammonium bisulphate increases
Solution Approach 1:
The patent optimizes the vanadium to titanium mass ratio parameter within the range of 0.03 to 0.27. This parameter control ensures sufficient vanadium content for high NOx removal efficiency while limiting excessive vanadium that would lead to ammonium bisulphate formation, thus balancing productivity with substance loss prevention.
Solution Approach 2:
The patent converts the potentially harmful high vanadium content into a benefit by carefully controlling it within an optimal range. The titanium oxide carrier and promoter oxides transform the system so that vanadium acts selectively for NOx reduction rather than non-selective oxidation, turning what could be a harmful excess into a controlled, beneficial catalytic component.
3Ease of manufacture
If there is insufficient information on vanadium to titanium ratios, then catalyst development is hindered, but with proper ratio specification, optimal performance can be achieved
Solution Approach 1:
The patent performs preliminary action by establishing and specifying the optimal vanadium to titanium mass ratio range (0.03 to 0.27) in advance of catalyst manufacturing. This pre-determined parameter guidance eliminates the need for extensive trial-and-error during production, making catalyst development easier and more predictable while preventing the loss of critical formulation information.
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 effective NOx conversion with reduced SO2 oxidation, allowing for optimal NOx removal while minimizing the formation of ammonium bisulphate, and the specified vanadium to titanium ratio ensures efficient catalytic activity without excessive vanadium usage.
Implementation Method 1
a coating which comprises an oxidic metal carrier comprising an oxide of titanium and a catalytic metal oxide which comprises an oxide of vanadium wherein the catalytic metal oxide is adsorbed onto the surface of the oxidic metal carrier
Implementation Method 2
a catalyst for use in the selective catalytic reduction (SCR) of nitrogen oxides by reaction with ammonia
Implementation Method 3
4 NO+4 NH3+O2→4 N2+6 H2O
Implementation Method 4
an aqueous impregnation liquid comprising one or more catalyst metal precursor compounds dispersed on nanoparticles of an oxidic metal carrier
Implementation Method 5
the thus catalyzed substrate is activated by calcination at elevated temperatures either in a production process or when installed
Data Source
AI summary
A catalyst for use in the selective catalytic reduction (SCR) of nitrogen oxides. The catalyst comprises a ceramic candle filter substrate and a coating. The coating comprises an oxidic metal carrier comprising an oxide of titanium and a catalytic metal oxide which comprises an oxide of vanadium. The mass ratio of vanadium/titanium is 0.03 to 0.27, the mass ratio being calculated based on the mass of vanadium metal and titanium metal. The catalyst comprises from about 1 to about 10% by weight of the catalytically active material. The catalytic metal oxide is adsorbed onto the surface of the oxidic metal carrier.