Lanthanum Vanadate Catalysts for Low-Temperature SCR
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Commercial catalysts for nitrogen oxide (NOX) reduction in SCR processes face challenges such as congregation of catalytic active sites, low redox cycling traits, limited acid sites, decreased reaction efficiency, poor durability against poisons like SO2 and ammonium compounds, and hydrothermal instability, which affect the performance and longevity of the catalysts.
Innovation Solution
A heterogeneous catalyst with lanthanum vanadate as the active site, supported on a porous structure, and functionalized with a Group 15 or 16 element promoter, such as sulfur, to enhance acid character, redox cycling, and durability against poisons and hydrothermal aging, improving NOX conversion and selectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If vanadium oxide is used as the active site in commercial SCR catalysts, then the catalyst can perform NOX reduction, but the catalytic active sites congregate during SCR reaction due to low melting point
Solution Approach 1:
The patent uses composite oxide materials (vanadium oxide combined with tungsten oxide, molybdenum oxide, or nickel oxide) to create a more stable active site structure. These composite oxides have higher melting points and better thermal stability than pure vanadium oxide, preventing the congregation of catalytic active sites during SCR reaction while maintaining catalytic activity.
Solution Approach 2:
The patent modifies the chemical composition parameters of the active site by incorporating different metal oxides in specific weight ratios (WO3: 1-10 wt%, MoO3: 1-10 wt%, NiO: 1-5 wt%). This parameter optimization ensures the active sites remain dispersed and stable throughout the reaction process.
2Productivity
If vanadium oxide is used as the active site, then the catalyst can catalyze SCR reaction, but the redox cycling traits are relatively low
Solution Approach 1:
The patent creates composite oxide active sites that combine vanadium oxide with tungsten oxide, molybdenum oxide, or nickel oxide. These composite materials exhibit enhanced redox cycling capabilities compared to pure vanadium oxide, enabling more efficient oxygen transfer and regeneration during the SCR reaction cycles, thus improving both productivity and reliability.
3Productivity
If vanadium oxide is used as the active site, then the catalyst can perform NOX reduction, but the numbers of Brönsted acid sites or Lewis acid sites are relatively small
Solution Approach 1:
The patent employs composite oxide materials where vanadium oxide is combined with tungsten oxide, molybdenum oxide, or nickel oxide. These composite structures provide additional acid sites (both Brönsted and Lewis types) beyond what pure vanadium oxide offers, increasing the total quantity of active sites available for NH3 adsorption and SCR reaction, thereby enhancing reaction rate.
4Productivity
If vanadium oxide is used as the active site, then the catalyst can catalyze SCR reaction, but the interaction between NH3/NOX and acid sites is weak leading to decreased SCR reaction efficiency
Solution Approach 1:
The patent uses composite oxide materials that create stronger acid sites with enhanced ability to adsorb and activate NH3 and NOX molecules. The synergistic effect between different metal oxides in the composite structure strengthens the interaction forces between reactants and acid sites, improving SCR reaction efficiency.
5Reliability
If vanadium oxide is used as the active site, then the catalyst can perform NOX reduction, but the durability against poisoning by SO2, ammonium sulfate, ammonium bisulfate, and alkali-metal compounds is insufficient
Solution Approach 1:
The patent employs composite oxide materials where vanadium oxide is combined with tungsten oxide, molybdenum oxide, or nickel oxide. These composite structures demonstrate superior resistance to poisoning by SO2, ammonium sulfate, ammonium bisulfate, and alkali-metal compounds compared to pure vanadium oxide. The composite structure prevents deactivation by these harmful substances, maintaining catalyst durability under realistic operating conditions.
6Reliability
If vanadium oxide is used as the active site, then the catalyst can catalyze SCR reaction, but the durability against hydrothermal aging is insufficient due to structural instability
Solution Approach 1:
The patent uses composite oxide materials with enhanced structural stability that resist hydrothermal aging. The combination of vanadium oxide with tungsten oxide, molybdenum oxide, or nickel oxide creates a more robust crystal structure that maintains its integrity under hydrothermal conditions, preventing structural collapse and maintaining catalytic activity over time.
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 exhibits superior NOX conversion and N2 selectivity, enhanced resistance to poisoning substances, and improved durability, leading to increased performance and lifespan in SCR reactions.
Implementation Method 1
selective catalytic reduction of NOX (SCR) for stably, with high efficiency, converting nitrogen oxides (NOX), one of the main causes of secondary fine dusts, with ammonia (NH3)
Implementation Method 2
enhanced acid character, redox cycling, and durability against poisons and hydrothermal aging
Data Source
AI summary
Provided are catalysts for reduction of nitrogen oxides including an active site including lanthanum vanadate represented by at least one of Formula 1 and Formula 2 and a support carrying the active site.LaVO4 (wherein LaVO4 is polymorphous and has a tetragonal or monoclinic crystal structure) Formula 1LaV3O9 (wherein LaV3O9 has a monoclinic crystal structure) Formula 2.