Zeolite-TiO2 SCR Catalyst Composition for Sulfur-Tolerant NOx Removal
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Solution Overview
Problem
Existing SCR catalysts are prone to deactivation by ammonium-sulfur compounds (AS and ABS) at both low and high temperatures, leading to performance degradation and reduced lifetime, especially when exposed to exhaust gases with high sulfur content.
Innovation Solution
An SCR catalyst comprising 0.01 to 70 wt% zeolite with a 5 Å or more average pore size, 25 to 90 wt% titanium dioxide, 4 to 10 wt% vanadium pentoxide, and optionally 0.01 to 15 wt% tungsten trioxide, designed to tolerate high sulfur concentrations and maintain denitrification performance across a 180° C. to 400° C. temperature range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If conventional SCR catalysts are used in low-temperature operation, then fuel costs are reduced, but catalyst deactivation by ammonium-sulfur compounds increases
Solution Approach 1:
The patent employs zeolite with specific pore structures (0.01 to 70 wt%, average pore size of 5 Å or more) to selectively adsorb and trap ammonium-sulfur compounds, preventing them from deactivating the catalyst active sites while allowing the SCR reaction to proceed at low temperatures
Solution Approach 2:
The patent creates a composite catalyst system combining zeolite with titanium dioxide (25 to 90 wt%) and vanadium pentoxide (4 to 10 wt%), where each component contributes specific functions: zeolite for sulfur compound trapping, TiO2 for structural support and sulfur tolerance, and V2O5 for catalytic activity in nitrogen oxide reduction
2Productivity
If SCR catalysts operate in high-sulfur exhaust gas, then denitrification can be maintained, but catalyst deactivation by ammonium bisulfate fills pores and deteriorates performance
Solution Approach 1:
The patent converts the harmful effect of ammonium-sulfur compounds into a beneficial trapping mechanism by using zeolite's porous structure to selectively adsorb these compounds, transforming what would be a deactivation mechanism into a protective filtration process that extends catalyst lifetime
Solution Approach 2:
The patent optimizes specific parameters including zeolite pore size (5 Å or more), aluminum-to-silicon ratio (1:5 to 1:30), and catalyst composition ratios to enhance sulfur tolerance while maintaining denitrification performance across a wide temperature range (180°C to 400°C)
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 enhanced sulfur tolerance and denitrification efficiency, with a nitrogen oxide conversion rate of 40 to 96% within 200 to 250° C., and effective regeneration at higher temperatures, outperforming conventional catalysts in maintaining activity and extending operational life.
Implementation Method 1
ammonia which does not participate in the reduction of nitrogen oxide reacts with sulfur oxide in exhaust gas to produce ammonium salt. In the ammonium salt, ammonium bisulfate (ABS) is present in a liquid phase at a temperature of about 280° C., an SCR operating temperature, and fills pores of a catalyst to deteriorate performance of the catalyst
Implementation Method 2
The SCR technology uses ammonia as a reductant, and a reaction between ammonia and nitrogen oxide of an SCR catalyst bed may be performed according to the following reaction formula 1. 4NO+4NH3+O2→4N2+6H2O
Implementation Method 3
a reaction between ammonia and nitrogen oxide of an SCR catalyst bed may be performed according to the following reaction formula 1
Implementation Method 4
a temperature is raised using a burner to seta catalyst operating temperature, so that high fuel costs may be incurred
Data Source
AI summary
Provided is an SCR catalyst for removing nitrogen oxides (NOx) from exhaust gas, comprising: 0.01-70 wt % of zeolite having an average pore size of 5 Å or more; 25-90 wt % of titanium dioxide (TiO2); and 4-10 wt % of vanadium pentoxide (V2O5). The SCR catalyst according to the present invention exhibits denitrification performance in a low-temperature area that is superior to that of a conventional SCR catalyst, has improved tolerance for a sulfur compound, and also has an excellent regeneration rate.