Dual-Layer NOx Reduction Catalyst for Wide Temperature Range
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Solution Overview
Problem
Conventional SCR catalysts exhibit significantly reduced NOx reduction performance at low temperatures below 200°C, making them ineffective for processing gases like diesel engine exhaust gas.
Innovation Solution
A NOx reduction catalyst system comprising a catalyst substrate with a NOx absorption component (Ba, V, Ce, or La) and a NOx purification component (γ-Al2O3 and zeolite β) in combination, along with an ammonia source addition device, which absorbs NOx at low temperatures and releases it for reduction at higher temperatures, ensuring effective NOx purification across a wide temperature range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional SCR catalyst is used, then the catalyst structure is simple and easy to manufacture, but the NOx reduction performance is drastically lowered at low temperature (200°C or below)
Solution Approach 1:
The catalyst is divided into two distinct functional layers: a first layer containing NOx absorption components (Ba, V, Ce, or La) that operates at low temperatures, and a second layer containing NOx purification components (γ-Al2O3 and zeolite β) that operates at high temperatures. This segmentation allows each layer to specialize in specific temperature ranges, resolving the contradiction between low-temperature absorption performance and high-temperature purification capability.
Solution Approach 2:
The invention changes the operational parameters of different catalyst components by assigning the first layer to absorb NOx at low temperatures (200°C or below) and the second layer to purify NOx at high temperatures (above 200°C). This parameter-based differentiation enables the catalyst system to maintain high NOx reduction performance across a wide temperature range.
2Reliability
If a dual-layer catalyst structure is implemented, then the NOx processing performance across wide temperature range is improved, but the device complexity increases
Solution Approach 1:
The invention merges two different catalytic functions (NOx absorption and NOx purification) into a single integrated catalyst substrate. The first layer with NOx absorption components and the second layer with NOx purification components are combined in a unified structure, allowing the system to achieve wide temperature range performance without requiring separate catalyst units or complex control systems.
Solution Approach 2:
The catalyst substrate is designed with multi-functionality by incorporating both NOx absorption and purification capabilities in different layers. This universal design allows a single catalyst device to handle both low-temperature and high-temperature NOx processing, reducing the need for multiple separate systems and simplifying the overall device architecture.
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 NOx reduction catalyst system achieves high NOx processing performance from low to high temperatures, effectively purifying NOx in both automobile exhaust gases and power plant flue gases, with optimized component ratios and structures enhancing purification efficiency.
Implementation Method 1
The NOx reduction catalyst of the present invention absorbs NOx by the NOx absorption component in a low temperature range (at 200°C or below, for example)
Implementation Method 2
The released NOx is reduced by the NOx purification component activated under high temperature
Data Source
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AI summary
A NOx reduction catalyst is provided which reduces NOx in processing gas. The NOx reduction catalyst includes a catalyst substrate containing an oxide, a NOx absorption component, and a NOx purification component.