Segmented Exhaust Catalyst for Low-Temperature Purification
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Solution Overview
Problem
Existing exhaust gas purification catalysts are inadequate for efficiently purifying hydrocarbons (HC), carbon monoxide (CO), and nitrogen oxides (NOx) at low temperatures and struggle with responsiveness when dealing with sudden changes in exhaust gas temperature and flow rate.
Innovation Solution
An exhaust gas purification catalyst with a region containing palladium and yttrium, structured in a three-dimensional format with varying yttrium concentrations in different regions, enhancing heat resistance and catalytic activity, particularly with a higher yttrium concentration in the second region.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a conventional exhaust gas purification catalyst is used, then the catalyst structure is simple, but the catalytic responsiveness to sudden temperature changes and low-temperature exhaust gas is insufficient
Solution Approach 1:
The catalyst is divided into multiple regions (first region, second region, third region) with different compositions and functions. The first region contains Pt and Pd for oxidation reactions, the second region contains Rh for NOx reduction, and the third region contains Pt and Pd for additional oxidation. This segmentation allows each region to be optimized for specific functions, improving overall catalytic responsiveness to temperature changes and low-temperature exhaust gas.
Solution Approach 2:
Different precious metal components are distributed non-uniformly across different regions of the catalyst. The first region has Pt and Pd with specific concentrations optimized for oxidation, the second region has Rh concentrated for NOx reduction, and the third region has Pt and Pd for additional oxidation capacity. This local quality variation enhances catalytic activity at different temperature conditions and improves responsiveness to sudden exhaust gas changes.
2Productivity
If the catalyst treats large amounts of high-temperature exhaust gas instantaneously, then the space velocity increases suddenly, but the catalyst temperature lags behind exhaust gas temperature causing insufficient purification
Solution Approach 1:
The first region containing Pt and Pd is positioned at the inlet side to perform oxidation reactions before the exhaust gas reaches the second region. This preliminary oxidation of HC and CO generates heat in advance, helping to raise the catalyst temperature more quickly when high-temperature exhaust gas is introduced suddenly, reducing the temperature lag between exhaust gas and catalyst.
Solution Approach 2:
The three-region structure ensures continuous catalytic action across different temperature conditions. The first region handles oxidation at lower temperatures, the second region handles NOx reduction at intermediate temperatures, and the third region provides additional oxidation capacity at higher temperatures. This continuity ensures that purification activity is maintained across the full range of exhaust gas temperature variations.
3Temperature
If the catalyst is designed for low-temperature purification, then the catalytic activity at low temperature improves, but the durability and performance under high space velocity conditions deteriorates
Solution Approach 1:
The catalyst composition is designed with specific precious metal concentrations in each region optimized for different operating conditions. The first region has Pt and Pd concentrations optimized for low-temperature oxidation, while the third region has additional Pt and Pd to maintain oxidation capacity under high space velocity conditions. This parameter variation across regions allows the catalyst to maintain both low-temperature activity and durability under high load conditions.
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 effectively purifies HC, CO, and NOx at low temperatures and maintains durability even under high space velocity conditions, ensuring efficient exhaust gas treatment across varying temperature and flow rate changes.
Implementation Method 1
an exhaust gas purification catalyst capable of purifying hydrocarbons (HC), carbon monoxide (CO), and nitrogen oxides (NOx) in exhaust gas at low temperatures
Data Source
AI summary
In order to provide an exhaust gas purification catalyst capable of purifying hydrocarbons, carbon monoxide, and nitrogen oxides in exhaust gas at low temperatures, the exhaust gas purification catalyst according to the present invention includes: a region (2) containing palladium and yttrium on a three-dimensional structure (1), and a first region (3) and a second region (4) provided on the region (2) in order from an inflow side of exhaust gas to an outflow side of exhaust gas. The concentration of yttrium contained in the first region (3) and/or the second region (4) is higher than the concentration of yttrium contained in the region (2).