Exhaust Catalyst Rhodium Loading Upstream Honeycomb
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Solution Overview
Problem
Conventional exhaust-gas purifying catalysts exhibit low catalytic activity at low temperatures, making it difficult to effectively purify exhaust gases immediately after engine startup.
Innovation Solution
An exhaust-gas purifying catalyst design featuring a mantle with two or more honeycomb-shaped supports, where rhodium (Rh) is loaded in a higher amount on the upstream side, enhancing ignition and purifying performance while reducing the overall loading amount of catalytic ingredients compared to platinum (Pt) and palladium (Pd).
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the loading amount of catalytic ingredients is increased to improve purifying performance, then the catalytic activity improves, but the cost increases due to higher noble metal consumption
Solution Approach 1:
The patent applies local quality by concentrating rhodium loading specifically on the upstream-side catalyst support substrate where exhaust gases first enter. This creates a high-activity ignition zone at the inlet to handle low-temperature conditions, while downstream substrates use lower loading amounts, optimizing overall performance while reducing total noble metal consumption.
Solution Approach 2:
The patent changes the parameter of catalytic ingredient distribution by using different loading amounts of rhodium on different catalyst support substrates. The upstream substrate has higher loading (0.8 g/L or more) to ensure ignition activity, while downstream substrates have lower loading, achieving parameter optimization across the catalyst structure.
2Reliability
If conventional catalyst designs are used, then manufacturing is simpler, but purifying performance at low temperatures is insufficient
Solution Approach 1:
The patent segments the catalyst into multiple catalyst support substrates with different rhodium loading amounts. The upstream substrate has high loading for ignition, while downstream substrates have lower loading for continued purification. This segmentation allows targeted optimization for low-temperature performance without uniformly increasing complexity throughout the entire catalyst structure.
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 improved purifying and ignition performance at low temperatures with reduced noble metal consumption, effectively purifying exhaust gases even when the engine is started, and maintaining efficiency throughout engine cycles.
Implementation Method 1
A catalytic ingredient is loaded on the loading layer. The exhaust-gas purifying catalysts convert nitrogen oxides (NOx), hydrocarbons (HC) and carbon monoxide (CO), which are contained in exhaust gases, into unharmful nitrogen, carbon dioxide and water, respectively, by the action of catalytic ingredients.
Data Source
AI summary
An exhaust-gas purifying catalyst includes a mantle, two or more honeycomb-shaped supports fastened in the mantle so as to be separated at intervals, and a catalytic layer disposed on the respective honeycomb-shaped supports. The honeycomb-shaped supports include a first honeycomb-shaped support, disposed on a most upstream side of the mantle with respect to a flow of exhaust gases, and a second honeycomb-shaped support, disposed next to the first honeycomb-shaped support on a downstream side of the mantle with respect to the flow of exhaust gases. The catalytic layer includes a loading layer formed on the respective honeycomb-shaped supports, and a catalytic ingredient loaded on the loading layer. The catalytic layer disposed on the first honeycomb-shaped support includes at least Rh in a loading amount of 0.8 g or more with respect to 1 L of an apparent volume of the first honeycomb-shaped support.