Layered Diesel Oxidation Catalyst Composite for CO and HC Conversion

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Solution Overview

Problem

Diesel engines face challenges in effectively treating exhaust emissions, particularly with palladium-based diesel oxidation catalysts showing higher light-off temperatures and susceptibility to sulfur poisoning, which hampers hydrocarbon and carbon monoxide oxidation, especially at low engine temperatures.

Innovation Solution

A layered diesel oxidation catalyst composite is designed with a palladium-containing layer separated from a zeolite hydrocarbon trap layer and an oxygen storage component, using a high surface area refractory metal oxide support to minimize platinum poisoning and enhance light-off performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of substance

If palladium-based diesel oxidation catalyst is used, then cost is reduced compared to platinum, but light-off temperature increases and sulfur poisoning susceptibility increases

Engineering Contradiction:

Improveprecious metal lossVSAvoidlight-off temperature

Core Design Contradiction:

Loss of substanceVSTemperature

Solution Approach 1:

The catalyst is divided into multiple functional layers: a first layer containing palladium on refractory oxide support for oxidation catalysis, and a second layer containing zeolite for hydrocarbon adsorption. This segmentation allows each layer to perform its specific function optimally, with the palladium layer operating at lower temperatures and the zeolite layer managing hydrocarbons independently.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The refractory oxide support (such as ceria or ceria-zirconia) acts as an intermediary between the palladium catalyst and the exhaust gas stream. It provides oxygen storage and release capabilities, facilitating oxidation reactions at lower temperatures and reducing the direct exposure of palladium to sulfur-containing gases, thereby mitigating sulfur poisoning.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Loss of substance

If palladium-based diesel oxidation catalyst is used, then cost is reduced compared to platinum, but catalytic activity at low temperatures decreases

Engineering Contradiction:

Improveprecious metal lossVSAvoidcatalytic activity

Core Design Contradiction:

Loss of substanceVSProductivity

Solution Approach 1:

The catalyst uses a composite structure combining palladium with refractory oxide supports (such as ceria or ceria-zirconia). This composite material leverages the high catalytic activity of palladium for oxidation reactions while the refractory oxide provides oxygen storage and release capabilities, enabling effective catalysis at lower temperatures and improving overall productivity.

Inventive Principle:

Principle #40Composite materials

3Ease of manufacture

If conventional single-layer catalyst structure is used, then manufacturing is simpler, but hydrocarbon storage capacity and catalytic performance are insufficient

Engineering Contradiction:

Improvecatalyst structure simplicityVSAvoidhydrocarbon storage capacity

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The multi-layer catalyst structure provides multiple functions within a single catalyst assembly: the first layer performs oxidation catalysis for CO and HC conversion, while the second layer provides hydrocarbon adsorption and storage. This multi-functionality ensures reliable hydrocarbon management throughout the catalyst's operational lifecycle.

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 solution achieves improved light-off performance for hydrocarbons and carbon monoxide oxidation, reducing precious metal loss and maintaining catalytic activity, even at low temperatures, while optimizing the use of palladium and platinum components.

Implementation Method 1

A layered diesel oxidation catalyst composite is designed with a palladium-containing layer separated from a zeolite hydrocarbon trap layer

Methodology Applied

Scientific EffectAdsorption: Adsorption

Implementation Method 2

oxidation catalysts comprising precious metals such as platinum group metals (PGM) dispersed on a refractory metal oxide support are known for use in treating the exhaust of diesel engines in order to convert both hydrocarbon and carbon monoxide gaseous pollutants by catalyzing the oxidation of these pollutants to carbon dioxide and water

Methodology Applied

Scientific EffectCatalysis: Catalysis

Implementation Method 3

an oxygen storage component, wherein the oxygen storage component is separated from the majority of the catalytically active precious metal component

Methodology Applied

Scientific EffectOxygen storage: Absorption (physical)

Data Source

PatentEP2387460B1Diesel oxidation catalyst composite with layer structure for carbon monoxide and hydrocarbon conversion

Publication Date: 2021.06.30 BASF CORPORATON

Figure 1~2

AI summary

Provided is a catalyst composition, in particular a diesel oxidation catalyst, for the treatment of exhaust gas emissions, such as the oxidation of unburned hydrocarbons (HC), and carbon monoxide (CO). More particularly, the present invention is directed to a catalyst structure comprising at least two, specifically three distinct layers, at least one of which contains an oxygen storage component (OSC) that is present in a layer separate from the majority of the platinum group metal (PGM) components, such as palladium and platinum.