Outlet-Side Catalyst Coating Reduces DPF Backpressure
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing diesel particulate filters (DPFs) coated with SCR catalysts experience increased backpressure, which negatively impacts engine performance and fuel economy, due to the high pressure drop across the filter caused by soot deposits and catalyst washcoats.
Innovation Solution
Coating the DPF from the outlet side with a catalyst washcoat having large particle sizes relative to the filter's mean pore size, while keeping the inlet side substantially free of catalyst, reduces soot-loaded backpressure and maintains gas conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a catalyst washcoat is applied to a wall-flow filter substrate to reduce exhaust system size, then the filter serves dual functions (soot removal and catalytic conversion), but the backpressure across the filter increases, reducing engine performance and fuel economy
Solution Approach 1:
The catalyst coating is segmented by application location (inlet side vs. outlet side) and particle size. The patent divides the coating strategy into different zones with different catalyst particle size distributions, allowing the filter to achieve catalytic functionality while managing pressure drop characteristics through differentiated coating regions.
Solution Approach 2:
Different regions of the filter substrate receive different catalyst coating characteristics. The inlet side receives catalyst with a first particle size distribution optimized for catalytic activity, while the outlet side receives catalyst with a second particle size distribution optimized for maintaining gas flow and reducing backpressure. This local differentiation resolves the contradiction between catalytic effectiveness and pressure loss.
2Reliability
If a high surface area catalyst washcoat is applied to increase catalytic activity, then NOx reduction efficiency improves, but the pressure drop across the filter increases, negatively impacting engine performance
Solution Approach 1:
The patent changes the particle size distribution parameter of the catalyst washcoat based on location. By adjusting this physical parameter (particle size) rather than changing the chemical composition, the system maintains catalytic activity while optimizing flow characteristics. Larger particles on the outlet side reduce pressure drop while smaller particles on the inlet side maximize catalytic surface area for NOx reduction.
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
This approach significantly decreases backpressure across the filter, improving engine performance and fuel economy by effectively trapping soot and reducing NOx concentrations in lean-burn exhaust gases while maintaining efficient gas flow.
Implementation Method 1
a catalyst composition coated from the outlet side of the substrate... reduce the concentration of NOx in exhaust gas
Implementation Method 2
trapping at least a portion of the soot on and/or in the diesel particulate filter while allowing the exhaust gas to pass through
Data Source
Figure 1A~1B
Figure 2A~2B
Figure 3
AI summary
Provided is a diesel particulate filter capable of removing soot from an exhaust gas while operating at low backpressure, the filter comprising (a) a wall-flow filter substrate (23) having a mean pore size, an inlet side (30), an outlet side (32), and a porous interior between the inlet and outlet sides; and (b) a catalyst composition (44) coated from the outlet side of the substrate, wherein the catalyst composition has a d5Q particle size distribution, wherein the d50 particle size distribution is greater than or equal to the mean pore size divided by 4.9, and wherein the inlet side is substantially free of a catalyst coating.