Reactive Filter In Situ Zeolite Coating Backpressure
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Solution Overview
Problem
Existing engine exhaust depolluting systems face challenges with clogging issues due to uncontrolled deposition of catalytic materials in porous substrates, leading to backpressure problems and inefficient filtration, particularly in selective catalytic reduction filters and oxidative reaction filters, which are exacerbated by the physical limits of pore size and porosity.
Innovation Solution
A reactive filter with a porous substrate having its internal surfaces directly coated with catalytic zeolite material through in situ hydrothermal synthesis, allowing for homogeneous coating and improved catalytic activity without relying on pore size or porosity, using a medium with zeolite precursors and active species precursors in an autoclave reactor at controlled temperatures and pressures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a porous substrate is coated with catalytic material using conventional processes, then catalytic activity is improved, but pore clogging occurs leading to backpressure issues
Solution Approach 1:
The catalytic material is pre-formed as small particles or crystallites before being deposited into the porous substrate. This preliminary preparation allows the material to be introduced in a controlled size and shape that prevents pore clogging while ensuring adequate catalytic activity on the substrate inner surfaces.
Solution Approach 2:
The invention changes the physical parameters of the catalytic material, specifically its size and shape, by forming it as small particles or crystallites with controlled dimensions. This parameter modification allows the material to fit within substrate pores without causing excessive deposition or clogging, resolving the contradiction between achieving sufficient catalytic coverage and maintaining low backpressure.
2Manufacturing precision
If pores of optimal size are used for particle filtration, then filtration efficiency is improved, but catalytic material deposition causes clogging
Solution Approach 1:
The catalytic material is applied selectively to the inner surfaces of the porous substrate pores rather than filling the entire pore volume. This localized deposition ensures that the pore channels remain open for efficient particle filtration while the coated surfaces provide the necessary catalytic activity for exhaust treatment.
Solution Approach 2:
The catalytic material is pre-formed as small particles with controlled size distribution before deposition. This preliminary sizing ensures that the particles are small enough to coat the pore surfaces uniformly without blocking the pore channels, thereby maintaining both filtration efficiency and pore patency.
3Object-affected harmful factors
If larger pores are used, then clogging is reduced, but filtration efficiency decreases
Solution Approach 1:
The invention changes the size parameters of the catalytic material particles, forming them with controlled small dimensions that allow them to effectively coat the inner surfaces of various pore sizes without causing clogging. This parameter control enables the use of optimal pore sizes for filtration while preventing the clogging that would normally occur with conventional coating materials.
4Strength
If low porosity substrate is used, then mechanical strength is improved, but catalytic material deposition causes excessive clogging
Solution Approach 1:
The catalytic material is deposited locally on the inner surfaces of the pores rather than filling the pore volume. This localized coating approach allows the use of low porosity substrates with good mechanical strength, as the catalytic material forms a thin surface layer that provides sufficient activity without blocking the limited pore space available in low porosity materials.
5Reliability
If high porosity substrate is used, then catalytic coating capacity is improved, but filtering capacity becomes insufficient
Solution Approach 1:
The catalytic material is applied selectively to the inner surfaces of the pores, maximizing the use of available pore surface area for catalysis. This approach allows high porosity substrates to achieve sufficient catalytic coating capacity while their inherent open structure maintains adequate filtering capacity, as the coating does not block the pore channels.
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 provides a reactive filter with enhanced catalytic activity and reduced backpressure, achieving efficient filtration with reduced catalytic material usage, maintaining efficiency with as little as 10 to 20 g of zeolite material per liter of substrate, while preventing clogging and optimizing pore size distribution.
Implementation Method 1
directly coated with a catalytic zeolite material resulting from an in situ hydrothermal synthesis
Implementation Method 2
combining particulate filter functions such as Diesel particulate filter functions (DPF function) and Selective Catalytic Reduction functions (SCR function)
Implementation Method 3
selective catalytic reduction filters or oxidative reaction filters
Data Source
AI summary
Disclosed is a reactive filter, that is a selective catalytic reduction filter or an oxidative reaction filter, including a porous substrate including internal pores having their inner surface, totally or partially, directly coated with a catalytic zeolite material resulting from an in situ hydrothermal synthesis. Also disclosed is a process for preparing such a reactive filter and the use thereof in an engine exhaust depolluting system.