SAPO-34 Catalyst with Oxide Layer for Hydrothermal Stability
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Solution Overview
Problem
Existing catalysts for diesel engine exhaust emissions, particularly those using zeolites, face challenges in maintaining activity under harsh hydrothermal conditions and low temperature performance, leading to instability and increased costs due to high washcoat loading requirements.
Innovation Solution
A catalyst material comprising a metal-exchanged SAPO-34 with an oxide layer deposited using surface deposition methods, such as atomic layer deposition, to enhance hydrothermal stability and low temperature performance without blocking the pores, thereby improving NOx reduction efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If zeolite catalysts are used for SCR reactions, then catalytic activity is achieved, but hydrothermal stability deteriorates under harsh conditions
Solution Approach 1:
The patent uses SAPO-34 molecular sieve as a composite material combining silicon, aluminum, and phosphorus in a specific framework structure. This composite composition provides both catalytic activity for SCR reactions and enhanced hydrothermal stability compared to conventional zeolites, resolving the contradiction between achieving catalytic activity and maintaining stability under harsh conditions
Solution Approach 2:
The patent modifies the catalyst composition by controlling the Si/Al ratio and incorporating specific metal ions (Cu, Fe, Co, Ni, Zn, or Mn) at controlled concentrations. These parameter changes optimize both the catalytic activity and hydrothermal stability, allowing the catalyst to maintain performance under harsh operating conditions while achieving the required SCR conversion efficiency
2Productivity
If high washcoat loading is used to improve low temperature performance, then catalytic activity is enhanced, but manufacturing cost increases
Solution Approach 1:
The patent optimizes the washcoat loading to a specific range (0.5-5.0 g/in³) and controls the metal ion concentration (0.1-10 wt%) to achieve high catalytic activity at low temperatures without requiring excessive material loading. This parameter optimization maintains productivity while reducing manufacturing costs associated with high washcoat loading
Solution Approach 2:
The patent incorporates specific metal ions (Cu, Fe, Co, Ni, Zn, or Mn) into the SAPO-34 framework at controlled concentrations to enhance low-temperature catalytic activity locally. This targeted incorporation provides the necessary low temperature performance without requiring high overall washcoat loading, thereby reducing manufacturing costs
3Productivity
If metal ions are exchanged into SAPO-34 to enhance catalytic activity, then NOx conversion efficiency is improved, but catalyst stability under hydrothermal conditions deteriorates
Solution Approach 1:
The patent controls the metal ion concentration within a specific range (0.1-10 wt%) and optimizes the Si/Al ratio to balance catalytic activity and hydrothermal stability. This parameter control ensures high NOx conversion efficiency while preventing excessive metal ion content from compromising hydrothermal stability
Solution Approach 2:
The patent creates a composite structure where metal ions are incorporated into the SAPO-34 framework in controlled amounts. This composite approach enhances catalytic activity for NOx conversion while the SAPO-34 framework provides structural stability under hydrothermal conditions, resolving the contradiction between activity enhancement and stability maintenance
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 material exhibits improved stability and performance across a wide temperature range, maintaining high NOx conversion efficiency even after hydrothermal aging, reducing the need for high washcoat loading and associated costs.
Implementation Method 1
an oxide layer deposited using surface deposition methods, such as atomic layer deposition
Implementation Method 2
catalyst material for abatement of exhaust gas emissions from a lean burn engine... useful in methods and systems to catalyze the reduction of nitrogen oxides
Implementation Method 3
a metal-exchanged SAPO-34 material... wherein the metal is Cu, Fe, Co, Ni, Zn or Mn
Data Source
AI summary
A catalyst material for abatement of exhaust gas emissions from a lean burn engine is provided, the catalyst material including a metal-exchanged SAPO-34 material, and an oxide layer at least partially covering an outside surface of the SAPO-34 material, wherein the oxide layer is not substantially blocking the pores of the SAPO-34 material.