MOF Catalyst for NOx Reduction at Room Temperature

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Solution Overview

Problem

Current technologies fail to effectively reduce nitrogen oxides (NOx) in exhaust gases, particularly in Diesel engines, due to the lack of suitable catalysts that can operate in oxidizing environments and maintain efficiency at low temperatures without the use of costly reducing agents.

Innovation Solution

The use of metal-organic framework (MOF) solids, specifically Fe3OX[C6H3-(CO2)3]2 and Fe6O2X2[C12H6-(CO2)4]3, as catalysts that can reduce nitrogen oxides at room temperature without the need for reducing species, even in the presence of oxygen and water, by interacting with accessible metal centers to transform NOx into non-polluting gases like N2 and O2.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If conventional catalysts are used to reduce nitrogen oxides, then NOx reduction can be achieved, but high temperatures and reducing agents are required which increase energy consumption and system complexity

Engineering Contradiction:
Improvenitrogen oxide pollutionVSAvoidenergy consumption
Core Design Contradiction:
Object-affected harmful factorsVSUse of energy by moving object

Solution Approach 1:

The patent changes the operational parameters of the catalyst by using MOF materials that enable NOx reduction at room temperature without requiring high temperatures or reducing agents, fundamentally altering the energy input requirements of the deNOx process

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The MOF catalyst performs self-service by autonomously reducing NOx through its intrinsic metal centers without requiring external reducing agents or high energy input, making the system self-sufficient and eliminating the need for additional energy-consuming components

Inventive Principle:
Principle #25Self-service

2Productivity

If reducing agents are used to facilitate nitrogen oxide reduction, then catalytic activity is improved, but system complexity and cost increase

Engineering Contradiction:
Improvecatalytic activityVSAvoidsystem complexity
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The patent extracts and eliminates the requirement for reducing agents from the catalytic system, using MOF materials that inherently possess the capability to reduce NOx through their metal centers, thereby simplifying the overall system architecture

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The use of metal-organic framework composite materials combines metallic catalytic centers with organic linkers to create a novel catalyst that achieves high productivity without requiring additional reducing agents or complex system components

Inventive Principle:
Principle #40Composite materials

3Productivity

If high temperatures are applied to reduce nitrogen oxides, then reaction rate is improved, but energy consumption and thermal stability requirements increase

Engineering Contradiction:
Improvereaction rateVSAvoidoperating temperature
Core Design Contradiction:
ProductivityVSTemperature

Solution Approach 1:

The patent fundamentally changes the temperature parameter from high-temperature operation to room temperature catalysis by utilizing the unique properties of MOF materials, thereby maintaining high reaction rates without thermal energy input

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent replaces the thermal mechanism (heat-driven reactions) with a chemical mechanism based on MOF metal center activity, substituting thermal energy input with chemically-driven catalysis at ambient conditions

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

4Adaptability or versatility

If conventional catalysts operate in oxidizing environments, then they can handle Diesel exhaust, but their efficiency and stability deteriorate

Engineering Contradiction:
Improveenvironmental adaptabilityVSAvoidcatalyst stability
Core Design Contradiction:
Adaptability or versatilityVSReliability

Solution Approach 1:

The MOF composite material combines robust inorganic metal clusters with stable organic linkers to create a catalyst that maintains high reliability and stability in oxidizing environments, enabling effective NOx reduction in Diesel exhaust conditions

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The patent applies local quality by designing MOF structures where specific metal centers are positioned to interact with NOx molecules, creating localized active sites that maintain high catalytic efficiency and stability in oxidizing environments without requiring the entire system to be optimized for harsh conditions

Inventive Principle:
Principle #3Local quality

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 provides a highly effective, cost-efficient, and environmentally friendly method for reducing nitrogen oxides in various effluents, including vehicle exhausts, by achieving significant NOx conversion at low temperatures and maintaining catalyst stability and activity over multiple cycles.

Implementation Method 1

The MOF solids of the present invention are advantageously capable of eliminating nitrogen oxides from a liquid or gaseous effluent... DeNOx catalysis is a major challenge for our societies. It makes it possible to reduce or even avoid the public health consequences of toxic NOx gases

Methodology Applied
Scientific EffectCatalysis: Catalysis

Data Source

PatentEP2435183B1Use of a porous crystalline hybrid solid as a nitrogen oxide reduction catalyst and devices
Publication Date: 2021.11.24 CENT NAT DE LA RECH SCI (C N R S)
  • EP2435183B1 patent drawingFigure 1~2
  • EP2435183B1 patent drawingFigure 3~4
  • EP2435183B1 patent drawingFigure 5~6

AI summary

The present invention relates to the use of solids consisting of a metal-organic framework (MOF) and having the units of the following formula (I): MmOkXILp as a nitrogen-oxide catalyst. The present invention also relates to devices for enabling the implementation of said use. The nitrogen oxides in question are nitrogen monoxide and nitrogen dioxide, collectively referred to as NOx. The MOF solids of the present invention are advantageously capable of removing nitrogen oxides from a liquid or gaseous effluent, for example from water, from the exhaust gases of a vehicle, factory, workshop, laboratory, stored products, urban air vents, etc., without any reducing agent and at a low temperature. The DeNOx catalysis is a major issue for our societies. The invention can be used for reducing or even avoiding the consequences for public health of the toxic NOx gases resulting from human activity.