Monolithic Fe-Co Catalyst Coating for NH3 Conversion in FCC Flue Gas
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Solution Overview
Problem
Existing catalysts for reducing NOx emissions in incomplete regeneration flue gas from catalytic cracking devices have low catalytic conversion activity for reduced nitrides like NH3, leading to ammonia-nitrogen exceeding standards and salt deposition in downstream equipment, and existing methods for complete regeneration flue gas are energy-inefficient.
Innovation Solution
A structured monolithic catalyst with a coating of active components, including Fe, Co, and noble metals like Ru, is applied to improve catalytic conversion activity for reduced nitrides, particularly in incomplete regeneration flue gas, by dispersing these metals on the catalyst's surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing catalysts are used for reducing NOx emissions in incomplete regeneration flue gas, then the catalytic cracking process can continue operation, but the catalytic conversion activity for reduced nitrides like NH3 is low, causing ammonia-nitrogen to exceed standards and salt deposition in downstream equipment
Solution Approach 1:
The patent uses a composite catalyst structure combining metal oxides (Fe2O3, Co3O4, MnO2, CuO, ZnO) supported on alumina with a specific pore structure. This composite material approach enhances the catalytic conversion activity for reduced nitrides while preventing ammonia-nitrogen emission and salt deposition in downstream equipment.
Solution Approach 2:
The catalyst employs an alumina support with controlled pore size distribution (0.3-0.8 μm average pore diameter) and specific surface area (150-300 m²/g). The porous structure provides high surface area for active sites while facilitating mass transfer of reactants and products, improving catalytic efficiency for NH3 conversion.
2Object-generated harmful factors
If complete combustion mode is used for regeneration, then CO and NOx emissions can be controlled, but energy consumption increases and the process becomes less efficient
Solution Approach 1:
The patent changes the operational parameters by implementing incomplete combustion mode with controlled oxygen content (0.5-5% excess oxygen) and specific temperature ranges (600-800°C). This parameter optimization allows selective conversion of reduced nitrides to N2 while maintaining energy efficiency and reducing overall energy consumption compared to complete combustion.
Solution Approach 2:
The patent converts the potentially harmful reduced nitrides (NH3, HCN) present in incomplete combustion flue gas into beneficial N2 through catalytic conversion. The incomplete combustion mode, which would normally produce more pollutants, is transformed into a beneficial process by using the reducing atmosphere to facilitate selective catalytic reduction of NOx to N2.
3Loss of energy
If reduced nitrides like NH3 are not fully oxidized in the CO boiler, then energy is conserved, but the remaining NH3 causes ammonia-nitrogen to exceed standards and reacts with SOx to generate ammonium salt precipitates
Solution Approach 1:
The patent applies preliminary catalytic conversion of reduced nitrides to N2 before the flue gas enters the CO boiler for energy recovery. By performing this conversion in advance (pre-treatment), the subsequent energy recovery process can proceed without the risk of NH3 oxidation to NOx or formation of ammonium salts, thus maintaining both energy efficiency and environmental compliance.
Solution Approach 2:
The catalyst acts as an intermediary device between the regenerator and CO boiler. It selectively converts reduced nitrides to N2 in the flue gas stream, mediating the interaction between the incomplete combustion products and the downstream energy recovery system, thereby preventing harmful reactions while conserving energy.
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 effectively reduces NOx emissions in incomplete regeneration flue gas, preventing ammonia-nitrogen excess and salt deposition, while maintaining energy efficiency and product distribution in the FCC process.
Implementation Method 1
a coating of active components disposed on inner surface and/or outer surface of the structured monolithic carrier... the structured monolithic catalyst... has high catalytic conversion activity for reduced nitrides
Data Source
Figure 1
AI summary
The present invention relates to a structured monolithic catalyst for reducing NOx emission in a flue gas, the preparation method and the use thereof. The catalyst comprises: a structured monolithic carrier and a coating of active components, wherein the coating of active components comprises active metal components and a substrate, wherein the active metal components comprise a first metal element, a second metal element, a third metal element and a fourth metal element, wherein the first metal element includes Fe and Co, wherein the weight ratio of Fe and Co is 1 : (0.05-20) on an oxide basis, wherein the second metal element is at least one selected from the group consisting of the metal elements of the Group IA and/or IIA, wherein the third metal element is at least one selected from the group consisting of the non-noble metal elements of the Groups IB to VIIB, and wherein the fourth metal element is at least one selected from the group consisting of the noble metal elements. The catalyst in accordance with the present invention has high catalytic conversion activity for reduced nitrides, is obtainable by a simple method, and when used in a FCC process, can effeciently reduce NOx emission in the incomplete regeneration flue gas.