Alkali-Doped Cobalt Spinel Catalyst for Low-Temperature N2O Decomposition
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Solution Overview
Problem
Existing catalysts for N2O decomposition in nitric acid plants face challenges in achieving high conversion rates and stability under real operating conditions, particularly at low temperatures and in the presence of O2 and H2O, with limited stability and efficiency under industrial space velocities.
Innovation Solution
A non-stoichiometric spinel-type catalyst with a formula Co3O4-x/2Ay, where x and y are adjusted to create oxygen vacancies and a mesoporous structure, enhancing catalytic activity and stability through controlled alkali doping during precipitation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional catalysts are used for N2O decomposition at high temperatures, then conversion rate is improved, but catalyst stability and resistance to deactivation deteriorate
Solution Approach 1:
The patent changes the operating temperature parameter from high temperature (750-940°C) to low temperature (250-500°C) range, and modifies the catalyst composition by incorporating alkali metals (K, Na, Cs) and controlling oxygen vacancy concentration (x=0.02-0.3 in Co3O4-x/2Ay), thereby achieving high conversion rates without sacrificing catalyst stability
Solution Approach 2:
The patent creates a composite catalyst system by combining cobalt spinel with alkali metal elements (K, Na, Cs) and controlling the stoichiometry through oxygen vacancies, forming a non-stoichiometric spinel structure that exhibits both high activity and stability under real operating conditions
2Productivity
If catalysts are designed for high activity, then N2O conversion is improved, but resistance to O2 and H2O deteriorates
Solution Approach 1:
The patent modifies the catalyst composition by introducing alkali metals (K, Na, Cs) with specific concentrations (y=0.06-0.18) and controlling oxygen vacancy levels (x=0.02-0.3), which changes the electronic and structural properties of the cobalt spinel to enhance both catalytic activity and resistance to poisoning by O2 and H2O
Solution Approach 2:
The patent creates localized oxygen vacancies within the cobalt spinel structure at specific concentrations (x=0.02-0.3), which locally modifies the electronic structure and creates active sites that are both highly active for N2O decomposition and resistant to deactivation by O2 and H2O
3Productivity
If space velocity is increased to improve productivity, then N2O conversion efficiency is improved, but catalyst stability deteriorates
Solution Approach 1:
The patent optimizes the catalyst composition with alkali metals (y=0.06-0.18) and oxygen vacancies (x=0.02-0.3) to create a catalyst that maintains structural stability even at high space velocities (GHSV=15000-50000 h⁻1), allowing high productivity without sacrificing stability
4Use of energy by stationary object
If low temperature operation is implemented, then energy consumption is reduced, but catalytic activity deteriorates
Solution Approach 1:
The patent modifies the catalyst composition by incorporating alkali metals (K, Na, Cs) and controlling oxygen vacancy concentration to lower the activation energy barrier for N2O decomposition, enabling high catalytic activity (T50=250-260°C) at low temperatures without sacrificing productivity
Solution Approach 2:
The patent creates localized oxygen vacancies within the cobalt spinel structure that act as active sites with reduced activation energy, enabling the catalyst to operate efficiently at low temperatures (250-500°C) while maintaining high N2O conversion rates
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 achieves over 98% N2O conversion at temperatures below 350°C and maintains stability for at least 65 hours under real conditions, outperforming existing catalysts in terms of conversion efficiency and durability.
Implementation Method 1
The most effective technologies for nitrous oxide removal in nitric acid plants are catalytic decomposition processes
Implementation Method 2
a non-stoichiometric spinel-type crystalline structure, the general formula of which is Co3O4-x/2Ay, where x has a value of between 0.02 and 0.3
Implementation Method 3
its particular use in the N2O decomposition reaction... the primary particle size being equivalent to a crystallite size of between 5 and 30 nm
Data Source
AI summary
The present invention concerns a material with a non-stoichiometric spinel-type crystalline structure based on cobalt oxide doped with alkaline elements, its production process for obtaining it by precipitation with controlled washing, and its particular use as a highly active catalyst in the N2O decomposition reaction. Therefore, we understand that the present invention is in the area of green industry aimed at reducing N2O emissions into the atmosphere.