Li2NH-Based Catalyst for Low-Temperature Ammonia Synthesis
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Solution Overview
Problem
Current catalysts for ammonia synthesis and decomposition, such as Fe-based and Ru-based catalysts, require high temperatures and pressures, leading to high energy consumption and inefficient ammonia production, while non-Fe(Ru)-based catalysts lack industrialization due to insufficient activity and stability.
Innovation Solution
Development of nitrogen or hydrogen-containing compounds of main group elements, such as Li2NH, loaded on supports like Li2O or metal nitrides, which exhibit catalytic activity in ammonia synthesis and decomposition reactions at lower temperatures and pressures, with specific mass ratios optimized for enhanced performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional Fe-based or Ru-based catalysts are used for ammonia synthesis, then catalytic activity can be achieved, but high temperature and pressure conditions are required leading to high energy consumption
Solution Approach 1:
The invention changes the chemical composition parameters of the catalyst from conventional Fe-based or Ru-based catalysts to Li2NH-based catalysts with specific mass ratios (Li2NH:Li2O = 1:0.1 to 1:0.5 or Li2NH:metal nitride = 1:0.1 to 1:0.5). This compositional parameter change enables the catalyst to achieve high ammonia synthesis activity at lower temperatures and pressures, directly resolving the contradiction between productivity and energy consumption
Solution Approach 2:
The invention creates a composite catalyst system by combining Li2NH with Li2O or metal nitrides in specific mass ratios. This composite material approach synergistically enhances the catalytic activity and stability, allowing the system to maintain high productivity under milder conditions with lower energy consumption compared to conventional single-component catalysts
2Use of energy by moving object
If non-Fe(Ru)-based catalysts are developed to reduce energy consumption, then lower operating conditions can be used, but catalytic activity and stability are insufficient for industrialization
Solution Approach 1:
The invention develops a composite catalyst system combining Li2NH with Li2O or metal nitrides in specific mass ratios (1:0.1 to 1:0.5). This composite structure provides both high catalytic activity and exceptional stability, with the supporting materials (Li2O or metal nitrides) anchoring the Li2NH active sites and preventing their aggregation or decomposition, thereby enabling industrialization of non-Fe(Ru)-based catalysts
Solution Approach 2:
The invention optimizes the local composition and structure of the catalyst by controlling the mass ratio of Li2NH to supporting materials. This local quality optimization ensures that the active Li2NH sites are distributed uniformly and maintained in their most active form throughout the catalyst structure, achieving both high activity and long-term stability required for industrial application
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 proposed catalyst system achieves comparable activity to conventional Ru-based catalysts under low-temperature, low-pressure conditions, with ammonia synthesis rates reaching 95 umol gcat^-1h^-1 at 400°C and demonstrating stable catalytic performance in ammonia decomposition.
Implementation Method 1
Li2NH and Li3N could conduct a reversible hydrogen absorption-desorption reaction at moderate temperatures, and hydrogenated products are LiNH2 and LiH
Implementation Method 2
LiNH2 can be decomposed to emit NH3 in the temperature range of 200 to 500°C with the peak temperature at about 370°C
Implementation Method 3
Li2NH or Li3N can exhibit catalytic effect in the further decomposition of ammonia of the gaseous product
Data Source
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AI summary
The present invention relates to a catalyst for ammonia synthesis and ammonia decomposition. The catalyst includes a nitrogen-containing compound of a main group element and a related support and an additive. The present invention is a novel catalytic material, which exhibits good catalytic activity in ammonia synthesis and ammonia decomposition reactions.