Nickel Diatomaceous Earth Catalyst Heat Resistance
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Solution Overview
Problem
Nickel catalysts used in hydrogenation reactions with ammonia solvent suffer from low heat resistance and catalytic activity deterioration due to sintering, making it challenging to maintain performance over time, especially when exposed to both hydrogen and ammonia simultaneously.
Innovation Solution
A nickel diatomaceous earth catalyst is developed with specific properties, including a weight loss rate of 0.05-2.0% at 400-600°C, nickel crystallite diameter of 30-100 Å, and a specific surface area of 60-180 m2/g, produced using a precipitation method involving an alkaline solution as a precipitant, followed by drying, calcination, and reduction treatments, to enhance heat resistance and catalytic performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a nickel catalyst is used in hydrogenation reactions with ammonia solvent, then catalytic activity is achieved, but heat resistance deteriorates due to sintering when exposed to both hydrogen and ammonia simultaneously
Solution Approach 1:
The patent introduces a specific support material (silica-alumina composite or diatomaceous earth) as an intermediary between the nickel catalyst and the reaction environment. This support acts as a mediator that stabilizes the nickel particles, preventing direct interaction between the catalyst and the sintering-inducing atmosphere of hydrogen and ammonia, thereby maintaining both catalytic activity and heat resistance
Solution Approach 2:
The patent employs composite material structures, specifically combining nickel with silica-alumina composite supports or diatomaceous earth. This composite approach creates a synergistic system where the support material provides structural stability and heat resistance while the nickel component maintains catalytic activity, resolving the contradiction between catalytic performance and thermal stability
2Reliability
If the nickel catalyst is heat-treated at high temperature to improve heat resistance, then sintering is reduced, but catalytic activity decreases due to particle aggregation
Solution Approach 1:
The patent applies local quality by creating non-uniform nickel particle distributions on the support surface, with smaller particles in regions that require high catalytic activity and larger particles in regions that provide thermal stability. The support material itself has localized properties that prevent sintering in critical areas while maintaining overall heat resistance
Solution Approach 2:
The patent utilizes parameter changes by controlling the reduction temperature and atmosphere during catalyst activation. By optimizing the reduction temperature (typically 300-500°C) and using controlled hydrogen treatment, the nickel particles are transformed from oxide to metallic state with enhanced stability, achieving both heat resistance and maintained catalytic activity without excessive sintering
3Productivity
If the nickel catalyst is used for extended periods to maintain productivity, then catalytic sintering occurs, but catalytic activity and selectivity gradually decrease
Solution Approach 1:
The patent applies preliminary action by performing pre-treatment steps during catalyst preparation, including controlled reduction, aging, and stabilization processes. These preliminary actions create a more stable nickel particle structure before the catalyst enters service, preventing rapid sintering during initial operation and extending the catalyst's productive lifespan while maintaining activity
Solution Approach 2:
The patent ensures continuity of useful action by designing a catalyst structure that maintains stable performance over extended operation periods. The support material continuously stabilizes the nickel particles, and periodic regeneration treatments can restore activity without requiring complete catalyst replacement, thereby maintaining continuous productivity while preventing irreversible deactivation
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 exhibits excellent heat resistance during hydrogenation reactions in liquid ammonia and hydrogen atmospheres, extending its lifespan and maintaining high catalytic activity by controlling the crystallite diameter and surface area through precise production methods.
Implementation Method 1
a precursor produced by precipitating a compound containing nickel hydroxide and nickel carbonate on the surface of the support using the precipitation method
Implementation Method 2
which is fixed to pore walls and then dried and calcined
Implementation Method 3
heat-treated with steam to produce a nickel catalyst excellent in both hydrogenation activity and heat resistance
Implementation Method 4
a nickel catalyst excellent in both hydrogenation activity and heat resistance
Implementation Method 5
Hydrogenation reaction using an ammonia solvent has been widely conducted and a typical example thereof may include synthesis of amines from nitriles
Data Source
AI summary
A nickel diatomaceous earth catalyst having a weight loss rate measured by hydrogen-TG at 400 to 600° C. of 0.05 to 2.0%.