Ni-NiAl2O4-CaAl12O19 Catalyst for DRM Stability
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Solution Overview
Problem
Existing nickel-based catalysts for dry reforming of methane (DRM) suffer from deactivation due to carbon deposition and sintering at high temperatures, leading to poor stability and activity.
Innovation Solution
A nickel-nickel aluminum spinel-calcium hexaaluminate composite catalyst is developed through a calcination-reduction method, where nickel is effectively controlled in a sub-surface layer, enhancing the interaction with the support and inhibiting sintering and carbon deposition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If nickel-based catalysts are used for DRM at high temperatures, then high activity is achieved, but carbon deposition and sintering cause deactivation and poor stability
Solution Approach 1:
The patent employs a composite catalyst system consisting of Ni particles supported on CaAl12O19 (calcium hexaaluminate) with surface-modified nickel aluminum spinel layers. This composite structure combines the high catalytic activity of Ni with the thermal stability and coke resistance of the spinel-modified hexaaluminate support, resolving the contradiction between activity and stability at high temperatures
Solution Approach 2:
The catalyst features a non-uniform structure where nickel aluminum spinel is selectively formed on the surface of the CaAl12O19 support particles, creating a core-shell like architecture. The interior maintains high Ni dispersion for activity, while the surface spinel layer provides localized protection against carbon deposition and sintering, achieving both high productivity and reliability
2Productivity
If nickel particles are dispersed on Al-based support, then high initial activity is achieved, but phase transformation and carbon deposition reduce active sites and stability
Solution Approach 1:
The patent converts the potentially harmful effect of carbon deposition into a beneficial protective mechanism. The nickel aluminum spinel surface layer acts as a physical barrier that prevents carbon from reaching and deactivating the Ni active sites, while also preventing Ni particle migration and sintering. This spinel layer, which might seem to block active sites, actually protects and maintains them over long periods, achieving both high initial activity and long-term stability
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 high activity and stability during DRM at high temperatures, maintaining CH4 and CO2 conversion rates of 88.3% to 95.2% and 82.8% to 93.1% respectively for 50 hours, with a long operation life of 1,000 hours or more.
Implementation Method 1
drying and calcining the mixed precursor sequentially to obtain a nickel aluminum spinel-calcium hexaaluminate composite precursor
Implementation Method 2
placing the nickel aluminum spinel-calcium hexaaluminate composite precursor in a flowing hydrogen atmosphere, and subjecting the nickel aluminum spinel-calcium hexaaluminate composite precursor to reduction reaction to obtain the nickel-nickel aluminum spinel-calcium hexaaluminate composite catalyst
Implementation Method 3
The nickel-nickel aluminum spinel-calcium hexaaluminate composite catalyst exhibits high activity and strong resistance to carbon deposition and sintering, and could efficiently catalyze the DRM reaction at high temperature
Data Source
AI summary
Provided are a nickel-nickel aluminum spinel-calcium hexaaluminate composite catalyst and a preparation method and use thereof. The method for preparing the nickel-nickel aluminum spinel-calcium hexaaluminate composite catalyst includes: mixing a nickel salt metal precursor, an aluminum salt metal precursor, a calcium salt metal precursor, and an organic fuel to obtain a mixed precursor; drying and calcining the mixed precursor sequentially to obtain a nickel aluminum spinel-calcium hexaaluminate composite precursor; and placing the nickel aluminum spinel-calcium hexaaluminate composite precursor in a flowing hydrogen atmosphere, and subjecting the nickel aluminum spinel-calcium hexaaluminate composite precursor to reduction reaction to obtain the nickel-nickel aluminum spinel-calcium hexaaluminate composite catalyst.