Sulfur-Tolerant CO Shift Catalyst via Low-Temp Spinel Formation
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Solution Overview
Problem
Sulfur-tolerant carbon monoxide shift conversion catalysts face issues with sintering, low crystallinity, low mechanical strength, poor anti-hydratability, and complex preparation methods, leading to reduced catalytic activity and specific surface area.
Innovation Solution
A sulfur-tolerant carbon monoxide shift conversion catalyst is prepared using a magnesium source, aluminum source, oxide flux, crystal growth agent, rare earth additive, CoO, and MoO3, with a method involving kneading, extrusion, drying, and calcination at lower temperatures to form a magnesium-alumina spinel carrier with improved crystallinity and mechanical strength, and impregnating with CoO and MoO3 to maintain high catalytic activity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the catalyst is prepared by co-precipitation or kneading with high calcination temperature (700-900°C), then the magnesia-alumina spinel phase has high degree of crystallinity, but the catalyst is susceptible to severe high-temperature sintering, resulting in low specific surface area and reduced catalytic activity
Solution Approach 1:
The patent changes the calcination temperature parameter from the conventional high range (700-900°C) to a lower range (500-650°C), which prevents severe sintering while still achieving sufficient crystallinity of the magnesia-alumina spinel phase. This parameter optimization resolves the contradiction between crystallinity and specific surface area.
Solution Approach 2:
The patent uses a composite carrier system consisting of magnesia-alumina spinel with added basic oxides (CaO, MgO, or BaO). This composite structure enhances the crystallinity and stability of the spinel phase at lower calcination temperatures while maintaining high specific surface area, thus resolving the contradiction between crystallinity and surface area.
2Manufacturing precision
If the calcination temperature is reduced to 500-650°C, then the catalyst is less susceptible to sintering and maintains higher specific surface area, but the magnesia-alumina spinel phase may have lower degree of crystallinity
Solution Approach 1:
The patent introduces basic oxides (CaO, MgO, or BaO) as additives to the magnesia-alumina spinel carrier. These basic oxides act as crystallization promoters that enable the spinel phase to achieve high degree of crystallinity at lower calcination temperatures (500-650°C), thus maintaining both high specific surface area and high crystallinity simultaneously.
Solution Approach 2:
The basic oxides (CaO, MgO, or BaO) serve as intermediary substances that facilitate the crystallization process at lower temperatures. They act as nucleation sites and promote the formation of well-crystallized spinel phase without requiring high calcination temperatures, thereby resolving the contradiction between low-temperature processing and crystallinity.
3Ease of manufacture
If conventional preparation methods are used, then the catalyst can be produced, but the preparation process is complex and produces large amounts of waste water
Solution Approach 1:
The patent eliminates the co-precipitation step from the conventional preparation process, which is the main source of waste water generation. By using direct mixing of precursors followed by low-temperature calcination, the process extracts out the problematic wet chemistry step while still achieving the desired spinel phase formation.
Solution Approach 2:
The patent employs a simplified preparation route that uses inexpensive, easily handleable precursor materials (magnesium carbonate, aluminum hydroxide) that can be directly mixed and calcined without requiring complex purification or washing steps, thereby reducing both process complexity and waste water generation.
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 catalytic activity, resistance to sulfur poisoning, and improved mechanical strength and stability, with a nano-sized active phase that enhances dispersion and activity, while the simplified preparation method reduces energy consumption and waste.
Implementation Method 1
calcining the semi-finished product at a temperature of 550-650° C. for a period of 6-13 hours to obtain a catalyst carrier
Implementation Method 2
the catalyst is generally susceptible to sintering and became inactivated
Implementation Method 3
impregnating with CoO and MoO3 to maintain high catalytic activity
Implementation Method 4
CO shift conversion refers to a process wherein CO is reacted with steam to form CO2 and H2 in the presence of a catalyst
Implementation Method 5
the carbon monoxide shift reaction is a highly exothermic catalytic reaction
Data Source
AI summary
The present invention discloses a sulfur tolerant carbon monoxide shift conversion catalyst, prepared by the following materials: magnesium source, aluminum source, oxide flux, crystal growth agent, rare earth additive, CoO, MoO3 and an acidic aqueous solution. A preparation method of the catalyst is provided, comprising the steps of: S1, Adding an aqueous acidic solution and a specific amount of rare earth additive to a specific amount of magnesium source, aluminum source, oxide flux and crystal growth agent, followed by kneading to produce a mixture; S2, Extruding the mixture to obtain an extruded strip product; S3, Drying the extruded strip product to give a semi-finished product; S4, Calcining the semi-finished product to obtain a catalyst carrier; S5, Impregnating the catalyst carrier with the active components CoO and MoO3 by an incipient-wetness impregnation method to obtain an impregnated product; and S6, Calcining the impregnated product to obtain the catalyst. The oxide flux and crystal growth agent can participate in a solid phase reaction between the magnesium source and aluminum source to form spinel structure, thereby improving the mechanical strength and stability of the spinel. The nano-sized active component can effectively improve the dispersion of the active component, and improve the catalytic activity of the granular boundary of the active component.