Modified Bauxite Catalyst Carrier for CO Shift Heat Management
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Solution Overview
Problem
The CO sulfur-tolerant shift catalysts used in high-pressure CO shift reactions exhibit excessively high catalytic activity, leading to sintering and potential 'runaway' phenomena due to high reaction temperatures, which poses safety risks and catalyst deactivation when applied to feed gases with high CO concentrations and steam gas ratios.
Innovation Solution
A catalyst carrier with modified bauxite, alumina or pseudo-boehmite, and magnesium oxide, along with active ingredients CoO and MoO3, is developed, featuring a macroporous structure and controlled calcination process to achieve moderate catalytic activity and enhanced anti-hydration and mechanical strength, preventing catalyst deactivation and sintering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If CO sulfur-tolerant shift catalyst with high catalytic activity is used, then CO conversion rate is improved, but reaction temperature increases causing sintering and catalyst deactivation
Solution Approach 1:
The patent changes the physical and chemical parameters of the catalyst carrier by controlling pore size distribution (macro-pores of 3-10 μm), specific surface area (1.5-3.0 m²/g), and pore volume (0.45-0.95 mL/g). These parameter adjustments optimize mass transfer and heat dissipation while maintaining moderate catalytic activity, preventing runaway reactions even at high CO conversion rates.
Solution Approach 2:
The patent uses composite carrier materials including modified bauxite (40-70 wt%), alumina (10-30 wt%), and magnesium oxide (10-30 wt%). This composite structure combines the advantages of each material: bauxite provides mechanical strength and thermal stability, alumina enhances surface area and active sites, and magnesium oxide improves heat resistance and structural stability at high temperatures, collectively preventing sintering and deactivation.
2Productivity
If high steam gas ratio is used to promote shift reaction, then hydrogen production is improved, but catalyst hydration and deactivation are accelerated
Solution Approach 1:
The patent employs a carrier with specifically designed porous structure featuring macro-pores (3-10 μm) and controlled pore volume (0.45-0.95 mL/g). This porous structure facilitates rapid steam diffusion and product evacuation, reducing residence time of water vapor near active sites and minimizing hydration reactions while maintaining high hydrogen production efficiency.
Solution Approach 2:
The patent adjusts the hydrophobicity parameter of the carrier surface through modification treatments and material selection, creating a hydrophobic environment that repels water molecules. This parameter change reduces the affinity between water vapor and catalyst active sites, preventing hydration deactivation even under high steam gas ratio conditions (1.0-1.8).
3Productivity
If high CO concentration feed gas is processed, then hydrogen production efficiency is improved, but reaction heat increases causing runaway phenomenon
Solution Approach 1:
The patent utilizes a carrier with hierarchical porous structure including macro-pores (3-10 μm) that serve as heat dissipation channels. These large pores enable efficient heat transfer and convection, rapidly conducting reaction heat away from active sites and preventing localized temperature spikes that could lead to runaway reactions, while still allowing high CO concentration processing.
Solution Approach 2:
The patent deliberately designs the catalyst with moderate intrinsic activity rather than maximum activity, using controlled pore distribution and surface area to limit the reaction rate. This partial action approach ensures that even with high CO concentration and steam gas ratio, the heat generation remains manageable and can be effectively dissipated, preventing thermal runaway while maintaining high hydrogen production efficiency.
4Productivity
If catalyst carrier with high surface area is used to increase active sites, then catalytic activity is improved, but mechanical strength and anti-hydration performance decrease
Solution Approach 1:
The patent creates a composite carrier system where modified bauxite (40-70 wt%) provides robust mechanical strength and thermal stability, alumina (10-30 wt%) contributes high surface area (1.5-3.0 m²/g) and active sites, and magnesium oxide (10-30 wt%) enhances hydrophobicity and structural stability. This composite formulation achieves the optimal balance between high catalytic activity and excellent mechanical strength with anti-hydration performance.
Solution Approach 2:
The patent applies different material properties to different functional requirements: the bulk structure uses high-strength modified bauxite for mechanical integrity, the surface incorporates alumina for high surface area and activity, and hydrophobic modifications are applied to specific surface regions to provide anti-hydration performance. This local quality differentiation allows simultaneous optimization of activity, strength, and hydration resistance.
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 carrier maintains stable performance under high CO and steam conditions, controlling reaction heat and preventing catalyst bed runaway, while effectively adsorbing impurities and maintaining mechanical integrity, thus enabling safe and efficient hydrogen production.
Implementation Method 1
a catalyst carrier with shift and adsorption purification performance
Implementation Method 2
Carbon Monoxide Shift refers to a process that reacting CO containing feed gas with water vapor to form CO2 and H2 in the presence of a catalyst
Data Source
AI summary
The present invention provides a catalyst carrier with shift and adsorption purification performance, comprising modified bauxite in the raw material components which fluxing and pore forming effects. Most iron oxide contained in the bauxite is removed after modification, so that there are a large amount of highly active aluminosilicate compounds in the modified bauxite. When preparing the catalyst, the aluminosilicate compound serves as a low melting point flux and can significantly increase the migration rate of magnesium and aluminum ions during the calcinating process and promote the generation of MgAl2O4 at low temperatures, thereby the catalyst carrier of the present invention has strong anti-hydration capacity and mechanical strength. In addition, when the modified bauxite is used as macroporous hard template for the preparation of the catalyst, macro pores can be formed in the structure of the catalyst carrier after calcinating treatment, so that the catalyst carrier of the present invention has strong adsorption purification ability on macromolecular particles including oil pollution and dust.