Stacked Strand Catalyst Monolith for Low Pressure Drop
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Solution Overview
Problem
Current catalysts with high external surface areas and packing fractions suffer from mechanical instability and high pressure drops in packed bed reactors, leading to inefficient gas flow and channeling, while sintering at high temperatures deteriorates catalytically active metal dispersion.
Innovation Solution
A method for producing three-dimensional porous catalyst monoliths by extruding a paste of catalytically active metal or catalyst support particles through nozzles with diameters over 500 μm, forming strands in alternating layers oriented at angles to create a monolith structure with varying inter-strand distances, reducing pressure drop and enhancing mechanical stability without the need for high-temperature sintering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If smaller catalyst extrudates are used to obtain high external surface areas and high packing fractions, then mass transfer performance is improved, but pressure drop increases and mechanical strength becomes insufficient
Solution Approach 1:
The catalyst structure is segmented into a hierarchical pore system with macro-pores (50-500 μm) for low resistance flow and micro-pores (<50 μm) for high surface area reactions. This segmentation allows small catalyst particles to be arranged in a macro-porous monolith structure that provides both high mass transfer efficiency and mechanical strength.
Solution Approach 2:
The invention transitions from traditional one-dimensional extruded catalyst shapes to a three-dimensional monolith structure with channels extending in multiple directions. This dimensional change creates a network of intersecting macro-channels that reduce flow resistance while maintaining high catalyst surface area through integrated micro-porous walls.
2Strength
If high-temperature sintering is applied to prepare robust catalyst structures, then mechanical stability is improved, but catalytically active metal dispersion deteriorates
Solution Approach 1:
The invention changes the temperature parameter from high-temperature sintering (>1000°C) to low-temperature drying and gentle calcination (<500°C). This parameter change preserves the dispersion of catalytically active metals while still providing sufficient mechanical strength through the monolith's structural design and binder selection.
Solution Approach 2:
A specifically designed binder material serves as an intermediary that provides mechanical strength to the monolith structure without requiring high-temperature sintering. The binder is selected to decompose at low temperatures, leaving a robust ceramic structure that maintains metal dispersion while providing the necessary mechanical stability.
3Ease of operation
If alternating layers with varying inter-strand distances are created to reduce pressure drop, then flow homogeneity is improved, but manufacturing complexity increases
Solution Approach 1:
The monolith structure incorporates local variations in inter-strand distances, creating regions of different porosity optimized for specific functions. Macro-channels with larger spacing facilitate low-resistance flow, while regions with tighter spacing provide higher catalyst surface area, all within a single integrated structure.
4Ease of manufacture
If extrusion nozzle diameter is increased to simplify manufacturing, then production ease is improved, but strand diameter and pressure drop increase
Solution Approach 1:
The extrusion process is segmented into multiple passes, with each pass creating a layer of strands that are subsequently assembled into the final monolith. This allows the use of larger nozzle diameters for easier manufacturing while the final segmented structure maintains small effective strand diameters for low pressure drop.
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 method results in a lower pressure drop across individual monoliths and reactor beds, ensuring homogeneous gas flow and maintaining the dispersion of catalytically active metals, thus improving catalyst performance and reactor efficiency.
Implementation Method 1
a) Preparing a paste of metal, metal alloy or metal compound particles of catalytically active metal or catalyst support particles in a liquid diluent... b) extruding the paste of step a) through one or more nozzles having a diameter larger than 500 μm to form strands
Implementation Method 2
c) drying the porous monolith precursor to remove the liquid diluent
Data Source
AI summary
A three-dimensional porous catalyst, catalyst carrier or absorbent monolith of stacked strands of catalyst, catalyst carrier or absorbent material, composed of alternating layers of linear spaced-apart parallel strands, wherein the strands in alternating layers are oriented at an angle to one another, wherein the distance between inner spaced-apart parallel strands is larger than the distance between outer spaced-apart parallel strands in at least a part of the layers of the monolith.