Shell Catalyst Uniformity via Toroidal Fluidization
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Solution Overview
Problem
Existing shell catalysts for producing vinyl acetate monomer (VAM) face limitations in achieving uniform concentration and thickness of catalytically active species, leading to non-uniform product selectivity and activity, with the thinnest achievable shell thickness being around 100 µm and non-uniform concentration over large areas.
Innovation Solution
A method involving a fluidized bed process where porous shaped catalyst support bodies rotate elliptically or toroidally, allowing for uniform spraying and drying of solutions containing catalytically active species, resulting in catalysts with a uniform concentration of active species across 90% of the shell thickness and a standard deviation of shell thickness in batches less than or equal to 20%.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If impregnation method is used to apply catalytically active species to catalyst support, then the catalyst can be produced with loaded support, but the shell thickness becomes non-uniform and concentration of active species becomes non-uniform over large areas
Solution Approach 1:
The catalyst support bodies are fluidized and set into motion within the coating device, creating dynamic movement patterns that ensure uniform exposure to the coating solution. The supports circulate continuously through the coating zone, allowing consistent application of catalytically active species across all surfaces, thereby achieving uniform shell thickness and concentration distribution.
Solution Approach 2:
A fluidizing gas flow is introduced to suspend and move the catalyst support bodies within the coating device. This pneumatic system creates a fluidized bed where supports are continuously circulated and coated uniformly with the solution containing catalytically active species, ensuring precise and consistent shell formation.
2Ease of manufacture
If impregnation method is used to apply catalytically active species, then catalyst production is simplified, but the minimum achievable shell thickness is limited to around 100 µm
Solution Approach 1:
The continuous dynamic circulation of catalyst support bodies in the fluidized state allows for precise control of coating deposition. The supports repeatedly pass through the coating zone, enabling gradual and uniform buildup of thin shells with consistent thickness distribution, achieving minimum shell thicknesses below 100 µm with high uniformity.
Solution Approach 2:
The fluidizing gas flow rate and coating solution parameters are optimized to control the deposition process. By adjusting these parameters, extremely thin and uniform shells can be formed through controlled diffusion and adsorption of catalytically active species onto the support surfaces.
3Device complexity
If catalyst support bodies are stationary during coating, then the coating process is simpler, but uniform concentration of active species cannot be achieved across large areas
Solution Approach 1:
The catalyst support bodies are fluidized and set into continuous motion within the coating device, creating dynamic movement patterns that ensure uniform exposure to the coating solution. The supports circulate continuously through the coating zone, allowing consistent application of catalytically active species across all surfaces, thereby achieving uniform shell thickness and concentration distribution.
4Reliability
If shell thickness is reduced to improve product selectivity, then selectivity increases, but achieving uniform thin shells becomes more difficult with conventional methods
Solution Approach 1:
The continuous dynamic circulation of catalyst support bodies in the fluidized state allows for precise control of coating deposition. The supports repeatedly pass through the coating zone, enabling gradual and uniform buildup of thin shells with consistent thickness distribution, achieving minimum shell thicknesses below 100 µm with high uniformity.
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 produces shell catalysts with increased activity and uniformity in catalytically active species distribution, enabling the production of catalysts with very thin shells and improved product selectivity, surpassing the limitations of prior art by achieving uniformity and high activity across large areas.
Implementation Method 1
loading the device (10) with porous shaped catalyst support bodies and producing a catalyst support shaped bodies fluidized bed by means of a process gas (40), the catalyst support shaped bodies rotating in the fluidized bed
Implementation Method 2
spraying the shaped catalyst support bodies with solution containing a catalytically active species or a precursor thereof, the shaped catalyst support bodies rotating elliptically or toroidally in the fluidized bed
Implementation Method 3
Drying the shaped catalyst support bodies sprayed with the solution
Data Source
Figure 1A
Figure 1B
Figure 2A
AI summary
The invention relates to a method for producing a shell catalyst which comprises a porous molded catalyst support having an outer shell in which at least one catalytically active species is contained. The aim of the invention is to provide a shell catalyst production method which allows production of shell catalysts that have a substantially uniform concentration in catalytically active species over a relatively large part of their shell thickness and that have a substantially uniform shell thickness. The method according to the invention makes use of a device (10) which is adapted to produce a fluid bed of molded catalyst supports by means of a process gas (40), the molded catalyst supports revolving in said bed on elliptical or toroidal, preferably toroidal, orbits. Said method comprises the following steps: a) feeding molded catalyst supports to the device (10) and producing a fluid bed of molded catalyst supports by means of a process gas (40), the molded catalyst supports revolving in said bed on elliptical or toroidal, preferably toroidal, orbits; b) impregnating an outer shell of the molded catalyst supports with a catalytically active species or a precursor thereof by spraying the molded catalyst supports that revolve in the fluid bed on elliptical or toroidal orbits with a solution that contains a catalytically active species or a precursor thereof; c) drying the molded catalyst supports that are sprayed with said solution.