Washcoat Suspension Coating of Shell Catalysts
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Solution Overview
Problem
Existing methods for applying washcoat suspensions to support structures in the production of shell catalysts face challenges in achieving uniform layer thickness, leading to inconsistencies in both individual and batch production.
Innovation Solution
A method involving the creation of a fluid bed where support structures circulate elliptically or toroidally, using a process gas to impregnate and dry the structures, and optionally calcine them, ensuring a uniform coating by controlling fluidization velocity and using specific fluid-bed devices like Innojet Ventilus or AirCoater for even distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If coating drums or fluid-bed units are used to apply washcoat suspension to support structures, then the support structures can be coated with catalytically active species, but the layer thickness becomes non-uniform both within individual shells and across batches
Solution Approach 1:
The support structures are made to move dynamically within the fluid bed rather than remaining stationary. The structures circulate continuously in the fluid bed, ensuring all surfaces are exposed to the washcoat suspension uniformly, which resolves the non-uniform layer thickness problem while maintaining batch consistency
Solution Approach 2:
A fluid bed system using gas flow is employed to suspend and circulate the support structures. The pneumatic fluidization ensures uniform distribution of washcoat suspension across all support structure surfaces, achieving both within-shell and between-batch uniformity that mechanical coating methods cannot provide
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
This approach results in support structures with largely uniform layer thickness, enhancing the homogeneity and quality of shell catalysts, as demonstrated by reduced standard deviation in shell thickness across batches.
Implementation Method 1
producing a fluid bed of support structures in which the support structures circulate elliptically or toroidally, preferably toroidally
Implementation Method 2
impregnating the support structures with a washcoat suspension by spraying the support structures circulating elliptically or toroidally in the fluid bed with the washcoat suspension
Implementation Method 3
drying the support structures sprayed with the washcoat suspension
Data Source
AI summary
A method for applying a washcoat suspension to a support structure. To provide coatings with largely uniform thickness starting from washcoat suspensions, the method uses a device (10) set up to produce, by means of a process gas (40), a fluid bed of support structures in which the support structures circulate elliptically or toroidally, the method comprising the steps of:a) charging the device (10) with support structures and producing a support-structure fluid bed by means of a process gas (40), wherein the support structures circulate in the fluid bed elliptically or toroidally, preferably toroidally;b) impregnating the support structures with a washcoat suspension by spraying the support structures circulating elliptically or toroidally in the fluid bed with the washcoat suspension;c) drying the support structures sprayed with the washcoat suspension; andd) optionally calcining the support structures loaded with the solids contents of the washcoat suspension.