An experimental study in the wetting of porous powders

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Wood, Thomas A. (2019). An experimental study in the wetting of porous powders. University of Birmingham. Eng.D.

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Abstract

Manufacture of emission control catalysts involves preparation of concentrated washcoat slurries, which are coated onto monoliths. This thesis considers the early stages of washcoat preparation, involving the wetting and dispersion of highly porous catalyst support powders into suspension.

An optimal geometry for powder incorporation in mechanically agitated batch mixing vessels is found experimentally using a design of experiments approach. The effect on this optimal geometry of increasing solid concentration in the slurry is shown to have a significant impact on the energy required to incorporate powder. Scaling criteria are also suggested to maintain incorporation performance between different scales of mixing vessel. Multivariate regression modelling is used to determine which powder properties are most significant in determining how easily a powder is incorporated into concentrated suspensions.

Two industrial case studies are presented in this thesis. The first involves design and scale up of a continuous powder incorporation process to prepare base catalyst washcoat slurries. This study presents a detailed design for a manufacturing scale production process. The second case study considers a powder mixing process for the pre-treatment of support powders prior to their incorporation into slurry, comparing the efficiency and capability of three separate mixers for this duty.

Type of Work:

Thesis (Doctorates > Eng.D.)

Award Type:

Doctorates > Eng.D.

Supervisor(s):