Formulation of porous catalyst supports: formulation, manufacturing, testing and performance modelling

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Celani, Andrea (2019). Formulation of porous catalyst supports: formulation, manufacturing, testing and performance modelling. University of Birmingham. Eng.D.

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Abstract

Catalysts have a significant role in industry and the optimization of their performances could have significant impact in terms of environmental and economic aspects. In addition to the selected active species, catalyst performances are also influenced by the structural characteristics of the catalyst support which impacts diffusion into the catalysts. For this reason, in recent years there has been an increasing interest in the use of ceramic foams as catalysts supports.

In this work, new formulations of directly foamed ceramic suspensions were developed. These presented benefits in terms of both environmental impact and pH operating window. The performances of the new amphiphiles were tested and they were then ranked in accordance with their hydrophobicity. Correlations between amphiphile hydrophobicity and foam structure were found giving an insight on how to tailor the initial formulation to obtain the desired foam structure.

Foams structure is also affected by its manufacturing process. An aerated stirred vessel was used to generate the foam and a Design of Experiment was carried out to determine the process parameters that effects foam structure. Foam structure (e.g. porosity and bubble size) was correlated to global mixing parameters and mixing regimes to understand the mixing conditions necessary to obtain the desired foam. In addition, foams rheological properties were correlated to its bubble size and bubble size distribution; this correlation could result in the use of rheological measurements as an at-line technique to control the foam structure.

The performances of foam supported catalysts were tested in different reactions such as Fischer Tropsch and methane oxidation. In both cases foam supported catalyst gave better performances in respect to conventional ones. The improved performances were attributed to the lower diffusion resistance inside the catalyst particles.

To screen the performances of catalysts having different structures, a computational approach was used to simulate the methane oxidation reaction when foams with different porosities were used as supports. An in-house developed kinetic model was validated against experimental results acquired by SpaciMS technique. In addition, two different approaches (1D + 1D and CFD) were used to simulate the reaction in a monolithic reactor resulting in comparable profiles.

A 1D + 1D model was used to simulate the methane light-off curve and it was compared with the experimental results. The comparison showed that, upon selection of the right characterization technique to reconstruct the foam structure, it was possible to satisfactorily reproduce the experimental light-off curve. The developed model allows a faster screening of the performances of catalysts supported on ceramic foams having different structures resulting in a more economical and faster catalysts development.

Type of Work:

Thesis (Doctorates > Eng.D.)

Award Type:

Doctorates > Eng.D.

Supervisor(s):