Abstract
Spin coating was evaluated as alternative deposition technique to the commonly used dip coating procedure for washcoat deposition on high-porosity metallic substrates. By using spin coating, the washcoating of metallic open cell foams with very high pore density (i.e., 580 μm in cell diameter) was finely controlled. Catalytic performances of samples prepared with conventional dip coating and spin coating were evaluated in CO catalytic combustion in air, using palladium as active phase and cerium oxide as carrier. The incipient wetness method was used to prepare catalytic powder, which was dispersed by means of an acid-free dispersing medium. After washcoating, deposited layers were evaluated by optical microscopy and adhesion test. In comparison to dip-coated samples, the use of spin coating demonstrated better performances from both catalytic and coating quality points of view, highlighting the possibility of the industrial adoption of these supports for process intensification in several catalytic applications.
Highlights
The development of structured reactors is a topic of growing interest in heterogeneous catalysis, as it represents one of the most promising solutions to overcome heat and mass transfer limitations of traditional structured catalysts
Catalytic performances of samples prepared with conventional dip coating and spin coating were evaluated in CO catalytic combustion in air, using palladium as active phase and cerium oxide as carrier
The bare carrier and the catalytic active powder were characterized in terms of surface area and Characterization pore volume
Summary
The development of structured reactors is a topic of growing interest in heterogeneous catalysis, as it represents one of the most promising solutions to overcome heat and mass transfer limitations of traditional structured catalysts. Honeycombs represent the state-of-the-art solution for environmental processes like gas-exhaust after-treatment applications. These supports are characterized by a regular geometry where the flow enters parallel duct channels. Open cell sponges are cellular materials characterized by a random geometry They are constituted by a network of fully interconnected solid struts and open pores that are permeable to flow. The flow is not segregated, and radial mixing is allowed These aspects yield higher pressure drops with respect to honeycombs, but at the same time higher mass transfer coefficients are obtained [2]. To enable the intensification of environmental processes and to allow the design of more compact catalytic reactors, Catalysts 2018, 8, 510; doi:10.3390/catal8110510 www.mdpi.com/journal/catalysts
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