Development of a centrifugal coating method to load catalyst washcoat onto porous substrates with high uniformity and adhesive strength

Porous metal-based substrates with high porosity and surface/volume ratio have been widely used in microreactors for enhancing heat and mass transfer, while the generally poor uniformity and low adhesive strength of catalyst coating onto these porous substrates will limit the performance and service life of microreactors. Herein, we present a rapid centrifugal coating method to effectively and uniformly load γ-Al2O3 washcoat onto porous copper foam, which can be used to fabricate structured γ-Al2O3/Cu foam supports. The structural design of the centrifugal coating device and its coating loading mechanism are described. Hydroxyethyl methyl cellulose (HEMC) was used as the binder and its effects on the loading capacity and adhesive strength of γ-Al2O3 washcoat were studied. Then, the effects of loading parameters of the centrifugal coating process were carried out, and the relatively uniform γ-Al2O3 washcoat on the porous copper foams with different pores per inch (PPI) were obtained. The surface morphology, specific area, composition, and element distributions of the activated washcoat were characterized by using SEM, BET, XRD, and EDS, respectively. Results showed that the catalyst coating generally has a high specific surface area and uniform elements distribution, thus demonstrating our developed rapid centrifugal coating method has potential for the preparation of catalyst coating onto porous metal-based substrates in microreactors.