Mechanical Stability of Monolithic Catalysts: The Influence Mechanism of Primer on the Washcoat Adhesion to the Metallic Substrates

摘要

The mechanical stability of monolithic catalysts significantly impacts the performance of industrial monolithic reactors,because the washcoat layer usually shows bad adhesion to the substrate.In this paper,to obtain washcoated monolith with high mechanical stability,a modified method is chosen: A primer is introduced first and an alumina slurry coating is further washcoated on FeCrAl alloy foils.Advisable coating compositions are determined and it is found that the calcination of primer has an obviously bad influence on the washcoat adhesion property.Furthermore,the influence mechanism of primer on the washcoat adhesion is discussed.It is speculated that the cross-linkings between the alumina particles and PEG make the primer disperse homogeneously and connect tightly with the pretreated metallic substrate.When coating the second slurry layer,the dissolution of primer will narrow the gap between the primer and the slurry coating layer,which makes the particles at the primer-slurry interface connect together,and all of these are conductive to obtain homogeneous and tightness washcoat,showing good adhesion to the metallic substrate.