Influence of alumina binders on adhesion and cohesion during preparation of Cu-SAPO-34/monolith catalysts

The adhesion and cohesion between the coating layers and the ceramic honeycombs are usually one of the key issues in the preparation of high-performance zeolite-based/Monolith catalysts. In this work, we investigate the deposition of high-efficiency Cu-SAPO-34 catalyst on a cordierite monolith with special focus on the impact of alumina binders on the structure, mechanical adhesion and cohesion, and catalytic performance of the monolithic catalyst. Two kinds of alumina nanoparticles, α-alumina and γ-alumina, have no significant impacts on the Cu-SAPO-34 crystal structure, micropore morphology and catalytic activity. But washcoating experiments showed that the mass loss rate of the coating was less and the loading of the catalyst was higher when α-alumina was used as the binder. The reason of improving the adhesion and cohesion strength is the suitable thermal shrinkage, the uniform distribution and densification structure of α-alumina. Furthermore, optimization of the coating formulation with α-alumina as the binder has been performed. Finally, the catalyst prepared under the optimal conditions was tested by SCR and a maximum conversion rate of 97.4% was obtained. It was concluded that the use of the washcoating method with α-alumina does not affect catalytic performance while it increases bonding strength between substrate and catalysts.