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

Abstract

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.

Review on Additive Manufacturing of Catalysts and Sorbents and the Potential for Process Intensification

“…The major reason why protocols are not widely applicable is the fact that the ability of a binderless body to be mechanically stable is determined by the cohesive strength of the powder, the degree of porosity required and the post-processing procedure. In addition, the required mechanical stability also depends on the intended application and the shape of the body (Akhtar et al, 2014;Besser et al, 2017;Xu et al, 2017;Kong et al, 2018). This complex interplay of factors demands for a large amount of research for every single application.…”

Lorentz force promoted charge separation in a hierarchical, bandgap tuned, and charge reversible NixMn(0.5−x)O photocatalyst for sulfamethoxazole degradation

“…Effective separation of catalysts from reactant/product mixtures is required to prevent secondary contamination and reuse catalysts for practical applications. Deposition of catalysts on supporting substrates using (i) binder-through (organic [16] and inorganic [17]) and (ii) binder-less (spray coating [18], hot pressing [19], in-situ growth [20], and electrophoretic [21]) methods, results in the masking of active sites, reducing the surface areas of catalysts. Magnetically-separable nano-sized catalysts, such as CeO 2 , C 3 N 4 , graphene oxide, CdZnS, ZnO, ZnFe 2 O 4 , and TiO 2 can potentially facilitate the separation while retaining the intrinsic activity and specific surface area [22][23][24][25][26].…”

Synthesis and Characterization of MIL–101 (Cr) Adsorbent Coating on Microchannel Walls for Water Adsorption Heat Pumps

“…Meanwhile, SiO 2 12 and Al 2 O 3 26 have been widely used as binders and are shown to be necessary for washcoating processes. Additives such as polyethylene glycol (PEG) are thought to improve adhesion; however, they can increase the viscosity of the slurry, which can complicate the coating process.…”

“…In contrast, for extrusion processes, where an external force is used to push the paste, the effect of marginal change on viscosity may not be significant. Yet, additives have been reported to increase the adsorbent loading and reduce the attrition compared to the process without additives. , The washcoating process typically also involves the addition of sacrificial or pore-forming agents to create void spaces, such as yeast . The sacrificial agents improve the diffusivity in the washcoat, hindering its mechanical strength.…”