A Comprehensive Study of the Washcoating of MCM-41 on Stainless Steel Tubular Microreactors

A method for washcoating of MCM-41 onto the internal surface of a stainless steel tubular microreactor was developed. The suspension was prepared with polyvinyl alcohol, milled MCM-41, colloidal silica, water, and acetic acid, with mass percentage of x₁, x₂, x₃, x₄ and x₅, respectively. The effect of the slurry composition on the characteristics of the coating (adhesion, thickness and loading) was identified by a statistical mixture design; values of x₁, x₂, x₃ and x₄ were varied and x₅ was fixed in 1.0 wt.%. The thickness and homogeneity of the coating in the microreactor were evaluated by SEM, while loading and adhesion were gravimetrically estimated. In the cases, a good adherence layer was found. The statistical methodology of mixture D-Optimal type showed that the component of the suspension with the highest effect on the coating properties was PVA. Thickness (22 ± 5 µm) and loading (2.59 mg/cm²) of the coating were optimized with the criteria of a minimum thickness with a maximum possible loading due to the need to find the right combination to increase microreactor efficiency in applications such as catalysis. The optimal composition of the suspension obtained by statistical analysis was PVA (1.9 wt.%), MCM-41 (15.2 wt.%), colloidal silica (5.0 wt.%) and water (76.9 wt.%).