Design of Monolithic Supports by 3D Printing for Its Application in the Preferential Oxidation of CO (CO-PrOx)

Honeycomb-shaped cordierite monoliths are widely used as supports for a large number of industrial applications. However, the high manufacturing cost of cordierite monoliths only justifies its use for high temperatures and aggressive chemical environments, demanding applications where the economic benefit obtained exceeds the manufacturing costs. For low demanding applications, such as the preferential oxidation of CO (CO-PrOx), alternative materials can be proposed to reduce manufacturing costs. Polymeric monoliths would be an interesting low-cost alternative; however, the limitations of the active phase incorporation to the polymeric support must be overcome. In this work, the implementation and use of polymeric monolithic structures obtained by three-dimensional printing to support CuO/CeO2 catalysts for CO-PrOx have been studied. Several approaches were used to anchor the active phase into the polymeric monoliths, such as adding inorganic materials (carbon or silica) to the polymer previous to the printing process, chemical attack with solvents of the printed resin before or during the active phase incorporation, and consecutive impregnation and modification of the channel wall design. Among those approaches, best results were obtained by the addition of silica and by channel modification. Independent of the strategy followed, a subsequent thermal treatment in N2 was required to soften the resin and favor the active phase anchoring. However, catalyst particles become embedded on the polymeric resin being not active, and thus, a final cleaning thermal treatment under air was needed to recover the active phase activity, after which the supported active phase demonstrated good catalytic activity, stability, and reusability.