Multiphase catalytic oxidation of alcohols over paper-structured catalysts with micrometer-size pores

• Flexible paper-like Ru(OH)x catalysts with micrometer-size pores were prepared.
• Paper catalysts exhibited much higher performance than solid bead catalysts.
• Residence time measurement revealed homogeneous liquid flow into paper composites.
• Catalytic oxidation proceeded on paper catalysts covered with thin liquid layers.

Paper-structured catalysts were prepared using ceramic fibers by a wet papermaking technique, followed by the deposition of ruthenium hydroxide on the fiber-network microstructures. As-prepared flexible paper catalysts possessed large geometric surface areas with micrometer-size pores. The paper-structured catalysts exhibited high catalytic efficiency for selective aerobic oxidation of aromatic and aliphatic alcohols to their corresponding aldehydes and ketones, in a fixed bed multiphase reactor. Hydrodynamic behavior in the reactor filled with either paper or bead catalysts was evaluated by measuring the residence time distribution in a cold flow model. It was revealed that the paper composites exhibited good wettability and internal diffusion of liquid substances compared with ceramic beads, showing heterogeneous liquid flow. Efficient catalytic oxidation of various alcohols was achieved using the paper-structured catalysts because uniform fluid dynamic behavior formed a thin liquid layer on the catalyst surfaces, possibly resulting in favorable gas–liquid–solid interfaces.

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