Preparation of porous paper composites with ruthenium hydroxide and catalytic alcohol oxidation in a multiphase gas–liquid–solid reaction

• Flexible and porous paper-structured Ru(OH)x catalysts were prepared successfully.
• Ru(OH)x catalysts were dispersed on the ceramic fiber networks of paper composites.
• Catalytic oxidation of benzyl alcohol proceeded efficiently in three-phase reactions.
• Paper catalysts exhibited much higher performance than conventional solid catalysts.

In situ synthesis of ruthenium hydroxide catalysts on a microporous fiber-network structure of ceramic paper composites was achieved. The efficient catalytic oxidation of alcohol was investigated in a heterogeneous, multiphase gas–liquid–solid reaction. A simple papermaking technique and subsequent immersion in a ruthenium chloride solution allowed us to fabricate novel-concept microstructured catalysts. The paper-structured catalysts possess micropores ca. 30 μm in diameter with high porosity of ca. 90%. They exhibited much higher catalytic efficiency in the O2-mediated oxidation in toluene of benzyl alcohol to benzaldehyde in a fixed bed external loop reactor, as compared with conventional pellet- and bead-type solid catalysts. This excellent catalytic effect is possibly attributed to the porous paper composite microstructure like microreactors.