Controllable preparation and catalytic performance of Pd/anodic alumina oxide@Al catalyst for hydrogenation of ethylanthraquinone

• θ-ring AAO@Al with different pore sizes and depths of AAO was controllable prepared.
• Due to the confinement effect, Pd/AAO@Al catalysts exhibited high metal dispersion.
• The throughout pores of the θ-ring catalysts showed advantages in mass transfer.
• The H2O2 yield of AAO catalyst is twice than that of spherical Pd/Al2O3 catalyst.
• AAO@Al with 24.5 nm pore size and 18 μm depth has shown the best catalytic performance.

Anodic alumina oxide (AAO) supports with different pore sizes and depths were controllable prepared by a two-step low-potential anodizing process. The prepared AAO supports with θ-ring shape were utilized to prepare supported Pd catalysts by impregnation method for the first time. The catalytic performance of the Pd/AAO@Al catalysts were investigated in the catalytic hydrogenation of 2-ethylanthraquinone (eAQ) to 2-ethylanthrahydroquinone, a key step in the anthraquinone process for the manufacture of hydrogen peroxide. Compared with Pd supported on spherical Al2O3 catalyst, Pd/AAO@Al catalysts showed much higher anthraquinone hydrogenation activity and preferable selectivity due to the highly ordered array of cylindrical shaped pores, short diffusion distance and confinement effect of the AAO supports. Furthermore, the effect of pore size and depth to the catalytic performance towards hydrogenation of eAQ has also been studied. Pd nanoparticles supported on AAO support with 24.5 nm pore size and 18 μm depth exhibited the best catalytic performance towards hydrogenation of eAQ.

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