Microfibrous-Structured Pd/AlOOH/Al-Fiber with Hydroxyl-Enriched Surfaces for the Catalytic Semihydrogenation of Acetylene

Thin-sheet Al-fiber-felt-structured Pd/AlOOH/Al-fiber catalysts are developed for the back-end process of semihydrogenation of acetylene. A series of AlOOH/Al-fiber substrates were synthesized by endogenous growth and subsequent annealing in air. Palladium was then dispersed onto the as-obtained substrates by impregnation. The catalyst activity and stability show interesting substrate annealing temperature dependence. The preferred catalyst, obtained by dispersing lower than 0.05 wt % Pd onto the AlOOH/Al-fiber annealed at 100 °C, exhibits a high specific activity with the turnover frequency (measured at 40 °C) of 0.0167 s^-1, being two times as high as that (0.0083 s^-1) for the catalyst using a high substrate annealing temperature of 600 °C. Low AlOOH/Al-fiber annealing temperature enables the catalysts with hydroxyl-rich surfaces that not only promote the hydrogen activation on Pd but also strengthen the adsorption of acetylene. Notably, the Pd-hydroxyl interaction obviously suppresses carbonaceous deposition, thereby getting the stability improved by a large extent.