Low-temperature synthesis of α-alumina nanosheets on microfibrous-structured Al-fibers for Pd-catalyzed CO oxidative coupling to dimethyl oxalate

International audienceWe reported the low-temperature synthesis of -Al2O3 nanosheets on the microfibrous-structured Alfibers at 800 º C. The boehmite (AlOOH) nanosheets were initially formed on the Al-fibers through in situ endogenous growth. Then the AlOOH/Al-fibers was transformed to the -Al2O3/Al-fibers composite at 800 º C by a single heating step. The low-temperature phase transformation was tentatively attributed to the Al metal in the AlOOH/Al-fibers. Palladium was then dispersed on the -Al2O3/Alfibers composite, and the resulting Pd/-Al2O3/Al-fibers catalyst was examined in the strongly exothermic CO oxidative coupling to dimethyl oxalate (DMO) reaction. High CO conversion of 58 % and DMO selectivity of 95 % were obtained and maintained for at least 150 h using a feedgas of CH3ONO / CO / N2 (1 / 1.4 / 7.6, mole) at 150 º C with a gas hourly space velocity of 20000 mL g 1 h 1. Computational fluid dynamics calculations and experimental results indicated that the Pd/-Al2O3/Al-fibers catalyst remarkably decreased the hot-spot temperature of catalyst bed due to its enhanced thermal conductivity