Abstract: Controllable synthesis of the silica-supported rhodium catalyst with uniform particle size has been achieved through microemulsion technique by manipulating the W0 value (molar ratio of water to surfactant in the precursor). The catalyst shows a core-shell morphology, in which rhodium is encapsulated by a silica shell. The characterization of the catalyst morphology by TEM and the catalytic performance of the catalyst for CO hydrogenation indicated significant influence of the rhodium particle size. There was a minimum value of the CO conversion over the catalyst with the average rhodium particle size of 3 nm in the range of 1.8～5.0 nm. With increasing the rhodium particle size from 3 to 5.0 nm, the reactivity increased. Compared with the Rh/SiO2 catalyst prepared by the conventional impregnation method, the present catalyst had more uniform distribution of rhodium particle size and showed superior catalytic activity for CO hydrogenation, when the catalyst samples had the same loading and average particle size.

Key words: carbon monoxide, hydrogenation, rhodium, silica, supported catalyst, particle size, microemulsion method