Cobalt-modified mesoporous FSM-16 silica: Characterization and catalytic study

Mesoporous FSM-16 silica has been synthesized and modified by impregnation with 3, 6 and 9 wt% Co. The powder X-ray diffraction and N2 sorption characterizations show that the resultant materials have well-ordered hexagonal mesoporous-structures. BET surface areas, pore volumes and pore diameters are decreased as the cobalt loading increases, also d-spacing (1 0 0) is shifted to a lower value. According to temperature programmed reduction, three hydrogen consumption peaks are detected, the first was formed probably due to the reduction of Co3O4 to CoO, the second to reduction of CoO to Co and the third to interaction of cobalt species with the silica of FSM-16 forming cobalt silicate and hydrosilicate. In infrared spectra, bands at 2356, 1637, 958, 800, 665 and 620 cm−1 are greatly affected by the cobalt loading. Methanol is completely dehydrogenated to formaldehyde in presence of 3 wt% Co/FSM-16 catalyst, whereas 9 wt% Co/FSM-16 one gives ethylene only due to methanol dehydration. The estimated regression equation is adequate and gives results in agreement with the experimental ones.