Physico-chemical characterization of shaped mesoporous silica prepared by pseudomorphic transformation as catalyst support in methane steam reforming

In this work, pseudomorphic transformation is introduced as an effective method to prepare mesoporous silica in the shape of millimeter sized disc from a biosilica precursor. The samples were prepared by two approaches. In the former method, pre-shaped silica discs were autoclaved in a basic solution containing cethyltrimethyl ammonium bromide (CTAB) and trimethyl benzene (TMB) to perform pseudomorphic transformation (S1) and in the latter case, silica powders were initially transformed by a pseudomorphic reaction following by shaping them before the removal of CTAB and TMB in calcination and sintering step (S2). The textural properties of the obtained mesoporous silica discs present that S2 sample results in larger pore size and also higher pore volume. The prepared samples have been utilized for preparation of Ni impregnated-silica catalysts in steam reforming of methane. Ni/S2 sample has been shown superior catalytic activity in comparison with other samples (methane conversion of 75% and hydrogen yields more than 40% at 550 °C). The measured physicochemical properties of the samples have been implemented to describe the catalytic results and possible coking mechanism on different samples.