Core@shell catalysts based on nickel phyllosilicates for dry reforming of methane: Effects of aging under hydrolysis conditions

A new method for synthesis of catalysts with core@shell architecture has been developed for syngas production via dry reforming of methane (DRM). This route is based on the confinement of Stöber particles (silica nanospheres) by nickel phyllosilicates and a layer-analogous decoration made of SiO₂ (shell). Dry reforming catalysts based on non-noble metals suffer from deactivation via sintering and coke formation. Core@shell structures offer a strategy to enhance stability and control metal dispersion. In this work, the Stöber particles were obtained and then nickel phyllosilicate was synthetized over them (NiPS); silica was deposited on the resulting material producing a decorated material (S0@NiPS) and the effect of its aging under hydrolysis conditions for 12, 24, 36 and 48 h was evaluated (S12, S24, S36 and S48@NiPS). It was possible to demonstrate the efficiency of the proposed structures, with reagent conversion above 90 %, good yield to syngas and no signs of deactivation in the catalytic test at 700°C (coking condition), for the S24@NiPS sample (reducible nickel content 8 % w/w). The superior activity of S24@NiPS is attributed to optimal Ni dispersion and shell structure, balancing accessibility and confinement. The order of activity obtained was: S24@NiPS > S12@NiPS > NiPS > S36@NiPS > S48@NiPS > S0@NiPS. The materials were characterized by XRD, TPR-H2, TPO-O2, TEM, EDS and TPSR-DRM. The modification of the hydrolysis time changed the properties of the catalysts: the shortest and longest times generated the less active catalysts. These findings offer a route to a coke-resistant catalysts for CO₂ valorization and methane upgrading.