One-pot fabrication of waste granular silica gel (WGSG) supported nickel catalysts for dry reforming of methane

The waste granular silica gel (WGSG) was reused as nickel-based catalyst support, where the innovation could be reflected in the following aspects: recycling the SiO 2 resources to reduce catalyst cost and utilizing the granular shape to skip catalyst molding. The Ni/WGSG catalysts were prepared by a facile one-pot impregnation method and further tested in the dry reforming of methane (DRM) reaction. The physico-chemical properties of the catalysts were also characterized by XRD, H 2 -TPR, TGA, SEM and TEM. It was found that among the three catalysts with different Ni contents, the Ni/WGSG-2 with medium Ni loading amount showed a comprehensively better activity towards DRM. Under the condition of CO 2 /CH 4 = 1:1 and 900 °C, the CO 2 and CH 4 conversion of Ni/WGSG-2 catalyst could reach 83.6% and 69.5%, respectively, due to its better anti-coking and anti-sintering ability than the other two catalysts. The stability test with varying working conditions showed the Ni/WGSG-2 catalyst can function steadily for 30 h without large deactivation and its average activity is comparable to several Ni catalysts using complex substrates such as carbonized materials and core-shell SiO 2. The mechanism investigation via in-situ DRIFTS disclosed that in the process of DRM reaction, consecutive decomposition of adsorbed CH 4 molecule to CH x fractions and further to C species was the prerequisite to initiate the reaction and the presence of CO 2 could accelerate the above process by forming bridged carbonyls as reaction intermediate. ● The waste granular silica gel was reused as Ni-based catalyst support for DRM. ● The designed catalyst was prepared by a facile one-pot impregnation method. ● The as-prepared catalyst was directly in the sphere shape to skip molding process. ● The Ni/WGSG-2 catalyst worked stably for 30 h with relatively high activity.