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 SiO2 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, H2-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 CO2/CH4 = 1:1 and 900 C, the CO2 and CH4 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 SiO2. The mechanism inves-tigation via in-situ DRIFTS disclosed that in the process of DRM reaction, consecutive decomposition of adsorbed CH4 molecule to CHx fractions and further to C species was the prerequisite to initiate the reaction and the presence of CO2 could accelerate the above process by forming bridged carbonyls as reaction intermediate.

Automated summary

In this study, waste granular silica gel was reused as a nickel-based catalyst support. The Ni/WGSG catalysts showed good performance in the dry reforming of methane (DRM) reaction, with the Ni/WGSG-2 catalyst exhibiting the highest activity. The catalysts also demonstrated good stability under different working conditions.