TiO2-modified bentonite as a cost-effective support for nickel-based catalysts in dry reforming of methane

The potential of TiO₂-modified bentonite as a cost-effective support for nickel-based catalysts in the dry reforming of methane (DRM) is highlighted. The comparison of a nickel catalyst supported on natural bentonite and one prepared on TiO₂-modified bentonite revealed a significantly different behavior between the two catalysts under diluted and concentrated DRM reaction conditions. The unmodified bentonite catalyst, 15Ni/Na-Bent, exhibits high activity under diluted conditions (20CH₄:20CO₂:60He) but deactivates quickly under concentrated DRM conditions (40CH₄:40CO₂:20He). On the other hand, 15Ni/TiO₂-Bent is less active at diluted conditions but demonstrates superior stability and activity in concentrated conditions. In situ XPS analysis of the O 1s, Al 2p, Si 2p, and Ti 2p regions of the calcined, reduced, and post-DRM samples revealed that TiO₂ stabilizes the clay structure and prevents nickel reoxidation. The formation of TiO_2-x species after reduction creates oxygen vacancies that trap oxidizing species in the reaction medium, thus limiting nickel reoxidation and reducing carbon deposition on the surface. Moreover, these TiO_2-x species migrate to the nickel surface, forming a thin protective layer that partially encapsulates the nickel, improving metal–support interactions and providing resistance against sintering and reoxidation. In addition to XPS spectroscopy, which provided insights into the nature of the metal–support interactions in the 15Ni/Na-Bent and 15Ni/TiO₂-Bent catalysts, the materials were also characterized using XRF, XRD, SEM, BET, TPR-H₂, and Raman spectroscopy. These techniques offered complementary structural, textural, and morphological information, leading to a more comprehensive understanding of the catalysts’ physicochemical properties.