The promotion effect of Ru on catalytic activity and stability of Ni/Co-Al2O3 catalysts for simulated diesel steam reforming

[Display omitted] •Incorporating Ru improves the catalytic capability and durability of both Ni and Co catalysts.•Ru modification decreases the dehydrogenation barriers of CHx* on the NiRu metal surface.•Ru-doped Co catalysts alter the main intermediates for CH4 dehydrogenation and hence enhance carbon resistance. In this work, Ru is incorporated into Ni/Co to synthesize novel Al2O3-supported Ni-Ru/Co-Ru bimetallic catalysts. Tests verify their enhanced catalytic capability and durability and also reveal how each catalyst is deactivated. SEM and EDS results indicate that nanoparticle agglomeration on Ni-based surface triggers deactivation, and TG and XPS results suggest carbon deposition is fatal to Co-based catalysts. Implementing Ru effectively enhances catalytic activity and durability. To gain insight into the promoting effect of Ru, quantum mechanical methods are utilized to investigate the shifts in activation energies (Ea) in CHx* dehydrogenation processes on (111) surfaces. For the Ni catalyst, DFT calculations indicate that adding Ru decreases Ea yet does not change the determining step. In contrast, adding Ru on the Co surface changes the major intermediates from CH* to CH2*, which inhibits further dehydrogenation, and hence mitigates carbon deposition to preserve the catalytic activity of the surface.