Production of hydrogen by methane dry reforming over ruthenium-nickel based catalysts deposited on Al2O3, MgAl2O4, and YSZ

In this work, monometallic (1 wt% of Ru or 5 wt% of Ni) and bimetallic catalysts (1 wt% Ru-5 wt.% Ni) deposited on alumina (AlO), magnesium aluminate spinel (MgAlO), and yttria-stabilized zirconia (YSZ) were prepared by wet impregnation. The synthesis method of MgAlO was optimized and a well crystallized phase with high specific surface area was obtained by using wet impregnation, as a simple and low cost route, at 800 °C for 2 h. The catalytic activity was compared at atmospheric pressure and 750 °C toward methane dry reforming (DRM) reaction with a molar ratio CH/CO = 1/1 and a Weight Hourly Space Velocity (WHSV) of 60.000 mL g.h. Catalytic activity classification was obtained as the following: Ni/MgAlO > Ru-Ni/AlO > Ru-Ni/MgAlO > Ru-Ni/YSZ > Ni/AlO > Ni/YSZ > Ru/AlO > Ru/YSZ » Ru/MgAlO. Between the different catalysts, 5 wt% Ni/MgAlO catalyst exhibited excellent catalytic activity for DRM. Furthermore, this catalyst was found to be very stable without any deactivation after 50 h under reacting mixture with a low carbon formation rate (3.58 mg/g/h). Such superior activity and stability of MgAlO supported Ni catalyst is consistent with characterization results from BET, XRD, TPR, CO-pulse chemisorption and CHNS analysis. It can be due to a strong interaction between Ni and MgAlO leading to the incorporation of Ni into the spinel lattice and the formation of oxygen vacancies offering a benefit for DRM reaction. Furthermore, it seems that the addition of ruthenium onto Ni/MgAlO decreases the interaction between Ni and the spinel leading to a decrease in the catalyst performance. On the other side, the addition of ruthenium on Ni/AlO leads to an increase in the catalyst stability and efficiency by inhibiting the formation of poorly active phase NiAlO already observed in TPR.