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 (Al2O3), magnesium aluminate spinel (MgAl2O4), and yttria-stabilized zirconia (YSZ) were prepared by wet impregnation. The synthesis method of MgAl2O4 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 degrees C for 2 h. The catalytic activity was compared at atmospheric pressure and 750 degrees C toward methane dry reforming (DRM) reaction with a molar ratio CH4/CO2 = 1/1 and a Weight Hourly Space Velocity (WHSV) of 60.000 mL g(-1). h(-1). Catalytic activity classification was obtained as the following: Ni/Al2O4 > Ru-Ni/Al2O3 > Ru-Ni/Al2O4 > Ru-Ni/YSZ > Ni/Al2O3 > Ni/YSZ > Ru/Al2O3 > Ru/YSZ a Ru/MgAl2O4. Between the different catalysts, 5 wt% Ni/MgAl2O4 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(c)/g(cat)/h). Such superior activity and stability of Al2O4 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 MgAl2O4 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/Al2O4 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/Al2O3 leads to an increase in the catalyst stability and efficiency by inhibiting the formation of poorly active phase NiAl2O4 already observed in TPR. (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.