Hydrogen production through autothermal reforming of CH4: Efficiency and action mode of noble (M = Pt, Pd) and non-noble (M = Re, Mo, Sn) metal additives in the composition of Ni-M/Ce0.5Zr0.5O2/Al2O3 catalysts

Hydrogen production through autothermal reforming of methane (ATR of CH4) over promoted Ni catalysts was studied. The control of the ability to self-activation and activity of Ni-M/Ce0.5Zr0.5O2/Al2O3 catalysts was achieved by tuning their reducibility through the application of different types (M = Pt, Pd, Re, Mo or Sn) and content (molar ratio M/ Ni = 0.003, 0.01 or 0.03) of additive. The comparison of the efficiency and action mode of noble (M = Pt, Pd) and non-noble (M = Re, Mo, Sn) metal additives in the composition of NiM/Ce0.5Zr0.5O2/Al2O3 catalysts was performed using X-ray fluorescence analysis, N-2 adsorption, X-ray diffraction, high-resolution transmission electron microscopy, scanning electron microscopy, X-ray photoelectron spectroscopy, temperature-programmed reduction with hydrogen, and thermal analysis. The composition-characteristics-activity correlations were determined. It was shown that the introduction of a promoter does not affect the textural and structural properties of catalysts but influences their reducibility and performance in ATR of CH4. At the similar dispersion of NiO active component (11 2 nm), the Ni2+ reduction is intensified in the following order of additives: Mo < Sn < Re < Pd < Pt. It was found that for the activation of Ni and Ni-Sn catalysts before ATR of CH4 tests, the pre-reduction is required. On the contrary, the introduction of Pt, Pd and Re additives leads to the self-activation of catalysts under the reaction conditions and an increase of the H-2 yield due to the enhanced reducibility of Ni2+. The efficient and stable catalyst for hydrogen production has been developed: in ATR of CH4 at 850 degrees C over an optimum 10Ni-0.9Re/Ce0.5Zr0.5O2/Al2O3 catalyst the H-2 yield of 70% is attained. The designed catalyst has enhanced stability against oxidation and sintering of Ni active component as well as high resistance to coking. (C) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.