Effect of support modification on the physicochemical properties of a NiPd/Al2O3 catalyst for the autothermal reforming of methane

Abstract

For the development of effective catalysts for the autothermal reforming of methane, the NiPd catalysts were synthesized based on modified aluminum oxide and their physicochemical properties were studied using X-ray diffraction analysis, low-temperature nitrogen adsorption, transmission electron microscopy, and temperature-programmed reduction with hydrogen. It was found that the variation of modifying components (CeO2, ZrO2, La2O3, Ce0.5Zr0.5O2, and La2O3/Ce0.5Zr0.5O2) and their concentrations (10–30 wt %) makes it possible to regulate the particle size of NiO, the composition of a Ni-containing phase (NiO, La2NiO4, NiAl2O4, or Ni-La-Al-O) and the redox properties of nickel ions. It was shown that the average particle size of NiO increased from 6.7 to 17.5 nm in the following order of supports: La2O3/Al2O3 < La2O3/Ce0.5Zr0.5O2/Al2O3 < Al2O3 < Ce0.5Zr0.5O2/Al2O3 < CeO2/Al2O3 < ZrO2/Al2O3. On the introduction of the modifying oxides CeO2 and ZrO2 into aluminum oxide, the fraction of nickel in the composition of NiAl2O4 decreased and, therefore, the fraction of difficult-to-reduce Ni2+ decreased. The addition of La2O3 and La2O3/Ce0.5Zr0.5O2 strengthened the interaction of nickel cations with the support up to the formation of Ni-La-Al-O and La2NiO4 phases and increased the fraction of difficult-to-reduce Ni2+ ions. The resulting NiPd catalysts are promising in the catalysis of the autothermal reforming of methane.