Hydrogen production by autothermal reforming of methane: Effect of promoters (Pt, Pd, Re, Mo, Sn) on the performance of Ni/La2O3 catalysts

Abstract

We developed bimetallic catalysts Ni–Me/La2O3 (Me=Pt, Pd, Re, Mo, Sn) for hydrogen production by autothermal reforming of methane (ATR of CH4). The preparation procedure was based on the reduction of an appropriate LaNi1−xMexO3 (x=0.01–0.05) perovskite precursor obtained by the citrate sol–gel method. We investigated the effects of promoter type and molar ratio Me/Ni (Me=Pt, Pd, Re, Mo, Sn; Me/Ni=0.01–0.05) on the structural, reducing and catalytic properties of Ni–Me/La2O3 samples in the ATR of CH4 and systematically studied the genesis of catalysts by means of X-ray diffraction, thermogravimetric and differential thermal analysis, Ar adsorption, H2 temperature-programmed reduction, high-resolution transmission electron microscopy with energy-dispersive X-ray analysis, and X-ray photoelectron spectroscopy techniques. The genesis of the active phase is shown to be strongly affected by the promoter type. The Pt, Re, Mo or Sn promoters in contrast to Pd impede the destruction of LaNiO3 structure and formation of Ni0 phase. The catalytic performance of Ni–Me/La2O3 samples in the ATR of CH4 can be regulated by the type and content of the promoter. At low reaction temperatures (700–800°C) and at the molar ratio Me/Ni=0.01 the conversion of methane and product (H2, CO) yields increases in the following order of promoters: Pt<Sn<Mo<Re<Pd, which correlates with the increase of reducibility of Ni species as a result of promoter addition. At 850°C the LaNi0.99Pd0.01O3 catalyst provided the yields of ∼41% H2 and ∼57% CO at CH4 conversion ∼100% during a stability test that lasted 24h.