Ni-modified alumina-supported 0.4 wt.% Pd catalysts with NiO
loading varying among 0.0, 0.5, 1.0, and 9.0 wt.% were investigated
for low-temperature CH4 combustion under fuel-lean conditions.
When the c-Al2O3 support was modified by nickel and calcined
at a high temperature, a spinel NiAl2O4 complex oxide formed over
the surface, and its amount increased with an increase in NiO loading
amount from 0.5 to 9.0 wt.%. The interaction between the
NiAl2O4 spinel interface and PdO favored the distribution of the
PdO component, and the formation of well-crystallized PdO, suppressed
the PdO particles’ aggregation and surface OH species
accumulation during the reaction, and finally led to the excellent
performance of Pd/0.5NiO/c-Al2O3, with higher Pd utilization efficiency than the state-of-the-art Pd-based catalysts and better reaction
stability than Pd/c-Al2O3, while further increasing the spinel
NiAl2O4 amount led to poorer activity of the modified catalysts
due to greater PdO particle size, lower BET area, and poorer interaction
between the spinel NiAl2O4 (or inert bulk property of NiAl2-
O4) and PdO. In all, the formation of a spinel NiAl2O4 interface over
industrially relevant high-surface-area Al2O3 support paves the
way to develop more efficient use of noble metals as catalysts.