Catalytic performance of Pd–NiCo2O4/SiO2 in lean methane combustion at low temperature

In this paper, the catalyst of Pd–NiCo 2 O 4 /SiO 2 was prepared and applied to the catalytic combustion of lean methane. Pd and NiCo 2 O 4 nanoparticles were uniformly distributed on the SiO 2 support, so that every Pd or NiCo 2 O 4 nanoparticle was separated from each other by another component. Comparing with Co 3 O 4 /SiO 2 , NiCo 2 O 4 /SiO 2 , Pd–Co 3 O 4 /SiO 2 and Pd#NiCo 2 O 4 /SiO 2 (catalysts without uniform distribution of Pd and NiCo 2 O 4 nanoparticles), Pd–NiCo 2 O 4 /SiO 2 had the highest catalytic activity in the catalytic combustion of lean methane, with a methane total conversion temperature at 378 °C. In addition, the high activity did not decrease during the long time reaction, which showed good thermal stability . TEM and BET results showed that the nanoparticle sizes of Pd and NiCo 2 O 4 were very small. The XRD patterns indicated that the Pd nanoparticles were highly dispersed on the surface of SiO 2 . The XPS spectra demonstrated the formation of NiCO 2 O 4 , the presence of enough active oxygen species on the catalyst surface and the high ratio of PdO/Pd 0 . The enhanced influence of Ni introduction was also proved by comparison tests. All these results indicated that the high catalytic activity of Pd–NiCo 2 O 4 /SiO 2 mainly comes from the nanoparticle distribution and the Ni cation enhancement.