Temperature profile of catalyst bed during oxidative steam reforming of methane over Pt-Ni bimetallic catalysts

The catalyst bed temperature during oxidative reforming of methane (CH₄/H₂O/O₂/Ar = 40/30/20/10) at 1123 K and atmospheric pressure was investigated by infrared thermography over γ-Al₂O₃ supported bimetallic Pt-Ni catalysts prepared by different impregnation methods: co-impregnation and sequential impregnation. The thermographical results clearly demonstrated that the catalyst bed temperature was strongly dependent on the preparation method. The bimetallic catalyst prepared from the sequential impregnation method exhibited much higher resistance to hot spot formation in oxidative reforming of methane. Temperature programmed reduction (TPR) with H₂ revealed that the addition of Pt by a sequential impregnation method greatly promoted the reduction of Ni species; furthermore, infrared spectra of CO adsorption suggests that the surface composition of Pt on the catalyst prepared by the sequential method is much higher than that for the catalyst prepared by the co-impregnation method. The surface enrichment of Pt is responsible for the effective overlap between the combustion and reforming zones, and this can enhance the inhibition of hot spot formation.