摘要
Ni/SiO2-ZrO2 catalysts with Ni loadings of 1 to 13 wt-% were prepared, characterized by elemental analysis, X-ray diffraction, N2 sorption, temperature programmed oxidation, temperature programmed reduc- tion, and tested for their activity and stability in the dry reforming of methane with carbon dioxide at 850 ℃, gas hourly space velocity of 6000 and 1800 h^-1 and atmo- spheric pressure. The SiO2-ZrO2 support as obtained through a simple and efficient sol-gel synthesis is highly porous （ABET = 90 m^·g^-1, dp= 4.4 nm） with a homogeneously distributed Si-content of 3 wt-%. No loss of Si or formation ofmonoclinic ZrO2, even after steaming at 850 ℃ for 160 h, was detectable. The catalyst with 5 wt-% Ni loading in its fully reduced state is stable over 15 h on-stream in the dry reforming reaction. If the catalyst was not fully reduced, a reduction during the early stages of dry reforming is accompanied by the deposition of up to 44 mg· g^-1 carbon as shown by experiments in a magnetic suspension balance. Rapid coking occurs for increased residence times and times-on-stream starting at 50 h. The Ni loading of 5 wt-% on SiO2-ZrO2 was shown to provide an optimal balance between activity and coking tendency.
Ni/SiO2-ZrO2 catalysts with Ni loadings of 1 to 13 wt-% were prepared, characterized by elemental analysis, X-ray diffraction, N2 sorption, temperature programmed oxidation, temperature programmed reduc- tion, and tested for their activity and stability in the dry reforming of methane with carbon dioxide at 850 ℃, gas hourly space velocity of 6000 and 1800 h^-1 and atmo- spheric pressure. The SiO2-ZrO2 support as obtained through a simple and efficient sol-gel synthesis is highly porous （ABET = 90 m^·g^-1, dp= 4.4 nm） with a homogeneously distributed Si-content of 3 wt-%. No loss of Si or formation ofmonoclinic ZrO2, even after steaming at 850 ℃ for 160 h, was detectable. The catalyst with 5 wt-% Ni loading in its fully reduced state is stable over 15 h on-stream in the dry reforming reaction. If the catalyst was not fully reduced, a reduction during the early stages of dry reforming is accompanied by the deposition of up to 44 mg· g^-1 carbon as shown by experiments in a magnetic suspension balance. Rapid coking occurs for increased residence times and times-on-stream starting at 50 h. The Ni loading of 5 wt-% on SiO2-ZrO2 was shown to provide an optimal balance between activity and coking tendency.
