Effect of NiO supported SiO2 in high concentration of CO.

The effect of a nickel oxide supported silica oxide (NiO/SiO₂) catalyst on temperature programmed reduction (TPR) with 40% (v/v) carbon monoxide (CO) in nitrogen atmosphere as reductant agent was investigated. The conventional impregnation method was used to create the NiO/SiO₂ catalysts. The reduction characteristics of NiO to Ni were investigated up to 700 °C, followed by isothermal reduction. The TPR profile of 9% NiO/SiO₂ slightly shifted to lower temperature from 412 to 392 °C. Whereas the undoped NiO was reduced at a lower temperature of 387 °C. XRD diffractogram of the catalysts showed a complete reduction of NiO to Ni and have different intensities for each different loading of NiO catalyst on SiO₂ support. The TEM images indicated that the carbon nanotubes were deposited on the NiO surfaces indicating some chemical reactions occur on NiO. It was found that the addition of 3% of NiO on SiO₂ also exhibited a larger BET surface area (532.8 m²g⁻¹) and insignificant pore diameter (5.9-6.0 nm). Based on these results, it is interesting to note that the addition of a small amount of NiO to SiO₂ has a remarkable influence by reducing the temperature in the reduction process. The 9% NiO/SiO₂ was found sufficient could enhance the reducibility of NiO at a lower temperature. [ABSTRACT FROM AUTHOR]