Carbon Dioxide Reforming of Methane over Ni Supported SiO 2 : Influence of the Preparation Method on the Resulting Structural Properties and Catalytic Activity

摘要

Ni-C/SiO 2 and Ni-G/SiO 2 catalysts were prepared by a complexed-impregnation method using citric acid and glycine as complexing agents, respectively. Ni/SiO 2 was also prepared by the conventional incipient impregnation method. All the catalysts were comparatively tested for carbon dioxide reforming of methane (CDR) at P = 1.0 atm, T = 750 °C, CO 2 /CH 4 = 1.0, and GHSV = 60,000 mL·g ?1 ·h ?1 . The results showed that Ni-C/SiO 2 and Ni-G/SiO 2 exhibited better CDR performance, especially regarding stability, than Ni/SiO 2 . The conversions of CH 4 and CO 2 were kept constant above 82% and 87% after 20 h of reaction over Ni-C/SiO 2 and Ni-G/SiO 2 while they were decreased from 81% and 88% to 56% and 59%, respectively, over the Ni/SiO 2 . The characterization results of the catalysts before and after the reaction showed that the particle size and the distribution of Ni, as well as the interactions between Ni and the support were significantly influenced by the preparation method. As a result, an excellent resistance to the coking deposition and the anti-sintering of Ni was obtained over the Ni-C/SiO 2 and Ni-G/SiO 2 , leading to a highly active and stable CDR performance.