Fabrication of molybdenum carbide catalysts over multi-walled carbon nanotubes by carbothermal hydrogen reduction

摘要

Molybdenum carbide catalysts were successfully prepared using original multi-walled carbon nanotubes (MWCNTs) and nitric acid treated ones as support and carbon source by carbothermal hydrogen reduction from 580 °C to 700 °C. Ammonium heptamolybdate was used as Mo precursor and the effects of oxygen functional groups on MWCNT surface were investigated. TEM and XRD results show that oxygen functional groups act as anchor sites to interact with the Mo oxyanion species during impregnation, which promote the dispersion of Mo precursors. Due to the relatively strong interaction between Mo precursors and MWCNTs, the agglomeration of Mo carbide particles is prevented even when the treatment temperature is as high as 700 °C. Moreover, as the support, modified MWCNTs exhibit better thermal resistances. The temperature (580 °C) for Mo2C formation over MWCNTs is much lower than that over conventional carbon supports using carbothermal hydrogen reduction. The methylcyclohexane dehydrogenation was used as a probe reaction to test the catalytic performances of the Mo2C catalysts obtained.