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

Abstract

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 Mo 2 C 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 Mo 2 C catalysts obtained.

Task‐Specific Catalyst Development for Lignin‐First Biorefinery toward Hemicellulose Retention or Feedstock Extension

“…[19] Different temperatureso f6 00, 700, and 800 8Cw ere used to tailor the catalyst properties. [19] Different temperatureso f6 00, 700, and 800 8Cw ere used to tailor the catalyst properties.…”

A general and scalable synthesis approach to porous graphene

“…Carbothermal reactions are thermal reactions that use carbon as the reducing agent at high temperature [29][30][31] , in which most metal oxide could be reduced into metal and metal carbide accompanying with the carbon atom leaving in the form of carbon monoxide and carbon dioxide 32 . The most prominent example is that of iron ore smelting, which is used in the production of iron or steel.…”

A novel approach to the synthesis of bulk and supported β-Mo2C using dimethyl ether as a carbon source

“…19,20 Among these preparation routes, the most promising and widely used one is the gas-phase carburization of molybdenum oxides. 19,21 With the increase of carbon materials as promising supports in many Mo 2 C-related catalyst systems, 13,[26][27][28][29] another strategy was to develop a carbothermal (hydrogen) reaction method with carbon support (e.g. 21 To our knowledge, there are many gas-state carbon sources, such as alkanes (CH 4 , C 2 H 6 , C 3 H 8 and C 4 H 10 ), 19,21-23 alkene (C 4 H 8 ) 24 and alkyne (C 2 H 2 ), 25 for the carburization reaction route.…”

“…In general, this route can be divided into a temperatureprogrammed reduction (TPR) method and a rapid heating (RH) method on the basis of the heating procedure, and it has become apparent that different heating conditions bestow various microstructure properties on the resulting carbides. activated carbon, 30,31 carbon black 13,31 and carbon nanotube 13,27,31 ) functioning as a solid-state carbon source for the synthesis of carbide. However, a problem has been found in the route, in which excess polymeric carbon from the pyrolysis of the carbonaceous gases at relatively low temperatures can deposit on the surface of the resultant carbide.…”