Simple and large-scale synthesis of β-phase molybdenum carbides as highly stable catalysts for dry reforming of methane†
Abstract
In this work, we propose a facile, fast and large-scale synthesis of β-Mo2C catalysts (about 100 grams). The current approach uses a simple solid mixture of (NH4)6Mo7O24·4H2O and carbon nanotubes (CNTs) as a precursor and employs a fast heating rate method without holding time. Moreover, there was no need for passivating the carbide products. A series of β-Mo2C/CNT catalysts (denoted as MoC-5, -15, -30 and -60) were successfully prepared from the precursors with the Mo content ranging from 5 to 60 wt% and their catalytic activities for dry reforming of methane (DRM) were evaluated. CH4-TPSR and CO2-TPO over the fresh samples proved that the abilities of CH4 dissociation and oxidation resistance of β-Mo2C were greatly enhanced by compositing with CNTs. It was also found that these abilities were dependent on the Mo content, the particle size and the interaction between β-Mo2C and CNTs. Among these β-Mo2C/CNT catalysts, MoC-30 showed the best catalytic stability for DRM, attributed to its high activity for CH4 dissociation and high resistance to oxidation. Additionally, it is worth noting that the catalytic stability of monometallic MoC-30 was found to be superior to that of bimetallic Ni/β-Mo2C (recently known to be an efficient non-noble metal catalyst for DRM).