Synthesis of early transition metal carbides and their application for the reforming of methane to synthesis gas

Abstract

The carbides synthesized were tested as catalysts for methane reforming with carbon dioxide (dry reforming), giving carbon monoxide and hydrogen (synthesis gas) as the main products; of the binary carbides, only molybdenum and tungsten were active and stable, displaying activities comparable to the supported noble metal catalysts. No carbon deposition was observed on post-catalytic carbide samples. The catalytic properties of transition metal carbides and nitrides have attracted much attention in recent years. Because the group VI transition metals are abundant and relatively cheap, it has been suggested that they can replace the scarce and expensive noble metals for a number of catalytic applications. This chapter discusses that further research has been carried out concerning the temperature programmed reduction (TPR) synthesis method pioneered by Boudart and co-workers. In the original work, methane was used as the gaseous carbon source. It can be shown that using ethane, as the carbon source, results in the formation of metal carbides with higher surface areas than those produced by TPR with methane. In the chapter, the use of carbide catalysts for the reforming of methane has been extended to include the group V metals, niobium and tantalum, and the results obtained are compared with molybdenum and tungsten. In addition, following the recent synthesis of high surface area ternary metal carbides, these materials have also been tested for the dry reforming of methane with carbon dioxide to ascertain if the ternary structures provide any synergistic effects.