The Carburization of Transition Metal Molybdates (MxMoO4, M = Cu, Ni or Co) and the Generation of Highly Active Metal/Carbide Catalysts for CO2 Hydrogenation

Abstract:

A new approach has been tested for the preparation of metal/Mo<inf>2</inf>C catalysts using mixed-metal oxide molybdates as precursors. Synchrotron-based in situ time-resolved X-ray diffraction was used to study the reduction and carburization processes of Cu<inf>3</inf>(MoO<inf>4</inf>)<inf>2</inf>(OH)<inf>2</inf>, α-NiMoO<inf>4</inf> and CoMoO<inf>4</inf>•nH<inf>2</inf>O by thermal treatment under mixtures of hydrogen and methane. In all cases, the final product was β-Mo<inf>2</inf>C and a metal phase (Cu, Ni, or Co), but the transition sequence varied with the different metals, and it could be related to the reduction potential of the Cu²⁺, Ni²⁺ and Co²⁺ cations inside each molybdate. The synthesized Cu/Mo<inf>2</inf>C, Ni/Mo<inf>2</inf>C and Co/Mo<inf>2</inf>C catalysts were highly active for the hydrogenation of CO<inf>2</inf>. The metal/Mo<inf>2</inf>C systems exhibited large variations in the selectivity towards methanol, methane and C<inf>n</inf>H<inf>2n+2</inf> (n > 2) hydrocarbons depending on the nature of the supported metal and its ability to cleave C-O bonds. Cu/Mo<inf>2</inf>C displayed a high selectivity for CO and methanol production. Ni/Mo<inf>2</inf>C and Co/Mo<inf>2</inf>C were the most active catalysts for the activation and full decomposition of CO<inf>2</inf>, showing high selectivity for the production of methane (Ni case) and C<inf>n</inf>H<inf>2n+2</inf> (n > 2) hydrocarbons (Co case).

Año de publicación:

2015

Keywords:

• molybdenum oxide
• Molybdate
• Copper
• Molybdenum carbide
• CO hydrogenation 2
• nickel
• Cobalt
• CO2 hydrogenation

Fuente:

scopus

google