2C Catalysts Research Articles

Carbon and oxygen atom mobility during activation of Mo 2C catalysts

Temperature-programmed desorption (TPD) and reduction (TPR) were used to study the activation of Mo 2C for ethylene hydrogenation at 298 K. Mo 2C can incorporate large amounts of oxygen, and since oxygen is a poison for the reaction, it must be removed from the surface to activate the catalyst. As oxygen is removed from the surface by evacuation or reduction, it is replenished by diffusion of oxygen from the bulk. Therefore, the equivalent of several monolayers must be removed to obtain an oxygen-free surface, although it is not necessary to remove all the bulk oxygen. Furthermore, the oxygen cannot be removed by evacuation or reduction without also removing a significant amount of bulk carbon. Although the initial activity of the catalyst for ethylene hydrogenation is independent of the amount of carbon removed, the rate of deactivation of the Mo 2C strongly depends on the extent of carbon removal. As more carbon is removed, the rate of deactivation increases and the shape of the activity-time curve (deactivation curve) changes from an exponential decay to a sigmoidal shape. TPR spectra of oxygen chemisorbed on the surface after two different activation procedures showed that the surface of the catalyst depends on the extent of carbon removal. As more carbon is removed from the Mo 2C, the oxygen is bound more tightly to the surface. This suggests that ethylene also might be bound more tightly on the carbon-deficient catalyst, which is consistent with the higher rate of deactivation.

Report on the catalytic activity of 6-heteropolymolybdates as potential Fischer-Tropsch synthesis catalysts

Unsupported and supported decomposition products of 6-heteropolymolybdates were tested as possible Fischer-Tropsch synthesis catalysts. Depending on the heteroatom, the activity changes significantly and the best supported catalysts have higher activity (based on total metal loading) than previously investigated MoO 2 and Mo 2C catalysts.

Catalysis by transition metal carbides: V. Kinetic measurements of hydrogenation of CO over TaC, TiC, and Mo 2C catalysts

Catalysis by transition metal carbides: V. Kinetic measurements of hydrogenation of CO over TaC, TiC, and Mo 2C catalysts