ИСТИНА

Fischer-Tropsch synthesis (FTS) is an industrial-scale process to obtain synthetic hydrocarbons via catalytic hydrogenation of carbon monoxide over cobalt or iron based catalysts. The present study is devoted to the properties of carbon nanotubes (CNTS) as a support for Co-catalysts in FTS. Traditional oxide supports for FTS catalysts possess well-known disadvantages such as low thermal conductivity and reactivity to the active metals, which, respectively, causes local overheating and decreases reaction rate. CNTs provide both the high dispersion of metal nanoparticles and the uniform heat distribution over catalyst bulk, so this material is promising for the application in FTS. At the same time, carbon surface itself cannot effectively stabilize cobalt particles; therefore functionalization is used to provide active centers for metal anchoring. In this work we consider the nitric acid treatment of CNTs and its effect on the Co/CNT catalytic activity, selectivity, and stability. One of the main drawbacks of oxidized carbon supports is low thermal stability of the surface functional groups. We found that only about 25% of the initial oxygen remained on the support surface after catalyst synthesis, activation and FTS tests for 70 h [1]. Structural transformations of the CNT surface were studied by nitrogen adsorption, TEM, and Raman spectroscopy. As the etching of the material under hydrogen atmosphere was observed we proposed soft regeneration for such systems. This regeneration includes air oxidation and reduction stages that were chosen based on the results of thermal analysis.