Pyrolysis of methane on oxide catalysts supported by resistive fechral and carborundum

Resumo

Catalysts on resistive supports, namely, on the thermally stable metal alloy fechral (FeCrAl) and carborundum (silicon carbide SiC) were studied in the pyrolysis of methane into acetylene. The active components chosen for deposition on carborundum were oxides corresponding to those present on the surface of the heat-treated fechral alloy: iron, chromium, and aluminum oxides, as well as zirconium and silicon oxides. The deposition of oxides on carborundum leads to an increase in methane conversion compared to the starting carborundum. The maximum acetylene selectivity was obtained using the ZrO₂/SiC and Al₂O₃/SiC catalysts. In contrast, the deposition of the same oxides on fechral leads to a decrease in the activity and acetylene selectivity compared with those of the starting heat-treated fechral. On the other hand, the deposition of oxides on fechral results in an increase in the temperature range of the catalyst operation and its stability over time. In the case of carborundum, the deposition of oxides does not affect these characteristics. The study of the starting supports fechral and carborundum and supports with metal oxides showed that high acetylene selectivity correlates with the formation of carbon fibers on the catalyst surface. These fibers mainly form on the surface of alumina, zirconia, and silica.