Study of the preparation and catalytic performance of molybdenum carbide catalysts prepared with C2H2/H2 carburizing mixture

A series of molybdenum carbide catalysts were prepared using 10% C2H2/H-2 to carburize molybdenum trioxide at different temperatures. Their catalytic performance was evaluated using methane partial oxidation to synthesis gas as the model reaction. The structure of the catalysts treated under various conditions was characterized using X-ray diffraction, laser Raman spectroscopy, and scanning electron microscopy. The results show that MoO3 is first converted into MoO2 and MoC1-x. With the rise of the carburization temperature, MoO2 is converted into MoC1-x and the catalyst crystallites tend to be very small. However, the catalyst surface remains coated by MoO3 or MoO2. When the carbides are heated in N-2 to 850degreesC, they are converted into MoC1-x and beta-Mo2C. Interestingly, all the catalyst samples show high CH4 conversion and CO selectivity in partial oxidation of methane, although the pretreatment has some effect on the preliminary activity and selectivity. The catalyst is partly oxidized and there is a small amount of carbon deposition after the activity test. Acetylene is therefore a good carburizing agent for preparing molybdenum carbide catalyst at low temperature for the partial oxidation of methane. (C) 2002 Elsevier Science (USA).