碳化钼催化剂加氢脱氮性能研究

Molybdenum carbide catalysts were prepared through temperatureprogrammed carburization of molybdenum trioxide with CH4/H2 gas mixture and characterized by XRD, BET, SEM, and XPS. The hydrodenitrogenation (HDN) performance of the molybdenum carbide catalyst was evaluated by using 5% pyridine/cyclohexane as a model reactant. The β-Mo2C prepared (carburized at 675℃) is in high purity with an average dimension of about 3.9 μm; its BET surface area is 10.7m2/g, which is 2.7 times higher than that of MoO3. Over Mo2C, pyridine HDN conversion reaches 86.30% under 340℃, 3.0MPa, and a space velocity 8h－1, which is about 8 percentages higher than that over MoS2. The optimal carburizing conditions for preparing Mo2C are around 675℃ with a CH4/H2 gas velocity of about 1.8×104h－1. Further increase of carburizing temperature may result in a decrease of the BET surface area of Mo2C and an increase of free carbon content deposited on the catalyst surface, which can then decrease the HDN activity of Mo2C.