Study of unsupported and active carbon supported β-Mo 2C prepared from MoCl 5 precursor

Abstract

We have studied the preparation of unsupported and lignite supported β-Mo 2C using MoCl 5 as precursor. The catalysts were characterized by XRD and TEM techniques and tested in the reaction of propene hydrogenation at room temperature and pressure. Total carburization was observed at 923 K and although incomplete, carburization also occurred at 473 or 723 K. The high temperature supported carbide exhibited a remarkable lifetime in the test reaction (72 h), whereas, the massive carbide rapidly deactivated (<1 h). The low temperature carburized catalysts also rapidly deactivated (10 min). However, in a remarkable way, processing of the used catalysts by H 2 at 723 or 873 K, not only restored the initial activity, but increased their stability with time on stream (3 and >24 h, respectively). The correlation between the degree of carburization, dispersion and catalyst stability is discussed.