Influence of carbon monoxide as reducing agent on carburization of molybdenum trioxide.

Temperature programmed reduction (TPR) analysis was used to evaluate the chemical reduction progression and carburization behavior of a molybdenum oxide (MoO₃) catalyst utilizing carbon monoxide (CO) as a reductant. X-ray diffraction spectroscopy (XRD), transmission electron microscopy (TEM), and a CHNS/O elemental analyzer were used to determine the composition and morphology of the reduced phases. The reduction and carburization behaviour of MoO₃ catalyst was attained up to 700 °C in a stream of 60 vol. % CO in helium. Carburization was continued with isothermal mode at 700 °C for 90 and 120 min. XRD analysis confirmed the formation of molybdenum carbide (Mo₂C) at 2θ=34.49° and 61.63° after carburization for 90 min at 700°C. After prolonged the carburization process for 120 min, XRD patterns shows the increasing in intensity of Mo₂C peak at 2θ=34.58°, 61.67° and 74.48°. This is consistent with the CHNS/O data which show the increasing in carbon contents from 9.8 % to 11.0 % when isothermal mode of carburization was increase from 90 min to 120 min. The TEM analysis shows the sample was surrounded by less dark layer which expecting the formation of carbon after 90 min carburization. While for carburization up to 120 min, the TEM image shows the clump densely particles against each other so that no pores are present. Hence, the CO as reducing agent able to promote the formation of Mo₂C while the increasing in carburization times able to enhance the formation of carbide species. [ABSTRACT FROM AUTHOR]