Application of Ti-doped MoO2 microspheres prepared by spray pyrolysis to partial oxidation of n-dodecane.

The present investigation is focused on improving the performance of molybdenum dioxide (MoO 2 ) by doping with Ti for the partial oxidation (POX) of n -dodecane. Ti-doped MoO 2 nanoparticles were synthesized via solvothermal cracking of polycrystalline MoO 3 microparticles prepared by ultrasonic spray pyrolysis in the presence of a Ti precursor. Partial oxidation of n -dodecane was conducted at 850 °C with an O 2 /C ratio of 0.5. The 6 at% Ti-doped MoO 2 was fully converted into orthorhombic carbide phase (β-Mo 2 C) during the reaction. This carbide sample showed high catalytic activity and stability with conversion and H 2 yield of 94.4% and 86.3% after 24 h on stream, respectively. On the other hand, un-doped MoO 2 was partially converted into the carbide phase during the reaction, which led to mixed oxide and carbide phases. This mixed phase showed poor catalytic activity and rapid deactivation after only 6 h of operation. Our ammonia temperature programmed desorption (TPD) and pyridine diffuse reflectance infrared Fourier transform (DRIFT) tests suggest that the addition of Ti to MoO 2 improves both the density and strength of Lewis acid sites, and hence improves hydrocarbon activation. This increased surface carbon activation would enhance the carburization process of the Ti-doped MoO 2 catalyst and retain the carbide phase under the POX condition. [ABSTRACT FROM AUTHOR]