Preparation of molybdenum-doped akaganeite nano-rods and their catalytic effect on the viscosity reduction of extra heavy crude oil

Highlights: • Mo-doped akaganeite nano-rods has been prepared by a facile hydrolysis method. • The nano-rods have been definitely characterized by XRD, FTIR, TEM, XPS, etc. • The formation of the nano-rods depend on the molar ratio of Mo to Fe. • The nano-rods are effective catalyst for the viscosity reduction of extra heavy oil. • The viscosity reduction mechanism of the extra heavy oil has been discussed. Molybdenum-doped akaganeite nano-rods were prepared by one step facile synthesis. The formation of akaganeite depends on the molar ratio of hexaammonium molybdate to ferric chloride hexahydrate. The nano-rods have an average particle size of ca. 30 nm and disperse uniformly. As a catalyst, the nano-rods can effectively increase the viscosity reduction rate of Shengli Oilfield extra heavy crude oil (175000 mPa s at 50 °C), especially combined with tetralin (a hydrogen donor). The results of SARA analysis, elemental analysis, and ¹H NMR spectra indicate that the increase of light component caused by the denitrification and desulfuration of the catalyst plus tetralin as well as the loosening of heavy component molecules can be responsible for the viscosity reduction of the heavy oil.