Effect of nickel loading on the isothermal carburation of molybdenum trioxide catalyst

The carburization behaviour of nickel molybdenum trioxide (Ni-Mo03) catalyst with different loadings of Ni has been studied by using temperature programmed reduction (TPR) with exposure of 60 vol. % carbon monoxide (CO) in helium atmosphere as a reductant. The Ni-Mo03 catalysts were prepared by using the conservative wet impregnation method. The carburization characteristics of prepared catalysts were examined by isothermal carburization mode at 700°C for 90 minutes. The carburized phases were characterized by using X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) and field emission scanning electron microscopy (FE-SEM). XR D pattern of undoped M0O3 show the formation of molybdenum dioxide (M0O2) (20 = 37° and 74.10°) and M02C (20 = 33.63° and 62.50°). After addition of nickel at higher loading which is 3% (wt./wt.) of Ni-Mo03 show the XR D pattern obtained M02C at 20 = 61.47°, showing that the higher loading of nickel in M0O3 lead to higher reducibility compared to 1% (wt./wt.) of Ni-MoOs indicated by the broad and weak peak resulted from XRD pattern. By calculating the crystallites size 7.11 nm for 3% (wt./wt.) Ni-Mo03 catalyst give the higher crystallinity compared to 1% (wt./wt.) Ni-Mo03 catalyst which is 5.70 nm. Physical properties analysis by using BE T showed an increasing in surface area and pore size of M0O3 catalyst after addition of Ni metal loading. This proves that the higher loading of nickel might attribute to the increasing in active site for enhancing the carburization process which lead to the formation of M02C. The slightly phase covering the surface of the particles or seemed like an agglomerate is amorphous deposited carbon that formed between the platelet shape on Ni-Mo03 surfaces were observed through the FE-SEM images indicating some morphology modification occurred on M0O3. Based on these results, it is interesting to address that the addition of Ni metal to M0O3 has a remarkable influence on carburization process. The 3% (wt./wt.) of Ni on M0O3 catalyst was sufficient to promote the formation of M02C.