3.1.2.1. XRD analysis. The XRD patterns of calcined Ni-based samples
prepared by different impregnation sequences are displayed in
Fig. 3(a). All samples exhibited the characteristic peaks of NiO at
43.3, 62.9 and 76.3, and the characteristic peaks of g-Al2O3 at 2q
angle of 37.2, 45.8 and 66.9