3.1.1 Characterization of catalysts prepared by different
impregnation sequences
Table 1 The results show that g-Al2O3
support has a specific surface area of 191 m2/g, which was
decreased to 148 m2/g (16Ni/Al2O3) after loaded with 16wt% Ni,
probably because the pores were blocked by part of NiO nanoparticles
Al2O3 exhibited
higher specific surface area of 169 m2/g than other two catalysts of
Ni/Ce/Al2O3 and Ce/Ni/Al2O3.
The N2 adsorptionedesorption isotherms of the g-Al2O3 support
and the calcined catalysts prepared by different impregnation sequences
are shown in Fig. 2(a) and (b), respectively. As shown in
Fig. 2(a), all samples exhibited type IV isotherms and similar hysteresis
loops to the H4 type, characteristic of mesopores typical for
layered structures according to IUPAC
The pore size distribution of the catalysts shown in
Fig. 2(b) were narrow at ~5.5 nm, indicating the presence of mesoporous
structures in all catalysts.