3.1.3. Textural Properties

Table 1 shows the BET surface areas and pore parameters for CeNiO3 and SrNiO3 perovskites. The observed values of 20.7 m2/g (CeNiO3) and 12.2 m2/g (SrNiO3) are rather low and similar to those previously reported for perovskite-type oxides calcined at 800 ◦C, which is higher than is generally reported in the literature (below 10 m2/g) for this type of material [37]. It is observed that the surface area of CeNiO3 catalyst is higher (20.7 m2/g) than SrNiO3 catalyst (12.2 m2/g). A similar trend is also observed for pore volume. Hence, CeNiO3 is expected to show higher activity than SrNiO3.

**Figure 2.** XRD patterns of SrNiO3 and CeNiO3 perovskites.

**Table 1.** DTG decomposition temperatures of SrNiO3 and CeNiO3 perovskites.


#### 3.1.4. Morphological Study (TEM) of Fresh Perovskites

The morphology of as-synthesized SrNiO3 and CeNiO3 perovskites was analyzed by using Transmission Electron Microscopy (TEM), and microscopic images of all the fresh, reduced, and used catalysts are shown in Figure 3. The analysis of TEM images was performed using ImageJ® software (version 1.5, National Institutes of Health, Bethesda, MD, USA). The spherical particles were found to have average sizes varying from 5 to 34 nm, and 13 to 24 nm for fresh CeNiO3, and SrNiO3 perovskites (Figure 3a,d), respectively, which increased slightly to 8–45 nm and 16–39 nm for CeNiO3, and SrNiO3 perovskites (Figure 3b,e), respectively, after reduction, indicating negligible sintering after activation.
