*2.2. The Textural Properties of Ni-xSi/ZrO2 Catalysts*

The physical properties of Ni-xSi/ZrO2 catalysts were characterized by N2 adsorptiondesorption experiments. Figure 3 showed the N2 adsorption-desorption isotherms, pore volume, and size distribution of the catalysts. All isotherms of the catalysts were assigned to the type IV isotherm and the P/P0 for the hysteresis loop was 0.7~0.9, which indicated that all the catalysts were with the mesoporous structure, and that also could be proved by the pore size distribution in Figure 2B [48–50]. The textural properties of catalysts were summarized in Table 1. The specific surface area was calculated by the Brunauer-Emmett-Teller (BET) method and the pore size and volume were calculated by the Barrett-Joyner-Halenda (BJH) method. Obviously, it could be seen that the BET results of catalysts with a different Si content had no significant differences, which suggested that the different loading of Si did not damage the pore structure of the Ni/ZrO2 catalyst.

**Figure 3.** N2 adsorption-desorption isotherms (**A**) and pore volume and size distribution (**B**) of Ni-xSi/ZrO2 catalysts.


**Table 1.** Textural properties and element contents of Ni-xSi/ZrO2 catalysts.

a: Surface area (SBET) determined by the BET method; b: BJH adsorption cumulative volume of pores; c: BJH adsorption average pore diameter; d: Obtained by XRF.

The actual loadings of Ni and Si were determined by the X-ray fluorescence (XRF) test. The content of Ni on Ni/ZrO2, Ni-0.1Si/ZrO2, Ni-0.5Si/ZrO2, and Ni-1Si/ZrO2 were 6.74%, 6.66%, 6.51%, and 5.79%, respectively. The actual contents of Ni on these catalysts were very close, indicating the successful loading of Ni onto ZrO2. The content of Si on Ni-0.1Si/ZrO2, Ni-0.5Si/ZrO2, and Ni-1Si/ZrO2 were 0.11%, 0.34%, and 0.58%.
