## 3 Results and Discussion
### Materials Characterization  
In the infrared spectra of the supported complexes (Figure 2), there are specific bands at approximately 1098, 794 and 448 cm\({}^{-1}\) that can be attributed to the vibrations of the mesoporous structure (Si-O), a band at 547 cm\({}^{-1}\) that can be assigned to the characteristic absorption of \(\beta\)-zeolite and mesoporous materials, and a broad band at approximately 3409 cm\({}^{-1}\) that can be assigned to silanol groups (SiO-H). The bands at 3154 and 3098 cm\({}^{-1}\) are assigned to the CH vibrations of the imidazole aromatic ring and the CH stretching of the alkyl groups belonging to the silylating agent. The bands at 2960 and 2870 cm\({}^{-1}\) in the spectra of the supported complexes are assigned to symmetric and asymmetric stretches of the CH bonds present in the complexes, suggesting that the complexes were immobilized on the support. \begin{table}
\begin{tabular}{c} Internal butenes mass \\ \(\Sigma\) butenes mass \\ \end{tabular} \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Expressions used for calculations of activity and selectivity of the oligomers. Figure 2: Infrared spectra of NiIL-Zeo\(\beta\), NiIL-MCM-41 and NiIL-Al-MCM-41. Figure 3 shows the diffractograms that contain peaks characteristic of supports modified with an ionic liquid (IL-Zeo\(\beta\), IL-MCMC-41 and IL-Al-MCM-41) as well as \(\beta\)-zeolite, MCM-41 and Al-MCMC-41 (upper right insets). Based on a comparison of the sets of spectra, we conclude that the network organization did not change, which confirms that the structure of these supports did not changed even after the immobilization of the silylated ionic liquid in their cavities. The spectra in Figure 3 are consistent with the XRD patterns reported in the literature [19]. Evaluation of specific regions of the spectra can be used to confirm the results obtained by XRD wherein the characteristics of the materials were maintained, even after incorporation of the ionic liquid. Analysis of these data showed significant reductions in the specific surface areas of the IL-Zeo\(\beta\) from 418 to 32 m\({}^{2}\) g\({}^{-1}\), the IL-MCM-41 from 1038 to 403 m\({}^{2}\) g\({}^{-1}\) and the IL-Al-MCM-41 from 860 to 465 m\({}^{2}\) g\({}^{-1}\) due to the incorporation of a substantial number of organic groups. These results suggest that the ionic liquid can be immobilized in the pores of the materials. Based on the elemental analysis, one can estimate the amount of ionic liquid that was anchored to each support. We obtained 8.92% C, 1.39% H and 2.29% N on the IL-Zeo\(\beta\) support; 7.28% C, 2.14% H and 2.31% N on the IL-MCM-41 support; and 10.57% C, 2.23% H and 2.76% N on the IL-Al-MCM-41 support. From these results, one can calculate the amount of ionic liquid incorporated into each medium; the relevant results were 22.0% (indicating that 41% of ionic liquid added was immobilized on the Zeo\(\beta\) support), 22.2% (indicating that 47% of ionic liquid added was immobilized on IL-MCM-41) and 27.5% (indicating that 61% of ionic liquid added was immobilized on IL-Al-MCM-41). The results of texture analysis from N\({}_{2}\) adsorption-desorption isotherms are shown in Table 2.  
Figure 3: X-ray diffractograms of the (**a**) \(\beta\)-zeolite and IL-Zeo\(\beta\); (**b**) MCM-41 (Mobil Composition of Matter 41) and IL-MCM-41; and (**c**) Al-MCM-41 and IL-Al-MCM-41. The specific areas were calculated by the BET method, resulting in 1038 m\({}^{2}\) g\({}^{-1}\) for the MCM-41, 860 m\({}^{2}\) g\({}^{-1}\) for the Al-MCM-41 and 418 m\({}^{2}\) g\({}^{-1}\) for the \(\beta\)-zeolite, and 403, 465 and 32 m\({}^{2}\) g\({}^{-1}\) for IL-MCM-41, IL-Al-MCM-41 and IL-\(\beta\)-zeolite, respectively. As expected, a decrease in BET surface area is observed in the ionic liquid-modified materials. To confirm the binding of the nickel complex to the \(\beta\)-zeolite, MCM-41 and Al-MCM-41, the heterogenized complexes were analyzed by flame atomic absorption.