## 4 Conclusions  
In this study, a series of new, efficient catalytic systems of the general form, PS-NHPI@CoCl\({}_{2}\) @[emim][OcOSO\({}_{3}\)], which embody a combination of SCILL and SILP techniques, were used for ethylbenzene oxidation reactions. In order to prepare these systems, five heterogeneous chloromethyl polystyrene-NHPI (PS-NHPI) catalysts, differing in particle size distribution and content of the cross-linking agent, were synthesized by immobilizing the NHPI on the polymer supports. The obtained heterogeneous catalysts were characterized by SEM, FT-IR, and elemental analysis, and then were covered with the ionic liquid, [emim][OcOSO\({}_{3}\)], which contained dissolved CoCl\({}_{2}\). The ethylbenzene oxidation capabilities and outcomes obtained by the prepared PS-NHPI@CoCl\({}_{2}\)@[emim][OcOSO\({}_{3}\)] systems were compared with the systems composed of heterogeneous PS-NHPI and CoCl\({}_{2}\) (PS-NHPI/CoCl\({}_{2}\)) or IL (PS-NHPI/IL) added separately to the reaction mixture. Ethylbenzene was selected as a model hydrocarbon, and the reactions were carried out using dioxygen under atmospheric pressure. We showed that PS-NHPI catalysts exhibit catalytic activity for ethylbenzene oxidation using dioxygen in the presence of CoCl\({}_{2}\). Compared to the CoCl\({}_{2}\) reference reaction, they performed with a twofold increase in conversion, from about 4% to about 7-11%. Attempts to recycle PS-NHPI/CoCl\({}_{2}\) catalysts revealed that the systems' catalytic activities gradually decrease in each successive cycle, due to the removal of CoCl\({}_{2}\) with the reaction products. Covering the PS-NHPI-4 catalyst with the [emim][OcOSO\({}_{3}\)] ionic liquid layer did not affect the catalytic activity of immobilized NHPI. For example, both the PS-NHPI-4 and PS-NHPI-4@[emim] [OcOSO\({}_{3}\)] achieved conversions around 5%. This indicates that the ionic liquid covering PS-NHPI does not limit the contact between the reactants and the active centers of the catalyst, as is often observed in SCILL systems [38; 39; 41]. The integrated PS-NHPI@CoCl\({}_{2}\)@[emim][CoCOSO\({}_{3}\)] systems constructed using a combination of SCILL and SILP techniques showed increased acetophenone selectivity, but decreased ethylbenzene conversion, compared with the systems where PS-NHPI and CoCl\({}_{2}\) were added separately. The higher selectivities toward ketone production and lower selectivities toward ethylbenzene hydroperoxide observed for the SCILL/SILP systems may result from the higher CoCl\({}_{2}\) concentration in the IL layer, which promotes better contact between the co-catalyst and the products, including ethylbenzene hydroperoxide. The relatively high viscosity of the ionic liquid [44] also likely influences the course of the reaction due to the solvent \"cage\" effect [43]. Based on the results presented herein, it is possible to recycle the PS-NHPI@CoCl\({}_{2}\)@[emim][CoCOSO\({}_{3}\)] systems with only a slight decrease in the activity and selectivity to acetophenone observed in successive reaction cycles. The ionic liquid layer significantly reduces the leaching of CoCl\({}_{2}\), which leads to better recyclability and reuse options than for the PS-NHPI/CoCl\({}_{2}\) systems. The following are available online at [[http://www.mdpi.com/2073-4344/10/12/1367/s1](http://www.mdpi.com/2073-4344/10/12/1367/s1)]([http://www.mdpi.com/2073-4344/10/12/1367/s1](http://www.mdpi.com/2073-4344/10/12/1367/s1)), Figures S1-S5: SEM images of the PS-C1 resins; Figures S6-S10: SEM images of the PS-NHPI catalysts; Figure S11: FT-IR spectra of PS-C1-1 and PS-NHPI-1; Figure S12: FT-IR spectra of PS-C1-3 and PS-NHPI-3; Figure S13: FT-IR spectra of PS-C1-4 and PS-NHPI-4; Figure S14: FT-IR spectra of PS-C1-5 and PS-NHPI-5; Figure S15: FT-IR spectra of [emim][CoCOSO\({}_{3}\)]; Figure S16: FT-IR spectra of 1-phenylethanol; Figure S17: gasometric apparatus. Conceptualization, G.T. and B.O. ; methodology, G.T. and B.O. ; FT IR analysis, M.G. ; investigation, G.T. and A.O. ; writing--original draft preparation, G.T. and B.O.