The studies of metal-oxide nanostructured systems (ZnO(Cu,Ag)/MgO-SiO₂, ZnO(Cu,Ag)/ZrO₂-(La₂O₃)-SiO₂, MgO-Al₂O₃-(CeO_x,La₂O₃)) in the hydrous ethanol condensation with the production of 1,3-butadiene and 1-butanol have been performed [2-10]. The procedure of catalyst preparation and the presence of dopants significantly affect its acid-base characteristics and dehydrogenation ability. It was shown that the ratio of MgO:SiO₂ and MgO:Al₂O₃ is a key parameter determining the acid-base characteristics and the catalytic properties of ZnO/MgO-SiO₂ and MgO-Al₂O₃-(CeO_x) in the processes of 1,3-butadiene and 1-butanol obtaining from ethanol. Based on the results of XRD, XPS, NMR, EPR and TPD-NH₃/CO₂, these effects are induced by the formation of active sites in the contact zone of nanoparticles of individual oxide phases. It was found that the preparation of ZnO/ZrO₂-SiO₂ catalyst by wet-kneading of ZnO nanoparticles with ZrO₂-SiO₂ system instead of the impregnation of ZrO₂-SiO₂ with a zinc salt solution makes it possible to obtain a more active catalyst [5]. The introduction of lanthanum into Zn(Zr)-Si-oxide systems noticeably enhances their activity in the ethanol to 1,3-butadiene conversion. This impact is attributed to the formation of additional basic sites on the catalyst surface [3, 4, 7]. The modification of MgO(ZrO₂,La₂O₃)-SiO₂ catalysts with Cu and Ag species allows to increase their activity and selectivity during the conversion of ethanol-water mixtures to 1,3-butadiene. It’s caused by the formation of active sites for ethanol dehydrogenation and new acid-base sites for the reactions of aldol and croton condensation of acetaldehyde with the formation of 1,3-butadiene. It was also shown that cerium modification of MgO-Al₂O₃ catalyst leads to an increase in 1-butanol selectivity. Such effect connected with the rising of specific rate of acetaldehyde formation due to an increase in the number of basic sites and their surface density. Wherein, the rate of ethanol dehydration with the formation of ethylene and diethyl ether is reduced, apparently, due to a decrease in a number of Lewis acidic sites formed by Al³⁺ cations octahedrally coordinated to oxygen [9, 10].

[1]      R. A. Dagle, A. D. Winkelman, K. Karthikeyan, V. L. Dagle, and R. S. Weber, “Ethanol as a renewable building block for fuels and chemicals,” Ind. Eng. Chem. Res., vol. 59, no. 11, pp. 4843–4853, 2020.

[2]      O. V. Larina, P. I. Kyriienko, and S. O. Soloviev, “Ethanol conversion to 1,3-butadiene on ZnO/MgO-SiO₂ catalysts: Effect of ZnO content and MgO:SiO₂ ratio,” Catal. Letters, vol. 145, no. 5, pp. 1162–1168, 2015.

[3]      O. V Larina, I. M. Remezovskyi, P. I. Kyriienko, S. O. Soloviev, and S. M. Orlyk, “1,3-Butadiene production from ethanol-water mixtures over Zn–La–Zr–Si oxide catalyst,” React. Kinet. Mech. Catal., vol. 127, no. 2, pp. 903–915, 2019.

[4]      O. V. Larina et al., “The effect of ZnO on acid-base properties and catalytic performance of ZnO/ZrO₂-SiO₂ catalysts in 1,3-butadiene production from ethanol-water mixture,” Catal. Sci. Technol., vol. 9, pp. 3964–3978, 2019.

[5]      O. V Larina et al., “Successive vapour phase Guerbet condensation of ethanol and 1-butanol over Mg-Al oxide catalysts in a flow reactor,” Appl. Catal. A Gen., vol. 588, no. September, p. 117265, 2019.

[6]      O. V. Larina et al., “Design of effective catalysts based on ZnLaZrSi oxide systems for obtaining 1,3-butadiene from aqueous ethanol,” ACS Sustain. Chem.Eng., vol. 8, no. 44, pp. 16600–16611, 2020.

[7]      P. I. Kyriienko et al., “1,3-Butadiene production from aqueous ethanol over ZnO/MgO-SiO₂ catalysts: Insight into H₂O effect on catalytic performance,” Appl. Catal. A Gen., vol. 616, p. 118081, 2021.

[8]      P. I. Kyriienko, O. V. Larina, S. O. Soloviev, and S. M. Orlyk, “Catalytic conversion of ethanol into 1,3-butadiene: Achievements and Prospects: A Review,” Theor. Exp. Chem., vol. 56, no. 4, pp. 213–242, 2020.

[9]      O. V. Larina et al., “Catalytic performance of ternary Mg-Al-Ce oxides for ethanol conversion into 1-butanol in a flow reactor,” J. Fuel Chem. Technol., vol. 49, no. 3, pp. 346–357, 2021.

[10]   O. V. Larina, K. V. Valihura, T. Čendak, “Effect of the cerium modification on acid–base properties of Mg–Al hydrotalcite‑derived oxide system and catalytic performance in ethanol conversion,” React. Kinet. Mech. Catal., vol. 132, pp. 359–378, 2021.