Valihura K. Effect of the composition of Mg(II), Al(III), Zr(IV) oxide systems on their catalytic properties in the processes of gas-phase conversion of ethanol and 1-butanol with doubling of the carbon chain

Scientific approaches to development of catalysts for multistage processes of gas-phase ethanol and 1-butanol conversion with doubling of a carbon chain are developed in the thesis. Based on elucidation of the influence of components of MgO-Al2O3(CeOx) and ZrO2-MxOy (M = Ce, Y) catalytic systems on their acid-base surface characteristics and determination of methods of their varying, the ways to achieve the high activity and selectivity of catalysts in gas-phase ethanol → 1-butanol and 1-butanol → 2-ethyl-1-hexanol conversion are proposed. The process of gas-phase condensation of 1-butanol to 2-ethyl-1-hexanol in the flow reactor over Mg-Al-oxide catalytic systems was realized for the first time. The possibility of sequential ethanol → 1-butanol → 2-ethyl-1-hexanol conversion at atmospheric pressure in the flow mode was confirmed. It will allow to obtain 2-ethyl-1-hexanol directly from ethanol. It is shown that for the efficient conversion of initial alcohols into target products (1-butanol and 2-ethyl-1-hexanol) the binary oxide catalyst MgO-Al2O3 should include Lewis acid-base pairs (Mg-O-Al) formed under the conditions of calcination of hydrotalcites. The highest yield of 1-butanol (18%) is achieved over the catalyst with a ratio of Mg/Al = 2, and the highest yield of 2-ethyl-1-hexanol (11%) is achieved over catalyst with a ratio of Mg/Al = 1. It is found that modification of Mg-Al oxide systems by Се3+ cations during the hydrotalcite synthesis leads to an increase in the concentration of acid and base sites on the catalyst surface, which provides an increase in the specific rate of 1-butanol formation comparing to unmodified catalyst. The highest yield of 1-butanol (14%) is achieved over the catalyst with a ratio of Mg/Al/Ce = 2:0.9:0.1. It is established that the CeO2, Y2O3 additives affect the phase composition of ZrO2, which determines the acid-base properties of its surface. As a result of stabilization of the tetragonal phase of ZrO2 by the addition of CeO2 and Y2O3 there is an increase in the basicity of the catalysts which leads to an increase in the selectivity of 1-butanol formation from ethanol in their presence. It is found that the sample with a 10 wt.% of CeO2 is characterized by the highest concentration of base sites on the surface among the studied ZrO2-CeO2 systems, which provides a twofold increase in the selectivity and productivity of the catalyst for 1-butanol formation comparing with unmodified ZrO2. It is shown that the introduction of a modifying additive Y2O3 and calcination of the Zr-Y-oxide system at 500 °C leads to an increase in the concentration of the base sites on the surface of the catalysts together with a decrease in the concentration of acid sites. Over the ZrO2-Y2O3 catalyst the high values of selectivity (up to 70%) and yield of 1-butanol (17%) are achieved. MgO-Al2O3 catalytic systems with the ratio of Mg/Al = 1 and 2 are suggested for ethanol → 1-butanol and 1-butanol → 2-ethyl-1-hexanol conversion processes, which provide productivity of 1-butanol formation 87 gBuOH/(kgcat·h) and 2-ethyl-1-hexanol 40 g2-EH/(kgcat·h). The priority of development is protected by the Patent of Ukraine for Utility Model. It is found that the usage of ZrO2-Y2O3 catalytic system (3.4 wt.% Y2O3, calcination temperature 500 °C) in the ethanol → 1-butanol conversion, provides selectivity for 1-butanol up to 70%, with the productivity of 27 gBuOH/(kgcat·h). The priority of development is protected by the Patent of Ukraine for Utility Model. These systems are promising for the creation of high-performance catalysts for the synthesis of 1-butanol and 2-ethyl-1-hexanol from ethanol.