The Guerbet reaction is a possible way for transformation of ethanol to 1-butanol (important for many kinds of industries), which consists of four steps: dehydrogenation, aldol condensation, dehydration, and hydrogenation. Due to the elimination of possible side-reactions, the selective catalysis is required to favour production of 1-butanol at temperature below 350 °C. The main aim of this work was the ethanol transformation via heterogeneous catalysis using active Mg–Al mixed oxides with copper or cobalt carried out in the microflow reactor in the reaction temperature interval 280–350 °C. The novelty lies in the statistical analysis of results from characterization of catalyst structure and surface with catalysis results providing more sophisticated perspective on the ethanol valorization. The series of Mg–Al catalysts containing copper showed an overall higher conversion of ethanol and selectivity to butanol compared to the series containing cobalt. Major difference of catalytic activity was at low reaction temperatures and at a lower copper content in the Mg–Al matrix, which is significant from the point of view of environmentally clean processes. A multi-step mechanism of the Guerbet reaction involving an aldol condensation was verified for both tested catalysts series and reaction conditions. Graphic abstract

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Ethanol, as a renewable raw material, is important source for preparation of higher alcohol and other add-value chemicals, which are currently produced from raw fossil materials. The Guerbet reaction is possible way to transformation of ethanol to 1-butanol (important for many kinds of industries), which consists of four steps: dehydrogenation, aldol condensation, dehydration, and hydrogenation. The reaction requires catalysis to favour 1-butanol, because of elimination of side reactions. The transformation was caried out via heterogeneous catalysis (Mg-Al mixed oxides with copper or cobalt) in the microflow reactor at three reaction temperatures (280, 300 and 350°C), which was the main aim of this work. The novelty especially lay in the statistically analysis of results from characterisations and catalysis (almost always omitted), which provided new perspective on the catalysis of the Guerbet reaction. The catalyst stability was proved by long term catalytic tests. The higher ethanol conversion, clear correlations of catalytic and characteristic data were achieved by copper dopped catalysts, compared to dopped by cobalt. Moreover, copper is more environmentally friendly, cheaper, and more used metal than cobalt.