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The scale-up procedure of the acetone-furfural aldol condensation was studied on Mg-Al mixed oxide (molar ratio of 3:1). The catalyst’s stability was evaluated in three consecutive condensation steps at 60–70 °C, WHSV = 1.6–2/h-1and the acetone-furfural molar ratio of 5:1 (mol:mol). After each condensation step, the catalyst’s reactivation was performed at 450 °C, ambient pressure under 50 NL/h nitrogen flow for 4 h. The experiments showed that catalyst deactivation was an effect related to the amount of treated feedstock. Moreover, our results showed the possibility of deactivation compensation by increasing reaction temperature or decreasing feeding rate. From a reaction mechanism point of view, furfural reacted first with acetone to FAc (4-(2-furyl)-3-buten-2-one), a crucial compound for heavier compounds formation.

In recent years, for deeper understanding of the behavior of various heterogeneous catalysts, aldol condensation of acetone and furfural has been researched in detail. In this article, the carbonyl reactants are represented by cyclohexanone and furfural as the platform chemicals for synthesis the fundamental building blocks for future biorefineries. Our main goal was to explore the structural and acid–base properties and to compare them with catalytic characteristics of Mg/Al mixed oxides in aldol condensation of cyclohexanone with furfural. The aforesaid basic heterogeneous catalysts were obtained by the calcination of commercially and laboratory prepared hydrotalcites with different molar ratios (1:1–5:1). Their physicochemical properties were determined based on several analytical methods: XRD, ICP-OES, SEM, N2physisorption, TGA, TGA-MS, DRIFT, TPD-CO2and TPD-NH3. Through XRD, it was found that as-synthesized laboratory hydrotalcites had the pure crystalline hydrotalcite structure while commercial ones contained also the brucite and MgO phases. By using TPD-CO2and TPD-NH3, the measured values, especially the total amount of basic sites, provided the best correlation with the catalytic activity of investigated catalysts. Comparable conversions of furfural (ca. 87%) were achieved on laboratory and commercial mixed oxides with the Mg/Al molar ratio 1:1 and 3:1, respectively. They had no obvious difference in selectivity to FCH (about 20%) whereas the commercial samples showed higher selectivity to F2CH (26% at max conversion) than the laboratory ones (17%).