Vapor phase butanal self-condensation over unsupported and supported alkaline earth metal oxides

► Silica supported MgO, SrO and MgOSrO and MgO/HY had almost five times higher activity and higher stability compared to the unsupported MgO at 300 °C. ► Acid/base bifunctionality and week surface bonding of butanoic acid are required for the improved catalyst for butanal vapor phase condensation. ► Butanoic acid, a reaction intermediate, was the main cause of supported catalyst deactivation at the low reaction temperature. ► A reaction network for butanal vapor phase condensation has been proposed.