Potassium-doped carbon nitride supported on SBA-15 for enhanced catalytic Knoevenagel condensation under mild conditions

Knoevenagel condensation reaction is an important reaction for the manufacture of alpha,13-unsaturated carbonyl compounds. Traditional base catalysts suffer from the disadvantage in catalyst-product separation. Herein, potassium-doped carbon nitride materials supported on SBA-15 (CN/SBA15-KCl) have been prepared through a one-pot calcination method. The characterization results of N2 adsorption-desorption, small-angle XRD, TEM, and SEM revealed that the ordered mesostructures of SBA-15 had been preserved after the loading of carbon nitride and KCl, and nitrogen and potassium species were dispersed on the surface of SBA-15 support. As solid bases, the CN/SBA15-KCl materials demonstrated high and steady catalytic performances in Knoevenagel condensation. Under 50 degrees C of reaction temperature, the optimized conversion of benzaldehyde was up to 74% at 4 h of reaction time, much higher than other carbon-nitride-based materials. The incorporation of potassium has been proved to enhance the basic strength of CN/SBA15, and therefore improved the catalytic activity.