Knoevenagel condensation reaction on a new highly-efficient La2O2CO3-TiO2 mixed oxide catalyst: Composition-effects on C=C bond formation

The highly efficient catalytic abilities of some mixed oxides are due to cooperative interactions between acid and base functional groups present in their active sites. New La2O2CO3-TiO2 mixed oxide catalysts with different La/Ti molar ratios successfully synthesized through a facile solvothermal method were investigated for the Knoevenagel condensation reaction of various carbonyl compounds derivatives with malononitrile. The analytical determinations, including XRD, Raman, HRTEM, N-2 adsorption/desorption and TPD of CO2 and NH3, witnessed the structural characteristics of the as-prepared La2O2CO3-TiO2 mixed oxide catalysts. La2O2CO3-TiO2 mixed oxide catalyst having molar ratio La/La + Ti = 0.09 composition (La2O2CO3(0.09)-TiO2) exhibited highest conversion of benzaldehyde for Knoevenagel reaction of benzaldehyde with malononitrile. More importantly, this catalyst could be successfully applicable to the Knoevenagel condensation of various carbonyl compounds derivatives with high yields above 85%. This acid-base bifunctional synergetic effect between La2O2CO3 and TiO2 contributes to improve the catalytic property of the catalyst.