LAUSR

Abstract Solid Lewis-base catalysis is important in the production of fine chemicals. A Lewis-base Ga4B2O9 was synthesized by high temperature solid state reactions. It exhibited a high yield (90 %) and a high stability in Knoevenagel condensation reactions, where several aldehydes were combined with malononitrile to form α, β-unsaturated compounds through nucleophilic addition reactions. Reaction kinetics analyses indicated Knoevenagel condensation reactions over Ga4B2O9 catalyst obeyed a second-order characteristics and the calculated activation energy was ∼61.6 kJ/mol, suggesting that Langmuir-Hinshelwood absorption pathway was probably employed. The structural evolution from Ga4B2O9→GaBO3→β-Ga2O3 evidenced that the structure-induced basicity of Ga4B2O9 attributed to the special μ3-O atoms linked exclusively to 3 five-coordinated Ga3+. This investigation proves a convincible structure-property correlation in Ga-based solid base materials and helps developing an alternative avenue towards the design of new intrinsic solid base catalysts.