Preparation of amine-immobilized solid base catalysts by plasma polymerization of 1,2-diaminocyclohexane

Thin films were deposited onto silica–alumina powders by plasma polymerization of 1,2-diaminocyclohexane to prepare amine-immobilized solid base catalysts. The existence of amine moieties in the films was confirmed by solid-state 13C NMR, FT/IR, and XPS analyses. The silica–alumina powders deposited with the films showed strong base catalytic activity when evaluated based on the adsorption/desorption pattern of acidic gases (NO2 and CO2) and the conversion of benzaldehyde in Knoevenagel condensation reaction between benzaldehyde and ethylcynoacetate. Adsorbed acidic gases still remained even at 400 °C due to strong chemisorptions. When the plasma polymerization was carried out by a two-step process, the conversion was as high as 91.2% and adhesion of the films could be improved. The conversion was 82.0% even after the repeated use for 3 times when the films were deposited by the two-step process.

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► A novel approach for the preparation of solid base catalyst was investigated.
► Amine incorporated solid base catalyst was prepared by plasma deposition of DACH.
► Amine incorporated solid base catalyst showed good base catalytic activity.
► They can be repeated use for 3 times without loss of activity.