Fine Copper Nanoparticles on Amine Functionalized SBA-15 as an Effective Catalyst for Mannich Reaction and Dye Reduction

Abstract

Copper nanoparticles dispersed on amine functionalised mesoporous silica SBA-15 (Cu/NH2-SBA-15) were synthesised by a simple sol–gel and impregnation method using sodium borohydride (NaBH4) as a reducing agent. The morphology, mesostructure and functionality of the ordered mesoporous Cu/NH2-SBA-15 were evaluated by powder X-ray diffraction (PXRD), Scanning electron microscopy (SEM), Transmission electron microscopy (TEM), Nitrogen adsorption–desorption isotherms (BET) and Fourier transform infrared spectroscopy (FTIR). The results obtained revealed, that the amine functionalised SBA-15 holds hexagonal lamelliform with surface area and pore size of 250 m2/g, 2.2 nm respectively. Moreover, these short vertical channels have a substantial role in the uniform dispersion of copper nanoparticles within the meso-channels of amine functionalised SBA-15. Cu nanoparticles in the size range of 4–7 nm were dispersed on the NH2-SBA-15 support. To confirm the potential catalytic activity, Cu/NH2-SBA-15 was tested in Mannich reaction. The catalyst showed an excellent catalytic activity for the yield (90%) of β-amino carbonyl compounds that serve as a building block for the synthesis of lactams, peptides, amino alcohols and precursor for various amino acids. Further, the activity of the catalyst was also tested for the reduction of dyes. The structural influence over the reduction pathways was studied on triphenyl methane dyes.