кремнезем

The adsorption of glycine on amorphous silica surface has been studied to demonstrate the catalytic activity of silica surfaces towards the formation of peptide bonds on prebiotic earth. Silica nanoparticles were synthesized using a microwave assisted method and the nanoparticles were characterized using SEM. Glycine was adsorbed from aqueous solution on the nanoparticles and the adsorption behavior was characterized using FTIR and TGA analyses. At a glycine concentration of 0.5M and at pH=7, favorable adsorption was observed which obeyed the Langmuir isotherm model.

This work deals with synthesis, characterization and evaluation of post-metallocene complexes based on silica-supported bis(imino)pyridine iron, containing amino groups in ethylene polymerizations. The reaction of these complexes and methylaluminoxane generated active species in heterogeneous ethylene polymerization. The absence of substituents at the ortho-position of the phenyl rings near the metal site was not compensated by the steric hindrance of the silica surface, negatively affecting the catalytic activity and the molar mass of the produced polymer.

Melamine sulfate (Si-MelaSO4H) was prepared by treated melamine, which was immobilized onto silica (Si-Mela) with 0.05 M sulfuric acid at room temperature. The TGA confirmed that the thermal stability could reach 473 K. The XRD pattern showed that in some patterns there were sharp peaks and in other pattern a broad band was shown, which indicated that the surface is a mix of crystalline and non-crystalline nature. The Si-MelaSO4H was used successfully in the preparation of Schiff bases and its derivatives.