Characterization and quantification of the NH3 modification of a BCl3-treated silica gel surface

Abstract

The reaction of NH3 with a well characterized silica surface containing SiOBCl2 surface species has been studied using FTIR photoacoustic spectroscopy and quantitative boron, chloride and ammonia analysis. The influence of reaction time and temperature on the reaction was studied. Characterization of the reactions occurring and the surface species formed was carried out. Both surface siloxane groups and SiOBCl2 species interact with NH3, resulting in the formation of NH4Cl, chemisorbed amine groups and SiOH groups. Borazine-like surface species are formed at higher temperatures. A quantitative description of the grafted groups has been obtained as a function of reaction temperature.