Synthesis, characterization, and catalytic activity of nitridated magnesium silicate catalysts

Abstract

Amorphous and crystalline magnesium silicates (MgSils) were prepared by sol-gel and template-assisted hydrothermal synthesis methods, respectively. The obtained materials were nitridated with NH3 at 300, 500, and 800 C for 24 and 48 h generating nitridated MgSil catalysts. The catalysts were characterized by XRD, FTIR, TG-MS, N2-physisorption, Hammett indicators, and elemental analysis methods. MgSils nitridated at 300 C were found to be more active for the Knoevenagel condensation reaction, compared to those nitradated at 500 or 800 C. A larger amount of nitrogen was incorporated in the framework of amorphous MgSil compared to the crystalline MgSil. FTIR analysis indicated the presence of NH x species, which were known to form upon reaction between NH3 and M-OH groups. It was also found that the presence of Si-OH and Mg-OH groups along with the basic -NH2 functional groups is responsible for the enhanced catalytic activity of the low-temperature nitridated catalysts. © 2013 Springer Science+Business Media New York.