Effect of delamination on active base site formation over nitrided MWW-type zeolite for Knoevenagel condensation

High surface area zeolite is advantageous in base catalysis for large molecule synthesis via C-C bond formation. Delamination of layered zeolite precursors is one of the effective approaches to modify the microporous zeolite nature. In this study, a MWW-type zeolite precursor was delaminated under controlled treatment temperature and time and subsequently nitrided by ammonia. All nitrided products were employed to catalyze a model reaction, Knoevenagel condensation of benzaldehyde with ethyl cyanoacetate. Among several catalytic properties, the initial reaction rate was proportional to the external surface area. This indicates that there is no relation between the number of active sites and the amount of nitrogen on the entire surface. Together with the experimental results and the structural aspect of the MWW framework, it is proposed that delamination increases the external surface and eventually increases the unique Si-OH groups, which might be a precursor to the active Si-NH2 sites for the base-catalytic reaction.