Preparation of Nitrogen-Doped Carbon from Polyacrylonitrile and its Application as a Solid-Base Catalyst

N-doped carbon (N carbon) materials were prepared from a commercial polyacrylonitrile (PAN) by calcination and subsequent ammoxidation and these were used for a model reaction of Knoevenagel condensation of benzaldehyde and ethyl cyanoacetate. The catalytic activity of the calcined PAN for the reaction was very low, but it was greatly enhanced by the ammoxidation and the enhancement depended on both the calcination and ammoxidation temperatures. X-ray photoelectron spectra indicated the presence of pyridine-type and pyrrole-/pyridone-type N species and the amount of the former N species was well correlated with the catalytic activity. It was suggested that the presence of pyridine-type N in the graphene structure is significant for the emergence of the catalytic activity. The most active N-carbon catalyst prepared in the present study was much more active than solid-based catalysts reported so far including N carbon derived from activated carbon, N-doped carbon nanotubes, and a few metal oxide based catalysts.