Boron-Carbon-Nitrogen-Containing Heterogeneous Catalysts for Base-Catalyzed Reaction

Abstract To advance green chemistry, further development of heterogeneous base catalysts rather than homogeneous catalysts is essential. In this study, boron-carbon-nitrogen (BCN)-containing materials were prepared and used as heterogeneous catalysts for a base-catalyzed reaction. The BCN materials were prepared by heat treatment of polyacrylonitrile at various temperatures (600, 800, and 1000 °C) and BCl3 concentrations (0.1, 0.5, and 1.0%) to control the composition of the BCN materials. The prepared samples were characterized by X-ray diffractometry, Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy, and N2 adsorption–desorption isotherms. We evaluated the catalytic activity of the samples using the Knoevenagel reaction of benzaldehyde with ethyl cyanoacetate to produce ethyl cyanocinnamate (ECC). Higher surface compositions of boron and nitrogen were obtained by introducing higher concentrations of BCl3 in the preparation process, which increased the ECC yield. Furthermore, the surface ratio of B-N-C-type nitrogen correlated with the ECC yield. The recycling test of the Knoevenagel reaction indicated that the BCN material gradually deactivated with increasing the number of runs, which is attributed to hydrolysis of the B–N site.