Carbonization of Chitosan in Palladium-Chitosan/ Montmorillonite Composites to Prepare Novel Heterogeneous Catalysts for Heck Reactions

ABSTRACTPalladium-carbon/montmorillonite (Pd-C/MMT) heterogeneous catalysts were prepared by carbonization of chitosan in palladium-chitosan/montmorillonite (Pd-CS/MMT) composites under a N2 atmosphere. The main purpose of this study was to determine the effects of the carbonization temperature (250, 450, and 650°C) on the material microstructure and its catalytic performance. X-ray diffraction patterns revealed that the formation of an intercalation of the carbonaceous material between the clay mineral layers which was also confirmed by Fourier transform infrared spectra results. The N content of the Pd-C/MMT catalyst decreased as the carbonization temperature was increased. Thermogravimetry curves revealed that the thermal stability of the Pd-C/MMT catalyst increased obviously as the carbonization temperature was increased. Pd nanoparticles, sized at about 20 nm, were mainly dispersed on the surface of the MMT, as observed by high-resolution transmission electron microscopy (HR-TEM). The prepared Pd-C/M...