Reductive degradation of 2,4-dichlorophenoxyacetic acid using Pd/carbon with bifunctional mechanism

Abstract

In this study, commercial carbon nanofibers with different graphitic structure and commercial multiwall carbon nanotubes (CNT) were used. Palladium catalysts were prepared using these supports. Subsequently, they were tested in the hydrodechloration reaction of 2,4-dichlorophenoxyacetic acid under ambient-like conditions. Thermogravimetric analyses (TGA), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM) and nitrogen adsorption at 77 K techniques were applied to characterize the different materials. The results have demonstrated the efficiency of a bifunctional material in an integrated process that synergically combines physical adsorption and catalytic degradation. During the process, the carbon surface provides active sites to get chlorophenoxyacetic adsorbed. After saturation of the nanocarbon, the compound was decomposed by the catalytic function of supported Palladium catalysts. The study is focused on analyzing the effects of the support surfaces and electronic state of supported palladium nanoparticles on the catalytic performances. High selectivity to dechlorinated product was obtained with the catalysts prepared over more graphitic supports, whereas no-selectivity to dechlorinated products took place over oxygen-containing support. The mechanistic aspects of this bifunctional process were postulated based on the characterisation of these catalytic materials.