Nitrogen and phosphorous‐doped porous carbon xerogels as metal‐free catalysts for environmental catalytic peroxide oxidation of 4‐nitrophenol

Abstract

AbstractThis work reports an environmental benign porous carbon catalyst for the catalytic peroxide oxidation of 4‐nitrophenol (4‐NP) pollutant. Nitrogen and phosphorous‐doped carbon xerogels as metal‐free catalysts, which are namely as CX30, CX50 and CX75 with corresponding to initial concentrations of H3PO4 acid (30, 50 and 75 v/v %) were synthesized. Nitrogen gas adsorption measurements of the prepared carbon catalysts were performed at −196 °C, while Fourier transform infrared spectroscopy (FTIR) and high resolution scanning electron microscopy–energy dispersive X‐ray spectroscopy (SEM–EDS) analyses were examined for the sample of CX75 which appeared high catalytic performance. The effect of various factors such as temperature, catalyst loading, H2O2 dose and initial concentration of 4‐NP on the catalytic oxidation performance of the metal‐free catalysts was studied at pH = 4. Results revealed that the phosphoric acid activation of nitrogen‐doped resorcinol‐formaldehyde xerogel developed significant influence on the porosity and surface chemistry characteristics of the hereby catalysts. Increasing the concentration of H3PO4 enhances the microporosity at expense of mesoporosity yielding micro‐mesoporous carbons with surface area as high as 442 m2/g. EDS and FTIR analyses confirmed the presence of phosphorous‐ and nitrogen‐containing functional groups with high content of carbon and oxygen groups. During catalytic wet peroxide oxidation experiments, the CX75 catalyst exhibits complete decomposition 4‐NP (100%) within 60 min. Moreover, reusability experiments with this catalyst were run through three cycles and revealed high stability where up to 52.6% conversion of 4‐NP in the third recycle was occurred at 120 min. © 2016 Curtin University of Technology and John Wiley & Sons, Ltd.