Preparation of novel catalyst-free Fe3C nanocrystals encapsulated NCNT structured catalyst for continuous catalytic wet peroxide oxidation of phenol

Novel nitrogen-doped carbon nanotubes encapsulating Fe3C nanocrystals coated paper-like sintered stainless steel fibers (PSSF) structured catalyst (Fe3C@NCNT/PSSF) was designed for continuous catalytic wet peroxide oxidation of phenol. Firstly, Fe3C@NCNT/PSSF was fabricated by directly growing the Fe3C encapsulated NCNTs onto the three-dimensional PSSF substrate through CVD method using melamine as precursor, the monolithic PSSF substrate served as a self-catalyzing agent for catalyst preparation. Secondly, the surface morphology and structure of Fe3C@NCNT/PSSF were investigated to optimize the synthesis condition. Then Fe3C@NCNT/PSSF was employed as a structured catalyst for continuous CWPO of phenol, effect of operating conditions was studied. Catalytic results showed that the encapsulated Fe3C nanoparticles significantly enhanced the degradation efficiency of phenol, and catalytic performance was improved with the increase of temperature. However, catalytic performance appeared unusual when residence time was considered, due to the effect of strongly polar surface of NCNTs on the contact efficiency between pollutants and hydroxyl radicals. Reusability experiments showed that catalytic performance of catalyst was improved with the increase of reusability cycles although the iron leaching concentration decreased, attributing to enhanced reaction within internal channel of Fe3C@NCNT. The fourth reaction run achieved a stable phenol conversion of 90%, TOC conversion around 41% under optimized conditions.