Phosphorus-doped ordered mesoporous carbons embedded with Pd/Fe bimetal nanoparticles for the dechlorination of 2,4-dichlorophenol†
Palladium/iron (Pd/Fe) bimetallic nanoparticles were embedded within phosphorus-doped ordered mesoporous carbons (Pd/NZVI@P) with high dechlorination activity for 2,4-dichlorophenol (2,4-DCP). The Pd/Fe bimetal nanoparticles of about 15 nm diameter embedded in phosphorus-doped ordered mesoporous carbons (P-OMCs) were homogeneously distributed. The high dechlorination activity was mainly attributed to the homogeneous distribution of Pd/Fe bimetal nanoparticles, which were characterized by transmission electron microscopy (TEM) and scanning electron microscopy/energy dispersive X-ray spectrometry (SEM/EDS) with image mapping. Dechlorination kinetics indicated that the dechlorination rates of 2,4-DCP increased with the increasing of Pd content. The use of P-OMCs as supporting materials to embed enough Pd/Fe bimetal nanoparticles kept the nanoparticles highly active and stable. Besides, solution pH had a significant effect on the dechlorination of 2,4-DCP and the passivation of the Pd/NZVI@P samples. The effects of the number and position of chlorine atoms for different chlorophenols (CPs) on the dechlorination activity were also revealed; the result indicated that the dechlorination of CPs by catalytic reduction preferentially begins from the para-position of the ring, and more chlorine atoms of CPs are favorable for the occurrence of the dechlorination reaction. This study demonstrated that P-OMC is a promising supporting material for the preparation of some effective composite metals for the catalytic dechlorination of CPs.