Using Mn(II)−MCM41 as an Environment-Friendly Catalyst to Oxidize Phenol, 2-Chlorophenol, and 2-Nitrophenol in Aqueous Solution

Abstract

Mesoporous MCM41 modified by incorporation of Mn(II) was used as a catalyst for oxidation of phenol, 2-chlorophenol, and 2-nitrophenol in water with H2O2. Mn(II)−MCM41, obtained by both direct synthesis and impregnation, was characterized by XRD, SEM, and FTIR measurements. The cation exchange capacities of calcined MCM41 and synthesized and impregnated Mn(II)−MCM41 were 0.20, 0.21, and 0.26 mequiv g-1. The materials were calcined at 773−823 K for 6−24 h before using as catalysts in a high pressure stirred reactor at 0.2 MPa and 353 K under various reaction conditions. Oxidation of phenol, 2-chlorophenol, and 2-nitrophenol in 5 h was 86.5, 90.3, and 74.3% with the synthesized Mn(II)−MCM41 and 88.9, 90.3, and 87.6% with the impregnated Mn(II)−MCM41, respectively. The reaction followed pseudo-first-order kinetics with respect to phenol, 2-chlorophenol, or 2-nitrophenol, and the apparent kinetic constant was from 4.1 × 10-3 to 7.6 × 10-3 L (g of catal)-1 min-1. The results have been discussed with respect to the effects of various reaction conditions.