Field study on PCDD/F decomposition over VOx/TiO2 catalyst under low-temperature: Mechanism and kinetics analysis

One commercial granular catalyst was investigated, including catalysts characteristics, removal efficiencies (RE) and mechanism of polychlorinated-rho-dibenzodioxins and dibenzofurans (PCDD/F) and NOx, kinetics analysis of PCDD/F. The high surface area (96.77 m2/g), the dominative species of V5+ (74.79%), and good redox ability and anatase-TiO2 provided the advantages on catalysis of PCDD/F. The RE of PCDD/F were high and followed 94.59% for total PCDD/F (95.43% for toxic PCDD/F)>90.57% (91.74%)>87.48% (84.98%), with decreasing operating temperature of SCR (200 degrees C, 180 degrees C and 160 degrees C, respectively), which were closely associated with the decreasing catalytic reaction rate (k). While the RE of NOx was generally low and decreased from 67.51% to 45.03% and 42.74%, respectively. The catalyst better favors the PCDF removal in higher operating temperature (200 degrees C, 180 degrees C) but PCDD removal in lower temperature (160 degrees C). Kinetics analysis revealed the k of most PCDD/Fs generally decreased with the decreasing operating temperature, and the correlation coefficient (R2) with the k of PCDD, PCDF and PCDD/F were 0.91, 0.99 and 0.97, respectively. The apparent activation energy (Ea) of PCDD/F was 14.40 kJ/mol, and the Ea of PCDD (11.26 kJ/mol) was lower than that of PCDF (17.11 kJ/ mol).