The activity of Rh/Al_2O_3 and Rh-Na/Al_2O_3 catalysts for PAHs removal in the waste incineration processes: Effects of particulates, heavy metals, and acid gases

摘要

This study investigated the activity of Rh/Al_2O_3 and Rh-Na/Al_2O_3 catalysts for polycyclic aromatic hydrocarbons (PAHs) removal and the influence of particulates, heavy metals, and acid gases (SO_2 and HCl) on the performance of catalysts. The experiments were carried out in a laboratory-scale waste incineration system. Experimental results show that the destruction removal efficiency (DRE) of PAHs by Rh/Al_2O_3 and Rh-Na/Al_2O_3 catalysts were 80% and 59%, respectively when the flue gas did not contain any pollutants. The concentrations of PAHs increased by using a Rh/Al_2O_3 catalyst when the flue gas contained Cd, Pb, and SO_2 and also increased by using a Rh-Na/Al_2O_3 catalyst when the flue gas contained particulates, Cd, and HCl. Adding Na to the Rh/A_l2O_3 catalyst can inhibit the increases of 3-4 ring PAHs when the flue gas contained Pb. The influence of acid gases on the performance of the Rh/Al_2O_3 and Rh-Na/Al_2O_3 catalysts followed the sequence SO_2 > HC1 > SO_2 + HC1. The activity of the catalysts for PAHs removal was significantly suppressed by increased concentrations in particulates and Cd, yet promoted by a high Pb concentration. The results of ESCA analysis indicated that the presence of Cd and Pb did not change the chemical states of Rh and Na, but the presence of SO_2 and HC1 did.