Heterogeneous Reaction of NH3 and Cl2 on the Surface of γ-Al2O3 Particles

The effect of NH3 concentration, reaction time and other conditions on the heterogeneous reaction of NH3 and Cl-2 on the surface of gamma-Al2O3 particles was investigated at the room temperature, pressure and in the presence of oxygen by ion chromatography (IC). The formation of the surface species (Cl-, NO3-, and SO42-) via both individual reaction and co-existing reaction of NH3, Cl-2, SO2 and NO2 on the surface of gamma-Al2O3 was investigated as well. The results revealed that NH3 (400 ppm) and Cl-2 (400 ppm) had synergistic effect on the surface gamma-Al2O3, and the total yield of Cl- was 589.65 mu g after reaction of 2 h. The formation of the surface chlorides increased firstly and then decreased with the increase of ammonia concentration, and the maximum yield of Cl- was reached at 400 ppm of NH3. In the presence of active chlorine, NH3 significantly promoted the generation of the adsorptive species on the surface, such as Cl-, NO3- and SO42-, and the most obvious synergistic effect was induced to form on the conditions of four gases co-existence. The heterogeneous reaction mechanism of NH3 with Cl-2 and the influence on the atmospheric environment were also discussed as well. Additionally, the mixing ratios used in the study are extremely high compared with ambient levels, which could be as a simulation to explore whether the synergistic effect obtained in this paper are also present in the real ambient conditions. We have studied a relatively low mixing ratios for heterogeneous reaction experiments, but the content of nitrate and chloride on the surface of gamma-Al2O3 were lower than the limit of detection of ion chromatography. Therefore, other researches such as Knudsen cell and smog chamber study, field monitoring, and mode study are also worth for exploring in future study. The results of this study could provide reference data for the study of the contribution of active chlorine and ammonia to the formation of secondary inorganic particles.