title: Toluene removal by sequential adsorption-plasma catalytic process: Effects of Ag and Mn impregnation sequence on Ag-Mn/γ-Al2O3.
abstract: A series of Ag-Mn/γ-Al2O3 were prepared under different Ag/Mn impregnation sequence and tested in the sequential adsorption-plasma catalytic removal of toluene. When Mn was impregnated first, the resulting catalyst, Ag-Mn(F)/γ-Al2O3, had longer breakthrough time, gave less emission of toluene, had higher CO2 selectivity, and had better carbon balance and COx yield compared to catalysts prepared via other impregnation sequences. After 120 min of NTP treatment, the carbon balance of Ag-Mn(F)/γ-Al2O3 was 91%, with 87% as COx contributions. A Brunauer-Emmett-Teller (BET) analysis and X-ray photoelectron spectroscopy (XPS) results show that, the impregnation sequence impacts the BET surface area and the ratio and existing state of Ag on the surface of the catalysts. The longer breakthrough time when using Ag-Mn(F)/γ-Al2O3 as catalyst is attributed to the large amount of Ag(+) on the surface. Ag(+) is a new active site for toluene adsorption. When Ag was impregnated first (Ag(F)-Mn/γ-Al2O3) or Ag and Mn co-impregnated (Ag-Mn-C/γ-Al2O3), the predominant specie was Ag(+). Both Ag(0) and Ag(+) species were detected on Ag-Mn(F)/γ-Al2O3. Ag(0) cooperation with MnOx may promote the migration of surface active oxygen. This would facilitate the oxidation of adsorbed toluene with CC bond already weakened by Ag(+) and would result in higher CO2 selectivity and better carbon balance as seen in the Ag-Mn(F)/γ-Al2O3 system.
authors: School of Environmental and Municipal Engineering, Xi'an University of Architecture and Technology, No. 13 Yanta Road, Xi'an, Shaanxi 710055, PR China.
authors: Caihong
authors: C
authors: Qin
authors: School of Environmental and Municipal Engineering, Xi'an University of Architecture and Technology, No. 13 Yanta Road, Xi'an, Shaanxi 710055, PR China.
authors: Xuemin
authors: X
authors: Huang
authors: School of Environmental and Municipal Engineering, Xi'an University of Architecture and Technology, No. 13 Yanta Road, Xi'an, Shaanxi 710055, PR China. Electronic address: xiaoqingdang@hotmail.com.
authors: Xiaoqing
authors: X
authors: Dang
authors: Research Center of Air Pollution Control Technology, Chinese Research Academy of Environmental Science, Beijing, 100012, PR China.
authors: Jiayu
authors: J
authors: Huang
authors: School of Environmental and Municipal Engineering, Xi'an University of Architecture and Technology, No. 13 Yanta Road, Xi'an, Shaanxi 710055, PR China.
authors: Jingjing
authors: J
authors: Teng
authors: School of Environmental and Municipal Engineering, Xi'an University of Architecture and Technology, No. 13 Yanta Road, Xi'an, Shaanxi 710055, PR China.
authors: Zhongli
authors: Z
authors: Kang
mesh_terms: D000327:Adsorption; D000393:Air Pollutants / Q000032:analysis* / Q000737:chemistry; D000537:Aluminum Oxide / Q000737:chemistry*; D002384:Catalysis; D008345:Manganese / Q000737:chemistry*; D008962:Models, Theoretical; D010084:Oxidation-Reduction; D056951:Photoelectron Spectroscopy; D058626:Plasma Gases / Q000737:chemistry*; D012834:Silver / Q000737:chemistry*; D013499:Surface Properties; D014050:Toluene / Q000032:analysis* / Q000737:chemistry
chemical_list: D000393:Air Pollutants; D058626:Plasma Gases; D014050:Toluene; D012834:Silver; D008345:Manganese; D000537:Aluminum Oxide
keywords: Adsorption; Impregnation sequence; Plasma catalysis; Toluene