Impregnated active carbons to control atmospheric emissions I. Influence of the impregnated species on the porous structure

被引:16
作者
Alvim-Ferraz, MCM [1 ]
Gaspar, CMTB [1 ]
机构
[1] Univ Porto, Fac Engn, Dept Engn Quim, LEPAE, P-4100 Oporto, Portugal
关键词
olive stones; microporosity; mesoporosity; activation catalysis; CoO; Co3O4; CrO3;
D O I
10.1016/S0021-9797(02)00171-6
中图分类号
O64 [物理化学(理论化学)、化学物理学];
学科分类号
070304 ; 081704 ;
摘要
Impregnated active carbons were prepared to be used as catalysts for complete oxidation, aiming at the reduction of atmospheric emission of volatile organic compounds. Good dispersion of the catalyst is required, as it regulates the conversion efficiency in the pores where pollutants can access to be converted. When impregnation is performed on the raw material or after activation, the influence of impregnated species on the structure and on the catalyst dispersion is already well studied. This paper aims to analyze the influence of impregnated species on the structure and on the catalyst dispersion when the impregnation step is performed after carbonization, as this knowledge is yet very scarce. Olive stones were used as raw material. In order to evaluate the influence of the methodology of impregnation with CoO, Co3O4, and CrO3, the impregnation step was completed after activation and between carbonization and activation. In the first sequence, the impregnated oxides must be deposited on the internal surface, blocking part of the initial microporous structure. When impregnation is conducted after carbonization, metal species act as catalysts during the activation step. The structure developed strongly depends either on the chemical state of the catalyst or on its distribution in the carbonized material. A well-developed pore structure can appear just where metal species can access, remaining a micropore structure with pores of very small sizes. The better efficiency Of Co3O4 as a catalyst of the activation step is conditioned by a worse distribution of the carbonized material, related to the bigger size of its crystals. CrO3 is the least efficient catalyst for the activation step. (C) 2003 Elsevier Science (USA). All rights reserved.
引用
收藏
页码:133 / 138
页数:6
相关论文
共 18 条
[1]  
Alvim-Ferraz M. C. M., 1989, FUEL, V68, P635
[2]  
ALVIMFERRAZ MCM, 1988, FUEL, V67, P1237
[3]  
ALVIMFERRAZ MCM, 1999, FUEL, V78, P1567
[4]  
ALVIMFERRAZ MCM, 1983, THESIS FACULDADE ENG
[5]   Optimization of conditions for the preparation of activated carbons from olive-waste cakes [J].
Baçaoui, A ;
Yaacoubi, A ;
Dahbi, A ;
Bennouna, C ;
Luu, RPT ;
Maldonado-Hodar, FJ ;
Rivera-Utrilla, J ;
Moreno-Castilla, C .
CARBON, 2001, 39 (03) :425-432
[6]   Study on active carbon-supported two-component catalysts for NO conversion [J].
Bekyarova, E ;
Khristova, M ;
Mehandjiev, D .
JOURNAL OF COLLOID AND INTERFACE SCIENCE, 1999, 213 (02) :400-404
[7]  
BRADLEY RH, 1991, 20 BIENN C AM CARB S, P90
[8]   Low temperature complete combustion of methane over Ag-doped LaFeO3 and LaFe0.5Co0.5O3 perovskite oxide catalysts [J].
Choudhary, VR ;
Uphade, BS ;
Pataskar, SG .
FUEL, 1999, 78 (08) :919-921
[9]   The effects of carbonization temperature on pore development in palm-shell-based activated carbon [J].
Daud, WMAW ;
Ali, WSW ;
Sulaiman, MZ .
CARBON, 2000, 38 (14) :1925-1932
[10]   Interactions between molybdenum and activated carbons on the preparation of activated carbon-supported molybdenum catalysts [J].
de la Puente, G ;
Centeno, A ;
Gil, A ;
Grange, P .
JOURNAL OF COLLOID AND INTERFACE SCIENCE, 1998, 202 (01) :155-166