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Preparation of activated carbons from Spanish anthracite. I. Activation by KOH
04 By-products
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In India fly ash management is nearly 73% of the total installed power generation capacity, of which most is coal-based generation. Topics discussed include fly ash utilization trends in India, and issues on ash handling, ash pond management, ash utilization and facilitation for the 21st century. 02/00900 Grain size distribution of lsalnita power plant lignite ash and elemental composition of size classes Niac, G. e! cl/. F~,cJ/,2001, 80, (5). 731-737. Grain size analysis of 48 samples of Isalni(a power plant lignite ash revealed a mixture of three populations, each of them showing best fit to Weibull distribution with smallest size (.x~) 40, 350 and 740 krm, mean size (.x,,,) 163, 506 and 1068 pm exponent ((k) 1.42. 2.31 and 0.84, and participation to the whole mass with (p) 49, 23 and 28”/0, respectively. The fine population originates, according to the ‘two phase model of coal’, from the mineral. the coarse, from the maceral pseudo-phase, while the middle fraction is presumably formed from extraneous minerals. Other three samples taken from the same power plant 20 years later could be resolved alike in three populations, with .Q and I, shifted to smaller sizes. Concentrations of Na and Ca are evenly distributed amona size classes, concentrations of K, Mg, I, Fe. Ti and P are decreasing with particle size, while the concentratio of S and C increases from the smallest to the largest size class 5 an IO times, $ respectively, due to the mainly organic origin of these elem’ents. 02/00901 Improvement of environmental quality of coal fly ash by applying forced leaching Nugteren, H.W. 01 rrl. Furl, 2001, 80, (6), 873-877. A coal fly ash containing leachable trace elements in amounts higher than allowed by Dutch law for its free application as granular building material was subjected to forced leaching using water, citrate-, oxalate-, EDTA- and carbonate-solutions. With water only, the free lime and substantial amounts of MO (30%), Se (20-40%) and SO4’ (40-50%) are removed. Using the extraction agents, these percentages increase to 60-90% and in addition 15-20% Cr, V and Sb are removed. The environmental quality of the washed fly ash was checked with the Dutch standard leaching test (NEN7343). Leachability of MO, Se and S decreased by a factor of 2-4 after washing with water and a factor 2-18 including Cr) after washing with the extracting agents. Removing extractants and metals remaining in the moisture after filtration will further decrease leaching, For a feasible process reduction of reagent consumption and simple methods for process-water recycling are needed. 02100902 Method for treating wastewater and sewage with fly ash Zhang, Y. Faming Zhuanli Shenqing Gongkai Shuomingshu CN 1,273,944 (Cl. C02F1/28), 22 Nov 2000, Appl. 99,114,215, 15 May 1999. 8. (In Chinese) The method comprises percolating wastewater and sewage through fly ash layer outdoor on site in electricity generating plant, collecting the wastewater in water-collecting construction with gravel layer, and discharging. The percolation speed of the wastewater is controlled at SO.06 m h ’ by adjusting the discharging speed of water from watercollecting construction. The thickness of the fly ash layer is 21.5 m, and that of the gravel layer is 0.5-1.5 m. 02/00903 Micro- and nanostructure of the carbon matrix of infiltrated carbon fiber felts Reznik, B. PI al. C&on, 2001, 39. (2), 215-229. The structural properties of carbon/carbon-composites fabricated by chemical vapour infiltration (CVI) were studied by polarized light microscopy (PLM), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) on a micrometer and nanometer scale. The types of carbon bonds were estimated by electrqn-energyloss spectroscopy (EELS). Using a methane/hydrogen gas mixture at a temperature of 1lOOAC two different methane partial pressures were applied. The carbon fibres are surrounded by ring-shaped layers with different optical reflectance. The SEM analyses of fracture surfaces revealed differences in the micromechanical behaviour depending on the matrix morphology. Particular emphasis was put on the distinction of individual forms of pyrolytic carbons with similar optical behaviour, which reveals significant structural differences in detailed SEM and TEM analyses. 02/00904 Optimization of conditions for the preparation of activated carbons from olive-waste cakes Baqaoui, A. L’I(I/. Carbon, 2001, 39. (3), 425-432. An experimental design (Doehlert matrix) has been drawn up to optimize the experimental conditions of the preparation of activated carbon from olive-waste cakes. A series of activated carbons have been prepared by physical activation with steam. Adsorption of NZ (77 K), CO? (273 K) and mercury porosimetry experiments have been carried out to determine the characteristics of all carbons prepared. Adsorption of iodine and methylene blue was used as a primary indicator of 110
Fuel and Energy Abstracts
March 2002
the adsorption capacity of these carbons. The experimental response varied between: 13-27% for the total yield (Y,), I IS-490 mg/g for the adsorption of methylene blue (Yz), 741-1495 mg/g for the adsorption of iodine (Yj), 514-1271 m’/g for the BET surface area ( Y4), 0.2250.377 cm’/g for the micropore volume (Ys), 0.2174.557 cm’/g for the volume of pores with a diameter greater than 3.7 nm (Y,) and 31.3-132 m*/g for the external surface area (Y,). The results obtained were exploited using response surface methodology. These responses have been represented and studied in all experimental regions of activation time and activation temperature, the most influential factors in activated carbon preparation. Optimization to obtain activated carbons with textural characteristics suitable to use in water treatment has been carried out. The optimal activated carbon is obtained when using 68 min as activation time and 1095 K as activation temperature. 02/00905 Pilot scale study of trace element vaporization and condensation during combustion of a pulverized subbituminous coal Senior, C.L. ef rrl. Fuel Processing TcchnologJt, 2000, 63, (2-3), 149-165. Trace metal emissions from coal-fired power plants are largely associated with the fly ash. The work reported here is part of a larger effort to develop a fundamental modei for transformation of trace metals in coal to air toxic emissions from coal-fired power plants. Because the time-temperature history of the combustion gases determines the condensation behaviour of gaseous species, experimental study of these phenomena require a realistic post-combustion environment. Pilot-scale combustion of a Powder River Basin coal was conducted using realistic post-combustion conditions. Trace element distributions were measured in the submicron fly ash at the inlet to an electrostatic precipitator. Flame temperature had a dramatic impact on the amount of certain trace elements such as As and Se in the submicron ash, indicating that these elements vaporize during the combustion process. The amount of vaporization was not sensitive to coal grind. There is evidence for the reaction of As and Se vapours with the large (supermicron) ash in the post-combustion flue gas via a surface reaction. The correlation between arsenic and calcium in the ash suggests the formation of calcium arsenate. No such correlation was observed between selenium and calcium. 02/00906 Preparation of activated carbons from corn cob catalyzed by potassium salts and subsequent gasification with COP Tsai, W.T. e! ul. Biore.sorrr. Techno/., 2001, 78, (2), Preparation of activated carbons from corn cob catalysed by potassium salts and subsequent gasification with COz 02/00907 Preparation of activated carbons from Spanish anthracite. I. Activation by KOH. Lozano-Castello, D. et rrl. Carbon, 2001, 39, (5), 741-749. In the present paper, the effect of different preparation variables, e.g. KOH/anthracite ratio, heating rate, carbonization temperatures, and carbonization time, on the final porous texture is discussed. Among those different variables studied, the KOH/anthracite ratio seems to be the most important one. In addition, this study introduces an investigation of the introgen flow rate, showing that this variable has a very important effect on porosity development. The study confirms that the raw material used is appropriate for the preparation of activated carbons in a single stage pyrolysis process. The proper choice of the preparation conditions allows us to. produce microporous activated carbons with a micropore volume up to I.45 cm3/g and a BET surface area of 3290 m’/g. 02/00908 Preparation of binder pitches by blending coaltar and petroleum pitches Perez, M. cr ul. Ligh/ Met. (Wurrmdcde, PA, U. S.), 2001, 573-579. This paper deals with the preparation and characterization of blends obtained by physical mixing a combined binder coal-tar pitch and two selected petroleum pitches in different proportions. The results show that there are no chemical interactions between the coal-tar and petroleum pitch components at the blending stage, although wettability is substantially improved. However, considerable interactions can be observed between the pitch components when the blends are carbonized, These interactions affect weight loss, mesophase development and the optical texture of the pitch cokes. Coal-tar pitch shortens the temperature range of petroleum pitch weight loss, restricts the ability of the petroleum pitch to generate mesophase and improves the microstrength of the cokes. 02/00909 Preparation of porous carbon films by the pyrolysis of poly(urethane-imide) films and their pore characteristics Takeichi, T. el ul. Crrrhon, 2001, 39, (2), 257-265. Porous carbon films were prepared by the pyrolysis of poly(urethaneimide) films that were prepared by a reaction between phenolterminated polyurethane prepolymer and poly(amide acid) obtained
related to fuels
In India fly ash management is nearly 73% of the total installed power generation capacity, of which most is coal-based generation. Topics discussed include fly ash utilization trends in India, and issues on ash handling, ash pond management, ash utilization and facilitation for the 21st century. 02/00900 Grain size distribution of lsalnita power plant lignite ash and elemental composition of size classes Niac, G. e! cl/. F~,cJ/,2001, 80, (5). 731-737. Grain size analysis of 48 samples of Isalni(a power plant lignite ash revealed a mixture of three populations, each of them showing best fit to Weibull distribution with smallest size (.x~) 40, 350 and 740 krm, mean size (.x,,,) 163, 506 and 1068 pm exponent ((k) 1.42. 2.31 and 0.84, and participation to the whole mass with (p) 49, 23 and 28”/0, respectively. The fine population originates, according to the ‘two phase model of coal’, from the mineral. the coarse, from the maceral pseudo-phase, while the middle fraction is presumably formed from extraneous minerals. Other three samples taken from the same power plant 20 years later could be resolved alike in three populations, with .Q and I, shifted to smaller sizes. Concentrations of Na and Ca are evenly distributed amona size classes, concentrations of K, Mg, I, Fe. Ti and P are decreasing with particle size, while the concentratio of S and C increases from the smallest to the largest size class 5 an IO times, $ respectively, due to the mainly organic origin of these elem’ents. 02/00901 Improvement of environmental quality of coal fly ash by applying forced leaching Nugteren, H.W. 01 rrl. Furl, 2001, 80, (6), 873-877. A coal fly ash containing leachable trace elements in amounts higher than allowed by Dutch law for its free application as granular building material was subjected to forced leaching using water, citrate-, oxalate-, EDTA- and carbonate-solutions. With water only, the free lime and substantial amounts of MO (30%), Se (20-40%) and SO4’ (40-50%) are removed. Using the extraction agents, these percentages increase to 60-90% and in addition 15-20% Cr, V and Sb are removed. The environmental quality of the washed fly ash was checked with the Dutch standard leaching test (NEN7343). Leachability of MO, Se and S decreased by a factor of 2-4 after washing with water and a factor 2-18 including Cr) after washing with the extracting agents. Removing extractants and metals remaining in the moisture after filtration will further decrease leaching, For a feasible process reduction of reagent consumption and simple methods for process-water recycling are needed. 02100902 Method for treating wastewater and sewage with fly ash Zhang, Y. Faming Zhuanli Shenqing Gongkai Shuomingshu CN 1,273,944 (Cl. C02F1/28), 22 Nov 2000, Appl. 99,114,215, 15 May 1999. 8. (In Chinese) The method comprises percolating wastewater and sewage through fly ash layer outdoor on site in electricity generating plant, collecting the wastewater in water-collecting construction with gravel layer, and discharging. The percolation speed of the wastewater is controlled at SO.06 m h ’ by adjusting the discharging speed of water from watercollecting construction. The thickness of the fly ash layer is 21.5 m, and that of the gravel layer is 0.5-1.5 m. 02/00903 Micro- and nanostructure of the carbon matrix of infiltrated carbon fiber felts Reznik, B. PI al. C&on, 2001, 39. (2), 215-229. The structural properties of carbon/carbon-composites fabricated by chemical vapour infiltration (CVI) were studied by polarized light microscopy (PLM), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) on a micrometer and nanometer scale. The types of carbon bonds were estimated by electrqn-energyloss spectroscopy (EELS). Using a methane/hydrogen gas mixture at a temperature of 1lOOAC two different methane partial pressures were applied. The carbon fibres are surrounded by ring-shaped layers with different optical reflectance. The SEM analyses of fracture surfaces revealed differences in the micromechanical behaviour depending on the matrix morphology. Particular emphasis was put on the distinction of individual forms of pyrolytic carbons with similar optical behaviour, which reveals significant structural differences in detailed SEM and TEM analyses. 02/00904 Optimization of conditions for the preparation of activated carbons from olive-waste cakes Baqaoui, A. L’I(I/. Carbon, 2001, 39. (3), 425-432. An experimental design (Doehlert matrix) has been drawn up to optimize the experimental conditions of the preparation of activated carbon from olive-waste cakes. A series of activated carbons have been prepared by physical activation with steam. Adsorption of NZ (77 K), CO? (273 K) and mercury porosimetry experiments have been carried out to determine the characteristics of all carbons prepared. Adsorption of iodine and methylene blue was used as a primary indicator of 110
Fuel and Energy Abstracts
March 2002
the adsorption capacity of these carbons. The experimental response varied between: 13-27% for the total yield (Y,), I IS-490 mg/g for the adsorption of methylene blue (Yz), 741-1495 mg/g for the adsorption of iodine (Yj), 514-1271 m’/g for the BET surface area ( Y4), 0.2250.377 cm’/g for the micropore volume (Ys), 0.2174.557 cm’/g for the volume of pores with a diameter greater than 3.7 nm (Y,) and 31.3-132 m*/g for the external surface area (Y,). The results obtained were exploited using response surface methodology. These responses have been represented and studied in all experimental regions of activation time and activation temperature, the most influential factors in activated carbon preparation. Optimization to obtain activated carbons with textural characteristics suitable to use in water treatment has been carried out. The optimal activated carbon is obtained when using 68 min as activation time and 1095 K as activation temperature. 02/00905 Pilot scale study of trace element vaporization and condensation during combustion of a pulverized subbituminous coal Senior, C.L. ef rrl. Fuel Processing TcchnologJt, 2000, 63, (2-3), 149-165. Trace metal emissions from coal-fired power plants are largely associated with the fly ash. The work reported here is part of a larger effort to develop a fundamental modei for transformation of trace metals in coal to air toxic emissions from coal-fired power plants. Because the time-temperature history of the combustion gases determines the condensation behaviour of gaseous species, experimental study of these phenomena require a realistic post-combustion environment. Pilot-scale combustion of a Powder River Basin coal was conducted using realistic post-combustion conditions. Trace element distributions were measured in the submicron fly ash at the inlet to an electrostatic precipitator. Flame temperature had a dramatic impact on the amount of certain trace elements such as As and Se in the submicron ash, indicating that these elements vaporize during the combustion process. The amount of vaporization was not sensitive to coal grind. There is evidence for the reaction of As and Se vapours with the large (supermicron) ash in the post-combustion flue gas via a surface reaction. The correlation between arsenic and calcium in the ash suggests the formation of calcium arsenate. No such correlation was observed between selenium and calcium. 02/00906 Preparation of activated carbons from corn cob catalyzed by potassium salts and subsequent gasification with COP Tsai, W.T. e! ul. Biore.sorrr. Techno/., 2001, 78, (2), Preparation of activated carbons from corn cob catalysed by potassium salts and subsequent gasification with COz 02/00907 Preparation of activated carbons from Spanish anthracite. I. Activation by KOH. Lozano-Castello, D. et rrl. Carbon, 2001, 39, (5), 741-749. In the present paper, the effect of different preparation variables, e.g. KOH/anthracite ratio, heating rate, carbonization temperatures, and carbonization time, on the final porous texture is discussed. Among those different variables studied, the KOH/anthracite ratio seems to be the most important one. In addition, this study introduces an investigation of the introgen flow rate, showing that this variable has a very important effect on porosity development. The study confirms that the raw material used is appropriate for the preparation of activated carbons in a single stage pyrolysis process. The proper choice of the preparation conditions allows us to. produce microporous activated carbons with a micropore volume up to I.45 cm3/g and a BET surface area of 3290 m’/g. 02/00908 Preparation of binder pitches by blending coaltar and petroleum pitches Perez, M. cr ul. Ligh/ Met. (Wurrmdcde, PA, U. S.), 2001, 573-579. This paper deals with the preparation and characterization of blends obtained by physical mixing a combined binder coal-tar pitch and two selected petroleum pitches in different proportions. The results show that there are no chemical interactions between the coal-tar and petroleum pitch components at the blending stage, although wettability is substantially improved. However, considerable interactions can be observed between the pitch components when the blends are carbonized, These interactions affect weight loss, mesophase development and the optical texture of the pitch cokes. Coal-tar pitch shortens the temperature range of petroleum pitch weight loss, restricts the ability of the petroleum pitch to generate mesophase and improves the microstrength of the cokes. 02/00909 Preparation of porous carbon films by the pyrolysis of poly(urethane-imide) films and their pore characteristics Takeichi, T. el ul. Crrrhon, 2001, 39, (2), 257-265. Porous carbon films were prepared by the pyrolysis of poly(urethaneimide) films that were prepared by a reaction between phenolterminated polyurethane prepolymer and poly(amide acid) obtained