共查询到20条相似文献,搜索用时 546 毫秒
1.
Sheth AC Sastry C Yeboah YD Xu Y Agarwal P 《Journal of the Air & Waste Management Association (1995)》2003,53(4):451-460
Catalyst recovery studies were conducted for gasified chars produced from steam gasification of Illinois #6 coal catalyzed with two different catalyst systems. A ternary (43.5 mol% Li2CO3-31.5 mol% Na2COr-25 mol% K2CO3) and a binary (29 mol% Na2CO3-71 mol% K2CO3) eutectic catalyst system were used for gasifying coal. Various extraction schemes, such as water extraction, H2SO4 extraction, and acetic acid extraction, were evaluated with respect to their extraction efficiencies. Effects of major process variables, such as solvent-to-char ratio, mixing time, temperature, and concentration, on the extraction efficiency were evaluated. A process schematic for the entire catalyst recovery, regeneration, and recycle scheme was developed and the preliminary process economics were determined based on these extraction schemes. H2SO4 extraction was found to be the most desirable. It also turned out to be more attractive than a once-through throwaway system. 相似文献
2.
Menglei Zhang Hao Song Zhenglong Lin Yi Liu Weihong Wu 《Journal of the Air & Waste Management Association (1995)》2020,70(10):971-979
ABSTRACT Disposal of spent catalyst in an economical and green way has become a great concern for industrial production. We developed a process including acid leaching, solvent extraction and stripping in order to recycle spent catalyst. In this study, we conducted selective recovery of molybdenum through focus on finding an optimized extraction and stripping process by comparing different extractants and stripping agents. To separate molybdenum from other metals efficiently and figure out the mechanism of extraction process, the five different extractants of methyl trioctyl ammonium chloride, tri-n-octylamine, tris (2-ethylhexyl) amine, bis (2-ethylhexyl) phosphate, and tributyl phosphate with different functional groups were examined; the extraction ability and extraction mechanism of these five extractants were systematically studied under the same system for the first time. It was found that more than 98% of the molybdenum could be extracted with an organic phase consisting of tri-n-octylamine or methyl trioctyl ammonium chloride under the optimal conditions. The result indicated that the tri-n-octylamine and methyl trioctyl ammonium chloride possess excellent molybdenum extraction ability, the extraction capacity of the rest extractants was in the order of bis (2-ethylhexyl) phosphate > tris (2-ethylhexyl) amine > tributyl phosphate. In the stripping process, NH4OH, NaOH, and H2SO4 were chosen as stripping agent to strip the molybdenum from the loaded tri-n-octylamine organic phase. The stripping ability of the three studied stripping agents was in the order NaOH > NH4OH > H2SO4. The Fourier transform infrared (FTIR) spectra showed that the structure of the tri-n-octylamine organic phase was stable during the extraction and stripping process. Results showed that molybdenum could be highly and efficiently recovered by optimized extraction and stripping process. Implications: A series of different extractants and stripping agent have been systematically studied in order to compare their extraction and stripping ability under the same system. Based on the obtained results, an optimized extraction and stripping process was proposed to recycle molybdenum from spent catalyst efficiently. It is possible to dispose spent catalysts in an economic and environmental way by this developed metal recovery process. 相似文献
3.
直接使用有机过渡金属化合物二茂铁作为催化剂,研究了非均相Fenton反应中亚甲基蓝的降解,并考虑了实际排放的印染废水中存在的无机助剂,进一步分析了典型无机助剂CuSO4、NaCl、Na2CO3、Na2SO4、Na2S的存在对该非均相Fenton体系的影响,结果表明:直接使用二茂铁做催化剂反应120min后,亚甲基蓝的剩余率为0.6%,羟基自由基的表观生成率为83.4%。NaCl、Na2CO3、Na2SO4、Na2S的加入会阻碍反应的进行,而CuSO4的加入会促进反应的进行。 相似文献
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5.
Ketwalee Kositkanawuth Roja Haritha Gangupomu Brian H. Dennis Frederick M. MacDonnell Richard Billo 《Journal of the Air & Waste Management Association (1995)》2013,63(10):1182-1195
To increase U.S. petroleum energy independence, the University of Texas at Arlington (UT Arlington) has developed a direct coal liquefaction process which uses a hydrogenated solvent and a proprietary catalyst to convert lignite coal to crude oil. This sweet crude can be refined to form JP-8 military jet fuel, as well as other end products like gasoline and diesel. This paper presents an analysis of air pollutants resulting from using UT Arlington's liquefaction process to produce crude and then JP-8, compared with 2 alternative processes: conventional crude extraction and refining (CCER), and the Fischer-Tropsch process. For each of the 3 processes, air pollutant emissions through production of JP-8 fuel were considered, including emissions from upstream extraction/production, transportation, and conversion/refining. Air pollutants from the direct liquefaction process were measured using a LandTEC GEM2000 Plus, Draeger color detector tubes, OhioLumex RA-915 Light Hg Analyzer, and SRI 8610 gas chromatograph with thermal conductivity detector. According to the screening analysis presented here, producing jet fuel from UT Arlington crude results in lower levels of pollutants compared to international conventional crude extraction/refining. Compared to US domestic CCER, the UTA process emits lower levels of CO2-e, NOx, and Hg, and higher levels of CO and SO2. Emissions from the UT Arlington process for producing JP-8 are estimated to be lower than for the Fischer-Tropsch process for all pollutants, with the exception of CO2-e, which were high for the UT Arlington process due to nitrous oxide emissions from crude refining. When comparing emissions from conventional lignite combustion to produce electricity, versus UT Arlington coal liquefaction to make JP-8 and subsequent JP-8 transport, emissions from the UT Arlington process are estimated to be lower for all air pollutants, per MJ of power delivered to the end user.
Implications: The United States currently imports two-thirds of its crude oil, leaving its transportation system especially vulnerable to disruptions in international crude supplies. At current use rates, U.S. coal reserves (262 billion short tons, including 23 billion short tons lignite) would last 236 years. Accordingly, the University of Texas at Arlington (UT Arlington) has developed a process that converts lignite to crude oil, at about half the cost of regular crude. According to the screening analysis presented here, producing jet fuel from UT Arlington crude generates lower levels of pollutants compared to international conventional crude extraction/refining (CCER). 相似文献
6.
《Atmospheric environment (Oxford, England : 1994)》2007,41(7):1426-1439
This paper focuses on a detailed analysis of the effects of meteorological factors explaining the variability of rain composition.Inorganic composition of 113 individual rain events was measured from May 2002 to October 2005 at a rural site near Chimay, in the western part of the Belgian Ardennes. Original models were fitted for each studied ion (H+, Mg2+, Ca2+, K+, NH4+, Na+, Cl−, NO3− and SO42−) to relate rain event concentration or wet deposition to the rainfall volume (R), the length of the antecedent dry period (ADP), the volume of the previous event (Rprev) as well as to the mean wind speed and the prevailing wind direction during both the dry and the rainy periods. These variables explained from 32% (H+) to 69% (NO3−) of rain concentration variability. Concentrations decreased logarithmically with increasing R values except in case of H+ for which a positive effect of rain volume on rain concentration was observed. ADP affected positively rain concentrations of all ions excluding K+ and H+ for which, respectively, a nonsignificant and a negative effect of this variable was observed. Increasing Rprev strengthened the effect of the variable R on H+, Mg2+, Ca2+, Na+, NH4+ and SO42− concentrations while it softened the effect of ADP on NO3− concentrations. Wind speed and direction during dry and rainy periods explained together from 8% (K+) to 38% (Na+) of rain concentration total variability. R2 coefficients of the wet deposition models ranged from 0.51 (K+) to 0.79 (SO42−). For all ions, wet deposition increased significantly with increasing R values while the effects of the other variables were similar to those on concentrations. Wind conditions during dry and rainy periods explained from 4% (H+) to 24% (Na+) of wet deposition total variability. On an annual scale, the total dry period duration, the total rainfall volume as well as the shape of the distributions of the length of the antecedent dry periods and of the rain event volume are important parameters that influence annual wet deposition. 相似文献
7.
Li Fang Xiaofang Duan Rongming Chen 《Journal of the Air & Waste Management Association (1995)》2014,64(8):887-893
This paper presents an effective utilization of slag from acid leaching of coal-waste with a novel approach, namely low-temperature co-melting method, for preparation of sodium silicate (Na2O·nSiO2) using slag from acid leaching of coal-waste as feedstock. It is very interesting that the co-melting reaction temperature of the mixture of Na2CO3 and the feedstock (50?100 μm) was as low as 850 °C, which was significantly lower than the temperature used in traditional sodium silicate production (1400 °C). The optimum SiO2/Na2O ratio was identified as 7:3 according to the results of thermogravimetry–differential scanning calorimetry (TGA-DSC), ICP-AES, and X-ray diffraction (XRD) analyses. In this condition, the main product was sodium disilicate (Na2O·2SiO2), with water solubility of 85.0%. More importantly, the impurities such as aluminum in the feedstock, which had adverse effect on subsequent treatment, were concentrated almost completely in the filter residue as insoluble sodium alumunosilicates, i.e., Na(Si2Al)O6·H2O. The lower co-melting temperature of this process demonstrates a significant energy-saving opportunity and thus a promising approach for highly effective utilization of coal-waste.
Implications:Recently, alumina extraction from coal-waste has been extensively investigated and industrial applied in China. However, the slag-containing silica generated from the acid leaching process of coal-waste led to a secondary pollution, which hindered large-scale production. The proposed low-temperature co-melting method for preparation of sodium silicate (Na2O·nSiO2) using slag from acid leaching of coal-waste as feedstock indicated that it is an efficient approach for the recovery of silica from the acid-leached slag of coal-waste with minimal environmental impact. 相似文献
8.
D. F. Adams R. K. Koppe W. N. Tuttle 《Journal of the Air & Waste Management Association (1995)》2013,63(1):31-33
The technique includes the use of two chromatographic columns in series to separate O2, N2, CO, CO2, H2O, H2S, SO2 and CH3SH. Column 1, containing Triton 45 on Chromosorb, separates H2O, H2S, SO2 and CH3SH. Column 2, packed with Molecular Sieve, separates O2, N2, CO and CO2. The conditions required to obtain adequate sensitivity and separation are discussed. 相似文献
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10.
Mindong Bai Zhitao Zhang Hong Leng Xiyao Bai Chengwu Yi 《Journal of the Air & Waste Management Association (1995)》2013,63(7):854-860
ABSTRACT This paper presents a technique for the complete, simultaneous decomposition of CO2, SO2, and NOx, as well as the simultaneous removal of fly ash by ultra-high voltage pulse activation. Ultra-high voltage narrow pulse is used to make the gases in the reactor become active molecules, which are then dissociated into nonpoisonous gas molecules and solid particles under the control of a directional reaction model. By using a sufficient charge and a strong electric field, the fly ash can be removed. It becomes the carrier of C and S, and its efficiency is 99.5%. Owing to the action of catalyst B (using Ni as the mother's body), the activation energy of CO2, SO2, and NOx gases is reduced in great magnitude, and their removal efficiency can reach 75~90% at normal pressure and 180 °C. 相似文献
11.
《Atmospheric environment (Oxford, England : 1994)》2002,36(31):4941-4949
Chemical surveys of snow were carried out in the upper reaches of the Kunnes River, a tributary of the Yili River in East Tienshan Mountains, China. Some surprisingly high values of sodium and potassium (K++Na+) ranging from 4.44 to 8.99 mg/l compared with other data from neighboring areas are detected. Moreover, some relative high values of SO42− with mean concentration 15.8 mg/l for new snow and 14.40 mg/l for deposited snow, ranging from 10.43 to 23.71 mg/l are also found. Therefore, it is inferred that the sodium and potassium (K++Na+) are in the forms of sulfate and that the sources of the sulfate are deserts and some dried lakes in Central Asia. It is also found that there is obviously spatial variation of ions such as K++Na+, Ca2+, SO42− and HCO3−. The concentrations of K++Na+ and SO42−, and that of Ca2+ and HCO3− have similar spatial pattern. The temporal pattern of ion concentration of new snow is considered to be mainly controlled by the depth and area of snow cover in the study area and in the areas to the west. 相似文献
12.
R.K. Srivastava C.A. Miller C. Erickson R. Jambhekar 《Journal of the Air & Waste Management Association (1995)》2013,63(6):750-762
Abstract Emissions of sulfur trioxide (SO3) are a key component of plume opacity and acid deposition. Consequently, these emissions need to be low enough to not cause opacity violations and acid deposition. Generally, a small fraction of sulfur (S) in coal is converted to SO3 in coal-fired combustion devices such as electric utility boilers. The emissions of SO3 from such a boiler depend on coal S content, combustion conditions, flue gas characteristics, and air pollution devices being used. It is well known that the catalyst used in the selective catalytic reduction (SCR) technology for nitrogen oxides control oxidizes a small fraction of sulfur dioxide in the flue gas to SO3. The extent of this oxidation depends on the catalyst formulation and SCR operating conditions. Gas-phase SO3 and sulfuric acid, on being quenched in plant equipment (e.g., air preheater and wet scrubber), result in fine acidic mist, which can cause increased plume opacity and undesirable emissions. Recently, such effects have been observed at plants firing high-S coal and equipped with SCR systems and wet scrubbers. This paper investigates the factors that affect acidic mist production in coal-fired electric utility boilers and discusses approaches for mitigating emission of this mist. 相似文献
13.
Robert B. Snyder W. Ira Wilson Irving Johnson Albert A. Jonke 《Journal of the Air & Waste Management Association (1995)》2013,63(10):975-981
The information presented in this paper is directed to engineers who are involved with environmental emissions from coal conversion plants. Synthetic sorbents were investigated as an alternative to natural sorbents (limestone) for the removal of SO2 from the combustion gas in a fluidized-bed coal combustor. The sulfation rate of a synthetic sorbent, CaO in α-AI2O3, was determined as a function of gas composition, temperature, and calcium concentration in the sorbent. The reaction was found to be diffusion-controlled above 850°C and kinetically controlled at lower temperatures. The physical characteristics of the support material have a major effect oh the sulfation kinetics. Porosity measurements indicated that supports containing large pores (>0.2 µm) produced sorbents having high sulfation rates and that pores with diameters less than 0.2 µm did not contribute significantly to the capture of SO2. The sorbents SrO in α-AI2O3 and BaO in α-AI2O3 had lower SO2 capture rates than did CaO in α-AI2O3. The alkali metal oxide sorbents K2O and Na2O in α-AI2O3 captured SO2 much faster than did the alkaline earth metal oxides. 相似文献
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15.
R.Q. Long R.T. Yang K.D. Zammit 《Journal of the Air & Waste Management Association (1995)》2013,63(3):436-442
ABSTRACT Fe3+-, Cr3+-, Cu2+-, Mn2+-, Co2+-, and Ni2+-exchanged Al2O3-pillared interlayer clay (PILC) or TiO2-PILC catalysts are investigated for the selective catalytic reduction (SCR) of nitric oxide by ammonia in the presence of excess oxygen. Fe3+-exchanged pillared clay is found to be the most active. The catalytic activity of Fe-TiO2-PILC could be further improved by the addition of a small amount of cerium ions or cerium oxide. H2O and SO2 increase both the activity and the product selectivity to N2. The maximum activity on the Ce-Fe-TiO2-PILC is more than 3 times as active as that on a vanadium catalyst. Moreover, compared to the V2O5-WO3/TiO2 catalyst, the Fe-TiO2-PILC catalysts show higher N2/N2O product selectivities and substantially lower activities (by ~85%) for SO2 oxidation to SO3 under the same reaction conditions. A 100-hr run in the presence of H2O and SO2 for the CeO2/Fe-TiO2-PILC catalyst showed no decrease in activity. 相似文献
16.
《Atmospheric environment (Oxford, England : 1994)》2002,36(11):1883-1894
This work presents a gas chromatographic method that uses a thermal conductivity detector (GC-TCD) to measure the liquid water mass (LWM) of collected aerosols. The method is a modification of the previously developed EA-TCD method (Journal of Aerosol Science 29, 827). A microcomputer was incorporated into the system to control the analytical procedures, improve the measurement precision, and make possible a continuous operation. To validate the method, the aerosol LWMs of NaCl, Na2SO4, NH4NO3, (NH4)2SO4, NH4Cl, and Na2CO3 were measured at room temperature under relative humidities (RHs) varying between 20% and 90%, in both humidifying and dehumidifying conditions. Estimates of aerosol LWMs for varying aerosol chemical compositions and RHs by various measurement methods and predictive models are comprehensively compared. The comparison shows that the GC-TCD measurements agree closely with those of the other methods. The GC-TCD measurements are closer to the ISORROPIA model predictions than those of the AIM2 model. Most notably, our method determines, for the first time, the hygroscopic behavior of Na2CO3 aerosol yielding the deliquescence relative humidity and crystallization relative humidity at 78% and 39% RH, respectively. The hygroscopic characteristics of various NaCl mole fractions in mixed NaCl–Na2SO4 aerosols, determined by GC-TCD, are used to show the discrepancy between the measurements and the model's prediction. 相似文献
17.
PM2.5 chemical source profiles for vehicle exhaust, vegetative burning, geological material, and coal burning in Northwestern Colorado during 1995 总被引:12,自引:0,他引:12
PM2.5 (particles with aerodynamic diameters less than 2.5 μm) chemical source profiles applicable to speciated emissions inventories and receptor model source apportionment are reported for geological material, motor vehicle exhaust, residential coal (RCC) and wood combustion (RWC), forest fires, geothermal hot springs; and coal-fired power generation units from northwestern Colorado during 1995. Fuels and combustion conditions are similar to those of other communities of the inland western US. Coal-fired power station profiles differed substantially between different units using similar coals, with the major difference being lack of selenium in emissions from the only unit that was equipped with a dry limestone sulfur dioxide (SO2) scrubber. SO2 abundances relative to fine particle mass emissions in power plant emissions were seven to nine times higher than hydrogen sulfide (H2S) abundances from geothermal springs, and one to two orders of magnitude higher than SO2 abundances in RCC emissions, implying that the SO2 abundance is an important marker for primary particle contributions of non-aged coal-fired power station contributions. The sum of organic and elemental carbon ranged from 1% to 10% of fine particle mass in coal-fired power plant emissions, from 5% to 10% in geological material, >50% in forest fire emissions, >60% in RWC emissions, and >95% in RCC and vehicle exhaust emissions. Water-soluble potassium (K+) was most abundant in vegetative burning profiles. K+/K ratios ranged from 0.1 in geological material profiles to 0.9 in vegetative burning emissions, confirming previous observations that soluble potassium is a good marker for vegetative burning. 相似文献
18.
Ionic composition of TSP and PM2.5 during dust storms and air pollution episodes at Xi'an,China 总被引:1,自引:0,他引:1
Zhenxing Shen Junji Cao Richard Arimoto Zhiwei Han Renjian Zhang Yuemei Han Suixin Liu Tomoaki Okuda Shunsuke Nakao Shigeru Tanaka 《Atmospheric environment (Oxford, England : 1994)》2009,43(18):2911-2918
TSP and PM2.5 samples were collected at Xi'an, China during dust storms (DSs) and several types of pollution events, including haze, biomass burning, and firework displays. Aerosol mass concentrations were up to 2 times higher during the particulate matter (PM) events than on normal days (NDs), and all types of PM led to decreased visibility. Water-soluble ions (Na+, NH4+, K+, Mg2+, Ca2+, F?, Cl?, NO3?, and SO42?). were major aerosol components during the pollution episodes, but their concentrations were lower during DSs. NH4+, K+, F?, Cl?, NO3?, and SO42? were more abundant in PM2.5 than TSP but the opposite was true for Mg2+ and Ca2+. PM collected on hazy days was enriched with secondary species (NH4+, NO3?, and SO42) while PM from straw combustion showed high K+ and Cl?. Firework displays caused increases in K+ and also enrichments of NO3? relative to SO42?. During DSs, the concentrations of secondary aerosol components were low, but Ca2+ was abundant. Ion balance calculations indicate that PM from haze and straw combustion was acidic while the DSs samples were alkaline and the fireworks' PM was close to neutral. Ion ratios (SO42?/K+, NO3?/SO42?, and Cl?/K+) proved effective as indicators for different pollution episodes. 相似文献
19.
Joseph M. Genco Harvey S. Rosenberg 《Journal of the Air & Waste Management Association (1995)》2013,63(10):989-990
Large quantities of nahcolite ore, a naturally occurring mineral containing between 70 and 90% sodium bicarbonate are known to occur in the Green River Formation of the Piceance Creek Basin of northwestern Colorado.1 Deposits occur in two major forms, as either bedded or disseminated ore. In the latter case, the host rock is oil shale, a dolomitic marlstone containing kerogen material. Bench and pilot scale studies have shown finely divided nahcolite ore to be an effective SO2 sorbent in baghouse filters.2 These studies form the basis of the nahcolite ore injection process as a means for controlling SO2 emissions to the environment.3 Although there have been published investigations of reactions of SO2 with Na2CO3and NaHCO3, 4 no reference could be found to a systematic study of nahcolite ore reacting with SO2. 相似文献
20.
Zhitao Zhang Mindi Bai Xiyao Bai Qiaoyuan Pan 《Journal of the Air & Waste Management Association (1995)》2013,63(6):10-815
Abstract The removal of sulfur dioxide (SO2) from simulated flue gases streams (N2/O2/H2O/SO2) was experimentally investigated using microgap discharge. In the experiment, the thinner dielectric layers of aluminum oxide (Al2O3) were used to form the microgap discharge. With this physical method, a high concentration of hydroxyl (OH·) radicals were produced using the ionization of O2 and H2O to further the conversion of SO2 into sulfuric acid (H2SO4) at 120° C in the absence of any catalysts and absorbents, which were captured with the electrostatic precipitator (ESP). As a result, the increase of discharge power and concentrations of O2 and H2O increased the production of OH· radicals resulting in enhanced removal of SO2 from gas streams. With the test and analysis, a number of H2SO4 droplets were produced in experiment. Therefore, a new method for removal of SO2 in semidry method without ammonia (NH3) additive was found. 相似文献