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1.
The aim of present project was to develop a microcosm experimental method for estimation of NOx and CO2 emission of microbial origin from cultivated soil. The effect of different factors (such as temperature, water supply, mineral-N source and organic matter addition, role of soil organisms and heavy metal contamination) that controlling the accumulation of N2O and CO2 in soil atmosphere and release to air was studied in closed microcosm laboratory model experiments. The headspace gas composition of closed glass vessels of 800-1200 cm3 containing 100-200 g brown forest soil sample was analysed. The N2O and CO2 concentration of gas samples was analysed by gas chromatographic methods and NO-content by means of chemiluminescent detection. Concerning the results, it can be stated that the applied microcosm experimental model proved to be a suitable tool for detecting the effect of factors influencing the NOx and CO2 release from agricultural soil. The temporal changes of N2O and CO2 concentration demonstrated the impact of the coupled microbial processes resulting in these greenhouse gases. The gas production depended on the soil moisture level, temperature and C/N ratio significantly. The inhibitory effect of toxic heavy metals (e.g. Cd) could also be affected by the C/N ratio. The appearance of NO as an intermediate of microbial processes was observed as well. 相似文献
2.
Negoro Masaaki Shioji Norio Miyamoto Kazohisa Micira Yoshiharu 《Applied biochemistry and biotechnology》1991,(1):877-886
Growth and lipid production of microalgae were investigated, with attention to the feasibility of making use of flue gas CO2 as a carbon source. The effect of a high CO2 level in artificial seawater differed from strain to strain. Three algal strains from the Solar Energy Research Institute
(Golden, CO) collection were selected as good fixers of CO2 when the level of CO2 in the sparging gas was high. These algae also accumulated large amounts of crude lipids. SOX and NOX inhibited algal growth, but a green alga,Nannochloris sp. NANNO2 grew after a lag period, even when it received NO gas at the concentration of 300 ppm. 相似文献
3.
Gang Li Penny Xiao Paul Webley Jun Zhang Ranjeet Singh Marc Marshall 《Adsorption》2008,14(2-3):415-422
Capture of CO2 from flue gas streams using adsorption processes must deal with the prospect of high humidity streams containing bulk CO2 as well as other impurities such as SO
x
, NO
x
, etc. Most studies to date have ignored this aspect of CO2 capture. In this study, we have experimentally examined the capture of CO2 from a 12% synthetic flue gas stream at a relative humidity of 95% at 30 °C. A 13X adsorbent was used and the migration of
the water and its subsequent impact on capture performance was evaluated. Binary breakthrough of CO2/water vapor was performed and indicated a significant effect of water on CO2 adsorption capacity, as expected. Cyclic experiments indicate that the water zone migrates a quarter of the way into the
column and stabilizes its position so that CO2 capture is still possible although decreased. The formation of a water zone creates a “cold spot” which has implications
for the system performance. The recovery of CO2 dropped from 78.5% to 60% when moving from dry to wet flue gas while the productivity dropped by 22%. Although the concentration
of water leaving the bed under vacuum was 27%(vol), the low vacuum pressure prevented condensation of water in this stream.
However, the vacuum pump acted as a condenser and separator to remove bulk water. An important consequence of the presence
of a water zone was to elevate the vacuum level thereby reducing CO2 working capacity. Thus although there is a detrimental effect of water on CO2 capture, long term recovery of CO2 is still possible in a single VSA process. Pre-drying of the flue gas steam is not required. However, careful consideration
of the impact of water and accommodation thereof must be made particularly when the feed stream temperature increases resulting
in higher feed water concentration. 相似文献
4.
研究了以多孔二氧化硅微球和活性炭为载体制备NOx吸附/还原催化剂的方法,摸索了最佳Ce/Co物质的量的比例。采用低温氮吸附方法测定了样品的BET比表面和孔容,利用XRD方法表征了样品中所掺杂的金属元素的晶型。研究发现:当nCe/nCo=75/25时,材料获得最佳NOx吸附能力,当以多孔二氧化硅微球作载体时,材料对于NOx的吸附主要来自CoOx和CeO2的二元氧化物;当以活性炭作为载体时,活性炭参与了NOx的吸附,因此其吸附容量大大提高。对NOx的吸附机理进行了探讨,并研究了样品的NH3还原性质。 相似文献
5.
Biomimetic and microbial reduction of nitric oxide 总被引:1,自引:0,他引:1
Potter W. T. Le Uyen Ronda Suzanne Cho Jeong-Guk Shanmugasundram Ramesh Chirkis Allison Sublette Kerry L. 《Applied biochemistry and biotechnology》1995,(1):771-784
The biomimetic reduction of nitric oxide (NO) to nitrous oxide (N2O) by dithiothreitol in the presence of cyanocobalamin and cobaltcentered porphyrins has been investigated. Reactions were
monitored directly using Fourier Transform Infrared (FTIR) Spectroscopy vapor-phase spectra. Reaction rates were twofold faster
for the corrin than for the cobalt-centered porphyrins. The stoichiometry showed the loss of two molecules of NO per molecule
of N2O produced.
We have also demonstrated that the facultative anaerobe and chemoautotroph,Thiobacillus denitrificans, can be cultured anoxically in batch reactors using NO as a terminal electron acceptor with reduction to elemental nitrogen
(N2). We have proposed that the concentrated stream of NOx, as obtained from certain regenerable processes for the gas desulfurization and NOx removal, could be converted to N2 for disposal by contact with a culture ofT. denitrificans. Four heterotrophic bacteria have also been identified that may be grown in batch cultures with succinate, yeast extract,
or heat and alkali pretreated sewage sludge as carbon and energy sources and NO as a terminal electron acceptor. These areParacoccus dentrificans, Pseudomonas denitrificans, Alcaligens denitrificans, andThiophaera pantotropha. 相似文献
6.
氮氧化物(NOx)是一种重要的大气污染物, 它造成严重的环境问题, 同时威胁人类健康. 以钢铁烧结烟气为代表的固定源和以柴油机尾气为代表的移动源是氮氧化物的主要来源. 氨气选择性催化还原法(NH3-SCR)是目前最有效且应用最广泛的NOx脱除技术. 然而, 无论是固定源还是移动源上NH3-SCR催化剂, 都不可避免地会被SO2毒化, 造成催化剂失活, 限制了NH3-SCR技术的进一步应用. 因此, 研究NH3-SCR催化剂的SO2中毒机制以及提高催化剂的抗硫性能至关重要. 我们对固定源脱硝的金属氧化物和移动源上脱硝的Cu基分子筛这两类不同催化剂体系的SO2中毒机制的研究进展进行了介绍, 并对这两种催化剂上提高抗硫性能改性方法的研究进展进行了评述, 为未来的研究提供了参考. 相似文献
7.
Metal promoted zirconia-based oxide sorbents, such as Pt–ZrO2/Al2O3 for NO
x
have been investigated. To clarify the role of the catalyst component, sorption of NO and NO2 was compared using the samples with and without Pt. The catalytic oxidation of NO to NO2 and successively to nitrate ions is an important role for the Pt catalyst. The experimental results indicate that a high-temperature calcination is essential to remove residual Cl from Pt–ZrO2–Al2O3 prepared from H2PtCl6 in order to provide more active NO
x
sorption sites. Of M–ZrO2–Al2O3 samples investigated, ruthenium as well as Pt demonstrated relatively good performance as a catalyst component in the sorbent. The FT-IR spectra after sorption of NO and NO2 demonstrated a strong band attributed to stored nitrate ions. The Pt catalyst was more resistant to sulfur poisoning than a base metal catalyst. However, the NO
x
sorptive capacities of the Pt–ZrO2/Al2O3 sorbents were expected to be deteriorated in dilute SO2 as far as observed from FT-IR spectra. 相似文献
8.
An experimental study on the removal of NOx in a simulated vehicle exhaust gas has been carried out using point to plane and multipoint to plane DBD corona reactors. Hydrocarbon (C3H6) and NOx by-products were systematically investigated with a Gas Chromatography coupled to a Mass Spectrometry (GC/MS). NOx (NO and NO2) and CO output were also monitored with a gas analyzer in order to complete the mass balance. 18O tracer technique analyzes is applied to investigate the mechanism of propylene decomposition. From the plasma chemical reaction pathway proposed, it is apparent that the oxygen activation is one of the important steps for initiating the oxidation processes and the R-NOx formation. We present data for the reaction of the (N2/O2/C3H6/CO2NO/H2O system in the corona discharge reactors mentioned above. This system has been shown to generate a significant amount of aldehyde. CH3NO2 and CH3ONO2 are the main R-NOx compounds produced. Reactant composition and discharge energy densities (controlled by a numerical oscilloscope) were the operating parameters under study in wet and dry air mixture. Water vapors played an important role in NOx removal (especially in NO2 removal) via the reaction forming HNO3. Therefore, in wet-gas mixture supplied reactors the highest removal rates of NOx were as high as 30%, while in dry-gas only 15%. Different dielectric materials such as Al2O3/SiO2 and TiO2 on Al2O3/SiO2 support have been used. 相似文献
9.
In this paper, the NO-to-NO
2
conversion in various gaseous mixtures is experimentally investigated. Streamer coronas are produced with a dc-superimposed high-frequency ac power supply (10–60 kHz). According to NO
x
removal experiments in N
2
+NO
x
and N
2
+O
2
+NO
x
gaseous mixtures, it is supposed that the reverse reaction NO
2
+ONO+O
2
may not only limit NO
2
production in N
2
+NO
x
mixtures, but also increase the energy cost for NO removal. Oxygen could significantly suppress reduction reactions and enhance oxidation processes. The reduction reactions, such as N+NON
2
+O, induce negligible NO removal provided the O
2
concentration is larger than 3.6%. With adding H
2
O into the reactor, the produced NO
2
per unit removed NO can be significantly reduced due to NO
2
oxidation. NH
3
injection could also significantly decrease the produced NO
2
via NH and NH
2
- related reduction reactions. Almost 100% of NO
2
can be removed in gaseous mixtures of N
2
+O
2
+H
2
O+NO
2
with negligible NO production. 相似文献
10.
Lee Ju-No Lee Jin-Suk Shin Chul-Seung Park Soon-Chul Kim Seung-Wook 《Applied biochemistry and biotechnology》2000,84(1-9):329-342
Possible methods to minimize the toxic effects of SO
x
and NO
x
on the growth of a highly CO2 tolerant and fast-growing microalga, Chlorella sp. KR-1, were investigated. Maintaining the pH of the culturing media at an adequate value was quite important to enhancing
the tolerances of the microalgae to SO
x
and NO
x
. Controlling the pH by adding an alkaline solution, using a low flow rate of gas fed to the culture, and using a high concentration
of inoculating cells were effective methods to maintaining the proper pH of the culture. Controlling the pH was the most effective
method but could be applied only for some specific microalgae. 相似文献
11.
Masato Machida 《Catalysis Surveys from Japan》2002,5(2):91-102
(n)MnOx–(1–n)CeO2 binary oxides have been studied for the sorptive NO removal and subsequent reduction of NOx sorbed to N2 at low temperatures (150 °C). The solid solution with a fluorite-type structure was found to be effective for oxidative NO adsorption, which yielded nitrate (NO–
3) and/or nitrite (NO–
2) species on the surface depending on temperature, O2 concentration in the gas feed, and composition of the binary oxide (n). A surface reaction model was derived on the basis of XPS, TPD, and DRIFTS analyses. Redox of Mn accompanied by simultaneous oxygen equilibration between the surface and the gas phase promoted the oxidative NO adsorption. The reactivity of the adsorbed NOx toward H2 was examined for MnOx–CeO2 impregnated with Pd, which is known as a nonselective catalyst toward NO–H2 reaction in the presence of excess oxygen. The Pd/MnOx–CeO2 catalyst after saturated by the NO uptake could be regenerated by micropulse injections of H2 at 150 °C. Evidence was presented to show that the role of Pd is to generate reactive hydrogen atoms, which spillover onto the MnOx–CeO2 surface and reduce nitrite/nitrate adsorbing thereon. Because of the lower reducibility of nitrate and the competitive H2–O2 combustion, H2–NO reaction was suppressed to a certain extent in the presence of O2. Nevertheless, Pd/MnOx–CeO2 attained 65% NO-conversion in a steady stream of 0.08% NO, 2% H2, and 6% O2 in He at as low as 150 °C, compared to ca. 30% conversion for Pd/–Al2O3 at the same temperature. The combination of NOx-sorbing materials and H2-activation catalysts is expected to pave the way to development of novel NOx-sorbing catalysts for selective deNOx at very low temperatures. 相似文献
12.
Ogata Atsushi Mizuno Koichi Kushiyama Satoshi Yamamoto Toshiaki 《Plasma Chemistry and Plasma Processing》1998,18(3):363-373
The behavior of lattice oxygen species of the ferroelectric material during methane oxidation was investigated using a nonthermal plasma reactor packed with BaTiO
3
pellets. Lattice oxygen species in BaTiO
3
play an important role in the formation of N
2
O and the oxidation of CH
4
. The oxidation products such as CO and CO
2
were formed from independent reaction pathways. Lattice oxygen species were able to preferentially oxidize the carbon species deposited on the pellet surface into CO. Also, N
2
O and NO
x
were independently formed in the N
2–O
2
reaction, suggesting that different oxygen species give N
2
O and NO
x. N
2
O was produced by the oxidation of molecular nitrogen with lattice oxygen species. 相似文献
13.
Baeva M. Gier H. Pott A. Uhlenbusch J. Höschele J. Steinwandel J. 《Plasma Chemistry and Plasma Processing》2001,21(2):225-247
Pulsed microwave discharges operated at atmospheric pressure in gas mixtures containing N2, O2, and NO are investigated experimentally and theoretically for various gas mixture constituents and operating conditions with respect to the ability of exhaust gas purification. The rotational gas temperature and the vibrational temperature of N2 are derived from CARS measurements. The composition of the exhaust gas after treatment is monitored using FTIR spectroscopy. The processes of the chemical, electronic, and vibrational kinetics are described by a model that has been developed to calculate the species densities. The results obtained show that in N2/NO gas mixtures an overall reduction of NOx takes place. In the case of N2/O2/NO gas mixtures, no net reduction of NOx is achieved for a pulsed microwave power below 3600 W, a pulse length of 50 s, and a typical repetition frequency of 2 kHz. 相似文献
14.
Shanmugasundram Ramesh Lee Cheng-Ming Sublette Kerry L. 《Applied biochemistry and biotechnology》1993,(1):727-737
Two heterotrophic denitrifying bacteria,Paracoccus denitrificans andPseudomonas denitrificans, have been shown to utilize nitric oxide (NO) as a terminal electron acceptor and succinate, yeast extract, and heat/alkali
pretreated municipal sewage sludge as carbon and energy sources. Complete removal of NO (0.50%) from a feed gas sparged into
the cultures was observed. It is suggested that reduction of NO may be a common feature of denitrifying bacteria and that
a microbial process to dispose of NOx may be economically viable. 相似文献
15.
Moo Been Chang Mark J. Kushner Mark J. Rood 《Plasma Chemistry and Plasma Processing》1992,12(4):565-580
A gas-phase oxidation method using dielectric barrier discharges (DBDs) has been developed to remove SO2 and to simultaneously remove SO2 and NO from gas streams that are similar to gas streams generated by the combustion of fossil fuels. SO2 and NO removal efficiencies are evaluated as a function of applied voltage, temperature, and concentrations of SO2, NO, H2O(g), and NH3. With constant H2O(g) concentration, both SO2 and NO removal efficiencies increase with increasing temperature from 100 to 160°C. At 160°C with 15% by volume H20(g), more than 95% of the NO and 32% of the S02 are simultaneously removed from the gas stream. Injection of NH3 into the gas stream caused an increase in S02 removal efficiency to essentially 100%. These results indicate that DBD plasmas have the potential to simultaneously remove SO2 and NO from gas streams generated by large-scale fossil fuel combustors. 相似文献
16.
The aim of this work is to study the effect of Sr substitution on the redox properties and catalytic activity of La2−x
Sr
x
NiO4 (x = 0.0–1.2) for NO decomposition. Results suggest that the x = 0.6 sample shows the highest activity. The characterization (TPD, TPR, etc.) of samples indicates that the x = 0.6 sample possesses suitable abilities in both oxidation and reduction, which facilitates the proceeding of oxygen desorption
and NO adsorption. At temperature below 700°C, the oxygen desorption is difficult, and is the rate-determining step of NO
decomposition. With the increase of reaction temperature (T > 700°C), the oxygen desorption is favorable and, the active adsorption of NO on the active site (NO + V
o + Ni2+ → NO−-Ni3+) turns out to be the rate-determining step. The existence of oxygen vacancy is the prerequisite condition for NO decomposition,
but its quantity does not relate much to the activity.
Supported by the National Hi-Tech Research and Development Program of China (863 Program)(Grant No. 2004CB 719502) and the
National Natural Science Foundation of China (Grant No. 20177022) 相似文献
17.
臭氧氧化结合湿法喷淋对玻璃窑炉烟气同时脱硫脱硝实验研究 总被引:2,自引:0,他引:2
采用臭氧氧化结合湿法喷淋对模拟玻璃窑炉烟气开展了同时脱硫脱硝实验研究.采用不同溶液(NaOH、Na2S)进行了喷淋实验.结果表明,保证溶液pH值在10以上,NaOH浓度对NOx脱除效率无影响,SO2的存在促进了NOx吸收.当O3/NO物质的量比为1.6、溶液NaOH浓度为0.5%时,NOx脱除效率可达70%,SO2脱除效率在99%以上.往喷淋液中添加Na2S,NOx脱除效率随Na2S浓度增加而提高,SO2的存在对NOx脱除效率无影响.当O3/NO物质的量比为1.2、溶液中NaOH浓度为0.5%、添加剂Na2S浓度为0.6%时,NOx脱除效率可达70%,SO2脱除效率在95%以上.60 min长时间运行实验证明,模拟烟气中的NOx经碱液和添加剂吸收后主要以NO-2的形式存在于喷淋液中,且NOx脱除效率不随溶液pH值的变化而变化. 相似文献
18.
Di Bartolomeo Elisabetta Traversa Enrico Montanaro Laura Aono Hiromichi Sadaoka Yoshihiko 《Journal of Sol-Gel Science and Technology》2000,19(1-3):181-185
Sol-gel processed NASICON-type with new compositions in the Na3Zr2–(x/4)Si2–x
P1+x
O12 system showed an improved sinterability with an increase in the x value. This is attributed to liquid phase sintering. This dense electrolyte system is suitable for the application as gas sensors. The CO2 gas sensors using highly dense x = 0.667 (sample B) and x = 1.333 (sample C) samples show a stable EMF response in dry atmosphere which is very close to the theoretical value. Although a lower sensitivity and slower response were obtained in humid CO2 gas, the sensor performance recovered after switching from humid gas to dry gas. 相似文献
19.
Gas-Phase Removal of Acetaldehyde via Packed-Bed Dielectric Barrier Discharge Reactor 总被引:6,自引:0,他引:6
The effectiveness of applying packed-bed dielectric barrier discharge(PBDBD) technology for removing acetaldehyde from gas streams wasinvestigated. Operating parameters examined in this study include appliedvoltage, oxygen content, and gas-flow rate. Experimental results indicatethat the destruction efficiency of acetaldehyde predominantly depends onthe applied voltage. Removal of 99% of acetaldehyde has been achieved forgas streams containing 1000 ppmv acetaldehyde, 5% oxygen, with nitrogen asthe carrier gas. The oxygen content in the gas stream plays an importantrole in removing acetaldehyde within PBDBD. A higher CH3CHO removalefficiency is achieved for the gas stream containing less oxygen, since itwill dissipate energy due to its electronegative property. Carbon dioxideis the major end product, which is less hazardous to the environment and tohuman health. However, undesirable products, e.g., NO2 and N2O,CH3OC2H5, CH3COOH, CH3NO2,HCN, CH3NO3, and CH3OH, are detected as well. 相似文献
20.
利用溶剂热法合成了不同锂含量的MOF-5(xLi-MOF-5, x=0, 1, 3, 5).在MOF-5结晶过程中,锂离子被合并入其骨架结构中.实验表明,合并入骨架的锂能够改变MOF-5的结构和表面化学性质.不同的xLi-MOF-5能够不同程度降低骨架相互穿插的程度从而导致其吸附分离能力的大幅改变.其中,3Li-MOF-5具有最高的二氧化碳捕获能力(5.47 mmol·g-1),对40% CO2/60% CH4混合气体具有最优吸附选择性. 相似文献