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1.
Sulphur/sulphate containing additives, such as elemental sulphur (S) and ammonium sulphate (NH4)2SO4), can be used for sulphation of KCl during biomass combustion. These additives convert KCl to an alkali sulphate and a more efficient sulphation is normally achieved for ammonium sulphate compared to sulphur. The presence of SO3 is thus of greater importance than that of SO2. Oxygen and volatile combustibles could also have an effect on the sulphation of gaseous KCl. This paper is based on results obtained during co-combustion of wood chips and straw pellets in a 12 MW circulating fluidised bed (CFB) boiler. Ammonium sulphate was injected at three positions in the boiler i.e. in the upper part of the combustion chamber, in the cyclone inlet, and in the cyclone. The sulphation of KCl was investigated at three air excess ratios (λ = 1.1, 1.2 and 1.4). Several measurement tools were applied including IACM (on-line measurements of gaseous alkali chlorides), deposit probes (chemical composition in deposits collected) and gas analysis. The position for injection of ammonium sulphate had a great impact on the sulphation efficiency for gaseous KCl at the different air excess ratios. There was also an effect of oxygen on the sulphation efficiency when injecting ammonium sulphate in the cyclone. Less gaseous KCl was reduced during air excess ratio λ = 1.1 compared to the higher air excess ratios. The optimal position and conditions for injection of ammonium sulphate were identified by measuring KCl with IACM. A correlation was observed between the sulphation of gaseous KCl and reduced chlorine content in the deposits. The experimental observations were evaluated using a detailed reaction mechanism. It was used to model the effect of volatile combustibles on the sulphation of gaseous KCl by SO3. The calculations supported the proposition that the presence of combustibles at the position of SO3 injection (i.e. AS) causes reduction of SO3 to SO2. 相似文献
2.
Thermal decomposition of (NH4)2SO4 in presence of Mn3O4 总被引:1,自引:0,他引:1
Liqun Mao Ali T-RaissiCunping Huang Nazim Z. Muradov 《International Journal of Hydrogen Energy》2011,36(10):5822-5827
The main objective of this work is to develop a hybrid water-splitting cycle that employs the photon component of sunlight for production of H2 and its thermal (i.e. IR) component for generating oxygen. In this paper, (NH4)2SO4 thermal decomposition in the presence of Mn3O4, as an oxygen evolving step, was systematically investigated using thermogravimetric/differential thermal analyses (TG/DTA), temperature programmed desorption (TPD) coupled with a mass spectrometer (MS), X-ray Diffraction (XRD), and X-ray Photoelectron Spectroscopy (XPS) techniques. Furthermore, thermolysis of ammonium sulfate, (NH4)2SO4, in the presence of Mn3O4 was also investigated by conducting flow reactor experiments. The experimental results obtained indicate that at 200-450 °C, (NH4)2SO4 decomposes forming NH3 and H2O and sulfur trioxide that in the presence of manganese oxide react to form manganese sulfate, MnSO4. At still higher temperatures (800∼900 °C), MnSO4 further decomposed forming SO2 and O2. 相似文献
3.
The catalytic hydroliquefaction of Xiaolongtan lignite (XL, a Chinese lignite) was investigated in a batch autoclave. The effects of reaction temperature, time and initial H2 pressure on the yields of gaseous and extractable portions (GEPs) were discussed. The catalytic activity of FeS+S was compared with that of FeS and SO42-/ZrO2, respectively. The results show that FeS+S is more active for XL hydroliquefaction than the other two catalysts and affords the highest gas and oil (G & O) yields in the three catalysts. The highest total yield of GEPs from XL hydroliquefaction gets to 90.0%, while total yield of G & O is 61.1% at 420 °C for 30 min over FeS+S. The assistant catalysis of the added sulfur was discussed. The structural features of asphaltenes and preasphaltenes were examined by elemental and FTIR analyses. 相似文献
4.
Isotopic composition of dissolved sulphate and hydrogen sulphide from some thermal springs of Sicily
Samples of some thermal springs from Sicily have been analysed for the isotopic composition of sulphur-bearing species. The values of δ34S(SO42− (range: +7.3, +31.7‰), δ34S(H2S) (range: −12.2, +27.8), δ34S(S°) (range: +1.9, +24.5) and δ18O(SO42−) (range: −2.5, +23.9) obtained show such a remarkable variability in data as to hypothesize different genetic processes concerning these species.Furthermore, from the available experimental data, the relationship between the isotopic composition of the sulphur in the dissolved sulphate and in the associated hydrogen sulphide (ΔSO42− - H2S = 25 – 30‰) seems to indicate the bacterial reduction of sulphate ion as one of the processes most significantly influencing the isotopic geochemistry of sulphur. 相似文献
5.
H. SchoemanH.M. Krieg A.J. KrugerA. Chromik K. KrajinovicJ. Kerres 《International Journal of Hydrogen Energy》2012,37(1):603-614
For hydrogen to become a serious contender for replacing fossil fuels, the manufacturing thereof has to be further investigated. One such process, the membrane based Hybrid Sulfur (HyS) process, where hydrogen is produced from the electrolysis of SO2, has received considerable interest recently. Since H2SO4 is formed during SO2 electrolysis, H2SO4 stability is a prerequisite for any membrane to be used in this process. In this study, pure as well as blended polybenzimidazole (PBI), partially fluorinated poly(arylene ether) (sFS) and nonfluorinated poly(arylene ethersulfone) (sPSU) membranes were investigated in terms of their acid stability as a function of acid concentration. Membranes were characterized using weight change, TGA, GPC, SEM/EDX and IEC. While a general stability was observed at 30 and 60 wt% H2SO4, the blended sFS-PBI and sPSU-PBI showed the highest stability throughout. According to the VI curve obtained for the SO2 electrolysis, the sPSU-PBI blend membrane performed slightly better than Nafion®117. 相似文献
6.
Huajun Zhang Yook Si Loo Hans Geerlings Jianyi Lin Wee Shong Chin 《International Journal of Hydrogen Energy》2010
Solid reactions between alkali aluminum hydrides (MAlH4, M = Li or Na) and NH4Cl (at mole ratio 1:1) at 170 °C were investigated quantitatively using temperature programmed reaction (TPR), thermo-gravimetric analysis (TGA), differential scanning calorimetry (DSC) and x-ray diffraction (XRD). The release of 3 mol of H2 from per mole of MAlH4 was measured, corresponding to 5.6 wt.% H2 capacity for the NaAlH4/NH4Cl system and 6.6 wt.% for LiAlH4/NH4Cl, respectively. By ball milling of the precursor compounds prior to the mixing, the reaction proceeded fast and NH3 production as the by-product could be avoided. The quick solid reactions may be attributed to the low melting temperatures of MAlH4 and the exothermic nature of the reactions. The reaction mechanism was also discussed. 相似文献
7.
Bin Liu Yong Shen Chua Guotao Wu Zhitao Xiong Ping Chen 《International Journal of Hydrogen Energy》2012
We report the synthesis of a new hydrogen storage material with a composition of LiCa(NH2)3(BH3)2. The theoretical hydrogen capacity of LiCa(NH2)3(BH3)2 is 9.85 wt.%. It can be prepared by ball milling the mixture of calcium amidoborane (Ca(NH2BH3)2) and lithium amide (LiNH2) in a molar ratio of 1:1. The experimental results show that this material starts to release hydrogen at a temperature as low as ca. 50 °C, which is ca. 70 °C lower than that of pure Ca(NH2BH3)2 possibly resulting from the active interaction of NH2− in LiNH2 with BH3 in Ca(NH2BH3)2. ca. 4.1 equiv. or 6.8 wt.% hydrogen can be released at 300 °C. The dehydrogenation is a mildly exothermic process forming stable nitride products. 相似文献
8.
Vapour/liquid fractionation of rare earth elements and yttrium (REY), Na+, K+, NH4+, HCO3−, SO42−, Cl− and borate in geothermal fluids from the Piancastagnaio geothermal field (Mt. Amiata geothermal area, Tuscany, central Italy) were evaluated based on the chemistry of collected liquids and condensed vapours. Apparent vapour–liquid partitioning factors (appDV/L) of REY vary from 0.3 to 0.01. These factors are much higher than those of Na (<0.001) and K (∼0.001). Volatile components are ion pairings such as NH4HCO3o, NH4Clo, NaHCO3o, CaSO4o and REYO(HCO)3o ⇔ REY(OH)CO3o. In vapour, REY and NH4+ are negatively correlated. High and low appDV/L(REY) indicate variations of NH4+ concentrations in liquids. The results of this study are relevant to the understanding of element migration and deposition under hydrothermal boiling conditions. 相似文献
9.
Tatsuo Noritake Kazutoshi Miwa Masakazu Aoki Mitsuru Matsumoto Shin-ichi Towata Hai-Wen Li Shin-ichi Orimo 《International Journal of Hydrogen Energy》2013
Complex hydride Mg(BH4)(NH2), which consists of double anion BH4− and NH2−, was synthesized and the crystal structure was analyzed by synchrotron X-ray diffraction. The mixture sample of Mg(BH4)2 + Mg(NH2)2 prepared by ball milling was reacted and crystallized to Mg(BH4)(NH2) by heating at about 453 K. This crystal phase transforms into amorphous phase above 473 K and subsequently the dehydrogenation begins. The crystal structure of Mg(BH4)(NH2) was determined from measurement data at 453 K (chemical formula: Mg0.94(BH4)1(NH2)0.88, crystal system: tetragonal, space group: I41 (No.80), Z = 8, lattice constants: a = 5.814(1), c = 20.450(4) Å at 453 K). Mg(BH4)(NH2) is ionic crystal which the cation (Mg2+) and the anions (BH4− and NH2−) are stacking alternately along the c-axis direction. Two BH4− and two NH2− tetrahedrally coordinate around Mg2+ ion. 相似文献
10.
Ki Yong Lee Hoon Sik Kim Chang Soo Kim Kwang-Deog Jung 《International Journal of Hydrogen Energy》2010
The solubility behavior of SO2 in 1-butyl-3-methylimidazolium acetate ([BMIm][OAc]) was investigated. The solubility of SO2 in [BMIm][OAc] was measured to be 0.6 in mole fraction at 50 °C in a stream of SO2 gas. The desorption of SO2 from [BMIm][OAc] was never completed, until the temperature was raised to 170 °C in a stream of N2, indicating that the absorption of SO2 is irreversible at the experimental condition. An in-situ IR study showed that acetate anion in [BMIm][OAc] transformed into acetic acid during the SO2 absorption. After removing acetic acid at 170 °C by evacuation, the bands at 1210, 1045 and 850 cm−1 appeared in IR spectra. The bands at 1210 and 1047 cm−1 were assigned to S–O stretching mode of HOSO2− (an isomer of HSO3−) and the band at 885 cm−1 was assigned to the symmetric stretching mode of HO–S. FT-IR study suggested that acetic acid and most plausibly [BMIm][HOSO2] were generated from the interactions of [BMIm][OAc] with SO2 and adventitious water in feed gas and/or [BMIm][OAc] during absorption–desorption process. [BMIm][HOSO2] recovered after removing acetic acid was found to be a new and reversible SO2 absorbent with the SO2 absorption capacity of 0.55 in mole fraction. 相似文献
11.
This article develops a least-cost optimization model in terms of the projected SO2 abatement costs of nine selected options for SO2 emissions control in the 10 most polluting power plants of the Mexican electrical sector (MES)—including SO2 scrubbing technologies, fuel oil hydrotreating desulphurization and fuel substitutions. The model not only finds the optimal combination of SO2 control options and generating units at 10% reduction intervals referred to the total SO2 emissions but also meets the restriction imposed in the NOM-085-ECOL-1994 (Mexican Official Norm) for allowable emission levels within critical zones. Similarly, two schemes are studied and analysed in this model: the first case considers the economical benefits derived from the substitution of fuel oil by imported low sulphur content coal in the Petacalco power plant and; the second case does not considered such economical benefits. Finally, results are obtained for these two cases in terms of the corresponding costs—investment, O&M, fuel—, abatement costs and the SO2 emissions reduction. 相似文献
12.
Sang-Kwon Lee Chang-Hee KimWon-Chul Cho Kyoung-Soo KangChu-Sik Park Ki-Kwang Bae 《International Journal of Hydrogen Energy》2009
The effect of Pt loading amount on SO2 oxidation reaction in an SO2-depolarized electrolyzer used in the hybrid sulfur (HyS) process for hydrogen generation was investigated by using transmission electron microscopy (TEM), cyclic voltammetry (CV), and linear sweep voltammetry (LSV). From the analysis of the CVs, it was found that the electrochemical active surface area increased as the Pt loading amount increased, while Pt utilization decreased. The CVs obtained in the SO2-free and SO2-saturated 50 wt.% H2SO4 solutions indicated that the chemical transformation of the adsorbed species to PtO at a higher potential creates passivation layers which partially cover the electrode surface and inhibit SO2 oxidation reaction. The LSVs revealed that the increase in Pt loading amount resulted in a considerable improvement of SO2 oxidation kinetics in a low potential region as compared with that in a high potential region. However, the area-specific activity for SO2 oxidation reaction decreased due to the reduction of Pt utilization. 相似文献
13.
The aim of this work is to investigate how SO2 can affect MCFC performance and to discover the possible mechanisms involved in cathode sulphur poisoning, specifically considering the possible use of MCFCs in CCS (Carbon Capture and Storage) application. The different contributions of cathodic, anodic and electrolyte reactions have been considered to get a complete picture of the evolution of performance degradation. Experimental tests have been performed at the Fuel Cell Centre laboratories of Korea Institute of Science and Technology (KIST) thanks to 100 cm2 single cell facilities and comparing results using both an optimized gas for laboratory conditions and a gas composition that simulates MCFCs when running in a Natural Gas Combined Cycle (NGCC) power plant. Polarisation curves, endurance tests, impedance measurements and gas analyses have been carried out to support the investigation. 相似文献
14.
Yongfeng Liu Ni Jian Zhuanghe Ren Jianjiang Hu Fang Du Mingxia Gao Hongge Pan 《International Journal of Hydrogen Energy》2018,43(30):13981-13989
A novel dual-cation/anion complex hydride (Li2Mg(BH4)2(NH2)2), which contains a theoretical hydrogen capacity of 12.1 wt%, is successfully synthesized for the first time by ball milling a mixture consisting of MgBH4NH2 and Li2BH4NH2. The prepared Li2Mg(BH4)2(NH2)2 crystallizes in a triclinic structure, and the [NH2] and [BH4] groups remain intact within the structure. Upon heating, the prepared Li2Mg(BH4)2(NH2)2 decomposes to release approximately 8.7 wt% hydrogen in a three-step reaction at 100–450 °C. In addition, a small amount of ammonia is evolved during the first and second thermal decomposition steps as a side product. This ammonia is responsible for the lower experimental dehydrogenation amount compared to the theoretical hydrogen capacity. The XRD and FTIR results reveal that Li2Mg(BH4)2(NH2)2 first decomposes to LiMgBN2, LiBH4, BN, LiH and MgBNH8 at 100–250 °C, and then, the newly formed MgBNH8 reacts with LiH to form Mg, LiBH4 and BN at 250–340 °C. Finally, the decomposition of LiBH4 releases hydrogen and generates LiH and B at 340–450 °C. 相似文献
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17.
Juan Zhao Bao-Xia Dong Yun-Lei Teng Lu Wang Chao Ping Zong-Wei Li 《International Journal of Hydrogen Energy》2018,43(10):5068-5076
Reactions between alkali metal hydrides MH (M = Li, Na, or K) and carbon dioxide (CO2) at room temperature were systematically investigated for the first time. It was found that the raw alkali metal hydrides did not react with CO2 under static-pressure conditions at room temperature, but the mechanically activated alkali metal hydrides reacted with CO2 and released large amounts of hydrogen (H2). Under the same ball-milling conditions, the order of reactivity of the alkali metal hydrides with CO2 was KH > NaH > LiH. The particle size of the activated alkali metal hydrides had a large influence on the reactivity of the alkali metal hydrides with CO2. During the reactions, CO2 was reduced by alkali metal hydrides, generating elemental carbon, alkali metal oxides and H2, and it was consumed by alkali metal oxides, forming carbonates. 相似文献
18.
Aysel Kantürk Figen Mehmet Burçin Pişkin Bilge Coşkuner Verda İmamoğlu 《International Journal of Hydrogen Energy》2013
In the present study, synthesis, structural characterization, and hydrolysis of the promising hydrogen storage carrier ammonia borane (NH3BH3), were investigated. NH3BH3 was prepared by one-pot chemical reaction between sodium borohydride (NaBH4) and different ammonia salts [NH4X, X: SO4, CO3, Cl] in the presence of solvent, tetrahydrofurane (THF). Synthesizes with different temperatures (20–40 °C), reaction times (30–130 min), amount of added THF volume (50–200 ml) and NaBH4/(NH4)2SO4 input molar ratios (0.47–0.75) were performed in order to find the optimum reaction conditions for obtaining maximum product yield. The characterization of NH3BH3 products was carried out by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy (RS), elemental analysis (C, H, N, O) and NMR spectroscopy. Characterization results indicated that NH3BH3 as a crystalline powder at 98% purity was achieved with 92.18% production yield. Additionally, hydrolysis of product NH3BH3 in the presence of amorphous Co–B catalyst at 22–80 °C under magnetic stirring (700 rpm) was performed. The maximum hydrogen generation rate was 5447.80 ml min−1 g cat−1 and the hydrolysis reaction kinetics were clarified based on zero-order, first-order and Langmuir–Hinshelwood kinetic models. 相似文献
19.
Retha Peach Henning M. Krieg Andries J. Krüger Derik van der Westhuizen Dmitri Bessarabov Jochen Kerres 《International Journal of Hydrogen Energy》2014
It has been shown that hydrogen, which can be used for energy storage, can be produced efficiently by the membrane based Hybrid Sulfur (HyS) process. During the HyS electrolysis step, SO2 and H2O are converted to H2 and H2SO4, which implies that membranes to be used for this process should have both a high proton conductivity and acid stability. In this study ionic and ionic-covalently cross-linked polybenzimidazole (PBI) blended membranes were investigated and compared with Nafion®212 in terms of their acid stability. Characterization of the membranes, which included monitoring the change in weight, swelling, SEM/EDX, TEM, TGA-MS, FTIR and IEC before and after H2SO4 treatment showed that all tested membranes were stable in 80 wt% H2SO4 at 80 °C for 120 h. Subsequent HyS electrolysis showed that the blend membranes performed better than Nafion®115 at current densities below 0.3 A/cm2, while performing similar above 0.3 A/cm2. 相似文献
20.
The SO2 transport properties of Nafion® and sPEEK membranes were measured using an electrochemical reaction cell to investigate their application in the electrochemical hybrid sulfur process. The permeability of SO2 in the membranes was determined from a combined theory based on Faraday's law and Fick's law where the electrochemical reaction rate of SO2 in the downstream membrane is the same as its diffusion flux through the membrane. Both Nafion® and sPEEK membranes show higher SO2 diffusion coefficients at higher temperatures. For sPEEK membranes, increasing the degree of sulfonation resulted in increasing permeability, as more water was imbibed in the membranes with higher degrees of sulfonation. Activation energy was extracted from the temperature-dependence of the diffusion coefficients for both membranes. The sPEEK membranes exhibited similar diffusion coefficients to those of Nafion®, even at high sulfonation degrees of 70%. Besides SO2 permeability, proton conductivity and mechanical properties were measured for comparison between the 2 polymer membranes. Although the proton conductivity of the sPEEK was slightly lower than the Nafion® membrane, it was very competitive considering its higher mechanical strength and much lower cost. 相似文献