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CO Selective Oxidation in Hydrogen-Rich Gas over Copper-Series Catalysts
The performances of CO selective oxidation in hydrogen-rich gas over four catalytic systems of CuO/ZrO2, CuO/MnO2, CuO/CoO and CuO/CeO2 were compared. The reducibility of these catalysts and the effect of CuO and CeO2 molar ratio of CuO/CeO2 catalysts on the activity of selective CO oxidation are investigated by XRD and TPR methods. The results show that the catalysts with the exception of CuO/ZrO2 have the interactions between CuO and CoO, CeO2 or MnO2, which result in a decrease in the reduction temperature. Among the catalysts studied, CuO/ZrO2 catalyst shows the lowest catalytic activity while CuO/CeO2 catalyst exhibits the best catalytic performance. The CuO(10%)/CeO2 catalyst attains the highest CO conversion and selectivity at 140 and 160 ℃. The addition of 9% H2O in the reactant feed decreases the activity of CuO/CeO2 catalyst but increases its CO selectivity....
2020-09-15 12:28:59浏览：58
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Gas Bench Ⅱ-IRMS测定地下水中溴同位素新技术
建立了利用Gas BenchⅡ联用同位素比值质谱仪(Gas BenchⅡ-IRMS)用于测定地下水中溴稳定同位素的方法.基于溴比氯更容易被重铬酸钾氧化的性质,将Br-氧化成Br2,而氯残留在原溶液中,从而把溴与氯分离开；再利用AgNO3将溴以AgBr的形式沉淀下来,然后将AgBr转化成CH3Br进行溴稳定同位素质谱测定.反应中,CH3I用量为20 μL,AgBr用量为0.5 mg.本测试流程需溴4～10 mg,质谱测试时间由1.5h缩短为800 s,测试精度优于±0.1‰(2σ).该方法可以用于地下水中溴同位素测定,在水文地质研究中具有广阔的应用前景....
2020-09-15 12:28:59浏览：76
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Effective and inexpensive gas chromatography method for detection of trace level SO2 in H2 fuel
Gas chromatography (GC) analysis of sulfer dioxide is challenging because SO2 is a highly mobile and chemically active molecule. For the conventional GC method with flame photometric detector (FPD) and direct-injection, it is often ineffective particularly when the SO2 level is as low as on the trace level. In this paper, a modified GC system integrated with an adsorption-desorption device was developed to detect the trace SO2 impurity in H2 fuel. Adsorbent GDX-502 is used in the adsorber to adsorb/collect SO2 from the sample gas and desorb/release it in a concentrated flow so that the conventional GC at downstream could detect it with an acceptable accuracy....
2020-09-15 12:28:59浏览：49
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Soft template synthesis of high selectivity mesoporous SnO2 gas sensors
Mesoporous SnO2 was synthesized using cetyltrimethyl ammonium bromide(CTAB)as supermolecule-template by hydrothermal method followed by calcining under different temperature in air.X-ray diffraction analysis(XRD)and transmission electron microscopy(TEM)techniques were used to characterize the structure of mesoporous SnO2.The results indicated that the gas sensors prepared by using mesoporous SnO2 after calcination at 400℃ showed quick response and recovery to ethanol at 200℃.It was also found that the mesostructure SnO2 with small particle size had higher sensitivity and selectivity to C2H5OH than the SnO2 nanoparticles the particle size of which is 20 nm synthesized by sol-gel method....
2020-09-15 12:28:59浏览：64
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Experimental Study on Mechanical Properties of Gas Hydrate-Bearing Sediments Using Kaolin Clay
A triaxial system is designed with a temperature range from-20℃ to 25℃and a pressure range from 0 MPa to 30 MPa in order to improve the understanding of the mechanical properties of gas hydrate-bearing sediments.The mechanical properties of synthetic gas hydrate-bearing sediments(gas hydrate-kaolin clay mixture)were measured by using current experimental apparatus.The results indicate that:(1)the failure strength of gas hydrate-bearing sediments strongly depends on the temperature.The sediment's strength increases with the decreases of temperature.(2)The maximum deviator stress increases linearly with the confining pressure at a low-pressure stage.However,it fluctuates at a high-pressure stage.(3)Maximum deviator stress increases with increasing strain rate,whereas the strain-stress curve has no tremendous change until the axial strain reaches approximately 0.5%.(4)The internal friction angles of gas hydrate-bearing sediments are not sensitive to kaolin volume ratio.The cohesion shows a high kaolin volume ratio dependency....
2020-09-15 12:28:59浏览：99
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New evidence for the origin of natural gas in Ordos Basin from hydrocarbons of oil water
The chief aim of the present work is to investigate the controversy origin of natural gas in the Ordos Basin by using the hydrocarbons of oil water. New evidence has been found: There is relatively high content of light hydrocarbons and low content of heavy components in the hydrocarbons fraction of oil water in the middle gas field of the Majiagou Formation, Ordovician reservoir. The hydrocarbons of oil water in Well Shan 12 and Well Shan 78 have relatively high abundance of tricyclic terpane. Tricyclic terpane/hopane of the two samples are 1.48 and 0.36, respectively. They also show that pregnane and hompregnane are in relatively high abundance with lower hopane/sterane ratio. Pr/Ph is less than 2.0. These characteristics reflected the source input of marine carbonate sedimentary environment. In contrast, the hydrocarbon of Well Shan 81 is lack of tricyclic terpane series and pregnane. It has a high hopane/sterane ratio and Pr/Ph is 3.27. These parameters are typical character of terrestrial organic matter. Furthermore, the hydrocarbons of oil water in Well Shan 37 and Well Shan 34 is between the two typical situations. They have little content of tricyclic terpanes. They may be derived from a mixing source of marine carbonate and terrestrial organic matter input. Similarly, the maturity parameters approve this suggestion. The samples of Well Shan 12 and Well Shan 78 which derived from marine carbonate have relatively high maturity and samples derived from terrestrial organic matter have lower maturity. The maturity of the hydrocarbons of mixing source is between these two situations. The suggestion coincides with the geological background and source rocks distribution....
2020-09-15 12:28:59浏览：48
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Kinetic model of gas phase polymerization of 1,3-butadiene catalyzed by supported rare earth coordin
Gas phase polymerization of 1,3-butadiene (Bd) catalyzed by supported rare earth coordination system is studied and a new kinetic model is proposed. Four elementary reactions or processes: the process of exposure and activation of potential active catalytic center, propagation, deactivation and chain transfer reaction to alkyl aluminum, are considered in this model. Some important parameters, such as monomer-consuming rate, are well expressed as the functions of macroscopic polymerization conditions such as pressure, temperature, and duration. The model can simulate the whole polymerization procedure satisfactorily....
2020-09-15 12:28:59浏览：67
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The Genetic Mechanism and Model of Deep-Basin Gas Accumulation and Methods for Predicting the Favora
As a kind of abnormal natural gas formed with special mechanism, the deep-basin gas, accumulated in thelower parts of a basin or syncline and trapped by a tight reservoir, has such characteristics as gas-water inversion, abnormalpressure, continuous distribution and tremendous reserves. Being a geological product of the evolution of petroliferousbasins by the end of the middle-late stages, the formation of a deep-basin gas accumulation must meet four conditions, i.e.,continuous and sufficient gas supply, tight reservoirs in continuous distribution, good sealing caps and stable structures.The areas, where the expansion force of natural gas is smaller than the sum of the capillary force and the hydrostaticpressure within tight reservoirs, are favorable for forming deep-basin gas pools. The range delineated by the above twoforces corresponds to that of the deep-basin gas trap. Within the scope of the deep-basin gas trap, the balance relationshipbetween the amounts of ingoing and overflowing gases determines the gas-bearing area of the deep-basin gas pool. The gasvolume in regions with high porosity and high permeability is worth exploring under current technical conditions and it isequivalent to the practical resources (about 10%-20% of the deep-basin gas). Based on studies of deep-basin gasformation conditions, the theory of force balance and the equation of material balance, the favorable areas and gas-containing ranges, as well as possible gas-rich regions are preliminarily predicted in the deep-basin gas pools in the UpperPaleozoic He-8 segment of the Ordos basin....
2020-09-15 12:28:59浏览：52
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Dynamic simulation research on injection and withdrawal performance of underground salt cavern natur
Owing to perfect impermeability,dynamics stability,flexible and efficient operation mode and strong adjustment,underground salt cavern natural gas storage is especially adapted to be used for short-term dispatch.Based on characteristics of gas flow and heat transfer,dynamic mathematic models were built to simulate the injection and withdrawal performance of underground salt cavern gas storage.Temperature and pressure variations of natural gas in gas storage were simulated on the basis of building models during withdrawal operation, and factors affecting on the operation of gas storage were also analyzed.Therefore, these models can provide theoretic foundation and technology support for the design,building and operation of salt cavern gas storage....
2020-09-15 12:28:59浏览：64
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Effect of HCO3- concentration on CO2 corrosion in oil and gas fields
The effect of HCO3- concentration on CO2 corrosion was investigated by polarization measurement of potentiodynamic scans and weight-loss method. Under the conditions of high pressure and high temperature, the corrosion rate of steel X65 decreased with the increase of HCO3- concentration, while pH of solution increased. SEM, EDS, and XRD results of the corrosion scales indicated that the typical FeCO3 crystallite was found at low HCO3- concentration but Ca(Fe,Mg)(CO3)2 was found at high HCO3 concentration. Ca2+ and Mg2+ are precipitated preferential to Fe2+ at high pH value. Potentiodynamic polarization curves showed that the cathodic current density decreases with the increase of HCO3- concentration at low HCO3- concentration. When the HCO3- concentration reaches 0.126 mol/L, increasing HCO3 concentration promotes cathodic reactions. Anodic behavior is an active process at low HCO3- concentration and the anodic current density decreases with the increase of HCO3- concentration. An evident active-passive behavior is exhibited in anodic process at 0.126 mol/L HCO3-....
2020-09-15 12:28:59浏览：48
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Influences of different types of magnetic fields on HCFC-141b gas hydrate formation processes
In this study, visualizations and experiments are carried out on the influence of static and rotating magnetic fields on the characteristics of HCFC-141b gas hydrate formation, such as crystallization form, formation temperature and induction time. It has been found that a proper rotating magnetic field can considerably improve the low-pressure gas hydrate formation process,especially in increasing the formation temperature and shortening the induction time. The morphology of the gas hydrate formation appears rather complex and compact. However, a proper static magnetic field can make the gas hydrate crystal more organized, which will be benefit to heat transfer....
2020-09-15 12:28:59浏览：53
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Gas Chromatography Analysis of Resin and Fatty Acids from Laboratory Generated Bleach Plant Effluent
Laboratory generated spent bleached liquor from the chlorination, caustic extraction stage of mixed wood kraft pulp processing has been analyzed both qualitatively and quantitatively for various resin & fatty acids by using GC. A number of resin acids,saturated and unsaturated fatty acids, chloro fatty and resin acid have been detected and their concentrations are estimated. The results are compared with results on different agriculture residue/hardwood pulps, which were reported earlier. The concentrations of various compounds detected have also been compared with their reported LC50 values....
2020-09-15 12:28:59浏览：67
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Capillary gas chromatographic determination of dimethachlon residues in fresh tobacco leaves and cut
Simple procedures for extraction and chromatographic determination of dimethachlon residues in fresh tobacco leaves and cut-tobacco are described. The determination was carried out by capillary gas chromatography (GC) with electron capture detection (ECD) and confirmed by GC-MS. The mean recoveries and relative standard deviation (RSD) were 93.2%～112.9% and 3.5%～6.7%, respectively at levels ranging from 0.01 to 0.1 mg/kg. The limit of determination was 0.001 mg/kg. Tobacco samples in routine check were successfully analyzed using the proposed method....
2020-09-15 12:28:59浏览：58
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Effect of Operating Parameters on Composition of Dry Gas Obtained During Gasoline Cracking Process
The influence of operating parameters on ethylene content in dry gas obtained during catalytic cracking of gasoline was investigated in a pilot fixed fluidized bed reactor in the presence of the MMC-2 catalyst. The results have shown that the majority of dry gas was formed during the catalytic cracking reaction of gasoline, with a small proportion of dry gas being formed through the thermal cracking reaction of gasoline. The ethylene content in dry gas formed during the catalytic cracking reaction was higher than that in dry gas formed during the thermal cracking reaction. The ethylene content in dry gas formed during catalytic cracking of gasoline with a higher olefin content was higher than that in dry gas formed during catalytic cracking of gasoline with a lower olefln content, which meant that the higher the amount of carbonium ions was produced during the reaction, the higher the ethylene content in the dry gas would be. An increasing reaction temperature could increase the percentage of dry gas formed during thermal cracking reaction in total dry gas products, leading to decreased ethylene content in the dry gas. An increasing catalyst/oil ratio could be conducive to the catalytic cracking reactions taking place inside the zeolite Y, leading to a decreased ethylene content in the dry gas. A decreasing space velocity could be conducive to the catalytic cracking reactions taking place inside the shape-selective zeolite, leading to increased ethylene content in the dry gas....
2020-09-15 12:28:59浏览：57
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Numerical studies of hydrate dissociation and gas production behavior in porous media during depress
In this study,a numerical model is developed to investigate the hydrate dissociation and gas production in porous media by depressurization.A series of simulation runs are conducted to study the impacts of permeability characteristics,including permeability reduction exponent,absolute permeability,hydrate accumulation habits and hydrate saturation,sand average grain size and irreducible water saturation.The effects of the distribution of hydrate in porous media are examined by adapting conceptual models of hydrate accumulation habits into simulations to govern the evolution of permeability with hydrate decomposition,which is also compared with the conventional reservoir permeability model,i.e.Corey model.The simulations show that the hydrate dissociation rate increases with the decrease of permeability reduction exponent,hydrate saturation and the sand average grain size.Compared with the conceptual models of hydrate accumulation habits,our simulations indicate that Corey model overpredicts the gas production and the performance of hydrate coating models is superior to that of hydrate filling models in gas production,which behavior does follow by the order of capillary coating＞pore coating＞pore filling＞capillary filling.From the analysis of t1/2,some interesting results are suggested as follows:(1) there is a "switch" value (the "switch" absolute permeability) for laboratory-scale hydrate dissociation in porous media,the absolute permeability has almost no influence on the gas production behavior when the permeability exceeds the "switch" value.In this study,the "switch" value of absolute permeability can be estimated to be between 10 and 50 md.(2) An optimum value of initial effective water saturation Sw,e exists where hydrate dissociation rate reaches the maximum and the optimum value largely coincides with the value of irreducible water saturation Swr,e.For the case of Sw,e＜Swr,e,or Sw,e＞Swr,e,there are different control mechanisms dominating the process of hydrate dissociation and gas production....
2020-09-15 12:28:59浏览：63
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