Gaseous products generated by radiation degradation of N,N-diethylhydroxylamine aqueous solution

In this paper, gaseous products generated by radiation degradation of N,N-diethylhydroxylamine (DEHA)in aqueous solution are studied. The results show that by 10～1000 kGy irradiation of the solution in DEHA volume fraction of hydrogen did not change much with different concentrations of DEHA. The volume fraction of methane and ethane decreased, but that of ethene increased, with increasing DEHA concentration. The volume fraction of hydrogen, methane and ethane increased with the dose. The relationship of the volume fraction of ethene with the dose had something to do with the DEHA concentration.     

A Green Process for High-Concentration Ethylene and Hydrogen Production from Methane in a Plasma-Followed-by-Catalyst Reactor

A green process for the oxygen-free conversion of methane to high-concentration ethylene and hydrogen in a plasma-followed-by-catalyst （PFC） reactor is presented. Without any catalysts and with pure methane used as the feed gas, a stable kilohertz spark discharge leads to an acetylene yield of 64.1%, ethylene yield of 2.5% and hydrogen yield of 59.0% with 80.0% of methane conversion at a methane flow rate of 50 cm3 min-1 and a specific input energy of 38.4 kJ/L. In the effluent gas from a stable kilohertz spark discharge reactor, the concentrations of acetylene, ethylene and hydrogen were 18.1%, 0.7% and 66.9%, respectively. When catalysts Pd-Ag/SiO2 were employed in the second stage with discharge conditions same as in the case of plasma alone, the PFC reactor provides an ethylene yield of 52.1% and hydrogen yield of 43.4%. The concentrations of ethylene and hydrogen in the effluent gas from the PFC reactor were found to be as high as 17.1% and 62.6%, respectively. Moreover, no acetylene was detected in the effluent gas. This means that a high concentration of ethylene and oxygen-free hydrogen can be co-produced directly from methane in the PFC reactor.     

Comparison between Pulsed Cold Neutron Intensities from Liquid Hydrogen Moderator and from Solid Methane Moderator in Decoupling Type Moderator Assembly

Although liquid hydrogen is at present a unique cold moderator applicable to high intensity neutron sources, the reported pulsed cold neutron intensity from a liquid hydrogen moderator is significantly lower than that from a solid methane moderator. In this report, a reflected assembly with a thick hydrogen moderator is used to enhance the pulsed cold neutron intensity and the intensity is compared with that from a solid methane moderator. For comparison, 5 and 15 cm thick moderators were used for liquid hydrogen moderators. The thicker one was used to obtain the saturated intensity of pulsed cold neutrons. The thickness of a solid methane was 5 cm.

The cold neutron intensity from the 15 cm thick hydrogen moderator is about 1.6 times as high as that from the 5 cm one, in the case of the graphite reflected moderator assembly with a Cd decoupler. However, even in the case of the reflected assembly, the cold neutron intensities from the liquid hydrogen moderators are much less than that from the solid methane moderator; intensity ratios of the cold neutrons emitted from the hydrogen moderator to the solid methane one are about 36% for the thin hydrogen moderator and about 56% for the thick one. These results show that although the thick hydrogen moderator should be used to increase the pulsed cold neutron intensity, the pulsed cold neutron intensity from the liquid hydrogen moderator cannot be increased up to that from the solid methane moderator regardless of the use of a reflector, only by thickening the moderator.     

Effects of Hydrogen on the Methane Coupling under Non-equilibrium Plasma

1. IntroductionSince the eighties Of the 20th century, the research on the generation Of CZ hydrocarbon frommethane coupling always has been a hot subject.In recent years I non-equilibrium Plasma acting onmethane coupling has been a novel method for research, from which many sisnificant results were reportedly known in references [l~ 31. In general,the hydrogenated methane coupling has been considered to be thermodyn~ally unfavorable to thereaction, no matter what method is used, either thec…     

Interactions of 5–30 keV deuterons with a carbon surface

Measurements have been made of the temperature dependence of methane formation during the bombardment of carbon with hydrogen ions of varying energies. It has been found that the value of the temperature at which maximum methane production occurs varies with incident ion energy, in agreement with the prediction of our earlier theoretical model. Measurements have also been made of the release of previously trapped hydrogen in carbon using hydrogen and deuterium ion beams. The cross sections measured for this release as a function of energy have been used in the model for methane production and confirm that ion-induced release plays an important role in determining the methane production rate.     

Methane formation during the interaction of energetic protons and deuterons with carbon

Methane production has been investigated as a function of temperature during ion bombardment and during post-irradiation thermal release of implanted hydrogen in pyrocarbon. The reaction is shown to be directly correlated with the release of trapped hydrogen rather than an ion/surface interaction. During bombardment, methane production is not observed below target temperatures of 450 K. The methane yield reaches a maximum of 9% of the hydrogen release rate at 850 K after which it falls to <0.2% at 1200 K. No residual gas effects on hydrocarbon production have been observed even at pressures up to 10^?5 torr. Following bombardment, methane is formed during heating of the carbon at temperatures in excess of 800 K. A peak in methane production is observed at 1000 K, whilst the peak in hydrogen release occurs at 1200 K. An analytical model for the temperature dependence of methane production during bombardment is presented and this agrees well with the experimental results.     

Numerical modelling of a low power non-transferred arc plasma reactor for methane conversion

Thermal flow characteristics and the methane conversion reaction in a low power arc plasma reactor for efficient storage and transport of methane, which is the main component of shale gas, were simulated. The temperature and velocity distributions were calculated according to the type of discharge gases and arc current level by a self-developed magnetohydrodynamics (MHD) code and a commercial ANSYS-FLUENT code; the transport of chemical species was analyzed as including the chemical reactions of methane conversion. The simulated results were verified by the comparison of calculated and measured arc voltages with permissible low error as under 4%. Three C₂ hydrocarbon gases with ethane (C₂H₆), ethylene (C₂H₄), and acetylene (C₂H₂) were selected as the converted species of methane from experimental data. The mass fraction of C₂ hydrocarbons and hydrogen as the product of the conversion reaction at the reactor was also calculated. Those values show good agreement with the actual experimental results in that the major conversion reaction occurred in C₂H₂ and hydrogen, and the conversions to C₂H₆, C₂H₄, and hydrogen were minor reactions of methane pyrolysis conversion.     

Experimental study of swelling of irradiated solid methane during annealing

Solid methane is still widely in use at pulsed neutron sources due to its excellent neutronic performance (IPNS, KENS, Second Target Station at ISIS), notwithstanding poor radiation properties. One of the specific problems is radiolytic hydrogen gas pressure on the walls of a methane chamber during annealing of methane. In this paper results of an experimental study of this phenomenon under fast neutron irradiation with the help of a specially made low temperature irradiation rig at the IBR-2 pulsed reactor are presented. The peak pressure on the wall of the experimental capsule during heating of a sample irradiated at 23-35 K appears to have a maximum of 2.7 MPa at an absorbed dose 20 MGy and then falls down with higher doses. The pressure always reached its peak value at the temperature range 72-79 K. Generally, three phases of methane swelling during heating can be distinguished, each characterized by a proper rate and intensity.     

Effect of Hydrogen Atmosphere on Radiation- Induced Gas Evolution from Polyisoprene

Polyisoprene was irradiated in hydrogen atmosphere by ⁶⁰Co γ-rays. The evolved gases were methane, ethane, ethylene, propane, propylene and butane. With respect to saturated hydrocarbons, the yields increased with increasing pressure of hydrogen. On the contrary, the yields of unsaturated hydrocarbons decreased. The G-value of methane in hydrogen of 1 MPa was about four times larger than that in vacuum for irradiation of cis-polyisoprene (Cis) at 160 kGy. The gas evolution from trans-isomer (Trans) was about the same as that from Cis. The yields of gases from gloves made of natural rubber were smaller than those from Cis or Trans.     

Preliminary Study of Isotopic Methanes Analysis by Laser Raman Spectroscopy for In-Situ Measurement at Fusion Fuel Gas Processing

Application of laser Raman spectroscopy for fusion fuel gas processing was studied by measuring isotopic methanes exchanged with hydrogen isotopes, which are considered to be a major impurities in the processing. For experimental gases, isotopically equilibrated deuterium and methane were prepared in the presence of solid catalyst. Large Raman scattering peaks of v ₁, bands were observed at 2,917 cm^?1 for CH₄ and at 2,100-2,200 cm_?1 for deuterated derivatives of methane C(H,D)₄. Under a spectral resolution of 5 cm_?1, the v ¹ bands of CH₃D and CH₂D₂ were observed as an overlapped peak, the relative absolute Raman intensity ratio of each isotopic methane was obtained as CH₄: CH₃D+CH₂D₂: CHD₃: CD₄=230: 74: 144: 100. On the other hand, the Raman intensity ratio obtained from pure deuterated standard methane was CH₄: CH₃D: CH₂D₂: CHD₃: CD₄=230: 53: 33: 115: 105. It was confirmed that isotopically equilibrated hydrogen isotopes and methane mixed gas would be applicable for an alternative standard gas for fusion fuel processing gas analyzing system.     

Gaseous products generated by radiation degradation of N,N-diethylhydroxylamine aqueous solution

In this paper, gaseous products generated by radiation degradation of N,N-diethylhydroxylamine (DEHA)in aqueous solution are studied. The results show that by 10～1000 kGy irradiation of the solution in DEHA volume fraction of hydrogen did not change much with different concentrations of DEHA. The volume fraction of methane and ethane decreased, but that of ethene increased, with increasing DEHA concentration. The volume fraction of hydrogen, methane and ethane increased with the dose. The relationship of the volume fraction of ethene with the dose had something to do with the DEHA concentration.     

高温堆甲烷蒸汽重整制氢系统性能热力学分析

从热力学的角度分析高温堆甲烷蒸汽重整制氢系统的性能，为进一步研究实际的制氢系统提供框架。建立了完全反应模型和平衡反应模型，研究系统效率，产氢量随过程参数的变化关系，得到各性能指标的极限值以及过程参数的最优值。通过与实验数据的比较，采用平衡反应模型对系统进行初步分析是合适的。     

The application of nuclear process heat for hydrogasification of coal

Hydrogasification is the conversion of coal with hydrogen to methane. Because coal and water only are primarily available for gasification purposes, the hydrogen required for methane production has to be produced by the gasification process. This requires heat at a high temperature level which can be supplied by a high temperature reactor as nuclear process heat. In this paper two process variants are described for hydrogasification of lignite with nuclear process heat. The design data of a draft for commercial-scale plants are given. Also, the pilot plant of Rheinische Braunkohlenwerke AG for hydrogasification of coal in the fluidized bed is described.     

Novel Plasma Reactor with Rotary Helix Electrode Used in Coupling of CH4 at Atmospheric Pressure

At the ambient temperature and pressure a glow discharge plasma was used as a new approach for the coupling of methane with the newly-developed rotary multidentate helix electrode. In the presence of hydrogen, the effects of the input peak voltages and gas flow rates on methane conversion, C2 single pass yield and selectivity were investigated, and then the results were compared with those from the three-disc multidentate electrode. This demonstrated, on an experimental scale, that the rotary multidentate helix electrode was better than the multidentate three-disc electrode as there was little accumulation of coke, and the C2 yield per pass was 69.85% and C2 selectivity over 99.14% with 70.46% methane conversion at an input peak voltage of 2300 V and 60 ml/min gas flow rate.     

Reaction of atomic hydrogen with chemisorbed species: C2H4 on W

Atomic hydrogen produced in controlled thermonuclear reactors is capable of very rapid reaction with both the material of the first wall and with adsorbed species. We have been investigating the reactions of thermal atomic hydrogen with ethylene adsorbed on a tungsten film. When adsorbed at room temperature ethylene reacts to yield gaseous hydrogen and a carbonaceous residue which reacts with incident atomic hydrogen to yield methane along with minor amounts of ethane. This product distribution, however, depends on the chemical nature of the adsorbed species. Adsorption at 178K, a temperature at which the ethylene molecule is stable, inverts this distribution with ethane now being the major product. Analysis of the system dynamics shows that the rate of production of each product is proportional to the product of the steady state increase in the product pressure and the pumping time constant of the vacuum system. For the case of methane production following room temperature adsorption of ethylene, the reaction probability for the production of methane for the reaction C + 4H → CH₄is ~0.001 and arguments are given for a larger value.     

Investigating the performance of a Rh metal catalyst in hydrogen–deuterium exchange reactions in methane for application in low-temperature membrane separators

The development of safe, efficient, and cost effective methods to recover waste components of deuterium–tritium (D–T) plasma reactors, including hydrogen and methane, has attracted much interest in the scientific community. Typically, membrane separators are used for this process, although several problems occur when performing separations at higher temperatures. The application of noble metal catalysts may improve the reaction dynamics and allow the separation process to occur at lower temperatures. In this paper, a series of noble metal catalysts were prepared by a traditional dipping method. Based on an analysis of catalytic performance, the Rh/Al₂O₃ catalyst was determined to be the most suitable for the exchange of hydrogen and deuterium in methane. The catalyst was characterized by X-ray diffraction, X-ray photoelectron spectroscopy, and temperature programmed reduction analyses. The effects of the metal loading and experimental conditions were also investigated.     

Methane Conversion to C2 Hydrocarbons by Abnormal Glow Discharge at Atmospheric Pressure

Methane conversion to C2 hydrocarbons has been investigated with the addition of hydrogen in a plasma reactor of abnormal glow discharge at atmospheric pressure. The aim of this experiment is to minimize coke formation and improve discharge stability. The typical conditions in the experiment are 300 ml of total feed flux and 400 W of discharge power. The experimental results show that methane conversion is from 91.6% to 35.2% in mol, acetylene selectivity is from 90.2% to 57.6%, and ethylene selectivity is approximately from 7.8% to 3.6%, where the coke increases gradually along with the increase of CH4/H2 from 2 ： 8 to 9 ： 1. A stable discharge for a considerable running time can be obtained only at a lower ratio of CH4/H2 = 2：8 or 3： 7. These phenomena indicate that the coke deposition during methane conversion is obviously reduced by adding a large amount of hydrogen during an abnormal glow discharge. A qualitative interpretation is presented, namely, with abundant hydrogen, the possibility that hydrogen molecules are activated to hydrogen radicals is increased with the help of the abnormal glow discharge. These hydrogen radicals react with carbon radicals to form C2 hydrocarbon products. Therefore, the deposition of coke is restrained.     

应用于等离子体排灰气处理的甲烷水汽重整反应的热力学分析

Tokamak装置中的等离子体反应一段时间后,需对产生的排灰气进行净化处理,以回收其中的氘氚。目前拟采用甲烷水汽重整反应将化合态的氘氚转化为单质并回收。本文运用Gibbs自由能最小化方法,对应用于等离子体排灰气处理的水汽重整反应进行热力学分析,考查反应温度、原料比例、反应压力、O₂、CO₂、H₂、CO等因素对反应平衡的影响,确定了适宜的反应条件,即反应温度范围650～700 ℃,压力1×105 Pa,水碳比1.5～2.0。此外,原料气中O₂或CO₂的存在有利于减少积碳的生成量,并获得较高的氢同位素平衡转化率;H₂的存在对重整反应的热力学平衡无明显影响;CO的存在会使积碳量增加,对反应产生不利影响,在进入重整反应器前应将其去除。     

Permeation, diffusion and dissolution of hydrogen isotopes, methane and inert gases through/in a tetrafluoroethylene film

Tetrafluoroethylene (TFE) is widely used for conventional tritium handling systems such as vacuum seals, tubing and so on. We measured the permeation of the three hydrogen isotopes, methane and the inert gases through a TFE film at room temperature by means of the time-lag method in order to establish the physicochemical properties which determine the solubility and diffusivity of those gases. It was found that the diffusion constant of the inert gases changed exponentially with the heat of vaporization and the solubility was an exponential function of the Lennard-Jones force constant of the gases. On the other hand, hydrogen isotopes and methane deviated from these relations. It is concluded that chemical interactions between the solute and the solvent play an important role for the dissolution and the diffusion of these gases in TFE.     

喇曼光谱法研究辐照聚合物的气体产值

本文研究了两种典型交联型聚合物在~(60)Coγ射线辐照条件下放出的气体的激光喇曼光谱,通过波数2917cm~(-1),2954cm~(-1)和4157cm~(-1)三处特征谱峰高度与标准谱图的比较,测得辐照聚二甲基硅氧烷放出的各种气体产值:G_(CH_4)=1.05,G_(C_2H_6)=0.23,G_(H_2)=0.58,气体总产值:G_(CH_4-C_2H_6+H_2)=1.86,实验结果表明,在500Mrad剂量以下,辐照样品放出气体的总产值和各种气体的分产值不随剂量而变化,从而给予交联度与剂量成正比以直接证明。用同样方法测得辐照聚乙烯放出的气体产值(G_(CH_2)=2.7),也与辐照剂量无关。