Methane dehydroaromatization with periodic CH_4-H_2 switch:A promising process for aromatics and hydrogen

Long-term stability test of Mo/HZSM-5-N catalysts（HZSM-5-N stands for nano-sized HZSM-5） in methane dehydroaromatization（MDA）reaction has been performed with periodic CH4-H2 switch at 1033-1073 K for more than 1000 h.During this test,methane conversion ranges from 13% to 16%,and mean yield to aromatics（i.e.benzene and naphthalene） exceeds 10%.N2-physisorption,XRD,NMR and TPO measurements were performed for the used Mo/HZSM-5 catalysts and coke deposition,and the results revealed that the periodic hydrogenation can effectively suppress coke deposition by removing the inert aromatic-type coke,thus ensuring Mo/HZSM-5 partly maintained its activity even in the presence of large amount of coke deposition.The effect of zeolite particle size on the catalytic activity was also explored,and the results showed that the nano-sized zeolite with low diffusion resistance performed better.It is recognized that the size effect was enhanced by reaction time,and it became more remarkable in a long-term MDA reaction even at a low space velocity.

基于不同模型的河口区水产养殖塘水-气界面CH_4气体传输速率及扩散通量研究

模型估算法是水-气界面甲烷(CH_4)通量监测的主要方法.本研究选择6种不同的参数化模型方法估算了2015年6、8和10月两个亚热带河口养殖塘水-气界面CH_4传输速率(kx)及其扩散通量,探讨了河口养殖塘kx及CH_4扩散通量的变化特征和影响因子.结果表明:研究期间,不同模型估算下的kx及其扩散通量均值在闽江河口养殖塘变化范围分别为1.60±0.75～6.29±1.30 cm/h和9.19±2.67～30.64±6.28μmol/(m2·h),在九龙江河口养殖塘的变化范围分别为0.89±0.19～6.07±0.61 cm/h和3.18±0.48～21.03±2.13μmol/(m2·h); kx及其扩散通量在两个河口区均呈现随时间推移而升高的特征;整个养殖期间,养殖塘水-气界面平均CH_4传输速率kx呈现闽江河口略高于九龙江河口(P>0.05),但水-气界面平均CH_4扩散通量呈现闽江河口显著高于九龙江河口的特征(P<0.05);风速、水体溶解CH_4浓度和盐度是调控河口区养殖塘水-气界面CH_4扩散通量变化的重要因子;不同模型估算出的河口养殖塘水-气界面CH_4传输速率kx存在差异,表明模型估算法获得的水-气界面CH_4扩散通量存在一定的不确定性.

西太平洋雅浦海沟区海水中CH_4和DMSP的垂直变化特征

本研究首次探究了西太平洋雅浦海沟北段从表层到超深渊海水中甲烷(CH_4)及二甲基硫(DMS)的前体物质二甲基巯基丙酸内盐(DMSP)的浓度变化情况。结果表明:雅浦海沟海水甲烷浓度变化范围为1.49~3.87nmol/L。其上层海水甲烷平均浓度最高,有明显的次表层极大现象。雅浦海沟氧最小层海水的甲烷平均浓度最低;在500~1 000m中层水中甲烷浓度有一定程度的增大,1 000m以下至底层甲烷浓度继续升高。研究海区溶解态DMSP(DMSPd)和总DMSP(DMSPt)平均浓度的垂直变化随深度呈先增大后减小趋势,颗粒态DMSP(DMSPp)的平均浓度随深度呈波动式变化,在中层达到最大。雅浦海沟CH_4和DMSP浓度垂直变化受浮游生物、微生物、光照、温度、压力、大洋环流等的复杂影响。在真光层海水中,CH_4浓度与DMSPd、DMSPp和DMSPt浓度表现为负相关关系,在200m至底层海水中,CH_4浓度与DMSPd、DMSPp和DMSPt浓度表现为正相关关系,显示光照条件是造成雅浦海沟不同深度海水CH_4和DMSP浓度相关性差异的关键因素。

煤/HDPE共炭化材料CH_4吸附性能的研究

研究了手选分离的黄陵镜煤、丝炭与HDPE共混物的共炭化产物结构和性质,并对炭化产物的CH4吸附性能进行了对比分析。结果表明:煤/HDPE共炭化物产率随温度的升高而降低,镜煤/HDPE共炭化物产率远低于丝炭/HDPE;炭化温度为400℃、质量比为7:3的镜煤/HDPE共炭化产物的CH4吸附能力最强。

光干涉法实现CH_4浓度的直读式测量

讨论了如何利用现代电子技术把矿用光干涉ＣＨ４检测仪变成为直读式测量仪表的原理和设计方法，从而使老仪表焕发青春。

Discovery and Significance of High CH_4 Primary Fluid Inclusions in Reservoir Volcanic Rocks of the Songliao Basin,NE China

Comparing compositions of the fluid inclusions in volcanic rocks to the contents and isotopes of the gases in corresponding volcanic reservoirs using microthermometry, Raman microspectroscopy and mass spectrum analysis, we found that： （1） up to 82 mole% methane exists in the primary inclusions hosted in the reservoir volcanic rocks; （2） high CH4 inclusions recognized in the volcanic rocks correspond to CH4-bcaring CO2 reservoirs that are rich in helium and with a high ^3He/^4He ratio and which show reversed order of 813C in alkane; （3） in gas reservoirs of such abiotic methane （〉80%） and a mix of CH4 and CO2, the enclosed content of CH4 in the volcanic inclusions is usually below 42 mole%, and the reversed order of δ^13C in alkane is sometimes irregular in the corresponding gas pools; （4） a glassy inclusion with a homogeneous temperature over 900℃ also contains a small portion of CH4 although predominantly CO2. This affinity between gas pool and content of inclusion in the same volcanic reservoirs demonstrates that magma-originated gases, both CH4 and CO2, have contributed significantly to the corresponding gas pools and that the assumed hydrocarbon budget of the bulk earth might be much larger than conventionally supposed.

Recovering methane from quartz sand-bearing hydrate with gaseous CO2

The replacement method by CO;is regarded as a new approach to natural gas hydrate（NGH） exploitation method, by which methane production and carbon dioxide sequestration might be obtained simultaneously. In this study, CO;was used to recover CH;from hydrate reservoirs at different temperatures and pressures. During the CO;–CH;recovery process, the pressure was selected from 2.1 to 3.4 MPa, and the temperature ranged from 274.2 to 281.2 K. Calculating the fugacity differences between the gas phase and the hydrate phase for CO;and CH;at different conditions, it has found rising pressure was positive for hydrates formation process that was helpful for the improvement of CH;recovery rate. Rising temperature promoted the trend of CH;hydrate decomposition for the whole process of CO;–CH;replacement.The highest recovery rate was 46.6 % at 3.4 MPa 281.2 K for CO;–CH;replacement reaction in this work.

Modeling Methane Emissions from Paddy Rice Fields under Elevated Atmospheric Carbon Dioxide Conditions

Abstract Methane （CH4） emissions from paddy rice fields substantially contribute to the dramatic increase of this greenhouse gas in the atmosphere. Due to great concern about climate change, it is necessary to predict the effects of the dramatic increase in atmospheric carbon dioxide （CO2） on CH4 emissions from paddy rice fields. CH4MOD 1.0 is the most widely validated model for simulating CH4 emissions from paddy rice fields exposed to ambient CO2 （hereinafter referred to as aCO2）. We upgraded the model to CH4MOD 2.0 by： （a） modifying the description of the influences of soil Eh and the water regime on CH4 production; （b） adding new features to reflect the regulatory effects of atmospheric CO2 upon methanogenic substrates, soil Eh during drainages, and vascular CH4 transport; and （c） adding a new feature to simulate the influences of nitrogen （N） addition rates on methanogenic substrates under elevated CO2 （hereinafter referred to as eCO2） condition. Validation with 109 observation cases under aC02 condition showed that CHaMOD 2.0 possessed a minor systematic bias in the prediction of seasonally accumulated methane emissions （SAM）. Validation with observations in free-air CO2 enrichment （FACE） experiments in temperate and subtropical climates showed that CH4MOD 2.0 successfully simulated the effects of eCO2 upon SAM from paddy rice fields incorporated with various levels of previous crop residues and/or N fertilizer. Our results imply that CH4MOD 2.0 provides a potential approach for estimating of the effects of elevated atmospheric CO2 upon CHa emissions from regional or global paddy rice fields with various management practices in a changing climate.

Design of a Methane Monitoring System for Landfill and Duct Emissions

Methane is released from waste disposal areas as a result from anaerobic decay of food. Methane causes more greenhouse effects than carbon dioxide so a methane monitoring system is required to warn its release from gas emitting environments. The low explosive limit of methane is 5% in ambient air, so gas leakage is dangerous and can produce explosions. An entire head monitoring system was built around a MQ-4 methane gas sensor as it is cheap and reliable. The design proves to be flexible enough as it can measure CH4 emissions in ducts, CH4 in landfills at different depths and even in cattle barns. The measuring system head consists of a suction pump, solenoids, and a methane sensor. Measurements are taken 13 seconds after methane gas sucking. A timing of 100 seconds is required for purging the chamber before the second solenoid is turned-on. Devices temperature during operation was sampled with a thermal Flir-One camera and solenoid coil temperature was of 24.9˚C after a continuous operation of 30 seconds. As hoses for emission sampling become larger time for sampling increases as well as energy consumption.

Methane Adsorption on Montmorillonite, Kaolinite and Illite at High Pressures

Shale gas, which is derived from organic matters in shale and stored in shale deposits, is an important unconventional gas resource and attracts attention due to its significant requirement in the hydrocarbon production. Methane (CH4) is the dominant component of shale gas, and adsorbed gas is an important reservoir form. Many studies have investigated the adsorption capacities and adsorption mechanisms of CH4 in shale. Organic matters and clay minerals have been proposed to be the two major components for CH4 adsorption. Adsorption of CH4 in organic matters, such as the adsorption capacity and effects of characteristics of the organic matters, has been well investigated. However, studies on CH4 adsorption on clay minerals have mainly focused on evaluating the adsorption capacity, and very little information about the adsorption mechanism has been provided. For example, the adsorption sites and factors influencing CH4 adsorption on clay minerals remain unclear. Three main reasons account for this: (1) the co-existence of organic matters in samples affects the evaluation of CH4 adsorption on clay minerals; (2) the pressures used during adsorption are not representative of actual reservoir pressures; and (3) the clay minerals selected have low swelling capacity and a smaller interlayer distances than a CH4 size, resulting in the misunderstanding of the CH4 adsorption sites.

分布式激光甲烷检测系统及温度补偿技术研究

瓦斯浓度检测精度不高、传感器后期检修工作量大,是当前煤矿瓦斯灾害防治中存在的重要问题。针对这一问题,设计了一种光纤传输的分布式激光甲烷检测系统,并研究了其配套的温度补偿方案。阐述了采用可调谐激光光谱吸收技术和光复用技术进行多通道系统设计的方法,进而分析环境温度变化与甲烷吸收光谱的影响关系,在此基础上提出了一种基于实验测试数据的多变量自适应温度补偿算法,实现了瓦斯浓度在大空间复杂温度场条件下的准确检测。测试结果表明:该系统能够实现64个测点在10 km范围内的准确检测;进行温度补偿后,在0~40.0℃温度变化范围内,甲烷体积分数测量范围为0~100.00%,测量误差小于±2.00%。该系统适用于煤矿通风巷道、采煤工作面等危险场所,具有测量精度高、信息覆盖面广、气室无源、本质安全、成本低等特点,可为煤矿瓦斯突出预警和瓦斯抽采提供准确的基础数据。

彩虹-4无人机航磁三分量测量系统研发及应用研究

随着无人机技术的快速发展,无人机在航空物探领域中日益发挥着积极的作用;通过科技攻关,我国首次基于国产彩虹-4无人机平台,开展了无人机平台改装与系统集成、无人机航磁三分量磁补偿等核心和关键技术研究,成功地研发出首套具有自主知识产权的彩虹-4无人机航磁三分量测量系统,主要包括彩虹-4无人机平台、三分量磁力仪、光泵磁力仪、高精度惯导系统、高度计、数据采集和收录系统等组成;并在国内首次开展了无人机航磁三分量面积性应用飞行试验,全面验证了系统的稳定性、可靠性及适应性等,试验结果表明航磁三分量精度达到25 nT,为实现我国在青藏高原和远海开展大中比例尺、高精度航磁三分量测量工作提供先进技术支撑,具有很好的应用前景.

Simulation of a NGCC Power Generation Plant for the Production of Electricity from CO₂Emissions Part I: The Methanation Reactor

The final goal of this applied research is to simulate a Natural Gas Combined Cycle (NGCC) power plant with a CO2 capture unit. The originality of this investigation is the integration of a methanation process to produce the natural gas of the power plant from the captured CO2. The objective of this first part of the investigation is to simulate a methanation reactor for the production of methane using 1 kg/hr. of captured carbon dioxide containing 95% mol. CO2 and 5% mol. H2O. To reach this goal, Aspen Plus software and the Redlich-Kwong-Soave equation of state with modified Huron-Vidal mixing rules are utilized. Three parameters are considered in order to maximize the production of CH4 production: 1) temperature, varying from 250°C to 300°C, 2) pressure varying between 10 atm to 40 atm and 3) [H2/CO2] ratio which varies between 2 to 6. The maximum production of methane of 0.875 kmol/hr. was obtained for the following operating conditions: [H2/CO2] ratio of 3.5, at relatively low temperature (250°C - 270°C) and high pressures 30 and 40 atm.

洛伦兹线型近似引起的甲烷检测误差研究

2ν_(3)波段R3分支(6 046.95 cm^(-1))是近红外甲烷检测领域最常用波段。R3分支三条谱线相距很近,通常用一条谱线的洛伦兹线型去描述其谱形,校正温度、压强引起的二次谐波峰值误差,然而洛伦兹线型本身引起的误差并没有得到足够的重视。对TDLAS系统建模分析,以低频锯齿波叠加高频正弦波调制激光,经待检测气体吸收后,再利用数字锁相放大及低通滤波实现解调,最终通过旋转坐标系得到一次谐波归一化的二次谐波信号。通过分别比较单条谱线洛伦兹线型与三条谱线Voigt线型对二次谐波的影响,分析温度、压强变化条件下,由单条谱线洛伦兹线型近似带来的二次谐波误差。结果表明:(1)压强、温度变化时,洛伦兹线型二次谐波峰值误差较平均极小值误差更小;(2)洛伦兹线型二次谐波峰值的误差随着压强降低而显著增加,温度为298 K、压强降低至0.2 atm时,由洛伦兹线型近似带来甲烷气体二次谐波峰值的误差达65.5%;(3)以峰谷率、谐波宽度等参数衡量二次谐波谱形,在温度为298 K、压强小于0.8 atm条件下,峰谷率误差大于4.5%,压强为1 atm、温度大于380 K条件下,峰谷率误差大于4.8%,由于二次谐波谱形误差对于峰谷率参数较为敏感,因此对于6 046.95 cm^(-1)处的甲烷气体,洛伦兹线型很难适用于免校准算法;(4)洛伦兹线型近似误差随调制系数增加而减小,当温度为298 K、压强为1 atm,调制电流大于2.2 mA(对应调制系数1.33)时,二次谐波峰值误差、峰谷率误差和宽度误差都小于3.5%。所提出的洛伦兹线型误差分析方法,对研究温度、压强变化环境下线型近似引起的TDLAS的甲烷检测误差有一定的参考意义,也可推广至其他气体多谱线波段的TDLAS检测。

Water regime-nitrogen fertilizer incorporation interaction：Field study on methane and nitrous oxide emissions from a rice agroecosystem in Harbin, China

Water regime and nitrogen（N） fertilizer are two important factors impacting greenhouse gases（GHG） emission from paddy field, whereas their effects have not been well studied in cold region. In this study, we conducted a two-year field experiment to study the impacts of water regime and N fertilizer on rice yields and GHG emissions in Harbin, China, a cold region located in high latitudes. Our results showed that intermittent irrigation significantly decreased methane（CH4） emission compared with continuous flooding, however,the decrement was far lower than the global average level. The N2O emissions were very small when flooded but peaked at the beginning of the disappearance of floodwater. The N fertilizer treatments increased CH4 emissions at low level（75 kg N/ha）. But both CH4 and N2O emissions were uninfluenced at the levels of 150 kg N/ha and 225 kg N/ha. Rice yields increased under intermittent irrigation and were highest at the level of 150 kg N/ha. From our results, we recommended that the intermittent irrigation and 150 kg N/ha as the ideal water regime-nitrogen fertilizer incorporation for this area to achieve low GHG emissions without impacting rice yields.

Anaerobic digestion of cyanobacteria and chlorella to produce methane for biofuel

The methane potentials of cyanobacteria and chlorella have been investigated in eight different lab scale reactors at 25℃for three-day Hydraulic Retention Time(HRT).Autoclavation pre-treatment was applied to the cyanobacteria to aid digestion,while the Chlorella was obtained and digested in powdery form.The organic loading rates were 1g VS,2 g VS,3 g VS,4 g VS,5 g VS,6 g VS,7 g VS,8 g VS and 9 g VS.Methane production rates increased with increasing loading rates and started declining at loading rate higher than 7 g VS,while the HRT was kept constant.The highest methane production rates for cyanobacteria and chlorella were(78±25)mL/(L·d)and(100±25)mL/(L·d),respectively,at loading rate of 7 g VS.Digester instability occurred at loading rates of 8 g VS and 9 g VS with higher accumulation of methane concentrations.Lipid compositions of both feeds were close and the methane production potentials of both biomasses were also close and followed the same trend.

垃圾中甲烷产率计算及全国垃圾甲烷气资源估算

本文比较分析了几种常用的有关垃圾场甲烷气产率计算方法，并详细计算了甲烷的产率及累计产量，在此基础上用一个比较实际的垃圾填埋场计算垃圾填埋过程中甲烷气的产率情况及累计产量，为垃圾填埋场的沼气发电提供了可靠的资料。并用此方法计算了全国各省份垃圾的甲烷排放量，并大致计算了全国的垃圾中甲烷资源的潜力。

钙钛矿型复合氧化物在甲烷部分氧化反应中催化性能的研究

Ba\-\{0.5\}Sr\-\{0.5\}Co\-\{0.8\}Fe\-\{0.2\}O\-\{3-\%δ\%\} and Ba\-\{0.5\}Sr\-\{0.5\}Co\-\{0.8\}Ti\-\{0.2\}O\-\{3-\%δ\%\} oxides were synthesized by a combined EDTA\|citrate complexing method. The catalytic behavior of these two oxides with the perovskite structure was studied during the reaction of methane oxidation. The pre\|treatment with methane has different effect on the catalytic activities of both the oxides. The methane pre\|treatment has not resulted in the change of the catalytic activity of BSCFO owing to its excellent reversibility of the perovskite structure resulting from the excellent synergistic interaction between Co and Fe in the oxide. However, the substitution with Ti on Fe\|site in the lattice makes the methane pre\|treatment have an obvious influence on the activity of the formed BSCTO oxide.

在 M/MgO 催化剂上甲烷部分氧化制合成气

比较了以ＭｇＯ为载体的四种负载型催化剂在甲烷部分氧化反应中的催化活性，表明Ｒｈ具有最高活性。用Ｄ２（氘）－ＣＨ４同位素交换反应揭示，金属组份解离甲烷的能力与其催化活性紧密相关，在甲烷部分氧化反应中具有高活性的催化剂解离吸附甲烷分子的能力强，且以形成ＣＤ４为主的氘代甲烷产物分布，其次序为：Ｒｈ＞Ｒｕ＞Ｐｔ＞Ｐｄ。揭示了ＣＯ选择性随反应气流量增大、反应接触时间的缩短而提高，表示ＣＯ可能是甲烷部分氧化反应中的初始产物。还探讨了双金属组份催化剂的催化行为。

基于中红外DFG光源的甲烷气体光谱检测方法研究

基于中红外光源的气体光谱检测是新的痕量气体监测与分析方法,在大气监测领域具有重要的应用。构建了一套基于中红外DFG光源的甲烷气体光谱检测系统。该系统以1 550nm和1 060nm波段可调谐半导体激光器作为基频光源,采用PPLN晶体作为差频非线性变频器件,实现了3.3μm处的窄线宽可调谐中红外光源输出。实验结果表明,当PPLN晶体工作温度为99.5℃时,闲频光的输出功率为112μW,差频转换效率达到1.246mW/W2。晶体的温度接受带宽为4.3℃,泵浦光波长接受带宽为5.3nm。在此基础上,分别利用直接吸收法和谐波检测法获得了3 028.751cm-1处的甲烷气体吸收光谱和二次谐波检测信号。