煤体变形对CH4吸附/解吸特性的影响

煤体变形存在于煤层气开采的整个过程中,其对气体的吸附/解吸有着重要的影响,它们之间的关系更是影响到煤层气的产量。采用分子模拟软件Materials Studio(MS)对赵庄3#煤模型进行了不同应变下CH4的等温吸附分子模拟,根据模拟结果给出了煤体变形与CH4吸附/解吸量之间的关系式,并对此关系式进行了误差分析,结果表明此关系式能够满足工程要求。     

煤对超临界甲烷的吸附与解吸特性研究

研究了晋城和潞安煤对超临界 CH4的吸附与解吸特性 ,利用 SPSS软件对 Lang-muir,BET,D- R和 D- A四个模型对煤 CH4吸附和解吸实验数据进行拟合 ,并分别检验了实验数据的拟合程度 .结果表明 :煤吸附和解吸过程并不可逆 ,煤解吸 CH4时的吸附量要比煤吸附 CH4时的吸附量高 ;这些模型对煤吸附和解吸过程中的吸附 CH4实验数据都具有较好的拟合 ,D- A提供了最好的拟合 ,Langmuir的拟合度最差 ;各模型对解吸数据的拟合度要比吸附数据的拟合度好 .     

注入二氧化碳驱替煤层甲烷的试验研究

根据煤储层吸附-解吸机理,采用注入CO2驱替煤样CH4实验研究.结果表明:CO2的吸附能力高于CH4.CO2驱替与纯CH4的解吸过程比较表明,CH4在单位压降下的解吸率,明显高于纯CH4解吸时单位压降下的解吸率,CH4的解吸率比原来提高77.7%.     

煤的原子分子结构及吸附甲烷机理研究进展

总结了煤的原子径向分布与微晶结构、稠环芳烃的电子光谱规律与煤的颜色间的关系、煤与CH4分子的相互作用、无烟煤及其炭化样吸附／解吸甲烷的热力学和动力学过程等内容的研究与发展，结果表明：(1)低阶煤的微晶参数d002，Ic和Ia随含碳量呈阶段性变化，其微晶结构特征与纤维素的结构有关，并可用煤化度p定量描述煤化过程中煤的微晶结构变化。(2)煤中存在13个苯环以上稠环芳香结构单元，(3)甲烷分子与煤表面的相互作用各向异性，最大作用势(吸附势)为2．65kJ／mol，旋转势垒为1．34kJ／mol，预计吸附振动光谱的跃迁基频为53cm^-1。(4)煤对甲烷的饱和吸附量几乎不随温度变化，炭化样与活性炭的饱和吸附量则随温度的降低而线性增大；从煤制备的炭化样，以及活性炭的吸附热都接近甲烷液化热，而煤的吸附热则高出近一倍。(5)煤层(粒)吸附解吸甲烷的动力学过程可用通用的一级组合模型和实用的吸附(解吸)扩散控制模型来描述，其三常数动力学公式中的初始吸附(解吸)率Q0／Qmax可作为煤与瓦斯突出预测指标。(6)甲烷在无烟煤中的扩散系统为～10^-10cm^2／s，扩散活化能为14．3kJ／mol；甲烷在煤中的扩散实为通过微孔的流动。     

基于DA模型的煤表面甲烷吸附线预测

采用高低温甲烷吸附解吸测试系统,在243.15, 263.15, 283.15, 303.15和323.15 K下用不同变质程度的煤(气肥煤、焦煤、贫煤和无烟煤等)对甲烷进行等温吸附,基于微孔填充Dubinbin?Astakhov(DA)模型对其它环境温度下煤的CH4吸附等温线进行预测. 结果表明,不同变质程度的煤对甲烷的吸附量均随温度降低而增大,且饱和吸附量和特征吸附能与温度具有良好的线性关系. 模型预测的等温吸附曲线与实验结果吻合较好,相对误差不超过5%.     

新场碳同位素特征

新场地区是四川盆地的主要产气区,文中研究了新场地区不同层位及由西向东的天然气碳同位素组成特征,大多数气样的δ^13C具有正碳同位素系列（δ^13C1〈δ^13C2〈δ^13C3〈δ^13C4）,显示天然气为典型的有机成因气,且是与煤型气相关的天然气,C1、C2、C3同位素分布直方图的主峰变化范围小,显示出天然气母质类型较为单一。随着干燥系数的增大,天然气的成熟度也随之增大。     

煤化度对煤层气成藏特性影响规律的研究

综述了煤层气的成因类型和成气过程的研究现状,说明生物成因和热成因是煤层气的2种主要成因类型,且煤层气生成过程以热成因为主,生物成因为辅。通过分析不同煤化度煤层气的生成过程,说明在整个煤化作用过程中煤层气的生成大致经历了4个阶段,即由植物遗体转化为泥炭阶段、褐煤转型阶段、长焰煤～瘦煤转化阶段以及贫煤～无烟煤阶段。从煤化度角度阐述了不同煤化度煤层气的贮藏特性,即不同煤化度煤层气存在较大差异,特别是不同煤层气吸附、解吸特征的差异影响了其吸附成藏、解吸、渗流及产出的整个过程;煤吸附CH4的能力随着煤化度的增加呈现先急剧增加后缓慢减小的趋势。最后分析了不同煤化度煤层气存在成藏差异的原因,说明煤化学结构、煤物理结构以及成煤过程中地质条件的差异是导致不同煤化度煤层气富集成藏差异性的主要原因。     

煤吸附与解吸甲烷的动力学规律

用容量法测定了甲烷在煤中的吸附（解吸）容量及其随时间的变化关系，提出了吸附（解吸）－扩散控制模型即．结果表明这一模型可以解释不同煤种在变温、变压时吸附与解吸甲烷的动力学过程。     

三段逐级变压吸附浓缩煤层气的工艺设计及计算

文章提出了采用分子筛吸附剂,逐级变压吸附浓缩煤层气工艺的方法,通过三段吸附-解吸将甲烷含量10%的低浓度煤层气浓缩到甲烷含量80%。一、二级采用加压吸附、常压解吸的变压吸附工艺;三级真空解吸变压吸附运用四塔操作。对该工艺中每段所需分子筛量和分子筛的吸附容积进行了计算。     

煤分子结构对煤层气吸附与扩散行为的影响

对煤的芳香单元延展度、芳香单元堆砌层数以及包括不同缺陷和含氧官能团类型的表面结构对煤层气吸附与扩散的影响进行了研究。采用Monte Carlo模拟方法及分子动力学模拟方法分别得到了煤层气的吸附量与扩散系数,模拟温度为303 K,压力为10 MPa。研究结果表明,单位质量的煤对甲烷的吸附量随着芳香单元堆砌层数的增加而降低,缺陷和含氧官能团的存在不利于甲烷的吸附。甲烷的扩散随着芳香单元延展度的增加呈现出一个N形的复杂变化过程,单缺陷和羰基的存在有利于煤层气的扩散,煤结构中大的裂隙更有利于煤层气的扩散。最后,基于煤层气的微观影响因素和宏观运移行为提出了煤颗粒径向不均质的煤层气扩散微观模型。     

甲烷单加氧酶催化反应机理和化学模拟研究进展

介绍了甲烷单加氧酶(MMO)在自然界中存在的两种形式及其组成和作用。甲烷单加氧酶是一个三组分复合酶体系，三组分分别是羟基化酶(MMOH)、调节蛋白B(MMOB)和还原酶(MMOR)。羟基化酶是其催化活性中心，它的催化机理的研究主要包括烷烃的活化和分子氧的活化这两个方面。另外还介绍甲烷单加氧酶化学模拟初步的发展状况。     

The catalytic low temperature oxydehydrogenation of methane. Temperature dependence,carbon balance and effects of catalyst composition

In an earlier publication [1] it has been claimed that oxidative coupling of methane to higher hydrocarbons had been obtained with close to 100% selectivity at 600 ° C and atmospheric pressure in the presence of steam over a CaNiK oxide catalyst. These results have been confirmed in longer runs. Artifacts, such as carbonate formation on the catalyst, have been excluded. The reaction is slightly exothermic. An Arrhenius plot shows that methane oxidation to CO₂ predominates at temperatures above 600 ° C and oxidative methane coupling at lower temperatures. The importance of exact catalyst composition is demonstrated.     

Factors and processes controlling methane emissions from rice fields

Understanding the major controlling factors of methane emissions from ricefields is critical for estimates of source strengths. This paper reports results on the relationship of different plant characteristics and methane fluxes in ricefields. Methane fluxes in ricefields show distinct diel and seasonal variations. Diel variations are mainly controlled by soil solution temperature and the partial pressure of methane. One or two distinct seasonal maxima are observed in irrigated ricefields. The first is governed by methane production from soil and added organic matter and a second at heading is plant derived. During ripening and maturity, root exudation, root porosity and root oxidation power may control methane emission rates. Rice plants play an important role in methane flux. The aerenchyma conduct methane from the bulk soil into the atmosphere. The amount of carbon utilized in methane formation varied among cultivars. A strong positive effect of rice root exudates on methane production imply that cultivar selections for lower methane emissions should not only be based on the gas transport capabilities but also on the quality and quantity of root exudates. Soils show a wide range of methane production potential but no simple correlation between any stable soil property and methane production is evident. Various cultural practices affect methane emissions. Defined aeration periods reduce methane emissions. Soil entrapped methane is released to the atmosphere as a result of soil disturbances. Mineral fertilizers influence methane production and sulfate containing fertilizer decrease methane production. The methane release per m² from different rice ecosystems follow the order: deepwater rice>irrigated rice>rainfed rice. Abatement strategies may only be accepted if the methane source strength of ricefields is reliably discriminated and if mitigation technologies are in accordance with increased rice production and productivity. This revised version was published online in August 2006 with corrections to the Cover Date.     

低浓度煤层气分离提纯的研究进展

综述了应用于低浓度煤层气分离的主要方法,包括低温精馏法、吸附分离法、膜分离法和水合物法,探讨了各种方法在不同工艺条件下的分离效果,分析了它们的优缺点。文中总结了每种方法需要解决与突破的关键性问题：低温精馏法获得的甲烷浓度高,但在处理含氧煤层气时首先要脱氧;吸附分离的关键技术在于吸附剂的选择,吸附剂决定了该方法的经济效益与难易程度;对于膜法分离,影响煤层气分离效果的主要因素在于膜材料的选择及制膜工艺;对于水合物法,寻找制备具有较高分离效率的添加剂是关键。最后指出,多种方法结合、多级分离的分离方法是未来研究发展方向。     

Acid-base properties and the directions of oxidative transformation of methane over nickel-based catalysts

The reactions of dry (CO₂) reforming and partial oxidation of methane have been investigated in a membrane reactor. The membrane is composed of a dense thin silica (SiO₂) film supported on porous Vycor tubes and was synthesized by chemical vapor deposition. The hydrogen permeance of the membrane was 0.2–0.3 cm³/(cm² min atm) at 600°C combined with a H₂/N₂ selectivity of 200–300. Significant increases in methane conversion were attained in both reactions at 500–750°C, albeit at very low space velocities. The membrane permeance declined by 50% after exposure to feeds containing H₂O, but otherwise exhibited excellent stability under reaction conditions.     

影响煤层甲烷储气量的主要因素分析

针对煤层的生气量、储气能力、煤层孔隙、割理、裂隙发育、煤层渗透率及其存在环境等影响因素进行了分析，并对煤层甲烷含量与各影响因素间的关系进行了综述。     

Steam and Dry Reforming Processes Coupled with Partial Oxidation of Methane for CO2 Emission Reduction

CO₂ is thought to contribute to global climate change. A novel integrated process of steam methane reforming (SMR) and dry methane reforming (DMR) coupled to partial oxidation of methane (POX) has been developed that utilizes the compensating heat effects of DMR and POX and recycles a large amount of CO₂ to the DMR+POX section. Both SMR and the integrated process were simulated using Aspen Plus and were optimized to operate under their respective optimum operating conditions. Modified mitigation cost (MMC) was implemented as the evaluation method. The results demonstrate that the combined process is more efficient than the SMR process due to its reutilization of CO₂ and lower requirement of raw materials.     

Global warming and the mining of oceanic methane hydrate

The impacts of global warming on the environment, economy and society are presently receiving much attention by the international community. However, the extent to which anthropogenic factors are the main cause of global warming is still being debated. There are obviously large stakes associated with the validity of any theory since that will indicate what actions need to be taken to protect the human races only home—Earth. Most studies of global warming have investigated the rates and quantities of carbon dioxide emitted into the atmosphere since the beginning of the industrial revolution. In this paper, we focus on the earths carbon budget and the associated energy transfer between various components of the climate system. This research invokes some new concepts: (i) certain biochemical processes which strongly interact with geophysical processes in climate system; (ii) a hypothesis that internal processes in the oceans rather than in the atmosphere are at the center of global warming; (iii) chemical energy stored in biochemical processes can significantly affect ocean dynamics and therefore the climate system. Based on those concepts, we propose a new hypothesis for global warming. We also propose a revolutionary strategy to deal with global climate change and provide domestic energy security at the same time. Recent ocean exploration indicates that huge deposits of oceanic methane hydrate deposits exist on the seafloor on continental margins. Methane hydrate transforms into water and methane gas when it dissociates. So, this potentially could provide the United States with energy security if the technology for mining in the 200-mile EEZ is developed and is economically viable. Furthermore, methane hydrate is a relatively environmentally benign, clean fuel. Such technology would help industry reduce carbon dioxide emissions to the atmosphere, and thus reduce global warming by harnessing the energy from the deep sea.     

Carbon monoxide induced desorption of alkanes and alkenes up to C8 after chemisorption of methane on platinum

CH₄ homologation can proceed under reductive conditions by successive exposures of various supported metals to CH₄ and H₂. When a Pt/SiO₂ catalyst is submitted to a CO dose after an exposure to CH₄ at a moderate temperature, several hydrocarbons are released with a large proportion of olefins. It may therefore be concluded that C-C bonding processes take place during the mere exposure of platinum to CH₄ at moderate temperatures.     

有机废弃物厌氧消化产沼气技术研究进展

综述了国内外关于沼气发酵菌群、工艺控制、过程控制和反应器方面的研究进展，并对其应用和研究前景作了展望，同时指出了目前该技术研究存在的主要问题，并对今后的研究和推广提出了一些建议。