Nanocapsule for Safe and Effective Methane Storage

A nanocapsule for safe and effective methane storage is investigated by the method of molecular dynamics. The mass content of methane in the nanocapsule reaches the value of 14.5 mass%. The nanocapsule consists of two parts: a locking chamber and a storage area. The locking chamber is the nanotube (10.10), open at one end, with a K@C₆₀ ¹⁺ endohedral complex inside it. The storage area is a nanotube (20.20). The locking chamber and the storage area are joined with each other and form T-junction. The locking chamber is opened at the methane filling and the discharge stages, and it is closed at the storage stage. Thanks to the locking chamber, methane molecules are stored in the nanocapsules under normal external conditions. Opening and closing of the locking chamber are carried out by the K@C₆₀ ¹⁺ endohedral complex displacement, which is done by the electric field action. The specific structure of the nanocapsule allows two aims to be reached: a high methane mass content and significant level of safety.     

Methane hydrate formation and dissociation behaviors in montmorillonite

The methane hydrate formation and the methane hydrate dissociation behaviors in montmorillonite are experimentally studied. Through the analyses of the microstructure characteristic, the study obtains the porous characteristic of montmorillonite. It is indicated that methane hydrate in montmorillonite forms the structure I(sI) crystal.Meanwhile, molecular dynamics simulation is carried out to study the processes of the methane hydrate formation and the methane hydrate dissociation in montmorillonite. The microstructure and microscopic properties are analyzed. The methane hydrate formation and methane hydrate dissociation mechanisms in the montmorillonite nanopore and on the montmorillonite surface are expounded. Combining the experimental and simulating analyses,the results indicate the methane hydrate formation and methane hydrate dissociation processes have little influence upon the crystal structure of porous media from either micro-or macro-analysis. It is beneficial to the fundamental researches on the exploitation and security control technologies of natural gas hydrate in deep-sea sediments.     

红光响应眼镜蛇神经毒素PEG-PLGA纳米囊的制备与表征

以聚乙二醇-聚乳酸-聚乙醇酸嵌段共聚物(PEG-PLGA)为囊材,添加脱镁叶绿酸作为光敏剂,采用复乳法制备了光响应的眼镜蛇神经毒素纳米囊。以纳米囊的包封率、载药量和粒径为指标,采用单因素法对纳米囊的制备条件进行优化;以差示量热扫描分析其热流变性能,并以累积释药量研究其光控释行为。优化的PEGPLGA、眼镜蛇神经毒素及光敏剂脱镁叶绿酸质量配比为40∶12.5∶1,获得的纳米囊包封率为72.3%±3.6%,载药量为15.1%±1.3%,平均粒径为(862±23)nm,电位为(-46.5±3.8)m V,呈紧密球形,光敏剂分布在囊壳;在650 nm半导体激光照射30 min,体外释放明显加快。该纳米囊在不光照时具有增强药物稳定和缓释作用,而红光可促进药物释放,因而可实现光控靶向。     

Methane Oxidation in Pig and Cattle Slurry Storages, and Effects of Surface Crust Moisture and Methane Availability

Storages with liquid manure (slurry) may develop a surface crust of particulate organic matter, or an artificial crust can be established. Slurry storages are net sources of atmospheric methane (CH₄), but a potential for bacterial oxidation of CH₄ in surface crusts was recently suggested in a study of experimental storages. The present study was conducted to investigate methanotrophic activity under practical storage conditions. Surface crusts from slurry storages at two pig farms and four dairy farms were sampled in late autumn. Mixed samples (0–4 cm depth) were used to determine changes in CH₄, O₂ and CO₂ during incubation, while intact subsamples were used to characterize CH₄ oxidation as a function of CH₄ availability and moisture content. Methane oxidation was observed in all materials except for an expanded clay product (Leca) sampled from a pig slurry storage. Despite significant variation between replicate subsamples, there was a significant increase in methanotrophic activity when CH₄ concentrations increased from 500 to 50,000 ppmv. Maximum fluxes ranged from −1 to −4.5 g CH₄ m⁻² d⁻¹. Surface crust samples were partly dried and then re-wetted in four steps to the original moisture content, each time followed by determination of CH₄ fluxes. Only one surface crust material showed a relationship between CH₄ fluxes and moisture content that would implicate gas diffusivity in the regulation of CH₄ oxidation. The occurrence of inducible CH₄ oxidation activity in slurry storage surface crusts indicates that there is a potential for stimulating the process by manipulation of gas phase composition above the stored slurry.     

浅谈盐酸贮存设备的结构设计

介绍了盐酸贮存设备的发展进程.结合实例,对目前被广泛用于盐酸贮存的机械缠绕玻璃钢大型贮槽的设计进行了描述.     

Activities of MFI-Supported Rhenium Catalysts for the Aromatization of Methane: Effect of Cationic Form of the Inorganic Carrier

MFI type inorganic carrier was used in two different cationic forms, hydrogen and calcium respectively. MFI-supported molybdenum and rhenium catalysts were prepared. The activities of the catalysts were compared for the aromatization reaction of methane. Higher activity values were attained with the catalysts supported on HZSM-5. Aromatics were also observed with the catalysts supported on CaZSM-5, despite their deficiency in acid sites. Highly dispersed rhenium is expected to be formed with the use of the inorganic carrier in calcium form. On the other hand, lower reaction rates were observed with rhenium supported on CaZSM-5, in spite of the improved dispersion of the active rhenium species on this catalyst. This was interpreted in terms of the critical role of the acid sites in the conversion of methane to aromatics, compared to the improved dispersion of the active metal.     

Oxidant Activation Over Structural Defects of Oxide Catalysts in Oxidative Methane Coupling

Different aspects concerning the process of direct methane conversion to oxygen-containing products developed during more than half a century have been considered in previous reviews [1-3]. In particular, Gesser et al. [13 paid most attention to the homogeneous stages in methane conversion, while Foster [2] and Pitchai and Klier [3] examined the effect of different catalysts on methanol and formaldehyde formation. At present the main product of the homogeneous methane oxidation process with oxygen is shown to be methanol formed according to a chain-branching mechanism. In the presence of homogeneous initiators [4] (benzene, 2,2,4- trimethylpentane, etc.) or heterogeneous catalysts [2,3,5,6], formaldehyde is formed together with CH30H. However, the yield of the desirable products is low and does not exceed 8-10%. Charged atomic oxygen forms are considered to take part in the process of catalytic methane oxidation.     

基于凝胶干水的水合物储甲烷实验研究

利用搅拌器通过高速剪切的方法制备了疏水性气相二氧化硅(HB-630):结冷胶:水的质量比为1:2:17的凝胶干水,用显微镜观察了其微观形貌,并用高压水合物反应装置对其进行了储甲烷实验研究。显微观察发现,凝胶干水粒径范围为10～150(?)m。储甲烷实验表明,在压力为7.98 MPa、温度为0.8℃左右甲烷能在6 min内与凝胶干水作用快速生成水合物,并且2 h内储甲烷量达到100(V/V),大大提高了水合物储甲烷速率和短时间内的储气量。通过5次循环储甲烷实验发现,凝胶干水储甲烷量随着循环次数的增加而降低。     

次氯酸钙对水合物中甲烷储气量的影响

1 INTRODUCTION At present,natural gas accounts for 3% of the total energy consumption in China.It will go up to 5% in 2005 and 8% in 2010. Natural gas storage is a subject of great interest to many industries and particularly to transportation.Compressed natural gas,liquefied natural gas and adsorbed natural gas are techniques widely used.The possibility of developing a convenient storage system based on hydrate has been explored for about ten years around the world[1-5].Gudmundsson[1] has focused on the storage and transportation of gas as hydrate at atmospheric pressure since 1990.Khokhar[2] used 1,3-dimethylcyclohexane and polyvinyl-pyrrolidone as additives to lower hydrate formation pressure. Saito[3] surveyed the effects of tetrahydrofuran and acetone.Rogers[3] used sodium dodecyl sulfate as accelerator to natural gas hydrate formation. In this work,the effects of calcium hypochlorite on hydrate formation are investigated.The data show that it can lower the degree of supercooling and enhance the relative cage occupancy.     

煤层气水合物技术在储运中的应用

对煤层气和水在一定条件下生成结晶状物质（NGH）从而使得煤层气以固态方式储运进行了研究。结果表明：NGH制备和储存条件温和，分解技术难度不大。与传统储运技术相比，应用NGH技术储运煤层气密度高、费用低，而且安全可靠，在煤层气储运和矿井瓦斯处理等方面都具有很高的应用价值。     

低温相变蓄热材料研究进展

蓄热技术是解决能源危机的重要手段之一,相变温度在60～80℃范围内的蓄热材料被广泛应用于太阳能储存、工业废热回收、电子器件热管理以及供暖和空调系统等领域。本文介绍了常用的可作为相变材料(PCMs)的有机物和无机物,探讨了复合相变材料的制备方法,分析了该类型相变蓄热材料的应用现状及发展前景。     

Modified Lanthanum Catalysts for Oxidative Chlorination of Methane

Mixtures of LaOCl and LaCl₃ are promising catalysts for oxidative chlorination of methane to methyl chloride. The influence of metal dopants such as Co, Ni and Ce, which form stable chlorides under anticipated reaction conditions, on physicochemical and catalytic properties was explored. The presence of markedly redox-active dopants such as cobalt and cerium lead to a higher rate of methane conversion. However, the formed methyl chloride is strongly adsorbed and directly oxidized to CO leading to low methyl chloride selectivity. Doping with nickel weakens, in contrast, the interaction with methyl chloride leading to high methyl chloride selectivity. Angeliki A. Lemonidou is on leave from the Department of Chemical Engineering, Aristotle University Thessaloniki.     

Numerical Analysis of the Catalytic Combustion of Premixed Methane/Air Mixtures in Microtubes

The combustion characteristics and extinction limits for the catalytic combustion of a methane/air mixture in a microtube are investigated computationally using the commercial CFD code FLUENT coupled to an external subroutine DETCHEM. The effects of the microtube dimensions, conductivities of wall materials, external heat losses and flow velocity on the combustion stability, are also studied. The numerical model is set as either adiabatic or non‐adiabatic with a fixed exterior heat transfer coefficient. Numerical results indicate that thermal conductivity and wall thickness are vital to preheat the methane/air mixture through the conducting wall. Two types of extinction occur, i.e., thermal quenching and blow out. These extinction limits are characterized by wall surface temperature in the microtube and the ratio of Pt(s)/O(s).     

用于甲烷选择性氧化反应制甲醇的膜催化技术

研究了将甲烷选择性地一次氧化制取甲醇的膜催化技术。采用ZrO2－Y2O3陶瓷膜，在较温和的反应条件下（常压，460℃左右），可以将甲烷选择性地一次氧化成为甲醇。     

非等温甲烷蒸汽转化反应催化剂的效率因子

本文将环柱状甲烷蒸汽转化催化剂简化为周边封闭的薄片状催化剂,建立了非等温效率因子的计算模型并用正交配置法求解。计算结果合理,计算速度快。     

Methane Oxyforming for Synthesis Gas Production

This article is concerned with the reforming of methane to synthesis gas; a review of the steam reforming Rxn is presented, and the dry reforming and partial oxidation Rxns introduced. Collectively, these processes are known as “oxyforming.” A background to oxyforming, industrial practice, and some of the most important latest developments will be presented, along with a section on the uses of synthesis gas. The current understanding of the Rxn mechanisms for the three processes and the problem of deactivation by carbon deposition will be discussed in detail. Finally, the economics of synfuel production will be addressed and compared with the production of other fuels, and the future directions and outlook for oxyforming will be forwarded. This article should allow the reader to make comparisons between these three important industrial reactions.     

Methane Oxyforming for Synthesis Gas Production

This article is concerned with the reforming of methane to synthesis gas; a review of the steam reforming Rxn is presented, and the dry reforming and partial oxidation Rxns introduced. Collectively, these processes are known as “oxyforming.” A background to oxyforming, industrial practice, and some of the most important latest developments will be presented, along with a section on the uses of synthesis gas. The current understanding of the Rxn mechanisms for the three processes and the problem of deactivation by carbon deposition will be discussed in detail. Finally, the economics of synfuel production will be addressed and compared with the production of other fuels, and the future directions and outlook for oxyforming will be forwarded. This article should allow the reader to make comparisons between these three important industrial reactions.     

低温相变储能材料及其应用

人类对能源的需求日益增加,但是能量利用率不高的问题难以解决。相变储能技术在能源的合理利用、各行业的技术升级与人类生活品质提升的过程中都发挥了重要作用。对相变材料进行了分类并归纳了不同类别相变材料的机理、性能以及其优劣势。根据低温相变储能材料的应用实例归纳了相变储能材料的四大功能:能量调配,温度控制,能量吸收与记忆储存。对相变材料的研究及其发展方向提出相关建议。     

Catalytic Performance of Coal Char for the Methane Reforming Process

A new concept of combined coal gasification and methane reforming in a single reactor was proposed as an alternative path for syngas production using coal and coalbed methane. Here, the results of this process are summarized. The experimental work was carried out in a fixed‐bed reactor. Methane cracking, CO₂/steam reforming of methane over coal char, and the effects of chars made from different types of parent coal on methane conversion were examined. The catalytic effect of coal char on methane cracking and reforming increased with decreasing coalification degree. A synergistic effect was observed in that, while the coal char catalyzed the methane reforming reactions, gasification of the coal char took place simultaneously, which counter‐balanced the deposition of carbon especially for the methane‐steam‐char system.     

甲烷无氧芳构化强化措施

综述了在Mo/HZSM-5上加入第二活性金属组分(如过渡金属、贵金属、稀土金属等)、采用不同的方法对载体进行修饰、改性(如分子筛脱铝、碱处理、二次合成、硅烷化处理等)以及在甲烷中添加其他气体组分(如低碳烃、CO、H_2、CO_2、NO_x及水蒸气)等强化措施对甲烷无氧芳构化的影响。指出未来仍需进一步研究寻求性能更好的催化剂,活性更高的气体添加组分,以及其他可行有效的工艺来降低反应温度,提高甲烷转化率、芳烃收率和催化剂的抗积碳能力。