Thermodynamic stability of hydrogen+tetra-n-butyl phosphonium bromide mixed semi-clathrate hydrate

Three-phase equilibrium (pressure–temperature) relation of hydrate+aqueous+fluid phases for the hydrogen (H₂)+tetra-n-butyl phosphonium bromide (TBPB)+water ternary system was investigated in a temperature range of 281.90–295.94 K and a pressure range up to 170 MPa. The behavior of the three-phase coexisting curve indicates no structural transition in the present experimental region. The Raman spectra obtained in the H₂+TBPB mixed semi-clathrate hydrate crystal reveal that H₂ molecule occupies only small cage compartmentally and the TBPB molecule is encaged with a set of other large cages.     

四丁基溴化铵-二氧化碳-水体系半笼水合物相平衡数据的测定

水合物相平衡数据是利用水合物捕集二氧化碳的基础数据,利用定容逐步加热的方法测量了四丁基溴化铵-二氧化碳-水三元体系水合物的相平衡数据,实验测量的压力和温度分别为1.0-4.3 MPa,282.75-292.15 K,四丁基溴化铵水溶液的质量分数为5％ -30％.实验结果表明:在一定的温度条件下,与纯水中二氧化碳水合物形...     

TBAB和CP双添加剂水合物法分离烟气中的CO2

在四正丁基溴化铵（TBAB）和环戊烷（CP）双添加剂体系下进行了一级水合物法分离烟气中CO2的研究。对比了纯体系和双添加剂体系对水合物生成过程及分离效果的影响。获得了合适的操作条件（温度276.15 K,压力2.0～3.3 MPa）、初始液气比（0.78）、添加剂浓度（CP体积分数为0.6%）。在合适条件下,双添加剂体系相比纯TBAB体系水合过程的载气量达至1.5～2.0倍,剩余气相中CO2摩尔分数由17%降至7%,去除率由40%～50%上升到60%～70%。实验表明,双添加剂体系在水合物法CO2分离技术的分离效果及节能方面存在潜力,为工业化水合物法净化烟气提供了参考和标准。     

Use of an artificial neural network algorithm to predict hydrate dissociation conditions for hydrogen+water and hydrogen+tetra-n-butyl ammonium bromide+water systems

In this communication, a feed-forward artificial neural network algorithm is developed to estimate the hydrate dissociation conditions for the hydrogen+water and hydrogen+tetra-n-butyl ammonium bromide+water systems. To develop this algorithm, the experimental data reported in the literature for hydrate dissociation conditions of the latter two systems with different concentrations of tetra-n-butyl ammonium bromide in aqueous phase below its stoichiometric concentration (i.e., ≈0.037 mole fraction or 0.43 mass fraction) have been used. Independent experimental data (not used in training and developing this algorithm) have been employed to examine the reliability of this method. It is shown that the predicted and the experimental data are in acceptable agreement demonstrating the reliability of this algorithm as a predictive tool.     

A kinetic study of methane hydrate formation

The kinetics of methane hydrate formation, after commencement of nucleation, were studied using a semibatch stirred tank reactor. The temperatures studied in the experiments were from 274 to 284 K over a pressure range of 3–10 MPa. The results of the experiments revealed that the formation kinetics were dependent on the interfacial area, pressure, temperature and degree of supercooling. The history of water sample affected the induction delay times for nuclei formation, but it had no observable effects on the overall kinetics of hydrate formation after the nucleation had commenced. A consistent semi-empirical model was formulated to correlate the experimental kinetic data.     

表面活性剂在瓦斯水合物生成过程中的热力学作用

在实验研究基础上,结合表面活性剂水溶液中瓦斯水合物生成微观机理,提出了表面活性剂改变水合物生成热力学条件物理作用假说,认为表面活性剂胶束对溶于其中的气体分子和吸附于其周围的水分子的束缚作用,相当于降低了体系的温度.利用T40（0.001 mol·L^-1）、T40（0.002 mol·L^-1）、T40/T80（0.001 mol·L^-1）分别组成的3种气 液 煤 水合物反应体系实验测定了水合物生成时的相平衡参数,与同样温度和压力条件下相平衡计算值比较,结果表明,表面活性剂的加入有效地改变了水合物生成的热力学条件.例如,在T40/T80（0.001 mol·L^-1）实验体系中,当压力为22.67 MPa时,水合物生成相平衡温度为22.6℃,比纯水中提高2.1℃.     

Hydrogen storage in trimethylamine hydrate: Thermodynamic stability and hydrogen storage capacity of hydrogen+trimethylamine mixed semi-clathrate hydrate

The thermodynamic stability and hydrogen occupancy for the hydrogen+trimethylamine mixed semi-clathrate hydrate system were investigated by means of phase equilibrium (pressure–temperature) measurements and Raman spectroscopic analyses. The hydrogen molecule gradually advanced to occupy the empty small cage of trimethylamine hydrate in proportion to pressure increase. Almost all small cages were filled up with the hydrogen molecules at about 80 MPa. Isothermal Raman spectroscopic analysis showed that the absorption-rate of hydrogen to the pre-treated trimethylamine hydrate was comparable to those of tetrahydrofuran hydrate. Only one hydrogen molecule was enclosed with one small cage at the equilibrium state in pre-treated trimethylamine hydrate.     

SDS对甲烷水合物生成动力学和微观结构的影响

表面活性剂是促进水合物生成的有效手段之一。在高压反应釜中研究了十二烷基硫酸钠（SDS）对水合物生成过程的动力学影响,利用XRD和拉曼光谱探究了SDS存在条件下水合物的微观结构。宏观结果表明SDS缩短了诱导时间,加快了水合物生长速率。微观结果表明SDS没有影响sI型水合物的晶型结构,晶面间距与理想sI型水合物及纯水甲烷对比误差在千分之几。水合物中甲烷在大笼小笼中的拉曼位移分别为2904和2915 cm^-1,SDS没有改变大笼小笼结构。大笼绝对占有率（q_L）接近饱和时,SDS可以进一步提高小笼绝对占有率（q_S）,从微观角度证明了SDS可以减少水合数,提高储气率。     

A comprehensive review of the effect of different kinetic promoters on methane hydrate formation

Gas hydrates have recently emerged as a better alternative for the production, storage, and transportation of natural gases. However, factors like slow formation rate and limited storage capacity obstruct the pos-sible industrial application of this technique. Different types of promoters and synergists have been developed that can improve the kinetics and storage capacity of gas hydrates. This review focuses on dif-ferent kinetic promoters and synergists that can be utilized to enhance the storage capacity of hydrates. The main characteristics, structure and the possible limitations of the use of these promoters are likewise portrayed in detail. The relationship between structure and storage capacity of hydrates have also been discussed in the review. Current status of production of gas from hydrates, their restrictions, and future difficulties have additionally been addressed in the ensuing areas of the review.     

煤层气水合物定容生成实验研究

为了有效利用与回收直接排放的大量抽放瓦斯,提出了利用水合物技术处理与储运的新方法,根据气体成分确立了水合物生成的温度与压力条件,通过对气体进行初始压力为9.5 MPa的定容法实验,研究了含表面活性剂下水合物生成过程中温度-压力与CH4转化率的变化规律。实验结果表明,水合反应的进行应保持一定的反应驱动力,根据不同温度下反应驱动力进而确定最佳反应条件,同时反应过程中CH4能被有效提取,但要进行高效生产,应进行多级水合分离技术以提高产率。     

基于十六烷基三甲基溴化铵增敏效应电化学方法检测盐酸二甲双胍

在p H 10.0的磷酸盐缓冲溶液中,以单壁碳纳米管修饰的玻碳电极作为工作电极检测盐酸二甲双胍,在电位0.20 V处表现出一对可逆性较好的氧化还原峰。在此基础上,为了进一步提高检测灵敏度,考察了不同类型的表面活性剂对盐酸二甲双胍电化学行为的影响。结果表明,通过在检测液中添加阳离子表面活性剂十六烷基三甲基溴化铵可以显著提高检测的灵敏度,并在表面活性剂存在下,用方波脉冲伏安法实现了盐酸二甲双胍的电化学测定,其响应电流与盐酸二甲双胍浓度在0.2~5 mmol/L范围内呈现良好的线性关系,与先前无表面活性剂存在下建立检测盐酸二甲双胍的电化学方法相比,检测限降至30μmol/L。并利用该电化学传感器对加标血浆样品进行检测,回收率较好。该方法为简便、迅速测定盐酸二甲双胍提供了一种新思路。     

基于十六烷基三甲基溴化铵增敏效应电化学方法检测盐酸二甲双胍

在p H 10.0的磷酸盐缓冲溶液中,以单壁碳纳米管修饰的玻碳电极作为工作电极检测盐酸二甲双胍,在电位0.20 V处表现出一对可逆性较好的氧化还原峰。在此基础上,为了进一步提高检测灵敏度,考察了不同类型的表面活性剂对盐酸二甲双胍电化学行为的影响。结果表明,通过在检测液中添加阳离子表面活性剂十六烷基三甲基溴化铵可以显著提高检测的灵敏度,并在表面活性剂存在下,用方波脉冲伏安法实现了盐酸二甲双胍的电化学测定,其响应电流与盐酸二甲双胍浓度在0.2⁵ mmol/L范围内呈现良好的线性关系,与先前无表面活性剂存在下建立检测盐酸二甲双胍的电化学方法相比,检测限降至30μmol/L。并利用该电化学传感器对加标血浆样品进行检测,回收率较好。该方法为简便、迅速测定盐酸二甲双胍提供了一种新思路。     

聚乙烯己内酰胺链端改性及其对甲烷水合物形成的抑制作用研究

注入动力学抑制剂是一种有效缓解天然气水合物管道堵塞的方法。本文以动力学抑制剂聚乙烯基己内酰胺(PVCap)结构为基础,将氧乙基和酯基引入PVCap的分子链端,合成了新抑制剂PVCap-XA1,在高压定容反应釜内评价了PVCap-XA1对甲烷水合物形成的抑制作用,并采用粉末X射线衍射、低温激光拉曼光谱和冷冻扫描电子显微镜研究了抑制剂对甲烷水合物结构和形态的影响。实验结果表明,相同实验条件下PVCap-XA1比PVCap具有更好的抑制作用;微观测试表明PVCap-XA1的加入没有改变甲烷水合物的晶体结构,但会使甲烷水合物晶面扭曲变形,可以降低水合物大小笼占有比(I_L/I_S),使得甲烷分子更难进入水合物大笼,同时PVCap-XA1的加入使甲烷水合物的微观形貌由多孔有序变得更致密而不利于气体通过。     

四乙基溴化铵和十八烷基三甲基氯化铵协同作用下有机改性蒙脱石制备工艺条件研究

本文对四乙基溴化铵和十八烷基三甲基氯化铵协同作用下有机改性蒙脱石制备工艺条件进行了研究,在十八烷基三甲基氯化铵(1831)对钠基蒙脱石有机改性过程中加入四乙基溴化铵可以明显改善有机化效果.最佳的单因素条件为:有机改性前半小时加入四乙基溴化铵,加入量3g/25g土,改性温度80℃,改性时间2h,矿浆pH值不需要调节.四因素交互作用最佳有机改性工艺条件为:四乙基溴化铵用量2g/25g土,有机化温度80℃,有机化时间1h,矿浆pH值9.95.对应最优组合A2B3C1D2实验条件制备的有机蒙脱石的d001值高达63.9652A,实验产品烧失量最高为29.18%.     

The effect of the additive cetyl trimethyl ammonium bromide on the electrodeposition of lead dioxide

The electrodeposition of lead dioxide on graphite substrates was studied earlier. In this work rotation or oscillation of the anode was employed to get a smooth and adherent deposit, free from pinholes. The influence of the addition of cetyl trimethyl ammonium bromide (CTAB), a cationic surfactant, to the bath during the electrodeposition of lead dioxide has been studied in the present work. It has been found that the addition of the surfactant not only gives a smooth and adherent deposit free from pinholes under stationary condition but also permits the use of higher current densities during deposition.The throwing power, conductivity and surface tension of the bath have been measured. The internal stress in the electrodeposit and anode potential measurements in the presence of CTAB are also reported.Studies on the effect of other quaternary ammonium surfactants like tetradecyl and dodecyl trimethyl ammonium bromides on the deposition of lead dioxide are also incorporated.     

Physicochemical investigation of the decomposition products of ammonium metal carboxylates: ammonium ferric citrate hydrate

The thermal decomposition up to 400 °C of ammonium ferric citrate hydrate, of unknown structure and formula weight, was studied by thermogravimetry, differential thermal analysis, infrared (IR) spectroscopy and X-ray diffractometry. The possible identities of the formula weight and the intermediate products of calcination are discussed. The results revealed that the parent material is amorphous and contains two moles of water and two moles of ammonia. Decomposition takes place via six weight-loss processes, three endothermic (90–230 °C) and three exothermic (240–298 °C), leading eventually to the formation of Fe₂O₃. The intermediate solid products are mainly unstable amorphous oxycarbonates, as indicated by X-ray and IR spectroscopies. The gas-phase decomposition products identified by IR spectroscopy are NH₃, CO₂, CO, CH₃COCH₃, CH₄ and NH₄OH. Surface area measurement and scanning electron microscopy showed that Fe₂O₃, the final product at 400 °C, hada surface area of 40 m²/g and good crystalline and porous character.     

泡沫铜强化甲烷水合物生成动力学实验研究

提高水合物生成速率和储气密度对天然气水合物技术应用非常重要。将三种孔密度的泡沫铜（CF）分别浸入十二烷基硫酸钠（SDS）溶液中构建水合储气强化体系,在高压静态反应釜中研究泡沫金属对甲烷水合物生成动力学特性。实验结果表明,泡沫铜骨架能为水合物生成提供充足的结晶点,同时可作为水合物生长过程水合热迁移的“高速公路”。甲烷水合物在SDS/CF体系中可快速生成,最大水合储气速率分布在19.24~21.04 mmol·mol^-1·min^-1之间,其中添加15 PPI泡沫铜的SDS溶液储气量最高（139 mmol·mol^-1）,且达到最大储气量90%所用时间最短（10.1 min）。在6.0~8.0 MPa压力下,相比SDS溶液,添加15 PPI泡沫铜的SDS溶液储气量提高了8.8%~35.6%,储气速率提高了4.7%~40.4%;特别在压力为5.0 MPa时,该孔密度SDS/CF体系储气量甚至比SDS溶液增加13倍,储气速率增加16倍。     

饱和溶液对天然气水合物影响的实验研究

水合物生成速度及储气量严重制约着天然气以水合物形式储运的发展。为提高其生成速度及储气量,采用饱和溶液提供晶种代替水合物晶核自发形成的方式,研究了不同饱和度CuSO_4溶液、MgSO_4溶液及去离子水在8.45MPa,温度分别为3,5,8℃条件下对天然气水合物生成速度及储气量的影响。由结果可知:饱和溶液可以促进天然气水合物生成。相同实验条件下,CuSO_4饱和溶液生成水合物的储气量是去离子水的7倍,MgSO_4饱和溶液生成水合物的储气量是去离子水的7.2倍,水合物在饱和溶液中的生成速度也明显提高。饱和溶液中天然气水合物生成的初始阶段主要受饱和溶液结晶作用影响,降低温度可以改变水合物的平衡压力,影响水合物的平均生成速度,但对水合物初期的生成速度影响不大。     

卵磷脂对甲烷水合物形成的影响

建立了用于测定卵磷脂(lecithin)对钻井液中水合物形成影响的实验装置及方法,以理解化学添加剂卵磷脂对北极Cascade地区钻井过程中水合物层的稳定作用。本研究旨在理解卵磷脂对纯水中甲烷水合物形成热力学和动力学的影响。结果表明,卵磷脂基本上不影响甲烷水合物生成的热力学条件,但当卵磷脂在水中的浓度超过0.003 g·g^-1时,它会影响甲烷水合物的生成速度和数量,是很好的水合物生成动力学促进剂。     

泡状流中水合物生成预测模型及实验

针对可燃冰钻采井筒内易发生水合物生成和堵塞的工程问题,本文开展了泡状流条件下甲烷水合物生成实验,发现流速增加会提高水合物生成速率,黄原胶质量分数的增加会降低水合物生成速率。基于传质理论,构建了适用于可燃冰钻采井筒内泡状流条件下水合物生成预测模型,模型考虑了连续相流体流变性、气泡破裂、聚并和形变等因素对泡状流中气液界面分布和气液间传质规律的影响,并耦合实验数据,提出了气泡群间的综合传质系数经验公式,用于描述气泡间相互作用对气液间传质速率的影响。对比实验结果,所建立模型对水合物生成量和水合物生成速率的预测误差分别在±5%和±15%以内,满足工程计算需求。该模型的构建有助于精准预测油气和可燃冰钻采井筒内水合物风险,为建立经济、高效的井筒水合物防治方案奠定理论基础。