Bubble point pressures and densities of hexamethyldisiloxane–carbon dioxide binary mixture using a constant volume view cell

The phase behavior of hexamethyldisiloxane (HMDS)–carbon dioxide (CO₂) binary mixture was investigated using a constant volume view cell. The accuracy of the measurement technique was inspected against the bubble point pressure data in the literature for ethanol (C₂H₅OH)–carbon dioxide (CO₂) binary mixture. The bubble point pressures for C₂H₅OH–CO₂ agreed well with the literature values. The bubble point pressures of HMDS–CO₂ binary mixture were determined at five different temperatures (T = 298.2 K, 308.2 K, 313.2 K, 323.2 K, 333.2 K) and at various compositions. The bubble point pressures increased with increasing temperature and CO₂ mole fraction in the binary mixture. The phase behavior of the binary mixture was modeled using the Peng–Robinson Stryjek–Vera equation of state (PRSVEoS). The binary interaction parameters were regressed from experimental bubble point pressures at each temperature and were found to exhibit a linear dependency on temperature. The HMDS–CO₂ binary mixture was also found to exhibit Type II phase behavior. Additionally, P–T–ρ measurements for the same binary system were conducted and excess molar volumes were calculated.     

Demixing pressures of hydroxy-terminated poly(dimethylsiloxane)–carbon dioxide binary mixtures at 313.2 K, 323.2 K and 333.2 K

The phase behavior of PDMS(OH)–CO₂ binary mixtures was investigated. Two different molecular weight PDMS(OH) were utilized and the demixing pressures were determined at three temperatures for a wide composition range. Both of these polymers were found to form miscible mixtures with CO₂ at all compositions at pressures lower than 31 MPa in the temperature range 313.2–333.2 K. Depending on the composition of the binary mixtures, two types of phase separation was observed during depressurization; the bubble point and the cloud point. In addition, at specific weight fractions a color change was also observed which was attributed to the mixture critical point. The demixing pressures were observed to increase with temperature and decrease with increasing polymer weight fraction. In addition, higher demixing pressures were obtained for the higher molecular weight polymer mixtures. The bubble point data were modeled by using Sanchez–Lacombe equation of state (SLEoS) and the binary interaction parameters were regressed at the studied temperatures. It was observed that the binary interaction parameters decreased with increasing temperature.     

High-pressure phase behavior of carbon dioxide in ionic liquid 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide

Phase equilibrium data of carbon dioxide in the ionic liquid 1-butyl-3-methyl-imidazolium bis(trifluoromethylsulfonyl)imide ([bmim][Tf₂N]) are presented at high pressures up to about 30 MPa and at temperatures between 298.15 K and 343.15 K. The solubilities at a given temperature were determined by measuring the bubble point pressure of the ionic liquid solution with carbon dioxide dissolved using the high-pressure equilibrium apparatus equipped with a variable-volume view cell. Solubility results are reported for carbon dioxide concentrations ranging from 0.21 up to 0.80 mole fraction. Carbon dioxide gave very high solubilities in the ionic liquid at lower pressures, while the equilibrium pressure increased very steeply at higher concentrations of carbon dioxide. The solubility of carbon dioxide in the ionic liquid decreased with an increase in temperature.     

Effect of confinement on the bubble points of hydrocarbons in nanoporous media

The bubble point of reservoir petroleum fluids in nanoporous media is an important parameter in shale oil production. We present experimental results on the bubble points of octane and decane confined in controlled‐pore glasses (CPGs) with pore sizes of 4.3 and 38.1 nm. Differential scanning calorimetry (DSC) is used to measure the temperature at which the vapor phase begins to form (i.e., the bubble point). We find that the bubble point is dramatically affected by pore diameter: at 38.1 nm the confinement effect is insignificant, but at 4.3 nm two distinct bubble points appear, suggesting two distinct populations of evaporating fluid. Deviations are as great as ±15 K for both peaks relative to the bulk bubble point for 4.3 nm CPGs. Thermogravimetric analysis is consistent with DSC, supporting the validity of these results. Based on these experiments and previous simulations, we propose a two‐state model for the nanoconfined hydrocarbons. © 2016 American Institute of Chemical Engineers AIChE J, 62: 1772–1780, 2016     

Surface modification of silica aerogels by hexamethyldisilazane–carbon dioxide mixtures and their phase behavior

The surfaces of monolithic silica aerogels were rendered hydrophobic using hexamethyldisilazane (HMDS) as surface modification agent and scCO₂ as solvent. The treatment led to hydrophobic silica aerogels which are as transparent as untreated aerogels. The effects of HMDS concentration in the fluid phase and the reaction time were investigated and the contact angles were found to be 130° at different conditions. FTIR spectra indicated a reduction in hydrophilic surface silanol groups and the emergence of hydrophobic CH₃ groups. The bubble point pressures of the HMDS–CO₂ system were obtained at temperatures 298.2 K, 313.2 K, 327.7 K and 342 K at various concentrations. At a fixed temperature, the bubble point pressure decreased as the concentration of HMDS increased. At a fixed composition, bubble point pressure increased as the temperature increased. The bubble point pressures were modeled using the Peng–Robinson Stryjek–Vera Equation of State (PRSVEOS) and compared well with the experimental data.     

油页岩热解特性及其甲烷释放规律研究

为研究油页岩热解特性及热解过程中甲烷的释放规律,采用热重-傅里叶变换红外光谱（TG-FTIR）对龙口（LK）、内蒙（NM）、汪清（WQ）三个地区的典型油页岩进行热解实验,并结合固相红外（FTIR）对油页岩的官能团结构进行分析。研究结果表明,油页岩热解过程可分为四个阶段,热解反应及挥发分释放主要发生在第二阶段（400～600℃）。甲烷的析出与油页岩结构中的脂肪烃（光谱范围3000～2800 cm^-1）密切相关,脂肪烃含量越多,热解过程中释放的甲烷越多。通过对甲烷析出曲线分峰拟合及结合动力学分析,得出甲烷的生成是由一个脱吸附过程和四个化学反应共同作用的结果。     

Measurement and thermodynamic modeling of partition coefficients in N,N-dimethylacetamide-water-carbon dioxide system

The partition coefficients of N,N-dimethylacetamide (N,N-DMA) between the water and the supercritical and near-critical carbon dioxide (CO₂) phases were measured in the temperature range of 298.15-328.15 K and the pressure range of 8.3-24.1 MPa. The measurements were carried out in a 56 ml vessel by contacting the carbon dioxide and the aqueous phases. The partition coefficients of N,N-DMA increased from 0.05 to 0.150 with increasing pressure at a constant temperature and increased with temperature at a constant density. The bubble point pressures of N,N-DMA-CO₂ mixtures were measured at 298.15 K, 308.15 K and 318.15 K and were found to increase with increasing mole fraction of CO₂. The partition coefficients were modeled using the Peng-Robinson Equation of State (PREOS) combined with modified van der Waals mixing rule. The binary interaction parameters for the CO₂-H₂O pair were taken from the literature and were regressed for CO₂-N,N-DMA and H₂O-N,N-DMA pairs by fitting partition coefficients data. The binary interaction parameter for CO₂-N,N-DMA pair was found to depend linearly on temperature. The bubble point pressures of N,N-DMA and CO₂ were also measured and could be predicted fairly well using the regressed binary interaction parameters.     

Potassium catalysed gasification of Kentucky oil shale char

The steam gasification of a Kentucky oil shale char has been studied in a semi-batch fixed bed reactor. The effects of temperature (973–1173 K), catalyst loading (0–15% K₂CO₃) and pressure (up to 0.65 MPa) on the gasification rates and make-gas composition have been determined. Although gasification rates were increased by a factor of about three in the presence of 10% K₂CO₃, they were still significantly lower than those previously measured with western shale chars. The reason for this could be attributed to the relatively high hydrogen concentrations produced in the fixed-bed configuration since severe hydrogen inhibition has been previously reported for a similar shale char. There was no significant effect of the potassium catalysis on either the make-gas composition or the quantities of sulphur released during gasification. The only significant influence of pressure was to increase the methane make and this was independent of the catalyst loading.     

Physical behaviour of oil shale at various temperatures and compressive loads: 1. Free thermal expansion

The effects of grade and specimen orientation on the free thermal expansion of oil shale were investigated. The expansion was found to increase with the grade of the specimen and to be dependent on orientation. The change in heating rate from 1.0 K min⁻¹ to 3.5 K min⁻¹ had little effect on the expansion of oil shale. It was found that many of the oil shale specimens would settle under their own weight once kerogen left the oil shale. The thermal expansion coefficients in the temperature range 373–473 K were determined to be little affected by increases in grade. A polynomial correlation of expansion versus grade and temperature in the temperature range 298–698 K is presented. The behaviour at temperature up to 1000–4000 K was also investigated.     

Measurement of bubble point pressures and critical points of carbon dioxide and chlorodifluoromethane mixtures using the variable-volume view cell apparatus

The bubble point pressures and the critical points of carbon dioxide (CO₂) and chlorodifluoromethane (HCFC-22) mixtures were measured by using a high-pressure experimental apparatus equipped with a variable-volume view cell, at various CO₂ compositions in the range of temperatures above the critical temperature of CO₂ and below the critical temperature of HCFC-22. The experimental bubble point pressure data were correlated with the Peng-Robinson equation of state (PR-EOS) to estimate the corresponding dew point compositions at equilibrium with the bubble point compositions. The experimentally measured bubble point pressures and the mixture critical points gave good agreement with those calculated by the PR-EOS. The variable-volume view cell equipment was verified to be an easy and quick way to measure the bubble point pressures and the mixture critical points of high-pressure compressible fluid mixtures.     

Effect of the presence of organic matter on bubble points of oils in shales

The relative amounts of oil and gas produced in prolific plays like the Eagle Ford are affected by the oil bubble point. The oil and kerogen (organic matter) are found in the same rock and the oil may remain in contact with the kerogen. Bulk experiments and molecular simulations clearly show that kerogen preferentially absorbs hydrocarbons. The absorbed oil phase remains in multi‐component equilibrium with the expelled oil produced at the surface. Results from a model proposed to calculate the bubble points (at 400 K) of in situ oils (absorbed + free) in the presence of kerogen indicate suppression of about 4150–16,350 kPa from the original value of 28,025 kPa of produced Eagle Ford oil. These calculations depend on the type and level of maturity of kerogen. The prediction of accurate saturation pressures has key implications on volumes of recovery and rates of production from liquid rich shales. © 2017 American Institute of Chemical Engineers AIChE J, 63: 3083–3095, 2017     

油母页岩粉体的结构改性及其应用

研究了油母页岩粉体由晶体结构转变为无定形结构的方法,讨论了KOH质量分数、乙酸钾质量分数及二甲基亚砜对油母页岩粉体结构的影响,考察了无定形油母页岩粉体增强天然橡胶的力学性能。结果表明,在乙酸钾和KOH的协同作用下,油母页岩粉体由晶体结构转变为无定形结构;当KOH质量分数为8%、乙酸钾质量分数为45%时,油母页岩粉体的无定形转变率最高;二甲基亚砜先插入油母页岩粉体层间,再与质量分数为10%的KOH溶液作用,也可以使油母页岩粉体由晶体结构转变为无定形结构;质量分数为8%的KOH和质量分数为45%的乙酸钾协同改性油母页岩粉体填充天然橡胶复合材料的力学性能显著提高,而二甲基亚砜和KOH协同改性的油母页岩粉体填充天然橡胶复合材料的力学性能除撕裂强度显著提高外,其他力学性能没有显著变化,还需对无定形油母页岩粉体中新出现的尖锐毛刺进行表面钝化和有机改性,以体现无定形油母页岩粉体对天然橡胶的增强作用。     

层柱黏土催化剂在页岩油加氢裂化中的研究

实验以Al-PILM,FeAl-PILM,β沸石和Y型分子筛为载体制备了NiW加氢裂化催化剂,对页岩油全馏分进行加氢裂化催化实验.对所得的产品油于实沸点蒸馏装置上进行馏分切割,并对各个馏分进行分析.结果表明:四种催化剂对页岩油都有明显的加氢裂化性能,轻馏分的收率较原油有很大提高,最高收率分别,<160℃为2.8%,16...     

Extraction of El-Lajjun Oil Shale

Abstract

Extraction of the bitumen fraction of El-Lajjun oil shale was carried out using 17 different solvents, pure and combined. Out of all the solvents used, toluene and chloroform were found to be the most efficient for extraction of the bitumen to perform the major part of the experiments. This selectivity was based on the quality and quantity of the yield and on the quantity of solvent recovered. Extraction was carried out using a Soxhlet extractor. For complete recovery of solvent the extract phase was subjected to two stages of distillation, simple distillation followed by fractional distillation, where different cuts of oil were obtained. It was found that an optimum shale size of 1.0 mm offered better solvent recovery. One hour was the optimum time needed for complete extraction. The yield of oil was determined from the material balance gained from fractional distillation after testing for the existence of any traces of solvent trapped in the different cuts by using a gas chromotography technique. When chloroform was used, it was found that the average amount of bitumen extracted was 0.037 g/g of shale, which corresponds to 98% of the actual bitumen trapped in the oil shale (by assuming the bitumen represents 15% of the organic matter) and 84.1% of solvent recovered. When toluene was used, it was found that the average amount of oil extracted was 0.0293 g/g of shale, which corresponds to 78% of the actual bitumen trapped in the oil shale (by assuming bitumen represents 15% of the organic matter) and 89.9% of solvent for extraction with toluene.     

Calorimetric determination of the heat of retorting oil shales to 773 K

The heat of retorting raw oil shale from 298 to 773 K was determined using a Calvet-type, high-temperature calorimeter. Samples from a float and sink separation procedure were used to span a wide range of kerogen/mineral contributions: Colorado Green River shale, 87–340 1 tonne⁻¹; Australian Rundle shale, 33–255 1 tonne⁻¹. Small samples (40–100 mg) of dried shale powder were dropped into the calorimeter at 773 K, producing an endothermic peak in the thermopile signal. The height of the peak is a measure of the enthalpy of rapid processes (~ 120–180 s), while the peak area gives the total enthalpy over the entire run (~ 1.3–1.5 h). Besides the quantitative enthalpy values obtained, a comparison of the peak-height and peak-area values is a measure of the duration of the processes occurring in the samples upon rapid heating to 773 K. This comparison for the Rundle shale indicates slower inorganic processes occurring at this temperature.     

Solubility of carbon dioxide in ammonium-based ionic liquids: Butyltrimethylammonium bis(trifluoromethylsulfonyl)imide and methyltrioctylammonium bis(trifluoromethylsulfonyl)imide

Solubility results of carbon dioxide (CO₂) in two ammonium-based ionic liquids, butyltrimethylammonium bis(trifluoromethylsulfonyl)imide ([N4,1,1,1][Tf₂N]) and methyltrioctylammonium bis(trifluoromethylsulfonyl)imide ([N1,8,8,8][Tf₂N]), are presented at pressures up to approximately 45 MPa and temperatures ranging from 303.15 K to 343.15 K. The solubility was determined by measuring bubble point pressures of mixtures of CO₂ and ionic liquid using a high-pressure equilibrium apparatus equipped with a variable-volume view cell. Sharp increase of equilibrium pressure was observed at high CO₂ compositions. The CO₂ solubility in ionic liquids increased with the increase of the total length of alkyl chains attached to the ammonium cation of the ionic liquids. The experimental data for the CO₂+ionic liquid systems were correlated using the Peng-Robinson equation of state.     

Modeling viscosity of methane,nitrogen, and hydrocarbon gas mixtures at ultra-high pressures and temperatures using group method of data handling and gene expression programming techniques

Accurate gas viscosity determination is an important issue in the oil and gas industries. Experimental approaches for gas viscosity measurement are time-consuming, expensive and hardly possible at high pressures and high temperatures (HPHT). In this study, a number of correlations were developed to esti-mate gas viscosity by the use of group method of data handling (GMDH)-type neural network and gene expression programming (GEP) techniques using a large data set containing more than 3000 experimen-tal data points for methane, nitrogen, and hydrocarbon gas mixtures. It is worth mentioning that unlike many of viscosity correlations, the proposed ones in this study could compute gas viscosity at pressures ranging between 34 and 172 MPa and temperatures between 310 and 1300 K. Also, a comparison was performed between the results of these established models and the results of ten well-known models reported in the literature. Average absolute relative errors of GMDH models were obtained 4.23％, 0.64％, and 0.61％for hydrocarbon gas mixtures, methane, and nitrogen, respectively. In addition, graph-ical analyses indicate that the GMDH can predict gas viscosity with higher accuracy than GEP at HPHT conditions. Also, using leverage technique, valid, suspected and outlier data points were determined. Finally, trends of gas viscosity models at different conditions were evaluated.     

Phase equilibrium data and thermodynamic modeling of the system propane + NMP + methanol at high pressures

This work reports phase equilibrium data at high pressures for the binary and ternary systems formed by propane + n-methyl-2-pyrrolidone (NMP) + methanol. Phase equilibrium measurements were performed in a high-pressure variable-volume view cell, following the static synthetic method for obtaining the experimental bubble and dew points transition data in the temperature range of 363-393 K, pressures up to 16 MPa and overall molar fraction of the lighter component varying from 0.1 to 0.998. For the systems investigated, vapor-liquid (VLE), liquid-liquid (LLE) and vapor-liquid-liquid (VLLE) phase transitions were visually recorded. Results show that the systems investigated present UCST (upper critical solution temperature) phase transition curves with an UCEP (upper critical end point) at a temperature higher than the propane critical temperature. The experimental data were modeled using the Peng-Robinson equation of state with the Wong-Sandler and the classical quadratic mixing rules, affording a satisfactory representation of the experimental data.     

不同温度压力下丙酮－环己烷体系液体密度的测定和推算

使用ＤＭＡ５５型精密密度计和ＤＭＡ５１２型高压外测量池，测定了丙酮－环己烷体系在温度范围为２８８．１５Ｋ至３１８．１５Ｋ和压力从常压至１９．５１ＭＰａ下的液体密度；建立了一个新的液体混合物密度模型，推算了该体系在不同温度压力下的混合物密度，取得令人满意的结果。     

Secondary coking and cracking of shale oil vapours from pyrolysis or hydropyrolysis of a Kentucky Cleveland oil shale in a two-stage reactor

It is widely recognized that secondary reactions which are mainly associated with minerals during oil shale retorting have a marked influence on the product yields and compositions. To understand these phenomena more clearly, the secondary reactions of shale oil vapours from the pyrolysis (or hydropyrolysis) of Kentucky Cleveland oil shale were examined in a two-stage, fixed-bed reactor in flowing nitrogen or hydrogen at pressures of 0.1–15 MPa. The vapours from pyrolysis (first stage) were passed through a second stage containing combusted shale, upgrading catalyst or neither. Carbon conversion to volatile products in the first stage increased from 49% during thermal pyrolysis to 81% at 15 MPa H₂ partial pressure. During thermal pyrolysis, total pressure had only a slight effect on carbon removal from the raw shale and subsequent deposition on to the porous solids in the second stage. Carbon deposition on to the combusted shale in the second stage was reduced to zero at 15 MPa H₂ partial pressure. The n-alkane distributions of the oils as determined by gas chromatography clearly demonstrated that higher hydrogen pressure, contact with combusted shale, or both contributed to lower-molecular-weight products.