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A series of experimental investigations was carried out to study the kinetics of spontaneous heterogeneous boiling-up of superheated n-pentane in two glass tubes. It was determined that the isobaric temperature dependences of the mean lifetime of the superheated liquid that were measured under similar conditions have threshold values in the temperature ranges of 100–115, 120–125, and 130–140°C. [ABSTRACT FROM AUTHOR]

Copyright of Petroleum Refinery Engineering is the property of Petroleum Refinery Engineering Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This work reports the nucleate boiling heat transfer characteristics of n-pentane on smooth and enhanced surfaces. Surface modifications were carried out on stainless steel surfaces by fabricating microholes of diameter between 0.3 and 0.7 mm arrays using electric discharge machining. Pool boiling experiments were carried out at normal atmospheric pressure. Experiments have been performed for applied effective heat flux range between 1 and 10 W cm−2. An enhancement of 20–45% in heat transfer coefficient was observed on the enhanced surface compared to the smooth surface. The heat transfer improvement in the enhanced surface can be attributed to more active nucleation sites, better rewetting phenomenon, and favorable bubble growth and release mechanism. Further changing the material from steel to brass enhances the heat transfer coefficient by 20%. This will be a viable option as a cooling technology for high-power electronic industries. [ABSTRACT FROM AUTHOR]

The boiling-up kinetics of superheated n-pentane in a glass tube has been studied by means of a high-speed video filming and a fast-acting pressure sensor. The top of the tube is sealed. It is shown that, as the threshold temperature is approached, the boiling-up of a superheated liquid is accompanied by significant pressure jumps and oscillations, whereas the formation of a vapor film can begin from self-organization in the near-wall layer of the liquid. [ABSTRACT FROM AUTHOR]

Flow boiling is a complex process but very efficient for thermal management in different sectors; enhancing flow boiling heat transfer properties is a research field of great interest. This study proposes the use of various nanomaterials, carbon-based materials, and metal oxides; in n-pentane as a hydrocarbon-based refrigerant to enhance the flow boiling heat transfer coefficient. This thermal property has been experimentally evaluated using a vertical evaporation device of glass with an internal diameter of 20 mm. The results have shown that proposed nanomaterials dispersion in n-pentane has a limited effect on the thermophysical properties and is conditioned by their dispersibility but promotes a significant increment of pentane heat transfer coefficient (h), increasing the overall heat transfer coefficient (U) of the evaporator. The enhanced heat transfer performance is attributed to the behavior of nanoparticles under working conditions and their interaction with the working surface, promoting a higher generation of nucleation sites. The observed behavior suggests a heat transfer mechanism transition from forced convection to nucleate heat transfer, supported by visual observations. [ABSTRACT FROM AUTHOR]

In this work, we investigated the effect of Gelatin on the solubility and diffusivity of normal pentane in poly (vinyl alcohol) (PVA)/Gelatin (Gel) blends. The processibility of PVA was enhanced after adding the gelatin as plasticizer to PVA which gelatin could extend the process widow of PVA with destroying the hydrogen bonding of the polymer matrix. Therefore, the PVA/Gel blends with different concentrations were prepared by simple solution-casting method. The intermolecular suitable interactions in PVA/Gel blends were confirmed using the FTIR, XRD and SEM/EDX analyzes. In the following, the effect of various factors like temperature, pressure and gelatin content on the thermodynamic parameters like specific free volume, solubility and diffusivity was investigated. It was shown that there was a relationship between the specific free volume of the blends with the solubility and diffusivity of normal pentane in blends. The specific free volume of blends was determined by applying the PVT data and the Sanchez-Lacombe (SL) equation of state, in which it was enhanced with increasing of the temperature and gelatin in blends, respectively. Also, the solubility and diffusivity of normal pentane in samples were determined by the magnetic suspension balance (MSB) system. The results presented that the solubility and diffusivity of n-pentane improved with increasing of gelatin content in blend, pressure and temperature decrement, respectively. [ABSTRACT FROM AUTHOR]

When converting C5 hydrocarbons to light olefins by catalytic pyrolysis, the generation of low valueadded methane will affect the atomic utilization efficiency of C5 hydrocarbons. To improve the atomic utilization efficiency, different generation pathways of light olefins and methane in the catalytic pyrolysis of C5 hydrocarbons were analyzed, and the effects of reaction conditions and zeolite types were investigated. Results showed that light olefins were mainly formed by breaking the C2-C3 bond in the middle position, while methane was formed by breaking the C1-C2 bond at the end. Meanwhile, it was discovered that the hydrogen transfer reaction could be reduced by about 90% by selecting MTT zeolite with 1D topology and FER zeolite with 2D topology under high weight hourly space velocity (WHSV) and high temperature operations, thus leading to the improvement of the light olefins selectivity for the catalytic pyrolysis of n-pentane and 1-pentene to 55.12% and 74.60%, respectively. Moreover, the fraction ratio of terminal C1-C2 bond cleavage was reduced, which would reduce the selectivity of methane to 6.63% and 1.83%. Therefore, zeolite with low hydrogen transfer activity and catalytic pyrolysis process with high WHSV will be conducive to maximize light olefins and to decrease methane. [ABSTRACT FROM AUTHOR]

The kinetic study of free radical polymerization of styrene in the presence of n-pentane is a challenging and relevant topic because of its commercial and scientific value. Although this reaction has been carried out for decades, its kinetics are not fully understood. Thus, this polymerization is a current research topic mainly focused on the diffusive effects and ways to make more economical and efficient processes. This work presents a study focused on analyzing the kinetic effect of n-pentane addition during the bulk free-radical polymerization of styrene to contribute to the comprehension of phenomena which take place during this reaction. To reach this goal, we extended and implemented a model previously developed by one of the authors to perform the simulation and prediction of experimental data reported in the literature at different reaction conditions and multiple n-pentane amounts. Results obtained with the model allow us to explain the polymerization evolution in terms of the diffusive effects and the explicit theoretical description of the repetitive units that a terminal segment from a long radical involved in the termination stage can move (Usegm). That lets us identify the effects produced by the presence of n-pentane in the theoretical transition region from chemical to diffusive control in the termination reaction. This region is relevant due to its relationship with the increasing polymerization rate and the onset of the auto-acceleration effect. The comparison of the theoretical evolution of the weight-average molecular weight (Mw) against experimental data indicates that to enhance their correlation is necessary to consider not only the solvation effect but also the transfer effect produced by the presence of n-pentane during the polymerization. [ABSTRACT FROM AUTHOR]

Direct production of light olefins, building blocks of chemical industry, can be attained by developing efficient catalysts for Fischer-Tropsch synthesis (FTS). The nature of FTS complicates the catalyst development process as the product distribution is affected by the components and the preparation methods of the catalyst. In this work, high-throughput (HT) methodology is employed to overcome this problem by testing many different catalyst formulations. Fast performance screening of 40 different a-Al2O3 supported Fe-Mn based catalysts promoted with Cu, K and Ni, using different impregnation agents, was performed in a HT test system at atmospheric pressure. Promising catalyst candidates identified by HT analysis were further subjected to high pressure FTS in a conventional system. Results indicate that coupled with Mn, Ni promoted CH4 production, Cu increased CO conversion, K enhanced olefin selectivity and olefin-to-paraffin ratio. In double promotion of Cu and K, Cu balanced the activity and stability loss due to K, while K enhanced olefin selectivity. n-pentane aided impregnation slightly enhanced catalytic performance. Differences observed in catalytic performance were regarded as related to the structural changes caused by promoter and impregnation type based on characterization data obtained by H2-TPR, XRD, SEM, EDS mapping and N2 adsorption. [ABSTRACT FROM AUTHOR]

Recent combustion research has focused on low temperature combustion to meet engine emission regulations and to advance the development of low temperature homogenous compression ignition engines. Autoignition studies in this temperature regime are primarily performed by Rapid Compression Machines (RCMs) which are sensitive to the heat transfer characteristics of the experimental device. RCMs are widely used to measure autoignition data such as ignition delay and species concentration. Measured ignition delays from RCMs are typically reported at an adiabatic condition; however, this assumption may produce a systematic error in ignition delay measurement as heat transfer is observed to reduce the pressure and temperature during the autoignition process, e.g., a longer ignition delay has a greater pressure and temperature drops. RCMs are custom built and have unique design characteristics that affect the heat transfer during the autoignition process. In addition, depending on the diluent composition (e.g., helium versus nitrogen or argon), different heat transfer characteristics are expected. As a result, autoignition results at similar conditions may vary from facility to facility or depending on the used diluent. The dependency of the measured data on the used facility or diluent may produce uncertainty in the data which impact the development of high-fidelity combustion mechanisms. In this work, a new method is developed and utilized to eliminate heat transfer from the ignition delay data. To evaluate the new method, the autoignition of n-pentane mixtures in the low temperature regime were investigated using an RCM. To vary the heat transfer, the compression ratio of the RCM was changed and the ignition delays were measured at similar pressure and temperature conditions. The tests were performed at an equivalence ratio of approximately one and nitrogen and argon as diluents. By applying the new method, the effect of heat transfer on the ignition delays were eliminated successfully and ignition delays at adiabatic condition were determined. A detailed kinetic model of n-pentane was used to simulate the measured adiabatic ignition delay, which agreed well with the experimental data. [ABSTRACT FROM AUTHOR]

A series of ReaxFF reactive molecular dynamic simulations are performed to investigate the combustion of n-pentane, isopentane and neopentane. The effects of temperature and the n-pentane-to-O2 ratio on the number of main radical and molecular products for the combustion of n-pentane are analyzed, the combustion characteristics of n-pentane, isopentane and neopentane are compared, and the spontaneous combustion characteristic of n-pentane is discussed in this work. The results indicated that the main reactions involved in the early stage of n-pentane, isopentane and neopentane combustion are the pyrolysis of these working fluids, and then, O2 molecules are involved in the oxidation reactions. The content of O2 in reaction systems has a very obvious effect on the combustion of n-pentane. With the increase in the O2 content, the consumption rate of n-pentane is significantly accelerated, and the rate of increase in the total fragments number is also significantly increased. Neopentane burns most intensely, followed by isopentane, and finally n-pentane. A faster heating rate will be accompanied by more intense spontaneous combustion of n-pentane and more product formation, which will cause greater harm to the surrounding area. Thus, in order to reduce the possibility of damage caused by leakage combustion of flammable working fluid, the heat source temperature and open flame around the organic Rankine cycle system should be strictly controlled, and some flame retardants are recommended to be added to the working fluid to reduce the flammability while ensuring the economy of the organic Rankine cycle. This study is conducive to the safety of n-pentane, isopentane and neopentane used in industrial fields. [ABSTRACT FROM AUTHOR]

The metal modified ZSM-5 catalysts has been widely used in the aromatization of light alkanes. To investigate the effect of Si/Al ratio of ZSM-5 zeolites, a series of Zn/ZSM-5 catalysts with different Si/Al ratios have been prepared by wet impregnation and tested for n-pentane aromatization. The results indicated that, the introduced Zn species consumed the strong Brønsted acid sites and inhibited the undesired cracking reactions effectively. With the increase of Si/Al ratio of ZSM-5 zeolites, the n-pentane conversion decreased obviously due to the reduced acid content and strength, while the selectivity to BTX remained almost unchanged. Attributed to the weakened cracking and hydrogen-transfer reactions with increasing Si/Al ratio, the selectivity to light alkanes decreased, while that to olefins increased remarkably. Further, the possible reaction pathways have been proposed to better elucidate the changing product distribution with the Si/Al ratios. [ABSTRACT FROM AUTHOR]

Copyright of SDU Journal of Engineering Sciences & Design / Mühendislik Bilimleri ve Tasarım Dergisi is the property of Journal of Engineering Sciences & Design and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Zeitschrift für Physikalische Chemie is the property of De Gruyter and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Energy optimization is performed on hybrid solar-geothermal power plant working according to Organic Rankine Cycle and installed in southern Tunisia. The performances of four different configurations of the power plant are studied. Mass and energy balances are established for the different compounds. The effects of the main operating parameters such as the geothermal water temperature, ambient temperature and direct normal irradiation on the power plant performances are analyzed. A code is established using Engineering Equation Solver software (EES) to perform the required calculations. Obtained results show that the hybrid solar-geothermal power plant with a heat recovery system is the most suitable configuration design giving a better overall energy efficiency of 15.77 and13.11% and a maximum net power of 1089 and 1882 kW in winter and summer, respectively. However, in the summer season, using a heat recovery system can valuable only when the water temperature is higher than 66°C. For air-cooled condenser, the suitable condensing pressure is 1 bar in winter and 1.9 bars in summer. [ABSTRACT FROM AUTHOR]

Air-light hydrocarbon mixing gas is a new type of fuel with great potential, and its key component is n-pentane. In this study, a reduced n-pentane mechanism with NO X is developed for combustion simulation at atmospheric pressure, including 81 species and 348 elementary reactions. First, the dominant species and reactions for n-pentane combustion are recognized by the reaction pathway analysis based on the detailed mechanism. Then, a novel multistep reduction strategy with intersection thought is proposed to reduce the detailed mechanism of n-pentane. Ignition delay time and laminar flame speed are separately selected as the target parameters for validation. The two reduced mechanisms are developed by using the directed relation graphs (DRG) method, the directed relation graphs with error propagation (DRGEP) method, and the full species sensitivity analysis (FSSA) method. Species in the intersection mechanism of the above two mechanisms obtained with multistep reduction are treated as important species. Sensitivity analysis (SA) is further performed to remove the uncertain species, combined with the result of reaction pathway analysis, a reduced n-pentane mechanism including 77 species and 336 reactions is obtained. On this basis, a reduced NO X mechanism (4 species and 12 reactions) is incorporated. Then, the key kinetic parameters of the mechanism are optimized and adjusted according to the results of brute force sensitivity analysis. Finally, the proposed mechanism is validated by using the related data of ignition delay times, laminar flame speeds, premixed flame species profiles, and jet-stirred reactor (JSR) species profiles. The results indicate that the proposed mechanism shows good model performance. This study can provide significant assistance for subsequent research on air-light hydrocarbon mixing gas. • A novel multistep reduction strategy with intersection thought is proposed. • The brute force sensitivity analysis is used to optimize the reduced mechanism. • The proposed compact mechanism covers important details of low- and high-temperature reactions. • The proposed mechanism predicts combustion characteristics and captures species evolution trends with sufficient accuracy. [ABSTRACT FROM AUTHOR]

An experimental study was undertaken to assess the heat-transfer coefficient (HTC) of graphene nanoplatelets-pentane nanofluid inside a gravity-assisted heat pipe (HP). Influence of various parameters comprising heat flux, mass fraction of the nanoparticles, installation angle and filling ratio (FR) of the working fluid on the HTC of the HP was investigated. Results showed that the HTC of the HP was strongly improved due to the presence of the graphene nanoplatelets. Also, by enhancing the heat flux, the HTC of the HP was improved. Two trade-off behaviors were identified. The first trade-off belonged to the available space in the evaporator and the heat-transfer coefficient of the system. Another trade-off was identified between the installation angle and the residence time of the working fluid inside the condenser unit. The installation angle and the FR of the HP were identified in which the HTC of the HP was the highest. The value of installation angle and filling ratio were 65° and 0.55, respectively. Likewise, the highest HTC was obtained at the largest mass fraction of the graphene nanoplatelets which was at wt. % = 0.3. The improvement in the HTC of the HP was ascribed to the Brownian motion and thermophoresis effects of the graphene nanoplatelets. [ABSTRACT FROM AUTHOR]

BACKGROUND Over the past few decades, tri‐n‐butyl phosphate (TBP) has been a widely used and irreplaceable extractant that can extract a variety of heavy metal ions and inorganic acids. The conventional process of tri‐n‐butyl phosphate synthesis has the problem of low yield. The in situ vapor stripping method was developed to intensify the tri‐n‐butyl phosphate synthesis reaction. RESULTS: In this work, the coupling process of in situ vapor stripping and reaction was proposed for the first time in the process of synthesis of TBP. It was found that the reaction of high concentration hydrogen chloride and 1‐butanol would produce water, which resulted in increasing the possibility of side reactions, especially when the temperature was higher than 55 °C. In the lower temperature range, n‐pentane was selected as the stripping medium, which effectively removed hydrogen chloride from the reaction system by in situ vapor stripping. The FT‐IR analysis confirmed that TBP can be synthesized successfully by the vapor stripping process. In addition, the effects of n‐pentane volume, temperature and stripping time on the yield of TBP and the amount of hydrogen chloride stripped were investigated. By applying the optimum reaction conditions, the yield of TBP was increased to 94%, larger than that of the current industrial process whose yield is only 80%. CONCLUSION: The in situ vapor stripping process is demonstrated to be an effective method for intensification of the esterification process in TBP synthesis. It can be used for other reactions which generate volatile gases as the byproduct. © 2018 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

The physicochemical properties of alumina–platinum catalysts with supports prepared by mixing aluminum and zirconium hydroxides have been studied. The chemisorption and nonoxidative conversion of methane in the presence of the above systems have been investigated. The effect of the zirconium content on the activity and selectivity of the conversion of chemisorbed CH4 and n-C5H12 into aromatic hydrocarbons has been established. [ABSTRACT FROM AUTHOR]

Fuel development for solvent deasphalting (SDA), by means of which it is possible to obtain high yields of deasphalted oil (DAO) with acceptable quality for subsequent refining in catalytic cracking processes and hydrocracking in particular, is nowadays becoming increasingly important. In this paper, an experimental study of the SDA of tar (vacuum residue) with n-pentane at various extraction temperatures and pressures was undertaken, and this made it possible to determine the effect of the phase state of the solvent on the yield, composition, and properties of the separation products,. It was shown that transfer of pentane from the liquid phase state to the region of a subcritical and then supercritical fluid (SCF) increases the solubility of the tar components and the yield of the DAO for fixed values of the solvent density. Despite some decrease in the quality of the DAO in the case of supercritical extraction at temperatures close to the critical temperature of the solvent (220°C), the phase state of the pentane has little effect on the metal content of the products, the carbon residue content of the DAO, and the softening point of the asphalt for the given yields. [ABSTRACT FROM AUTHOR]

PVTx-properties of the HO - n-CH and HO - n-CH mixtures are measured in the temperature range 303-680 K at pressures up to 60 MPa. The measurements were carried out along 265 liquid and vapor isochors in a density range of 63-713 kg/m. The measurements were performed for 15 concentrations between 0.110 and 0.987 mole fractions of HO for the CH mixtures and for 11 concentrations between 0.166 and 0.977 mole fractions of HO for the CH mixtures. The temperatures and pressures on the three-phase and two-phase boundary curves were obtained for the mixtures from isochors using the kink or inflection method. The data for the critical parameters of the upper and lower branches of the critical curves were obtained from the boundary curves by the method of rectilinear diameter. The measured three-phase data were used to estimate the value of the upper final critical point. [ABSTRACT FROM AUTHOR]

Hydrous and anhydrous isothermal experiments on n-pentane and n-octadecane were conducted at 300–375℃ for durations up to 1094 h to evaluate the cracking and hydrolysis of hydrocarbons, using fused silica capillary capsules as micro-reactors. The chemical compositions of the gaseous products during cracking of n-octadecane at 350 and 375℃ were methane, ethane, propane, and n-butane. The aqueous product in the hydrolysis of n-pentane and n-octadecane at 300–375℃ was alcohol. Alkenes and hydrogen were not detected throughout all the isothermal experiments. Results showed that the gaseous yields were characterized by higher contents of wet gas than those in natural gas accumulations. Mechanisms regulating the enrichment of methane in reservoirs should be further studied. The hydrolysis and oxidation of hydrocarbon were relatively limited in the absence of iron-bearing mineral buffers, suggesting that hydrocarbons might be more stable in iron-poor reservoirs (e.g. carbonate and quartz arenite) than in iron-bearing-mineral-rich ones (e.g. mudstone and arkose) under deep burial conditions. The absence of hydrogen was ascribed to its high diffusion rate in fused silica than in gold tube; any hydrogen produced in the reaction tends to diffuse out of the fused silica capsule with no or limited hydrogen accumulation, similar to those in geological environment. The diffusion of hydrogen should be considered during calculating the volume and pressure changes in the thermal cracking of oil to gas in reservoirs, because the loss of hydrogen would result in a decrease in the conversion rate of oil to gas. [ABSTRACT FROM AUTHOR]

The state and size of the metal on the surface of aluminum oxide and the acidic properties of the support depending on the concentration of supported platinum were studied in this work. The effect of the Pt content of the alumina-platinum catalyst on the activation (chemisorption) of methane was investigated, and the composition of hydrocarbon fragments formed in this case was calculated. The sample most active in a reaction of the joint conversion of methane with n-pentane, which was performed for the production of aromatic hydrocarbons under nonoxidizing conditions, was established. The effect of the temperature of n-pentane supply to the reaction atmosphere was studied for the 0.6%Pt/Al2O3 catalyst. The degree of enrichment of the resulting aromatic hydrocarbons and the quantity of incorporated methane activated on the catalyst surface were determined with the use of isotope mass spectrometry. [ABSTRACT FROM AUTHOR]

The utilization of a microcontroller board, optimized for the simultaneous data logging of chromatographic information, the oven temperature, and remote transfer to a personal computer, is investigated, with the goal to extend the capabilities of a gas chromatograph (Shimadzu GC-14A) which does not include a built-in data logging module. An initial comparison of the chromatographic peaks obtained from solute injections, collected both by a dedicated analog-to-digital expansion card and the microcontroller board, demonstrated the latter’s ability to perform accurate analog signal digitization. Afterward, the evaporation of three organic liquids (methanol, acetone, andn-pentane) was studied by reversed-flow inverse gas chromatography. From the temperature variation of the experimentally determined rates, the respective thermodynamic functions of enthalpy and entropy changes of acetone and methanol evaporation were determined. The small deviations from the theoretical values indicate the reliability of the proposed methodology. More importantly, it was made apparent that by utilizing automatic data logging instead of the carrier gas flow reversal procedure, the monitoring of rapid physicochemical phenomena was performed with better accuracy, while the duration of the experiments was decreased with the reduced consumption of gas chromatographic consumables. [ABSTRACT FROM PUBLISHER]

At the present work, foaming process (bubbles nucleation and growth) of Polystyrene (PS)/n-pentane batch foaming system was studied experimentally and theoretically. Synthesized PS was characterized by rheological measurements and the foaming dynamics was studied using a designed in-situ observation apparatus. The saturation time at the lowest mass diffusivity conditions was determined to ensure that all experiments would be performed at saturation state. Dissolved content and Henry's constant of n-pentane in PS at foaming conditions were also determined. The effects of temperature and sorption pressure as operation parameters on the foaming dynamics of PS/n-pentane system were investigated and it was found that temperature had a dramatic effect on the foaming dynamics and other parameters such solubility, diffusivity and melt strength were affected by temperature. Moreover, the bubble growth behavior of PS/n-pentane system was simulated and it was compared to the experimental results. To calculate concentration profile in the shell, mass diffusion equations were solved by implicit method with considering gas escape from the outer layer of the viscoelastic shell around the bubble. Furthermore the effect of mass diffusivity and viscosity on the bubble growth behavior was examined simultaneously and it was emphasized that the bubble growth behavior was a mass diffusion controlled phenomenon. [ABSTRACT FROM AUTHOR]

In this work, styrene-methyl methacrylate copolymer particles were synthesized by suspension polymerization process with different copolymer compositions. A system was designed to measure the solubility and diffusivity of n-pentane in the synthesized copolymers. The designed system consisted of the self-sealing cell equipped to the pressure and temperature controllers. The synthesized copolymer particles were impregnated by n-pentane and their expansion were recorded visually. Furthermore, the solubility and diffusivity of n-pentane in copolymer particles were measured by the same apparatus. The effect of different foaming conditions on the solubility and diffusivity of n-pentane in the samples were examined. It was concluded that the sorption pressure and temperature have contradictory effects on the solubility and diffusivity of n-pentane in styrene-methyl methacrylate copolymers at different sorption pressures. It was concluded that with methyl methacrylate content increment in copolymer, the diffusivity and dissolved n-pentane content in copolymer were reduced. [ABSTRACT FROM AUTHOR]

n-Paraffins are extensively used in the fabrication of detergents. These linear hydrocarbons can be selectively separated by adsorption from petroleum fractions using the appropriate adsorbent. Equilibrium and kinetic parameters are necessary to develop and design an adsorption process. These parameters are available in the literature for light paraffins in vapour phase, however there is scarce information concerning high molecular weight paraffins in liquid phase. The aim of this work is to study the equilibrium and kinetics of high molecular weight n-paraffins such as C10, C14 and C18 on a calcium LTA molecular sieve (5 A zeolite) in liquid phase. Pentane has also been analysed as it is mainly used as desorbent in the cyclic simulated moving bed (SMB) adsorption-desorption process of paraffins. A theoretical model has been developed to describe the column adsorption dynamics of the studied systems. The model has been included in a SMB simulation program, and the model prediction has been compared with the separation performance data reported for a commercial SMB unit that separates normal paraffins from a hydrotreated kerosene fraction. [ABSTRACT FROM AUTHOR]

Pt-promoted S2O82-/ZrO2-Al2O3 (SZA) catalysts were successfully prepared by the microemulsion (Pt-SZA-M) and impregnation (Pt-SZA-I) methods. The effects of the preparation parameters (surfactant-to-oil ratio, surfactant-to-cosurfactant ratio, types of cosurfactant and oil phase, etc.) on the catalytic activity of Pt-SZA-M catalysts in the isomerisation of n-pentane were investigated. The results showed that the optimal catalyst preparation conditions were: a cetyltrimethylammonium bromide (CTAB)/n-butanol mass ratio of 4:6, a (CTAB + n-butanol)/cyclohexane mass ratio of 3:7, a content of H2PtCl6 solution in microemulsion of 3.6 wt% and a N2H5OH/H2PtCl6 molar ratio of 25:1. A comparison of the isopentane yield for Pt-SZA-M with that for Pt-SZA-I was also performed. The results showed that the microemulsion method led to smaller and more uniform Pt particles (4.5 nm) on the SZA. In comparison with Pt-SZA-I, the isopentane yield for Pt-SZA-M was increased by 13.5% at 180 °C, showing the catalytic performance of Pt-SZA-M at lower temperature was improved significantly. At a reaction temperature of 230 °C, a pressure of 2.0 MPa, a hydrogen/n-pentane molar ratio of 4:1 and a weight hourly space velocity of 1.0 h-1, the yield of isopentane for Pt-SZA-M reached 60.8%. [ABSTRACT FROM AUTHOR]

In this work, styrene/methyl methacrylate (St/MMA) copolymer particles were synthesized by suspension polymerization process with different copolymer compositions to study the visual batch foaming dynamics. The visualization system consisted of the self-sealing observation cell equipped to the pressure and temperature controller. The synthesized copolymer particles were impregnated by n-pentane, followed by recording of particle expansion. The cell structure of foams was studied by scanning electron microscopy. The effect of different foaming conditions on the expansion behavior of copolymers was examined. It was concluded that sorption pressure and temperature have contradictory effects on the foaming ratio of the synthesized copolymers at lower and higher sorption pressures, and the results were confirmed with the foams’ cell structure. Furthermore, it was shown that, at different temperatures and pressures, the expansion behavior change dramatically with increasing of MMA content in the copolymer. [ABSTRACT FROM AUTHOR]

Methane adsorption on the Pt-H/AlO and Pt/AlO catalysts begins at Т = 475°C and is accompanied by the appearance of hydrogen in the reaction medium. At a higher temperature is raised to 550°C, the amount of adsorbed hydrogen increases to 1.1 and 0.8 mol/(mol Pt), respectively. According to the calculated degree of methane dehydrogenation on platinum sites at Т = 550°C, the Н/C ratio is 1.3 (at/at) for the Pt-H/AlO catalyst and 1.5 (at/at) for the Pt/AlO catalyst. The introduction of n-pentane into the reaction medium increases the yield of aromatic hydrocarbons (benzene and toluene) by a factor of 8.8 over the arene yield observed in individual n-pentane conversion. A mass spectrometric analysis of the arenes obtained with the Pt/AlO catalyst has demonstrated that 37.5% of the adsorbed methane is involved in the methane- n-pentane coaromatization yielding benzene and toluene. [ABSTRACT FROM AUTHOR]

Fe-Zn-doped SO/ZrO-AlO (SZA) catalysts were synthesized and characterized by using X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) analysis, Fourier transform infrared (FT-IR) measurements, hydrogen temperature-programmed reduction (H-TPR), and pyridine infrared (Py-IR) measurements. The effects of Fe and Zn on the structure and isomerization performance of SZA were studied using n-pentane as a probe reaction. Results showed that all of the samples show the pure peaks of tetragonal ZrO. The addition of Zn can improve the redox performance of the catalysts, while Fe can lead to a better dispersion of sulfate ions on the surface of the catalysts. As a result, an improvement in the redox performance of the Zn-Fe-SZA catalyst was observed. The Zn or Fe can increase mainly Lewis acidity of the SZA, and the total acidity of samples decrease in the following order: Zn-Fe-SZA > Zn-SZA > Fe-SZA > SZA. The Fe-Zn-SZA catalyst exhibits the best catalytic activity for n-pentane isomerization. The isopentane yield of the Zn-Fe-SZA catalyst reaches 67.2 % at 443 K, which is an increase of 44.2 % when compared with that found for SZA at its optimum temperature of 573 K. [ABSTRACT FROM AUTHOR]

pVT-properties of the binary mixture 0.973 water + 0.027 n-pentane (mole fraction composition) have been studied in the temperature interval from 310 to 675 K and pressure range up to 60 MPa at a wide range of densities along 10 different isochors using a high-pressure constant-volume piesometer. Lines of phase equilibria and critical points of the mixture have been determined. The investigation involves dissolution of the hydrocarbon in water (L-L transition) and the transition of the hydrocarbon-water solution into the gas phase, including critical and supercritical regions. [ABSTRACT FROM AUTHOR]

New, wide-range reference equations for the thermal conductivity of cyclopentane, iso-pentane, and n-pentane are presented. The equations are based in part upon a body of experimental data that has been critically assessed for internal consistency and for agreement with theory whenever possible. In the case of the dilute-gas thermal conductivity, a theoretically based correlation was adopted in order to extend the temperature range of the experimental data. In the critical region, the enhancement of the thermal conductivity is well represented by theoretically based equations containing just one adjustable parameter, estimated by a predictive scheme. The thermal-conductivity equations behave in a physically reasonable manner over a wide range of conditions that correspond to the range of validity of the most accurate equations of state for each fluid. The estimated uncertainties of the correlations are dependent on the availability of accurate experimental data for validation, and are different for each fluid, varying from 1% (at the 95% confidence level) for the liquid phase of iso-pentane over the temperature range 307 K < T < 355 K at pressures up to 400 MPa (where high-accuracy data are available) to a more typical 4% for the liquid phase of cyclopentane over the temperature range 218 K < T < 240 K at pressures to 250 MPa. Estimated uncertainties in the gas phase are typically on the order of 3%-5%. For all three fluids, uncertainties in the critical region are much larger, since the thermal conductivity approaches infinity at the critical point and is very sensitive to small changes in density. [ABSTRACT FROM AUTHOR]

The pVT-properties of water + n-pentane and water + n-hexane mixtures in temperature intervals from 305 to 542 K and pressures up to 15 MPa were measured in a constant-volume piezometer. The line of phase equilibrium hydrocarbon-vapor with water and their critical parameters were determined. Critical temperatures and pressures are constant and close to 0.9 mol fraction of water, remaining the same as for the upper critical end-point, while the densities increase. All critical parameters decrease above 0.93 mol fraction of water. The common three-phase lines for measured systems are presented. [ABSTRACT FROM AUTHOR]

The thermal properties of binary n-pentane-water (1: 4, wt.) system, as well as hydrocarbon liquid-vapor and aqueous liquid-vapor phase equilibria, were studied in the temperature range between 303 and 674 K under pressures (up to 60 MPa) along nine different isochores. The phase-equilibrium lines and critical points for the system were obtained, and the phase diagrams are described. [ABSTRACT FROM AUTHOR]

The paper presents an experiment on superheated n-pentane boiling-up in a glass capillary at atmospheric pressure using a high-speed video. The video shooting was first performed in two mutually perpendicular directions. Two obtained images allowed concluding, on which side of the vessel wall the bubble forms, and whether we observe one bubble with an image, deformed due to the curvature of the capillary, or two bubbles located nearby. These data prove the surface (heterogeneous) character of boiling-up. [ABSTRACT FROM AUTHOR]

The liquid adsorption separation ofn-paraffins in naphtha withn-pentane as the desorbent was investigated and the subsequent recycle ofn-pentane was simulated by Aspen Plus. The optimal operation conditions for both the adsorption and desorption processes were studied. Thenn-pentane was recycled by simulated rectification; the raffinate bottom oil rich in non-normal hydrocarbons and the desorption bottom oil rich in normal hydrocarbons were obtained. As compared to the naphtha before the adsorption-recycle process, the ethylene yield would rise by 15.76% by employing the desorption bottom oil as the feed for the ethylene cracking process and the octane number of the raffinate bottom oil would rise by 20 units. [ABSTRACT FROM PUBLISHER]

In constant volume piezometer, the experimental data on P,V,T,x -- properties of binary stratifying n-Pentane - water system with the concentrations: 0.11; 0.143; 0.174; 0.203; 0.209 and 0.214 mass % of H2O are obtained within the density ranges from 63 to 611 kg/m³ The phase equilibrium curves of liquid -- liquid and liquid -- vapor are determined. An azeotrope state is assumed to be defined by a crossing point of these lines. An azeotrope line, finishing in the upper end critical point, is plotted. [ABSTRACT FROM AUTHOR]

Alkyl chains are common structural units, for example in lipids, and their 1H NMR spectral parameters offer valuable information about their conformational behavior in solvent environment. Even the spectra of short n-alkanes are complex, which is obviously a reason why their accurate spectral analyses have not been reported before. The present study reports the quantum mechanical analysis of 1H NMR spectra of n-butane, n-pentane, n-hexane, and n-heptane. The spectral parameters were used to characterize the conformational behavior of n-alkanes. The temperature dependence analysis of coupling constants suggests that the enthalpy difference between the gauche ( g) and trans ( t) conformations (Δ Hg) of n-butane in chloroform is 2.55-2.85 kJ mol−1. The difference between the trans-gauche ( tg) and all-trans ( tt) conformers of n-pentane (Δ Htg) seems to be 0.1-0.2 kJ mol−1 higher. The coupling constant information shows that the tn conformations become more favored with longer chains, although not only for energetic reasons but also partly because the g+g- arrangements become sterically unfavorable, which decreases the number of favorable gn-type conformations. The analysis of the 1H NMR spectra of n-pentane and n-hexane in solvents representing different chemical environments indicates that polar and spherical dimethyl sulfoxide favors clearly the g conformations, whereas n-hexane- d14 favors slightly the extended tn conformation. In addition to the intrinsic scientific importance for NMR spectral parameter prediction and molecular modeling in solution, the results provide some insights to behavior of hydrocarbon chains and their spectra in different chemical environments. Copyright © 2012 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

In this study, we synthesized styrene–methyl methacrylate copolymer particles by suspension polymerization process to study the foaming dynamics via visual batch foaming apparatus. The weight ratio of styrene–methyl methacrylate was 53–47. The foaming system consisted of a self-sealing observation cell equipped with two glass windows and a stereo microscope attached with a high-speed digital camera as well as a pressure and temperature controller. The required pentane pressure was supplied by heating a small pentane flask. The synthesized copolymer particles impregnated by pentane and then the foaming dynamics were recorded after a rapid pressure release. The effect of different foaming conditions, such as temperature, impregnation time, and impregnation pressure on the expansion ratio of styrene–methyl methacrylate copolymer was investigated. It was concluded that impregnation pressure, time, and temperature have different effects on the foaming ratio at impregnation pressures lower and higher than 4 bar. [ABSTRACT FROM PUBLISHER]

The impact of fractional wettability on the production characteristics of a VAPEX process at the macroscale was investigated. Conventional VAPEX experiments were conducted in a 220 Darcy random packing of glass beads in a rectangular physical model and n-pentane was used to recover the Cold Lake bitumen from the oil-saturated model in the absence of connate water. The composition of oil-wet beads in the packed bed was altered from completely water-wet beads to completely oil-wet beads at different proportions of oil-wet beads mixed with water-wet beads. A substantial increase (about 40%) in the production rate of live oil was observed during the VAPEX process when the wettability of the porous packing was entirely oil-wet beads. A critical oil-wet fraction of 0.66 was found for the heterogeneous packing of water-wet and oil-wet beads of similar size distribution. Above this critical composition, the live oil production rate was not affected by further increase in the proportion of the oil-wet beads. It is believed that above this critical composition of the oil-wet beads, the crevice flow process is dominated by the continuity of higher conductivity live oil films between particles through the oil-wet regions. Below this critical composition, the live oil production rate increased linearly with the fraction of the oil-wet beads in the packing. The oil-wet regions favor the live oil drainage compared to that of the water-wet regions as they enhance the rate of imbibition of the live oil from the oil-filled pores to the vacated pores near the nominal VAPEX interface. These two factors enhance the live oil production rate during the VAPEX process. The solvent content of the live oil, the solvent-to-oil ratio (SOR), and the residual oil saturation did not correlate strongly with the proportion of the oil-wet beads in the packing. The average solvent content of the live oil and the residual oil saturation were measured to be 48% by weight and 7% by volume respectively. [ABSTRACT FROM AUTHOR]

The partition coefficient between volatile organic compounds (VOCs) and biomass is one of the most representative parameters in hydrophobic VOCs biofiltration. In this study, the n-pentane/dry-biomass partition coefficient (KDP/B) was determined in microcosms for the filamentous fungus Fusarium solani, it was grown in four packing materials (compost, peat, perlite and vermiculite) at different temperatures (15 °C, 25 °C and 35 °C). The results show that the n-pentane/wet-biomass partition coefficients (KWP/B) for all experiments in organic packing material were on average 160-fold lower (0.21 ± 0.09) than those in water (33.2 ± 9.4), while for inorganic packing material on average 700-fold lower (0.05 ± 0.04). On the other hand, it was observed that the KWP/B for the fungus grown in an inorganic packing material was on average 4-fold lower than when grown in organic packing material. In conclusion, the use of inorganic packing material increases the solubility (lower KWP/B) of n-pentane, increasing the elimination capacity in fungal biofilter. [ABSTRACT FROM AUTHOR]

The surface tension of (n-hexadecane+n-heptane), (n-hexadecane+n-pentane) and (n-hexadecane+n-heptane+n-pentane) mixtures were measured at 91.3 kPa and the 293.15-323.15 K temperature range by the maximum bubble pressure method. The surface tension of pure n-hexadecane was measured at 91.3 kPa and the 303.15-343.15 K temperature range. The measured surface tension data of pure n-hexadecane was correlated by SPTM3 model, which was obtained from coupling scaled particle theory (SPT) and MMM equation of state. For the extension of the SPTM3 model to mixture calculations, the commonly used mixing rules for the cubic equations of state were applied. The comparisons between the obtained surface tension data and those calculated by the SPTM3 model indicate that the data can be described with deviations less than 1.56%. Therefore, the SPTM3 model is applicable for surface tension calculations of the studied mixtures. [ABSTRACT FROM AUTHOR]

Foaming of blend systems is a promising approach to develop cellular materials with a set of desired properties. However, foaming of blend systems is not only a chance but also a challenge, as different polymers have to be foamed at the same foaming conditions. The best conditions during foaming are individual to each polymer and influence the obtained cellular structure. In immiscible polymer blends like poly(2,6-dimethyl-1,4-phenylene ether) (PPE) and poly(styrene-co-acrylonitrile) (SAN) the differences in glass-transition temperature (Tg) and viscosity are vast and can inhibit the foaming of the blend system. In order to minimize the above-mentioned difference in Tg and viscosity, one approach is to choose a blowing agent, which shows a selective solubility in one polymer phase, working as a selective plasticizer. The aim of the present study is to evaluate systematically the foaming behavior of immiscible PPE/SAN blend systems using ethanol and n-pentane as blowing agents. Mass uptake of ethanol and n-pentane in the PPE/SAN-blends as function of the blend composition is measured, offering a selective solubility of ethanol in SAN, while n-pentane shows a high affinity to PPE. The plasticizing effect on the blend phases PPE and SAN is theoretically estimated using the Chow-equation and the WLF-equation. After foaming the blowing agent saturated blend samples in an oil-bath at different temperatures, the density reduction and the cellular structures are analyzed and correlated to the blend morphology, the blowing agent solubility in the blend phase, the rheological properties and the glass transition temperature of the nonsaturated and saturated blend phases. [ABSTRACT FROM AUTHOR]

Pt/H-ZSM-5 and Pt/H-MOR catalysts with different Pt contents were prepared via impregnation using H2PtCl6 · 6H2O or via exchange using Pt(NH3)4Cl2, calcination in air at 530°C and reduction in H2 at 500°C. The prepared catalysts were tested for n-pentane hydroisomerization and hydrocracking via bifunctionality at 250-500°C using a micro-catalytic pulse reactor. It is found that the dispersion of Pt-exchanged zeolites is higher than the corresponding Pt-impregnated zeolites at all Pt contents. It is also found that the dispersion of Pt/H-ZSM-5 catalysts either exchanged or impregnated are higher than the corresponding Pt/H-MOR catalysts. Temperature-programmed desorption (TPD) data showed that the impregnated catalysts possess a higher acid sites number than the exchanged catalysts; and that the Pt/H-ZSM-5 catalysts have a higher number of acid sites than do the Pt/H-MOR catalysts, whereas the latter catalysts possess higher strength of acid sites at all Pt contents. The hydroisomerization activities using Pt exchanged catalysts, supported either on H-ZSM-5 or H-MOR, are higher than the impregnated catalysts at almost all Pt contents. It is also concluded that the H-ZSM-5-supported catalysts, either exchanged or impregnated, are more active than the H-MOR supported ones. Hydrocracking is higher using all loaded H-MOR catalysts. [ABSTRACT FROM AUTHOR]

The quantum chemical calculations at the different levels of theory were performed with the target being to determine the vibration frequencies and to estimate the barriers to internal rotations of n-pentane molecules. In connection with the observed losses of CH3 and CH4 from the n-pentane in gas phase, the calculations at the B3LYP level of theory with the 6-31G(d) basis set were used to study the ground-state potential energy surface of the n-pentane. © 2008 Wiley Periodicals, Inc. Int J Quantum Chem, 2009 [ABSTRACT FROM AUTHOR]

Skeletal isomerization of n-pentane in the presence of hydrogen has been studied over Pt-promoted H3PW12O40 (TPA)/MCM-41 bifunctional catalyst. A series of solid acid catalysts with different loading amount of TPA and Pt were prepared and characterized by XRD, FT-IR and XPS. The optimal catalytic activity of Pt-TPA/MCM-41 was observed with 2% Pt and 30% TPA. According to the cracked products distribution, this is typical of a monomolecular bifunctional metal-acid mechanism. Further, catalysts with different combination of noble metals (Pt, Pd and Ru), heteropoly acids (HPAs) (TPA, tungstosilicic acid (TSA), and molybdophosphoric acid (MPA)) and supports (MCM-41, SBA-1 and SiO2) were also synthesized and their catalytic performances were compared. [ABSTRACT FROM AUTHOR]

Hydroisomerization of n-pentane over platinum promoted acids zeolites was studied. The effect of structure and acidity of the support was investigated at atmospheric pressure between 250 and 400 °C. Pt/HDBEA catalyst showed the best performance at 300 °C with high activity and selectivity to isopentane, due to its structure and a proper balance between acid and metallic sites. This catalyst has a high catalytic stability and regeneration under air flow after deactivation by coking, restores its activity and selectivity. [ABSTRACT FROM AUTHOR]

The transient hot-wire technique is widely used for absolute measurements of the thermal conductivity of fluids. Refinement of this method has resulted in a capability for accurate and simultaneous measurement of both thermal conductivity and thermal diffusivity together with a determination of the specific heat. However, these measurements, especially those for the thermal diffusivity, may be significantly influenced by fluid radiation. The present work investigates the effect of fluid radiation on the measurements of the thermal conductivity of propane. Recently developed corrections have been used to examine this assumption and rectify the influence of even weak fluid radiation. Measurements at 372 K with a hot-wire instrument demonstrate the presence of radiation effects in both the liquid and vapor phase. The influence is much more pronounced in liquid propane at 15.5 MPa than in the vapor phase at 881.5 kPa. The technique employed to obtain radiation-free thermal conductivity measurements is described. [ABSTRACT FROM AUTHOR]

The transient hot-wire technique is widely used for absolute measurements of the thermal conductivity and thermal diffusivity of fluids. It is well established that fluid radiation effects significantly influence these measurements, especially those for the thermal diffusivity. Corrections for radiation effects are based on the models developed and deviations of the measured data from the ideal line source model. In this paper, the effect of fluid radiation on the measurements of the thermal conductivity of n-pentane is presented. For comparison, the influence of thermal radiation effect on measurement of transparent fluids, such as argon is also shown. The difference between the influence of natural convection and thermal radiation is also demonstrated. [ABSTRACT FROM AUTHOR]