Showing papers by "China University of Petroleum published in 2007"
TL;DR: In this article, force-field-based molecular dynamics simulations are performed to study the interaction between polymers and single-walled nanotubes (SWNTs), which are considered promising reinforcement materials for the next generation of high-performance structural and multifunctional composites.
Abstract: Single-walled nanotubes (SWNTs), which have a unique electronic structure, nanoscale diameter, high curvature, and extra-large surface area, are considered promising reinforcement materials for the next generation of high-performance structural and multifunctional composites. In the present study, force-field-based molecular dynamics simulations are performed to study the interaction between polymers and SWNTs. The “wrapping” of nanotubes by polymer chains was computed. The influence of temperature, nanotube radius, and chirality on polymer adhesion was investigated. Furthermore, the “filling” of nanotubes by polymer chains was examined. The results show that the interaction between the SWNT and the polymer is strongly influenced by the specific monomer structure such as aromatic rings, which affect polymers' affinities for SWNTs significantly. The attractive interaction between the simulated polymers and the SWNTs monotonically increases when the SWNT radius is increased. The temperature influence is neg...
176 citations
TL;DR: In this paper, Ru catalysts supported on different carbons were used for catalytic ammonia decomposition, and the influences of the porous and graphitic structures of carbon supports on the activities of the catalysts were examined.
Abstract: Catalytic ammonia decomposition has been of increasing interests as a means of supplying pure hydrogen for fuel cells. In this study, Ru catalysts supported on different carbons were used for catalytic ammonia decomposition. The influences of the porous and graphitic structures of carbon supports on the activities of the catalysts were examined. The catalytic activity over supported Ru catalysts is ranked as Ru/GC (graphitic carbon) > Ru/CNTs (carbon nanotube) > Ru/CB-S (carbon black) > Ru/CB-C > Ru/CMK-3 approximate to Ru/AC. The samples are characterized by XRD, N-2 adsorption, Raman spectra and H-2 chemisorption. Ru particles are highly dispersed on carbon supports. The optimum range of Ru particle sizes is around 3-4 nm. On the support side, the graphitic structure of the carbons is critical to the activity of the supported Ru catalyst, while the surface area of carbons is less important. (c) 2007 Elsevier B.V. All rights reserved.
176 citations
TL;DR: In this paper, a facile surfactant-assisted hydrothermal method was used to construct as-obtained CeO2 spherical crystallites with promising electrochemical properties that may be used as an anode material in lithium ion batteries.
Abstract: CeO2 spherical crystallites aggregated by small CeO2 nanoparticles in the diameter range of 5−10 nm were successfully fabricated through a facile surfactant-assisted hydrothermal method. PVP (poly(vinylpyrrolidone)) was applied as surfactant to facilitate the oriented aggregation of small CeO2 nanoparticles into spherical crystallites. The size of as-obtained CeO2 spherical crystallites could be deliberately controlled in the range 100−800 nm by varying synthetic parameters such as the molar ratio of PVP (repeating units) to Ce(NO3)3·6H2O and the concentration of Ce(NO3)3·6H2O solution. The formation mechanism was briefly discussed and the electrochemical properties of as-synthesized CeO2 spherical crystallites were studied by galvanostatic methods. The electrochemical test results show that the as-obtained CeO2 spherical crystallites have promising electrochemical properties that may enable them to be applied as an anode material in lithium ion batteries.
176 citations
01 Jun 2007
TL;DR: N(2) adsorption tests show that the synthesized OMCs possess abundant mesopores and centralized mesopore distribution, and the most probable pore diameter of O MCs was found to be vital to the adsorptive capacity and adsorptions rate of MB and NR.
Abstract: Ordered mesoporous carbons (OMCs) with varying pore size, and microporous carbon, CFY, were synthesized using ordered mesoporous silica SBA-15 and NaY zeolite as hard templates, respectively. N2 adsorption tests show that the synthesized OMCs possess abundant mesopores and centralized mesopore distribution. Methylene blue (MB) and neutral red (NR) were used as probe molecules to investigate their adsorption behaviors on OMCs and CFY. As evidenced by adsorption tests, the volume of mesopores of which the pore size is larger than 3.5 nm is a crucial factor for the adsorption capacity and adsorption rate of MB on OMCs. However, the most probable pore diameter of OMCs was found to be vital to the adsorption capacity and adsorption rate of NR. Theoretical studies show that the adsorption kinetics of MB and NR on OMCs can be well depicted by using pseudo-second-order kinetic model.
175 citations
TL;DR: It is proposed that future land-use policy should pay more attention to the crucial ecosystem functions of these forests (including tropical forest), and that it is necessary to balance the relationship between the livelihood of local farmers and environmental protection in order to maintain a healthy and stable ecosystem.
Abstract: Pingbian Miao Autonomous County is one of the poorest rural areas in China. Land-use changes, mainly driven by agricultural expansion and deforestation, may significantly impact ecosystem services and functions, but such effects are difficult to quantify. In the present study, Landsat image data were combined with the published coefficients about the world and China ecosystem to quantify land-use and ecosystem service changes in the mountainous area. A sensitivity analysis was employed to determine the effect of manipulating these coefficients on the estimated values. Our results show that during the past decades (from 1973 to 2004) forests and grasslands were converted into shrubland and cropland, respectively, resulting in a continuous decrease in ecosystem service (from 124.5 US$ × 106 in 1973 to 100.4 US$ × 106 in 2004). We found that the decrease of mixed forest in the study area was the largest contributor (i.e., 25.4 US$ × 106) to the decline of the ecosystem service. Therefore we propose that future land-use policy should pay more attention to the crucial ecosystem functions of these forests (including tropical forest), and that it is necessary to balance the relationship between the livelihood of local farmers and environmental protection in order to maintain a healthy and stable ecosystem.
166 citations
TL;DR: In this article, the authors established a faunal sequence of early Oligocene to early Pliocene age for mammalian fossils from the Qaidam Basin of the Tibetan Plateau.
142 citations
TL;DR: In this article, an effective way has been brought forward to reduce this passive effect of embedment on the fracture conductivity, which is significant for both theoretical study and field treatments.
139 citations
TL;DR: In this article, a simple three-dimensional model was used to predict the positions of secondary petroleum migration pathways in heterogeneous carrier beds in Bozhong sub-basin, Bohai Bay basin.
128 citations
TL;DR: In this paper, a hierarchical macro-meso-micro-porous structure was synthesized via in situ assembly of preformed zeolite Y nanoclusters on kaolin using cetyltrimethylammonium bromide as template under alkaline conditions.
125 citations
TL;DR: In this article, the effects of rare earth (RE) on the structure, acidity, and catalytic performance of HZSM-5 zeolite were investigated by means of FT-IR, UV-Vis, NH 3 -TPD, and IR spectroscopy of adsorbed pyridine.
121 citations
TL;DR: In this paper, an imidazoline derivative for API X65 steel in CO2-saturated 5% NaCl solution has been studied by using potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) measurements.
TL;DR: In this paper, the authors defined the definition and composition of the pressure drop over a tangential inlet, reverse flow cyclone, and derived a universal model to predict the cyclone pressure drop by summing each loss.
TL;DR: In this paper, a nano-nickel catalyst was used in methylcyclohexane-water-n-octanol-AEO9 micro-emulsion system, and used in the viscosity reduction process of Liaohe extra-heavy oil by aqua-thermolysis.
TL;DR: It was found that the convective heat transfer control model reported in the literature could be used to formulate the lateral film growth rate v(f) with the driving force DeltaT perfectly for all systems after introduction of the assumption that the thickness of hydrate films is inversely proportional to the drivingForce.
Abstract: The lateral film growth rate of CH4, C2H4, CO2, CH4 + C2H4, and CH4 + C3H8 hydrates in pure water were measured at four fixed temperatures of 273.4, 275.4, 277.4, and 279.4 K by means of suspending a single gas bubble in water. The results showed that the lateral growth rates of mixed-gas CH4 + C2H4 hydrate films were slower than that of pure gas (CH4 or C2H4) for the same driving force and that of mixed-gas CH4 + C3H8 hydrate film growth was the slowest. The dependence of the thickness of hydrate film on the driving force was investigated, and it was demonstrated that the thickness of hydrate film was inversely proportional to the driving force. It was found that the convective heat transfer control model reported in the literature could be used to formulate the lateral film growth rate v(f) with the driving force DeltaT perfectly for all systems after introduction of the assumption that the thickness of hydrate films is inversely proportional to the driving force DeltaT; i.e., v(f) = psiDeltaT(5/2) is correct and independent of the composition of gas and the type of hydrate. The thicknesses of different gas hydrate films were estimated, and it is demonstrated that the thicknesses of mixed-gas hydrate films were thicker than those of pure gases, which was qualitatively consistent with the experimental result.
TL;DR: In this article, a novel experimental method to study the hydrate formation kinetics on the gas/water interface was presented and, using this method, the two-dimensional growth kinetic data of hydrate film on the surface of quiescent methane gas bubble suspended in pure water, natural water and natural water added with different contents of SDS were measured and compared.
TL;DR: In this paper, the scale-up effect of hydrate formation in the form of hydrates in a quiescent reactor was investigated and a multi-deck cell-type vessel was devised as the internals of the reactor, where water was loaded in each cell instead of being loaded in the reactor directly and the hydrate formed in all cells of the vessel simultaneously.
TL;DR: In this article, a model of the effective electrical conductivity for carbon nanotube (CNT) composites is presented by incorporating the interface effect with an average field theory.
Abstract: A model of the effective electrical conductivity for carbon nanotube (CNT) composites is presented by incorporating the interface effect with an average field theory. The dependence of the effective electrical conductivity on CNT length, diameter, concentration, and interface properties has been taken care of simultaneously in our treatment so that the model can describe well the interface effect of CNT composites. Predictions from the model are in good agreement with the experimental values of the effective electrical conductivity of CNT composites which the classical models have not been able to explain.
TL;DR: In this paper, the effects of overpressure on different aspects of organic matter maturation have been examined in three basins using multiple parameters, and the observed phenomena suggest differential retardation of different organic matter reactions and different maturity parameters have been retarded by overpressure to different degrees.
Abstract: The effects of overpressure on different aspects of organic matter maturation have been examined in three basins using multiple parameters. Overpressure in the Yinggehai Basin has retarded kerogen maturation, hydrocarbon generation, and thermal cracking of long-chain normal hydrocarbons, as well as evolution of isoprenoid hydrocarbons. Overpressure in the Dongpu depression, Bohai Bay Basin, seems to have retarded the maturation of bulk kerogens reflected by Rock-Eval Tmax, the thermal cracking of long-chain normal hydrocarbons, and the evolution of isoprenoid hydrocarbons, but seems to have had no detectable effects on vitrinite reflectance. Overpressure in the Qiongdongnan Basin has had no detectable retardation effects on all aspects of organic matter maturation. The observed phenomena suggest differential retardation of organic matter maturation (that is, different organic matter maturation reactions and different maturity parameters have been retarded by overpressure to different degrees in the same overpressured system) and four hierarchies of overpressure retardation. Hierarchy I retardation is defined as the state where the overpressure has retarded all aspects of organic matter maturation and is proposed to have been caused by the combination of high formation pressure and excess pressure, a high-water/organic matter ratio, and strong retention of reaction products in an early-developed, strong, persistent overpressured system. Hierarchy II retardation refers to the case in which all aspects of organic matter maturation except the maturation of hydrogen-poor kerogens, especially vitrinite, have been retarded and seem to have been caused by early-developed, moderate to strong, persistent overpressure. Hierarchy III retardation refers to the situation where overpressure has retarded only the thermal cracking of liquid hydrocarbons, but has had no detectable effect on the maturation of both hydrogen-rich and hydrogen-poor kerogens, and is proposed to have been caused by moderate to strong, persistent overpressures that began to develop around peak oil generation. Hierarchy IV retardation is defined as the situation where overpressure has had no detectable retardation on all aspects of organic matter maturation and may have been caused by cases wherein the overpressure developed too late, the intensity of the overpressure was too low, the duration of the overpressure was too short, or overpressured fluids had been expelled frequently. Resulting from both the diversities of organic matter maturation reactions and the complexities of overpressure generation and development, the hierarchies of overpressure retardation in different basins may be quite different, and it is necessary to use multiple parameters to understand the evolution of the petroleum systems in overpressured basins.
TL;DR: In this paper, the two-stage riser catalytic cracking for maximizing propylene yield has the following characteristics: relative lower temperature with larger catalyst/oil ratio, stratified injections of various feedstocks, and proper contacting time between catalyst and oil vapor.
Abstract: The two-stage riser catalytic cracking for maximizing propylene yield has the following characteristics: relative lower temperature with larger catalyst/oil ratio, stratified injections of various feedstocks, and proper contacting time between catalyst and oil vapor. These characteristics can enhance catalytic cracking and minimize thermal cracking, which is very favorable for maximizing propylene yield and lowering dry gas. The experimental results showed that using the special catalyst LTC-2 the yield of propylene is up to 24.11% and the liquid yield approaches 82% when the first stage riser is fed Daqing AR with butenes and the second is fed the light gasoline and heavy oil from the first stage. The final gasoline containing only 26% olefins and nearly 50% aromatics is the desired high octane-number component. The diesel must be hydrogenated due to its higher density.
TL;DR: The Kashi anticline is a doubly plunging detachment fold located in the SW Tian Shan foreland as mentioned in this paper, and the structure and topography of the emergent fold support interpretations of fold growth in three stages: initial symmetric lateral growth both east and west to a total length of 30 km followed by, first, rapid and, then, slower eastward lengthening to 72 ± 10 km total length.
Abstract: Received 11 February 2006; revised 16 January 2007; accepted 2 February 2007; published 28 March 2007. [1] The Kashi anticline is a north vergent, asymmetric, doubly plunging detachment fold located in the SW Tian Shan foreland. We combine structural, magnetostratigraphic, and topographic data to define the fold’s lateral propagation, surface uplift, and concomitant exhumation. Two new magnetostratigraphic sections indicate that the fold began growing at � 1.4 Ma and by 1.07 Ma, deformation had propagated eastward � 13 km at an average rate of � 40 km/Myr. Subsequently, propagation rates increased at least twofold, until the fold reached >60 km in length by 0.8 ± 0.3 Ma. Since then, eastward fold propagation slowed to � 15 km/Myr, and the eastern 15–25% of the fold remains buried in the rapidly aggrading foreland. The structure and topography of the emergent fold support interpretations of fold growth in three stages: initial symmetric lateral growth both east and west to a total length of � 30 km followed by, first, rapid and, then, slower eastward lengthening to 72 ± 10 km total length. Shortening rates as high as 1.9� 0.2 +0.3 mm/yr characterize the western part of the fold but decrease toward the east. Significant dissection of the emergent fold does not occur until topographic relief is sufficient (� 200 m) to permit stripping of protective conglomerates from across the fold’s upper surface. As differential rock uplift continues following breaching of the conglomerate, � 75% of the rock raised above local base level is subsequently eroded at rates as high as 2.4 km/Myr. Despite extensive erosion, the modern fold topography mimics spatial patterns of both long-term shortening and variations in rock uplift.
TL;DR: In this paper, the composites of PET with monodisperse SiO2-PS core-shell structured particles were prepared with SiO 2 size from 380-nm to 35-nm.
TL;DR: In this paper, the authors used a mixture of a conventional aqueous medium, a two-liquid phase medium and a two liquid phase medium, respectively, to synthesize SAPO-11 molecular sieves.
Abstract: Silicoaluminophosphates SAPO-11 molecular sieves were synthesized from a conventional aqueous medium, a two-liquid phase medium and a HF medium, respectively, and were characterized by various methods such as XRD, SEM, pyridine-FT-IR, NH 3 -TPD, 29 Si MAS-NMR. The morphologies of the SAPO-11 molecular sieves obtained from the conventional aqueous medium and the two liquid-phase media exhibit pseudo-spherical aggregates ranging from 7 to 10 μm assembled from cubic plate microcrystallites, whereas the SAPO-11 molecular sieves synthesized from the HF medium exhibit hexagonal prismatic aggregates of about 1–3 μm length. The synthesis media used highly influenced the number and the strength of SAPO-11 acid sites. Compared to SAPO-11 obtained from conventional aqueous medium, SAPO-11 prepared from two-liquid phase media possessed a similar number of BrOnsted acid sites but a much larger number of Lewis acid sites, whereas the SAPO-11 synthesized from HF medium had a similar number of Lewis acid sites but a much lower number of BrOnsted acid sites. The 29 Si MAS-NMR spectra showed that the HF could change the manner of Si incorporation into the SAPO-11 framework. The hydroisomerization of n -hexadecane on Pt/SAPO-11 samples showed that Pt/SAPO-11 obtained from the two-liquid phase media had the largest yield of isomers. The conversion activity of n- hexadecane was dependent on the amount of BrOnsted acid of SAPO-11 molecular sieves, while its hydrocracking activity was related to the strong acid sites of SAPO-11.
TL;DR: In this article, a high-speed video camera with a microscopic lens and a Schlieren optical system were used to record the flame propagation process and to obtain the direct light emission photographs.
Abstract: To investigate the flame propagation through hybrid mixture of coal dust and methane in a combustion chamber, a high-speed video camera with a microscopic lens and a Schlieren optical system were used to record the flame propagation process and to obtain the direct light emission photographs. Flame temperature was detected by a fine thermocouple. The suspended coal dust in the mixture of methane and air was ignited by an electric spark. The flame propagation speeds and maximum flame temperatures of the mixture were analyzed. The results show that the co-presence of coal dust and methane improves the flame propagation speed and maximum flame temperature notably, which become much higher than that of the single-coal dust flame. The flame front temperature varies with the coal dust concentration.
TL;DR: In this paper, a new deep desulfurization process for gasoline was obtained by means of electrochemical catalytic oxidation with an electrochemical fluidized-bed reactor on particle group anode.
TL;DR: In this article, the photocatalytic activity of single-and co-doping TiO2 nanoparticles with Fe3+ and Ho3+ ions was investigated by X-ray diffraction (XRD) and UV-vis absorption spectra.
TL;DR: A hydrothermal synthesis method for ZSM-5 preparation was investigated by using expanded perlite (or kaolin) as the only alumina source in this paper, which showed a better catalytic activity in the FCC naphtha aromatization reaction compared with a ordinary method.
TL;DR: The results of repeated use found that ozonation could efficiently regenerate ACF in situ in the reactor, which was considered easy to handle without the costly ex situ regeneration of the industrial treatment process.
TL;DR: In this paper, it was found that the as-synthesized CMK-3 carbon is not a good carbon catalyst support due to its amorphous structure resulting in the poor electron conductivity.
TL;DR: In this paper, the authors show that overpressure is widespread in the southern margin of the Junggar Basin, northwestern China, due to rapid sediment deposition, pressure compartmentalization by thick mudrocks, tectonic stress, faulting and folding.
Abstract: Overpressure is widespread in the southern margin of the Junggar Basin, northwestern China. Pressure measurements in drillstem tests and repeated formation tests and estimates from wire-line logs indicate contrasting overpressure values between permeable sandstones and adjacent low-permeability mudrocks. In addition, excess pressure differs among anticlines with similar depth, lithologies, and geologic age, indicating significant lateral changes of overpressure. Major factors controlling overpressure generation and distribution include rapid sediment deposition, pressure compartmentalization by thick mudrocks, tectonic stress, faulting, and folding. Clay transformation and hydrocarbon generation are believed to be insignificant in overpressure generation in the southern Junggar Basin. Numerical modeling of pressure generation and evolution suggests that faulting and stratal tilting associated with folding are the most significant factors in the overpressure generation of a permeable sandstone. The extremely high overpressure (pressure coefficient up to 2.43) may have been caused by hydraulic adjustment within permeable sandstones associated with structural deformation caused by post-Miocene intense tectonic activities.
TL;DR: It is shown that the time delay systems can be stabilized by impulses even if the system matrices are unstable, and several stability criteria are established for both linear and nonlinear impulsive systems with time delay.
Abstract: This paper studies stability problems of a class of impulsive systems with time delay whose linear parts contain unstable system matrices. By using the method of variation of parameters, Lyapunov functions and inequalities, several stability criteria are established for both linear and nonlinear impulsive systems with time delay. It is shown that the time delay systems can be stabilized by impulses even if the system matrices are unstable. Several numerical examples are given to illustrate the results.