Showing papers by "China University of Petroleum published in 2011"
TL;DR: An asymmetric supercapacitor with high energy density has been developed successfully using graphene/MnO2 composite as positive electrode and activated carbon nanofibers (ACN) as negative electrode in a neutral aqueous Na2SO4 electrolyte as mentioned in this paper.
Abstract: Asymmetric supercapacitor with high energy density has been developed successfully using graphene/MnO2 composite as positive electrode and activated carbon nanofibers (ACN) as negative electrode in a neutral aqueous Na2SO4 electrolyte. Due to the high capacitances and excellent rate performances of graphene/MnO2 and ACN, as well as the synergistic effects of the two electrodes, such asymmetric cell exhibits superior electrochemical performances. An optimized asymmetric supercapacitor can be cycled reversibly in the voltage range of 0–1.8 V, and exhibits maximum energy density of 51.1 Wh kg−1, which is much higher than that of MnO2//DWNT cell (29.1 Wh kg−1). Additionally, graphene/MnO2//ACN asymmetric supercapacitor exhibits excellent cycling durability, with 97% specific capacitance retained even after 1000 cycles. These encouraging results show great potential in developing energy storage devices with high energy and power densities for practical applications.
1,768 citations
TL;DR: In this article, a novel visible light-induced g-C3N4/Bi2WO6 composite photocatalysts were synthesized by introducing polymeric g-c3n4.
Abstract: Novel visible light-induced g-C3N4/Bi2WO6 composite photocatalysts were synthesized by introducing polymeric g-C3N4. The obtained g-C3N4/Bi2WO6 products were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, high-resolution transmission electron microscopy, ultraviolet–visible diffuse reflection spectroscopy (DRS), and photoluminescence spectroscopy. The DRS results revealed that the g-C3N4/Bi2WO6 samples had a red shift and strong absorption in the visible light region. The photocatalytic oxidation ability of the novel photocatalyst was evaluated using methyl orange as a target pollutant. The photocatalysts exhibited a significantly enhanced photocatalytic performance in degrading methyl orange. The optimal g-C3N4 content for the photocatalytic activity of the heterojunction structures was determined. The synergic effect between g-C3N4 and Bi2WO6 was found to lead to an improved photo-generated carrier separation. Consequently, the photocatalytic performance of the g-C3N4/Bi2WO6 composites under visible light irradiation (λ > 420 nm) was enhanced. The possible photocatalytic mechanism of the composites was proposed to guide the further improvement of their photocatalytic activity.
678 citations
TL;DR: In this paper, a novel polymeric g-C3N4 photocatalysts loaded with noble metal Ag nanoparticles were prepared via a facile heating method, and they were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), TEM, HRTEM, X-Ray photoelectron spectroscopy (XPS), UV-vis diffuse reflection spectra (DRS), and photoluminescence spectra.
Abstract: Novel polymeric g-C3N4 photocatalysts loaded with noble metal Ag nanoparticles were prepared via a facile heating method. The obtained Ag/g-C3N4 composite products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), UV–vis diffuse reflection spectra (DRS) and photoluminescence spectra (PL). The photocatalytic activities of Ag/g-C3N4 samples were investigated based on the decomposition of methyl orange and hydrogen evolution under visible light irradiation. The XPS results revealed that it was the metallic Ag0 deposited on polymeric g-C3N4 samples. The Ag/g-C3N4 photocatalysts exhibited significantly enhanced photocatalytic performance for the degradation of methyl orange and hydrogen production compared with pure g-C3N4. The optimal Ag content was determined to be 1.0 wt%, and the corresponding hydrogen evolution rate was 10.105 μmol h−1, which exceeded that of pure g-C3N4 by more than 11.7 times. The enhanced photocatalytic performance could be attributed to the synergic effect between Ag and g-C3N4, which promoted the migration efficiency of photo-generated carriers. The proposed mechanism for the enhanced visible light photocatalytic activity of g-C3N4 modified by a small amount of Ag was further confirmed by photoluminescence spectroscopy.
579 citations
TL;DR: In this paper, the gas phase hydrodeoxygenation (HDO) of guaiacol, as a model compound for pyrolysis oil, was tested on a series of novel hydroprocessing catalysts.
Abstract: The gas phase hydrodeoxygenation (HDO) of guaiacol, as a model compound for pyrolysis oil, was tested on a series of novel hydroprocessing catalysts – transition metal phosphides which included Ni2P/SiO2, Fe2P/SiO2, MoP/SiO2, Co2P/SiO2 and WP/SiO2. The turnover frequency based on active sites titrated by the chemisorption of CO followed the order: Ni2P > Co2P > Fe2P, WP, MoP. The major products from hydrodeoxygenation of guaiacol for the most active phosphides were benzene and phenol, with a small amount of methoxybenzene formed. Kinetic studies revealed the formation of reaction intermediates such as catechol and cresol at short contact times. A commercial catalyst 5% Pd/Al2O3 was more active than the metal phosphides at lower contact time but produced only catechol. A commercial CoMoS/Al2O3 deactivated quickly and showed little activity for the HDO of guaiacol at these conditions. Thus, transition metal phosphides are promising materials for catalytic HDO of biofuels.
522 citations
TL;DR: Graphene that had nanomeshes, only one to two graphene layers, and specific surface areas of up to 1654 m(2) g(-1) was produced on gram-scale by template growth on porous MgO layers, which gave excellent electrochemical capacitance, cycle stability and rate performance.
353 citations
TL;DR: 4th generation biofuel production has introduced the “cell factory” concept in this field, and shifted the research paradigm, and there still exists several technical bottlenecks in algae biofuel research and development which can be solved by the use of post-genome tools on these photosynthetic organisms.
Abstract: The ecological footprint and economic performance of the current suite of biofuel production methods make them insufficient to displace fossil fuels and reduce their impact on the inventory of Green House Gas (GHG) in the global atmosphere. Algae metabolic engineering forms the basis for 4th generation biofuel production which can meet this need. The first generation biofuels are known to be made from agricultural products such as corn or sugarcane. The second generation biofuels use all forms of (lingo)cellulosic biomass. The third and fourth generation of biofuel production involves “algae-to-biofuels” technology: the former is basically processing of algae biomass for biofuel production, while the latter is about metabolic engineering of algae for producing biofuels from oxygenic photosynthetic microorganisms. Our review focuses on the research achievement of metabolic engineering of algae for biofuel production. It is concluded that 4th generation biofuel production has introduced the “cell factory” concept in this field, and shifted the research paradigm. There still exists several technical bottlenecks in algae biofuel research and development, which can only be solved by the use of post-genome tools on these photosynthetic organisms.
326 citations
TL;DR: A brief overview on the recent stability results of fractional differential equations and the analytical methods used are provided in this paper, where some conclusions for stability are similar to that of classical integer-order differential equations.
Abstract: Recently, fractional calculus has attracted much attention since it plays an important role in many fields of science and engineering. Especially, the study on stability of fractional differential equations appears to be very important. In this paper, a brief overview on the recent stability results of fractional differential equations and the analytical methods used are provided. These equations include linear fractional differential equations, nonlinear fractional differential equations, fractional differential equations with time-delay. Some conclusions for stability are similar to that of classical integer-order differential equations. However, not all of the stability conditions are parallel to the corresponding classical integer-order differential equations because of non-locality and weak singularities of fractional calculus. Some results and remarks are also included.
314 citations
TL;DR: A comprehensive review of enhancement techniques in electrochemical remediation is given in this paper with a view to providing useful information to researchers and practitioners in this field.
312 citations
309 citations
TL;DR: Biological pretreatment with new complex microbial agents was used to pretreat corn straw at ambient temperature to improve its biodegradability and anaerobic biogas production to enhance the highly efficient biological conversion of corn straw into bioenergy.
257 citations
TL;DR: The fabrication of 3D carbonaceous material composed of 1D carbon nanofibers grown on 2D graphene sheets via a CVD approach in a fluidized bed reactor shows high reversible capacity, high-rate performance, and cycling stability, which is superior to those of pure graphene, natural graphite, and carbon nanotubes.
Abstract: We report on the fabrication of 3D carbonaceous material composed of 1D carbon nanofibers (CNF) grown on 2D graphene sheets (GNS) via a CVD approach in a fluidized bed reactor. Nanographene-constructed carbon nanofibers contain many cavities, open tips, and graphene platelets with edges exposed, providing more extra space for Li(+) storage. More interestingly, nanochannels consisting of graphene platelets arrange almost perpendicularly to the fiber axis, which is favorable for lithium ion diffusion from different orientations. In addition, 3D interconnected architectures facilitate the collection and transport of electrons during the cycling process. As a result, the CNF/GNS hybrid material shows high reversible capacity (667 mAh/g), high-rate performance, and cycling stability, which is superior to those of pure graphene, natural graphite, and carbon nanotubes. The simple CVD approach offers a new pathway for large-scale production of novel hybrid carbon materials for energy storage.
TL;DR: In this paper, a BMP test was used to evaluate biogas production for raw biomass and hydrothermal treated waste, which showed that fruit/vegetable and food waste showed higher methane production than that of cow manure, pig manure, and municipal sewage sludge.
TL;DR: In this article, several SBA-15 silica materials with different pore structures were synthesized and functionalized with poly(ethyleneimine) (PEI), and the as-prepared materials were characterized by XRD, SEM, TG, FT-IR, and N2 physisorption techniques followed by testing for CO2 capture using a N2 stream containing 15.1 v/v% CO2 in the temperature range of 30−75 °C.
Abstract: Several SBA-15 silica materials with different pore structures were synthesized and functionalized with poly(ethyleneimine) (PEI). The as-prepared materials were characterized by XRD, SEM, TG, FT-IR, and N2 physisorption techniques followed by testing for CO2 capture using a N2 stream containing 15.1 v/v% CO2 in the temperature range of 30−75 °C. The results showed that the CO2 adsorption capacity linearly increased with the total pore volume of the SBA-15 phases in the tested temperature range (R2 > 0.94). Temperature also showed a strong influence on CO2 adsorption capacity. SBA-15 material with the largest pore volume (1.14 cm3 g−1) exhibited the largest CO2 adsorption capacity (105.2 mg g−1 adsorbent) with 15.1 v/v% CO2 in N2 at 75 °C and atmospheric pressure. Pore size was found not to be the main factor influencing the CO2 adsorption capacity of these PEI-modified SBA-15 materials. Adsorption−desorption cycles (12) revealed that the adsorbents with PEI loaded inside the pore channels were found to b...
TL;DR: In this paper, three Paleogene syn-rift intervals from the Bohai Bay Basin, the most petroliferous basin in China, were analyzed with sedimentological and geochemical techniques to characterize the lateral source rock heterogeneities, revealing the environmental and ecological changes through geologic time and to construct depositional models for lacustrine source rocks under different tectonic and climatic conditions.
TL;DR: In this paper, the performance of four 1-R-2-undecyl-imidazoline compounds (R CH 2 COOH (A), CH 2 CH 2 OH (B), CH2 CH 2 NH 2 (C) and H (D)) for carbon steel was evaluated by quantum chemistry and molecular mechanics methods.
TL;DR: In this article, the photocatalytic mechanism of the CdS-Bi2WO6 photocatalyst was proposed in order to guide the further improvement of its photocatalysis.
Abstract: Photocatalytic active Bi2WO6 sensitized by CdS quantum dots (QDs) was synthesized via a chemical hydrothermal approach for the first time. The QDs sensitized CdS-Bi2WO6 photocatalysts were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), UV–vis absorption spectroscopy (UV–vis) and photoluminescence spectra (PL). The photocatalytic activities of QDs sensitized CdS-Bi2WO6 samples were investigated based on the decomposition of methyl orange and phenol in aqueous solution under visible light irradiation (λ > 420 nm). The DRS results revealed that CdS-Bi2WO6 samples have a red shift and stronger absorption in the visible light region. After being sensitized by CdS QDs, the Bi2WO6 samples showed the high efficiency for the degradation of methyl orange. The enhanced photocatalytic performance could be attributed to the synergic effect between CdS QDs and Bi2WO6, which promoted the migration efficiency of photo-generated carriers. According to experimental results, the possible photocatalytic mechanism of the CdS-Bi2WO6 photocatalyst was proposed in order to guide the further improvement of its photocatalytic activity.
TL;DR: In this paper, the authors studied a limb coronal shock wave and its associated extreme ultraviolet (EUV) wave that occurred on 2010 June 13 and found that the shock wave appeared clearly only in the channels centered at 193 angstrom and 211 angstrom as a dome-like enhancement propagating ahead of its associated semi-spherical coronal mass ejection (CME) bubble.
Abstract: Taking advantage of both the high temporal and spatial resolutions of the Atmospheric Imaging Assembly on board the Solar Dynamics Observatory, we studied a limb coronal shock wave and its associated extreme ultraviolet (EUV) wave that occurred on 2010 June 13. Our main findings are: (1) the shock wave appeared clearly only in the channels centered at 193 angstrom and 211 angstrom as a dome-like enhancement propagating ahead of its associated semi-spherical coronal mass ejection (CME) bubble; (2) the density compression of the shock is 1.56 according to radio data and the temperature of the shock is around 2.8 MK; (3) the shock wave first appeared at 05: 38 UT, 2 minutes after the associated flare has started and 1 minute after its associated CME bubble appeared; (4) the top of the dome-like shock wave set out from about 1.23 R-circle dot and the thickness of the shocked layer is similar to 2 x 10(4) km; (5) the speed of the shock wave is consistent with a slight decrease from about 600 km s(-1) to 550 km s(-1); and (6) the lateral expansion of the shock wave suggests a constant speed around 400 km s(-1), which varies at different heights and directions. Our findings support the view that the coronal shock wave is driven by the CME bubble, and the on-limb EUV wave is consistent with a fast wave or at least includes the fast wave component.
TL;DR: In this article, three mesocellular silica foam (MCF) materials with different window sizes were prepared and functionalized with polyethyleneimine (PEI) for use as CO2 adsorbents.
TL;DR: This critical review provides a critical discussion of the current state of knowledge of the key factors influencing the solubility of gases in ionic liquids (ILs), including sample purity, experimental methodology, "molecular" characteristics of ILs, temperature and pressure.
Abstract: This critical review provides a critical discussion of the current state of knowledge of the key factors influencing the solubility of gases in ionic liquids (ILs), including sample purity, experimental methodology, “molecular” characteristics of ILs, temperature and pressure. The review starts with a brief introduction to the current developments and the existing problems in the studies of the gas solubility in ILs. Then, the experimental, computational and theoretical developments in conformational equilibria of ions, in nanosegregated polar and nonpolar domains in ILs, and in the mechanisms for dissolution of gases in ILs are discussed and subsequently collaborated together with our freeze-fracture transmission electron microscopic and Raman measurements to propose the new microscopic mechanism for dissolving the gases in ILs. Next, a critical and quantitative analysis of the influences of the sample purity and the experimental methodology on the gas solubility is made so that the “real” relationships between structure and solubility property can be revealed. In addition, a systematic and deeper understanding of how the “molecular” features of the ILs, the temperature, and the pressure influence the gas solubility is provided at the molecular level. In the section of concluding remarks, the comments are made on the molecular criteria for the future design of the ILs to enhance the gas solubility by specifically optimizing the molecular characteristics of the ILs (265 references).
TL;DR: A series of catalysts of 3D ordered macroporous (3DOM) Ce0.8Zr 0.04/Ce0.2O2-supported gold nanoparticles with controllable sizes were successfully synthesized by the facile method of gas bubbling-assisted membrane reduction (GBMR) as discussed by the authors.
Abstract: A series of catalysts of three-dimensionally ordered macroporous (3DOM) Ce0.8Zr0.2O2-supported gold nanoparticles with controllable sizes were successfully synthesized by the facile method of gas bubbling-assisted membrane reduction (GBMR). All the catalysts possess well-defined 3DOM structures, which consist of interconnected networks of spherical voids, and the Au nanoparticles are well dispersed and supported on the inner wall of the uniform macropore. The relationship between Au particle sizes and the ability to adsorb and activate oxygen was characterized by means of O2-TPD and XPS. The results show that the active oxygen species (O−) and gold ions with oxidation state of Au+ are essential for soot oxidation reaction. 3DOM Au0.04/Ce0.8Zr0.2O2catalyst with Au particle size of 2–3 nm has the strong capability of adsorption and activation of oxygen. Thus, it exhibits super-catalytic activity for diesel soot oxidation, especially at low temperature. The reaction pathways of catalytic soot oxidation in the presence or absence of NO can be outlined as follows: at low temperature ( 250 °C), the catalytic activity is strongly related to the NO gas, because NO2 derived from NO oxidation is used as intermediate to catalyze soot oxidation.
TL;DR: In this paper, a 3D-ordered macroporous (3DOM) La1−xKxCoO3 (x = 0-0.3) perovskite-type oxide catalysts with large pore sizes and interconnected macroporic frameworks were successfully synthesized by a novel method of carboxy-modified colloidal crystal templates (CMCCT).
TL;DR: In this paper, the stability and stability mechanism of synthetic W/O crude oil emulsion stabilized by polymer and surfactant was investigated and it was shown that polymer concentration is the key factor to stabilize the synthetic crude oil.
TL;DR: The cytotoxicity evaluation revealed that Ti NiAg alloy extract induced slight toxicity to cells, but the viability of experimental cells was similar to or higher than that of TiNi alloy extract, and the corresponding antibacterial mechanism for the TiNiAg alloy is discussed.
TL;DR: In this paper, the effect of temperature on adsorption of CO2, CH4, CO, and N2 and separation of their binary mixtures in ZIF-8 were investigated using experimental measurements combining with molecular simulations.
TL;DR: Changes in hydrophobic length and swapping of L and I can alter the size and shape of the self-assembled nanostructures from these simple peptide amphiphiles, demonstrating a strong tendency of I groups to promote the growth of β-sheet hydrogen bonding and the subsequent formation of nanofibrillar shapes.
Abstract: The interplay between hydrogen bonding, hydrophobic interaction and the molecular geometry of amino acid side-chains is crucial to the development of nanostructures of short peptide amphiphiles. An important step towards developing their practical use is to understand how different amino acid side-chains tune hydrophobic interaction and hydrogen bonding and how this process leads to the control of the size and shape of the nanostructures. In this study, we have designed and synthesized three sets of short amphiphilic peptides (I(3)K, LI(2)K and L(3)K; L(3)K, L(4)K and L(5)K; I(3)K, I(4)K and I(5)K) and investigated how I and L affected their self-assembly in aqueous solution. The results have demonstrated a strong tendency of I groups to promote the growth of β-sheet hydrogen bonding and the subsequent formation of nanofibrillar shapes. All I(m)K (m = 3-5) peptides assembled into nanofibers with consistent β-sheet conformation, whereas the nanofiber diameters decreased as m increased due to geometrical constraint in peptide chain packing. In contrast, L groups had a weak tendency to promote β-sheet structuring and their hydrophobicity became dominant and resulted in globular micelles in L(3)K assembly. However, increase in the number of hydrophobic sequences to L(5)K induced β-sheet conformation due to the cooperative hydrophobic effect and the consequent formation of long nanofibers. The assembly of L(4)K was, therefore, intermediate between L(3)K and L(5)K, similar to the case of LI(2)K within the set of L(3)K, LI(2)K and I(3)K, with a steady transition from the dominance of hydrophobic interaction to hydrogen bonding. Thus, changes in hydrophobic length and swapping of L and I can alter the size and shape of the self-assembled nanostructures from these simple peptide amphiphiles.
TL;DR: The use of natural gas in China is still relatively immature, as gas production only supplies a low percentage of the domestic energy system as discussed by the authors. In contrast, the Chinese economy mainly relies on coal.
TL;DR: The aluminum-silicon distribution and mesoporosity of Y zeolites prepared by sequential NaOH desilication and ammonium hexafluorosilicate (AHFS) dealumination are compared with that of Y samples prepared via AHFS only as mentioned in this paper.
TL;DR: In this article, the origin and evolution of reservoir wettability were critically reviewed to better understand the complexity of wetability due to interactions in crude oil-brine-rock system, with introduction of different wetting states and their influence on fluid distribution in pore spaces.
TL;DR: In this paper, the authors investigated the shale hydration inhibitive properties of polyether diamine (PEDA) in drilling fluid system and showed that the inhibition properties of PEDA are superior to potassium chloride, and can be improved with decrease of pH value.
TL;DR: In this paper, the number of oxygen-containing functional groups (OCFGs) on the surface of a commercial activated carbon (AC) was maximized using ammonium persulfate ((NH4)2S2O8, APS) as an oxidant.