The hollow strontium carbonate pompons was synthesized for the first time by a controlled reaction precipitation method with sodium dodecyl benzene sulfonate(SDBS)and polyvinyl pyrrolidone(PVP)work together as templat...The hollow strontium carbonate pompons was synthesized for the first time by a controlled reaction precipitation method with sodium dodecyl benzene sulfonate(SDBS)and polyvinyl pyrrolidone(PVP)work together as template.The sampled particles were characterized by scanning electron microscopy(SEM),transmission electron microscopy(TEM),nitrogen adsorption-desorption measurement,X-ray diffraction(XRD),Energy dispersive X-Ray spectroscopy(EDX),Fourier transform infrared spectroscopy(FTIR),Thermogravimetric analysis and differential scanning calorimetry(TGA-DSC),etc.It is shown that the assynthesized hollow strontium carbonate pompons with the size of about 2μm consist of flake-like particles under the optimal reaction conditions.The formation mechanism of hollow strontium carbonate pompons was preliminarily explored.展开更多
The production of propylene carbonate (PC) from urea and 1,2-propanediol (PG) was investigated in a batch process. The catalytic performances of zinc chloride and magnesium chloride were investigated for this reac...The production of propylene carbonate (PC) from urea and 1,2-propanediol (PG) was investigated in a batch process. The catalytic performances of zinc chloride and magnesium chloride were investigated for this reaction system. The influences of various operation conditions on the PC yield were explored. In this work, MgCl2 and ZnCl2 showed the excellent catalytic activity toward PC synthesis, and the yields of propylene carbonate reached 96.5% and 92.4%, respectively. The optimum reaction conditions were as follows: ethanol/urea molar ratio of 4, catalyst concentration of 1.5%, reaction temperature of 160 ℃, reaction time of 3 h, respectively. The route from urea and 1,2-propanediol shows advantages, such as mild reaction condition and safe operation. The catalytic system is environmentally benign.展开更多
The carbonate reservoirs in the Tarim Basin are characterized by low matrix-porosity,heterogeneity and anisotropy,which make it difficult to predict and evaluate these reservoirs.The reservoir formations in Lundong ar...The carbonate reservoirs in the Tarim Basin are characterized by low matrix-porosity,heterogeneity and anisotropy,which make it difficult to predict and evaluate these reservoirs.The reservoir formations in Lundong area experienced a series of diagenesis and tectonic evolution stages.And secondary storage spaces such as fractures and dissolution caves were developed while nearly all the primary pores have disappeared.Based on a summary of different types of storage spaces and their responses in conventional logs,FMI and full waveform sonic logs which are sensitive to different reservoirs,the comprehensive probability index (CPI) method is applied to evaluating the reservoirs and a standard of reservoir classification is established.By comparing the evaluation results with actual welllogging results,the method has proven to be practical for formation evaluation of carbonate reservoirs,especially for the fractured carbonate reservoirs.In reservoir fluid identification,the multivariate stepwise discriminant analysis (MSDA) method is introduced.Combining the CPI method and MSDA method,comprehensive formation evaluation has been performed for fractured and caved carbonate reservoirs in the Tarim Basin.Additionally,on the basis of secondary pore inversion results,another new method of formation evaluation is also proposed in the discussion part of this paper.Through detailed application result analysis,the method shows a promising capability for formation evaluation of complex carbonate reservoirs dominated by various secondary pores such as holes,caves,and cracks.展开更多
The electrocatalytic synthesis of propylene carbonate(PC) from CO2 and propylene oxide(PO) was studied under mild conditions(PCO2=1.01×105 Pa, t=25 ℃). Influences of solvents, supporting electrolytes, the ...The electrocatalytic synthesis of propylene carbonate(PC) from CO2 and propylene oxide(PO) was studied under mild conditions(PCO2=1.01×105 Pa, t=25 ℃). Influences of solvents, supporting electrolytes, the passed charge, the nature of electrodes and the current density(j) on the yield of PC were investigated to optimize the electrolytic conditions, with the maximal yield to be 46.2%, the selectivity of propylene carbonate is 100%. The reduction of propylene oxide in the absence and presence of CO2 was examined by cyclic voltammetry. The mechanism of the reaction initiated by the synergistic effect of halides ions of supporting electrolytes with nucleophilicity and the metal ions from scarification anode with Lewis acid acidity was proposed on the basis of our results.展开更多
Carbonate reservoirs worldwide are complex in structure,diverse in form,and highly heterogeneous.Based on these characteristics,the reservoir stimulation technologies and fluid flow characteristics of carbonate reserv...Carbonate reservoirs worldwide are complex in structure,diverse in form,and highly heterogeneous.Based on these characteristics,the reservoir stimulation technologies and fluid flow characteristics of carbonate reservoirs are briefly described in this study.The development methods and EOR technologies of carbonate reservoirs are systematically summarized,the relevant mechanisms are analyzed,and the application status of oil fields is catalogued.The challenges in the development of carbonate reservoirs are discussed,and future research directions are explored.In the current development processes of carbonate reservoirs,water flooding and gas flooding remain the primary means but are often prone to channeling problems.Chemical flooding is an effective method of tertiary oil recovery,but the harsh formation conditions require high-performance chemical agents.The application of emerging technologies can enhance the oil recovery efficiency and environmental friendliness to a certain extent,which is welcome in hard-to-recover areas such as heavy oil reservoirs,but the economic cost is often high.In future research on EOR technologies,flow field control and flow channel plugging will be the potential directions of traditional development methods,and the application of nanoparticles will revolutionize the chemical EOR methods.On the basis of diversified reservoir stimulation,combined with a variety of modern data processing schemes,multichannel EOR technologies are being developed to realize the systematic,intelligent,and cost-effective development of carbonate reservoirs.展开更多
In this paper,we have developed a highly efficient method for the direct preparation of propylene carbonate from propylene and carbon dioxide(CO2) using quaternary ammonium heteropolyphosphatotungstate–quaternary a...In this paper,we have developed a highly efficient method for the direct preparation of propylene carbonate from propylene and carbon dioxide(CO2) using quaternary ammonium heteropolyphosphatotungstate–quaternary ammonium halide catalytic system with anhydrous hydrogen peroxide as an oxidant through one-pot two-step process.The effects of the amount of tetrabutylammonium bromide(TBAB),the concentration of hydrogen peroxide and other reaction conditions were investigated.The catalyst system gave an optimum propylene oxide yield(91%) at75°C in oxidation step and the highest propylene carbonate yield(99%) at 140°C and 3.0 MPa in cycloaddition step.Based on the results,a reaction mechanism has been proposed.展开更多
Propylene carbonate was synthesized from supercritical carbon dioxide (SC-CO2)/ propylene oxide mixture with phthalocyaninatoaluminium chloride (ClAlPc)/ tetrabutylstmmonium bromide (n-Bu4NBr) as catalyst. The high ra...Propylene carbonate was synthesized from supercritical carbon dioxide (SC-CO2)/ propylene oxide mixture with phthalocyaninatoaluminium chloride (ClAlPc)/ tetrabutylstmmonium bromide (n-Bu4NBr) as catalyst. The high rate of reaction was attributed to rapid diffusion and the high miscibility of propylene oxide in SC-CO2 under employed conditions. Various reaction periods present different formation rate of propylene carbonate, mainly due to the existence of phase change during the reaction. The experimental results demonstrate that SC-CO2 could be used as not only an environmentally benign solvent but also a carbon precursor in synthesis.展开更多
A series of Zn–Ca–Al oxides with different CaO and ZnO contents have been prepared and evaluated in the synthesis of propylene carbonate(PC) from 1,2-propylene glycol(PG) and urea in a batch reactor. The effect of c...A series of Zn–Ca–Al oxides with different CaO and ZnO contents have been prepared and evaluated in the synthesis of propylene carbonate(PC) from 1,2-propylene glycol(PG) and urea in a batch reactor. The effect of catalyst composition, basicity and reaction process parameters such as temperature, catalyst dose, molar ratio of PG to urea, purge gas flow and reaction time has been studied to find suitable reaction conditions for the PC synthesis. The PC selectivity and yield under the desired conditions could reach 98.4% and 90.8%, respectively. The best performing catalyst also exhibited a good reusability without appreciable loss in the PC selectivity and yield after five consecutive reaction runs. In addition, a stepwise reaction pathway involving a 2-hydroxypropyl carbamate intermediate was proposed for the urea alcoholysis to PC in the presence of Zn–Ca–Al catalysts, according to the time dependences of reaction intermediates and products.展开更多
The completely degradable nanocomposites comprised of poly(propylene carbonate)(PPC) and organo-modified rectorite (OREC) were prepared by direct melt intercalation. The structure and mechanical properties of PPC/OREC...The completely degradable nanocomposites comprised of poly(propylene carbonate)(PPC) and organo-modified rectorite (OREC) were prepared by direct melt intercalation. The structure and mechanical properties of PPC/OREC nanocomposites were investigated. The wide-angle X-ray diffraction (WAXD) results show that the galleries distance of OREC is increased after PPC and OREC melt intercalation, which indicates that PPC molecular chain has intercalated into the layers of OREC. The PPC/OREC nanocomposites with lower OREC content show an increase in thermal decomposition temperature compared with pure PPC. The tensile strength and impact strength of PPC/OREC nanocomposites are improved. When the mass fraction of OREC is 4%, the tensile strength and impact strength of the PPC/OREC nanocomposite increase by 22.86% and 48.58% respectively, compared with pure PPC.展开更多
Rock typing is an important tool in evaluation and performance prediction of reservoirs.Different techniques such as flow zone indicator(FZI),FZI~*and Winland methods are used to categorize reservoir rocks into distin...Rock typing is an important tool in evaluation and performance prediction of reservoirs.Different techniques such as flow zone indicator(FZI),FZI~*and Winland methods are used to categorize reservoir rocks into distinct rock types.Generally,these methods are applied to petrophysical data that are measured at a pressure other than reservoir pressure.Since the pressure changes the pore structure of rock,the effect of overburden pressure on rock typing should be considered.In this study,porosity and permeability of 113 core samples were measured at five different pressures.To investigate the effect of pressure on determination of rock types,FZI,FZI~*and Winland methods were applied.Results indicated that although most of the samples remain in the same rock type when pressure changes,some of them show different trends.These are related to the mineralogy and changes in pore system of the samples due to pressure change.Additionally,the number of rock types increases with increasing pressure.Furthermore,the effect of overburden pressure on determination of rock types is more clearly observed in the Winland and FZI~*methods.Also,results revealed that a more precise reservoir dynamic simulation can be obtained by considering the reservoir rock typing process at reservoir conditions.展开更多
Propylene carbonate (PC) has a great potential to be used as an energy storage medium in the compact pulsed power sources due to its high dielectric constant and large resistivity. We investigate both the positive a...Propylene carbonate (PC) has a great potential to be used as an energy storage medium in the compact pulsed power sources due to its high dielectric constant and large resistivity. We investigate both the positive and negative breakdown characteristics of PC. The streamer patterns are obtained by ultra-high-speed cameras. The experimental results show that the positive breakdown voltage of PC is about 135% higher than the negative one, which is abnormal compared with the common liquid. The shape of the positive streamer is filamentary and branchy, while the negative streamer is tree-like and less branched. According to these experimental results, a charge layer structure model at the interface between the metal electrode and liquid is presented. It is suggested that the abnormal polarity effect basically arises from the electric field strength difference in the interface between both electrodes and PC. What is more, the recombination radiation and photoionization also play an important role in the whole discharge process.展开更多
Cycloaddition of carbon dioxide and propylene oxide to propylene carbonate catalyzed by tetra-tert-butyl metal phthalocyanine in the presence of tributylamine (TBA) shows higher yield than catalyzed by unsubstituted m...Cycloaddition of carbon dioxide and propylene oxide to propylene carbonate catalyzed by tetra-tert-butyl metal phthalocyanine in the presence of tributylamine (TBA) shows higher yield than catalyzed by unsubstituted metal phthalocyanine. Comparing different catalysts of diverse metals, (t-Bu)4PcMg is more active than (t-Bu)4PcFe. But (t-Bu)4PcCo and (t-Bu)4PcNi only have low catalytic activities towards the reaction. Moreover, the yield will increase as the temperature increases.展开更多
Many attempts have been made to control the regioselectivity for olefin poly- merization by varying the structures of ligands in catalysts. The regioselectivity of propylene polymerization was investigated by replacin...Many attempts have been made to control the regioselectivity for olefin poly- merization by varying the structures of ligands in catalysts. The regioselectivity of propylene polymerization was investigated by replacing a nitrogen atom in the Pd(II) diimine catalyst with an oxygen atom from density functional theory method at the B3LYP/LANL2DZ level. The results show that the 1,2-insertion becomes a rival mechanism to the 2,1-insertion when the nitrogen atom is replaced by the oxygen atom leading to an asymmetric environment in the catalyst, and that the steric effect in the asymmetrical catalyst plays an important part in the polymerization. The insertion barrier from 2-O is much higher than that from 2-N. A pyramid transition state was characterized for the catalyst to convert 2-O back to 2-N through internal rotation. The propylene prefers to coordinate at the opposite side of O in the catalyst. This is the driving force for the internal rotation. The results are significant for isotactic and syndiotactic polymerization.展开更多
Understanding the mechanism of the interfacial reaction between the cathode material and the electrolyte is a significant work because the interfacial reaction is an important factor affecting the stability,capacity,a...Understanding the mechanism of the interfacial reaction between the cathode material and the electrolyte is a significant work because the interfacial reaction is an important factor affecting the stability,capacity,and cycling performance of Li-ion batteries.In this work,spin-polarized density functional theory calculations with on-site Coulomb energy have been employed to study the adsorption of electrolyte components propylene carbonate(PC)on the LiMn2O4(100)surface.The findings show that the PC molecule prefers to interact with the Mn atom on the LiMn2O4(100)surface via the carbonyl oxygen(Oc),with the adsorption energy of−1.16 eV,which is an exothermic reaction.As the adsorption of organic molecule PC increases the Mn atoms coordination with O atoms on the(100)surface,the Mn3+ions on the surface lose charge and the reactivity is substantially decreased,which improves the stability of the surface and benefits the cycling performance.展开更多
The cation—conductive blends plasticized with propylene carbonate were prepared. The blends exhibited good mechanical strength and single—cation conduction over a wide range of plasticizer composition. The plasticiz...The cation—conductive blends plasticized with propylene carbonate were prepared. The blends exhibited good mechanical strength and single—cation conduction over a wide range of plasticizer composition. The plasticizer not only increases the conductivity of the blends but also decreases the electrochemical interface resistance between the blend and lithium electrode. The carrier in the blends obviously grows in number.展开更多
Copper azide(CA), as a primary explosive with high energy density, has not been practically used so far because of its high electrostatic sensitivity. The Cu2O@HKUST-1 core-shell structure hybrid material was synthesi...Copper azide(CA), as a primary explosive with high energy density, has not been practically used so far because of its high electrostatic sensitivity. The Cu2O@HKUST-1 core-shell structure hybrid material was synthesized by the “bottle around ship” methodology in this research by regulating the dissolution rate of Cu2O and the generation rate of metal-organic framework(MOF) materials. Cu2O@HKUST-1 was carbonized to form a Cu O@porous carbon(CuO@PC) composite material. CuO@PC was synthesized into a copper azide(CA) @PC composite energetic material through a gas-solid phase in-situ azidation reaction.CA is encapsulated in PC framework, which acts as a nanoscale Faraday cage, and its excellent electrical conductivity prevents electrostatic charges from accumulating on the energetic material’s surface. The CA@PC composite energetic material has a CA content of 89.6%, and its electrostatic safety is nearly 30times that of pure CA(1.47 mJ compared to 0.05 mJ). CA@PC delivers an outstanding balance of safety and energy density compared to similar materials.展开更多
During the Folin Ciocalteu (F-C) micro-assay for the determination of phenolics in the presence of methanol, fine solids can form. In a previous paper, we hypothesized that the interference from alcohol on the F-C rea...During the Folin Ciocalteu (F-C) micro-assay for the determination of phenolics in the presence of methanol, fine solids can form. In a previous paper, we hypothesized that the interference from alcohol on the F-C reaction can be minimized depending on the particular procedure used to reach the alkalinity condition. In order to demonstrate our hypothesis we studied, by spectrophotometrically monitoring, the time-behaviour of the reactions carried out in the presence of different methanol concentrations at the same alkalinity condition from two protocols. The results showed that the interfering effect of methanol on the F-C micro-method can be affect and even prevented depending on working conditions. In particular, the formation of fine solids can be delayed, slowed down and prevented depending on the initial carbonate concentration used. We have explained why the initial carbonate concentration, used to reach the final alkalinity condition, plays an important role in the F-C reaction carried out in the presence of methanol. Moreover, the results from real-time monitoring showed that, differently from traditional F-C procedure, our procedure allows us to carry out the F-C micro method in the presence of 6% methanol, as an extreme concentration, reading the absorbance at real time 24 min. The real-time monitoring of absorbance can be considered as a useful means to explore the effect of other parameters on precipitate formation caused by the presence of methanol in the F-C reaction.展开更多
基金Funded by the National Natural Science Foundation of China(No.22002143)the Natural Science Foundation of Shanxi Province of China(No.201901D211223)the Postgraduate Students Scientific Research Project of North University of China(No.20201766)。
文摘The hollow strontium carbonate pompons was synthesized for the first time by a controlled reaction precipitation method with sodium dodecyl benzene sulfonate(SDBS)and polyvinyl pyrrolidone(PVP)work together as template.The sampled particles were characterized by scanning electron microscopy(SEM),transmission electron microscopy(TEM),nitrogen adsorption-desorption measurement,X-ray diffraction(XRD),Energy dispersive X-Ray spectroscopy(EDX),Fourier transform infrared spectroscopy(FTIR),Thermogravimetric analysis and differential scanning calorimetry(TGA-DSC),etc.It is shown that the assynthesized hollow strontium carbonate pompons with the size of about 2μm consist of flake-like particles under the optimal reaction conditions.The formation mechanism of hollow strontium carbonate pompons was preliminarily explored.
基金supported by the National Natural Science Fund for Distinguished Young Scholars of China(No.20625308).
文摘The production of propylene carbonate (PC) from urea and 1,2-propanediol (PG) was investigated in a batch process. The catalytic performances of zinc chloride and magnesium chloride were investigated for this reaction system. The influences of various operation conditions on the PC yield were explored. In this work, MgCl2 and ZnCl2 showed the excellent catalytic activity toward PC synthesis, and the yields of propylene carbonate reached 96.5% and 92.4%, respectively. The optimum reaction conditions were as follows: ethanol/urea molar ratio of 4, catalyst concentration of 1.5%, reaction temperature of 160 ℃, reaction time of 3 h, respectively. The route from urea and 1,2-propanediol shows advantages, such as mild reaction condition and safe operation. The catalytic system is environmentally benign.
基金co-supported by the National Basic Research Program of China(Grant No.2011CB201103)the National Science and Technology Major Project(GrantNo.2011ZX05004003)
文摘The carbonate reservoirs in the Tarim Basin are characterized by low matrix-porosity,heterogeneity and anisotropy,which make it difficult to predict and evaluate these reservoirs.The reservoir formations in Lundong area experienced a series of diagenesis and tectonic evolution stages.And secondary storage spaces such as fractures and dissolution caves were developed while nearly all the primary pores have disappeared.Based on a summary of different types of storage spaces and their responses in conventional logs,FMI and full waveform sonic logs which are sensitive to different reservoirs,the comprehensive probability index (CPI) method is applied to evaluating the reservoirs and a standard of reservoir classification is established.By comparing the evaluation results with actual welllogging results,the method has proven to be practical for formation evaluation of carbonate reservoirs,especially for the fractured carbonate reservoirs.In reservoir fluid identification,the multivariate stepwise discriminant analysis (MSDA) method is introduced.Combining the CPI method and MSDA method,comprehensive formation evaluation has been performed for fractured and caved carbonate reservoirs in the Tarim Basin.Additionally,on the basis of secondary pore inversion results,another new method of formation evaluation is also proposed in the discussion part of this paper.Through detailed application result analysis,the method shows a promising capability for formation evaluation of complex carbonate reservoirs dominated by various secondary pores such as holes,caves,and cracks.
基金Supported by the National Natural Science Foundation of China(No.20973065)the Fund of Basic Research in Natural Science Issued by Shanghai Municipal Committee of Science+4 种基金 China(No.08dj1400100)the Shanghai Leading Project China (No.B409)the Foundation of Outstanding Young Talent in University of Anhui Province China No.2010SQRL042)
文摘The electrocatalytic synthesis of propylene carbonate(PC) from CO2 and propylene oxide(PO) was studied under mild conditions(PCO2=1.01×105 Pa, t=25 ℃). Influences of solvents, supporting electrolytes, the passed charge, the nature of electrodes and the current density(j) on the yield of PC were investigated to optimize the electrolytic conditions, with the maximal yield to be 46.2%, the selectivity of propylene carbonate is 100%. The reduction of propylene oxide in the absence and presence of CO2 was examined by cyclic voltammetry. The mechanism of the reaction initiated by the synergistic effect of halides ions of supporting electrolytes with nucleophilicity and the metal ions from scarification anode with Lewis acid acidity was proposed on the basis of our results.
基金supported by the Innovation Project for Graduates in UPC(Grant YCX2019016)the National Natural Science Foundation of China(Nos.51774306 and 51974346)+1 种基金the Science and Technology Support Plan for Youth Innovation of University in Shandong Province under Grant 2019KJH002the Major Scientific and Technological Projects of CNPC under Grant ZD2019-183-008。
文摘Carbonate reservoirs worldwide are complex in structure,diverse in form,and highly heterogeneous.Based on these characteristics,the reservoir stimulation technologies and fluid flow characteristics of carbonate reservoirs are briefly described in this study.The development methods and EOR technologies of carbonate reservoirs are systematically summarized,the relevant mechanisms are analyzed,and the application status of oil fields is catalogued.The challenges in the development of carbonate reservoirs are discussed,and future research directions are explored.In the current development processes of carbonate reservoirs,water flooding and gas flooding remain the primary means but are often prone to channeling problems.Chemical flooding is an effective method of tertiary oil recovery,but the harsh formation conditions require high-performance chemical agents.The application of emerging technologies can enhance the oil recovery efficiency and environmental friendliness to a certain extent,which is welcome in hard-to-recover areas such as heavy oil reservoirs,but the economic cost is often high.In future research on EOR technologies,flow field control and flow channel plugging will be the potential directions of traditional development methods,and the application of nanoparticles will revolutionize the chemical EOR methods.On the basis of diversified reservoir stimulation,combined with a variety of modern data processing schemes,multichannel EOR technologies are being developed to realize the systematic,intelligent,and cost-effective development of carbonate reservoirs.
文摘In this paper,we have developed a highly efficient method for the direct preparation of propylene carbonate from propylene and carbon dioxide(CO2) using quaternary ammonium heteropolyphosphatotungstate–quaternary ammonium halide catalytic system with anhydrous hydrogen peroxide as an oxidant through one-pot two-step process.The effects of the amount of tetrabutylammonium bromide(TBAB),the concentration of hydrogen peroxide and other reaction conditions were investigated.The catalyst system gave an optimum propylene oxide yield(91%) at75°C in oxidation step and the highest propylene carbonate yield(99%) at 140°C and 3.0 MPa in cycloaddition step.Based on the results,a reaction mechanism has been proposed.
文摘Propylene carbonate was synthesized from supercritical carbon dioxide (SC-CO2)/ propylene oxide mixture with phthalocyaninatoaluminium chloride (ClAlPc)/ tetrabutylstmmonium bromide (n-Bu4NBr) as catalyst. The high rate of reaction was attributed to rapid diffusion and the high miscibility of propylene oxide in SC-CO2 under employed conditions. Various reaction periods present different formation rate of propylene carbonate, mainly due to the existence of phase change during the reaction. The experimental results demonstrate that SC-CO2 could be used as not only an environmentally benign solvent but also a carbon precursor in synthesis.
基金Supported by the Changcheng Scholars Program of Beijing(CIT&TCD 20150316)
文摘A series of Zn–Ca–Al oxides with different CaO and ZnO contents have been prepared and evaluated in the synthesis of propylene carbonate(PC) from 1,2-propylene glycol(PG) and urea in a batch reactor. The effect of catalyst composition, basicity and reaction process parameters such as temperature, catalyst dose, molar ratio of PG to urea, purge gas flow and reaction time has been studied to find suitable reaction conditions for the PC synthesis. The PC selectivity and yield under the desired conditions could reach 98.4% and 90.8%, respectively. The best performing catalyst also exhibited a good reusability without appreciable loss in the PC selectivity and yield after five consecutive reaction runs. In addition, a stepwise reaction pathway involving a 2-hydroxypropyl carbamate intermediate was proposed for the urea alcoholysis to PC in the presence of Zn–Ca–Al catalysts, according to the time dependences of reaction intermediates and products.
文摘The completely degradable nanocomposites comprised of poly(propylene carbonate)(PPC) and organo-modified rectorite (OREC) were prepared by direct melt intercalation. The structure and mechanical properties of PPC/OREC nanocomposites were investigated. The wide-angle X-ray diffraction (WAXD) results show that the galleries distance of OREC is increased after PPC and OREC melt intercalation, which indicates that PPC molecular chain has intercalated into the layers of OREC. The PPC/OREC nanocomposites with lower OREC content show an increase in thermal decomposition temperature compared with pure PPC. The tensile strength and impact strength of PPC/OREC nanocomposites are improved. When the mass fraction of OREC is 4%, the tensile strength and impact strength of the PPC/OREC nanocomposite increase by 22.86% and 48.58% respectively, compared with pure PPC.
文摘Rock typing is an important tool in evaluation and performance prediction of reservoirs.Different techniques such as flow zone indicator(FZI),FZI~*and Winland methods are used to categorize reservoir rocks into distinct rock types.Generally,these methods are applied to petrophysical data that are measured at a pressure other than reservoir pressure.Since the pressure changes the pore structure of rock,the effect of overburden pressure on rock typing should be considered.In this study,porosity and permeability of 113 core samples were measured at five different pressures.To investigate the effect of pressure on determination of rock types,FZI,FZI~*and Winland methods were applied.Results indicated that although most of the samples remain in the same rock type when pressure changes,some of them show different trends.These are related to the mineralogy and changes in pore system of the samples due to pressure change.Additionally,the number of rock types increases with increasing pressure.Furthermore,the effect of overburden pressure on determination of rock types is more clearly observed in the Winland and FZI~*methods.Also,results revealed that a more precise reservoir dynamic simulation can be obtained by considering the reservoir rock typing process at reservoir conditions.
基金Supported by the National Natural Science Foundation of China under Grant No 51677190the Hunan Provincial Natural Science Foundation of China under Grant No 2017JJ1005
文摘Propylene carbonate (PC) has a great potential to be used as an energy storage medium in the compact pulsed power sources due to its high dielectric constant and large resistivity. We investigate both the positive and negative breakdown characteristics of PC. The streamer patterns are obtained by ultra-high-speed cameras. The experimental results show that the positive breakdown voltage of PC is about 135% higher than the negative one, which is abnormal compared with the common liquid. The shape of the positive streamer is filamentary and branchy, while the negative streamer is tree-like and less branched. According to these experimental results, a charge layer structure model at the interface between the metal electrode and liquid is presented. It is suggested that the abnormal polarity effect basically arises from the electric field strength difference in the interface between both electrodes and PC. What is more, the recombination radiation and photoionization also play an important role in the whole discharge process.
文摘Cycloaddition of carbon dioxide and propylene oxide to propylene carbonate catalyzed by tetra-tert-butyl metal phthalocyanine in the presence of tributylamine (TBA) shows higher yield than catalyzed by unsubstituted metal phthalocyanine. Comparing different catalysts of diverse metals, (t-Bu)4PcMg is more active than (t-Bu)4PcFe. But (t-Bu)4PcCo and (t-Bu)4PcNi only have low catalytic activities towards the reaction. Moreover, the yield will increase as the temperature increases.
基金This work was supported by the Natural Science Foundation of Heilongjiang Province (No. B0313) and Research Foundation of China University of Mining and Technology
文摘Many attempts have been made to control the regioselectivity for olefin poly- merization by varying the structures of ligands in catalysts. The regioselectivity of propylene polymerization was investigated by replacing a nitrogen atom in the Pd(II) diimine catalyst with an oxygen atom from density functional theory method at the B3LYP/LANL2DZ level. The results show that the 1,2-insertion becomes a rival mechanism to the 2,1-insertion when the nitrogen atom is replaced by the oxygen atom leading to an asymmetric environment in the catalyst, and that the steric effect in the asymmetrical catalyst plays an important part in the polymerization. The insertion barrier from 2-O is much higher than that from 2-N. A pyramid transition state was characterized for the catalyst to convert 2-O back to 2-N through internal rotation. The propylene prefers to coordinate at the opposite side of O in the catalyst. This is the driving force for the internal rotation. The results are significant for isotactic and syndiotactic polymerization.
基金Project supported by the National Natural Science Foundation of China(Grant No.51962010).
文摘Understanding the mechanism of the interfacial reaction between the cathode material and the electrolyte is a significant work because the interfacial reaction is an important factor affecting the stability,capacity,and cycling performance of Li-ion batteries.In this work,spin-polarized density functional theory calculations with on-site Coulomb energy have been employed to study the adsorption of electrolyte components propylene carbonate(PC)on the LiMn2O4(100)surface.The findings show that the PC molecule prefers to interact with the Mn atom on the LiMn2O4(100)surface via the carbonyl oxygen(Oc),with the adsorption energy of−1.16 eV,which is an exothermic reaction.As the adsorption of organic molecule PC increases the Mn atoms coordination with O atoms on the(100)surface,the Mn3+ions on the surface lose charge and the reactivity is substantially decreased,which improves the stability of the surface and benefits the cycling performance.
文摘The cation—conductive blends plasticized with propylene carbonate were prepared. The blends exhibited good mechanical strength and single—cation conduction over a wide range of plasticizer composition. The plasticizer not only increases the conductivity of the blends but also decreases the electrochemical interface resistance between the blend and lithium electrode. The carrier in the blends obviously grows in number.
基金the financial support by Postgraduate Research & Practice Innovation Program from Jiangsu Science and Technology Department under Grant number KYCX19_0320。
文摘Copper azide(CA), as a primary explosive with high energy density, has not been practically used so far because of its high electrostatic sensitivity. The Cu2O@HKUST-1 core-shell structure hybrid material was synthesized by the “bottle around ship” methodology in this research by regulating the dissolution rate of Cu2O and the generation rate of metal-organic framework(MOF) materials. Cu2O@HKUST-1 was carbonized to form a Cu O@porous carbon(CuO@PC) composite material. CuO@PC was synthesized into a copper azide(CA) @PC composite energetic material through a gas-solid phase in-situ azidation reaction.CA is encapsulated in PC framework, which acts as a nanoscale Faraday cage, and its excellent electrical conductivity prevents electrostatic charges from accumulating on the energetic material’s surface. The CA@PC composite energetic material has a CA content of 89.6%, and its electrostatic safety is nearly 30times that of pure CA(1.47 mJ compared to 0.05 mJ). CA@PC delivers an outstanding balance of safety and energy density compared to similar materials.
文摘During the Folin Ciocalteu (F-C) micro-assay for the determination of phenolics in the presence of methanol, fine solids can form. In a previous paper, we hypothesized that the interference from alcohol on the F-C reaction can be minimized depending on the particular procedure used to reach the alkalinity condition. In order to demonstrate our hypothesis we studied, by spectrophotometrically monitoring, the time-behaviour of the reactions carried out in the presence of different methanol concentrations at the same alkalinity condition from two protocols. The results showed that the interfering effect of methanol on the F-C micro-method can be affect and even prevented depending on working conditions. In particular, the formation of fine solids can be delayed, slowed down and prevented depending on the initial carbonate concentration used. We have explained why the initial carbonate concentration, used to reach the final alkalinity condition, plays an important role in the F-C reaction carried out in the presence of methanol. Moreover, the results from real-time monitoring showed that, differently from traditional F-C procedure, our procedure allows us to carry out the F-C micro method in the presence of 6% methanol, as an extreme concentration, reading the absorbance at real time 24 min. The real-time monitoring of absorbance can be considered as a useful means to explore the effect of other parameters on precipitate formation caused by the presence of methanol in the F-C reaction.