The carbon deposition behavior on nickel particles was observed within the temperature range from 400 to 800°C in a pure methane atmosphere. The topography, properties, and molecular structure of the deposited ca...The carbon deposition behavior on nickel particles was observed within the temperature range from 400 to 800°C in a pure methane atmosphere. The topography, properties, and molecular structure of the deposited carbon were investigated using field-emission scanning electron microscopy (FESEM), temperature-programmed oxidation (TPO) technology, X-ray diffraction (XRD), and Raman spectroscopy. The deposited carbon is present in the form of a film at 400-450°C, as fibers at 500-600°C, and as particles at 650-800°C. In addition, the structure of the deposited carbon becomes more ordered at higher temperatures because both the TPO peak temperature of deposited carbon and the Raman shift of the G band increase with the increase in experimental temperature, whereas the intensity ratio between the D bands and the G band decreases. An interesting observation is that the carbon deposition rate is suppressed in the medium-temperature range (M-T range) and the corresponding kinetic mechanism changes. Correspondingly, the FWHM of the G and D1 bands in the Raman spectrum reaches a maximum and the intensities of the D2, D3, and D4 bands decrease to low limits in the M-T range. These results indicate that carbon structure parameters exhibit two different tendencies with respect to varying temperature. Both of the two group parameters change dramatically as a peak function with increasing reaction temperature within the M-T range.展开更多
a-C:F films are deposited by microwave electron cyclotron resonance (ECR)plasma chemical vapor deposition (CVD) using trifluoromethane (CHF3) and benzene (C6H6) as source gases at different microwave powers. The radic...a-C:F films are deposited by microwave electron cyclotron resonance (ECR)plasma chemical vapor deposition (CVD) using trifluoromethane (CHF3) and benzene (C6H6) as source gases at different microwave powers. The radicals in plasma originating from source gases dissociation are analyzed by relative irradiance measurement. The bonding configurations and binding state of a-C:F films are measured with Fourier-transformed infrared spectrometer (FTIR) and x-ray photoelectron spectroscopy (XPS). The results show that a-C:F films are mainly composed of CF radical at lower powers but of CF2 radical at higher powers. The deposition of films is related to the radicals generated in plasma and the main bonding configurations are dependent on the ratio of CF to CF2 radicals in films.展开更多
In the present study,two Ni/YSZ anodes with different volume ratios of Ni and YSZ,30:70 and 45:55 vol%,are operated in dry methane under open circuit and polarized conditions.Three-dimensional(3D)Ni/YSZ microstructure...In the present study,two Ni/YSZ anodes with different volume ratios of Ni and YSZ,30:70 and 45:55 vol%,are operated in dry methane under open circuit and polarized conditions.Three-dimensional(3D)Ni/YSZ microstructures after carbon deposition are reconstructed by the focused ion beam-scanning electron microscopy(FIB-SEM)with the help of machine learning segmentation.From the reconstructed mircostructures,volume fraction,connectivity,three phase boundary(TPB)density,and tortuosity are quantified.In addition,local carbon microstructures are quantitatively reconstructed,and the effect of polarization on carbon morphology is investigated.It is demonstrated that Ni surface in the vicinity of active TPB near the electrolyte is free from carbon formation,while remaining Ni surface at some distances from TPB exhibits severe carbon deposition.In average,total amount of carbon deposition is larger near the electrolyte.These observations imply complex interplay between the electrochemical steam generation and methane cracking on Ni surface which take place very locally near the active TPB.展开更多
Survey and novel research data are used in the present study to classify/identify the lithological type of Verey age reservoirs’rocks.It is shown how the use of X-ray tomography can clarify the degree of heterogeneit...Survey and novel research data are used in the present study to classify/identify the lithological type of Verey age reservoirs’rocks.It is shown how the use of X-ray tomography can clarify the degree of heterogeneity,porosity and permeability of these rocks.These data are then used to elaborate a model of hydraulic fracturing.The resulting software can take into account the properties of proppant and breakdown fluid,thermal reservoir conditions,oil properties,well design data and even the filtration and elastic-mechanical properties of the rocks.Calculations of hydraulic fracturing crack formation are carried out and the results are compared with the data on hydraulic fracturing crack at standard conditions.Significant differences in crack formation in standard and lithotype models are determined.It is shown that the average width of the crack development for the lithotype model is 2.3 times higher than that for the standard model.Moreover,the coverage of crack development in height for the lithotype model is almost 2 times less than that for the standard model.The estimated fracture half-length for the lithotype model is 13.3%less than that of for the standard model.A higher dimensionless fracture conductivity is also obtained for the lithotype model.It is concluded that the proposed approach can increase the reliability of hydraulic fracturing crack models.展开更多
In order to avoid the formation ofηphase(W_(6)Co_(6)C or W_(3)Co_(3)C)that adversely affects the sintering process and its products in the preparation process of ultra-fine WC-Co powder,a technical route of prereduct...In order to avoid the formation ofηphase(W_(6)Co_(6)C or W_(3)Co_(3)C)that adversely affects the sintering process and its products in the preparation process of ultra-fine WC-Co powder,a technical route of prereduction of WO_(3)-Co_(3)O_(4)to WO_(2)-Co and then deep reduction carbonization to WC-Co powder has been proposed.This study mainly investigates the influence of gas partial pressure on the pre-reduction process of WO_(3)-Co_(3)O_(4)under a mixed atmosphere of H_(2)-C_(2)H_(4)-Ar at 600℃and establishes the kinetic equations of pre-reduction and carbon evolution.The results indicate that increasing the partial pressure of hydrogen is conducive to the rapid and complete conversion of WO_(3) to WO_(2).High carbon content can be generated by the deposition of C_(2)H_(4),and it hinders the diffusion of the reducing gas;WO_(3)still cannot be completely reduced to WO_(2)as the partial pressure of C_(2)H_(4) increases to 60%.For the carbon evolution of C_(2)H_(4),the carbon amount is positively related to the H_(2)partial pressure,but it shows the highest amount and evolution rate when the ethylene partial pressure is 20%.Based on the reduction rate curves of WO_(3) and carbon evolution rate curves of C_(2)H_(4),the rate equations of pre-reduction and carbon evolution of WO_(3)-Co_(3)O_(4)system at 600℃are established.The pre-reduction reaction belongs to the first-order reaction,and its equation is expressed as follows:r=-(dw_(WO_(3)))/dt=(9±0.15)×10^(-2)×P_(H_(2))^(0.44)P_(C_(2)H_(4))&(0.57)The carbon deposition rate equation of C_(2)H_(4) can be expressed as follows:r=-(dc_C)/dt=r_f-r_b≌7.35×10^(-2)×P_(C_(2)H_(4))^(0.31)展开更多
A series of model catalysts were obtained by treating commercial fresh and spent catalysts unloaded from the factory with different methods, including green oil dipping, extraction and high-temperature regeneration;fi...A series of model catalysts were obtained by treating commercial fresh and spent catalysts unloaded from the factory with different methods, including green oil dipping, extraction and high-temperature regeneration;finally, the deactivation behavior of the commercial catalyst for acetylene hydrogenation were studied. The influence of various possible deactivation factors on the catalytic performance was elucidated via detailed structural characterization, surface composition analysis, and activity evaluation.The results showed that green oil, carbon deposit and sintering of active metal were the main reasons for deactivation, among which green oil and carbon deposit led to rapid deactivation, while the activity could be recovered after regeneration by high-temperature calcination. The sintering of active metal components was attributed to the high-temperature regeneration in hydrothermal conditions, which was slow but irreversible and accounted for permanent deactivation. Thus, optimizing the regeneration is expected to extend the service life of the commercial catalyst.展开更多
Thermodynamic analysis was applied to study combined partial oxidation and carbon dioxide reforming of methane in view of carbon formation. The equilibrium calculations employing the Gibbs energy minimization were per...Thermodynamic analysis was applied to study combined partial oxidation and carbon dioxide reforming of methane in view of carbon formation. The equilibrium calculations employing the Gibbs energy minimization were performed upon wide ranges of pressure (1-25 atm), temperature (600-1300 K), carbon dioxide to methane ratio (0-2) and oxygen to methane ratio (0-1). The thermodynamic results were compared with the results obtained over a Ru supported catalyst. The results revealed that by increasing the reaction pressure methane conversion decreased. Also it was found that the atmospheric pressure is the preferable pressure for both dry reforming and partial oxidation of methane and increasing the temperature caused increases in both activity of carbon and conversion of methane. The results clearly showed that the addition of O2 to the feed mixture could lead to a reduction of carbon deposition.展开更多
In the present work,an interconnected sandwich carbon/Si-SiO2/carbon nanospheres composite was prepared by template method and carbon thermal vapor deposition(TVD).The carbon conductive layer can not only efficientl...In the present work,an interconnected sandwich carbon/Si-SiO2/carbon nanospheres composite was prepared by template method and carbon thermal vapor deposition(TVD).The carbon conductive layer can not only efficiently improve the electronic conductivity of Si-based anode,but also play a key role in alleviating the negative effect from huge volume expansion over discharge/charge of Si-based anode.The resulting material delivered a reversible capacity of 1094 mAh/g,and exhibited excellent cycling stability.It kept a reversible capacity of 1050 mAh/g over 200 cycles with a capacity retention of 96%.展开更多
The catalytic performance of methane partial oxidation was investigated on Pd/CeO2-ZrO2 and Pd/α-Al2O3 catalysts.The catalysts were characterized by XRD,Raman spectra,and TG-DTA techniques.The results show that CeO2-...The catalytic performance of methane partial oxidation was investigated on Pd/CeO2-ZrO2 and Pd/α-Al2O3 catalysts.The catalysts were characterized by XRD,Raman spectra,and TG-DTA techniques.The results show that CeO2-ZrO2 support is more advantageous for the catalytic activity and stability of catalysts compared to α-Al2O3.TG-DTA and Raman spectra results indicated that carbon deposited on the catalysts was in the form of graphite,which is the main reason for the deactivation of catalysts after a 24-hour reaction.Moreover,CeO2-ZrO2 had positive effect on inhibiting carbon deposition.展开更多
Carbon deposits were formed on the reactor wall during plasma pyrolysis of the Xinjiang candle coal in our V-style plasma pyrolysis pilot-plant. The carbon deposits were studied using a scanning electronic microscope ...Carbon deposits were formed on the reactor wall during plasma pyrolysis of the Xinjiang candle coal in our V-style plasma pyrolysis pilot-plant. The carbon deposits were studied using a scanning electronic microscope (SEM) and the X-ray diffraction (XRD) method. It was found that carbon deposits located at different parts in the reactor exhibited different microscopic patterns. The formation mechanism of the carbon deposits was deduced. The downward increase in the graphitization degree of the carbon deposits was found and interpreted.展开更多
In this topic, we first discussed the requirement and performance of supercapacitors using carbon nanotubes (CNTs) as the electrode, including specific surface area, purity and cost. Then we reviewed the preparation...In this topic, we first discussed the requirement and performance of supercapacitors using carbon nanotubes (CNTs) as the electrode, including specific surface area, purity and cost. Then we reviewed the preparation technique of single wailed CNTs (SWNTs) in relatively large scale by chemical vapor deposition method. Its catalysis on the decomposition of methane and other carbon source, the reactor type and the process control strategies were discussed. Special focus was concentrated on how to increase the yield, selectivity, and purity of SWNTs and how to inhibit the formation of impurities, including amorphous carbon, multiwalled CNTs and the carbon encapsulated metal particles, since these impurities seriously influenced the performance of SWNTs in supercapacitors. Wish it be helpful to further decrease its product cost and for the commercial use in supercapacitors.展开更多
To improve the‘detonation-supporting’performance of fuel-rich catalytic combustion products,DBD plasma,stimulated by adjustable nanosecond pulse power supply,was used to further regulate the components and concentra...To improve the‘detonation-supporting’performance of fuel-rich catalytic combustion products,DBD plasma,stimulated by adjustable nanosecond pulse power supply,was used to further regulate the components and concentrations of the hydrocarbon blends.In this paper,the parameters including load voltage,frequency,rising(falling)edge,pulse width and feeding flow rate were changed respectively,and the corresponding concentration and proportion change of the components in blend gas were investigated.According to the experiment result,it was found that when the discharge frequency is low,the plasma mainly promotes the transformation of light gaseous substances,while it mainly promotes the conversion to heavy hydrocarbons when the frequency is larger.Increasing load voltage will strengthen this trend.The controlling and reforming effect of plasma on the blend gas will decrease with the increase of voltage rising(falling)edge and the feeding flow rate.The regulation effect will be strengthened with the increase of pulse width under 200 ns.With the increase of discharge intensity,the‘carbon’settles on the walls of the reactor,which will change the dielectric constant,leading to the loss of control of the discharge.展开更多
Objective The Yubei area is located in the mid-east Maigaiti slope of southwestern Tarim Basin, China, with an exploration history of several years. Recent exploration has preliminarily indicated that the Ordovician ...Objective The Yubei area is located in the mid-east Maigaiti slope of southwestern Tarim Basin, China, with an exploration history of several years. Recent exploration has preliminarily indicated that the Ordovician carbonate formations in this area have some oil and gas potential. Carbonate microfacies provides material basis for reservoir development, seal formation and hydrocarbon generation. Therefore, this work utilized the standard microfacies (SMF) types to study the microfacies of the Ordovician formations in the Yubei area in order to provide theoretical basis for the next exploration.展开更多
The over-consumption of fossil fuels resulted in the large quantity emission of carbon dioxide (CO2), which was the main reason for the climate change and more extreme weathers. Hence, it is extremely pressing to ex...The over-consumption of fossil fuels resulted in the large quantity emission of carbon dioxide (CO2), which was the main reason for the climate change and more extreme weathers. Hence, it is extremely pressing to ex- plore efficient and sustainable approaches for the carbon-neutral pathway of CO2 utilization and recycling. In our recent works with this context, we developed successfully a novel "chemical vapor deposition integrated process (CVD-IP)" technology to converting robustly CO2 into the value-added solid-form carbon materials, The monometallic FeNi0-Al2O3 (FNi0) and bimetallic FeNix-Al2O3 (FNi2, FNi4, FNi8 and FNi20) samples were synthesized and effective for this new approach. The catalyst labeled FNi8 gave the better performance, exhibited the single pass solid carbon yield of 30%. These results illustrated alternative promising cases for the CO2 capture utilization storage (CCUS), by means of the CO2 catalytic conversion into the solid-form nano carbon materials.展开更多
Newly-acquired seismic data reveal widespread carbonate deposits covering a large part of the northwestern South China Sea margin.Three carbonate platforms are identified to have developed on the topographic highs inh...Newly-acquired seismic data reveal widespread carbonate deposits covering a large part of the northwestern South China Sea margin.Three carbonate platforms are identified to have developed on the topographic highs inherited from tectonic deformation and volcanic accretion.Across the carbonate platforms,the Miocene strata are characterized by high-amplitude seismic reflections and distinct platform architecture that overlaps older strata.The Guangle and Xisha carbonate platforms grew on faulted blocks due to South China Sea continental rifting,while the Zhongjian carbonate platform developed on a structural high induced by early Miocene volcanism.During the late Miocene,partial drowning resulted in the inhibition of platform growth,eventual platform drowning and termination of most carbonate deposition.The drowning of the Guangle and Zhongjian carbonate platforms is shown by the supply of siliciclastic sediments during the late Miocene and seems to be closely linked to late Neogene volcanic activity,whilst the drowning of the Xisha carbonate platform is primarily related to relative eustatic changes.Our results imply that tectonic activity,volcanism and eustasy are the dominant controls on the evolution of carbonate platforms on the northwestern margin of the South China Sea.展开更多
Cobalt ferrite nanoparticles(CFNPs) were prepared via a reverse micelle method. The CFNPs were subsequently coated with carbon shells by means of thermal chemical vapor deposition(TCVD). In this process, acetylene...Cobalt ferrite nanoparticles(CFNPs) were prepared via a reverse micelle method. The CFNPs were subsequently coated with carbon shells by means of thermal chemical vapor deposition(TCVD). In this process, acetylene gas(C2H2) was used as a carbon source and the coating was carried out for 1, 2, or 3 h at 750℃. The Ar/C2H2 ratio was 10:1. Heating during the TCVD process resulted in a NP core size that approached 30 nm; the thickness of the shell was less than 10 nm. The composition, structure, and morphology of the fabricated composites were characterized using X-ray diffraction, simultaneous thermal analysis, transmission electron microscopy, high-resolution transmission electron microscopy, and selected-area diffraction. A vibrating sample magnetometer was used to survey the samples' magnetic properties. The deposited carbon shell substantially affected the growth and magnetic properties of the CFNPs. Micro-Raman spectroscopy was used to study the carbon coating and revealed that the deposited carbon comprised graphite, multiwalled carbon nanotubes, and diamond-like carbon. With an increase in coating time, the intensity ratio between the amorphous and ordered peaks in the Raman spectra decreased, which indicated an increase in crystallite size.展开更多
Objective The Sachakou Pb-Zn polymetallic deposit is located in Hetian County, Xinjiang (geographical coordinates of E78° 57' 54.30"-78°59' 53.63", N34° 39' 27.50"-34° 40' 57.21"). It be...Objective The Sachakou Pb-Zn polymetallic deposit is located in Hetian County, Xinjiang (geographical coordinates of E78° 57' 54.30"-78°59' 53.63", N34° 39' 27.50"-34° 40' 57.21"). It belongs to the West Kunlun orogenic belt on the northwest edge of the Qinghai-Tibet Plateau and is connected to the Sanjiang orogenic belt to the south (Spurlin et al., 2005). In recent years, a series of Pb-Zn mineralized spots and deposits have been discovered in this area one after another, which is called the Huoshaoyun ore concentration area. Among them, the Sachakou Pb-Zn deposit has reserves up to140 Mt, which has reached a large scale. However, the study on the genesis of deposits in this area has only just begun. This work studied the genesis ofthis Pb-Zn deposit in order to provide new ideas for the genesis of regional deposits and regional prospecting.展开更多
A new method of fabricating C/C composite materials, namely electric heating CVD method, was used, which electrified the carbon fiber directly by using the conductivity of itself. Acetylene was used as the carbon sour...A new method of fabricating C/C composite materials, namely electric heating CVD method, was used, which electrified the carbon fiber directly by using the conductivity of itself. Acetylene was used as the carbon source with nitrogen as dilution gas, and the pyrolytic carbon started to deposit on the carbon fiber surface when the deposition temperature was reached. The morphology of pyrolytic carbon was characterized by SEM, and the surface properties of carbon fibers before and after CVD were characterized by Raman spectroscopy. The experimental results show that the electric heating method is a novel method to fabricate C/C composite materials, which can form a dense C/C composite material in a short time. The order degree and the average crystallite size of the carbon fiber surface were decreased after the experiment.展开更多
ZrO 2-Al 2O 3 composite oxides and supported Ni catalysts were prepared, and characterized by N 2 adsorption /desorption, X-ray diffraction(XRD) an d X-ray photoelectron spectroscopy(XPS) techniques. The catalytic...ZrO 2-Al 2O 3 composite oxides and supported Ni catalysts were prepared, and characterized by N 2 adsorption /desorption, X-ray diffraction(XRD) an d X-ray photoelectron spectroscopy(XPS) techniques. The catalytic performance and carbon deposition was also investigated. This mesoporous composite oxide is shown to be a promising catalyst support. An increase in the catalytic activity and stability of methane and carbon dioxide reforming reaction was resulted from the zirconia addition, especially at 5wt% ZrO 2 content. The Ni catalyst supported ZrO 2-Al 2O 3 has a strong resistance to sintering and the carbon deposition in a relatively long-term reaction.展开更多
基金financially supported by the National Program on Key Basic Research Project of China(No.2012CB215405)the China Postdoctoral Science Foundation(No.2015M570036)the National Natural Science Foundation of China(No.51174022)
文摘The carbon deposition behavior on nickel particles was observed within the temperature range from 400 to 800°C in a pure methane atmosphere. The topography, properties, and molecular structure of the deposited carbon were investigated using field-emission scanning electron microscopy (FESEM), temperature-programmed oxidation (TPO) technology, X-ray diffraction (XRD), and Raman spectroscopy. The deposited carbon is present in the form of a film at 400-450°C, as fibers at 500-600°C, and as particles at 650-800°C. In addition, the structure of the deposited carbon becomes more ordered at higher temperatures because both the TPO peak temperature of deposited carbon and the Raman shift of the G band increase with the increase in experimental temperature, whereas the intensity ratio between the D bands and the G band decreases. An interesting observation is that the carbon deposition rate is suppressed in the medium-temperature range (M-T range) and the corresponding kinetic mechanism changes. Correspondingly, the FWHM of the G and D1 bands in the Raman spectrum reaches a maximum and the intensities of the D2, D3, and D4 bands decrease to low limits in the M-T range. These results indicate that carbon structure parameters exhibit two different tendencies with respect to varying temperature. Both of the two group parameters change dramatically as a peak function with increasing reaction temperature within the M-T range.
文摘a-C:F films are deposited by microwave electron cyclotron resonance (ECR)plasma chemical vapor deposition (CVD) using trifluoromethane (CHF3) and benzene (C6H6) as source gases at different microwave powers. The radicals in plasma originating from source gases dissociation are analyzed by relative irradiance measurement. The bonding configurations and binding state of a-C:F films are measured with Fourier-transformed infrared spectrometer (FTIR) and x-ray photoelectron spectroscopy (XPS). The results show that a-C:F films are mainly composed of CF radical at lower powers but of CF2 radical at higher powers. The deposition of films is related to the radicals generated in plasma and the main bonding configurations are dependent on the ratio of CF to CF2 radicals in films.
基金partly supported by the New Energy and Industrial Technology Development Organization(NEDO)by the Japan Society for the Promotion of Science KAKENHI(21K14090)+3 种基金the National Key R&D Program of China(2019YFE0122000)the Scientific Research Foundation of Graduate School of Southeast University(YBPY2106)the China Scholarship Councilby the Advanced Research Infrastructure for Materials and Nanotechnology in Japan(ARIM Japan)sponsored by the Ministry of Education,Culture,Sport,Science and Technology(MEXT),Japan。
文摘In the present study,two Ni/YSZ anodes with different volume ratios of Ni and YSZ,30:70 and 45:55 vol%,are operated in dry methane under open circuit and polarized conditions.Three-dimensional(3D)Ni/YSZ microstructures after carbon deposition are reconstructed by the focused ion beam-scanning electron microscopy(FIB-SEM)with the help of machine learning segmentation.From the reconstructed mircostructures,volume fraction,connectivity,three phase boundary(TPB)density,and tortuosity are quantified.In addition,local carbon microstructures are quantitatively reconstructed,and the effect of polarization on carbon morphology is investigated.It is demonstrated that Ni surface in the vicinity of active TPB near the electrolyte is free from carbon formation,while remaining Ni surface at some distances from TPB exhibits severe carbon deposition.In average,total amount of carbon deposition is larger near the electrolyte.These observations imply complex interplay between the electrochemical steam generation and methane cracking on Ni surface which take place very locally near the active TPB.
基金The research was carried out within the framework of the grant for state support of leading scientific schools of the Russian Federation(Grant No.NSh-1010.2022.1.5).
文摘Survey and novel research data are used in the present study to classify/identify the lithological type of Verey age reservoirs’rocks.It is shown how the use of X-ray tomography can clarify the degree of heterogeneity,porosity and permeability of these rocks.These data are then used to elaborate a model of hydraulic fracturing.The resulting software can take into account the properties of proppant and breakdown fluid,thermal reservoir conditions,oil properties,well design data and even the filtration and elastic-mechanical properties of the rocks.Calculations of hydraulic fracturing crack formation are carried out and the results are compared with the data on hydraulic fracturing crack at standard conditions.Significant differences in crack formation in standard and lithotype models are determined.It is shown that the average width of the crack development for the lithotype model is 2.3 times higher than that for the standard model.Moreover,the coverage of crack development in height for the lithotype model is almost 2 times less than that for the standard model.The estimated fracture half-length for the lithotype model is 13.3%less than that of for the standard model.A higher dimensionless fracture conductivity is also obtained for the lithotype model.It is concluded that the proposed approach can increase the reliability of hydraulic fracturing crack models.
基金the National Natural Science Foundation of China(22078326,21878305,21908227)。
文摘In order to avoid the formation ofηphase(W_(6)Co_(6)C or W_(3)Co_(3)C)that adversely affects the sintering process and its products in the preparation process of ultra-fine WC-Co powder,a technical route of prereduction of WO_(3)-Co_(3)O_(4)to WO_(2)-Co and then deep reduction carbonization to WC-Co powder has been proposed.This study mainly investigates the influence of gas partial pressure on the pre-reduction process of WO_(3)-Co_(3)O_(4)under a mixed atmosphere of H_(2)-C_(2)H_(4)-Ar at 600℃and establishes the kinetic equations of pre-reduction and carbon evolution.The results indicate that increasing the partial pressure of hydrogen is conducive to the rapid and complete conversion of WO_(3) to WO_(2).High carbon content can be generated by the deposition of C_(2)H_(4),and it hinders the diffusion of the reducing gas;WO_(3)still cannot be completely reduced to WO_(2)as the partial pressure of C_(2)H_(4) increases to 60%.For the carbon evolution of C_(2)H_(4),the carbon amount is positively related to the H_(2)partial pressure,but it shows the highest amount and evolution rate when the ethylene partial pressure is 20%.Based on the reduction rate curves of WO_(3) and carbon evolution rate curves of C_(2)H_(4),the rate equations of pre-reduction and carbon evolution of WO_(3)-Co_(3)O_(4)system at 600℃are established.The pre-reduction reaction belongs to the first-order reaction,and its equation is expressed as follows:r=-(dw_(WO_(3)))/dt=(9±0.15)×10^(-2)×P_(H_(2))^(0.44)P_(C_(2)H_(4))&(0.57)The carbon deposition rate equation of C_(2)H_(4) can be expressed as follows:r=-(dc_C)/dt=r_f-r_b≌7.35×10^(-2)×P_(C_(2)H_(4))^(0.31)
基金the financial support from the Sinopec Catalyst Co.Ltd.,China。
文摘A series of model catalysts were obtained by treating commercial fresh and spent catalysts unloaded from the factory with different methods, including green oil dipping, extraction and high-temperature regeneration;finally, the deactivation behavior of the commercial catalyst for acetylene hydrogenation were studied. The influence of various possible deactivation factors on the catalytic performance was elucidated via detailed structural characterization, surface composition analysis, and activity evaluation.The results showed that green oil, carbon deposit and sintering of active metal were the main reasons for deactivation, among which green oil and carbon deposit led to rapid deactivation, while the activity could be recovered after regeneration by high-temperature calcination. The sintering of active metal components was attributed to the high-temperature regeneration in hydrothermal conditions, which was slow but irreversible and accounted for permanent deactivation. Thus, optimizing the regeneration is expected to extend the service life of the commercial catalyst.
基金supported by the Key Project of Chinese National Programs for Fundamental Research and Development(973 Program 2005CB221204)the Natural Science Fund of China(20676087)
基金supported by University of Kashan(Grant No.158426/5)
文摘Thermodynamic analysis was applied to study combined partial oxidation and carbon dioxide reforming of methane in view of carbon formation. The equilibrium calculations employing the Gibbs energy minimization were performed upon wide ranges of pressure (1-25 atm), temperature (600-1300 K), carbon dioxide to methane ratio (0-2) and oxygen to methane ratio (0-1). The thermodynamic results were compared with the results obtained over a Ru supported catalyst. The results revealed that by increasing the reaction pressure methane conversion decreased. Also it was found that the atmospheric pressure is the preferable pressure for both dry reforming and partial oxidation of methane and increasing the temperature caused increases in both activity of carbon and conversion of methane. The results clearly showed that the addition of O2 to the feed mixture could lead to a reduction of carbon deposition.
基金supported by the State Key Basic Research Program of PRC(2011CB935903)the National Natural Science Foundation of China(No.20925312)Shanghai Science Technology Committee(13JC1407900)
文摘In the present work,an interconnected sandwich carbon/Si-SiO2/carbon nanospheres composite was prepared by template method and carbon thermal vapor deposition(TVD).The carbon conductive layer can not only efficiently improve the electronic conductivity of Si-based anode,but also play a key role in alleviating the negative effect from huge volume expansion over discharge/charge of Si-based anode.The resulting material delivered a reversible capacity of 1094 mAh/g,and exhibited excellent cycling stability.It kept a reversible capacity of 1050 mAh/g over 200 cycles with a capacity retention of 96%.
基金Project supported by the National‘973’Project(2004CB719503)Petro China(W050509-01-05)
文摘The catalytic performance of methane partial oxidation was investigated on Pd/CeO2-ZrO2 and Pd/α-Al2O3 catalysts.The catalysts were characterized by XRD,Raman spectra,and TG-DTA techniques.The results show that CeO2-ZrO2 support is more advantageous for the catalytic activity and stability of catalysts compared to α-Al2O3.TG-DTA and Raman spectra results indicated that carbon deposited on the catalysts was in the form of graphite,which is the main reason for the deactivation of catalysts after a 24-hour reaction.Moreover,CeO2-ZrO2 had positive effect on inhibiting carbon deposition.
文摘Carbon deposits were formed on the reactor wall during plasma pyrolysis of the Xinjiang candle coal in our V-style plasma pyrolysis pilot-plant. The carbon deposits were studied using a scanning electronic microscope (SEM) and the X-ray diffraction (XRD) method. It was found that carbon deposits located at different parts in the reactor exhibited different microscopic patterns. The formation mechanism of the carbon deposits was deduced. The downward increase in the graphitization degree of the carbon deposits was found and interpreted.
基金financially supported by the National Basic Research Program of China (2011CB932602)the NSFC Key Program (20736007,20736004)the Foundation of Tsinghua University (2011THZ08,new energy)
文摘In this topic, we first discussed the requirement and performance of supercapacitors using carbon nanotubes (CNTs) as the electrode, including specific surface area, purity and cost. Then we reviewed the preparation technique of single wailed CNTs (SWNTs) in relatively large scale by chemical vapor deposition method. Its catalysis on the decomposition of methane and other carbon source, the reactor type and the process control strategies were discussed. Special focus was concentrated on how to increase the yield, selectivity, and purity of SWNTs and how to inhibit the formation of impurities, including amorphous carbon, multiwalled CNTs and the carbon encapsulated metal particles, since these impurities seriously influenced the performance of SWNTs in supercapacitors. Wish it be helpful to further decrease its product cost and for the commercial use in supercapacitors.
基金supported by National Natural Science Foundation of China(Nos.91941105,91941301,51790511)。
文摘To improve the‘detonation-supporting’performance of fuel-rich catalytic combustion products,DBD plasma,stimulated by adjustable nanosecond pulse power supply,was used to further regulate the components and concentrations of the hydrocarbon blends.In this paper,the parameters including load voltage,frequency,rising(falling)edge,pulse width and feeding flow rate were changed respectively,and the corresponding concentration and proportion change of the components in blend gas were investigated.According to the experiment result,it was found that when the discharge frequency is low,the plasma mainly promotes the transformation of light gaseous substances,while it mainly promotes the conversion to heavy hydrocarbons when the frequency is larger.Increasing load voltage will strengthen this trend.The controlling and reforming effect of plasma on the blend gas will decrease with the increase of voltage rising(falling)edge and the feeding flow rate.The regulation effect will be strengthened with the increase of pulse width under 200 ns.With the increase of discharge intensity,the‘carbon’settles on the walls of the reactor,which will change the dielectric constant,leading to the loss of control of the discharge.
基金funded by the National Natural Science Foundation of China(grant No.41572117)Technological&Developmental Department of China Petroleum&Chemical Corporation(grants No.P13040 and P14128)China Geological Survey(grant No.DD20160175-1-1)
文摘Objective The Yubei area is located in the mid-east Maigaiti slope of southwestern Tarim Basin, China, with an exploration history of several years. Recent exploration has preliminarily indicated that the Ordovician carbonate formations in this area have some oil and gas potential. Carbonate microfacies provides material basis for reservoir development, seal formation and hydrocarbon generation. Therefore, this work utilized the standard microfacies (SMF) types to study the microfacies of the Ordovician formations in the Yubei area in order to provide theoretical basis for the next exploration.
基金support for this project from the National Natural Science Foundation of China (21476145)the National 973 Program of Ministry of Sciences and Technologies of China (2011CB201202)
文摘The over-consumption of fossil fuels resulted in the large quantity emission of carbon dioxide (CO2), which was the main reason for the climate change and more extreme weathers. Hence, it is extremely pressing to ex- plore efficient and sustainable approaches for the carbon-neutral pathway of CO2 utilization and recycling. In our recent works with this context, we developed successfully a novel "chemical vapor deposition integrated process (CVD-IP)" technology to converting robustly CO2 into the value-added solid-form carbon materials, The monometallic FeNi0-Al2O3 (FNi0) and bimetallic FeNix-Al2O3 (FNi2, FNi4, FNi8 and FNi20) samples were synthesized and effective for this new approach. The catalyst labeled FNi8 gave the better performance, exhibited the single pass solid carbon yield of 30%. These results illustrated alternative promising cases for the CO2 capture utilization storage (CCUS), by means of the CO2 catalytic conversion into the solid-form nano carbon materials.
基金funded by the National Science and Technology Major Project“The evaluations of deepwater oil and gas geological conditions and targets in Zhongjian area of the South China Sea”(No.2017ZX05026006)the CNPC Science and Technology Major Projects(No.2019A-1009&2019D4309)+1 种基金the Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDA13010101)National Natural Science Foundation of China(No.41706054)。
文摘Newly-acquired seismic data reveal widespread carbonate deposits covering a large part of the northwestern South China Sea margin.Three carbonate platforms are identified to have developed on the topographic highs inherited from tectonic deformation and volcanic accretion.Across the carbonate platforms,the Miocene strata are characterized by high-amplitude seismic reflections and distinct platform architecture that overlaps older strata.The Guangle and Xisha carbonate platforms grew on faulted blocks due to South China Sea continental rifting,while the Zhongjian carbonate platform developed on a structural high induced by early Miocene volcanism.During the late Miocene,partial drowning resulted in the inhibition of platform growth,eventual platform drowning and termination of most carbonate deposition.The drowning of the Guangle and Zhongjian carbonate platforms is shown by the supply of siliciclastic sediments during the late Miocene and seems to be closely linked to late Neogene volcanic activity,whilst the drowning of the Xisha carbonate platform is primarily related to relative eustatic changes.Our results imply that tectonic activity,volcanism and eustasy are the dominant controls on the evolution of carbonate platforms on the northwestern margin of the South China Sea.
文摘Cobalt ferrite nanoparticles(CFNPs) were prepared via a reverse micelle method. The CFNPs were subsequently coated with carbon shells by means of thermal chemical vapor deposition(TCVD). In this process, acetylene gas(C2H2) was used as a carbon source and the coating was carried out for 1, 2, or 3 h at 750℃. The Ar/C2H2 ratio was 10:1. Heating during the TCVD process resulted in a NP core size that approached 30 nm; the thickness of the shell was less than 10 nm. The composition, structure, and morphology of the fabricated composites were characterized using X-ray diffraction, simultaneous thermal analysis, transmission electron microscopy, high-resolution transmission electron microscopy, and selected-area diffraction. A vibrating sample magnetometer was used to survey the samples' magnetic properties. The deposited carbon shell substantially affected the growth and magnetic properties of the CFNPs. Micro-Raman spectroscopy was used to study the carbon coating and revealed that the deposited carbon comprised graphite, multiwalled carbon nanotubes, and diamond-like carbon. With an increase in coating time, the intensity ratio between the amorphous and ordered peaks in the Raman spectra decreased, which indicated an increase in crystallite size.
基金the 8th Geological Brigade of Aksu,Xinjiang, the Institute of Geology of the Chinese Academy of Geological Sciencesthe Beijing Research Institute of Uranium Geology,CNNC
文摘Objective The Sachakou Pb-Zn polymetallic deposit is located in Hetian County, Xinjiang (geographical coordinates of E78° 57' 54.30"-78°59' 53.63", N34° 39' 27.50"-34° 40' 57.21"). It belongs to the West Kunlun orogenic belt on the northwest edge of the Qinghai-Tibet Plateau and is connected to the Sanjiang orogenic belt to the south (Spurlin et al., 2005). In recent years, a series of Pb-Zn mineralized spots and deposits have been discovered in this area one after another, which is called the Huoshaoyun ore concentration area. Among them, the Sachakou Pb-Zn deposit has reserves up to140 Mt, which has reached a large scale. However, the study on the genesis of deposits in this area has only just begun. This work studied the genesis ofthis Pb-Zn deposit in order to provide new ideas for the genesis of regional deposits and regional prospecting.
基金Funded by the National Natural Science Foundation of China(51165006)
文摘A new method of fabricating C/C composite materials, namely electric heating CVD method, was used, which electrified the carbon fiber directly by using the conductivity of itself. Acetylene was used as the carbon source with nitrogen as dilution gas, and the pyrolytic carbon started to deposit on the carbon fiber surface when the deposition temperature was reached. The morphology of pyrolytic carbon was characterized by SEM, and the surface properties of carbon fibers before and after CVD were characterized by Raman spectroscopy. The experimental results show that the electric heating method is a novel method to fabricate C/C composite materials, which can form a dense C/C composite material in a short time. The order degree and the average crystallite size of the carbon fiber surface were decreased after the experiment.
文摘ZrO 2-Al 2O 3 composite oxides and supported Ni catalysts were prepared, and characterized by N 2 adsorption /desorption, X-ray diffraction(XRD) an d X-ray photoelectron spectroscopy(XPS) techniques. The catalytic performance and carbon deposition was also investigated. This mesoporous composite oxide is shown to be a promising catalyst support. An increase in the catalytic activity and stability of methane and carbon dioxide reforming reaction was resulted from the zirconia addition, especially at 5wt% ZrO 2 content. The Ni catalyst supported ZrO 2-Al 2O 3 has a strong resistance to sintering and the carbon deposition in a relatively long-term reaction.