This paper deals with thermodynamic chemical equilibrium analysis using the method of direct minimization of Gibbs free energy for all possible CH4 and CO2 reactions. The effects of CO2/CH4 feed ratio, reaction temper...This paper deals with thermodynamic chemical equilibrium analysis using the method of direct minimization of Gibbs free energy for all possible CH4 and CO2 reactions. The effects of CO2/CH4 feed ratio, reaction temperature, and system pressure on equilibrium composition, conversion, selectivity and yield were studied. In addition, carbon and no carbon formation regions were also considered at various reaction temperatures and CO2/CH4 feed ratios in the reaction system at equilibrium. It was found that the reaction temperature above 1100 K and CO2/CH4 ratio=1 were favourable for synthesis gas production with H2/CO ratio unity, while carbon dioxide oxidative coupling of methane (CO2 OCM) reaction to produce ethane and ethylene is less favourable thermodynamically. Numerical results indicated that the no carbon formation region was at temperatures above 1000 K and CO2/CH4 ratio larger than 1.展开更多
In this paper the effect of catalyst and carrier in electric field enhanced plasma on methane conversion into C2 hydrocarbons was investigated. Methane coupling reaction was studied in the system of continuous flow r...In this paper the effect of catalyst and carrier in electric field enhanced plasma on methane conversion into C2 hydrocarbons was investigated. Methane coupling reaction was studied in the system of continuous flow reactor on Ni, MoO3, MnO2 catalysts and different ZSM-5 carriers. The per pass conversion of methane can be as high as 22%, the selectivity of ethylene can be as high as 23.8%, of acetylene 60.8%, of ethane 5.4% and of total C2 hydrocarbons was more than 90%. ZSM-5-25 was the better carrier and MnO2 was the better active component. The efficiency of energy was as high as 7.81%.展开更多
Direct conversion of methane to C_2 hydrocarbons via cold plasma reactionwith catalysts has been studied at room temperature and atmospheric pressure. Methane can beconverted into C_2 hydrocarbons in different selecti...Direct conversion of methane to C_2 hydrocarbons via cold plasma reactionwith catalysts has been studied at room temperature and atmospheric pressure. Methane can beconverted into C_2 hydrocarbons in different selectivity depending on the form of the reactor, powerof plasma, flow rate of methane, ratio of N_2/CH_4 and nature of the catalysts. The selectivity toC_2 hydrocarbons can reach as high as 98.64%, and the conversion of methane as high as 60% and theyield of C_2 hydrocarbons as high as 50% are obtained. Coking can be minimized under the conditionsof: proper selection of the catalysts, appropriate high flow rate of inlet methane and suitableratio of N_2 to CH_4. The catalyst surface provides active sites for radical recombination.展开更多
The use of gas diffusion electrode(GDE)based flow cell can realize industrial-scale CO_(2) reduction reactions(CO_(2)RRs).Controlling local CO_(2) and CO intermediate diffusion plays a key role in CO_(2)RR toward mult...The use of gas diffusion electrode(GDE)based flow cell can realize industrial-scale CO_(2) reduction reactions(CO_(2)RRs).Controlling local CO_(2) and CO intermediate diffusion plays a key role in CO_(2)RR toward multi-carbon(C_(2+))products.In this work,local CO_(2) and CO intermediate diffusion through the catalyst layer(CL)was investigated for improving CO_(2)RR toward C_(2+)products.The gas permeability tests and finite element simulation results indicated CL can balance the CO_(2) gas diffusion and residence time of the CO intermediate,leading to a sufficient CO concentration with a suitable CO_(2)/H_(2)O supply for high C_(2+)products.As a result,an excellent selectivity of C_(2+)products~79%at a high current density of 400 mA·cm^(-2) could be obtained on the optimal 500 nm Cu CL(Cu500).This work provides a new insight into the optimization of CO_(2)/H_(2)O supply and local CO concentration by controlling CL for C_(2+)products in CO_(2)RR flow cell.展开更多
In the past two decades,research on C_(2)storage in coal seams and simultaneously enhanced coalbed methane recovery(ECBM)has attracted a lot of attention due to its win–win effect between greenhouse gas(C_(2))emissio...In the past two decades,research on C_(2)storage in coal seams and simultaneously enhanced coalbed methane recovery(ECBM)has attracted a lot of attention due to its win–win effect between greenhouse gas(C_(2))emission reduction and coalbed methane recovery enhancement.This paper presents an overview on the current status of research on C_(2)-ECBM in the past two decades,which involves C_(2)storage capacity evaluations,laboratory investigations,modelings and pilot tests.The current status shows that we have made great progress in the ECBM technology study,especially in the understanding of the ECBM mechanisms.However,there still have many technical challenges,such as the definition of unmineable coal seams for C_(2)storage capacity evaluation and storage site characterization,methods for C_(2)injectivity enhancement,etc.The low injectivity of coal seams and injectivity loss with C_(2)injection are the major technique challenges of ECBM.We also search several ways to promote the advancement of ECBM technology in the present stage,such as integrating ECBM with hydraulic fracturing,using a gas mixture instead of pure C_(2)for injection into coal seams and the application of ECBM to underground coal mines.展开更多
The infrared emission spectra of methane, H, CH' and C_2 hydrocarbons in natural gas were measured. The processes of methane decomposition and formation of C_2 hydrocarbons were studied. The experiment shows that ...The infrared emission spectra of methane, H, CH' and C_2 hydrocarbons in natural gas were measured. The processes of methane decomposition and formation of C_2 hydrocarbons were studied. The experiment shows that methane decomposition can be divided into three periods as the reaction proceeds. In the first period, a large number of free radicals were formed. While in the last period, the formation of C_2 hydrocarbons and the decrease of free radicals were observed. The time and conditions of methane decomposition and formation of C_2 hydrocarbons are different.展开更多
Nitrogen-rich porous organic polymers have shown great potentials in gas adsorption/separation,photocatalysis,electrochemistry,sensing and so on.Herein,1,2,3-triazole functionalized triazine-based porous organic polym...Nitrogen-rich porous organic polymers have shown great potentials in gas adsorption/separation,photocatalysis,electrochemistry,sensing and so on.Herein,1,2,3-triazole functionalized triazine-based porous organic polymers(TT-POPs)have been synthesized by the copper-catalyzed azide-alkyne cycloaddition(Cu-AAC)polymerization reactions of 1,3,5-tris(4-azidophenyl)-triazine with 1,4-diacetylene benzene and 1,3,5-triacetylenebenzene,respectively.The characterizations of N2 adsorption at 77 K show TTPOPs possess permanent porosity with BET surface areas of 666 m^(2)·g^(-1)(TT-POP-1)and 406 m^(2)·g^(-1)(TT-POP-2).The adsorption capacities of TT-POPs for CO_(2),CH4,C2H2 and C2H4,as well as the selective separation abilities of CO_(2)/N2,CO_(2)/CH_(4),C_(2)H_(2)/CH_(4) and C_(2)H_(4)/CH_(4) were evaluated.The gas selective separation ratio of TT-POPs was calculated by the ideal adsorbed solution theory(IAST)method,wherein the selective separation ratios of C_(2)H_(2)/CH_(4) and C_(2)H_(4)/CH_(4) of TT-POP-2 was 48.4 and 13.6(298 K,0.1 MPa),which is comparable to other adsorbents(5.6–120.6 for C_(2)H_(2)/CH_(4),10–26 for C_(2)H_(4)/CH_(4)).This work shows that the 1,2,3-triazole functionalized triazine-based porous organic polymer has a good application prospect in natural gas purification.展开更多
The paper is devoted to the two-phase flow simulation.The gas-condensate mixture flow in a horizontal pipe under high pressure is considered.The influence of the equation of state(EOS)choice for mixture properties mod...The paper is devoted to the two-phase flow simulation.The gas-condensate mixture flow in a horizontal pipe under high pressure is considered.The influence of the equation of state(EOS)choice for mixture properties modelling on the flow regime calculation results is studied for gas with high content of methane homologues.An analytical overview of the methods to predict the flow pattern is provided.Based on this analysis,two techniques are selected.For these techniques,values of density and viscosity for each phase are required.Density calculation for the gas phase is performed with Van der Waals based EOS.The propriate EOS is selected based on studies of calculation errors for test mixtures.Calculation of liquid phase density is done by means of Patela-Teja and Guo-Du equations,two different models are considered for viscosity estimation.The flow patterns of gas-condensate mixture in a range of temperatures and pressures are calculated and verified via probability map.The results of study allow to recommend the Brusilovsky EOS for calculation of densities for similar gas mixtures and make more rigorous flow regime evaluation.The probability map shows that for the chosen composition and parameters of media the flow pattern is mostly transitional between segregated and annular independent from EOS.展开更多
The experiments are carried out in the system of continuous flow reactors with dielectric-barrier discharge (DBD) for studies on the conversion of natural gas to C2 hydrocarbons through plasma catalysis under the atmo...The experiments are carried out in the system of continuous flow reactors with dielectric-barrier discharge (DBD) for studies on the conversion of natural gas to C2 hydrocarbons through plasma catalysis under the atmosphere pressure and room temperature. The influence of discharge frequency, structure of electrode, discharge voltage, number of electrode, ratio of H2/CH4, flow rate and catalyst on conversion of methane and selectivity of C2 hydrocarbons are investigated. At the same time, the reaction process is investigated. Higher conversion of methane and selectivity of C2 hydrocarbons are achieved and deposited carbons are eliminated by proper choice of parameters. The appropriate operation parameters in dielectric-barrier discharge plasma field are that the supply voltage is 20-40 kV (8.4-40 W), the frequency of power supply is 20 kHz, the structure of (b) electrode is suitable, and the flow of methane is 20-60 ml · min-1. The conversion of methane can reach 45%, the selectivity of C2 hydrocarbons展开更多
Ti_(3)C_(2)T_(x),which is a novel two-dimensional(2 D)material,has received enormous interest in the field of sensor technology due to its large surface area,excellent electrical conductivity,and abundant active surfa...Ti_(3)C_(2)T_(x),which is a novel two-dimensional(2 D)material,has received enormous interest in the field of sensor technology due to its large surface area,excellent electrical conductivity,and abundant active surface sites.In recent years,several Ti_(3)C_(2)T_(x)-based gases and humidity sensors have been developed and reported.In this review,we focus on the latest applications of Ti_(3)C_(2)T_(x)-based nanomaterials in gas and humidity sensors.First,the synthesis of Ti_(3)C_(2)T_(x) from the dangerous fluorine-containing etching process to the safe fluorine-free preparation method was discussed,and the structures of the Ti_(3)C_(2)T_(x) controlled by different delamination methods were also outlined.Subsequently,the functionalization of pristine Ti_(3)C_(2)T_(x) and composite strategies for enhancing its gas and humidity sensing performance were reviewed.In addition,the gas and humidity sensing mechanisms of sensors based on Ti_(3)C_(2)T_(x) were also summarized.Finally,the challenges and opportunities for the use of Ti_(3)C_(2)T_(x) gas and humidity sensors were discussed to provide guidance on the promising potential of Ti_(3)C_(2)T_(x) in this field.展开更多
Separation of C_(2) gases(C_(2)H_(2)/C_(2)H_(4),C_(2)H_(6)/C_(2)H_(4) and C_(2)H_(2)/CO_(2))mixtures is one of the most important and energy-demanding processes in chemical industry.Traditional separation methods(fine...Separation of C_(2) gases(C_(2)H_(2)/C_(2)H_(4),C_(2)H_(6)/C_(2)H_(4) and C_(2)H_(2)/CO_(2))mixtures is one of the most important and energy-demanding processes in chemical industry.Traditional separation methods(fine distillation separation and selective catalytic hydrogenation separation)have the shortages of high energy consumption and inefficient use of resources,affecting the achievement of peak carbon dioxide emissions and carbon neutrality targets.Separation based on adsorption is considered as one of the best ways to achieve low-energy separations.Therefore,it is of great importance to synthesize materials that enable the effective separation and purification of C_(2) gases under mild conditions.As an emerging class of porous materials,metal-organic frameworks(MOFs)show great promise in the field of gas separation and purification due to their ultra-high specific surface area,easily modifiable pore surfaces,structural designability and functionalization.Herein,we summarize recent research advances by use of MOFs sorbents for the separation and purification of C_(2) gases,including C_(2)H_(2)/C_(2)H_(4),C_(2)H_(6)/C_(2)H_(4) and C_(2)H_(2)/CO_(2).Relationship between structures and separation mechanism is also explored.Furthermore,challenges and possible research directions related to the further exploration are also discussed.展开更多
By using the methods of hydrocarbon generation kinetics and carbon isotope kinetics, combined with geological background of natural gas pool formation, the generation and accumulation of natural gas from Yinan 2 gas p...By using the methods of hydrocarbon generation kinetics and carbon isotope kinetics, combined with geological background of natural gas pool formation, the generation and accumulation of natural gas from Yinan 2 gas pool was studied in Kuqa Depression of the Tarim Basin. Natural gas of Yinan 2 gas pool is mainly derived from Middle and Lower Jurassic coal-bearing source rocks, and generally belongs to long time-accumulated gas. It is suggested that Yinan 2 gas is chiefly accumulated in the last 5 Ma, its Ro ranges from 1.25% to 1.95%, and the loss rate of natural gas is about 25%-30%. This work not only complements and reduces the deficiency of formation model of natural gas pools which traditionally depends on the matching relationships between source rock, reservoir, cap rock, and trap, but also is a useful reference in the study of other gas pools.展开更多
Acetone,as widely used reagents in industry and laboratories,are extremely harmful to the human.So the detection of acetone gas concentrations and leaks in special environments at room temperature is essential.Herein,...Acetone,as widely used reagents in industry and laboratories,are extremely harmful to the human.So the detection of acetone gas concentrations and leaks in special environments at room temperature is essential.Herein,the nanocomposite combining SnO-SnO_(2)(p-n junction)and Ti_(3)C_(2)T_(x) MXene was successfully synthesized by a one-step hydrothermal method.Because of the existence of a small amount of oxygen during the hydrothermal conditions,part of the p-type SnO was oxidized to n-type SnO_(2),forming in-situ p-n junctions on the surface of Sn O.The hamburger-like SnO-SnO_(2)/Ti_(3)C_(2)T_(x) sensor exhibited improved acetone gas sensing response of 12.1(R_(g)/R_(a))at room temperature,which were nearly 11 and 4 times higher than those of pristine Ti_(3)C_(2)T_(x) and pristine SnO-SnO_(2),respectively.Moreover,it expressed a short recovery time(9 s)and outstanding reproducibility.Because of the different work functions,the Schottky barrier was formed between the SnO and the Ti_(3)C_(2)T_(x) nanosheets,acting as a hole accumulation layer(HALs)between Ti_(3)C_(2)T_(x) and tin oxides.Herein,the sensing mechanism based on the formation of hetero-junctions and high conductivity of the metallic phase of Ti_(3)C_(2)T_(x) MXene in SnO-SnO_(2)/Ti_(3)C_(2)T_(x) sensors was discussed in detail.展开更多
With the disruptive carbon cycle being blamed for global warming,the plausible electrocatalytic CO_(2)reduction reaction(CO_(2)RR)to form valuable C_(2+)hydrocarbons and feedstock is becoming a hot topic.Cu-based elec...With the disruptive carbon cycle being blamed for global warming,the plausible electrocatalytic CO_(2)reduction reaction(CO_(2)RR)to form valuable C_(2+)hydrocarbons and feedstock is becoming a hot topic.Cu-based electrocatalysts have been proven to be excellent CO_(2)RR alternatives for high energy value-added products in this regard.However,the selectivity of CO_(2)RR to form C_(2+)products via Cu-based catalysts suffers from a high overpotential,slow reaction kinetics,and low selectivity.This review attempts to discuss various cutting-edge strategies for understanding catalytic design such as Cu-based catalyst surface engineering,tuning Cu bandgap via alloying,nanocatalysis,and the effect of the electrolyte and pH on catalyst morphology.The most recent advances in in situ spectroscopy and computational techniques are summarized to fully comprehend reaction mechanisms,structural transformation/degradation mechanisms,and crystal facet loss with subsequent effects on catalyst activity.Furthermore,approaches for tuning Cu interactions are discussed from four key perspectives:single-atom catalysts,interfacial engineering,metal-organic frameworks,and polymer-incorporated materials,which provide new insights into the selectivity of C_(2+)products.Finally,major challenges are outlined,and potential prospects for the rational design of catalysts for robust CO_(2)RR are proposed.The integration of catalytic design with mechanistic understanding is a step forward in the promising advancement of CO_(2)RR technology for industrial applications.展开更多
P-xylene(p-C_(8)H_(10))is extremely harmful and dangerous to human health due to high toxicity and strong carcinogenicity.Exploring sensitive material to effectively detect p-xylene is of importance.In this paper,pero...P-xylene(p-C_(8)H_(10))is extremely harmful and dangerous to human health due to high toxicity and strong carcinogenicity.Exploring sensitive material to effectively detect p-xylene is of importance.In this paper,perovskite single crystal(C_(4)H_(9)NH_(3))_(2)PbI_(4) has been successfully synthesized via solution method.The obtained product was analyzed by single crystal X-ray diffraction.With the space group Pbca,orthorhombic(C_(4)H_(9)NH_(3))_(2)PbI_(4) layered perovskite structure consists of an extended two-dimensional network of corner-sharing PbI_(6) octahedron.Single layer perovskite sheets of distorted PbI_(6) octahedron alternated with protonated n-butylammonium cation bilayers,which offers many advantages and provides the possibility of forming a gas sensor device based on the change of resistances.Density functional theory(DFT)simulations regarding the adsorption energy revealed that this organicinorganic hybrid perovskite compound has excellent selectivity toward p-xylene compared with other gases including C_(2)H_(5)OH,C_(6)H_(6),CH_(2)Cl_(2),HCHO,CH_(3)COCH_(3) and C_(7)H_(8).The calculation of electron density,density of states and electron density difference showed the sensing mechanism of p-C_(8)H_(10) is mainly derived from physical adsorption-desorption in view of electron transfer.展开更多
文摘This paper deals with thermodynamic chemical equilibrium analysis using the method of direct minimization of Gibbs free energy for all possible CH4 and CO2 reactions. The effects of CO2/CH4 feed ratio, reaction temperature, and system pressure on equilibrium composition, conversion, selectivity and yield were studied. In addition, carbon and no carbon formation regions were also considered at various reaction temperatures and CO2/CH4 feed ratios in the reaction system at equilibrium. It was found that the reaction temperature above 1100 K and CO2/CH4 ratio=1 were favourable for synthesis gas production with H2/CO ratio unity, while carbon dioxide oxidative coupling of methane (CO2 OCM) reaction to produce ethane and ethylene is less favourable thermodynamically. Numerical results indicated that the no carbon formation region was at temperatures above 1000 K and CO2/CH4 ratio larger than 1.
基金Supports from the National Natural Science Foundation of China(No 29776037)
文摘In this paper the effect of catalyst and carrier in electric field enhanced plasma on methane conversion into C2 hydrocarbons was investigated. Methane coupling reaction was studied in the system of continuous flow reactor on Ni, MoO3, MnO2 catalysts and different ZSM-5 carriers. The per pass conversion of methane can be as high as 22%, the selectivity of ethylene can be as high as 23.8%, of acetylene 60.8%, of ethane 5.4% and of total C2 hydrocarbons was more than 90%. ZSM-5-25 was the better carrier and MnO2 was the better active component. The efficiency of energy was as high as 7.81%.
文摘Direct conversion of methane to C_2 hydrocarbons via cold plasma reactionwith catalysts has been studied at room temperature and atmospheric pressure. Methane can beconverted into C_2 hydrocarbons in different selectivity depending on the form of the reactor, powerof plasma, flow rate of methane, ratio of N_2/CH_4 and nature of the catalysts. The selectivity toC_2 hydrocarbons can reach as high as 98.64%, and the conversion of methane as high as 60% and theyield of C_2 hydrocarbons as high as 50% are obtained. Coking can be minimized under the conditionsof: proper selection of the catalysts, appropriate high flow rate of inlet methane and suitableratio of N_2 to CH_4. The catalyst surface provides active sites for radical recombination.
基金The authors gratefully thank the National Natural Science Foundation of China(No.22002189)Central South University Research Programme of Advanced Interdisciplinary Studies(No.2023QYJC012)+1 种基金Central South University Innovation-Driven Research Program(No.2023CXQD042)the Fundamental Research Funds for the Central Universities of Central South University(No.2023ZZTS0962).
文摘The use of gas diffusion electrode(GDE)based flow cell can realize industrial-scale CO_(2) reduction reactions(CO_(2)RRs).Controlling local CO_(2) and CO intermediate diffusion plays a key role in CO_(2)RR toward multi-carbon(C_(2+))products.In this work,local CO_(2) and CO intermediate diffusion through the catalyst layer(CL)was investigated for improving CO_(2)RR toward C_(2+)products.The gas permeability tests and finite element simulation results indicated CL can balance the CO_(2) gas diffusion and residence time of the CO intermediate,leading to a sufficient CO concentration with a suitable CO_(2)/H_(2)O supply for high C_(2+)products.As a result,an excellent selectivity of C_(2+)products~79%at a high current density of 400 mA·cm^(-2) could be obtained on the optimal 500 nm Cu CL(Cu500).This work provides a new insight into the optimization of CO_(2)/H_(2)O supply and local CO concentration by controlling CL for C_(2+)products in CO_(2)RR flow cell.
基金Supported by the National Natural Science Foundation of China(51104143).
文摘In the past two decades,research on C_(2)storage in coal seams and simultaneously enhanced coalbed methane recovery(ECBM)has attracted a lot of attention due to its win–win effect between greenhouse gas(C_(2))emission reduction and coalbed methane recovery enhancement.This paper presents an overview on the current status of research on C_(2)-ECBM in the past two decades,which involves C_(2)storage capacity evaluations,laboratory investigations,modelings and pilot tests.The current status shows that we have made great progress in the ECBM technology study,especially in the understanding of the ECBM mechanisms.However,there still have many technical challenges,such as the definition of unmineable coal seams for C_(2)storage capacity evaluation and storage site characterization,methods for C_(2)injectivity enhancement,etc.The low injectivity of coal seams and injectivity loss with C_(2)injection are the major technique challenges of ECBM.We also search several ways to promote the advancement of ECBM technology in the present stage,such as integrating ECBM with hydraulic fracturing,using a gas mixture instead of pure C_(2)for injection into coal seams and the application of ECBM to underground coal mines.
基金Financially supported by aspecial fund of the Education Committee of Shaanxi province(No.2000K13-G19and2002K09-G21)
文摘The infrared emission spectra of methane, H, CH' and C_2 hydrocarbons in natural gas were measured. The processes of methane decomposition and formation of C_2 hydrocarbons were studied. The experiment shows that methane decomposition can be divided into three periods as the reaction proceeds. In the first period, a large number of free radicals were formed. While in the last period, the formation of C_2 hydrocarbons and the decrease of free radicals were observed. The time and conditions of methane decomposition and formation of C_2 hydrocarbons are different.
基金the National Natural Science Foundation of China (21871104, 21621001 and U1967215)the 111 project the Ministry of Education of China (B17020)
文摘Nitrogen-rich porous organic polymers have shown great potentials in gas adsorption/separation,photocatalysis,electrochemistry,sensing and so on.Herein,1,2,3-triazole functionalized triazine-based porous organic polymers(TT-POPs)have been synthesized by the copper-catalyzed azide-alkyne cycloaddition(Cu-AAC)polymerization reactions of 1,3,5-tris(4-azidophenyl)-triazine with 1,4-diacetylene benzene and 1,3,5-triacetylenebenzene,respectively.The characterizations of N2 adsorption at 77 K show TTPOPs possess permanent porosity with BET surface areas of 666 m^(2)·g^(-1)(TT-POP-1)and 406 m^(2)·g^(-1)(TT-POP-2).The adsorption capacities of TT-POPs for CO_(2),CH4,C2H2 and C2H4,as well as the selective separation abilities of CO_(2)/N2,CO_(2)/CH_(4),C_(2)H_(2)/CH_(4) and C_(2)H_(4)/CH_(4) were evaluated.The gas selective separation ratio of TT-POPs was calculated by the ideal adsorbed solution theory(IAST)method,wherein the selective separation ratios of C_(2)H_(2)/CH_(4) and C_(2)H_(4)/CH_(4) of TT-POP-2 was 48.4 and 13.6(298 K,0.1 MPa),which is comparable to other adsorbents(5.6–120.6 for C_(2)H_(2)/CH_(4),10–26 for C_(2)H_(4)/CH_(4)).This work shows that the 1,2,3-triazole functionalized triazine-based porous organic polymer has a good application prospect in natural gas purification.
基金supported under the strategic academic leadership program“Priority 2030”of the Russian Federation(Agreement 075-15-2021-1333 dated 30.09.2021).
文摘The paper is devoted to the two-phase flow simulation.The gas-condensate mixture flow in a horizontal pipe under high pressure is considered.The influence of the equation of state(EOS)choice for mixture properties modelling on the flow regime calculation results is studied for gas with high content of methane homologues.An analytical overview of the methods to predict the flow pattern is provided.Based on this analysis,two techniques are selected.For these techniques,values of density and viscosity for each phase are required.Density calculation for the gas phase is performed with Van der Waals based EOS.The propriate EOS is selected based on studies of calculation errors for test mixtures.Calculation of liquid phase density is done by means of Patela-Teja and Guo-Du equations,two different models are considered for viscosity estimation.The flow patterns of gas-condensate mixture in a range of temperatures and pressures are calculated and verified via probability map.The results of study allow to recommend the Brusilovsky EOS for calculation of densities for similar gas mixtures and make more rigorous flow regime evaluation.The probability map shows that for the chosen composition and parameters of media the flow pattern is mostly transitional between segregated and annular independent from EOS.
基金This work was supported by the Science and Technology Development from the SINOPEC (Grant No. X500005) the National Natural Science Foundation of China (Grant No. 29776037).
文摘The experiments are carried out in the system of continuous flow reactors with dielectric-barrier discharge (DBD) for studies on the conversion of natural gas to C2 hydrocarbons through plasma catalysis under the atmosphere pressure and room temperature. The influence of discharge frequency, structure of electrode, discharge voltage, number of electrode, ratio of H2/CH4, flow rate and catalyst on conversion of methane and selectivity of C2 hydrocarbons are investigated. At the same time, the reaction process is investigated. Higher conversion of methane and selectivity of C2 hydrocarbons are achieved and deposited carbons are eliminated by proper choice of parameters. The appropriate operation parameters in dielectric-barrier discharge plasma field are that the supply voltage is 20-40 kV (8.4-40 W), the frequency of power supply is 20 kHz, the structure of (b) electrode is suitable, and the flow of methane is 20-60 ml · min-1. The conversion of methane can reach 45%, the selectivity of C2 hydrocarbons
基金financially supported by the National Natural Science Foundation of China(No.U19A2070)the National Science Funds for Excellent Young Scholars of China(No.61822106)the National Science Funds for Creative Research Groups of China(No.61421002)。
文摘Ti_(3)C_(2)T_(x),which is a novel two-dimensional(2 D)material,has received enormous interest in the field of sensor technology due to its large surface area,excellent electrical conductivity,and abundant active surface sites.In recent years,several Ti_(3)C_(2)T_(x)-based gases and humidity sensors have been developed and reported.In this review,we focus on the latest applications of Ti_(3)C_(2)T_(x)-based nanomaterials in gas and humidity sensors.First,the synthesis of Ti_(3)C_(2)T_(x) from the dangerous fluorine-containing etching process to the safe fluorine-free preparation method was discussed,and the structures of the Ti_(3)C_(2)T_(x) controlled by different delamination methods were also outlined.Subsequently,the functionalization of pristine Ti_(3)C_(2)T_(x) and composite strategies for enhancing its gas and humidity sensing performance were reviewed.In addition,the gas and humidity sensing mechanisms of sensors based on Ti_(3)C_(2)T_(x) were also summarized.Finally,the challenges and opportunities for the use of Ti_(3)C_(2)T_(x) gas and humidity sensors were discussed to provide guidance on the promising potential of Ti_(3)C_(2)T_(x) in this field.
基金The Postgraduate Innovative Research Projects of Tianjin。
文摘Separation of C_(2) gases(C_(2)H_(2)/C_(2)H_(4),C_(2)H_(6)/C_(2)H_(4) and C_(2)H_(2)/CO_(2))mixtures is one of the most important and energy-demanding processes in chemical industry.Traditional separation methods(fine distillation separation and selective catalytic hydrogenation separation)have the shortages of high energy consumption and inefficient use of resources,affecting the achievement of peak carbon dioxide emissions and carbon neutrality targets.Separation based on adsorption is considered as one of the best ways to achieve low-energy separations.Therefore,it is of great importance to synthesize materials that enable the effective separation and purification of C_(2) gases under mild conditions.As an emerging class of porous materials,metal-organic frameworks(MOFs)show great promise in the field of gas separation and purification due to their ultra-high specific surface area,easily modifiable pore surfaces,structural designability and functionalization.Herein,we summarize recent research advances by use of MOFs sorbents for the separation and purification of C_(2) gases,including C_(2)H_(2)/C_(2)H_(4),C_(2)H_(6)/C_(2)H_(4) and C_(2)H_(2)/CO_(2).Relationship between structures and separation mechanism is also explored.Furthermore,challenges and possible research directions related to the further exploration are also discussed.
文摘By using the methods of hydrocarbon generation kinetics and carbon isotope kinetics, combined with geological background of natural gas pool formation, the generation and accumulation of natural gas from Yinan 2 gas pool was studied in Kuqa Depression of the Tarim Basin. Natural gas of Yinan 2 gas pool is mainly derived from Middle and Lower Jurassic coal-bearing source rocks, and generally belongs to long time-accumulated gas. It is suggested that Yinan 2 gas is chiefly accumulated in the last 5 Ma, its Ro ranges from 1.25% to 1.95%, and the loss rate of natural gas is about 25%-30%. This work not only complements and reduces the deficiency of formation model of natural gas pools which traditionally depends on the matching relationships between source rock, reservoir, cap rock, and trap, but also is a useful reference in the study of other gas pools.
基金supported financially by the National Natural Science Foundation of China(Nos.,51572158 and 51972200)the Graduate Innovation Fund of Shaanxi University of Science&Technology+2 种基金funded by the Japan Society for the Promotion of Science(JSPS)Grant-in-Aid for the Scientific Research(KAKENHI Nos.20H00297 and Innovative Area“Mixed Anion”(No.16H06439))the Nippon Sheet Glass Foundation for Materials Science and Engineeringby the Dynamic Alliance for Open Innovations Bridging Human,Environment and Materials,the Cooperative Research Program of“Network Joint Research Center for Materials and Devices”。
文摘Acetone,as widely used reagents in industry and laboratories,are extremely harmful to the human.So the detection of acetone gas concentrations and leaks in special environments at room temperature is essential.Herein,the nanocomposite combining SnO-SnO_(2)(p-n junction)and Ti_(3)C_(2)T_(x) MXene was successfully synthesized by a one-step hydrothermal method.Because of the existence of a small amount of oxygen during the hydrothermal conditions,part of the p-type SnO was oxidized to n-type SnO_(2),forming in-situ p-n junctions on the surface of Sn O.The hamburger-like SnO-SnO_(2)/Ti_(3)C_(2)T_(x) sensor exhibited improved acetone gas sensing response of 12.1(R_(g)/R_(a))at room temperature,which were nearly 11 and 4 times higher than those of pristine Ti_(3)C_(2)T_(x) and pristine SnO-SnO_(2),respectively.Moreover,it expressed a short recovery time(9 s)and outstanding reproducibility.Because of the different work functions,the Schottky barrier was formed between the SnO and the Ti_(3)C_(2)T_(x) nanosheets,acting as a hole accumulation layer(HALs)between Ti_(3)C_(2)T_(x) and tin oxides.Herein,the sensing mechanism based on the formation of hetero-junctions and high conductivity of the metallic phase of Ti_(3)C_(2)T_(x) MXene in SnO-SnO_(2)/Ti_(3)C_(2)T_(x) sensors was discussed in detail.
基金This work was financially supported by the University of Science and Technology of China(USTC)(No.KY2060000150)the Fundamental Research Funds for the Central Universities(No.WK2060000040).We are thankful for the support from the USTC Center for Micro and Nanoscale Research and Fabrication and the Supercomputing Center of the USTC.
文摘With the disruptive carbon cycle being blamed for global warming,the plausible electrocatalytic CO_(2)reduction reaction(CO_(2)RR)to form valuable C_(2+)hydrocarbons and feedstock is becoming a hot topic.Cu-based electrocatalysts have been proven to be excellent CO_(2)RR alternatives for high energy value-added products in this regard.However,the selectivity of CO_(2)RR to form C_(2+)products via Cu-based catalysts suffers from a high overpotential,slow reaction kinetics,and low selectivity.This review attempts to discuss various cutting-edge strategies for understanding catalytic design such as Cu-based catalyst surface engineering,tuning Cu bandgap via alloying,nanocatalysis,and the effect of the electrolyte and pH on catalyst morphology.The most recent advances in in situ spectroscopy and computational techniques are summarized to fully comprehend reaction mechanisms,structural transformation/degradation mechanisms,and crystal facet loss with subsequent effects on catalyst activity.Furthermore,approaches for tuning Cu interactions are discussed from four key perspectives:single-atom catalysts,interfacial engineering,metal-organic frameworks,and polymer-incorporated materials,which provide new insights into the selectivity of C_(2+)products.Finally,major challenges are outlined,and potential prospects for the rational design of catalysts for robust CO_(2)RR are proposed.The integration of catalytic design with mechanistic understanding is a step forward in the promising advancement of CO_(2)RR technology for industrial applications.
基金financially supported by the Natural Science Foundation of Hebei(Nos.F2020202027 and F2020202067)the Major National Science and Technology Special Projects(No.2016ZX02301003-004-007)+1 种基金the National Natural Science Foundation of China(No.21271139)the Natural Science Foundation of Tianjin(No.17JCTPJC54500)。
文摘P-xylene(p-C_(8)H_(10))is extremely harmful and dangerous to human health due to high toxicity and strong carcinogenicity.Exploring sensitive material to effectively detect p-xylene is of importance.In this paper,perovskite single crystal(C_(4)H_(9)NH_(3))_(2)PbI_(4) has been successfully synthesized via solution method.The obtained product was analyzed by single crystal X-ray diffraction.With the space group Pbca,orthorhombic(C_(4)H_(9)NH_(3))_(2)PbI_(4) layered perovskite structure consists of an extended two-dimensional network of corner-sharing PbI_(6) octahedron.Single layer perovskite sheets of distorted PbI_(6) octahedron alternated with protonated n-butylammonium cation bilayers,which offers many advantages and provides the possibility of forming a gas sensor device based on the change of resistances.Density functional theory(DFT)simulations regarding the adsorption energy revealed that this organicinorganic hybrid perovskite compound has excellent selectivity toward p-xylene compared with other gases including C_(2)H_(5)OH,C_(6)H_(6),CH_(2)Cl_(2),HCHO,CH_(3)COCH_(3) and C_(7)H_(8).The calculation of electron density,density of states and electron density difference showed the sensing mechanism of p-C_(8)H_(10) is mainly derived from physical adsorption-desorption in view of electron transfer.