The printed circuit heat exchanger(PCHE) is receiving wide attention as a new kind of compact heat exchanger and is considered as a promising vaporizer in the LNG process. In this paper, a PCHE straight channel in the...The printed circuit heat exchanger(PCHE) is receiving wide attention as a new kind of compact heat exchanger and is considered as a promising vaporizer in the LNG process. In this paper, a PCHE straight channel in the length of 500 mm is established, with a semicircular cross section in a diameter of 1.2 mm.Numerical simulation is employed to investigate the flow and heat transfer performance of supercritical methane in the channel. The pseudo-boiling theory is adopted and the liquid-like, two-phase-like, and vapor-like regimes are divided for supercritical methane to analyze the heat transfer and flow features.The results are presented in micro segment to show the local convective heat transfer coefficient and pressure drop. It shows that the convective heat transfer coefficient in segments along the channel has a significant peak feature near the pseudo-critical point and a heat transfer deterioration when the average fluid temperature in the segment is higher than the pseudo-critical point. The reason is explained with the generation of vapor-like film near the channel wall that the peak feature related to a nucleateboiling-like state and heat transfer deterioration related to a film-boiling-like state. The effects of parameters, including mass flow rate, pressure, and wall heat flux on flow and heat transfer were analyzed.In calculating of the averaged heat transfer coefficient of the whole channel, the traditional method shows significant deviation and the micro segment weighted average method is adopted. The pressure drop can mainly be affected by the mass flux and pressure and little affected by the wall heat flux. The peak of the convective heat transfer coefficient can only form at high mass flux, low wall heat flux, and near critical pressure, in which condition the nucleate-boiling-like state is easier to appear. Moreover,heat transfer deterioration will always appear, since the supercritical flow will finally develop into a filmboiling-like state. So heat transfer deterioration should be taken seriously in the design and safe operation of vaporizer PCHE. The study of this work clarified the local heat transfer and flow feature of supercritical methane in microchannel and contributed to the deep understanding of supercritical methane flow of the vaporization process in PCHE.展开更多
Deep coal seams show low permeability,low elastic modulus,high Poisson’s ratio,strong plasticity,high fracture initiation pressure,difficulty in fracture extension,and difficulty in proppants addition.We proposed the...Deep coal seams show low permeability,low elastic modulus,high Poisson’s ratio,strong plasticity,high fracture initiation pressure,difficulty in fracture extension,and difficulty in proppants addition.We proposed the concept of large-scale stimulation by fracture network,balanced propagation and effective support of fracture network in fracturing design and developed the extreme massive hydraulic fracturing technique for deep coalbed methane(CBM)horizontal wells.This technique involves massive injection with high pumping rate+high-intensity proppant injection+perforation with equal apertures and limited flow+temporary plugging and diverting fractures+slick water with integrated variable viscosity+graded proppants with multiple sizes.The technique was applied in the pioneering test of a multi-stage fracturing horizontal well in deep CBM of Linxing Block,eastern margin of the Ordos Basin.The injection flow rate is 18 m^(3)/min,proppant intensity is 2.1 m^(3)/m,and fracturing fluid intensity is 16.5 m^(3)/m.After fracturing,a complex fracture network was formed,with an average fracture length of 205 m.The stimulated reservoir volume was 1987×10^(4)m^(3),and the peak gas production rate reached 6.0×10^(4)m^(3)/d,which achieved efficient development of deep CBM.展开更多
In the pursuit of global net zero carbon emissions and climate change mitigation,ongoing research into sustainable energy sources and emission control is paramount.This review examines methane leakage from abandoned o...In the pursuit of global net zero carbon emissions and climate change mitigation,ongoing research into sustainable energy sources and emission control is paramount.This review examines methane leakage from abandoned oil and gas(AOG)wells,focusing particularly on Lubbock,a geographic area situated within the larger region known as the Permian Basin in West Texas,United States.The objective is to assess the extent and environmental implications of methane leakage from these wells.The analysis integrates pertinent literature,governmental and industry data,and prior Lubbock reports.Factors affecting methane leakage,including well integrity,geological characteristics,and human activities,are explored.Our research estimates 1781 drilled wells in Lubbock,forming a foundation for targeted assessments and monitoring due to historical drilling trends.The hierarchy of well statuses in Lubbock highlights the prevalence of“active oil wells,”trailed by“plugged and abandoned oil wells”and“inactive oil wells.”Methane leakage potential aligns with these well types,underscoring the importance of strategic monitoring and mitigation.The analysis notes a zenith in“drilled and completed”wells during 1980-1990.While our study's case analysis and literature review reiterate the critical significance of assessing and mitigating methane emissions from AOG wells,it's important to clarify that the research does not directly provide methane leakage data.Instead,it contextualizes the issue's magnitude and emphasizes the well type and status analysis's role in targeted mitigation efforts.In summary,our research deepens our understanding of methane leakage,aiding informed decision-making and policy formulation for environmental preservation.By clarifying well type implications and historical drilling patterns,we aim to contribute to effective strategies in mitigating methane emissions from AOG wells.展开更多
On 4 March 2024,a new methane-observing satellite,MethaneSAT,was launched atop a SpaceX Falcon 9 rocket and successfully placed in orbit[1].Developed by the New York City,NY,USA-headquartered Environmental Defense Fun...On 4 March 2024,a new methane-observing satellite,MethaneSAT,was launched atop a SpaceX Falcon 9 rocket and successfully placed in orbit[1].Developed by the New York City,NY,USA-headquartered Environmental Defense Fund(EDF)in partnership with the New Zealand Space Agency and funded by multiple philanthropic donors including the Bezos Earth Fund,the spacecraft promises to greatly improve scientists’ability to pinpoint and monitor methane emissions,particularly those related to the oil and gas industry.展开更多
Plasma catalysis has recently gained increased attention for its application in gas conversion,notably in processes like the dry reforming of methane aimed at transforming them into valuable chemicals and fuels.As thi...Plasma catalysis has recently gained increased attention for its application in gas conversion,notably in processes like the dry reforming of methane aimed at transforming them into valuable chemicals and fuels.As this field is still in its early developmental stages,there is a crucial necessity to explore the synergistic mechanism between plasma and catalysts.The optimization of catalysts is imperative to improve their selectivity and conversion rates for desired products in a plasma environment.Additionally,delving into microscale investigations of plasma characteristics,such as electron temperature and the density of energetic species,is essential to enhance the stability and activity of catalysts.This review examines recent advancements in various methane conversion techniques,encompassing Dry Reforming of Methane,Steam Methane Reforming,Pa rtial Oxidation of Metha ne,and Methane Decomposition utilizing non-thermal dielectric barrier discharge(DBD)plasma.The aim is to gain a deeper understanding of plasma-catalyst interactions and to refine catalyst selection strategies for maximizing the production of desired products such as syngas,oxygenates,or higher hydrocarbons.The review delves into the catalytic mechanisms that delineate the synergistic effects between DBD plasma and catalyst in each technology,shedding light on the role of diverse catalytic properties in activating methane molecules-a pivotal step in hybrid plasma-catalytic reactions.Various approaches employed by researchers in exploring suitable catalysts and optimal reaction conditions to bolster CH_(4) conversion rates and selectivity using DBD plasma are discussed.Additionally,the review identifies gaps in the realm of plasma catalysis,underscoring the necessity for further research to fully understand the underlying principles of plasma and catalyst which are not trivial to uncover.展开更多
The challenges posed by energy and environmental issues have forced mankind to explore and utilize unconventional energy sources.It is imperative to convert the abundant coalbed gas(CBG)into high value-added products,...The challenges posed by energy and environmental issues have forced mankind to explore and utilize unconventional energy sources.It is imperative to convert the abundant coalbed gas(CBG)into high value-added products,i.e.,selective and efficient conversion of methane from CBG.Methane activation,known as the“holy grail”,poses a challenge to the design and development of catalysts.The structural complexity of the active metal on the carrier is of particular concern.In this work,we have studied the nucleation growth of small Co clusters(up to Co_(6))on the surface of CeO_(2)(110)using density functional theory,from which a stable loaded Co/CeO_(2)(110)structure was selected to investigate the methane activation mechanism.Despite the relatively small size of the selected Co clusters,the obtained Co_(x)/CeO_(2)(110)exhibits interesting properties.The optimized Co_(5)/CeO_(2)(110)structure was selected as the optimal structure to study the activation mechanism of methane due to its competitive electronic structure,adsorption energy and binding energy.The energy barriers for the stepwise dissociation of methane to form CH3^(*),CH2^(*),CH^(*),and C^(*)radical fragments are 0.44,0.55,0.31,and 1.20 eV,respectively,indicating that CH^(*)dissociative dehydrogenation is the rate-determining step for the system under investigation here.This fundamental study of metal-support interactions based on Co growth on the CeO_(2)(110)surface contributes to the understanding of the essence of Co/CeO_(2) catalysts with promising catalytic behavior.It provides theoretical guidance for better designing the optimal Co/CeO_(2) catalyst for tailored catalytic reactions.展开更多
Co-combustion of methane(CH4)and acid gas(AG)is required to sustain the temperature in Claus reaction furnace.In this study,oxy-fuel combustion of methane and acid gas has been experimentally studied in a diffusion fl...Co-combustion of methane(CH4)and acid gas(AG)is required to sustain the temperature in Claus reaction furnace.In this study,oxy-fuel combustion of methane and acid gas has been experimentally studied in a diffusion flame.Three equivalence ratios(ER=1.0,1.5,2.0)and CH_(4)-addition ratios(CH_(4)/AG=0.3,0.5,0.7)were examined and the flame was interpreted by analyzing the distributions of the temperature and species concentration along central axial.CH_(4)-AG diffusion flame could be classified into three sections namely initial reaction,oxidation and complex reaction sections.Competitive oxidation of CH_(4)and H_(2)S was noted in the first section wherein H_(2)S was preferred and both were mainly proceeding decomposition and partial oxidation.SO_(2)was formed at oxidation section together with obvious presence of H2 and CO.However,H2 and CO were inclined to be sustained under fuel rich condition in the complex reaction section.Reducing ER and increasing CH4/AG contributed to higher temperature,H_(2)S and CH_(4)oxidation and CO_(2)reactivity.Hence a growing trend for CH_(4)and AG to convert into H_(2),CO and SO_(2)could be witnessed.And this factor enhanced the generation of CS2 and COS in the flame inner core by interactions of CH4 and CO_(2)with sulfur species.COS was formed through the interactions of CO and CO_(2)with sulfur species.The CS_(2)production directly relied on reaction of CH_(4)with sulfur species.The concentration of COS was greater than CS_(2)since CS_(2)was probably inhibited due to the presence of H_(2).COS and CS_(2)could be consumed by further oxidation or other complex reactions.展开更多
Anthropogenic methane emissions are a leading cause of the increase in global averagetemperatures,often referred to as global warming.Flooded soils play a significant role in methaneproduction,where the anaerobic cond...Anthropogenic methane emissions are a leading cause of the increase in global averagetemperatures,often referred to as global warming.Flooded soils play a significant role in methaneproduction,where the anaerobic conditions promote the production of methane by methanogenicmicroorganisms.Rice fields contribute a considerable portion of agricultural methane emissions,as riceplants provide both factors that enhance and limit methane production.Rice plants harbor both methaneproducingand methane-oxidizing microorganisms.Exudates from rice roots provide source for methaneproduction,while oxygen delivered from the root aerenchyma enhances methane oxidation.Studies haveshown that the diversity of these microorganisms depends on rice cultivars with some genes characterizedas harboring specific groups of microorganisms related to methane emissions.However,there is still aneed for research to determine the balance between methane production and oxidation,as rice plantspossess the ability to regulate net methane production.Various agronomical practices,such as fertilizerand water management,have been employed to mitigate methane emissions.Nevertheless,studiescorrelating agronomic and chemical management of methane with productivity are limited.Moreover,evidences for breeding low-methane-emitting rice varieties are scattered largely due to the absence ofcoordinated breeding programs.Research has indicated that phenotypic characteristics,such as rootbiomass,shoot architecture,and aerenchyma,are highly correlated with methane emissions.This reviewdiscusses available studies that involve the correlation between plant characteristics and methaneemissions.It emphasizes the necessity and importance of breeding low-methane-emitting rice varieties inaddition to existing agronomic,biological,and chemical practices.The review also delves into the idealphenotypic and physiological characteristics of low-methane-emitting rice and potential breeding techniques,drawing from studies conducted with diverse varieties,mutants,and transgenic plants.展开更多
The rich accumulation of methane(CH_(4))in tectonic coal layers poses a significant obstacle to the safe and efficient extraction of coal seams and coalbed methane.Tectonic coal samples from three geologically complex...The rich accumulation of methane(CH_(4))in tectonic coal layers poses a significant obstacle to the safe and efficient extraction of coal seams and coalbed methane.Tectonic coal samples from three geologically complex regions were selected,and the main results obtained by using a variety of research tools,such as physical tests,theoretical analyses,and numerical simulations,are as follows:22.4–62.5 nm is the joint segment of pore volume,and 26.7–100.7 nm is the joint segment of pore specific surface area.In the dynamic gas production process of tectonic coal pore structure,the adsorption method of methane molecules is“solid–liquid adsorption is the mainstay,and solid–gas adsorption coexists”.Methane stored in micropores with a pore size smaller than the jointed range is defined as solid-state pores.Pores within the jointed range,which transition from micropore filling to surface adsorption,are defined as gaseous pores.Pores outside the jointed range,where solid–liquid adsorption occurs,are defined as liquid pores.The evolution of pore structure affects the methane adsorption mode,which provides basic theoretical guidance for the development of coal seam resources.展开更多
This study investigates the dry reformation of methane(DRM)over Ni/Al_(2)O_(3)catalysts in a dielectric barrier discharge(DBD)non-thermal plasma reactor.A novel hybrid machine learning(ML)model is developed to optimiz...This study investigates the dry reformation of methane(DRM)over Ni/Al_(2)O_(3)catalysts in a dielectric barrier discharge(DBD)non-thermal plasma reactor.A novel hybrid machine learning(ML)model is developed to optimize the plasma-catalytic DRM reaction with limited experimental data.To address the non-linear and complex nature of the plasma-catalytic DRM process,the hybrid ML model integrates three well-established algorithms:regression trees,support vector regression,and artificial neural networks.A genetic algorithm(GA)is then used to optimize the hyperparameters of each algorithm within the hybrid ML model.The ML model achieved excellent agreement with the experimental data,demonstrating its efficacy in accurately predicting and optimizing the DRM process.The model was subsequently used to investigate the impact of various operating parameters on the plasma-catalytic DRM performance.We found that the optimal discharge power(20 W),CO_(2)/CH_(4)molar ratio(1.5),and Ni loading(7.8 wt%)resulted in the maximum energy yield at a total flow rate of∼51 mL/min.Furthermore,we investigated the relative significance of each operating parameter on the performance of the plasma-catalytic DRM process.The results show that the total flow rate had the greatest influence on the conversion,with a significance exceeding 35%for each output,while the Ni loading had the least impact on the overall reaction performance.This hybrid model demonstrates a remarkable ability to extract valuable insights from limited datasets,enabling the development and optimization of more efficient and selective plasma-catalytic chemical processes.展开更多
Ni/TiO_(2) catalyst is widely employed for photo-driven DRM reaction while the influence of crystal structure of TiO_(2) remains unclear.In this work,the rutile/anatase ratio in supports was successfully controlled by...Ni/TiO_(2) catalyst is widely employed for photo-driven DRM reaction while the influence of crystal structure of TiO_(2) remains unclear.In this work,the rutile/anatase ratio in supports was successfully controlled by varying the calcination temperature of anatase-TiO_(2).Structural characterizations revealed that a distinct TiO_(x) coating on the Ni nanoparticles(NPs)was evident for Ni/TiO_(2)-700 catalyst due to strong metal-support interaction.It is observed that the TiOx overlayer gradually disappeared as the ratio of rutile/anatase increased,thereby enhancing the exposure of Ni active sites.The exposed Ni sites enhanced visible light absorption and boosted the dissociation capability of CH4,which led to the much elevated catalytic activity for Ni/TiO_(2)-950 in which rutile dominated.Therefore,the catalytic activity of solar-driven DRM reaction was significantly influenced by the rutile/anatase ratio.Ni/TiO_(2)-950,characterized by a predominant rutile phase,exhibited the highest DRM reactivity,with remarkable H_(2) and CO production rates reaching as high as 87.4 and 220.2 mmol/(g·h),respectively.These rates were approximately 257 and 130 times higher,respectively,compared to those obtained on Ni/TiO_(2)-700 with anatase.This study suggests that the optimization of crystal structure of TiO_(2) support can effectively enhance the performance of photothermal DRM reaction.展开更多
Deep coalbed methane(DCBM),an unconventional gas reservoir,has undergone significant advancements in recent years,sparking a growing interest in assessing pore pressure dynamics within these reservoirs.While some prod...Deep coalbed methane(DCBM),an unconventional gas reservoir,has undergone significant advancements in recent years,sparking a growing interest in assessing pore pressure dynamics within these reservoirs.While some production data analysis techniques have been adapted from conventional oil and gas wells,there remains a gap in the understanding of pore pressure generation and evolution,particularly in wells subjected to large-scale hydraulic fracturing.To address this gap,a novel technique called excess pore pressure analysis(EPPA)has been introduced to the coal seam gas industry for the first time to our knowledge,which employs dual-phase flow principles based on consolidation theory.This technique focuses on the generation and dissipation for excess pore-water pressure(EPWP)and excess pore-gas pressure(EPGP)in stimulated deep coal reservoirs.Equations have been developed respectively and numerical solutions have been provided using the finite element method(FEM).Application of this model to a representative field example reveals that excess pore pressure arises from rapid loading,with overburden weight transferred under undrained condition due to intense hydraulic fracturing,which significantly redistributes the weight-bearing role from the solid coal structure to the injected fluid and liberated gas within artificial pores over a brief timespan.Furthermore,field application indicates that the dissipation of EPWP and EPGP can be actually considered as the process of well production,where methane and water are extracted from deep coalbed methane wells,leading to consolidation for the artificial reservoirs.Moreover,history matching results demonstrate that the excess-pressure model established in this study provides a better explanation for the declining trends observed in both gas and water production curves,compared to conventional practices in coalbed methane reservoir engineering and petroleum engineering.This research not only enhances the understanding of DCBM reservoir behavior but also offers insights applicable to production analysis in other unconventional resources reliant on hydraulic fracturing.展开更多
Methane adsorption is a critical assessment of the gas storage capacity(GSC)of shales with geological conditions.Although the related research of marine shales has been well-illustrated,the methane adsorption of marin...Methane adsorption is a critical assessment of the gas storage capacity(GSC)of shales with geological conditions.Although the related research of marine shales has been well-illustrated,the methane adsorption of marine-continental transitional(MCT)shales is still ambiguous.In this study,a method of combining experimental data with analytical models was used to investigate the methane adsorption characteristics and GSC of MCT shales collected from the Qinshui Basin,China.The Ono-Kondo model was used to fit the adsorption data to obtain the adsorption parameters.Subsequently,the geological model of GSC based on pore evolution was constructed using a representative shale sample with a total organic carbon(TOC)content of 1.71%,and the effects of reservoir pressure coefficient and water saturation on GSC were explored.In experimental results,compared to the composition of the MCT shale,the pore structure dominates the methane adsorption,and meanwhile,the maturity mainly governs the pore structure.Besides,maturity in the middle-eastern region of the Qinshui Basin shows a strong positive correlation with burial depth.The two parameters,micropore pore volume and non-micropore surface area,induce a good fit for the adsorption capacity data of the shale.In simulation results,the depth,pressure coefficient,and water saturation of the shale all affect the GSC.It demonstrates a promising shale gas potential of the MCT shale in a deeper block,especially with low water saturation.Specifically,the economic feasibility of shale gas could be a major consideration for the shale with a depth of<800 m and/or water saturation>60%in the Yushe-Wuxiang area.This study provides a valuable reference for the reservoir evaluation and favorable block search of MCT shale gas.展开更多
Development of metal oxide semiconductors-based methane sensors with good response and low power consumption is one of the major challenges to realize the real-time monitoring of methane leakage.In this work,a self-as...Development of metal oxide semiconductors-based methane sensors with good response and low power consumption is one of the major challenges to realize the real-time monitoring of methane leakage.In this work,a self-assembled mulberry-like ZnO/SnO_(2)hierarchical structure is constructed by a two-step hydrothermal method.The resultant sensor works at room temperature with excellent response of~56.1%to 2000 ppm CH_(4)at 55%relative humidity.It is found that the strain induced at the ZnO/SnO_(2)interface greatly enhances the piezoelectric polarization on the ZnO surface and that the band bending results in the accumulation of chemically adsorbed O_(2)^(-)ions close to the interface,leading to significant improvement in the sensing performance of the methane gas sensor at room temperature.展开更多
At room temperature,the conversion of greenhouse gases into valuable chemicals using metal-free catalysts for dry reforming of methane(DRM) is quite promising and challenging.Herein,we developed a novel covalent organ...At room temperature,the conversion of greenhouse gases into valuable chemicals using metal-free catalysts for dry reforming of methane(DRM) is quite promising and challenging.Herein,we developed a novel covalent organic porous polymer (TPE-COP) with rapid charge separation of the electron–hole pairs for DRM driven by visible light at room temperature,which can efficiently generate syngas (CO and H_(2)).Both electron donor (tris(4-aminophenyl)amine,TAPA) and acceptor (4,4',4'',4'''-((1 E,1'E,1''E,1'''E)-(ethene-1,1,2,2-tetrayltetrakis (benzene-4,1-diyl))tetrakis (ethene-2,1-diyl))tetrakis (1-(4-formylbenzyl)quinolin-1-ium),TPE-CHO) were existed in TPE-COP,in which the push–pull effect between them promoted the separation of photogenerated electron–hole,thus greatly improving the photocatalytic activity.Density functional theory (DFT) simulation results show that TPE-COP can form charge-separating species under light irradiation,leading to electrons accumulation in TPE-CHO unit and holes in TAPA,and thus efficiently initiating DRM.After 20 h illumination,the photocatalytic results show that the yields reach 1123.6 and 30.8μmol g^(-1)for CO and H_(2),respectively,which are significantly higher than those of TPE-CHO small molecules.This excellent result is mainly due to the increase of specific surface area,the enhancement of light absorption capacity,and the improvement of photoelectron-generating efficiency after the formation of COP.Overall,this work contributes to understanding the advantages of COP materials for photocatalysis and fundamentally pushes metal-free catalysts into the door of DRM field.展开更多
It is urgent to develop catalysts with application potential for oxidative coupling of methane(OCM)at relatively lower temperature.Herein,three-dimensional ordered macro porous(3 DOM)La_(2-x)Sr_(x)Ce_(2-y)CayO_(7-δ)(...It is urgent to develop catalysts with application potential for oxidative coupling of methane(OCM)at relatively lower temperature.Herein,three-dimensional ordered macro porous(3 DOM)La_(2-x)Sr_(x)Ce_(2-y)CayO_(7-δ)(A_(2)B_(2)O_(7)-type)catalysts with disordered defective cubic fluorite phased structure were successfully prepared by a colloidal crystal template method.3DOM structure promotes the accessibility of the gaseous reactants(O2and CH4)to the active sites.The co-doping of Ca and Sr ions in La_(2-x)Sr_(x)Ce_(2-y)CayO_(7-δ)catalysts improved the formation of oxygen vacancies,thereby leading to increased density of surface-active oxygen species(O_(2)^(-))for the activation of CH4and the formation of C2products(C2H6and C2H4).3DOM La_(2-x)Sr_(x)Ce_(2-y)CayO_(7-δ)catalysts exhibit high catalytic activity for OCM at low temperature.3DOM La1.7Sr0.3Ce1.7Ca0.3O7-δcatalyst with the highest density of O_(2)^(-)species exhibited the highest catalytic activity for low-temperature OCM,i.e.,its CH4conversion,selectivity and yield of C2products at 650℃are 32.2%,66.1%and 21.3%,respectively.The mechanism was proposed that the increase in surface oxygen vacancies induced by the co-doping of Ca and Sr ions boosts the key step of C-H bond breaking and C-C bond coupling in catalyzing low-temperature OCM.It is meaningful for the development of the low-temperature and high-efficient catalysts for OCM reaction in practical application.展开更多
1.Challenges circular methane energy systems In recent decades,methane-based energy systems have rapidly gained traction across the globe because of the increasing availability of low-cost methane production capacity....1.Challenges circular methane energy systems In recent decades,methane-based energy systems have rapidly gained traction across the globe because of the increasing availability of low-cost methane production capacity.However,fossil methane production and combustion lead to large greenhouse gas emissions,contributing to climate change[1].展开更多
Direct methane conversion has advantages such as low energy consumption,less processes,and being more economical.However,it is difficult to activate methane at room temperature due to the high dissociation energy of C...Direct methane conversion has advantages such as low energy consumption,less processes,and being more economical.However,it is difficult to activate methane at room temperature due to the high dissociation energy of C-H bonds of methane.Additionally,the target products,such as methanol,acetic acid,and other oxygenates,are prone to overoxidation,resulting in the generation of CO_(2).Therefore,the design of catalysts with high activity and selectivity is important.展开更多
Power-to-methane(P2M)processes,by converting electricity from renewable energy to H2and then into other high value-added and energy-intense chemicals in the presence of active catalysts,have become an effective soluti...Power-to-methane(P2M)processes,by converting electricity from renewable energy to H2and then into other high value-added and energy-intense chemicals in the presence of active catalysts,have become an effective solution for energy storage.However,the fluctuating electricity from intermittent renewable energy leads to a dynamic composition of reactants for downstream methanation,which requires an excellent heterogeneous catalyst to withstand the harsh conditions.Based on these findings,the objective of this review is to classify the fundamentals and status of CO/CO_(2)methanation and identify the pathways in the presence of various catalysts for methane production.In addition,this review sheds insight into the future development and challenges of CO_(2)or CO methanation,including the deactivation mechanisms and catalyst performance under dynamically harsh conditions.Finally,we elaborated on the advantages and development prospects of P2M,and then we summarized the current stage and ongoing industrialization projects of P2M.展开更多
Background Sustainable strategies for enteric methane(CH_(4))mitigation of dairy cows have been extensively explored to improve production performance and alleviate environmental pressure.The present study aimed to in...Background Sustainable strategies for enteric methane(CH_(4))mitigation of dairy cows have been extensively explored to improve production performance and alleviate environmental pressure.The present study aimed to investigate the effects of dietary xylooligosaccharides(XOS)and exogenous enzyme(EXE)supplementation on milk production,nutrient digestibility,enteric CH_(4) emissions,energy utilization efficiency of lactating Jersey dairy cows.Forty-eight lactating cows were randomly assigned to one of 4 treatments:(1)control diet(CON),(2)CON with 25 g/d XOS(XOS),(3)CON with 15 g/d EXE(EXE),and(4)CON with 25 g/d XOS and 15 g/d EXE(XOS+EXE).The 60-d experimental period consisted of a 14-d adaptation period and a 46-d sampling period.The enteric CO_(2)and CH_(4) emissions and O2 consumption were measured using two GreenFeed units,which were further used to determine the energy utilization efficiency of cows.Results Compared with CON,cows fed XOS,EXE or XOS+EXE significantly(P<0.05)increased milk yield,true protein and fat concentration,and energy-corrected milk yield(ECM)/DM intake,which could be reflected by the significant improvement(P<0.05)of dietary NDF and ADF digestibility.The results showed that dietary supplementation of XOS,EXE or XOS+EXE significantly(P<0.05)reduced CH_(4) emission,CH_(4)/milk yield,and CH_(4)/ECM.Furthermore,cows fed XOS demonstrated highest(P<0.05)metabolizable energy intake,milk energy output but lowest(P<0.05)of CH_(4) energy output and CH_(4) energy output as a proportion of gross energy intake compared with the remaining treatments.Conclusions Dietary supplementary of XOS,EXE or combination of XOS and EXE contributed to the improvement of lactation performance,nutrient digestibility,and energy utilization efficiency,as well as reduction of enteric CH_(4) emissions of lactating Jersey cows.This promising mitigation method may need further research to validate its long-term effect and mode of action for dairy cows.展开更多
基金provided by Science and Technology Development Project of Jilin Province(No.20230101338JC)。
文摘The printed circuit heat exchanger(PCHE) is receiving wide attention as a new kind of compact heat exchanger and is considered as a promising vaporizer in the LNG process. In this paper, a PCHE straight channel in the length of 500 mm is established, with a semicircular cross section in a diameter of 1.2 mm.Numerical simulation is employed to investigate the flow and heat transfer performance of supercritical methane in the channel. The pseudo-boiling theory is adopted and the liquid-like, two-phase-like, and vapor-like regimes are divided for supercritical methane to analyze the heat transfer and flow features.The results are presented in micro segment to show the local convective heat transfer coefficient and pressure drop. It shows that the convective heat transfer coefficient in segments along the channel has a significant peak feature near the pseudo-critical point and a heat transfer deterioration when the average fluid temperature in the segment is higher than the pseudo-critical point. The reason is explained with the generation of vapor-like film near the channel wall that the peak feature related to a nucleateboiling-like state and heat transfer deterioration related to a film-boiling-like state. The effects of parameters, including mass flow rate, pressure, and wall heat flux on flow and heat transfer were analyzed.In calculating of the averaged heat transfer coefficient of the whole channel, the traditional method shows significant deviation and the micro segment weighted average method is adopted. The pressure drop can mainly be affected by the mass flux and pressure and little affected by the wall heat flux. The peak of the convective heat transfer coefficient can only form at high mass flux, low wall heat flux, and near critical pressure, in which condition the nucleate-boiling-like state is easier to appear. Moreover,heat transfer deterioration will always appear, since the supercritical flow will finally develop into a filmboiling-like state. So heat transfer deterioration should be taken seriously in the design and safe operation of vaporizer PCHE. The study of this work clarified the local heat transfer and flow feature of supercritical methane in microchannel and contributed to the deep understanding of supercritical methane flow of the vaporization process in PCHE.
基金Supported by the National Natural Science Foundation of China Project(52274014)Comprehensive Scientific Research Project of China National Offshore Oil Corporation(KJZH-2023-2303)。
文摘Deep coal seams show low permeability,low elastic modulus,high Poisson’s ratio,strong plasticity,high fracture initiation pressure,difficulty in fracture extension,and difficulty in proppants addition.We proposed the concept of large-scale stimulation by fracture network,balanced propagation and effective support of fracture network in fracturing design and developed the extreme massive hydraulic fracturing technique for deep coalbed methane(CBM)horizontal wells.This technique involves massive injection with high pumping rate+high-intensity proppant injection+perforation with equal apertures and limited flow+temporary plugging and diverting fractures+slick water with integrated variable viscosity+graded proppants with multiple sizes.The technique was applied in the pioneering test of a multi-stage fracturing horizontal well in deep CBM of Linxing Block,eastern margin of the Ordos Basin.The injection flow rate is 18 m^(3)/min,proppant intensity is 2.1 m^(3)/m,and fracturing fluid intensity is 16.5 m^(3)/m.After fracturing,a complex fracture network was formed,with an average fracture length of 205 m.The stimulated reservoir volume was 1987×10^(4)m^(3),and the peak gas production rate reached 6.0×10^(4)m^(3)/d,which achieved efficient development of deep CBM.
文摘In the pursuit of global net zero carbon emissions and climate change mitigation,ongoing research into sustainable energy sources and emission control is paramount.This review examines methane leakage from abandoned oil and gas(AOG)wells,focusing particularly on Lubbock,a geographic area situated within the larger region known as the Permian Basin in West Texas,United States.The objective is to assess the extent and environmental implications of methane leakage from these wells.The analysis integrates pertinent literature,governmental and industry data,and prior Lubbock reports.Factors affecting methane leakage,including well integrity,geological characteristics,and human activities,are explored.Our research estimates 1781 drilled wells in Lubbock,forming a foundation for targeted assessments and monitoring due to historical drilling trends.The hierarchy of well statuses in Lubbock highlights the prevalence of“active oil wells,”trailed by“plugged and abandoned oil wells”and“inactive oil wells.”Methane leakage potential aligns with these well types,underscoring the importance of strategic monitoring and mitigation.The analysis notes a zenith in“drilled and completed”wells during 1980-1990.While our study's case analysis and literature review reiterate the critical significance of assessing and mitigating methane emissions from AOG wells,it's important to clarify that the research does not directly provide methane leakage data.Instead,it contextualizes the issue's magnitude and emphasizes the well type and status analysis's role in targeted mitigation efforts.In summary,our research deepens our understanding of methane leakage,aiding informed decision-making and policy formulation for environmental preservation.By clarifying well type implications and historical drilling patterns,we aim to contribute to effective strategies in mitigating methane emissions from AOG wells.
文摘On 4 March 2024,a new methane-observing satellite,MethaneSAT,was launched atop a SpaceX Falcon 9 rocket and successfully placed in orbit[1].Developed by the New York City,NY,USA-headquartered Environmental Defense Fund(EDF)in partnership with the New Zealand Space Agency and funded by multiple philanthropic donors including the Bezos Earth Fund,the spacecraft promises to greatly improve scientists’ability to pinpoint and monitor methane emissions,particularly those related to the oil and gas industry.
文摘Plasma catalysis has recently gained increased attention for its application in gas conversion,notably in processes like the dry reforming of methane aimed at transforming them into valuable chemicals and fuels.As this field is still in its early developmental stages,there is a crucial necessity to explore the synergistic mechanism between plasma and catalysts.The optimization of catalysts is imperative to improve their selectivity and conversion rates for desired products in a plasma environment.Additionally,delving into microscale investigations of plasma characteristics,such as electron temperature and the density of energetic species,is essential to enhance the stability and activity of catalysts.This review examines recent advancements in various methane conversion techniques,encompassing Dry Reforming of Methane,Steam Methane Reforming,Pa rtial Oxidation of Metha ne,and Methane Decomposition utilizing non-thermal dielectric barrier discharge(DBD)plasma.The aim is to gain a deeper understanding of plasma-catalyst interactions and to refine catalyst selection strategies for maximizing the production of desired products such as syngas,oxygenates,or higher hydrocarbons.The review delves into the catalytic mechanisms that delineate the synergistic effects between DBD plasma and catalyst in each technology,shedding light on the role of diverse catalytic properties in activating methane molecules-a pivotal step in hybrid plasma-catalytic reactions.Various approaches employed by researchers in exploring suitable catalysts and optimal reaction conditions to bolster CH_(4) conversion rates and selectivity using DBD plasma are discussed.Additionally,the review identifies gaps in the realm of plasma catalysis,underscoring the necessity for further research to fully understand the underlying principles of plasma and catalyst which are not trivial to uncover.
基金National Natural Science Foundation of China(52174279)Analysis and Testing Foundation of Kunming University of Science and Technology(2022M20202202138)Yunnan Fundamental Research Projects(202301AU070027).
文摘The challenges posed by energy and environmental issues have forced mankind to explore and utilize unconventional energy sources.It is imperative to convert the abundant coalbed gas(CBG)into high value-added products,i.e.,selective and efficient conversion of methane from CBG.Methane activation,known as the“holy grail”,poses a challenge to the design and development of catalysts.The structural complexity of the active metal on the carrier is of particular concern.In this work,we have studied the nucleation growth of small Co clusters(up to Co_(6))on the surface of CeO_(2)(110)using density functional theory,from which a stable loaded Co/CeO_(2)(110)structure was selected to investigate the methane activation mechanism.Despite the relatively small size of the selected Co clusters,the obtained Co_(x)/CeO_(2)(110)exhibits interesting properties.The optimized Co_(5)/CeO_(2)(110)structure was selected as the optimal structure to study the activation mechanism of methane due to its competitive electronic structure,adsorption energy and binding energy.The energy barriers for the stepwise dissociation of methane to form CH3^(*),CH2^(*),CH^(*),and C^(*)radical fragments are 0.44,0.55,0.31,and 1.20 eV,respectively,indicating that CH^(*)dissociative dehydrogenation is the rate-determining step for the system under investigation here.This fundamental study of metal-support interactions based on Co growth on the CeO_(2)(110)surface contributes to the understanding of the essence of Co/CeO_(2) catalysts with promising catalytic behavior.It provides theoretical guidance for better designing the optimal Co/CeO_(2) catalyst for tailored catalytic reactions.
基金supported by the National Natural Science Foundation of China(21978092).
文摘Co-combustion of methane(CH4)and acid gas(AG)is required to sustain the temperature in Claus reaction furnace.In this study,oxy-fuel combustion of methane and acid gas has been experimentally studied in a diffusion flame.Three equivalence ratios(ER=1.0,1.5,2.0)and CH_(4)-addition ratios(CH_(4)/AG=0.3,0.5,0.7)were examined and the flame was interpreted by analyzing the distributions of the temperature and species concentration along central axial.CH_(4)-AG diffusion flame could be classified into three sections namely initial reaction,oxidation and complex reaction sections.Competitive oxidation of CH_(4)and H_(2)S was noted in the first section wherein H_(2)S was preferred and both were mainly proceeding decomposition and partial oxidation.SO_(2)was formed at oxidation section together with obvious presence of H2 and CO.However,H2 and CO were inclined to be sustained under fuel rich condition in the complex reaction section.Reducing ER and increasing CH4/AG contributed to higher temperature,H_(2)S and CH_(4)oxidation and CO_(2)reactivity.Hence a growing trend for CH_(4)and AG to convert into H_(2),CO and SO_(2)could be witnessed.And this factor enhanced the generation of CS2 and COS in the flame inner core by interactions of CH4 and CO_(2)with sulfur species.COS was formed through the interactions of CO and CO_(2)with sulfur species.The CS_(2)production directly relied on reaction of CH_(4)with sulfur species.The concentration of COS was greater than CS_(2)since CS_(2)was probably inhibited due to the presence of H_(2).COS and CS_(2)could be consumed by further oxidation or other complex reactions.
基金supported by the Improvement of Green Rice Plant Type Using Genetic Information Program, Rural Development Administration, Korea (Grant No. PJ01699202)
文摘Anthropogenic methane emissions are a leading cause of the increase in global averagetemperatures,often referred to as global warming.Flooded soils play a significant role in methaneproduction,where the anaerobic conditions promote the production of methane by methanogenicmicroorganisms.Rice fields contribute a considerable portion of agricultural methane emissions,as riceplants provide both factors that enhance and limit methane production.Rice plants harbor both methaneproducingand methane-oxidizing microorganisms.Exudates from rice roots provide source for methaneproduction,while oxygen delivered from the root aerenchyma enhances methane oxidation.Studies haveshown that the diversity of these microorganisms depends on rice cultivars with some genes characterizedas harboring specific groups of microorganisms related to methane emissions.However,there is still aneed for research to determine the balance between methane production and oxidation,as rice plantspossess the ability to regulate net methane production.Various agronomical practices,such as fertilizerand water management,have been employed to mitigate methane emissions.Nevertheless,studiescorrelating agronomic and chemical management of methane with productivity are limited.Moreover,evidences for breeding low-methane-emitting rice varieties are scattered largely due to the absence ofcoordinated breeding programs.Research has indicated that phenotypic characteristics,such as rootbiomass,shoot architecture,and aerenchyma,are highly correlated with methane emissions.This reviewdiscusses available studies that involve the correlation between plant characteristics and methaneemissions.It emphasizes the necessity and importance of breeding low-methane-emitting rice varieties inaddition to existing agronomic,biological,and chemical practices.The review also delves into the idealphenotypic and physiological characteristics of low-methane-emitting rice and potential breeding techniques,drawing from studies conducted with diverse varieties,mutants,and transgenic plants.
基金supported by the National Natural Science Foundation of China(52164015)the Technology Funding Projects of Guizhou Province([2022]231).
文摘The rich accumulation of methane(CH_(4))in tectonic coal layers poses a significant obstacle to the safe and efficient extraction of coal seams and coalbed methane.Tectonic coal samples from three geologically complex regions were selected,and the main results obtained by using a variety of research tools,such as physical tests,theoretical analyses,and numerical simulations,are as follows:22.4–62.5 nm is the joint segment of pore volume,and 26.7–100.7 nm is the joint segment of pore specific surface area.In the dynamic gas production process of tectonic coal pore structure,the adsorption method of methane molecules is“solid–liquid adsorption is the mainstay,and solid–gas adsorption coexists”.Methane stored in micropores with a pore size smaller than the jointed range is defined as solid-state pores.Pores within the jointed range,which transition from micropore filling to surface adsorption,are defined as gaseous pores.Pores outside the jointed range,where solid–liquid adsorption occurs,are defined as liquid pores.The evolution of pore structure affects the methane adsorption mode,which provides basic theoretical guidance for the development of coal seam resources.
基金This project received funding from the European Union’s Horizon 2020 research and innovation program under the Marie Sklodowska-Curie grant agreement No. 813393the funding from the National Natural Science Foundation of China (No. 52177149)
文摘This study investigates the dry reformation of methane(DRM)over Ni/Al_(2)O_(3)catalysts in a dielectric barrier discharge(DBD)non-thermal plasma reactor.A novel hybrid machine learning(ML)model is developed to optimize the plasma-catalytic DRM reaction with limited experimental data.To address the non-linear and complex nature of the plasma-catalytic DRM process,the hybrid ML model integrates three well-established algorithms:regression trees,support vector regression,and artificial neural networks.A genetic algorithm(GA)is then used to optimize the hyperparameters of each algorithm within the hybrid ML model.The ML model achieved excellent agreement with the experimental data,demonstrating its efficacy in accurately predicting and optimizing the DRM process.The model was subsequently used to investigate the impact of various operating parameters on the plasma-catalytic DRM performance.We found that the optimal discharge power(20 W),CO_(2)/CH_(4)molar ratio(1.5),and Ni loading(7.8 wt%)resulted in the maximum energy yield at a total flow rate of∼51 mL/min.Furthermore,we investigated the relative significance of each operating parameter on the performance of the plasma-catalytic DRM process.The results show that the total flow rate had the greatest influence on the conversion,with a significance exceeding 35%for each output,while the Ni loading had the least impact on the overall reaction performance.This hybrid model demonstrates a remarkable ability to extract valuable insights from limited datasets,enabling the development and optimization of more efficient and selective plasma-catalytic chemical processes.
基金The project was supported by the National Key R&D Program of China(2021YFF0500702)Natural Science Foundation of Shanghai(22JC1404200)+3 种基金Program of Shanghai Academic/Technology Research Leader(20XD1404000)Natural Science Foundation of China(U22B20136,22293023)Science and Technology Major Project of Inner Mongolia(2021ZD0042)the Youth Innovation Promotion Association of CAS。
文摘Ni/TiO_(2) catalyst is widely employed for photo-driven DRM reaction while the influence of crystal structure of TiO_(2) remains unclear.In this work,the rutile/anatase ratio in supports was successfully controlled by varying the calcination temperature of anatase-TiO_(2).Structural characterizations revealed that a distinct TiO_(x) coating on the Ni nanoparticles(NPs)was evident for Ni/TiO_(2)-700 catalyst due to strong metal-support interaction.It is observed that the TiOx overlayer gradually disappeared as the ratio of rutile/anatase increased,thereby enhancing the exposure of Ni active sites.The exposed Ni sites enhanced visible light absorption and boosted the dissociation capability of CH4,which led to the much elevated catalytic activity for Ni/TiO_(2)-950 in which rutile dominated.Therefore,the catalytic activity of solar-driven DRM reaction was significantly influenced by the rutile/anatase ratio.Ni/TiO_(2)-950,characterized by a predominant rutile phase,exhibited the highest DRM reactivity,with remarkable H_(2) and CO production rates reaching as high as 87.4 and 220.2 mmol/(g·h),respectively.These rates were approximately 257 and 130 times higher,respectively,compared to those obtained on Ni/TiO_(2)-700 with anatase.This study suggests that the optimization of crystal structure of TiO_(2) support can effectively enhance the performance of photothermal DRM reaction.
基金supported by the National Natural Science Foundation of China(Nos.42272195 and 42130802)supported by the Key Applied Science and Technology Project of PetroChina(No.2023ZZ18)the Major Science and Technology Project of Changqing Oilfield(No.2023DZZ01).
文摘Deep coalbed methane(DCBM),an unconventional gas reservoir,has undergone significant advancements in recent years,sparking a growing interest in assessing pore pressure dynamics within these reservoirs.While some production data analysis techniques have been adapted from conventional oil and gas wells,there remains a gap in the understanding of pore pressure generation and evolution,particularly in wells subjected to large-scale hydraulic fracturing.To address this gap,a novel technique called excess pore pressure analysis(EPPA)has been introduced to the coal seam gas industry for the first time to our knowledge,which employs dual-phase flow principles based on consolidation theory.This technique focuses on the generation and dissipation for excess pore-water pressure(EPWP)and excess pore-gas pressure(EPGP)in stimulated deep coal reservoirs.Equations have been developed respectively and numerical solutions have been provided using the finite element method(FEM).Application of this model to a representative field example reveals that excess pore pressure arises from rapid loading,with overburden weight transferred under undrained condition due to intense hydraulic fracturing,which significantly redistributes the weight-bearing role from the solid coal structure to the injected fluid and liberated gas within artificial pores over a brief timespan.Furthermore,field application indicates that the dissipation of EPWP and EPGP can be actually considered as the process of well production,where methane and water are extracted from deep coalbed methane wells,leading to consolidation for the artificial reservoirs.Moreover,history matching results demonstrate that the excess-pressure model established in this study provides a better explanation for the declining trends observed in both gas and water production curves,compared to conventional practices in coalbed methane reservoir engineering and petroleum engineering.This research not only enhances the understanding of DCBM reservoir behavior but also offers insights applicable to production analysis in other unconventional resources reliant on hydraulic fracturing.
基金jointly supported by the Science and Technology Department of Shanxi Province,China (20201101003)the National Natural Science Foundation of China (U1810201)the China Scholarship Council (202206400012)。
文摘Methane adsorption is a critical assessment of the gas storage capacity(GSC)of shales with geological conditions.Although the related research of marine shales has been well-illustrated,the methane adsorption of marine-continental transitional(MCT)shales is still ambiguous.In this study,a method of combining experimental data with analytical models was used to investigate the methane adsorption characteristics and GSC of MCT shales collected from the Qinshui Basin,China.The Ono-Kondo model was used to fit the adsorption data to obtain the adsorption parameters.Subsequently,the geological model of GSC based on pore evolution was constructed using a representative shale sample with a total organic carbon(TOC)content of 1.71%,and the effects of reservoir pressure coefficient and water saturation on GSC were explored.In experimental results,compared to the composition of the MCT shale,the pore structure dominates the methane adsorption,and meanwhile,the maturity mainly governs the pore structure.Besides,maturity in the middle-eastern region of the Qinshui Basin shows a strong positive correlation with burial depth.The two parameters,micropore pore volume and non-micropore surface area,induce a good fit for the adsorption capacity data of the shale.In simulation results,the depth,pressure coefficient,and water saturation of the shale all affect the GSC.It demonstrates a promising shale gas potential of the MCT shale in a deeper block,especially with low water saturation.Specifically,the economic feasibility of shale gas could be a major consideration for the shale with a depth of<800 m and/or water saturation>60%in the Yushe-Wuxiang area.This study provides a valuable reference for the reservoir evaluation and favorable block search of MCT shale gas.
基金financially supported by the National Natural Science Foundation of China(No.12174092,21902046,U21A20500)Overseas Expertise Introduction Center for Discipline Innovation(D18025)+1 种基金Hubei Provincial Department of Science and Technology(No.2019CFA079)Wuhan Science and Technology Bureau(2020010601012163)
文摘Development of metal oxide semiconductors-based methane sensors with good response and low power consumption is one of the major challenges to realize the real-time monitoring of methane leakage.In this work,a self-assembled mulberry-like ZnO/SnO_(2)hierarchical structure is constructed by a two-step hydrothermal method.The resultant sensor works at room temperature with excellent response of~56.1%to 2000 ppm CH_(4)at 55%relative humidity.It is found that the strain induced at the ZnO/SnO_(2)interface greatly enhances the piezoelectric polarization on the ZnO surface and that the band bending results in the accumulation of chemically adsorbed O_(2)^(-)ions close to the interface,leading to significant improvement in the sensing performance of the methane gas sensor at room temperature.
基金supported by National Natural Science Foundation of China (Nos. 22274039 and 22178089)Hunan Provincial Innovation Foundation for Postgraduate (No.CX20220392)。
文摘At room temperature,the conversion of greenhouse gases into valuable chemicals using metal-free catalysts for dry reforming of methane(DRM) is quite promising and challenging.Herein,we developed a novel covalent organic porous polymer (TPE-COP) with rapid charge separation of the electron–hole pairs for DRM driven by visible light at room temperature,which can efficiently generate syngas (CO and H_(2)).Both electron donor (tris(4-aminophenyl)amine,TAPA) and acceptor (4,4',4'',4'''-((1 E,1'E,1''E,1'''E)-(ethene-1,1,2,2-tetrayltetrakis (benzene-4,1-diyl))tetrakis (ethene-2,1-diyl))tetrakis (1-(4-formylbenzyl)quinolin-1-ium),TPE-CHO) were existed in TPE-COP,in which the push–pull effect between them promoted the separation of photogenerated electron–hole,thus greatly improving the photocatalytic activity.Density functional theory (DFT) simulation results show that TPE-COP can form charge-separating species under light irradiation,leading to electrons accumulation in TPE-CHO unit and holes in TAPA,and thus efficiently initiating DRM.After 20 h illumination,the photocatalytic results show that the yields reach 1123.6 and 30.8μmol g^(-1)for CO and H_(2),respectively,which are significantly higher than those of TPE-CHO small molecules.This excellent result is mainly due to the increase of specific surface area,the enhancement of light absorption capacity,and the improvement of photoelectron-generating efficiency after the formation of COP.Overall,this work contributes to understanding the advantages of COP materials for photocatalysis and fundamentally pushes metal-free catalysts into the door of DRM field.
基金supported by the National Key Research and Development Program of China(Nos.2022YFB3504100,2022YFB3506200)the National Natural Science Foundation of China(Nos.22208373,22376217)+1 种基金the Beijing Nova Program(No.20220484215)the Science Foundation of China University of Petroleum,Beijing(No.2462023YJRC030)。
文摘It is urgent to develop catalysts with application potential for oxidative coupling of methane(OCM)at relatively lower temperature.Herein,three-dimensional ordered macro porous(3 DOM)La_(2-x)Sr_(x)Ce_(2-y)CayO_(7-δ)(A_(2)B_(2)O_(7)-type)catalysts with disordered defective cubic fluorite phased structure were successfully prepared by a colloidal crystal template method.3DOM structure promotes the accessibility of the gaseous reactants(O2and CH4)to the active sites.The co-doping of Ca and Sr ions in La_(2-x)Sr_(x)Ce_(2-y)CayO_(7-δ)catalysts improved the formation of oxygen vacancies,thereby leading to increased density of surface-active oxygen species(O_(2)^(-))for the activation of CH4and the formation of C2products(C2H6and C2H4).3DOM La_(2-x)Sr_(x)Ce_(2-y)CayO_(7-δ)catalysts exhibit high catalytic activity for OCM at low temperature.3DOM La1.7Sr0.3Ce1.7Ca0.3O7-δcatalyst with the highest density of O_(2)^(-)species exhibited the highest catalytic activity for low-temperature OCM,i.e.,its CH4conversion,selectivity and yield of C2products at 650℃are 32.2%,66.1%and 21.3%,respectively.The mechanism was proposed that the increase in surface oxygen vacancies induced by the co-doping of Ca and Sr ions boosts the key step of C-H bond breaking and C-C bond coupling in catalyzing low-temperature OCM.It is meaningful for the development of the low-temperature and high-efficient catalysts for OCM reaction in practical application.
基金funding from the European Research Council (ERC)under grant agreement no.834134 (WATUSO)VLAIO for Moonshot funding (ARCLATH,No.HBC.2019.0110 and ARCLATH2,No.HBC.2021.0254)+3 种基金supported by the Flemish Government as an international research infrastructure (I001321N)infrastructure support by Department EWI via the Hermes Fund (AH.2016.134)the Hercules Foundation (AKUL/13/21)FWO Vlaanderen for an FWO-SB fellowship。
文摘1.Challenges circular methane energy systems In recent decades,methane-based energy systems have rapidly gained traction across the globe because of the increasing availability of low-cost methane production capacity.However,fossil methane production and combustion lead to large greenhouse gas emissions,contributing to climate change[1].
文摘Direct methane conversion has advantages such as low energy consumption,less processes,and being more economical.However,it is difficult to activate methane at room temperature due to the high dissociation energy of C-H bonds of methane.Additionally,the target products,such as methanol,acetic acid,and other oxygenates,are prone to overoxidation,resulting in the generation of CO_(2).Therefore,the design of catalysts with high activity and selectivity is important.
基金funded by the National Key Research and Development Program of China(2019YFA0405602)the Hefei Science Center,CAS(2020HSC-KPRD001,2021HSC-UE005)the DNL Cooperation Fund,CAS(DNL202005)。
文摘Power-to-methane(P2M)processes,by converting electricity from renewable energy to H2and then into other high value-added and energy-intense chemicals in the presence of active catalysts,have become an effective solution for energy storage.However,the fluctuating electricity from intermittent renewable energy leads to a dynamic composition of reactants for downstream methanation,which requires an excellent heterogeneous catalyst to withstand the harsh conditions.Based on these findings,the objective of this review is to classify the fundamentals and status of CO/CO_(2)methanation and identify the pathways in the presence of various catalysts for methane production.In addition,this review sheds insight into the future development and challenges of CO_(2)or CO methanation,including the deactivation mechanisms and catalyst performance under dynamically harsh conditions.Finally,we elaborated on the advantages and development prospects of P2M,and then we summarized the current stage and ongoing industrialization projects of P2M.
基金the Key Program for International S&T Cooperation Projects of China(2022YFE0130100)Central Public-interest Scientific Institution Basal Research Fund of Chinese Academy of Agricultural Sciences(Y2022GH12).
文摘Background Sustainable strategies for enteric methane(CH_(4))mitigation of dairy cows have been extensively explored to improve production performance and alleviate environmental pressure.The present study aimed to investigate the effects of dietary xylooligosaccharides(XOS)and exogenous enzyme(EXE)supplementation on milk production,nutrient digestibility,enteric CH_(4) emissions,energy utilization efficiency of lactating Jersey dairy cows.Forty-eight lactating cows were randomly assigned to one of 4 treatments:(1)control diet(CON),(2)CON with 25 g/d XOS(XOS),(3)CON with 15 g/d EXE(EXE),and(4)CON with 25 g/d XOS and 15 g/d EXE(XOS+EXE).The 60-d experimental period consisted of a 14-d adaptation period and a 46-d sampling period.The enteric CO_(2)and CH_(4) emissions and O2 consumption were measured using two GreenFeed units,which were further used to determine the energy utilization efficiency of cows.Results Compared with CON,cows fed XOS,EXE or XOS+EXE significantly(P<0.05)increased milk yield,true protein and fat concentration,and energy-corrected milk yield(ECM)/DM intake,which could be reflected by the significant improvement(P<0.05)of dietary NDF and ADF digestibility.The results showed that dietary supplementation of XOS,EXE or XOS+EXE significantly(P<0.05)reduced CH_(4) emission,CH_(4)/milk yield,and CH_(4)/ECM.Furthermore,cows fed XOS demonstrated highest(P<0.05)metabolizable energy intake,milk energy output but lowest(P<0.05)of CH_(4) energy output and CH_(4) energy output as a proportion of gross energy intake compared with the remaining treatments.Conclusions Dietary supplementary of XOS,EXE or combination of XOS and EXE contributed to the improvement of lactation performance,nutrient digestibility,and energy utilization efficiency,as well as reduction of enteric CH_(4) emissions of lactating Jersey cows.This promising mitigation method may need further research to validate its long-term effect and mode of action for dairy cows.