In the development of coalbed methane(CBM)reservoirs using multistage fractured horizontal wells,there often exist areas that are either repeatedly stimulated or completely unstimulated between fracturing stages,leadi...In the development of coalbed methane(CBM)reservoirs using multistage fractured horizontal wells,there often exist areas that are either repeatedly stimulated or completely unstimulated between fracturing stages,leading to suboptimal reservoir performance.Currently,there is no well-established method for accurately evaluating the effectiveness of such stimulation.This study introduces,for the first time,the concept of the Fracture Network Bridging Coefficient(FNBC)as a novel metric to assess stimulation performance.By quantitatively coupling the proportions of unstimulated and overstimulated volumes,the FNBC effectively characterizes the connectivity and efficiency of the fracture network.A background grid calibration method is developed to quantify the stage-controlled volume,effectively stimulated volume,unstimulated volume,and repeatedly stimulated volume among different stages of horizontal wells.Furthermore,an optimization model is constructed by taking the FNBC as the objective function and the fracturing injection rate and fluid volume as optimization variables.The Simultaneous Perturbation Stochastic Approximation(SPSA)algorithm is employed to iteratively perturb and optimize these variables,progressively improving the FNBC until the optimal displacement rate and fluid volume corresponding to the maximum FNBC are obtained.Field application in a typical CBM multistage fractured horizontal well in China demonstrates that the FNBC increased from 0.358 to 0.539(a 50.6% improvement),with the injection rate rising from 16 m^(3)/min to 24 m^(3)/min and the average fluid volume per stage increasing from 2490 m^(3) to 3192 m^(3),significantly enhancing the stimulation effectiveness.This research provides theoretical support for designing high-efficiency stimulation strategies in unconventional reservoirs under dynamic limits.展开更多
Methane’s complete catalytic oxidation process has been widely studied,but efficient catalytic oxidation of low-concentration methane(≤0.75%)remains a crucial problem in the coal chemical industry.How to prevent the...Methane’s complete catalytic oxidation process has been widely studied,but efficient catalytic oxidation of low-concentration methane(≤0.75%)remains a crucial problem in the coal chemical industry.How to prevent the sintering deactivation of the active component in Pd-based catalysts and achieve efficient and stable operation of sub-nanometer catalysts remains challenging.Here,we utilize the interaction between amine ligands and Pd nanoparticles to stabilize and encapsulate the Pd particles within the pores of a molecular sieve carrier,effectively promoting the high dispersion of Pd particles.By leveraging the low acidity,high hydrophobicity,and high hydrothermal stability of the zeolite carrier,the Pd@S-1 catalyst exhibits excellent activity and stability in the catalytic oxidation of methane at lowconcentrations.Finally,density functional theory is employed to investigate the reaction mechanism of low-concentration methane during the catalytic process.Encapsulating the active metal component in zeolite to improve catalytic activity and stability provides a theoretical basis and direction for preparing complete oxidation catalysts for low-concentration methane.展开更多
Low-concentration coal mine methane(LC-CMM),which is predominantly composed of methane,serves as a clean and low-carbon energy resource with significant potential for utilization.Utilizing LC-CMM as fuel for solid oxi...Low-concentration coal mine methane(LC-CMM),which is predominantly composed of methane,serves as a clean and low-carbon energy resource with significant potential for utilization.Utilizing LC-CMM as fuel for solid oxide fuel cells(SOFCs)represents an efficient and promising strategy for its effective utilization.However,direct application in Ni-based anodes induces carbon deposition,which severely degrades cell performance.Herein,a medium-entropy oxide Sr_(2)FeNi_(0.1)Cr_(0.3)Mn_(0.3)Mo_(0.3)O_(6−δ)(SFNCMM)was developed as an anode internal reforming catalyst.Following reduction treatment,FeNi_(3) nano-alloy particles precipitate on the surface of the material,thereby significantly enhancing its catalytic activity for LC-CMM reforming process.The catalyst achieved a methane conversion rate of 53.3%,demonstrating excellent catalytic performance.Electrochemical evaluations revealed that SFNCMM-Gd_(0.1)Ce_(0.9)O_(2−δ)(GDC)with a weight ratio of 7:3 exhibited superior electrochemical performance when employed as the anodic catalytic layer.With H_(2) and LC-CMM as fuels,the single cell achieved maximum power densities of 1467.32 and 1116.97 mW·cm^(−2) at 800℃,respectively,with corresponding polarization impedances of 0.17 and 1.35Ω·cm^(2).Furthermore,the single cell maintained stable operation for over 100 h under LC-CMM fueling without significant carbon deposition,confirming its robust resistance to carbon formation.These results underscore the potential of medium-entropy oxides as highly effective catalytic layers for mitigating carbon deposition in SOFCs.展开更多
Cutting farming-related methane emissions from ruminants is critical in the battle against climate change.Since scientists initially investigated the potential of marine macroalgae to reduce methane emissions,using se...Cutting farming-related methane emissions from ruminants is critical in the battle against climate change.Since scientists initially investigated the potential of marine macroalgae to reduce methane emissions,using seaweeds as an anti-methanogenic feed additive has become prevailing in recent years.Asparagopsis taxiformis is the preferred species because it contains a relatively higher concentration of bromoform.As a type of halogenated methane analogue,bromoform contained in A.taxiformis can specifically inhibit the activity of coenzyme M methyltransferase,thereby blocking the ruminal methanogenesis.However,bromoform is a potential toxin and ozone-depleting substance.In response,current research focuses on the effects of bromoform-enriched seaweed supplementation on ruminant productivity and safety,as well as the impact of large-scale cultivation of seaweeds on the atmospheric environment.The current research on seaweed still needs to be improved,especially in developing more species with low bromoform content,such as Bonnemaisonia hamifera,Dictyota bartayresii,and Cystoseira trinodis.Otherwise,seaweed is rich in bioactive substances and exhibits antibacterial,anti-inflammatory,and other physiological properties,but research on the role of these bioactive compounds in methane emissions is lacking.It is worthy of deeper investigation to identify more potential bioactive compounds.As a new focus of attention,seaweed has attracted the interest of many scientists.Nevertheless,seaweed still faces some challenges as a feed additive to ruminants,such as the residues of heavy metals(iodine and bromine)and bromoform in milk or meat,as well as the establishment of a supply chain for seaweed cultivation,preservation,and processing.We have concluded that the methane-reducing efficacy of seaweed is indisputable.However,its application as a commercial feed additive is still influenced by factors such as safety,costs,policy incentives,and regulations.展开更多
Natural gas hydrates widely accumulate in submarine sediments composed of clay minerals.However,due to the complex physiochemistry and micron-sized particles of clay minerals,their effects on methane hydrate(MH)format...Natural gas hydrates widely accumulate in submarine sediments composed of clay minerals.However,due to the complex physiochemistry and micron-sized particles of clay minerals,their effects on methane hydrate(MH)formation and dissociation are still in controversy.In this study,montmorillonite and illite were separately mixed with quartz sand to investigate their effects on MH formation and dissociation.The microstructure of synthesized samples was observed by cryo-SEM innovatively to understand the effects of montmorillonite and illite on MH phase transition in micron scale.Results show that montmorillonite and illite both show the inhibition on MH formation kinetics and water-to-hydrate conversion,and illite shows a stronger inhibition.The 10 wt%montmorillonite addition significantly retards MH formation rate,and the 20 wt%montmorillonite has a less inhibition on the rate.The increase of illite mass ratio(0-20 wt%)retards the rate of MH formation.As the content of clay minerals increase,the water-to-hydrate conversion decreases.Cryo-SEM images presented that montmorillonite aggregates separate as individual clusters while illite particles pack as face-to-face configuration under the interaction with water.The surface-overlapped illite aggregates would make sediments pack tightly,hinder the contact between gas and water,and result in the more significant inhibition on MH formation kinetics.Under the depressurization method,the addition of clay minerals facilitates MH dissociation rate.Physicochemical properties of clay minerals and MH distribution in the pore space lead to the faster dissociation rate in clay-containing sediments.The results of this study would provide beneficial guides on geological investigations and optimizing strategies of natural gas production in marine hydrate-bearing sediments.展开更多
Yaks are well-adapted to the harsh environment of the Tibetan Plateau,and they emit less enteric methane(CH_(4))and digest poor-quality forage better than cattle.To examine the potential of yak rumen inoculum to mitig...Yaks are well-adapted to the harsh environment of the Tibetan Plateau,and they emit less enteric methane(CH_(4))and digest poor-quality forage better than cattle.To examine the potential of yak rumen inoculum to mitigate CH_(4)production and improve digestibility in cattle,we incubated substrate with rumen inoculum from yak(YRI)and cattle(CRI)in vitro in five ratios(YRI:CRI):(1)0:100(control),(2)25:75,(3)50:50,(4)75:25 and(5)100:0 for 72 h.The YRI:CRI ratios of 50:50,75:25 and 100:0 produced less total gas and CH_(4)and accumulated less hydrogen(H_(2))than0:100(control)at most time points.From 12 h onwards,there was a linear decrease(P<0.05)in carbon dioxide(CO_(2))production with increasing YRI:CRI ratio.At 72 h,the ratios of 50:50 and 75:25 had higher dry matter(+7.71%and+4.11%,respectively),as well as higher acid detergent fiber digestibility(+15.5%and+7.61%,respectively),when compared to the 0:100 ratio(P<0.05).Increasing the proportion of YRI generally increased total VFA concentrations,and,concomitantly,decreased the proportion of metabolic hydrogen([2H])incorporated into CH_(4),and decreased the recovery of[2H].The lower[2H]recovery indicates unknown[2H]sinks in the culture.Estimated Gibbs free energy changes(ΔG)for reductive acetogenesis were negative,indicating the thermodynamic feasibility of this process.It would be beneficial to identify:1)the alternative[2H]sinks,which could help mitigate CH_(4)emission,and 2)core microbes involved in fiber digestion.This experiment supported lower CH_(4)emission and greater nutrient digestibility of yaks compared to cattle.Multi-omics combined with microbial culture technologies developed in recent years could help to better understand fermentation differences among species.展开更多
Methane contributes to global warming,and livestock is one of the sources of methane production.However,methane emission studies using bibliometric tools in livestock are lacking.Given the negative impact of climate c...Methane contributes to global warming,and livestock is one of the sources of methane production.However,methane emission studies using bibliometric tools in livestock are lacking.Given the negative impact of climate change on the ecosystem and the rise in methane emissions,it is essential to conduct a bibliometrics study to provide an overview and research trends.We used the Bibliometrix package and VOSviewer to decipher bibliometric indices for methane emissions in cattle farms(MECF).Current dataset were collected from the Web of Science(Core Collection)database,and 8,998 publications were analyzed.The most co-occurring keywords scientists preferred were methane(1,528),greenhouse gas(443),methane emissions(440),and cattle(369).Methane was the most frequently used keyword in the published scientific literature.Thematic evolution of research themes and trend results highlighted carbon dioxide,methane,dairy cattle,cattle,and risk factors during 1999–2017.Chinese Academy of Sciences ranked on top with 485 publications,followed by Agriculture&Agri-Food Canada,University of Colorado,National Oceanic and Atmospheric Administration,and Aarhus University.Chinese Academy of Sciences was also the most cited organization,followed by the University of Colorado,Agriculture&Agri-Food Canada,National Oceanic and Atmospheric Administration,and United States Geological Survey.Source analysis showed that the Science of the Total Environment was cited with the highest total link strength.Science of the Total Environment ranked first in source core 1 with 290 citation frequencies,followed by Journal of Dairy Science with 223 citation frequencies.Currently,no bibliometric study has been conducted on MECF,and to fill this knowledge gap,we carried out this study to highlight methane emissions in cattle farms,aiming at a climate change perspective.In this regard,we focused on the research productivity of countries authors,journals and institutions,co-occurrence of keywords,evolution of research trends,and collaborative networking.Based on relevance degree of centrality,methane emissions and greenhouse gases appeared as basic themes,cattle,and dairy cattle appeared as emerging/declining themes,whereas,methane,greenhouse gas and nitrous oxide appeared to fall amongst basic and motor themes.On the other hand,beef cattle,rumen and dairy cow seem to be between motor and niche themes,and risk factors lie in niche themes.The present bibliometric analysis provides research progress on methane emissions in cattle farms.Current findings may provide a framework for understanding research trends and themes in MECF research.展开更多
As a major contributor to methane production in agriculture,there is a need for a suitable methane inhibitor to reduce ruminant methane emissions and minimize the impact on the climate.This work aimed to explore the i...As a major contributor to methane production in agriculture,there is a need for a suitable methane inhibitor to reduce ruminant methane emissions and minimize the impact on the climate.This work aimed to explore the influence of cordycepin on rumen fermentation,gas production,microbiome and their metabolites.A total of 0.00,0.08,0.16,0.32,and 0.64 g L^(–1)cordycepin were added into fermentation bottles containing 2 g total mixed ration for in vitro ruminal fermentation,and then the gas produced and fermentation parameters were measured for each bottle.Samples from the 0 and 0.64 g L^(–1)cordycepin addition were selected for 16S rRNA gene sequencing and metabolome analysis.The result of this experiment indicated that the addition of cordycepin could linearly increase the concentration of total volatile fatty acid,ammonia nitrogen,the proportion of propionate,valerate,and isovalerate,and linearly reduce ruminal pH and methane,carbon dioxide,hydrogen and total gas production,as well as the methane proportion,carbon dioxide proportion and proportion of butyrate.In addition,there was a quadratic relationship between hydrogen and cordycepin addition.At the same time,the relative abundance of Succiniclasticum,Prevotella,Rikenellaceae_RC9_gut_group,NK4A214_group,Christensenellaceae_R_(7)_group,unclassified_F082,Veillonellaceae_UCG_001,Dasytricha,Ophryoscolex,Isotricha,unclassified_Eukaryota,Methanobrevibacter,and Piromyces decreased significantly after adding the maximum dose of cordycepin.In contrast,the relative abundance of Succinivibrio,unclassified_Succinivibrionaceae,Prevotellaceae_UCG_001,unclassified_Lachnospiraceae,Lachnospira,Succinivibrionaceae_UCG_002,Pseudobutyrivibrio,Entodinium,Polyplastron,unclassified_Methanomethylophilaceae,Methanosphaera,and Candidatus_Methanomethylophilus increased significantly.Metabolic pathways such as biosynthesis of unsaturated fatty acids and purine metabolism and metabolites such as arachidonic acid,adenine,and 2′-deoxyguanosine were also affected by the addition of cordycepin.Based on this,we conclude that cordycepin is an effective methane emission inhibitor that can change the rumen metabolites and fermentation parameters by influencing the rumen microbiome,thus regulating rumen methane production.This experiment may provide a potential theoretical reference for developing Cordyceps byproduct or additives containing cordycepin as methane inhibitors.展开更多
Developing deep fragmented soft coalbed methane(CBM)can significantly enhance domestic natural gas supplies,reduce reliance on imported energy,and bolster national energy security.This manuscript provides a comprehens...Developing deep fragmented soft coalbed methane(CBM)can significantly enhance domestic natural gas supplies,reduce reliance on imported energy,and bolster national energy security.This manuscript provides a comprehensive review of commonly employed coalbed methane extraction technologies.It then delves into several critical issues in the current stage of CBM exploration and development in China,including the compatibility of existing technologies with CBM reservoirs,the characteristics and occurrence states of CBM reservoirs,critical desorption pressure,and gas generation mechanisms.Our research indicates that current CBM exploration and development technologies in China have reached an internationally advanced level,yet the industry is facing unprecedented challenges.Despite progress in low-permeability,high-value coal seams,significant breakthroughs have not been achieved in exploring other types of coal seams.For different coal reservoirs,integrated extraction technologies have been developed,such as surface pre-depressurisation and segmented hydraulic fracturing of coal seam roof strata.Additionally,techniques like large-scale volume fracturing in horizontal wells have been established,significantly enhancing reservoir stimulation effects and coalbed methane recovery rates.However,all of these technologies are fundamentally based on permeation.These technologies lack direct methods aimed at enhancing the diffusion rate of CBM,thereby failing to fully reflect the unique characteristics of CBM.Current CBM exploration and development theories and technologies are not universally applicable to all coal seams.They do not adequately account for the predominantly adsorbed state of CBM,and the complex and variable gas generation mechanisms further constrain CBM development in China.Finally,continuous exploration of new deep CBM exploration technologies is necessary.Integrating more effective reservoir stimulation technologies is essential to enhance technical adaptability concerning CBM reservoir characteristics,gas occurrence states,and gas generation mechanisms,ultimately achieving efficient CBM development.We conclude that while China possesses a substantial foundation of deep fractured CBM resources,industry development is constrained and requires continuous exploration of new CBM exploration and development technologies to utilize these resources effectively.展开更多
Methane(CH4),the predominant component of natural gas and shale gas,is regarded as a promising carbon feedstock for chemical synthesis[1].However,considering the extreme stability of CH4 molecules,it's quite chall...Methane(CH4),the predominant component of natural gas and shale gas,is regarded as a promising carbon feedstock for chemical synthesis[1].However,considering the extreme stability of CH4 molecules,it's quite challenging in simultaneously achieving high activity and selectivity for target products under mild conditions,especially when synthesizing high-value C2t chemicals such as ethanol[2].The conversion of methane to ethanol by photocatalysis is promising for achieving transformation under ambient temperature and pressure conditions.Currently,the apparent quantum efficiency(AQE)of solar-driven methane-to-ethanol conversion is generally below 0.5%[3,4].Furthermore,the stability of photocatalysts remains inadequate,offering substantial potential for further improvement.展开更多
Recent research progress on the use of Ni-based catalysts supported by various carbon materials,such as carbon nanotubes,graphene,and activated carbon,for the hydrogenation of CO_(2)to CH4 is summarized.The influence ...Recent research progress on the use of Ni-based catalysts supported by various carbon materials,such as carbon nanotubes,graphene,and activated carbon,for the hydrogenation of CO_(2)to CH4 is summarized.The influence of additives and surface modification methods on improving their catalytic performance is discussed as is the reaction mechanism,especially the structurefunction relationship produced by the carbon.The review provides a comprehensive directory for the rational design of carbon-supported Ni-based catalysts for the methanation of CO_(2).展开更多
CeO_(2) based semiconductor are widely used in solar-driven photothermal catalytic dry reforming of methane(DRM)reaction,but still suffer from low activity and low light utilization efficiency.This study developed gra...CeO_(2) based semiconductor are widely used in solar-driven photothermal catalytic dry reforming of methane(DRM)reaction,but still suffer from low activity and low light utilization efficiency.This study developed graphite-CeO_(2) interfaces to enhance solar-driven photothermal catalytic DRM.Compared with carbon nanotubes-modified CeO_(2)(CeO_(2)-CNT),graphite-modified CeO_(2)(CeO_(2)-GRA)constructed graphite-CeO_(2) interfaces with distortion in CeO_(2),leading to the formation abundant oxygen vacancies.These graphite-CeO_(2) interfaces with oxygen vacancies enhanced optical absorption and promoted the generation and separation of photogenerated carriers.The high endothermic capacity of graphite elevated the catalyst surface temperature from 592.1−691.3℃,boosting light-to-thermal conversion.The synergy between photogenerated carriers and localized heat enabled Ni/CeO_(2)-GRA to achieve a CO production rate of 9985.6 mmol/(g·h)(vs 7192.4 mmol/(g·h)for Ni/CeO_(2))and a light-to-fuel efficiency of 21.8%(vs 13.8%for Ni/CeO_(2)).This work provides insights for designing graphite-semiconductor interfaces to advance photothermal catalytic efficiency.展开更多
Based on the coalbed methane(CBM)/coal-rock gas(CRG)geological,geophysical,and experimental testing data from the Daji block in the Ordos Basin,the coal-forming and hydrocarbon generation&accumulation characterist...Based on the coalbed methane(CBM)/coal-rock gas(CRG)geological,geophysical,and experimental testing data from the Daji block in the Ordos Basin,the coal-forming and hydrocarbon generation&accumulation characteristics across different zones were dissected,and the key factors controlling the differential CBM/CRG enrichment were identified.The No.8 coal seam of the Carboniferous Benxi Formation in the Daji block is 8-10 m thick,typically overlain by limestone.The primary hydrocarbon generation phase occurred during the Early Cretaceous.Based on the differences in tectonic evolution and CRG occurrence,and with the maximum vitrinite reflectance of 2.0%and burial depth of 1800 m as boundaries,the study area is divided into deeply buried and deeply preserved,deeply buried and shallowly preserved,and shallowly buried and shallowly preserved zones.The deeply buried and deeply preserved zone contains gas content of 22-35 m^(3)/t,adsorbed gas saturation of 95%-100%,and formation water with total dissolved solid(TDS)higher than 50000 mg/L.This zone features structural stability and strong sealing capacity,with high gas production rates.The deeply buried and shallowly preserved zone contains gas content of 16-20 m^(3)/t,adsorbed gas saturation of 80%-95%,and formation water with TDS of 5000-50000 mg/L.This zone exhibits localized structural modification and hydrodynamic sealing,with moderate gas production rate.The shallowly buried and shallowly preserved zone contains gas content of 8-16 m^(3)/t,adsorbed gas saturation of 50%-70%,and formation water with TDS lower than 5000 mg/L.This zone experienced intense uplift,resulting in poor sealing and secondary alteration of the primary gas reservoir,with partial adsorbed gas loss,and low gas production rate.A depositional unification and structural divergence model is proposed,that is,although coal seams across the basin experienced broadly similar depositional and tectonic histories,differences in tectonic intensity have led to spatial heterogeneity in the maximum burial depth(i.e.,thermal maturity of coal)and current burial depth and occurrence of CRG(i.e.,gas content and occurrence state).The research results provide valuable guidance for advancing the theoretical understanding of CBM/CRG enrichment and for improving exploration and development practices.展开更多
The objective of this study is to propose an optimal plant design for blue hydrogen production aboard a liquefiednatural gas(LNG)carrier.This investigation focuses on integrating two distinct processes—steam methaner...The objective of this study is to propose an optimal plant design for blue hydrogen production aboard a liquefiednatural gas(LNG)carrier.This investigation focuses on integrating two distinct processes—steam methanereforming(SMR)and ship-based carbon capture(SBCC).The first refers to the common practice used to obtainhydrogen from methane(often derived from natural gas),where steam reacts with methane to produce hydrogenand carbon dioxide(CO_(2)).The second refers to capturing the CO_(2) generated during the SMR process on boardships.By capturing and storing the carbon emissions,the process significantly reduces its environmental impact,making the hydrogen production“blue,”as opposed to“grey”(which involves CO_(2) emissions without capture).For the SMR process,the analysis reveals that increasing the reformer temperature enhances both the processperformance and CO_(2) emissions.Conversely,a higher steam-to-carbon(s/c)ratio reduces hydrogen yield,therebydecreasing thermal efficiency.The study also shows that preheating the air and boil-off gas(BOG)before theyenter the combustion chamber boosts overall efficiency and curtails CO_(2) emissions.In the SBCC process,puremonoethanolamine(MEA)is employed to capture the CO_(2) generated by the exhaust gases from the SMR process.The results indicate that with a 90%CO_(2) capture rate,the associated heat consumption amounts to 4.6 MJ perkilogram of CO_(2) captured.This combined approach offers a viable pathway to produce blue hydrogen on LNGcarriers while significantly reducing the carbon footprint.展开更多
AIM:To investigate the effect of 0.01%low-concentration atropine(LA)on quantitative contrast sensitivity function(qCSF)in children with myopia.METHODS:This paired case-control study included 90 eyes of 58 children who...AIM:To investigate the effect of 0.01%low-concentration atropine(LA)on quantitative contrast sensitivity function(qCSF)in children with myopia.METHODS:This paired case-control study included 90 eyes of 58 children who were sex-,age-,and refractionmatched and equally divided into two groups:the 0.01%LA group had undergone 6mo use of daily 0.01%atropine and control group was naïve to LA.Routine ophthalmic examinations and qCSF test without refractive correction were performed.Two groups were compared in monocular and binocular qCSF parameters,including the area under logCSF,CSF acuity,and contrast sensitivity(CS)at 1.0-18.0 cycle per degree(cpd).RESULTS:In the monocular comparison,the CSF acuity of the LA group was significantly higher than that of the control group(7.58±5.51 vs 6.37±4.22 cpd,P<0.05).The subgroup analysis showed that in the 6-9y group,CSF acuity was significantly higher in the LA group than the control group(8.76±6.19 vs 6.54±4.25 cpd,P<0.05),and in the Female group,low refraction sphere group,and high refraction cylinder group,the CS at high spatial frequencies(12.0 and 18.0 cpd)were significantly higher in the LA group than in the control group(all P<0.05).In the binocular test,CSF acuity and CS at 12.0 cpd were significantly higher in the LA group than in the control group(10.95±7.00 vs 8.65±5.12 cpd;0.17±0.33 vs 0.06±0.16,respectively;both P<0.05).CONCLUSION:Use of LA may result in improved CS in children with early onset myopia.展开更多
Methane(CH_(4))has a higher heat capacity(104.9 kcal/mol)than carbon dioxide(CO_(2)),and this has inspired research aimed at reducing methane levels to retard global warming.Hydroxylation under ambient conditions thro...Methane(CH_(4))has a higher heat capacity(104.9 kcal/mol)than carbon dioxide(CO_(2)),and this has inspired research aimed at reducing methane levels to retard global warming.Hydroxylation under ambient conditions through methanotrophs can provide crucial information for understanding the harsh C-H activation of methane.Soluble methane monooxygenase(sMMO)belongs to the bacterial multi-component monooxygenase superfamily and requires hydroxylase(MMOH),regulatory(MMOB),and reductase(MMOR)components.Recent structural and biophysical studies have demonstrated that these components accelerate and retard methane hydroxylation in MMOH through protein-protein interactions.Complex structures of sMMO,including MMOH-MMOB and MMOH-MMOD,illustrate how these regulatory and inhibitory components orchestrate the di-iron active sites located within the four-helix bundles of MMOH,specifically at the docking surface known as the canyon region.In addition,recent biophysical studies have demonstrated the role of MmoR,aσ54-dependent transcriptional regulator,in regulating sMMO expression.This perspective article introduces remarkable discoveries in recent reports on sMMO components that are crucial for understanding sMMO expression and activities.Our findings provide insight into how sMMO components interact with MMOH to control methane hydroxylation,shedding light on the mechanisms governing sMMO expression and the interactions between activating enzymes and promoters.展开更多
CO_(2)-free H_(2)refers to H_(2)production process without CO_(2)emission,which is a promising clean energy in the future.Catalytic decomposition of methane(CDM)is a competitive technology to produce CO_(2)-free H2 wi...CO_(2)-free H_(2)refers to H_(2)production process without CO_(2)emission,which is a promising clean energy in the future.Catalytic decomposition of methane(CDM)is a competitive technology to produce CO_(2)-free H2 with large-scale.However,CDM reaction is highly endothermic and is kinetically and thermodynamically unfavorable,which typically requires a harsh reaction temperature above 800℃.In this work,solar-driven photothermal catalytic decomposition of methane was firstly introduced to produce CO_(2)-free H_(2)relying solely on solar energy as the driving force.A high H_(2)yield of 204.6 mmol g^(–1)h^(–1)was observed over Ni-CeO2 interface under photothermal conditions,along with above 87%reduction in the apparent activation energy(11.2 vs.87.3 kJ mol^(–1))when comparing with the traditional thermal catalysis.Further studies suggested that Ni/CeO_(2)catalyst enhanced optical absorption in visible-infrared region to ensure the heat energy for methane decomposition.The generated electrons and holes participated in the redox process of photo-driven CDM reaction with enhanced separation ability of hot carriers excited by ultraviolet-visible light,which lowered activation energy and improved the photothermal catalytic activity.This work provides a promising photothermal catalytic strategy to produce CO_(2)-free H^(2)under mild conditions.展开更多
The conversion of the greenhouse gas methane to value-added chemicals such as alcohols is a promising technology to mitigate environmental issue and the energy crisis.Especially,the sustainable photocatalytic,electroc...The conversion of the greenhouse gas methane to value-added chemicals such as alcohols is a promising technology to mitigate environmental issue and the energy crisis.Especially,the sustainable photocatalytic,electrocatalytic and photoelectrocatalytic conversion of methane at ambient conditions is regarded as an alternative technology to replace with thermocatalysis.In this review,we summarize recent advances in photocatalytic,electrocatalytic and photoelectrocatalytic conversion of methane into alcohols.We firstly introduce the general principles of photocatalysis,electrocatalysis and photoelectrocatalysis.Then,we discuss the mechanism for selective activation of C-H bond and following oxygenation over metal,inorganic semiconductor,organic semiconductor,and heterojunction composite systems in the photocatalytic,electrocatalytic and photoelectrocatalytic methane oxidation in detail.Later,we present insights into the construction of effective photocatalyst,electrocatalyst and photoelectrocatalyst for methane conversion into alcohols from the perspective of band structures and active sites.Finally,the challenges and outlook for future designs of photocatalytic,electrocatalytic and photoelectrocatalytic methane oxidation systems are also proposed.展开更多
Introducing methane at the anode side of a solid oxide electrolysis cell(SOEC)has been proven to effectively suppress the oxygen evolution reaction(OER),thereby enabling hydrogen production at significantly lower volt...Introducing methane at the anode side of a solid oxide electrolysis cell(SOEC)has been proven to effectively suppress the oxygen evolution reaction(OER),thereby enabling hydrogen production at significantly lower voltages.In this work,a double perovskite oxide,Sr_(2)Fe_(1.4)Pt_(0.1)Mo_(0.5)O_(6-δ)(abbreviated as Pt-SFM),was successfully synthesized by a liquid-phase method and employed as both an electronic conductor and a catalyst for methane oxidation at the SOEC anode.Following high-temperature treatment under a reducing atmosphere,platinum(Pt)nanoparticles were exsolved from the perovskite lattice and uniformly dispersed on the oxide surface.These exsolved Pt nanoparticles act as highly active sites for methane adsorption and oxidation.Electrochemical performance tests were conducted at 1123.15 K,and the results demonstrated that the Pt-SFM cell treated for 20 h(Pt-SFM 20 h)achieved a current density of 0.85 A·cm^(-2)at an applied voltage of 1.40 V.This performance corresponds to a 102.4%enhancement compared to the undoped SFM 20 h cell.The superior performance is attributed to the presence of exsolved Pt,which significantly improves the catalyst's ability to adsorb and dissociate methane molecules.Electrochemical impedance spectroscopy(EIS)analysis under open-circuit conditions revealed that the polarization impedance of the Pt-SFM 20 h cell was 1.25Ω·cm^(2),which is 49.2%lower than that of the SFM 20 h cell.Furthermore,a 45-h long-term stability test showed that the Pt-SFM 20 h cell maintained a stable performance,with a low voltage degradation rate of only 0.67 mV·h^(-1).展开更多
The ocean represents a vast carbon reservoir,where methane concentrations reflect a balance between production and consumption processes.In this study,marine sediments harboring abundant aerobic methanotrophs were inc...The ocean represents a vast carbon reservoir,where methane concentrations reflect a balance between production and consumption processes.In this study,marine sediments harboring abundant aerobic methanotrophs were incubated under varying methane concentrations.We investigated changes in methane oxidation rates and the community structure of these methanotrophs during incubation.Results demonstrate that methane concentration regulates aerobic methane oxidation.The oxidation rate increased with rising methane concentration up to 50%.However,beyond this threshold,at 80%methane,the oxidation rate declined.Following incubation,the abundance of aerobic methanotrophs increased significantly,with Methylobacterium becoming the dominant genus.Relative abundances of other bacteria potentially associated with alkane degradation,including Planomicrobium,Bacillus,Methylophaga,Erythrobacter,Gillisia and Pontibacter,were also significantly enriched.These findings provide a scientific basis for predicting marine methane emission dynamics,which is crucial for assessing and mitigating the greenhouse gas impact of methane.展开更多
基金the financial support from National Natural Science Foundation of China(No.52474029)Strategic and Applied Scientific Research Project of PetroChina Company Limited(2023ZZ18,2023ZZ18YJ04).
文摘In the development of coalbed methane(CBM)reservoirs using multistage fractured horizontal wells,there often exist areas that are either repeatedly stimulated or completely unstimulated between fracturing stages,leading to suboptimal reservoir performance.Currently,there is no well-established method for accurately evaluating the effectiveness of such stimulation.This study introduces,for the first time,the concept of the Fracture Network Bridging Coefficient(FNBC)as a novel metric to assess stimulation performance.By quantitatively coupling the proportions of unstimulated and overstimulated volumes,the FNBC effectively characterizes the connectivity and efficiency of the fracture network.A background grid calibration method is developed to quantify the stage-controlled volume,effectively stimulated volume,unstimulated volume,and repeatedly stimulated volume among different stages of horizontal wells.Furthermore,an optimization model is constructed by taking the FNBC as the objective function and the fracturing injection rate and fluid volume as optimization variables.The Simultaneous Perturbation Stochastic Approximation(SPSA)algorithm is employed to iteratively perturb and optimize these variables,progressively improving the FNBC until the optimal displacement rate and fluid volume corresponding to the maximum FNBC are obtained.Field application in a typical CBM multistage fractured horizontal well in China demonstrates that the FNBC increased from 0.358 to 0.539(a 50.6% improvement),with the injection rate rising from 16 m^(3)/min to 24 m^(3)/min and the average fluid volume per stage increasing from 2490 m^(3) to 3192 m^(3),significantly enhancing the stimulation effectiveness.This research provides theoretical support for designing high-efficiency stimulation strategies in unconventional reservoirs under dynamic limits.
基金supported by the National Natural Science Foundation of China(No.52270114)the State key laboratory of coal mine disaster dynamics and control(No.2011DA105827-FW202210).
文摘Methane’s complete catalytic oxidation process has been widely studied,but efficient catalytic oxidation of low-concentration methane(≤0.75%)remains a crucial problem in the coal chemical industry.How to prevent the sintering deactivation of the active component in Pd-based catalysts and achieve efficient and stable operation of sub-nanometer catalysts remains challenging.Here,we utilize the interaction between amine ligands and Pd nanoparticles to stabilize and encapsulate the Pd particles within the pores of a molecular sieve carrier,effectively promoting the high dispersion of Pd particles.By leveraging the low acidity,high hydrophobicity,and high hydrothermal stability of the zeolite carrier,the Pd@S-1 catalyst exhibits excellent activity and stability in the catalytic oxidation of methane at lowconcentrations.Finally,density functional theory is employed to investigate the reaction mechanism of low-concentration methane during the catalytic process.Encapsulating the active metal component in zeolite to improve catalytic activity and stability provides a theoretical basis and direction for preparing complete oxidation catalysts for low-concentration methane.
基金supported by the National Key R&D Program of China(No.2024YFB4007501)the Natural Science Foundation of Jiangsu Province(No.BK20240109)the project of Jiangsu Key Laboratory for Clean Utilization of Carbon Resources(No.BM2024007).
文摘Low-concentration coal mine methane(LC-CMM),which is predominantly composed of methane,serves as a clean and low-carbon energy resource with significant potential for utilization.Utilizing LC-CMM as fuel for solid oxide fuel cells(SOFCs)represents an efficient and promising strategy for its effective utilization.However,direct application in Ni-based anodes induces carbon deposition,which severely degrades cell performance.Herein,a medium-entropy oxide Sr_(2)FeNi_(0.1)Cr_(0.3)Mn_(0.3)Mo_(0.3)O_(6−δ)(SFNCMM)was developed as an anode internal reforming catalyst.Following reduction treatment,FeNi_(3) nano-alloy particles precipitate on the surface of the material,thereby significantly enhancing its catalytic activity for LC-CMM reforming process.The catalyst achieved a methane conversion rate of 53.3%,demonstrating excellent catalytic performance.Electrochemical evaluations revealed that SFNCMM-Gd_(0.1)Ce_(0.9)O_(2−δ)(GDC)with a weight ratio of 7:3 exhibited superior electrochemical performance when employed as the anodic catalytic layer.With H_(2) and LC-CMM as fuels,the single cell achieved maximum power densities of 1467.32 and 1116.97 mW·cm^(−2) at 800℃,respectively,with corresponding polarization impedances of 0.17 and 1.35Ω·cm^(2).Furthermore,the single cell maintained stable operation for over 100 h under LC-CMM fueling without significant carbon deposition,confirming its robust resistance to carbon formation.These results underscore the potential of medium-entropy oxides as highly effective catalytic layers for mitigating carbon deposition in SOFCs.
基金supported by the Youth Innovation Program of the Chinese Academy of Agricultural Sciences(Y2022QC10)the Agricultural Science and Technology Innovation Program,China(CAAS-ASTIP-2023-IFR-03,CAAS-IFR-ZDRW202302 and CAAS-IFR-ZDRW202404)the Basal Research Fund of the Institute of Feed Research of Chinese Academy of Agricultural Sciences(1610382024009)。
文摘Cutting farming-related methane emissions from ruminants is critical in the battle against climate change.Since scientists initially investigated the potential of marine macroalgae to reduce methane emissions,using seaweeds as an anti-methanogenic feed additive has become prevailing in recent years.Asparagopsis taxiformis is the preferred species because it contains a relatively higher concentration of bromoform.As a type of halogenated methane analogue,bromoform contained in A.taxiformis can specifically inhibit the activity of coenzyme M methyltransferase,thereby blocking the ruminal methanogenesis.However,bromoform is a potential toxin and ozone-depleting substance.In response,current research focuses on the effects of bromoform-enriched seaweed supplementation on ruminant productivity and safety,as well as the impact of large-scale cultivation of seaweeds on the atmospheric environment.The current research on seaweed still needs to be improved,especially in developing more species with low bromoform content,such as Bonnemaisonia hamifera,Dictyota bartayresii,and Cystoseira trinodis.Otherwise,seaweed is rich in bioactive substances and exhibits antibacterial,anti-inflammatory,and other physiological properties,but research on the role of these bioactive compounds in methane emissions is lacking.It is worthy of deeper investigation to identify more potential bioactive compounds.As a new focus of attention,seaweed has attracted the interest of many scientists.Nevertheless,seaweed still faces some challenges as a feed additive to ruminants,such as the residues of heavy metals(iodine and bromine)and bromoform in milk or meat,as well as the establishment of a supply chain for seaweed cultivation,preservation,and processing.We have concluded that the methane-reducing efficacy of seaweed is indisputable.However,its application as a commercial feed additive is still influenced by factors such as safety,costs,policy incentives,and regulations.
基金supported by the Key Research Program of the Institute of Geology&Geophysics,CAS(Grant No.IGGCAS-201903).
文摘Natural gas hydrates widely accumulate in submarine sediments composed of clay minerals.However,due to the complex physiochemistry and micron-sized particles of clay minerals,their effects on methane hydrate(MH)formation and dissociation are still in controversy.In this study,montmorillonite and illite were separately mixed with quartz sand to investigate their effects on MH formation and dissociation.The microstructure of synthesized samples was observed by cryo-SEM innovatively to understand the effects of montmorillonite and illite on MH phase transition in micron scale.Results show that montmorillonite and illite both show the inhibition on MH formation kinetics and water-to-hydrate conversion,and illite shows a stronger inhibition.The 10 wt%montmorillonite addition significantly retards MH formation rate,and the 20 wt%montmorillonite has a less inhibition on the rate.The increase of illite mass ratio(0-20 wt%)retards the rate of MH formation.As the content of clay minerals increase,the water-to-hydrate conversion decreases.Cryo-SEM images presented that montmorillonite aggregates separate as individual clusters while illite particles pack as face-to-face configuration under the interaction with water.The surface-overlapped illite aggregates would make sediments pack tightly,hinder the contact between gas and water,and result in the more significant inhibition on MH formation kinetics.Under the depressurization method,the addition of clay minerals facilitates MH dissociation rate.Physicochemical properties of clay minerals and MH distribution in the pore space lead to the faster dissociation rate in clay-containing sediments.The results of this study would provide beneficial guides on geological investigations and optimizing strategies of natural gas production in marine hydrate-bearing sediments.
基金supported by the National Natural Science Foundation of China(32072757 and U21A20250)。
文摘Yaks are well-adapted to the harsh environment of the Tibetan Plateau,and they emit less enteric methane(CH_(4))and digest poor-quality forage better than cattle.To examine the potential of yak rumen inoculum to mitigate CH_(4)production and improve digestibility in cattle,we incubated substrate with rumen inoculum from yak(YRI)and cattle(CRI)in vitro in five ratios(YRI:CRI):(1)0:100(control),(2)25:75,(3)50:50,(4)75:25 and(5)100:0 for 72 h.The YRI:CRI ratios of 50:50,75:25 and 100:0 produced less total gas and CH_(4)and accumulated less hydrogen(H_(2))than0:100(control)at most time points.From 12 h onwards,there was a linear decrease(P<0.05)in carbon dioxide(CO_(2))production with increasing YRI:CRI ratio.At 72 h,the ratios of 50:50 and 75:25 had higher dry matter(+7.71%and+4.11%,respectively),as well as higher acid detergent fiber digestibility(+15.5%and+7.61%,respectively),when compared to the 0:100 ratio(P<0.05).Increasing the proportion of YRI generally increased total VFA concentrations,and,concomitantly,decreased the proportion of metabolic hydrogen([2H])incorporated into CH_(4),and decreased the recovery of[2H].The lower[2H]recovery indicates unknown[2H]sinks in the culture.Estimated Gibbs free energy changes(ΔG)for reductive acetogenesis were negative,indicating the thermodynamic feasibility of this process.It would be beneficial to identify:1)the alternative[2H]sinks,which could help mitigate CH_(4)emission,and 2)core microbes involved in fiber digestion.This experiment supported lower CH_(4)emission and greater nutrient digestibility of yaks compared to cattle.Multi-omics combined with microbial culture technologies developed in recent years could help to better understand fermentation differences among species.
基金supported by the Special Fund for Science and Technology Innovation Strategy of Guangdong Province,China(2022660500250009604)。
文摘Methane contributes to global warming,and livestock is one of the sources of methane production.However,methane emission studies using bibliometric tools in livestock are lacking.Given the negative impact of climate change on the ecosystem and the rise in methane emissions,it is essential to conduct a bibliometrics study to provide an overview and research trends.We used the Bibliometrix package and VOSviewer to decipher bibliometric indices for methane emissions in cattle farms(MECF).Current dataset were collected from the Web of Science(Core Collection)database,and 8,998 publications were analyzed.The most co-occurring keywords scientists preferred were methane(1,528),greenhouse gas(443),methane emissions(440),and cattle(369).Methane was the most frequently used keyword in the published scientific literature.Thematic evolution of research themes and trend results highlighted carbon dioxide,methane,dairy cattle,cattle,and risk factors during 1999–2017.Chinese Academy of Sciences ranked on top with 485 publications,followed by Agriculture&Agri-Food Canada,University of Colorado,National Oceanic and Atmospheric Administration,and Aarhus University.Chinese Academy of Sciences was also the most cited organization,followed by the University of Colorado,Agriculture&Agri-Food Canada,National Oceanic and Atmospheric Administration,and United States Geological Survey.Source analysis showed that the Science of the Total Environment was cited with the highest total link strength.Science of the Total Environment ranked first in source core 1 with 290 citation frequencies,followed by Journal of Dairy Science with 223 citation frequencies.Currently,no bibliometric study has been conducted on MECF,and to fill this knowledge gap,we carried out this study to highlight methane emissions in cattle farms,aiming at a climate change perspective.In this regard,we focused on the research productivity of countries authors,journals and institutions,co-occurrence of keywords,evolution of research trends,and collaborative networking.Based on relevance degree of centrality,methane emissions and greenhouse gases appeared as basic themes,cattle,and dairy cattle appeared as emerging/declining themes,whereas,methane,greenhouse gas and nitrous oxide appeared to fall amongst basic and motor themes.On the other hand,beef cattle,rumen and dairy cow seem to be between motor and niche themes,and risk factors lie in niche themes.The present bibliometric analysis provides research progress on methane emissions in cattle farms.Current findings may provide a framework for understanding research trends and themes in MECF research.
基金financially supported by the National Key Research and Development Program of China(2023YFD2000701)the Natural Science Foundation of Heilongjiang Province,China(YQ2023C011)+1 种基金the Key Research and Development Program of Heilongjiang Province,China(Grant no.2022ZX01A24)the Key Laboratory of Low-carbon Green Agriculture in Northeastern China,Ministry of Agriculture and Rural Affairs of China(LCGANE14)。
文摘As a major contributor to methane production in agriculture,there is a need for a suitable methane inhibitor to reduce ruminant methane emissions and minimize the impact on the climate.This work aimed to explore the influence of cordycepin on rumen fermentation,gas production,microbiome and their metabolites.A total of 0.00,0.08,0.16,0.32,and 0.64 g L^(–1)cordycepin were added into fermentation bottles containing 2 g total mixed ration for in vitro ruminal fermentation,and then the gas produced and fermentation parameters were measured for each bottle.Samples from the 0 and 0.64 g L^(–1)cordycepin addition were selected for 16S rRNA gene sequencing and metabolome analysis.The result of this experiment indicated that the addition of cordycepin could linearly increase the concentration of total volatile fatty acid,ammonia nitrogen,the proportion of propionate,valerate,and isovalerate,and linearly reduce ruminal pH and methane,carbon dioxide,hydrogen and total gas production,as well as the methane proportion,carbon dioxide proportion and proportion of butyrate.In addition,there was a quadratic relationship between hydrogen and cordycepin addition.At the same time,the relative abundance of Succiniclasticum,Prevotella,Rikenellaceae_RC9_gut_group,NK4A214_group,Christensenellaceae_R_(7)_group,unclassified_F082,Veillonellaceae_UCG_001,Dasytricha,Ophryoscolex,Isotricha,unclassified_Eukaryota,Methanobrevibacter,and Piromyces decreased significantly after adding the maximum dose of cordycepin.In contrast,the relative abundance of Succinivibrio,unclassified_Succinivibrionaceae,Prevotellaceae_UCG_001,unclassified_Lachnospiraceae,Lachnospira,Succinivibrionaceae_UCG_002,Pseudobutyrivibrio,Entodinium,Polyplastron,unclassified_Methanomethylophilaceae,Methanosphaera,and Candidatus_Methanomethylophilus increased significantly.Metabolic pathways such as biosynthesis of unsaturated fatty acids and purine metabolism and metabolites such as arachidonic acid,adenine,and 2′-deoxyguanosine were also affected by the addition of cordycepin.Based on this,we conclude that cordycepin is an effective methane emission inhibitor that can change the rumen metabolites and fermentation parameters by influencing the rumen microbiome,thus regulating rumen methane production.This experiment may provide a potential theoretical reference for developing Cordyceps byproduct or additives containing cordycepin as methane inhibitors.
基金supported by the National Natural Science Foundation of China(52074045,52274074)the Science Fund for Distinguished Young Scholars of Chongqing(CSTB2022NSCQ-JQX0028).
文摘Developing deep fragmented soft coalbed methane(CBM)can significantly enhance domestic natural gas supplies,reduce reliance on imported energy,and bolster national energy security.This manuscript provides a comprehensive review of commonly employed coalbed methane extraction technologies.It then delves into several critical issues in the current stage of CBM exploration and development in China,including the compatibility of existing technologies with CBM reservoirs,the characteristics and occurrence states of CBM reservoirs,critical desorption pressure,and gas generation mechanisms.Our research indicates that current CBM exploration and development technologies in China have reached an internationally advanced level,yet the industry is facing unprecedented challenges.Despite progress in low-permeability,high-value coal seams,significant breakthroughs have not been achieved in exploring other types of coal seams.For different coal reservoirs,integrated extraction technologies have been developed,such as surface pre-depressurisation and segmented hydraulic fracturing of coal seam roof strata.Additionally,techniques like large-scale volume fracturing in horizontal wells have been established,significantly enhancing reservoir stimulation effects and coalbed methane recovery rates.However,all of these technologies are fundamentally based on permeation.These technologies lack direct methods aimed at enhancing the diffusion rate of CBM,thereby failing to fully reflect the unique characteristics of CBM.Current CBM exploration and development theories and technologies are not universally applicable to all coal seams.They do not adequately account for the predominantly adsorbed state of CBM,and the complex and variable gas generation mechanisms further constrain CBM development in China.Finally,continuous exploration of new deep CBM exploration technologies is necessary.Integrating more effective reservoir stimulation technologies is essential to enhance technical adaptability concerning CBM reservoir characteristics,gas occurrence states,and gas generation mechanisms,ultimately achieving efficient CBM development.We conclude that while China possesses a substantial foundation of deep fractured CBM resources,industry development is constrained and requires continuous exploration of new CBM exploration and development technologies to utilize these resources effectively.
基金the support from the National Natural Science Foundation of China(52202306)Program from Guangdong Introducing Innovative and Entrepreneurial Teams(2019ZT08L101 and RCTDPT-2020-001)+1 种基金Shenzhen Key Laboratory of Eco-materials and Renewable Energy(ZDSYS20200922160400001)the Provincial Talent Plan of Guangdong(2023TB0012).
文摘Methane(CH4),the predominant component of natural gas and shale gas,is regarded as a promising carbon feedstock for chemical synthesis[1].However,considering the extreme stability of CH4 molecules,it's quite challenging in simultaneously achieving high activity and selectivity for target products under mild conditions,especially when synthesizing high-value C2t chemicals such as ethanol[2].The conversion of methane to ethanol by photocatalysis is promising for achieving transformation under ambient temperature and pressure conditions.Currently,the apparent quantum efficiency(AQE)of solar-driven methane-to-ethanol conversion is generally below 0.5%[3,4].Furthermore,the stability of photocatalysts remains inadequate,offering substantial potential for further improvement.
文摘Recent research progress on the use of Ni-based catalysts supported by various carbon materials,such as carbon nanotubes,graphene,and activated carbon,for the hydrogenation of CO_(2)to CH4 is summarized.The influence of additives and surface modification methods on improving their catalytic performance is discussed as is the reaction mechanism,especially the structurefunction relationship produced by the carbon.The review provides a comprehensive directory for the rational design of carbon-supported Ni-based catalysts for the methanation of CO_(2).
文摘CeO_(2) based semiconductor are widely used in solar-driven photothermal catalytic dry reforming of methane(DRM)reaction,but still suffer from low activity and low light utilization efficiency.This study developed graphite-CeO_(2) interfaces to enhance solar-driven photothermal catalytic DRM.Compared with carbon nanotubes-modified CeO_(2)(CeO_(2)-CNT),graphite-modified CeO_(2)(CeO_(2)-GRA)constructed graphite-CeO_(2) interfaces with distortion in CeO_(2),leading to the formation abundant oxygen vacancies.These graphite-CeO_(2) interfaces with oxygen vacancies enhanced optical absorption and promoted the generation and separation of photogenerated carriers.The high endothermic capacity of graphite elevated the catalyst surface temperature from 592.1−691.3℃,boosting light-to-thermal conversion.The synergy between photogenerated carriers and localized heat enabled Ni/CeO_(2)-GRA to achieve a CO production rate of 9985.6 mmol/(g·h)(vs 7192.4 mmol/(g·h)for Ni/CeO_(2))and a light-to-fuel efficiency of 21.8%(vs 13.8%for Ni/CeO_(2)).This work provides insights for designing graphite-semiconductor interfaces to advance photothermal catalytic efficiency.
基金Supported by the China National Science and Technology Major Project(2025ZD1405700)CNPC Science and Technology Project(2023YQX20117).
文摘Based on the coalbed methane(CBM)/coal-rock gas(CRG)geological,geophysical,and experimental testing data from the Daji block in the Ordos Basin,the coal-forming and hydrocarbon generation&accumulation characteristics across different zones were dissected,and the key factors controlling the differential CBM/CRG enrichment were identified.The No.8 coal seam of the Carboniferous Benxi Formation in the Daji block is 8-10 m thick,typically overlain by limestone.The primary hydrocarbon generation phase occurred during the Early Cretaceous.Based on the differences in tectonic evolution and CRG occurrence,and with the maximum vitrinite reflectance of 2.0%and burial depth of 1800 m as boundaries,the study area is divided into deeply buried and deeply preserved,deeply buried and shallowly preserved,and shallowly buried and shallowly preserved zones.The deeply buried and deeply preserved zone contains gas content of 22-35 m^(3)/t,adsorbed gas saturation of 95%-100%,and formation water with total dissolved solid(TDS)higher than 50000 mg/L.This zone features structural stability and strong sealing capacity,with high gas production rates.The deeply buried and shallowly preserved zone contains gas content of 16-20 m^(3)/t,adsorbed gas saturation of 80%-95%,and formation water with TDS of 5000-50000 mg/L.This zone exhibits localized structural modification and hydrodynamic sealing,with moderate gas production rate.The shallowly buried and shallowly preserved zone contains gas content of 8-16 m^(3)/t,adsorbed gas saturation of 50%-70%,and formation water with TDS lower than 5000 mg/L.This zone experienced intense uplift,resulting in poor sealing and secondary alteration of the primary gas reservoir,with partial adsorbed gas loss,and low gas production rate.A depositional unification and structural divergence model is proposed,that is,although coal seams across the basin experienced broadly similar depositional and tectonic histories,differences in tectonic intensity have led to spatial heterogeneity in the maximum burial depth(i.e.,thermal maturity of coal)and current burial depth and occurrence of CRG(i.e.,gas content and occurrence state).The research results provide valuable guidance for advancing the theoretical understanding of CBM/CRG enrichment and for improving exploration and development practices.
文摘The objective of this study is to propose an optimal plant design for blue hydrogen production aboard a liquefiednatural gas(LNG)carrier.This investigation focuses on integrating two distinct processes—steam methanereforming(SMR)and ship-based carbon capture(SBCC).The first refers to the common practice used to obtainhydrogen from methane(often derived from natural gas),where steam reacts with methane to produce hydrogenand carbon dioxide(CO_(2)).The second refers to capturing the CO_(2) generated during the SMR process on boardships.By capturing and storing the carbon emissions,the process significantly reduces its environmental impact,making the hydrogen production“blue,”as opposed to“grey”(which involves CO_(2) emissions without capture).For the SMR process,the analysis reveals that increasing the reformer temperature enhances both the processperformance and CO_(2) emissions.Conversely,a higher steam-to-carbon(s/c)ratio reduces hydrogen yield,therebydecreasing thermal efficiency.The study also shows that preheating the air and boil-off gas(BOG)before theyenter the combustion chamber boosts overall efficiency and curtails CO_(2) emissions.In the SBCC process,puremonoethanolamine(MEA)is employed to capture the CO_(2) generated by the exhaust gases from the SMR process.The results indicate that with a 90%CO_(2) capture rate,the associated heat consumption amounts to 4.6 MJ perkilogram of CO_(2) captured.This combined approach offers a viable pathway to produce blue hydrogen on LNGcarriers while significantly reducing the carbon footprint.
基金Supported by National Key Research and Development Program of China(No.2023YFA0915000)。
文摘AIM:To investigate the effect of 0.01%low-concentration atropine(LA)on quantitative contrast sensitivity function(qCSF)in children with myopia.METHODS:This paired case-control study included 90 eyes of 58 children who were sex-,age-,and refractionmatched and equally divided into two groups:the 0.01%LA group had undergone 6mo use of daily 0.01%atropine and control group was naïve to LA.Routine ophthalmic examinations and qCSF test without refractive correction were performed.Two groups were compared in monocular and binocular qCSF parameters,including the area under logCSF,CSF acuity,and contrast sensitivity(CS)at 1.0-18.0 cycle per degree(cpd).RESULTS:In the monocular comparison,the CSF acuity of the LA group was significantly higher than that of the control group(7.58±5.51 vs 6.37±4.22 cpd,P<0.05).The subgroup analysis showed that in the 6-9y group,CSF acuity was significantly higher in the LA group than the control group(8.76±6.19 vs 6.54±4.25 cpd,P<0.05),and in the Female group,low refraction sphere group,and high refraction cylinder group,the CS at high spatial frequencies(12.0 and 18.0 cpd)were significantly higher in the LA group than in the control group(all P<0.05).In the binocular test,CSF acuity and CS at 12.0 cpd were significantly higher in the LA group than in the control group(10.95±7.00 vs 8.65±5.12 cpd;0.17±0.33 vs 0.06±0.16,respectively;both P<0.05).CONCLUSION:Use of LA may result in improved CS in children with early onset myopia.
基金This research was supported by"Regional Innovation Strategy"(2023RIS-008)and"C1 Gas Refinery Program"(NRF-2015M3D3D3A1A01064876)through the National Research Foundation of Koreafunded by the Ministry of Education(NRF-2017R1A6A1A03015876).
文摘Methane(CH_(4))has a higher heat capacity(104.9 kcal/mol)than carbon dioxide(CO_(2)),and this has inspired research aimed at reducing methane levels to retard global warming.Hydroxylation under ambient conditions through methanotrophs can provide crucial information for understanding the harsh C-H activation of methane.Soluble methane monooxygenase(sMMO)belongs to the bacterial multi-component monooxygenase superfamily and requires hydroxylase(MMOH),regulatory(MMOB),and reductase(MMOR)components.Recent structural and biophysical studies have demonstrated that these components accelerate and retard methane hydroxylation in MMOH through protein-protein interactions.Complex structures of sMMO,including MMOH-MMOB and MMOH-MMOD,illustrate how these regulatory and inhibitory components orchestrate the di-iron active sites located within the four-helix bundles of MMOH,specifically at the docking surface known as the canyon region.In addition,recent biophysical studies have demonstrated the role of MmoR,aσ54-dependent transcriptional regulator,in regulating sMMO expression.This perspective article introduces remarkable discoveries in recent reports on sMMO components that are crucial for understanding sMMO expression and activities.Our findings provide insight into how sMMO components interact with MMOH to control methane hydroxylation,shedding light on the mechanisms governing sMMO expression and the interactions between activating enzymes and promoters.
文摘CO_(2)-free H_(2)refers to H_(2)production process without CO_(2)emission,which is a promising clean energy in the future.Catalytic decomposition of methane(CDM)is a competitive technology to produce CO_(2)-free H2 with large-scale.However,CDM reaction is highly endothermic and is kinetically and thermodynamically unfavorable,which typically requires a harsh reaction temperature above 800℃.In this work,solar-driven photothermal catalytic decomposition of methane was firstly introduced to produce CO_(2)-free H_(2)relying solely on solar energy as the driving force.A high H_(2)yield of 204.6 mmol g^(–1)h^(–1)was observed over Ni-CeO2 interface under photothermal conditions,along with above 87%reduction in the apparent activation energy(11.2 vs.87.3 kJ mol^(–1))when comparing with the traditional thermal catalysis.Further studies suggested that Ni/CeO_(2)catalyst enhanced optical absorption in visible-infrared region to ensure the heat energy for methane decomposition.The generated electrons and holes participated in the redox process of photo-driven CDM reaction with enhanced separation ability of hot carriers excited by ultraviolet-visible light,which lowered activation energy and improved the photothermal catalytic activity.This work provides a promising photothermal catalytic strategy to produce CO_(2)-free H^(2)under mild conditions.
文摘The conversion of the greenhouse gas methane to value-added chemicals such as alcohols is a promising technology to mitigate environmental issue and the energy crisis.Especially,the sustainable photocatalytic,electrocatalytic and photoelectrocatalytic conversion of methane at ambient conditions is regarded as an alternative technology to replace with thermocatalysis.In this review,we summarize recent advances in photocatalytic,electrocatalytic and photoelectrocatalytic conversion of methane into alcohols.We firstly introduce the general principles of photocatalysis,electrocatalysis and photoelectrocatalysis.Then,we discuss the mechanism for selective activation of C-H bond and following oxygenation over metal,inorganic semiconductor,organic semiconductor,and heterojunction composite systems in the photocatalytic,electrocatalytic and photoelectrocatalytic methane oxidation in detail.Later,we present insights into the construction of effective photocatalyst,electrocatalyst and photoelectrocatalyst for methane conversion into alcohols from the perspective of band structures and active sites.Finally,the challenges and outlook for future designs of photocatalytic,electrocatalytic and photoelectrocatalytic methane oxidation systems are also proposed.
基金supported by the Key Program of National Natural Science Foundation of China(22138008)the financial support provided by the State Key Laboratory of Catalytic Materials and Reaction Engineering(RIPP,SINOPEC)+1 种基金the Program of National Natural Science Foundation of China(22478257)Sichuan Province Advanced Building Materials Production-Education Integration Innovation Demonstration Platform(Chuancaijiao[2022]No.106).
文摘Introducing methane at the anode side of a solid oxide electrolysis cell(SOEC)has been proven to effectively suppress the oxygen evolution reaction(OER),thereby enabling hydrogen production at significantly lower voltages.In this work,a double perovskite oxide,Sr_(2)Fe_(1.4)Pt_(0.1)Mo_(0.5)O_(6-δ)(abbreviated as Pt-SFM),was successfully synthesized by a liquid-phase method and employed as both an electronic conductor and a catalyst for methane oxidation at the SOEC anode.Following high-temperature treatment under a reducing atmosphere,platinum(Pt)nanoparticles were exsolved from the perovskite lattice and uniformly dispersed on the oxide surface.These exsolved Pt nanoparticles act as highly active sites for methane adsorption and oxidation.Electrochemical performance tests were conducted at 1123.15 K,and the results demonstrated that the Pt-SFM cell treated for 20 h(Pt-SFM 20 h)achieved a current density of 0.85 A·cm^(-2)at an applied voltage of 1.40 V.This performance corresponds to a 102.4%enhancement compared to the undoped SFM 20 h cell.The superior performance is attributed to the presence of exsolved Pt,which significantly improves the catalyst's ability to adsorb and dissociate methane molecules.Electrochemical impedance spectroscopy(EIS)analysis under open-circuit conditions revealed that the polarization impedance of the Pt-SFM 20 h cell was 1.25Ω·cm^(2),which is 49.2%lower than that of the SFM 20 h cell.Furthermore,a 45-h long-term stability test showed that the Pt-SFM 20 h cell maintained a stable performance,with a low voltage degradation rate of only 0.67 mV·h^(-1).
基金The National Natural Science Foundation of China under contract Nos 42130410 and 42576285the Science and Technology Innovation Project of Laoshan Laboratory under contract No.LSKJ202203503the China Geological Survey Project under contract No.DD20230064.
文摘The ocean represents a vast carbon reservoir,where methane concentrations reflect a balance between production and consumption processes.In this study,marine sediments harboring abundant aerobic methanotrophs were incubated under varying methane concentrations.We investigated changes in methane oxidation rates and the community structure of these methanotrophs during incubation.Results demonstrate that methane concentration regulates aerobic methane oxidation.The oxidation rate increased with rising methane concentration up to 50%.However,beyond this threshold,at 80%methane,the oxidation rate declined.Following incubation,the abundance of aerobic methanotrophs increased significantly,with Methylobacterium becoming the dominant genus.Relative abundances of other bacteria potentially associated with alkane degradation,including Planomicrobium,Bacillus,Methylophaga,Erythrobacter,Gillisia and Pontibacter,were also significantly enriched.These findings provide a scientific basis for predicting marine methane emission dynamics,which is crucial for assessing and mitigating the greenhouse gas impact of methane.
