查看更多>>摘要：In the long term,coal will remain a competitive resource in the thermal power sector,primarily due to its abundant global reserves and low costs.Despite numerous factors,including significant environmental concerns,the global share of coal power generation has remained at 40％over the past four decades.Efficient and clean coal combustion is a high priority wherever coal is used as a fuel.An improved low-power boiler design has been proposed to enhance efficiency during fixed-bed coal combustion.This design reduces harmful emissions into the atmosphere by optimizing parameters and operating modes.In this study,mathematical modeling of gas velocity and temperature distribution during fixed-bed coal combustion was conducted for a conventional grate system and an improved grate-free system.Experimental methods were employed to develop descriptive airflow models in the fixed coal layer,considering nozzle diameter and air supply pressure in the furnace chamber without a grate system.Comparative evaluations of fixed-bed coal combustion rates were performed using an experimental laboratory setup with both grate and grate-free stove systems.
查看更多>>摘要：Cu-based materials are commonly used in electrocatalytic nitrate reduction reactions(NO3RR).NO3RR is a"two birds,one stone"approach,simultaneously removing NO3-pollutants and producing valuable ammonia(NH3).However,the strong coordination between the NO3-intermediate and the catalytic active sites seriously hinders the conversion efficiency.Here,we determined that,through encapsulation strategies,the carbon layer could weaken the NO3-intermediate binding to active sites,resulting in higher NH3 yields.We experimentally fabricated electrocatalysts,i.e.,Cu nanoparticles encapsulating(or loaded on)N-doped carbon nanofibers(NCNFs)called Cu@NCNFs(Cu-NCNFs),using electrostatic spinning.As a result,Cu@NCNFs can achieve NH3 yields of 17.08 mg/(h·mgcat)at a voltage of-0.84 V and a Faraday efficiency of 98.15％.Meanwhile,the electrochemical properties of the Cu nanoparticles on the surface of carbon fibers(Cu-NCNFs)are lower than those of the Cu@NCNFs.The in situ Raman spectra of Cu@NCNFs and Cu-NCNFs under various reduction potentials during the NO3RR process show that catalyst encapsulation within carbon layers can effectively reduce the adsorption of N species by the catalyst,thus improving the catalytic performance in the nitrate-to-ammonia catalytic conversion process.
查看更多>>摘要：Combusting refuse for energy production is promising for their treatment and disposal.However,because of geographical constraints,there has not been a stable model for the energy utilization of refuse in low-oxygen plateau areas.This paper took Lhasa as an example to conduct gasification and incineration experiments on local representative combustible refuse,and relevant energy conversion laws were investigated.Results showed that under gasification and incineration modes,the energy conversion rate of any component of refuse can reach 75％and 85％in low-oxygen plateau areas at temperatures of 450 and 650 ℃,respectively,which were 5％-10％lower than those in plain areas.The regional distribution of energy con-version of refuse in Lhasa showed that the energy conversion rate under the gasification mode was 3％-5％lower than that of the incineration mode at 450 and 650 ℃.In terms of temperature,the energy conversion rates of refuse were 5％-10％lower at 450 ℃ than those at 650 ℃,but an energy conversion rate of more than 85％can still be achieved.Thus,gasifica-tion,incineration,or gasification-assisted secondary incineration at temperatures of at least 450 ℃ is suitable for energy recovery of refuse in low-oxygen plateau areas.
Maria TimofeevaDmitry S.DmitrievDanil D.MaltsevArtem A.Lobinsky...
508-517页
查看更多>>摘要：Porous metal-organic frameworks(MOFs)have been recently discovered to be efficient catalysts for energy applications and green technologies.Here,we report on a scalable catalytic platform using Cu-based MOFs for electrocatalytic alkaline hydrogen evolution reaction.First,the solvothermal synthesis of Cu-BTC MOFs(BTC=1,3,5-benzenetricarboxylate)at 85 ℃ and a 1∶60 ligand-to-solvent ratio allowed for minimizing the chemical consumption.Second,the obtained platform demonstrated enhanced electrochemical performance compared with commercially available Cu-based MOFs,with a poten-tial of-230 versus-232 eV,logarithm of the current density of-3.6 versus-4.2 cm2,and electrochemical surface area of 75 versus 25 cm2 per cm2 of geometric area,respectively.Morphological and Raman analyses also revealed that the high concentration of defects in the obtained submicron Cu-BTC MOFs can contribute to their improved catalytic performance.Thus,our findings pave the way to the low-cost synthesis of energy-efficient MOF-based catalysts for hydrogen production.
查看更多>>摘要：Supercapacitors have emerged as a promising class of energy storage technologies,renowned for their impressive specific capacities and reliable cycling performance.These attributes are increasingly significant amid the growing environmental challenges stemming from rapid global economic growth and increased fossil fuel consumption.The electrochemical per-formance of supercapacitors largely depends on the properties of the electrode materials used.Among these,iron-based sulfide(IBS)materials have attracted significant attention for use as anode materials owing to their high specific capacity,eco-friendliness,and cost-effectiveness.Despite these advantages,IBS electrode materials often face challenges such as poor electrical conductivity,compromised chemical stability,and large volume changes during charge-discharge cycles.This review article comprehensively examines recent research efforts aiming at improving the performance of IBS materials,focusing on three main approaches:nanostructure design(including OD nanoparticles,1D nanowires,2D nanosheets,and 3D structures),composite development(including carbonaceous materials,metal compounds,and polymers),and material defect engineering(through doping and vacancy introduction).The article sheds light on novel concepts and methodologies designed to address the inherent limitations of IBS electrode materials in supercapacitors.These conceptual frameworks and strategic interventions are expected to be applied to other nanomaterials,driving advancements in electrochemical energy conversion.
查看更多>>摘要：Cu-based catalysts have been extensively used in methanol steam reforming(MSR)reactions because of their low cost and high efficiency.ZnO is often used in commercial Cu-based catalysts as both a structural and an electronic promoter to stabilize metal Cu nanoparticles and modify metal-support interfaces.Still,the further addition of chemical promoters is essential to further enhance the MSR reaction performance of the Cu/ZnO catalyst.In this work,CeO2-doped Cu/ZnO catalysts were prepared using the coprecipitation method,and the effects of CeO2 on Cu-based catalysts were systematically investigated.Doping with appropriate CeO2 amounts could stabilize small Cu nanoparticles through a strong interaction between CeO2 and Cu,leading to the formation of more Cu+-ZnOx interfacial sites.However,higher CeO2 contents resulted in the forma-tion of larger Cu nanoparticles and an excess of Cu+-CeOv interfacial sites.Consequently,the Cu/5CeO2/ZnO catalyst with maximal Cu-ZnO interfaces exhibited the highest H2 production rate of 94.6 mmolHi/(gcat·h),which was 1.5 and 10.2 times higher than those of Cu/ZnO and Cu/CeO2,respectively.
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