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158 个结果
  • 简介:MacroscopicSiO_2sphereswithahomogeneousaminedistributionweresynthesizedbyaone-stepemulsionbasedsynthesisapproachinaflowcolumnreactor.TheCO_2adsorptioncapacityofthenanostructuredamine-functionalizedsilicasphereswasstudiedinabsenceandpresenceofH_2O.Thestructuralpropertieswereadjustedbyvaryingsolventsandsurfactantsduringthesynthesisand,atconstantamineloadings,werefoundtobethemainfactorforinfluencingtheCO_2sorptioncapacities.Underwater-freeconditionsCO_2isboundtotheaminogroupsviatheformationofcarbamates,whichrequiretwoneighboringaminogroupstoadsorboneCO_2molecule.Atconstantamineconcentrationssorbentswithlowersurfaceareaallowtoestablishahigheraminedensityonthesurface,whichenhancestheCO_2uptakecapacitiesunderdryconditions.InpresenceofH_2OtheCO_2adsorptionchangesto1:1stoichiometryduetostabilizationofcarbamatesbyprotonationofH_2Oandformationoffurtherspeciessuchasbicarbonates,whichshouldinprincipledoubletheadsorptioncapacities.LowconcentrationsofphysisorbedH2O(0.3mmol/g)didnotimpairtheadsorptioncapacityoftheadsorbentsforCO_2,whileathigherwateruptakes(0.6and1.1mmol/g)theCO_2uptakeisreduced,whichcouldbeattributedtocapillarycondensationofH_2Oorformationofbulkyreactionproductsblockinginnerporesandaccesstoactivesites.

  • 标签: 表面活性剂 纳米结构 溶剂 硅球 自组装 功能化
  • 简介:ByFP-LAPWcalculations,thestructural,elastic,DebyeandCurietemperatures,electronicandmagneticpropertiesofCo2VAlareinvestigated.TheresultsindicatethatFerromagnetic(FM)phaseismorestablethanAntiFerromagnetic(AFM)andNon-magnetic(NM)ones.Inaddition,C11–C12>0,C44>0,andB>0soCo2VAlisanelasticallystablematerialwithhighDebyetemperature.Also,theB/Gratioexhibitsaductilitybehavior.TherelativelyhighCurietemperatureprovidesitasafavorablematerialforspintronicapplication.It’selectronicandmagneticpropertiesarestudiedbyGGA+Uapproachleadingtoa100%spinpolarizationatFermilevel.

  • 标签: 第一性原理计算 高居里温度 半金属 化合物 原子力显微镜 弹性材料
  • 简介:Theglass-formingability(GFA)andmagneticpropertiesoftheGd_(50)Coso-basedamorphousaiioywithAladditionsubstitutionforCoareinvestigated.ItisfoundthattheGFAandmagneto-caloriceffectoftheGd_(50)Co_(45)Al_5amorphousaiioyarebetterthanGd_(50)Co_(50)amorphousalloy.Themaximummagneticentropychange(-△S_m~(peak))andthemagneticrefrigerantcapacityoftheamorphousalloyunderafieldof5Tareabout6.64J·kg~(-1)K~(-1)and764J·kg~(-1),respectively.Thefielddependenceofmagneticentropychangemeetstheonepredictedbythemeanfieldtheory,whichisinvestigatedforabetterunderstandingofthemagneto-caloricbehaviorsoftheGd_(50)Co_(45)Al_5amorphousalloy.

  • 标签: 玻璃形成能力 共晶合金 钴基非晶合金 磁性能 磁热效应 制冷能力
  • 简介:ThreeseriesofCeO2/CuOsampleswerepreparedbyimpregnationmethodandcharacterizedbyXRD,N2adsorption-desorption,temperatureprogrammedreduction(TPR),XPSandTEMtechniques.IncomparisonwiththesamplespreparedwithCuOasinitialsupport,thesampleswithCu(OH)2asinitialsupporthavehigherreducibilitiesandsmallerrelativeTPRpeakareas,andalsolargerspecificsurfaceareasatcalcinationtemperaturesof400℃–600℃.Asaresult,Cu(OH)2isbetterthanCuOasinitialsupportforpreferentialoxidationofCOinexcessH2(CO-PROX).Thebestcatalyticperformancewasachievedonthesamplecalcinedat600℃andwithanatomicratioofCe/Cuat40%.XPSanalysesindicatethatmoreinterfacelinkagesCe-O-Cucouldbeformedwhenitwascalcinedat600℃.AndtheatomicratioofCe/Cuat40%ledtoaproperreducibilityforthesampleasillustratedbytheTPRmeasurements.

  • 标签: 氧化铜催化剂 选择性氧化 氧化铈 支护效果 二氧化碳 程序升温还原
  • 简介:目的:探究季铵型聚合物CO2解吸附过程温度和CO2浓度等变量对解吸附热力学和动力学的影响;研究空气CO2捕集供给植物增产的耦合方法,降低空气CO2捕集与利用的能耗与成本。创新点:1.基于变湿吸附技术,探究了季铵型聚合物CO2解吸附过程的热力学及动力学特性;2.获得了CO2作为气肥供给植物增产的关键影响参数;3.建立并优化了空气CO2捕集与植物利用的耦合模型。方法:1.通过CO2吸附平衡与动力学实验,获得季铵型聚合物CO2解吸附的平衡常数和动力学常数的影响参数;2.通过植物CO2吸收实验,获得CO2供给植物增产过程中CO2浓度和光照强度对吸收速率的影响;3.通过理论推导,构建解吸附CO2浓度与吸附剂质量、温度以及吹扫气流量等的关系,获得空气CO2捕集与植物增产的耦合模型并计算CO2捕集的能耗与成本。结论:1.季铵型聚合物材料吸附CO2的平衡常数随温度的升高而降低;吸附、解吸附动力学常数随温度的升高而升高。2.CO2供给植物增产的最佳浓度和光照强度为1000ppm和8000lux。3.基于优化的空气捕集与植物利用的耦合算法,CO2的捕集能耗与成本分别为35.67kJ/mol和34.68USD/t。

  • 标签: 直接空气捕集 解吸附动力学 温室 CO2气肥 成本分析
  • 简介:ThreephasePebax?MH1657/PEG-ran-PPG/CuBTC(polymer/liquid/solid)wassuccessfullydepositedasaselectivelayeronaporousPolysulfone(PSF)support.Infact,thebeneficialpropertiesofPEG(highselectivity)withthoseofPPG(highpermeability,amorphous)havebeencombinedwithsuperiorpropertiesofmixedmatrixmembrane(MMMs).ThemembraneswerecharacterizedbyDSC,TGAandSEM,whileCuBTCwascharacterizedbyCO2andCH4adsorptiontest.Statisticallybasedexperimentaldesign(centralcompositedesign,CCD)wasappliedtoanalyzeandoptimizetheeffectofPEG-ran-PPG(10–50wt%)andCuBTC(0–20wt%)masscontentsontheCO2permeanceandCO2/CH4idealselectivity.Basedontheregressioncoefficientsoftheobtainedmodels,theCO2permeancewasnotablyinfluencedbyPEG-ran-PPG,whileCuBTChasthemostsignificanteffectontheCO2/CH4idealselectivity.Undertheoptimumconditions(PEG-ran-PPG:32.76wt%andCuBTC:20wt%),nearly620%increaseintheCO2permeanceand43%enhancementintheCO2/CH4idealselectivitywasobservedcomparedtotheneatPebax.Theeffectofpressure(3,9and15bar)onthepureandmixedgasseparationperformanceofthecompositemembraneswasalsoinvestigated.ThehighsolubilityofCO2inthemembranesresultedintheenhancementofCO2permeabilitywithincreaseingaspressure.

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  • 简介:Removalofcarbonylsulfide(COS)fromCO2streamissignificantfortheproductionandutilizationoffoodgradeCO2.ThisstudyinvestigatestheadsorptionperformanceofAg/NaZSM-5asadsorbentpreparedbyincipientwetnessimpregnationfortheremovalofCOSfromaCO2streaminafixed-bedadsorptionapparatus.Effectsofvariousconditionsonthepreparationofadsorbent,adsorptionanddesorptionwereintensivelyexamined.TheresultsrevealedthatCOScanberemovedtobelow1×10-9fromaCO2stream(1000ppmCOS/CO2)usingAg/NaZSM-5(10wt%AgNO3)withanadsorptioncapacityof12.86mg·g-1.Theadsorbentcanbefullyregeneratedusinghotairat450C.Theadsorptionabilityremainedstableevenaftereightcyclesofregeneration.

  • 标签: CARBONYL SULFIDE adsorption π-complexation COMPLETELY regeneration
  • 简介:CrystallineTiO2(P25)andisolatedtitanatespeciesinaZSM-5structure(TS-1)weremodifiedwithAuandAg,respectively,andtestedinthegas-phasephotocatalyticCO2reductionunderhighpurityconditions.Thenoblemetalmodificationwasperformedbyphotodeposition.LightabsorbancepropertiesofthecatalystsareexaminedwithUV–Visspectroscopybeforeandaftertheactivitytest.Inthegas-phasephotocatalyticCO2reduction,itwasobservedthatthecatalystswithAgnanostructuresaremoreactivethanthosewithAunanostructures.Itisthusfoundthattheenergeticdifferencebetweenthebandgapenergyofthesemiconductorandthepositionoftheplasmonisinfluencingthephotocatalyticactivity.Potentially,plasmonexcitationduetovisiblelightabsorptionresultsinplasmonresonanceenergy,whichaffectstheexcitationofthesemiconductorpositively.Therefore,anoverlapbetweenbandgapenergyofthesemiconductorandmetalplasmonisneeded.

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  • 简介:Carbondioxide(CO2)captureusingmagnesiumoxide(MgO)-basedadsorbentsatintermediatetemperatureshasbeenregardedasaveryprospectivetechnologyfortheirrelativelyhighadsorptioncapacity,lowcost,andwideavailability.Duringthepastfewyears,greatefforthasbeendevotedtothefabricationofmoltensalts-modifiedMgO-basedadsorbents.TheextraordinaryprogressachievedbycoatingwithmoltensaltsgreatlypromotestheCO2capturecapacityofMgO-basedadsorbents.Therefore,wefeelitnecessarytodeliveratimelyreviewonthistypeofCO2capturingmaterials,whichwillbenefittheresearchersworkinginbothacademicandindustrialareas.Inthiswork,weclassifiedthemoltensaltsmodifiedMgOadsorbentsintofourcategories:(1)homogenousmoltensalt-modifiedMgOadsorbents,(2)moltensalt-modifieddoublesalts-basedMgOadsorbents,(3)mixedmoltensalts-modifiedMgOadsorbents,and(4)moltensalts-modifiedMgO-basedmixedoxidesadsorbents.Thiscontributioncriticallyreviewstherecentdevelopmentsinthesyntheticmethod,adsorptioncapacity,reactionkinetics,promotionmechanism,operationalconditionsandregenerabilityofthemoltensalts-modifiedMgOCO2adsorbents.Thechallengesandprospectsinthispromisingfieldofmoltensalts-modifiedMgOCO2adsorbentsinrealapplicationsarealsobrieflymentioned.

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  • 简介:Mg2Ni合金以价格低廉、高能量密度,而引起人们的广泛关注。本文对Mg2Ni贮氢合金的结构、性能特别是电化学性能,以及常用的改性方法进行综述。

  • 标签: 贮氢合金 MG2NI 电化学性能 掺杂 复合
  • 简介:文章慨述了微步进电机的原理设计、结构设计、加工方法以及该电机的扫描电镀照片等。该电机的转于和定于由LIGA技术制造完成.线圈由手工在显微镑下绕制完成,转子直径2mm.整个电机直径5mm。

  • 标签: LIGA 超微步进电机 微机械系统 微加工技术 研制 光刻
  • 简介:本文用少体方法对A≤4的S壳核动力学结构进行系统研究,同时研究A≤3的普通原子核的结构,通过比较,看到了子进入核内使结构产生变化,子的加入,造成壳心核的缩聚,核子间均方根距离缩短,子在核内起胶粘凝聚作用。对这些核体系内部结构的研究表明.粒子间相对运动主要处于Os轨道。

  • 标签: 均方根距离 相对运动 动力学结构 Λ超核 基态能量 互作用