简介:摘要在固定床反应器上研究了经铈促进的(Ce-promoted)和未经铈促进的5Co-15Ni/Al2O3,催化剂在CH4干法转化反应中的性能。虽然添加铈(2.5wt%)能够明显减少积碳,降幅可达50%,但CH4的反应速度并没有出现明显的提高(增幅小于5%),活化能也没有出现明显的改变。经铈促进的催化剂抗碳(carbonresistance)能力提高,这要归因于反应过程中铈离子稳定的多次氧化态(multipleoxidationstates)。所采用的催化剂的TPR-TPO揭示了两种类型的碳成分(carbonspecies)。第一种是活性Cα,它易于被H2气化,而且还参与氧化铈的氧化还原反应;第二种是相对的非活性Cβ,它只能被O2移除,而且不参与氧化还原反应循环。文中还提出了这种反应的双中心(dual-site)兰格缪尔(Langmuir)-Hinshelwood机理。
简介:摘要:CO2气体溶于水中形成碳酸后引起电化学腐蚀,如不及时采取有效措施,将导致油套管的严重破坏甚至油井报废。CO2对油、套管的腐蚀是油田开发的一个亟待解决的重要课题。
简介:LakesinTibetPlateauwithlittleeffectsofhumanactivitiesserveasimportantindicatorsofclimatechange.ThisstudyanalysedremotesensingdataandlongtermclimatevariablestoexaminethehydrologicalresponseoflakesinNamCoBasin.TheareachangesoflakeswereextractedbyLandsatTM/ETM+andanalysedbySRTM3DEM.AndtheICESatelevationdatabetween2003and2009wereusedtoobservethelakeleveloftheNamCoLake.Theresultsshowthatthenumberofnewformedglacierlakesincreasedby36%andtheareaofglacierlakesincreasedby36.7%(0.97km~2)from1991to2011.Atthesametime,thesurfaceareaoftheNamCoLakeexpandedby3.71%(72.64km~2)oftheoriginalsizein1991,withatendencyvalueof3.63km~2peryear.ThelakeleveloftheNamCoLakeshowsanincreasetendencyof0.24mperyearduring2003–2009.Thesevariationsappeartoberelatedtoanincreaseinmeanannualtemperatureof0.06oCperyear,andanincreaseinannualprecipitationof2.1mmperyearinsummerinthelasttwodecades.Theincreasednumberoflakesandincreasedareaofglaciallakesreachedapeakatanaltitudeof5500–5600ma.s.l..Thenumberofnewformedglacierlakesandtheareaofglacierlakestendtohigheraltitudes.ClimatechangehasanimportantimpactonthevariationoftheglacierlakesandtheNamCoLake.
简介:Multi-beamSonarandSide-scanSonarcompensateeachother.Inordertofullyutilizeallinformation,itisnecessarytofusetwokindsofimageanddata.Andtheimageco-registrationisanimportantandcomplicatedjobbeforefusion.Thispapersuggestscombiningbathymetricdatawithintensityimage,obtainingthecharacteristicpointsthroughtheminimalanglesoflines,andthendecidingthecorrespondingimagepointsbythemaximalcorrelatecoefficientinsearchingspace.Finally,thesecondorderpolynomialisappliedtothedeformationmodel.Aftertheimageshavebeenco-registered,Waveletisusedtofusetheimages.Itisshownthatthisalgorithmcanbeusedintheflatseafloorortheisotropicseabed.Verificationismadeinthepaperwiththeobserveddata.
简介:CarboncycleisconnectedwiththemostimportantenvironmentalissueofGlobalChange.Asoneofthemajorcarbonreservoirs,oceansplayanimportantpartinthecarboncycle.Inrecentyears,ironseemstogiveusagoodnewsthatoceanicironfertilizationcouldstimulatebiologicalproduc-tivityasCO2sinkofhuman-producedCO2.Oceanicironfertilizationexperimentshaveverifiedthataddingironintohighnutrientlowchlorophyll(HNLC)seawaterscanincreasephytoplanktonproductionandexportorganiccarbon,andhenceincreasecarbonsinkofanthropogenicCO2,toreduceglobalwarming.Insixtydays,theexportorganiccarboncouldreach10000timesforaddingironbymodelpredictionandinsituexperiment,I.e.TheatmosphericCO2uptakeandinorganiccarbondrawdowninupperseawatersalsohavethesamemagnitude.Therefore,oceanicironfertilizationisoneofthestrate-giesforincreasingcarbonsinkofanthropogenicCO2.Thepaperisfocusedontheironfertilization,es-peciallyinsituoceanironexperimentsinorderthatthefutureresearchismoreefficient.
简介:Shallowfreshwaterbodiesinpeatareascouldbeanimportantcontributortogreenhousegasesintheatmosphere.Inthisstudy,thepartialpressureofCO2inthesurfacewateroftheDianshanLakewasinvestigatedinsituinAugust2011.TheaveragepCO2inthestudyareawas2300μatmandfluctuatedwithintherangeof989–5000μatm.pCO2showedareversetrendtothevariationsofpHandDOinthesurfacewateroftheDianshanLake.ThewatertoairdiffusionfluxofCO2oftheupstream,middlelakeanddownstreamwererespectively63,33and14mmol/m2/d.Onaverage,thediffusionfluxofCO2ofthewholelakewas31mmol/m2/d.Consequently,ourresultsshowthatduringthesamplingseason,theDianshanLakeappearstobeagreatsourceofCO2.ItisalsodemonstratedthatrespirationcouldbethedominantbiochemicalreactionintheDianshanLakeinsummer.
简介:Thecurrentadvancesinthestudyofgeochemistryandpaleo-oceanographyoftheCo-richcrustarereviewedinthispaper.WesummarizethestudyofgeochemistryoftheCo-richcrust,discussthediffusionofelementsintheCo-richcrustandtheexchangewithambientseawater.Besides,wediscusstheeffectofphosphatizationandsubstraterocksonthecompositionoftheCo-richcrust.Wealsointroducetheapplicationofstableisotopes(includingthestableisotopesofPb,Nd,andHf),radioactiveisotopes(includingtheradioactiveisotopesofBe,UandTh),andelements(includingthemajorelements,minorelementsandrareearthelements)tothestudyofpaleo-oceanographyoftheCo-richcrust.
简介:Inthisstudy,wepresentanewmethodtocomputeinternalco-seismicdeformationsofahomogeneoussphere,basedonourpreviousapproach(Dongetal.2016).Inpracticalnumericalcomputations,weconsiderastrike-slippointsourceasanexample,andcomputetheverticalco-seismicdisplacementondifferentinternalsphericalsurfaces(includingtheEarthsurface).Numericalresultsshowthattheinternalco-seismicdeformationsaregenerallylargerthanthatontheEarthsurface;especially,themaximumco-seismicdisplacementappearsaroundtheseismicsource.Theco-seismicdisplacementsareoppositeinsignfortheareasoverandbeneaththepositionoftheseismicsource.Theresultsalsoindicatethatthecurvatureeffectoftheinternaldeformationisprettylarge,andlargerthanthatontheEarthsurface.Theresultsindicatethatthedislocationtheoryforasphereisnecessaryincomputinginternalco-seismicdeformations.
简介:Inthisstudy,weanalyzetheco-seismicresponseofwaterlevelsintheJiajiwelltostrongearthquakes(MS≥7.8)from2001to2010atanepicentraldistancelessthan8000km.Weinvestigatedtheco-seismicvariationformofwaterlevels,andanalyzedtherelationshipbetweentheamplitudeofwaterlevelvariationandthemagnitudeandtheepicentraldistance.Wethencheckedtheseismicwavephaseswhenthechangesofwaterleveloccurred.Itwasshownthat:(1)thewaterlevel'sco-seismicresponseismainlycharacterizedbyescalationwithnooscillation;(2)theamplitudeofwaterlevelchangehasacertainconnectionwithepicentraldistanceandmagnitude;(3)co-seismicresponseofwaterlevelsintheJiajiwellshowsacertaindirectivity;(4)mostoftheco-seismicresponseswerecausedbysurfacewaves,andsomebylong-periodSwaves.