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1、http://cec-lab.stanford.edu/research01.phpDFTandCatalysisDensityfunctionaltheoryisusedtocarryoutelectronicstructurecalculationsthatassistinprovidingunderstandingofmechanismsresponsibleforgas-surfacereactivity.TheUShasover300GWofpowercapacityfrompulverizedcoalcombustion.R
2、educingemissionsfromcoalwillrequirepostcombustioncapturetechnologytoretrofittheseexistingpowerplants.EffortsintheCleanEnergyConversionslabaremadetocapturetracemetals(TMs)andCO2fromcoalconversionprocesses.Topic1:TraceMetalCaptureThereisincreasingconcernregardingtheemissio
3、noftracemetals,suchasmercury(Hg),arsenic(As)andselenium(Se)fromanthropogenicsources.TheseTMsoccurasimpuritiesinminerals,particularlymetalsulfides,aswellasorganicmatterincoal.Followingcoalcombustion,theyarereleasedbackintotheenvironmentthroughfluegasemissionsandflyashdisp
4、osal.EnvironmentalregulationsforbothHgandSeareimminentunderthecurrentadministrationand19statesalreadyhavemercurycontrolsinplace.ThetwoprimaryroutestoimproveTMemissionscontrolaretoeither(1)oxidizethemduringcombustiontopromotetheparticle-boundformorwater-solubleform,or(2)t
5、oemploysorbentstodirectlycapturethem.Surface-assisted(flyash,ductwork,selectivecatalyticreductioncatalyst(SCR),electrostaticprecipitator(ESP),baghouse,etc.)captureandoxidationoffluegasTMsisthoughttoalreadyoccurincombustionexhaust,buttoanunknownextent.Thecomplexandhighlyv
6、ariableflyashcompositionandstructure,furthercomplicatedbythetemperaturerangesandconditionsofcoalcombustion,currentlyplacesthispathtofluegastreatmentina"blackbox."ThephysiochemicalandmineralogicalcharacteristicsofnaturaladsorbingsurfacesandthefundamentalmechanismsofTMadso
7、rptionunderenvironmentalconditionsneedtobeexaminedtounderstandTMspeciationinfluegasesandonthesurfacesoffluegassolidstopotentiallyguideanunderstandingofpotentialremediationstrategies.Thecurrentlackofin-depthunderstandingofhowTMspeciesinteractwithflyashsurfacesstandsinthew
8、ayofoptimizingoxidationreactionsforbetteremissioncontrol.Determiningtheheterogeneousoxidationpathwaysan
