化学反应工程Chapter 8

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1、化学反应工程Chapter8PotpourriofMultipleReactionsChapter7consideredreactionsinparallel.Thesearereactionswheretheproductdoesnotreactfurther.Thischapterconsidersallsortsofreactionswheretheproductformedmayreactfurther.Herearesomeexamples:SeriesARSReversibleandirreversibleSeriesparallel,orconsec

2、utive-competitiveTUDenbighsystem化学反应工程ARSReversibleARSReversiblenetworkWedeveloporpresenttheperformanceequationsofsomeofthesimplersystemsandpointouttheirspecialfeaturessuchasmaximaofintermediates.化学反应工程proceedonlyinthepresenceoflight,thattheystoptheinstantthelightisturnedoff,andthatfo

3、ragivenintensityofradiation,therateequationsare(2)(3)(4)8.1IRREVERSIBLEFIRST-ORDERREACTIONSINSERIESForeasyvisuali’zationconsiderthatthereactions(1)化学反应工程QualitativeDiscussionAboutProductDistribution.ConsiderthefollowingtwowaysoftreatingabeakercontainingA:First,thecontentsareuniformlyi

4、rradiated;Second,asmallstreamiscontinuouslywithdrawnfromthebeaker,ir’radiated(照射),andreturnedtothebeaker;therateofabsorptionof‘radiantenergyisthesameinthetwocases.Thetwoschemes(计划,方案)areshowninFigs.8.1and8.2.化学反应工程Figure8.1Concentration-timecurvesifthecontentsofthebeakerareirradiatedu

5、niformly.化学反应工程Figure8.2Concentration-timecurvesforthecontentsofthebeakerifonlyasmallportionofthefluidisirradiatedatanyinstant.化学反应工程Inthefirstbeaker(showninFig.8.1),whenthecontentsarebeingirradiatedallatthesametime,thefirstbitoflightwillattackAalonebecauseonlyAispresentatthestart.The

6、resultisthatRisformed.WiththenextbitoflightbothAandRwillcom’pete;however,Aisinverylargeexcesssoitwillprefe’rentially(优先地)absorbthe‘radiantenergytodecomposeandformmoreR.DuringthisprocessAdisappearsandproductsareformed.IstheproductdistributionofRandSdifferentinthetwobeakers?Letusseewhet

7、herwecananswerthisquestionqualitatively(定性地)forallvaluesoftherateconstants.化学反应工程Thus,theconcentrationofRwillrisewhiletheconcentrationofAwillfall.ThisprocesswillcontinueuntilRispresentinhighenoughconcentrationsothatitcancompetefavorablywithAforthe‘radiantenergy.Whenthishappens,amaximu

8、mRcon