硅烷化改性对HZSM--5分子筛上间二甲苯异构化反应的影响

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1、北京化工大学硕士学位论文选择性降低，二甲苯损失严重，不利于间二甲苯的异构化反应。采用单因素实验法考察了胶溶剂硝酸用量、扩孔剂种类及其用量对改性分子筛的催化性能和强度的影响，结果表明，(1)随着硝酸胶溶剂用量的增加，催化剂的活性降低，对二甲苯选择性增加，成型催化剂的强度随着硝酸用量的增加先增加后减少，适宜的硝酸用量在5％．10％之间；(2)以PEG20000为扩孔剂时，改性催化剂的活性和对位选择性都得到不同程度的提高，所制备的成型催化剂强度适中，因此扩孔剂PEG20000是较合适的扩孔剂；(3)改性催化剂活

2、性随着PEG20000用量的增加呈现先增加后减少的趋势，强度则一直减少，适宜的PEG20000用量在5％．10％之间。关键词：正硅酸乙酯，化学液相沉积法，间二甲苯异构化，酸碱处理，成型M-XYLENEISoMERIZ-江IONoVERSILICON-MODIFIEDHZSM．5ZEOLITECATALYSTABSTRACTHZSM．5zeolkewasmodifiedbychemicalliquiddeposition(CLD)Witlltetraethylorthosilicate(TEOS)．Aser

3、iesofzeolitesmodifiedbydifferentcontentofTEOSwerepreparedform-xyleneisomerization．Thereactionperformancesofthesezeoliteswereevaluatedusinganisothermalfixedbedintegralreactor．ThesuitabledepositionconditionsformodifiedHZSM-5wereinvestigatedincludingtheCLDso

4、lventtype,theamountofCLDagent，CLDtime，CLDcyclenumbers．TheresultsshowedthatwiththeincreaseofSi02deposition，theconversionofm—xyleneandxylenelossdecreased，para·xyleneselectivityandPX／OXradioincreased．TheappropriateamountofTEOSwasbetweenO．049／gand0．05∥gforthe

5、singledeposition．TheappropriateCLDtimewasmorethan6h．TheappropriateCLDsolventtypewascyclohexane．Multi．．cycledepositioncouldimprovetheeffectivenessofSi02deposition．ThepropertiesofHZSM一5andmodifiedHZSM一5werecharacterizedbymeansofXRD，NH3．TPD，Py．IR,FT-IR,BETan

6、dSEM．TheresultsshowedIII北京化工大学硕士学位论文thatTEOSmainlydepositedontheexternalsurfaceofHZSM-5whichformedSi02aftercalcination．TheacidsitesontheexternalsurfaceofHZSM．5weredeactivatedandtheporeopeningsofHZSM一5werenarrowedbytheformedSi02withoutaffectingtheinternals

7、tructureofHZSM-5．Them--xyleneisomerizationoveracidsandalkalimodifiedHZSM--5waspreliminarydiscussedinthispaper．Theconversionofm—xylenedecreasedbutpara-xyleneselectivityincreasedovertheinorganicacids-treatedHZSM-5．Noeffectwasobservedbyusingtheorganicacid．Th

8、econversionofm-xyleneincreasedbutpara—xyleneselectivitydecreasedonthealkali-treatedHZSM-5，theamountofxylenelosswassignificantlyimproved．AseriesofshapedHZSM一5catalystwithdifferentamountofHN03，differentkindsofhole-exp