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1、物理化学学报(WuliHuaxueXuebao)672ActaPhys.-Chim.Sin.,2006,22(6):672～678June[Article]www.whxb.pku.edu.cnNa对PtSn/ZSM-5催化丙烷脱氢反应性能的影响张一卫1周钰明1*邱安定2,3王玉2,3许艺2吴沛成2(1东南大学化学化工学院,南京210096;2南京烷基苯厂催化事业部,南京210046;3南京大学化学化工学院,南京210093)摘要以HZSM-5分子筛为载体,利用分步浸渍法制得不同Na含量的PtSnNa/ZSM-5催化剂,用于丙烷
2、脱氢反应.利用XRD、吡啶吸附红外光谱、NH3-TPD、氢化学吸附、TPR等手段,研究了Na的添加对PtSn/ZSM-5催化剂物化性质的影响.结果表明:Na的添加对PtSn/ZSM-5催化剂的反应性能影响明显.适量Na的添加不仅降低了催化剂中的Br#nsted酸中心和Lewis中强/强酸中心,抑制了积碳的发生,提高了催化反应的稳定性;而且提高了催化剂表面的Pt金属裸露度,增加了反应活性.当Na含量为1.0%(w)时,催化剂的丙烯选择性和收率达到最大,反应30h后,丙烷转化率仍然保持很高(36.4%).继续增加Na含量,催化剂中的
3、Lewis弱酸中心有所增加,同时Sn组分易于被还原成Sn0,丙烷裂解、氢解等副反应增加,不利于脱氢反应的进行.关键词:ZSM-5,铂,钠,丙烷脱氢,丙烯,催化剂中图分类号:O643EffectofNaAdditiononCatalyticPerformanceofPtSn/ZSM-5CatalystforPropaneDehydrogenation11*2,32,3ZHANG,Yi-WeiZHOU,Yu-MingQIU,An-DingWANG,Yu22XU,YiWU,Pei-Cheng(1CollegeofChemistryan
4、dChemicalEngineering,SoutheastUniversity,Nanjing210096,P.R.China;2OfficeofCatalyticEnterprise,NanjingLinearAlkylBenzenePlant,Nanjing210046,P.R.China;3CollegeofChemistryandChemicalEngineering,NanjingUniversity,Nanjing210093,P.R.China)AbstractPtSnNa/ZSM-5catalystswithd
5、ifferentamountsofNawerepreparedbythesequentialimpregnationmethodonHZSM-5zeolites,andtheircatalyticactivitiesandstabilitiesinpropanedehydrogenationwereinvestigated.TheeffectoftheadditionofsodiumonthephysicochemicalpropertieswasstudiedbymeansofXRD(X-raydiffration),IRsp
6、ectrumofadsorbedpyridine,NH3-TPD,H2chemisorption,TPR(temperature-programmedreduction),etc.TheresultsindicatedthattheadditionofNahadanobviousimpactonthecatalyticperformanceofthePtSn/ZSM-5catalyst.AsuitableconcentrationofNacouldnotonlyreducetheBr$nstedacidsitesandmoder
7、ate/strongLewisacidsites,thuspreventingthecatalystfromcokingandimprovingthecatalyticstability,butalsoincreasethefractionofbaremetallicPtonthesurfaceofthecatalyst,thusincreasethecatalyticactivity.Itwasfoundthatthepropeneselectivityandyieldcouldreachthemaximum,whentheN
8、acontentwas1.0%(w).Afterreactionfor30h,thepropaneconversionwasstillhigh(36.4%).However,thecontinuousadditionofNaincreasedtheweakLew
