Cd-ZSM-5沸石的结构稳定性和积炭-烧炭特性  

Structure stability and coking─decoking behavior of Cd-ZSM-5 zeolite catalyst

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作  者:侯玉翠[1] 王定珠[1] 卢学栋[1] 

机构地区:[1]中国科学院山西煤炭化学研究所煤转化国家重点实验室,轻工部太原日用化学研究所

出  处:《天然气化工—C1化学与化工》1994年第5期11-14,共4页Natural Gas Chemical Industry

基  金:中国石化总公司资助

摘  要:用热分析方法研究了Cd改性ZSM-5沸石催化剂(Cd-ZSM-5)的结构稳定性和积炭-烧炭特性,发现上述性质和制备因素密切相关.结果表明,在500℃以上氢气中,Cd(11)被还原成金属Cd,并逐渐流失,其稳定性随制备方法而变,按交换法>浸渍法>混合法顺序下降。这种变化可与Cd状态(Cd2+和CdO)分布不同,以及它们的还原性不同相关联,Cd2+离子与沸石间的强相互作用使其较之CdO难以还原。改性沸石的积炭初速率是交换法<混合法<浸渍法,且随Cd增加而增加。以离子交换0.6%Cd样品的结构稳定性最好,积炭初速率也最低。Cd改性使烧炭活化能提高,烧炭活化能按交换法、浸渍法、混合法次序递增,且随Cd增加而增加。Structure stability and coking-decoking behaviorof thd Cd-omodified ZSM-5 zeolite catalysts (Cd-ZSM-5) have been studied thermogravinetrically, and fond closely relative to preparation factors. The results show that Cd (II) species on thde catalyst is reduced to the metal form and lost gradually in flowing H2 at temperatures above 500℃. The stability of Cd (II) is changed with modifying methods, following the order ino-exchange (E) > impregnation (I) >mixing (M),which can be considered in correlation with the variations of distribution of two Cd (II ) species (Cd2+ and CdO) and of their reducibilities. Cd2+ is strongly interacted with the acidic OH groups of thd zeolite,resulting in a more difficult re-duction of Cd2+ than that of CdO.The initial coking rate of Cd-ZSM-5 is varide in the order E <M <I, and also increases with Cd loading on the catalyst. An ionexchanged catalyst with Cd as low as 0. 6% is preferred with a highest structure stability and a lowest initial coking rate. Modified by Cd,the activation energy of decoking is increased in the order E<I<M and also with the increase of Cd loading.

关 键 词:镉沸石 稳定性 积炭 烧炭 

分 类 号:TE624.9[石油与天然气工程—油气加工工程]

 

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