摘要
为了详尽定性和定量分析ZSM-35分子筛孔道内部和外部的酸中心,对在不同焙烧晶化条件下制备的3种ZSM-35分子筛样品(编号分别为GNJ,GNX,GW)采用NH3-TPD和吸附不同探针分子的31P MAS NMR谱进行表征,并在微反装置上对3种样品进行催化正丁烯异构化反应性能评价。结果表明:ZSM-35分子筛中Brnsted酸酸量远多于Lewis酸酸量,且不同制备方法得到的ZSM-35分子筛Brnsted酸强度与酸量不同;GNJ主要有1种弱Brnsted酸中心,GW有3种不同强度的Brnsted酸中心,较弱的Brnsted酸中心在孔道内部和外部均有分布,较强的两种Brnsted酸中心主要分布在孔道内部;GNX有两种不同强度的Brnsted酸中心,在孔道内部和外部均有分布,且GNX的Brnsted酸酸量高于GNJ和GW;催化正丁烯异构化反应时,ZSM-35分子筛的中强Brnsted酸中心是异丁烯生成的必要酸中心,且中强Brnsted酸中心更有利于异丁烯的生成,因此制备具有合适的中强Brnsted酸强度和酸分布的ZSM-35分子筛有利于正丁烯异构化反应的进行。
In order to determine qualitatively and quantitatively the internal and external acid sites of the ZSM-35 zeolites,three types of ZSM-35 samples(GNJ,GNX,GW)prepared under different crystallization and calcination conditions were characterized using NH3-TPD and 31P MAS NMR of adsorbing different probe molecules.Simultaneously the selectivity and activity of the isomerization of n-butene on different catalysts were analyzed.The results showed that the amount of Brnsted acid site in ZSM-35 zeolites were much more than Lewis acid site,the acid strength and amount on ZSM-35 zeolites were different according to preparation methods.GNJ had a kind of weak Brnsted acid,GW had three kinds of Brnsted acid sites of different strengths,the weaker Brnsted acid sites were distributed inside and outside the channel and the stronger two kinds of Brnsted acid sites were mainly distributed inside the channel.GNX had two kinds of Brnsted acid sites of different strengths,which were distributed inside and outside the channel.Brnsted acid amount of GNX was more than the other two samples.When catalyzing the isomerization of n-butene,it was found that the medium strong Brnsted acid site was an essential acidic site for isobutene formation and it was more conducive to the formation of isobutylene.Therefore,the preparation of ZSM-35 molecular sieve with appropriate suitable medium-strong Brnsted acid strength and acid distribution was beneficial to the progress of the n-butene isomerization reaction.
作者
刘晓华
黄文氢
满毅
宋建会
柳颖
Liu Xiaohua;Huang Wenqing;Man Yi;Song Jianhui;Liu Ying(SINOPEC Beijing Research Institute of Chemical Industry,Beijing 100013)
出处
《石油炼制与化工》
CAS
CSCD
北大核心
2020年第8期56-61,共6页
Petroleum Processing and Petrochemicals