预处理条件对Mo／HZSM—5催化剂上丙烷芳构化的影响

采用浸渍法制备了Ｍｏ／ＨＺＳＭ－５ 分子筛催化剂，考察了Ｈ２ 、Ｎ２ 、空气预处理对催化剂丙烷芳构化活性的影响。在相同处理条件下，空气气氛更有利于提高催化剂的丙烷芳构化活性。在空气焙烧过程中，氧化钼物种向分子筛内表面分散。在Ｈ２ 还原处理过程中，表面钼物种部分被还原为Ｍｏ４ ＋ 。随还原时间延长，催化剂芳构化活性升高，同时发生少量Ｍｏ 物种向分子筛孔道内迁移

EFFECT OFPRETREATMENT ATMOSPHERE ONAROMATIZATION OFPROPANEOVER Mo/HZSM- 5 ZEOLITECATALYST

Mo/HZSM- 5 catalysts used for aromatization of propane were prepared by impregnation method- The effectsofpretreatmenttime and atmosphere such as H2,N2,airon catalytic activity and selectivity were investigated- It was found thatthe pretreatmentin air was more favourableforaromaticsthan in H2 or N2 underthe same conditions- For example , the yield ofaromatics and the stability of catalyst were higherthan othertwo catalysts- With the pretreatment time prolonged ,the catalytic activity and stability were enhanced in H2- XRDresultindicatedthat molybdenum oxidespecies dispersed onthe surface ofzeolite during the calcination in air,which cause the disappearance of diffraction peak of MoO3- XPSand TPRstudies demonstratedthat Mo speciesexisted as Mo6 aftercalcinationin airand reduced to Mo4 partly with a little ofthem migrated to the channel of HZSM- 5 during reduction- Maybe the Mo4 specieslocated in channel were activefor aromatization of propane-