ON THE ENHANCED DEHYDROGENATION VERSUS CRACKING ABILITY OF AN ACIDIC GALLIUM MFI - A TENTATIVE ACID-BASE INTERACTION-MODEL

被引:31
作者
BANDIERA, J [1 ]
TAARIT, YB [1 ]
机构
[1] INST RECH CATALYSE, CNRS, 2 AVE ALBERT EINSTEIN, F-69626 VILLEURBANNE, FRANCE
来源
APPLIED CATALYSIS | 1991年 / 76卷 / 02期
关键词
ACIDITY; ALKANES; CRACKING; DEHYDROGENATION; GALLIUM MFI; ZEOLITES;
D O I
10.1016/0166-9834(91)80047-Z
中图分类号
O64 [物理化学(理论化学)、化学物理学];
学科分类号
070304 ; 081704 ;
摘要
The hydrogenation and cracking properties of an authentic H(Ga)-MFI are investigated in a true kinetic regime. The cracking of propane over the H(Ga)-MFI decreased dramatically in comparison to results obtained over a comparable H(Al)-MFI. Conversely, the dehydrogenation of propane was very much increased. The Bronsted acid sites associated with the framework gallium seem to operate in a similar manner to those associated with framework aluminium in H(Al)-MFI. However, since their strength is attenuated, their greater dehydrogenation activity is ascribed to their preferred reaction with a C-H sigma-bond of propane to form the carbonium ion with respect to a C-C sigma-bond, while the reverse situation prevails with the stronger acid sites of H(Al)-MFI. A kind of soft-soft and hard-hard acid-base interaction is thought to govern the formation of carbonium ions having distinct structures which lead, respectively, to cracking or dehydrogenation.
引用
收藏
页码:199 / 208
页数:10
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