PETR 60 |
| ZSM-5 deactivates differently from Y zeolite. Dealumination of Y zeolite during deactivation causes UCS shrinkage and thereby decline in activity and changes in selectivity. For ZSM-5 instead deactivation removes Al from the zeolite structure, but the zeolite structure does not collapse. Therefore deactivation causes activity decline due to loss of active Al sites, but no significant changes in the strength and separation between acid sites. Unlike with FCC catalyst, physical properties of ZSM-5 additive do not change significantly with deactivation and surface area and pore volume measurements cannot be used as indications of additive performance. Yet, since both Y and ZSM-5 are used simultaneously in practice, the information on the relative rates of deactivation between the two zeolites is very important. Therefore the question remains, what is the best way to deactivate and test ZSM-5 additives in laboratory to obtain realistic performance e.g. propylene yield and to obtain proper ranking of various additives. This paper discusses the effect of deactivation conditions as well as performance testing aspects of ZSM-5 additives.
|
|
Catalysis and Chemistry for the Synthesis of Fuels, Chemicals and Petrochemicals
1:15 PM-4:25 PM, Monday, August 20, 2007 Boston Park Plaza -- Plaza Ballroom, Oral
Division of Petroleum Chemistry |