Πανεπιστήμιο Ιωαννίνων. Σχολή Θετικών Επιστημών. Τμήμα Χημείας
(EL)
Katranas, T. K.
(EN)
This study reports results of propane transformation over the natural microporous manganese oxide, todorokite, and its hydrogen form (H-Todorokite), at the temperature range of 350degrees-550 degreesC. Both materials were fully characterized and their catalytic results were compared with results obtained with commercial Ultra-Stable-Y (USY), and steamed H-ZSM-5 zeolite catalysts. The natural todorokite sample shows appreciable dehydrogenation activity (propylene yield similar to8%, selectivity to propylene >31%), considerably higher compared to H-ZSM-5 zeolite. This is justified by the absence of strong acid sites and the presence of a large amount of ion-exchangeable cations, which induce the dehydrogenation capability of the material. The proton-exchanged form of todorokite, appears to act as a very efficient cracking catalyst (yield to methane and ethylene similar to40%, selectivity to cracking products >85%), due to the formation of a large number of framework Bronsted acid sites. The observed cracking capability of H-todorokite is superior to the activity of the commercial fluid catalytic cracking (FCC) USY catalyst, thus suggesting that the proton form of the mineral is a promising catalyst for the cracking of small alkanes. (C) 2004 Elsevier Inc. All rights reserved.
(EN)
