Disproportionation of Trimethyl Benzenes over Large Pore Zeolites: Catalytic and Adsorption Study

0000309 - ÚFCH JH 2005 RIV NL eng J - Journal Article
Čejka, Jiří - Kotrla, Josef - Krejčí, Andrea
Disproportionation of Trimethyl Benzenes over Large Pore Zeolites: Catalytic and Adsorption Study.
[Disproporcionace trimethyl benzenů na širokoporézníích zeolitech: katalytická a adsorpční studie.]
Applied Catalysis A - General. Roč. 277, 1/2 (2004), s. 191-199. ISSN 0926-860X. E-ISSN 1873-3875
R&D Projects: GA ČR GA104/99/0840; GA AV ČR IBS4040015
Institutional research plan: CEZ:AV0Z4040901
Keywords : trimethyl benzenes * xylenes * tetramethyl benzenes * disproportionation
Subject RIV: CF - Physical ; Theoretical Chemistry
Impact factor: 2.378, year: 2004

The effect of the structure of large pore zeolites of Mordenite, beta, L and Y types on the activity, selectivity to xylenes and time-on-stream stability was investigated in trimethyl benzene disproportionation. Significant differences in conversion and time-on-stream stability were observed among individual zeolites. Zeolite beta and zeolite Y were found to exhibit the highest stability in conversion of trimethyl benzenes, while zeolite L and Mordenite were deactivated much faster. The optimum reaction conditions to achieve a high and stable conversion with sufficient selectivity to xylenes were at the reaction temperature of 400 degreesC with WHSV = 5-20 h(-1). Diffusion coefficients of trimethyl and tetramethyl benzenes over zeolites Y, beta and Mordenite at 25 degreesC were determined. Due to the significant differences in diffusion of individual trimethyl and tetramethyl benzenes, it is expected that diffusion of these molecules substantially influence the rate of this reaction.

Byl studován vliv struktury širokoporézních zeolitů Y, Beta, L and mordenitu na aktivitu, selektivitu na xyleny a časovou stabilitu při disproporcionaci trimethylbenzenů. Mezi jednotlivými zeolity byly shledány zásadní rozdíly. Nejvyšší aktivitu a časovou stálost vykazovaly zeolity Y a Beta zatímco mordenit a zeolit L se velmi snadno deaktivovaly. Nejvyšší stabilita konverze při rozumné selektivitě na xyleny byla dosažena při 400 oC a WHSV = 5-20 h-1. Na studovaných zeolitech byly změřeny též difuzní koeficienty trimethylbenzenů a tetramethylbenzenů, které potvrdily rozdílnou rychlost transportu reaktantů a produktů. Navíc tyto experimenty prokázaly rozdílnou dostupnost katalyticky aktivních center v kanálech jednotlivých zeolitů
Permanent Link: http://hdl.handle.net/11104/0000289