TADP of toluene

[rgrokkam]

Dear all,
What does transalkylation disproportionation of toluene (stream from Benzene-toluene fractionator) result in?
What is the reaction?
Thanks

 

[EmmanuelTop]

"The main products of the transalkylation between two toluene molecules are benzene and xylenes, but different undesirable reactions such as the disproportionation of xylene, alkyl benzene dealkylation and cracking can occur. In the first industrial disproportionation processes, Friedel-Crafts (AlCl.sub.3) catalysts were used, the xylenes being obtained in the thermodynamic equilibrium proportion, on which temperature has a slight influence. The equilibrium limits can be exceeded for the reaction when shape-selective zeolite catalysts having a selective molecular diffusion effect are used, especially when appropriately-processed ZSM-5 is used. In this regard, major degrees of selectivity for para-xylene have been achieved in commercial processes, with the corresponding positive impact on the process economics."

Source:

http://www.freshpatents.com/Method-...ganic-compounds-dt20080124ptan20080021253.php

http://antwrp.gsfc.nasa.gov/apod/astropix.html