Dealuminated mordenite, toluene

Gnep et al. (91) investigated toluene disproportionation and coke formation over chemically dealuminated mordenite. 

They found that aluminum-deficient mordenite (SiO /Al O ratio of 18), pre-calcined in a flow of dry air, is twice as active for toluene disproportionation and coke formation as compared to regular mordenite. The aluminum-deficient form also has a higher rate of deactivation. It is assumed that the formation of new, strong acid sites during the process of moderate dealumination is responsible for the observed change in activity. 

Holderich et al. obtained high yields (up to 81 %) of keto aldehyde (13) over H-FER after 6 h in the liquid phase at 110 °C with toluene as solvent [37]. H-US-Y catalysts perform well in the formation of (13). The H-US-Y (Si/Al = 48)-HCl catalyst, modified by treatment with dilute HCl (pH 2) according to the method described in the preceding section [35,38] is particularly active, even at high weight hourly space velocities. The performance of this catalytic system is comparable with that of the system described by Sheldon et al. [36]. Reaction in benzene at 80 °C for 2 h over dealuminated H-mordenite gave 100% conversion and 85 % selectivity for (13). The ratio of the two main products (13) and (14) depends on the type and acidity of the zeolite used. For example, H-BEA with a more acidic outer surface was highly active but the selectivity for (13) was lower than for H-FER or H-US-Y catalysts [37]. 

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