On the Induction Period of Methane Aromatization over Mo-Based Catalysts

Methane dehydroaromatization over Mo/HZSM-5 catalysts: The reactivity of MoCx species formed from MoOx associated and non-associated with Brönsted acid sites

“…Ichikawa and coworkers attributed the low-temperature peak to a reactive coke associated with Mo 2 C and the high-temperature one to irreversible or inert coke [60]. In our continuing studies on the carbonaceous deposits from the TPO profiles of the 6Mo/TiO 2 and the 6Mo/MCM-22 after MDA reaction at 973 K for 3 h [61,62], we found that the 6Mo/MCM-22 gave a doubled peak located at 742 and 830 K, respectively. Meanwhile, only one peak corresponding to the carbonaceous deposits The calculation is based on the assumption that the activation and dehydrogenation of methane on Mo carbide species is the rate-determining step in the MDA reaction.…”

The chemical nature of carbonaceous deposits and their role in methane dehydro-aromatization on Mo/MCM-22 catalysts

“…It is interesting to notice that the peak areas corresponding to CH 4 formation are getting smaller and smaller, while the CH 4 peak temperature remains constant with the increase of the Mo loading. Most researchers confirmed that Mo species migrate into the channel of zeolite and interact with the Brönsted acid sites [17]. The more Mo species introduced into the zeolite, the fewer the free Brönsted acid sites left in the channels [39].…”

Direct conversion of methane under nonoxidative conditions

“…Bao and co-workers, using TPSR of CH 4 , clearly demonstrated that there is an induction period for the Mo-based catalysts in an early stage of MDA [45]. In their study of in situ 1 H MAS NMR spectroscopy of proton species over Mo/HZSM-5 catalysts during the reactions of CH 4 , they reported that when the temperature was at or below 873 K, only a small decrease in the Brønsted acidity could be observed due to the temperature effect [46].…”