How do the products in methane dehydroaromatization impact the distinct stages of the reaction?

Methane dehydroaromatization reaction at 700 °C over Mo/ZSM-5 involves numerous modifications of the molybdenum species from catalyst preparation and throughout lifetime, composed 4 successive steps: calcination, activation, induction, deactivation. A thorough kinetic study was undertaken with aim to understand transformation phenomena occurring on during each stage reaction, using methane gas hourly space velocity per gram (M-GHSV) 1 29 L CH4 h ?1 g cat . Here from, unexpected behaviors were observed, supported by molecular modeling results. MoO 3 firstly reacts stoichiometrically calcination (?rH =0.86 eV) bridged hydroxyl pairs yielding [Mo 2 O 5 ] 2+ (calcination). Thereafter, slowly reduces form C (activation). The latter converts ethylene (E = 1.49 eV), which dimerizes two times faster butene through hydrocarbon pool catalysis rather than Brønsted acid sites (induction). deactivates an inhibition effect aromatics, adsorb strongly onto (?H ads ~ 0.7 (deactivation). large amount autogenous hydrogen produced lower allows preventing active poisoning, leading slower deactivation rate. • Mo/HZSM-5 a strong aromatics. Soft coke proton sites. H2 acts as surface scavenger promoting desorption aromatic compounds.