Role of Water in the Kinetic Modeling of Methanol Transformation Into Hydrocarbons on HZSM-5 Zeolite

Reaction pathway and kinetics of C3–C7 olefin transformation over high-silicon HZSM-5 zeolite at 400–490°C

“…In addition, water existed in the reactant mixture due to dehydration of the used alcohols, somewhat analogous to the practice where water is co-fed to dilute the reactant and prolong catalyst lifetime [16,33]. FT-IR studies and theoretical calculations [34,35] showed that water adsorbed on the active site through H-bond with the acidic -OH group on the zeolite, thus occupied a portion of active sites [36,37].…”

Kinetics of methanol to olefins over AlPO4-bound ZSM-5 extrudates in a two-stage unit with dimethyl ether pre-reactor

“…An acceleration of cracking reactions to propylene with increasing temperature can be assumed, which is in good agreement with the proposed dualcycle concept mentioned above. The importance of cracking reactions to propylene can also be seen in most of the kinetic models proposed in the last years [17][18][19]. The consideration of cracking of higher hydrocarbons to light olefins in the reaction scheme is necessary for the reproduction of the experimental data.…”

“…Most models have been proposed for MTG-process conditions with temperatures below 400°C [11][12][13]30,31]. Furthermore, the simplification of the kinetic scheme does not allow the differentiation of the light olefins, because they were grouped together [11][12][13][14][15]17,18]. Models proposed for MTOprocess conditions (>400°C) have been developed by using shaped zeolites with high acidity (Si/Al-ratio low) [17,18].…”

“…Most of the proposed models have been tested at temperatures below 400°C, in the MTG-process regime. However, Gayubo et al developed a kinetic model for a temperature range up to 450°C, taking into account cracking reactions to light olefins [17]. A further model by Aguayo et al quantifies the product distribution at even higher temperatures (400-550°C), but it has been developed for the CMHC process (coupled methanol and hydrocarbons cracking), in which zeolites with high total acidity are used [18].…”

“…In most studies, shaped catalysts were employed consisting of zeolite as the active phase and aluminum-containing binder materials like bentonite, kaolin and alumina [11][12][13][14][15][17][18][19]. However, it cannot be excluded in general that the density of acid sites may change with the use of such binder materials.…”