Conversion of methanol over 10-ring zeolites with differing volumes at channel intersections: comparison of TNU-9, IM-5, ZSM-11 and ZSM-5

Abstract

Four 3D 10-ring zeolites, IM-5, TNU-9, ZSM-11 and ZSM-5, with Si/Al = 14-24 and crystal sizes below 2 microns, were tested as catalysts for the methanol to hydrocarbons reaction (MTH) at atmospheric pressure, 350 °C and WHSV = 9 h(-1). All catalysts gave initially full methanol conversion, and showed strikingly similar effluent product selectivities. However, their life-time duration differed significantly, and decreased in the order: ZSM-11 > ZSM-5 ≫ TNU-9 > IM-5. A main difference between the two groups of stability behaviour was the size of cavities formed by channel intersections; larger cavities in TNU-9 and IM-5 leading to polyaromatics formation and a more rapid deactivation compared to ZSM-5 and ZSM-11. Effluent yield-conversion plots suggested that polymethylated benzene intermediates were more important in IM-5 and TNU-9 than in ZSM-5 and ZSM-11, where alkene methylation and cracking reactions seemed to dominate product formation. However, this difference had only minor influence on effluent selectivity.

Morphology-induced shape selectivity in zeolite catalysis

“…One report concerning methanol dehydration into dimethyl ether exists for SZR [43]. During these systematic studies of the effects of zeolite topology on catalyst performance in the MTH reaction [13,44], we have encountered two separate instances where the catalyst performance is determined predominantly by particle morphology, and in particular, how the framework topology is structurally related to the morphology. These observations were made for the SZR (SUZ-4) and MFS (ZSM-57) catalysts.…”

Nature and Location of Carbonaceous Species in a Composite HZSM-5 Zeolite Catalyst during the Conversion of Dimethyl Ether into Light Olefins

“…The performance of high-silica HZSM-5 zeolite reaches a compromise between the light olefin selectivity, and an extended catalyst lifetime [14]. This behavior has been associated with its unique acid and textural properties [15][16][17][18]. In this sense, HZSM-5 zeolite displays acid sites of relatively weak strength nature and a three-dimensional porous network with two groups of interconnected channels: ellipsoidal 5.3 × 5.6 Å and sinusoidal 5.1 × 5.5 Å and without cages at intersections.…”

Reactivity of Ga2O3 Clusters on Zeolite ZSM-5 for the Conversion of Methanol to Aromatics

“…18 to 30 % (Tables 5, 6), although a higher amount of dimethylether (DME) was also detected. This enables the effect of the zeolite structure to be investigated, because zeolite ZSM-5 is a pentasil phase consisting of two 26], and rings made of 10 T-atoms units, while zeolite-b has rings of 12 T-atoms with a size of 6.8 Å . This affects the selectivity to aromatics, regardless of the different acidic nature of the zeolite used, as zeolite-b is capable of promoting the formation of alkenes, such as isobutene [27], which could be involved in the dehydrogenation process leading to aromatics [18].…”