Effect of aluminium distribution in the framework of ZSM-5 on hydrocarbon transformation. Cracking of 1-butene

Controlling coke deactivation and cracking selectivity of MFI zeolite by H3PO4 or KOH modification

“…Ethylene selectivity is relatively lower than propylene selectivity, which allows obtaining a propylene/ethylene ratio of 3.1 in the case of HZ280 catalyst. Dědeček et al [70] and Sazama et al [39] have indicated that the local distribution of Al in the framework has a significant effect on the side reactions.…”

“…In addition, the transformation of 1-butene into other more interesting light olefins is an alternative to the oligomerization for the production of middle distillates [36]. The literature reports the complexity of the 1-butene cracking reaction scheme (including oligomerization-cracking, dehydrogenation-aromatization and hydrogen transfer reactions) [37,38] and the significant effect of MFI zeolite properties on product distribution and stability [5,31,39]. Lin et al [40] proposed several reaction pathways for the catalytic cracking of 1-butene on MFI zeolites and established an optimum amount of acid sites (0.181 mmol g -1 ) in order to achieve high propylene selectivity.…”

“…Furthermore, the local Al distribution in the MFI framework affects the product composition during olefin cracking [39].…”

Theoretical Study of the Adsorption of the Butanol Isomers in H-ZSM-5

“…37,38 For ZSM-5 samples with low Si/Al ratios (Si/Al < 45), that is, more than 2 Al per unit cell, the distribution of aluminum atoms exhibits insignificant effect on the acid strength of the zeolites. 39 Therefore, we select the "intersection" site Al12ÀO24(H)ÀSi12 to represent the Brønsted acid site because it is considered among the most stable sites for Al substitution 38,40,41 and has been chosen as the active site for several reactions. 24,25,41À43 Moreover, the intersection site provides maximum reaction space and easy access for reactants, especially bulky ones.…”

3D Nanoscale Chemical Imaging of the Distribution of Aluminum Coordination Environments in Zeolites with Soft X‐Ray Microscopy

“…[5,6] Despite that these are well-known phenomena, further information on aluminum zoning within individual zeolite particles is needed. It is important to recall that the performance of a catalytic material is directly related to the spatial distribution of its active sites, [7][8][9][10] which in the case of zeolites, are the Brønsted acid sites, formed by the corner-sharing of aluminum and silicon tetrahedra. The strength of these Brønsted acid sites are therefore directly related to the number and distribution of aluminum atoms in the zeolite particle.…”