Fe/ZSM-5 is a potential methane dehydroaromatization (MDA) catalyst in addition to Mo/ZSM-5. In this study, Fe/ZSM-5 catalysts are prepared via a grinding synthesis method (GSM) using Na2FeO4 as the iron precursor. Iron species in the obtained catalysts are presented mainly as isolated or low-polymerized sites in zeolite cationic exchange positions and pores/channels, generating strong metal–support interactions. These iron species are found to be highly resistant to the reduction and carburization of methane in the MDA reaction, which contradicts common Fe/ZSM-5 catalysts. The rapid formation of active iron suboxides (highly dispersed FeO, Fe3O4 or FeO x ) together with the fast generation of hydrocarbon pool species inside zeolite channels considerably shorten the induction period. Owing to the strong metal–support interaction, the formed iron suboxides could also withstand sintering/agglomeration and inhibit coke accumulation on the external catalyst surface during reaction. While for Fe/ZSM-5 catalysts prepared by the conventional impregnation method, the iron oxides remain principally at the external surface as big clusters/particles with weak metal–support interaction, which then undergo complete reduction and carburization during MDA reaction. The slow formation of active iron carbides and subsequent slow generation of hydrocarbon pool species result in a longer induction period. Moreover, complete dehydrogenation of methane takes place on the iron carbides at the outmost surface of the catalyst, causing massive coke accumulation. Hence, the shortened induction period together with higher coking resistance of GSM Fe/ZSM-5 provide more thought to the design of iron-based MDA catalysts.

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The Ni/SAPO-11 bifunctional catalyst for hydroisomerization of n-hexane was prepared via a novel synthesis method. It involved grinding of nickel source with amorphous precursors used for SAPO-11 followed by crystallization at 473 K for 24 h, thus avoiding the use of extra solvents in the synthesis. The highly dispersed nickel species and acid sites in the Ni/SAPO-11 bifunctional catalyst were instantaneouslyformed. The Ni/SAPO-11 catalyst contains framework nickel, nickel monoxide (NiO) and nickel aluminate spinel. The nickel monoxide with a size of 2-4 nm provides (de)hydrogenation function after reduction, while the framework nickel supplies more acid sites leading to an enhancedisomerization activity.The Ni/SAPO-11 catalyst shows a great synergeticeffect between the metallic nickel and acid sites with a high metal-to-acid sites ratio (C Ni /C A ) and close proximity. A single metallic nickel site is able to balance ca. 5 acid sites (C Ni /C A ≈0.19) over the Ni/SAPO-11 catalyst in n-hexane hydroisomerization.The high dispersion of nickel over the catalyst provides relatively excessive metal sites (C Ni /C A >0.19), leaving the rate limiting reaction to occur on the acid sites. The Ni/SAPO-11 catalyst exhibits comparable n-hexane conversion (71.2%) and iso-hexane yield (66.7%) to the classical Pt/SAPO-11 catalyst.With enhancing acidity, the Ni/SAPO-11 catalyst exhibits one of the highest iso-hexane yields reported in the n-hexane hydroisomerization, which render the new material as a promising candidate for the hydroisomerization catalysts.

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