N-Dodecane Hydroisomerization over Hierarchical ZSM-22 Prepared by a Dual-Protected Alkali Treatment

Abstract

In this work, a series of hierarchical ZSM-22 zeolites are prepared by a dual-protected alkali treatment route in the presence of microporous and mesoporous templates. The pore structure and acidity of hierarchical ZSM-22 zeolites are tailored by partial detemplation and addition of cetyltrimethylammonium bromide (CTAB), which are characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, inductively coupled plasma, N2 adsorption–desorption, temperature-programmed desorption of NH3, Py-IR, Lu-IR, and 27Al magic-angle spinning nuclear magnetic resonance. The retained microporous templates after partial detemplation keep the ZSM-22 rod-like morphology in the alkali treatment. CTAB effectively introduces uniform mesoporosity centered at ca. 3.2 nm. As a result, as-prepared hierarchical ZSM-22 (430ATC) contains a large amount of small mesopores and pore-mouths, and higher desilication efficiency is achieved. After loading 0.5 wt % Pt, this hierarchical ZSM-22 supported...