Autochem 2 2920 chemisorption analyzer

Powder X-ray diffraction (XRD) patterns were collected on a Rigaku MiniFlex II X-ray diffractometer (Rigaku, Tokyo, Japan) with Cu Kα radiation (30 kV and 15 mA) at a scanning speed of 4°/min. The relative crystallinity of the P/ZSM-5 catalyst was estimated by comparing the total peak area in the range of 2θ from 7° to 10° and 22° to 25° with that of the parent HZSM-5. The specific surface area, pore size distribution, and pore volume were measured at 77 K on a BELSORP-max gas adsorption analyzer (MicrotracBEL, Osaka, Japan). The actual amount of zinc element in the Zn/ZSM-5 zeolites was determined by inductively-coupled plasma atomic emission spectroscopy (ICP-AES, Autoscan16, TJA, Boston, MA, USA). The ²⁷Al magic angle spinning nuclear magnetic resonance (²⁷Al MAS NMR) spectra were recorded on Bruker Avance III 600 spectrometer (Bruker, Karlsruhe, Germany) with 1.0 M aqueous solution of Al(NO₃)₃ as the reference at 104.3 MHz. Infrared spectra for pyridine adsorption (Py-IR, Tensor 27 FT-IR spectrometer, Bruker, Karlsruhe, Germany) and temperature-programmed desorption of NH₃ (NH₃-TPD, AutoChem II 2920 chemisorption analyzer, Micromeritics, Atlanta, GA, USA) were performed by following similar procedures with the same instrument as reported previously [33 (link),48 (link)].

Transmission electron microscope (TEM, Tecnai TM G2 F30, FEI, USA) was employed to reveal the surface reconstruction of the as-synthesized catalysts. The surface morphology and microstructure of catalysts was probed by scanning electron microscopy (SEM, Thermo Scientific, Apreo S). X-ray diffraction (XRD, X’ Pert PRO PHILIPS with Cu Kα radiation) and Raman spectrometer (Lab-RAM HR Evolution) were carried out to decide the phase structure. The cation amounts of the samples were detected by an inductively coupled plasma optical emission spectrometer (ICP-OES, Agilent 5110, USA). The elemental composition and the valence state of the catalysts were studied by X-ray photoelectron spectroscopy (XPS, Kratos Axis Ultra). Elemental spectra and mappings were obtained by an energy-dispersive spectrum analyzer (EDS, Bruker SuperX). Temperature programmed desorption of oxygen gas (O₂-TPD) was measured with a Micromeritics AutoChem II 2920 chemisorption analyzer. In addition, microscopy images, selected area electronic diffraction (SAED) patterns, elemental mapping, and linear scanning analysis were explored with Titan Gubed Themis G2300 scanning/transmission electron microscopes.