title: Hydrothermal synthesis and characterization of aluminum-free Mn-β zeolite: a catalyst for phenol hydroxylation.
abstract: Zeolite beta, especially heteroatomic zeolite beta, has been widely used in the industries of fine chemicals and petroleum refining because of its outstanding thermal stability, acid resistance, and unique 3-D open-frame structure. In this paper, aluminum-free Mn-β zeolite was hydrothermally synthesized in the SiO2-MnO2-(TEA)2O-NaF-H2O system. The effect of the chemical composition of the precursor mixture to the crystallization of the Al-free Mn-β zeolite was investigated. The synthesized Al-free Mn-β zeolite was characterized by inductively coupled plasma (ICP), XRD, thermogravimetric/differential thermal analysis (TG/DTA), N2 adsorption-desorption, FT-IR, UV-vis, X-ray photoelectron spectroscopy (XPS), and scanning electron microscope (SEM). The results show that the synthesized zeolite has a structure of β zeolite with good crystallinity and Mn ions present in the framework of the zeolite. The synthesized Al-free Mn-β zeolite shows great catalytic activity toward the phenol hydroxylation reaction using H2O2 as the oxidant. Approximately 35% of phenol conversion and ∼98% of dihydroxybenzene selectivity can be obtained under the optimal conditions.
authors.affiliation: College of Chemistry and Chemical Engineering, Central South University , Changsha, Hunan 410083, P. R. China.
authors.forename: Zhen
authors.initials: Z
authors.lastname: He
authors.forename: Juan
authors.initials: J
authors.lastname: Wu
authors.forename: Bingying
authors.initials: B
authors.lastname: Gao
authors.forename: Hongyun
authors.initials: H
authors.lastname: He
keywords: Al-free; beta zeolite; catalytic activity; hydrothermal synthesis; phenol hydroxylation