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Chemistry. 2015 Oct 19;21(43):15412-20. doi: 10.1002/chem.201501894. Epub 2015 Sep 2.

One-Pot Synthesis of Zeolitic Strong Solid Bases: A Family of Alkaline-Earth Metal-Containing Silicalite-1.

Author information

1
State Key Laboratory of Materials-Oriented Chemical Engineering, College of Chemistry and Chemical Engineering, Nanjing Tech University (former Nanjing University of Technology), Nanjing 210009 (P. R. China).
2
Key Laboratory of Mesoscopic Chemistry of MOE, College of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093 (P. R. China).
3
State Key Laboratory of Materials-Oriented Chemical Engineering, College of Chemistry and Chemical Engineering, Nanjing Tech University (former Nanjing University of Technology), Nanjing 210009 (P. R. China). junwang@njtech.edu.cn.
4
Key Laboratory of Mesoscopic Chemistry of MOE, College of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093 (P. R. China). luming@nju.edu.cn.

Abstract

Fabricating stable strong basic sites in well-preserved crystallized zeolitic frameworks still remains a difficult issue. Here, we reported a family of MFI-type metallosilicate zeolites, AeS-1 (Ae: alkaline-earth metal ions of Mg, Ca, Sr or Ba; S-1: silicalite-1) through a direct one-pot hydrothermal method involving the acidic co-hydrolysis/condensation of the silica precursor with the Ae salts. Step-by-step full characterizations were designed and conducted for in-depth discussion of the Ae status in AeS-1. Strong basicity (H_≈22.5-26.5) was detected in AeS-1. The basicity was further confirmed by CO2 sorption measurements, (13) C NMR spectra of chloroform-adsorbed samples, and (1) H→(13) C and (1) H→(29) Si cross-polarization magic-angle spinning NMR spectra of ethyl cyanoacetate-adsorbed samples. The results of Knoevenagel condensations demonstrated the excellent solid base catalysis of AeS-1, which showed high activity, reusability, and shape-selectivity, all of which are explained by Ae-derived zeolitic intracrystalline strong basic sites.

KEYWORDS:

alkaline-earth metals; heterogeneous catalysis; hydrothermal synthesis; solid bases; zeolites

PMID:
26333165
DOI:
10.1002/chem.201501894

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