TY - JOUR
T1 - The promoting effects of alkali metal oxide in side-chain alkylation of toluene with methanol over basic zeolite X
AU - Han, He
AU - Liu, Min
AU - Nie, Xiaowa
AU - Ding, Fanshu
AU - Wang, Yiren
AU - Li, Junjie
AU - Guo, Xinwen
AU - Song, Chunshan
N1 - Publisher Copyright:
© 2016 Elsevier Inc.
PY - 2016/11/1
Y1 - 2016/11/1
N2 - The side-chain alkylation of toluene with methanol was investigated on a series of catalysts which were prepared by ion-exchange or subsequent impregnation of zeolie X with potassium hydroxide or cesium hydroxide aqueous solution. The catalysts were characterized by X-ray diffraction, scanning electron microscopy, X-ray fluorescence, Ar physical adsorption-desorption, NH3 temperature-programmed desorption (TPD), CO2-TPD, pyridine adsorption Fourier-transform infrared (FT-IR) spectroscopy, FT-IR spectroscopy in [Formula presented] stretch region, thermogravimetric/differential thermal analysis, ultraviolet-Raman spectroscopy, and X-ray photoelectron spectroscopy. It was found that alkali metal oxide played extremely important roles in the modification of catalysts and in the catalytic reaction pathway. Strong basic sites were formed by modification of basic zeolite X with alkali metal oxide. These basic sites promoted the dehydrogenation of methanol to formaldehyde which was recognized as the true alkylating agent in side-chain alkylation. Consequently, side-chain alkylation of toluene with formaldehyde was enhanced. As toluene was mainly adsorbed and activated on alkali metal cations bonded on the zeolite framework, the synergistic effects between alkali metal oxide and alkali metal cations were proposed. One of the possible reaction path ways for side-chain alkylation of toluene with methanol over basic zeolite was described. Alkali metal ion-exchanged zeolite X modified with alkali metal oxide demonstrated relatively high side-chain alkylation activity. However, the improvement of styrene selectivity faced with great challenges.
AB - The side-chain alkylation of toluene with methanol was investigated on a series of catalysts which were prepared by ion-exchange or subsequent impregnation of zeolie X with potassium hydroxide or cesium hydroxide aqueous solution. The catalysts were characterized by X-ray diffraction, scanning electron microscopy, X-ray fluorescence, Ar physical adsorption-desorption, NH3 temperature-programmed desorption (TPD), CO2-TPD, pyridine adsorption Fourier-transform infrared (FT-IR) spectroscopy, FT-IR spectroscopy in [Formula presented] stretch region, thermogravimetric/differential thermal analysis, ultraviolet-Raman spectroscopy, and X-ray photoelectron spectroscopy. It was found that alkali metal oxide played extremely important roles in the modification of catalysts and in the catalytic reaction pathway. Strong basic sites were formed by modification of basic zeolite X with alkali metal oxide. These basic sites promoted the dehydrogenation of methanol to formaldehyde which was recognized as the true alkylating agent in side-chain alkylation. Consequently, side-chain alkylation of toluene with formaldehyde was enhanced. As toluene was mainly adsorbed and activated on alkali metal cations bonded on the zeolite framework, the synergistic effects between alkali metal oxide and alkali metal cations were proposed. One of the possible reaction path ways for side-chain alkylation of toluene with methanol over basic zeolite was described. Alkali metal ion-exchanged zeolite X modified with alkali metal oxide demonstrated relatively high side-chain alkylation activity. However, the improvement of styrene selectivity faced with great challenges.
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U2 - 10.1016/j.micromeso.2016.06.045
DO - 10.1016/j.micromeso.2016.06.045
M3 - Article
AN - SCOPUS:84978924854
SN - 1387-1811
VL - 234
SP - 61
EP - 72
JO - Microporous and Mesoporous Materials
JF - Microporous and Mesoporous Materials
ER -