Effects of alkaline-earth metals on the structure, adsorption and catalytic behavior of iron-based Fischer–Tropsch synthesis catalysts

Authors: Jifan Li, Chenghua Zhang, Xiaofan Cheng, Ming Qing, Jian Xu, Baoshan Wu, Yong Yang, Yongwang Li

Abstract:
Effects of alkaline-earth metals (magnesium, calcium, strontium and barium) on the physico-chemical properties and Fischer–Tropsch synthesis (FTS) performances of precipitated Fe/SiO₂ catalysts were investigated by N₂ physisorption, laser Raman spectroscopy, FT-IR spectroscopy, in situ X-ray diffraction, Mössbauer effect spectroscopy, temperature programmed reduction or desorption and fixed-bed reactions. The characterization results indicated that alkaline-earth metals strengthened Fe O bonds of Fe₂O₃ in as-prepared catalysts, which consequently inhibited the reduction of catalysts under H₂ atmosphere. Mg and Ca suppress the carbonization of catalysts while Sr and Ba enhance the carbonization. The H₂ adsorption was suppressed while the CO adsorption was enhanced by alkaline-earth metals. In the FTS reaction, alkaline-earth metals had no apparent influence on the CO conversion of catalysts, whereas they suppressed the formation of methane and enhanced the selectivities to olefin and higher molecular weight products. Among these alkaline-earth metals, Sr has the most pronounced influence on inhibiting the light hydrocarbon production. Furthermore, the increased Sr content can further restrain the formation of light hydrocarbons.

Keywords:
Fischer–Tropsch synthesis
Iron-based catalyst
Alkaline-earth metals
Magnesium
Calcium
Strontium
Barium

Published in: Applied catalysis A: General  (Volumes 464–465, Pages 1-384, 15 August 2013)

Publisher: Elsevier  

ISSN Information: 0926-860X

Effects of alkaline-earth metals on the structure, adsorption and catalytic behavior of iron-based Fischer–Tropsch synthesis catalysts

Bình luận của bạn

*

*

*

*

 Captcha

Gửi bình luận nhập lại