Acta Phys. -Chim. Sin. ›› 2015, Vol. 31 ›› Issue (5): 965-972.doi: 10.3866/PKU.WHXB201503024

• CATALYSIS AND SURFACE SCIENCE • Previous Articles     Next Articles

Regulation of Pore Structure and Acidity of a ZSM-5 Catalyst for Dehydration of Glycerol to Acrolein

PAN Wen-Ya1, HUANG Liang1, QIN Feng1, ZHUANG Yan2, LI Xue-Mei2, MA Jian-Xue2, SHEN Wei1, XU Hua-Long1   

  1. 1 Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials, Laboratory of Advanced Materials, Department of Chemistry, Fudan University, Shanghai 200433, P. R. China;
    2 Shanghai Huayi Acrylic Acid Ltd. Co., Shanghai 200137, P. R. China
  • Received:2014-12-09 Revised:2015-02-11 Published:2015-05-08
  • Contact: SHEN Wei, XU Hua-Long E-mail:wshen@fudan.edu.cn;shuhl@fudan.edu.cn
  • Supported by:

    The project was supported by the Science and Technology Commission of Shanghai Municipality for International Collaboration Project, China (14120700700) and Funding of Key Laboratory, China (11JC1400400).

Abstract:

Pore structure and acidity of ZSM-5 catalysts were successfully regulated by alkali treatment. ZSM- 5 was etched in 0.2 mol·L- 1 NaOH solution at 65 and 85 ℃. Micro-mesoporous ZSM-5 catalysts were successfully prepared with a high density of acidic sites. The activity and stability were significantly enhanced with alkali-treated ZSM-5, giving a conversion of glycerol above 95%, with selectivity for acrolein of 78% after 10 h compared with a ZSM-5-at85 (alkali-treated at 85 ℃) catalyst. Characterization of N2 adsorption and desorption isotherms, X-ray diffraction (XRD), 27Al mass atomic spectroscopy-nuclear magnetic resonance (27Al MAS-NMR), and transmission electron microscopy (TEM) were performed to interpret the morphology and surface properties. The results reveal that the Si in the framework of ZSM-5 was leached out by alkali treatment, and many mesopores were formed on the ZSM-5 surface. However, the MFI topology did not change and Al was mainly integrated within the framework. X-ray photoelectron spectroscopy (XPS), X-ray fluorescence (XRF), and NH3-temperature-programed desorption (NH3-TPD) experiments demonstrated that the molar ratio of Si/ Al on the external surface was lower than that in the framework, indicating that more Si on the external surface of ZSM-5 was leached by alkali treatment, while the acidic density increased because of the lower molar ratio of Si/Al near newly formed mesopores. ZSM-5 catalysts with mesopores and higher acidic density enhance reactant diffusion and coking tolerance, which improves the activity and stability during glycerol dehydration.

Key words: Micro-mesoporous ZSM-5, Surface acidity, Alkali treatment, Dehydration of glycerol, Acrolein

MSC2000: 

  • O643