SCI和EI收录∣中国化工学会会刊

Chin.J.Chem.Eng. ›› 2017, Vol. 25 ›› Issue (12): 1771-1776.DOI: 10.1016/j.cjche.2017.04.004

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Pt-H2SO4/Zr-montmorillonite: An efficient catalyst for the polymerization of octamethylcy-clotetrasiloxane, polymethylhydrosiloxane and hexamethyldisiloxane to low-hydro silicone oil

Yuedong Zhou, Fengfu Li, Junwei Liu, Zhi Yun, Xia Gui   

  1. College of Chemistry and Chemical Engineering, Nanjing Tech University, Nanjing 210009, China
  • Received:2016-12-23 Revised:2017-04-05 Online:2018-01-18 Published:2017-12-28
  • Contact: Zhi Yun,E-mail address:zyun9999@163.com.
  • Supported by:

    Supported by the Priority Academic Program Development of Jiangsu Higher Education Institutions (PAPD).

Pt-H2SO4/Zr-montmorillonite: An efficient catalyst for the polymerization of octamethylcy-clotetrasiloxane, polymethylhydrosiloxane and hexamethyldisiloxane to low-hydro silicone oil

Yuedong Zhou, Fengfu Li, Junwei Liu, Zhi Yun, Xia Gui   

  1. College of Chemistry and Chemical Engineering, Nanjing Tech University, Nanjing 210009, China
  • 通讯作者: Zhi Yun,E-mail address:zyun9999@163.com.
  • 基金资助:

    Supported by the Priority Academic Program Development of Jiangsu Higher Education Institutions (PAPD).

Abstract: The liquid phase ring-opening of octamethylcy-clotetrasiloxane (D4) was investigated over Pt-H2SO4/Zrmontmorillonite catalyst. Montmorillonite (Mt), Zr-Mt, H2SO4/Mt, H2SO4/Zr-Mt and Pt-H2SO4/Zr-Mt were also detected for evaluation. The catalysts were characterized by X-ray fluorescence, X-ray diffraction, nitrogen adsorption-desorption, NH3-TPD and pyridine-FTIR measurements. In comparison to activate clay which is used in the industry of catalyst, Zr-Mt catalyst displayed stronger acidity and more excellent catalytic activity in the polymerization of D4, polymethylhydrosiloxane (D4H) and hexamethyldisiloxane (MM) to low-hydro silicone oil. Relative to Zr-Mt, the acidity of H2SO4/Zr-Mt was noticeably improved and the catalyst exhibited a higher capability of ring-opening of D4 conversion and yield of low-hydro silicone oil. To enhance the stability of H2SO4/Zr-Mt catalyst, a small amount of metals (Pt) was doped. The nitrogen adsorption-desorption results indicated that pore textural parameters of the Pt-H2SO4/Zr-Mt had not changed with larger specific surface area. Compared with H2SO4/Zr-Mt, the total acidity of Pt-H2SO4-Zr/Mt catalyst retained, but the content of the Brønsted acid increased and the content of the Lewis acid decreased. The Pt-H2SO4-Zr/Mt catalyst displayed higher catalyst reproducibility. After 40 h reaction of polymerization, the yield of low-hydro silicone oil decreased from 93% to 42% over H2SO4/Zr-Mt catalyst, while the yield of low-hydro silicone oil reduced from 93% to 78% over Pt-H2SO4/Zr-Mt catalyst. A sharp decrease in catalytic activity after 35 h of Pt-H2SO4/Zr-Mt catalyst was detected. Furthermore, Pt-H2SO4/Zr-Mt was completely regenerated under appropriate condition and appeared good repeatability in the D4, D4H and MM to low-hydro silicone oil.

Key words: Pt-H2SO4/Zr-montmorillonite, Low-hydro silicone oil, Catalyst, Stability, Regeneration

摘要: The liquid phase ring-opening of octamethylcy-clotetrasiloxane (D4) was investigated over Pt-H2SO4/Zrmontmorillonite catalyst. Montmorillonite (Mt), Zr-Mt, H2SO4/Mt, H2SO4/Zr-Mt and Pt-H2SO4/Zr-Mt were also detected for evaluation. The catalysts were characterized by X-ray fluorescence, X-ray diffraction, nitrogen adsorption-desorption, NH3-TPD and pyridine-FTIR measurements. In comparison to activate clay which is used in the industry of catalyst, Zr-Mt catalyst displayed stronger acidity and more excellent catalytic activity in the polymerization of D4, polymethylhydrosiloxane (D4H) and hexamethyldisiloxane (MM) to low-hydro silicone oil. Relative to Zr-Mt, the acidity of H2SO4/Zr-Mt was noticeably improved and the catalyst exhibited a higher capability of ring-opening of D4 conversion and yield of low-hydro silicone oil. To enhance the stability of H2SO4/Zr-Mt catalyst, a small amount of metals (Pt) was doped. The nitrogen adsorption-desorption results indicated that pore textural parameters of the Pt-H2SO4/Zr-Mt had not changed with larger specific surface area. Compared with H2SO4/Zr-Mt, the total acidity of Pt-H2SO4-Zr/Mt catalyst retained, but the content of the Brønsted acid increased and the content of the Lewis acid decreased. The Pt-H2SO4-Zr/Mt catalyst displayed higher catalyst reproducibility. After 40 h reaction of polymerization, the yield of low-hydro silicone oil decreased from 93% to 42% over H2SO4/Zr-Mt catalyst, while the yield of low-hydro silicone oil reduced from 93% to 78% over Pt-H2SO4/Zr-Mt catalyst. A sharp decrease in catalytic activity after 35 h of Pt-H2SO4/Zr-Mt catalyst was detected. Furthermore, Pt-H2SO4/Zr-Mt was completely regenerated under appropriate condition and appeared good repeatability in the D4, D4H and MM to low-hydro silicone oil.

关键词: Pt-H2SO4/Zr-montmorillonite, Low-hydro silicone oil, Catalyst, Stability, Regeneration