Acta Phys. -Chim. Sin. ›› 2013, Vol. 29 ›› Issue (01): 183-190.doi: 10.3866/PKU.WHXB201211021

• CATALYSIS AND SURFACE SCIENCE • Previous Articles     Next Articles

Epoxidation of Propylene over Small-Crystal TS-1 Extrudate in a Fixed-Bed Reactor

ZUO Yi, SONG Wan-Cang, WANG Meng-Li, XU Yong-Hai, WANG Xiang-Sheng, GUO Xin-Wen   

  1. State Key Laboratory of Fine Chemicals, Department of Catalysis Chemistry and Engineering, Faculty of Chemical, Environmental and Biological Science and Technology, Dalian University of Technology, Dalian 116024, Liaoning Province, P. R. China
  • Received:2012-09-03 Revised:2012-11-01 Published:2012-12-14
  • Supported by:

    The project was supported by the New Century Excellent Talent in University, China (NCET-04-0268) and Plan 111 Project of the Ministry of Education of China.

Abstract:

A small-crystal titanium silicalite-1 (TS-1) with a size of 600 nm×400 nm×250 nm was synthesized using a nano-sized TS-1 mother liquor as the seed in a tetrapropyl ammonium bromide (TPABr)-ethylamine hydrothermal system, and was extruded with silica sol. The obtained TS-1 extrudate was characterized by X-ray powder diffraction (XRD), Fourier-transform infrared (FTIR) spectroscopy, ultraviolet-visible (UV-Vis) diffuse reflectance spectroscopy, and nitrogen physisorption. The reaction conditions, including temperature, pressure, molar ratio of propylene/H2O2 (n(C3H6)/n(H2O2)), the weight hourly space velocity (WHSV) of propylene, methanol and H2O2, and the concentration of NH3·H2O, were systematically studied to identify ideal condition propylene epoxidation over small-crystal TS-1 extrudate. The reaction temperature had little effect on the propylene oxide (PO) yield under the conditions examined. The highest PO yield was obtained when the pressure was 2.0 MPa and the n(C3H6)/n(H2O2) was 4. The PO content in the product was maximized when the WHSVs of propylene, methanol and H2O2 was 0.93, 2.5 and 0.25 h-1respectively. A low concentration of NH3·H2O was beneficial for a high PO yield. Under the optimized condition, we compared catalytic performances of TS-1 with different crystal sizes and performed a long-term test over the small-crystal TS-1. The tests indicated that H2O2 conversion and PO selectivity could both reach 95%, even after 1000 h on stream.

Key words: Epoxidation of propylene, TS-1, H2O2, Reaction condition, Characterization, Fixed-bed reactor

MSC2000: 

  • O643