Acta Phys. -Chim. Sin. ›› 2014, Vol. 30 ›› Issue (10): 1932-1940.doi: 10.3866/PKU.WHXB201408051

• CATALYSIS AND SURFACE SCIENCE • Previous Articles     Next Articles

Comparison of FeMn, FeMnNa and FeMnK Catalysts for the Preparation of Light Olefins from Syngas

LI Jiang-Bing1,2, MA Hong-Fang1, ZHANG Hai-Tao1, SUN Qi-Wen3, YING Wei-Yong1, FANG Ding-Ye1   

  1. 1. State Key Laboratory of Chemical Engineering, Engineering Research Center of Large Scale Reactor Engineering and Technology of the Ministry of Education, East China University of Science and Technology, Shanghai 200237, P. R. China;
    2. Key Laboratory for Green Processing of Chemical Engineering of Xinjiang Bingtuan, School of Chemistry and Chemical Engineering, Shihezi University, Shihezi 832003, The Xinjiang Uygur Autonomous Region, P. R. China;
    3. State Key Laboratory of Coal Liquefaction and Coal Chemical Technology, Shanghai 201203, P. R. China
  • Received:2014-06-20 Revised:2014-08-04 Published:2014-09-30
  • Contact: YING Wei-Yong E-mail:wying@ecust.edu.cn
  • Supported by:

    The project was supported by the Major State Basic Research Program of China (2010CB736203) and National High-Tech R&D Program of China (2011AA05A204).

Abstract:

The influence of sodium and potassium promoters on the structure and reaction behavior of an FeMn catalyst toward light olefin synthesis from syngas was investigated by N2 adsorption, X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), H2 temperature-programmed reduction (H2-TPR), CO/CO2 temperature-programmed desorption (CO/CO2-TPD), Mössbauer spectroscopy (MES) and CO+H2 reaction. We found that an increase in manganese improves the dispersion of the active Fe component and light olefin selectivity; however, excessive enrichment with the Mn promoter on the catalyst surface suppresses CO conversion. Potassium and sodium inhibit the reduction of the catalyst in H2 and improve the adsorption of CO2 and CO because of the enhanced surface basicity of the catalysts. After reduction with syngas (nH2/nCO=20) and reaction with syngas (nH2/nCO=3.5), the analysis of the bulk structure was compared with those of the FeMn, FeMnNa, and FeMnK catalysts. The results show that FeCx is found in relatively high levels in the FeMnK catalysts because of the stronger alkalinity and adsorbability of CO. However, Fischer-Tropsch synthesis (FTS) results indicate that sodium and potassium improved the selectivity toward light olefins. The best catalytic performance was achieved by the FeMnNa catalyst. Its CO conversion and light olefins selectivity were 96.2% and 30.5% (molar fraction), respectively.

Key words: Light olefin, Fischer-Tropsch synthesis, FeMn catalyst, Sodium promoter, Potassium promoter

MSC2000: 

  • O643