Acta Phys. -Chim. Sin. ›› 2009, Vol. 25 ›› Issue (03): 519-524.doi: 10.3866/PKU.WHXB20090320

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Influence of Citric Acid on Structures and Catalytic Activities of Ru/AC Catalysts for Ammonia Synthesis

 NI Jun, WANG Rong, LIN Jian-Xin, WEI Ke-Mei   

  1. National Research Center of Chemical Fertilizer Catalysts, Fuzhou University, Fuzhou 350002, P. R. China
  • Received:2008-10-06 Revised:2008-11-06 Published:2009-03-02
  • Contact: WEI Ke-Mei E-mail:weikemei@163.com

Abstract:

Citric acid (CA) was used to modify graphitic activated carbon (AC) to improve the ruthenium distribution and the catalytic activity of Ru/AC catalyst. The influence of CA on the texture of AC and Ru/AC, Ru dispersion and catalytic activity were investigated. Transmission electron microscopy (TEM), thermogravimetric analysis (TGA), CO pulse chemisorption and N2 physisorption indicated that minor amounts of citric acid significantly decreased the surface area of AC and increased the content of oxygen-containing functional groups on the surface of AC. This is the result of preferential adsorption of CA in AC micropores which improves the particle distribution of Ru. The optimal loading sequence is CA followed by RuCl3. A suitable content of CA in Ru/AC catalysts has a remarkable influence on the activities of Ru/AC catalysts at low reaction temperature. The greatest increase of activity was 21.4% for the Ru/AC catalysts treated with CA.

Key words: Citric acid, Ruthenium, Dispersion, Activity, Ammonia synthesis

MSC2000: 

  • O643