Ammonia synthesis on graphitic-nanofilament supported Ru catalysts

被引：40
作者：
Li, ZL [1 ]
Liang, CH [1 ]
Feng, ZC [1 ]
Feng, ZC [1 ]
Ying, PL [1 ]
Wang, DZ [1 ]
Li, C [1 ]
机构：
[1] Chinese Acad Sci, Dalian Inst Chem Phys, State Key Lab Catalysis, Dalian 116023, Peoples R China
来源：
JOURNAL OF MOLECULAR CATALYSIS A-CHEMICAL | 2004年 / 211卷 / 1-2期
关键词：
ammonia synthesis; graphitic-nanofilaments; Ru; promoter; kinetics;
D O I：
10.1016/j.molcata.2003.09.028
中图分类号：
O64 [物理化学（理论化学）、化学物理学];
学科分类号：
070304 ; 081704 ;
摘要：
Graphitic-nanofilaments (GNFs) supported ruthenium catalysts were prepared and characterized by NZ physisorption, X-ray diffraction (XRD), transmission electron microscope (TEM) and temperature programmed reduction-mass spectroscopy (TPR-MS) and used for ammonia synthesis in a fixed bed microreactor. The TEMs of the Ru/GNFs and Ru-Ba/GNFs catalysts indicate that the Ru particles are in the range of 2-4 nm, which is the optimum size of Ru particles for the maximum number of B5 type sites. The activity of Ru-Ba/GNFs catalysts is higher than that of Ru-Ba/AC by about 25%. The methanation reaction on the Ru/GNFs catalyst is remarkably inhibited compared with a Ru/AC catalyst. High graphitization of GNFs is likely to be the reason for the high resistance to the methanation reaction. The power rate law for ammonia synthesis on Ru-Ba/GNFs catalysts can be expressed by r = Kp(NH3)(-0.4) P-N2(0.8) P-H2(-0.7), indicating that H-2 is an inhibitor for N-2 activation on the catalyst. Catalysts with the promoters Ba, K and Cs show large differences in activity for ammonia synthesis. The catalyst promoted with Ba (Ba/Ru = 0.2 molar ratio) was found to be the most active, whereas that with a K promoter was the least active. (C) 2003 Elsevier B.V. All rights reserved.
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页码：103 / 109
页数：7
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