ESI for “Novel preparation of nanocrystalline magnesia-supported
cesium-promoted ruthenium catalyst with high activity for ammonia
synthesis”
Shan Wu, Jixin Chen, Xingfang Zheng, Haisheng Zeng, Chunming Zeng, Naijia Guan*
Institute of New Catalytic Materials Science, College of Chemistry, Nankai University
and Cooperative Institute of Nankai & Tianjin University, Tianjin 300071, P. R. China
Tel./fax: +86-22-2350-0341; E-mail: guanj@public.tpt.tj.cn
Fig. 1 is XRD patterns of Mg(OH)2, which was obtained in the similar way described in
this communication in the absence of RuCl3·nH2O in the ethylene glycol solution and
without heating procedure. The calculated average crystal size of the Mg(OH)2 was 6.4nm,
suggesting that this method was a convenient and benign way of obtaining fine Mg(OH)2
powder.
2800
+
+
+ Mg(OH)2
+
+
+
+
+
-cat
Activity/¦Ì molh g
-1 -1
2600
+
2400
2200
2000
1800
1600
10
20
30
40
50
60
70
80
30
2Theta/degree
Fig. 1. XRD patterns of Mg(OH)2.
35
40
45
50
55
60
-1
Gas flow rate/ml min
Fig. 2. Dependence of activity for ammonia
synthesis on gas flow rate at 652K.
Fig. 2 illustrates the dependence of activity for ammonia synthesis on gas flow rate at 652K
of reaction temperature. The highest activity was 2660  mol h-1 g-1-cat at the maximum 60
ml min-1 of ammonia synthesis gas flow rate, showing superior catalytic performance to
the catalysts prepared in conventional method.
Fig. 3 is XRD patterns of the Cs-Ru/MgO catalyst before (trace a) and after (trace b)
catalytic reaction. The crystal sizes of magnesia in the catalyst before and after catalytic
reaction were determined to be 7.1 and 24.1 nm, respectively. From trace b it can be seen
1
that the promoter, cesium compound, was present on the catalyst in the amorphous state
after catalytic reaction.
+
Cl2p
- CsNO3
+ MgO
-
+
-
- +
a
-
+
- - + +
b
b
a
10
20
30
40
50
60
70
80
210
2Theta/degree
205
200
195
190
Binding energy/eV
Fig. 3 XRD patterns of Cs-Ru/MgO
Fig. 4 XPS spectra of Cl2p of Cs-Ru/MgO
before (trace a) and after (trace b) (trace a) before catalytic reaction and
catalytic reaction.
sample-P (trace b).
Fig. 4 is the XPS spectra of Cl2p of the Cs-Ru/MgO catalyst (trace a) before catalytic reaction
and sample-P (trace b). The sample-P was prepared by impregnating commercial magnesia
product, as the Ru content of 4.3 wt%, with RuCl3·nH2O aqueous solution for 12h and
dried slowly, then maintained in an oven at 383 K overnight. The sample-P was not treated
with any reduction process. By qualitative comparison, most chlorine in the Cs-Ru/MgO
catalyst is found to have been eliminated efficiently, forming one of the three main factors
insuring the high activity of the catalyst.
In summary, this method reported in the communication was confirmed to be efficient,
facile and economical in dispersing Ru, preparing nanocrystalline magnesia, and removing
chlorine, thus deserving being further investigated.
2