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Supporting Information
Nickel Catalyst Stabilization via Graphene
Encapsulation for Enhanced Methanation ReactionChao Wang,a, b, 1 Peng Zhai,a, 1 Zhichao Zhang,c Yi Zhou,a Jiakang Zhang,a Hui Zhang,d Zujin Shi,
a,* Ray P.S. Han b and Fuqiang Huang, a, d, * Ding Ma, a,*
a College of Chemistry and Molecular Engineering, b College of Engineering, Peking University,
Beijing 100871, P. R. China
c Beijing University of Chemical Technology, Beijing 100029, P. R. China
d Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050, P. R. China
1 These authors contributed equally to this work.
* Email: [email protected]; [email protected]; [email protected].
Table S1. Surface area, pore volume, average pore diameter of nickel catalysts
Catalyst SBET (m2 g-1) Vpa (cm3/g) Dp
b (nm)
Ni NPs 18.0 0.068 15.1
Ni@G 21.6 0.151 27.9
Ni@G-N 48.0 0.310 25.8
a Total pore volume at 0.99 P/P0.b Average pore diameter calculated according to equation Dp=4Vp/SBET.
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Fig. S1. The schematic diagram of the reaction equipment.
Fig. S2. Thermogravimetric analysis (TGA) of the Ni@G product. The content of Ni in the
Ni@G sample estimated from the thermal analysis is ca. 87.4 wt%. (Note: Ni was oxidized into
NiO). The analysis was taken in air with a heating rate of 10 C min-1.
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Fig. S3. (a) XRD pattern of the Ni@G-N sample. (b) Raman spectrum of the Ni@G-N. (c) TEM
and HRTEM image of the as-prepared Ni@G-N.
Fig. S4. The N2 adsorption/desorption isotherms of nickel catalysts (Ni@G, Ni@G-N, Ni NPs)
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Fig.S5. CO Conversion versus time on stream of the Ni@G, Ni@G-N catalysts at 450 oC （WHSV=12 L.gcat-1.h-1）
Fig. S6. Examination of the effect of (a) external diffusion and (b) internal diffusion on Ni@G. The reaction were conducted at 450 C, 240 L. gcat
-1. h-1.
Fig. S7. TEM and HRTEM images of the as-prepared Ni@G (a) and Ni@G-N (b) after catalytic
reaction at 450 C.
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Fig. S8. The CO temperature-programmed desorption (TPD) profiles of nickel catalysts (Ni@G,
Ni@G-N, Ni NPs).
Fig. S9. (a) CO conversion versus time on stream of the Ni@G, Ni@G-N catalysts with and
without H2 treatment. (b, c) TEM images of the Ni@G (b) and Ni@G-N (c) after H2 treatment.
The insets are the related enlarged HRTEM images.
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Fig. S10. Mass spectrometry pattern of the Ni@G catalyst during the H2 treatment
Mass and heat transfer calculation for methanation on nickel catalysts
Fig. S11. The methanation reaction performance on the nickel catalysts.
Mears criterion for external diffusion
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If −r A
' ρb Rnk c CAb
<0.15, the external mass transfer effects can be neglected.
−r A' ρb Rn
k c CAb=[5.17*10-4 kmol. kgcat
-1. s-1] [173.7 kg. m-3] [1.2*10-4 m] [1] /([0.25 m. s-1]*[0.0112
kmol. m-3]=3.8*10-3 ≤ 0.15
Weisz-Prater criterion for internal diffusion
If C℘=−r A
' ρc R2
De C As<1, the internal mass transfer effects can be neglected.
C℘=−r A
' ρc R2
De C As=[5.17*10-4 kmol. kgcat
-1. s-1] [8.9*103 kg. m-3] [1.2*10-4 m]2 /([6.51*10-5 m2. s-
1]*[0.0112 kmol. m-3]=0.091<1
Mears criterion for heat transfer
|−∆ H r (−r A' ) ρb ℜ
hT b2 Rg
|<0.15
[206.103 kJ. mol-1] [5.17* 10-4 kmol. kgcat-1. s-1] [173.7 kg. m-3] [1.2*10-4 m] [80 kJ. mol-1]/([5.3
kJ. m-2. K-1. s-1]*[723 K]2*[8.314*10-3 kJ. mol-1. K-1]=7.7*10-6<0.15
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