Transcript A brief introduction about CO2 reforming of methane

Hongyan Ma
2013.05.10
1.Background
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Decreasing in coal and oil reserves
A large number of consumption of natural gas
Rich reserves in shale gas and coaled methane
And the support of policies
• Research about the application of methane
Kazuhiro Takanabe, Journal of the Japan Petroleum Institute, 2012,55(1), 1-12
advantages
• Transform natural gas and CO2 into valuable syngas
• Give syngas with a lower ratio of H2/CO of
approximately 1:1
• Make full use of carbon dioxide in low-grade natural
gas resource
Mun-sing F. Ahmad Z.A.,ChemCatChem.,2009,1,192-208
2.Reaction condition
Main reaction
Carbon
deposition
other reaction
(RWGS)
T=640 ℃
T=550 ℃
T=700 ℃
T=820 ℃
Influence the ratio of H2/CO
• The reaction proceeds at temperatures in excess of
913 K (640℃).
• At temperatures in excess of 1093K(820 ℃), the
RWGS and Boudouard reactions will not take place.
• Formation of carbon most likely takes place within
the temperature range 830 K–973, from both the
Boudouard reaction and methane decomposition.
Mun-sing F. Ahmad Z.A.,ChemCatChem.,2009,1,192-208
Conclusion about conditions
• The temperature is important for distribution of
products. Finally chose the range of 700-850 ℃.
Y. Sun. T. Ritchie,Journal of Natural Gas Chemistry ,2011,20,568–576
Y.H. Li, Y.Q.Wang, International journal of hydrogen energy,2008,33,2507-2514
• Pressure : the main reaction is not favorable in
higher pressure, so chose ambient pressure in
experiment in the laboratory .
• CH4/CO2: Although the excess CO2 is helpful for
the conversion of CH4 and resistance for carbon
deposition, a lots of energy will need to recycle the
CO2. So now chose the stoichiometric ratio, namely
1:1.
3.The reaction process
metal active surface(M)
prompter (P)
acidic support
basic support(S)
Mun-sing F. Ahmad Z.A.,ChemCatChem.,2009,1,192-208
Anatta W.B.,S.H.Song.Catal Surv Asia,2012,16,183-197
4.The main challenges
Deactivation
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Poisoning
Carbon deposition
Sintering
Solid-state transformation
Metal oxidation
Pio F., Luca L.,Catalysis Today,1999,52,165-181
Anatta W.B.,S.H.Song.Catal Surv Asia,2012,16,183-197
Carbon deposition and sintering
• Effective method
• (1) metal: size,morphology,structure
The critical size of Ni particles to inhibit coke deposition was
suggested to be about 10nm.
The surface defects can facilitate carbon formation, like steps
and kinks.
Beatriz Fidalgo,Chin.J.Catal.,2011,32,207–216
Kazuhiro Takanabe, Journal of the Japan Petroleum Institute, 2012,55(1), 1-12
• (2)promoter:
enhance the adsorption of CO2 ,enhance the surface reaction,
or decrease the rate and degree of methane activation and
dissociation
• (3)support:
well-defined structure like ABO3 or spinels,and form strong
interaction with active metal.
• (4) others:
form solid solutions or alloy with Ni , Co, Fe, Mg，Mn metal
.
Chang-jun Liu,ChemCatChem,2011, 3, 529 – 541
4, the practical method
• Form some fine particles in reducing strong Ni-x bond,
like Ni-Mg alloy and NiAl2O4.
• Form strong interaction in reduction to fixed metal
practicles, like Pt-Zr+ in Pt/ZrO2
• Disperse active site
(1)using S or B to cover part of site.
(2) special structure like spinel
(3)some inactive species cover some of site formed in reduction.
Like VOx in V2O5 and TiOx in TiO2, MnOx in MnO2.
(4) add some promoter to disperse sites
• Control the size with special structure-encapsulation
Y. H.Hu, E.Ruckenstein ,Adv. Catal. 2004,48,297 – 345
Thank you