Effect of calcium addition on catalytic ethanol steam reforming of Ni/Al₂O₃: I. Catalytic stability, electronic properties and coking mechanism

TY - JOUR

T1 - Effect of calcium addition on catalytic ethanol steam reforming of Ni/Al2O3

T2 - I. Catalytic stability, electronic properties and coking mechanism

AU - Choong, Catherine K.S.

AU - Zhong, Ziyi

AU - Huang, Lin

AU - Wang, Zhan

AU - Ang, Thiam Peng

AU - Borgna, Armando

AU - Lin, Jianyi

AU - Hong, Liang

AU - Chen, Luwei

N1 - Funding Information: We gratefully acknowledge the Agency of Science, Technology and Research (A*STAR), Singapore for its financial support. We also thank Chee Kok Poh for Raman spectroscopy analysis.

PY - 2011/11/4

Y1 - 2011/11/4

N2 - Ca-modified Ni/Al2O3 catalysts with various Ca loadings of 0, 3, 5 and 7 wt% were studied for low temperature catalytic ethanol steam reforming (ESR). Catalyst with 3 wt% of Ca remains stable at 673 K for at least 24 h, while 0 wt%, 5 wt% and 7 wt% Ca modified catalysts deactivate easily. The addition of Ca increases the particle size of active Ni which promotes the formation of un-reactive and encapsulating carbons, undermining the stability of highly loaded (7 wt%) Ca-modified Ni catalyst. XPS valence band shows that the presence of Ca increases the density of Ni 3d band valence electrons which helps in dissociation of methane and deactivates the catalysts, as in the case of nickel catalysts supported on 7 wt% of Ca on Al 2O3. Excellent catalytic performance of 10Ni/3Ca-Al 2O3 is due to the effective coke removal and the amorphous nature of coke deposition. Optimized Ca loading was found to play a critical role in coke removal, through its effect on Ni particle size, valence band of catalyst and steam gasification of coke.

AB - Ca-modified Ni/Al2O3 catalysts with various Ca loadings of 0, 3, 5 and 7 wt% were studied for low temperature catalytic ethanol steam reforming (ESR). Catalyst with 3 wt% of Ca remains stable at 673 K for at least 24 h, while 0 wt%, 5 wt% and 7 wt% Ca modified catalysts deactivate easily. The addition of Ca increases the particle size of active Ni which promotes the formation of un-reactive and encapsulating carbons, undermining the stability of highly loaded (7 wt%) Ca-modified Ni catalyst. XPS valence band shows that the presence of Ca increases the density of Ni 3d band valence electrons which helps in dissociation of methane and deactivates the catalysts, as in the case of nickel catalysts supported on 7 wt% of Ca on Al 2O3. Excellent catalytic performance of 10Ni/3Ca-Al 2O3 is due to the effective coke removal and the amorphous nature of coke deposition. Optimized Ca loading was found to play a critical role in coke removal, through its effect on Ni particle size, valence band of catalyst and steam gasification of coke.

KW - Calcium oxide

KW - Coke mechanism

KW - Ethanol

KW - Nickel catalyst

KW - Stability

KW - Steam reforming

KW - Surface OH groups

KW - Water adsorption

UR - http://www.scopus.com/inward/record.url?scp=80053954925&partnerID=8YFLogxK

U2 - 10.1016/j.apcata.2011.08.037

DO - 10.1016/j.apcata.2011.08.037

M3 - 文章

AN - SCOPUS:80053954925

SN - 0926-860X

VL - 407

SP - 145

EP - 154

JO - Applied Catalysis A: General

JF - Applied Catalysis A: General

IS - 1-2

ER -