TY - JOUR
T1 - Nanosized Ru on high-surface-area superbasic ZrO2-KOH for efficient generation of hydrogen via ammonia decomposition
AU - Yin, Shuang Feng
AU - Xu, Bo Qing
AU - Wang, Shui Ju
AU - Au, Chak Tong
N1 - Funding Information:
Financial supports from RGC, Hong Kong Special Administration Region, China (Grant: 2037/00P at HKBU), and NSF, China (Grant: 20125310 at Tsinghua University) are gratefully acknowledged.
PY - 2006/2/24
Y1 - 2006/2/24
N2 - Amorphous superbasic ZrO2-KOH of high-surface-area was prepared by reflux-digestion of ZrO(OH)2 gel in aqueous KOH (0.5 M), followed by calcination at 873 K. Incipient wetness impregnation of the high-surface-area superbasic ZrO2-KOH with Ru acetylacetonate [Ru(acac)3] and RuCl3 (dissolved in ethanol), respectively, leads to nanosized Ru (2-7 nm) catalysts. We found that the Ru catalyst performs better when the Cl-free Ru precursor is adopted. Due to the high surface area and superbasicity of the support material, the Cl-free Ru/ZrO2-KOH catalyst is highly effective for the generation of COx-free hydrogen from NH3 decomposition. The high dispersion of Ru is related to the high surface area of ZrO2 and to the presence of K+. We deduce that the presence of Cl has direct as well as indirect (by weakening the promotional effect of KOH) effects on the electronic state of Ru nanoparticles. The apparent activation energy of ammonia decomposition on Cl-free Ru supported on the superbasic ZrO2-KOH is higher than that on conventional ZrO 2. N2-TPD results disclosed that the superbasicity of the support material favors the combinative desorption of surface N atoms, a step generally regarded as the rate-determining in catalytic cycle of ammonia decomposition.
AB - Amorphous superbasic ZrO2-KOH of high-surface-area was prepared by reflux-digestion of ZrO(OH)2 gel in aqueous KOH (0.5 M), followed by calcination at 873 K. Incipient wetness impregnation of the high-surface-area superbasic ZrO2-KOH with Ru acetylacetonate [Ru(acac)3] and RuCl3 (dissolved in ethanol), respectively, leads to nanosized Ru (2-7 nm) catalysts. We found that the Ru catalyst performs better when the Cl-free Ru precursor is adopted. Due to the high surface area and superbasicity of the support material, the Cl-free Ru/ZrO2-KOH catalyst is highly effective for the generation of COx-free hydrogen from NH3 decomposition. The high dispersion of Ru is related to the high surface area of ZrO2 and to the presence of K+. We deduce that the presence of Cl has direct as well as indirect (by weakening the promotional effect of KOH) effects on the electronic state of Ru nanoparticles. The apparent activation energy of ammonia decomposition on Cl-free Ru supported on the superbasic ZrO2-KOH is higher than that on conventional ZrO 2. N2-TPD results disclosed that the superbasicity of the support material favors the combinative desorption of surface N atoms, a step generally regarded as the rate-determining in catalytic cycle of ammonia decomposition.
KW - Ammonia decomposition
KW - Hydrogen manufacture
KW - Nanosized ruthenium catalyst
KW - Promoter in catalysis
KW - Solid superbase
KW - Superbasic zirconia
UR - http://www.scopus.com/inward/record.url?scp=32144458434&partnerID=8YFLogxK
U2 - 10.1016/j.apcata.2005.12.005
DO - 10.1016/j.apcata.2005.12.005
M3 - Journal article
AN - SCOPUS:32144458434
SN - 0926-860X
VL - 301
SP - 202
EP - 210
JO - Applied Catalysis A: General
JF - Applied Catalysis A: General
IS - 2
ER -