Research output: Contribution to Journal/Magazine › Journal article › peer-review
Research output: Contribution to Journal/Magazine › Journal article › peer-review
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TY - JOUR
T1 - Reducible support effects in the gas phase hydrogenation of p-chloronitrobenzene over gold
AU - Wang, Xiaodong
AU - Perret, Noemie
AU - Delgado, Juan J.
AU - Blanco, Ginesa
AU - Chen, Xiaowei
AU - Olmos, Carol M.
AU - Bernal, Serafin
AU - Keane, Mark A.
PY - 2013
Y1 - 2013
N2 - The use of nonreducible (Al2O3) and reducible (Ce0.62Zr0.38O2, CZ) carriers to support nanoscale Au has been studied in gas phase p-chloronitrobenzene hydrogenation. Reaction over Au/Al2O3 generated p-chloroaniline as the sole product, whereas Au/CZ catalyzed nitro-group reduction and dechlorination to aniline. A parallel/consecutive kinetic model has been applied to quantify selectivity for Au/CZ. Catalyst characterization has included temperature programmed reduction (TPR)/desorption (TPD), XPS, HAADF-STEM, CO adsorption-FTIR, and oxygen storage capacity (OSC) measurements. The incorporation of Au with CZ promoted reduction of the support with the generation of surface hydrogen and oxygen vacancies, where the latter was facilitated at higher reduction temperature (from 393 to 973 K). Strong Au–CZ interactions enhanced Au dispersion with a narrow size distribution (mean = 1.8–1.9 nm) and influenced adsorptive and catalytic properties. Sintering of Au (from 5.7 to 8.8 nm mean) on Al2O3 was observed with increasing reduction temperature (473–673 K). A higher H2 content in the reacting gas elevated hydrogenation (action of supported Au), whereas dechlorination (action of oxygen vacancies) over Au/CZ was favored under H2 lean conditions. The contribution of spillover hydrogen to increase selective hydrogenation rate is demonstrated. A temporal irreversible loss of activity is established and linked to Cl poisoning of oxygen vacancies.
AB - The use of nonreducible (Al2O3) and reducible (Ce0.62Zr0.38O2, CZ) carriers to support nanoscale Au has been studied in gas phase p-chloronitrobenzene hydrogenation. Reaction over Au/Al2O3 generated p-chloroaniline as the sole product, whereas Au/CZ catalyzed nitro-group reduction and dechlorination to aniline. A parallel/consecutive kinetic model has been applied to quantify selectivity for Au/CZ. Catalyst characterization has included temperature programmed reduction (TPR)/desorption (TPD), XPS, HAADF-STEM, CO adsorption-FTIR, and oxygen storage capacity (OSC) measurements. The incorporation of Au with CZ promoted reduction of the support with the generation of surface hydrogen and oxygen vacancies, where the latter was facilitated at higher reduction temperature (from 393 to 973 K). Strong Au–CZ interactions enhanced Au dispersion with a narrow size distribution (mean = 1.8–1.9 nm) and influenced adsorptive and catalytic properties. Sintering of Au (from 5.7 to 8.8 nm mean) on Al2O3 was observed with increasing reduction temperature (473–673 K). A higher H2 content in the reacting gas elevated hydrogenation (action of supported Au), whereas dechlorination (action of oxygen vacancies) over Au/CZ was favored under H2 lean conditions. The contribution of spillover hydrogen to increase selective hydrogenation rate is demonstrated. A temporal irreversible loss of activity is established and linked to Cl poisoning of oxygen vacancies.
U2 - 10.1021/jp3093836
DO - 10.1021/jp3093836
M3 - Journal article
VL - 117
SP - 994
EP - 1005
JO - Journal of Physical Chemistry C
JF - Journal of Physical Chemistry C
SN - 1932-7447
IS - 2
ER -