Alumina supported Au-Ni: Surface synergism in the gas phase hydrogenation of nitro-compounds

Fernando Cardenas-Lizana, Santiago Gomez Quero, Gary Jacobs, Yaying Ji, Burtron H. Davis, Lioubov Kiwi-Minsker, Mark A. Keane

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Abstract

The catalytic gas phase hydrogenation of 1,3-dinitrobenzene over Au/Al2O3 delivered exclusive reduction of a single -NO2 substituent to generate 1,3-nitroaniline (E-a = 131 kJ mol(-1)), reaction over Ni/Al2O3 resulted in full hydrogenation to 1,3-phenylenediamine (E-a = 38 kJ mo1(-1)), whereas both products were isolated over Au-Ni/Al2O3. In the hydrogenation of 1,3,5-trinitrobenzene, Au/Al2O3 promoted preferential partial hydrogenation (3,5-dinitroaniline), Ni/Al2O3 generated 1,3,5-triaminobenzene as the predominant product, while Au-Ni/Al2O3 exhibited an intermediate catalytic response. The catalysts have been characterized in terms of temperature programmed reduction (TPR), H-2 chemisorption, powder XRD, high-resolution TEM, XPS, and XANES/EXAFS measurements. Post-TPR, there was evidence of a metal particle redispersion resulting from the introduction of Au to Ni/Al2O3 where HRTEM-EDX mapping has established close proximity of Au and Ni on Au-Ni/Al2O3 with electron transfer from Ni to Au (from XPS analysis). Hydrogen chemisorption on Au-Ni/Al2O3 was 3 times lower than that recorded for Ni/Al2O3, suggesting Au-Ni interaction that inhibits H-2 uptake. Simulation of the XANES/EXAFS response provided a better fit when incorporating Au-Ni interaction. The results demonstrate control of selectivity in poly nitroarene hydrogenation through the use of mono- (Au and Ni) and bi- (Au-Ni) metallic catalysts, where catalytic response is governed by surface composition.

Original languageEnglish
Pages (from-to)11166-11180
Number of pages15
JournalJournal of Physical Chemistry C
Volume116
Issue number20
DOIs
Publication statusPublished - 24 May 2012

Cite this

Cardenas-Lizana, F., Gomez Quero, S., Jacobs, G., Ji, Y., Davis, B. H., Kiwi-Minsker, L., & Keane, M. A. (2012). Alumina supported Au-Ni: Surface synergism in the gas phase hydrogenation of nitro-compounds. Journal of Physical Chemistry C, 116(20), 11166-11180. https://doi.org/10.1021/jp3025528