TY - JOUR
T1 - Dendrimer-mediated formation of Cu-CuOx nanoparticles on silica and their physical and catalytic characterization
AU - Larsen, Gustave
AU - Noriega, Sandra
N1 - Funding Information:
Support from the National Science Foundation under grant no. CTS-9733756 is gratefully acknowledged. We thank Dr. X.Z. Li for his help on TEM experiments in Center for Materials Research and Analysis, University of Nebraska-Lincoln.
PY - 2004/12/28
Y1 - 2004/12/28
N2 - Copper-silica catalysts were synthesized by impregnation of sol-gel derived silicas containing entrapped DAB-Am-64 dendrimer as both chelating and pore-templating agent, with methanolic copper nitrate solutions. Basic materials characterization included X-ray diffraction (XRD), transmission electron microscopy (TEM), and nitrogen adsorption. The metallic and monovalent copper contents were determined by N2O decomposition and CO adsorption, respectively. The N2O decomposition reaction and CO adsorption were followed by mass spectrometry (MS) and thermogravimetry in an oscillating balance reactor (OBR). Diffuse reflectance Fourier transform infrared spectroscopy (DRIFTS) was used to monitor the modes of co-adsorption of N 2O and CO as a function of temperature. The N2O + CO temperature-programmed reaction indicates that the copper oxidation state changes under reaction, and as a consequence a transition in reaction regime occurs as temperature increases. Control of the ultimate particle size of Cu species, while heavily influenced by the dendrimer especially at lower Cu:dendrimer ratios, is not exact. Factors such as calcination and reduction temperatures needed to be investigated in order to maximize the impact of dendrimer complexation on the final state of the catalyst.
AB - Copper-silica catalysts were synthesized by impregnation of sol-gel derived silicas containing entrapped DAB-Am-64 dendrimer as both chelating and pore-templating agent, with methanolic copper nitrate solutions. Basic materials characterization included X-ray diffraction (XRD), transmission electron microscopy (TEM), and nitrogen adsorption. The metallic and monovalent copper contents were determined by N2O decomposition and CO adsorption, respectively. The N2O decomposition reaction and CO adsorption were followed by mass spectrometry (MS) and thermogravimetry in an oscillating balance reactor (OBR). Diffuse reflectance Fourier transform infrared spectroscopy (DRIFTS) was used to monitor the modes of co-adsorption of N 2O and CO as a function of temperature. The N2O + CO temperature-programmed reaction indicates that the copper oxidation state changes under reaction, and as a consequence a transition in reaction regime occurs as temperature increases. Control of the ultimate particle size of Cu species, while heavily influenced by the dendrimer especially at lower Cu:dendrimer ratios, is not exact. Factors such as calcination and reduction temperatures needed to be investigated in order to maximize the impact of dendrimer complexation on the final state of the catalyst.
KW - CO adsoiption
KW - Copper dispersion
KW - Dendrimer
KW - NO decomposition
UR - http://www.scopus.com/inward/record.url?scp=8744315409&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=8744315409&partnerID=8YFLogxK
U2 - 10.1016/j.apcata.2004.09.027
DO - 10.1016/j.apcata.2004.09.027
M3 - Article
AN - SCOPUS:8744315409
VL - 278
SP - 73
EP - 81
JO - Applied Catalysis A: General
JF - Applied Catalysis A: General
SN - 0926-860X
IS - 1
ER -