Abstract
Silver nanowires have been obtained by polyol reduction of silver nitrate in presence of polyvinyl-pyrrolidone (PVP). The as-synthesized silver nanowires were deposited on α- Al2O3. For comparison silver catalysts were also prepared by wetness impregnation obtaining irregularly shaped silver particles. Epoxidation of styrene to styrene oxide (SO) by molecular oxygen was studied using the silver catalysts. The main products were styrene oxide (SO) and phenylacetaldehyde (Phe). The promotion effect of the Cs on the silver nanowires catalysts was investigated. The Cs loading was in the range of 0–1 wt.% (refereed to silver). Furthermore, the effect of O2:C8H8 molar ratio on the catalytic epoxidation was also investigated. Silver nanowires catalysts showed superior catalytic activity compared to those prepared by impregnation method. Besides, higher O2:C8H8 ratios improved the selectivity to SO. The catalytic activity showed a maximum performance for silver nanowires promoted with 0.25 wt.% of Cs, achieving 94.6% of conversion and total selectivity to desired oxidation products (styrene oxide and phenylacetaldehyde). Moreover, the cesium promotion also contributed to the increase in the selectivity to styrene oxide. Temperature programmed reduction (TPR) and X-ray photoelectron spectroscopy (XPS) were employed to detect the presence of different species of oxygen in the catalysts indicating that subsurface oxygen was beneficial for the epoxidation. The samples were also structurally characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV-visible absorption spectra and selected area electron diffraction pattern (SAED).
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References
Creighton JA, Eadon DG (1991) J Chem Soc Faraday Trans 87:3881
Cao Y, Jin R, Mirkin CA (2001) J Am Chem Soc 123:7961
Nutzenadel C, Zutell A, Chartouni D, Shimid G, and Schalapbach L (2000) Eur Phys J D8 245
Kim F, Kwan S, Akana J, Yang P (2001) J Am Chem Soc 123:4360
Goldstein AN, Echer CM, Alivisatos AP (1992) Science 256:1425
Bohmer MR, Fokkink LGJ, Schonenberger C, Van Der Zande BMI (1997) J Phys Chem B 101:852
Nicewarner SR, Freeman RG, Reiss BD, He L, Pena DJ, Walton ID, Cromer R, Keating CD, Natan MJ (2001) Science 294:137
Esumi K, Matsuhisa K, Torigoe K (1995) Langmuir 11:3285
Murphy CJ, Jana NR (2002) Adv Mater 14:80
Sun YG, Xia YN (2002) Adv Mater 14:833
Yu YY, Chang SS, Lee CL, Wang CRC (1997) J Phys Chem B 101:6661
Chang SS, Shih CW, Chen CD, Lai WC, Wang CRC (1999) Langmuir 15:701
Wang ZL, Mohamed MB, Link S, El-Sayed MA (1999) Surf Sci 440:L809
Sun Y, Xia Y (2002) Science 298:2176
Sun Y, Gates B, Xia Y (2002) Nano Lett 2:165
Williams FJ, Bird DPC, Sykes ECH, Santra AK, Lambert RM (2003) J Phys Chem B 107:3824
Campbell CT (1985) J Phys Chem 89:5789
Sachtler WMH, Backx C, Van Santen RA (1981) Cat Rev Sci Eng 23:127
Scofield JH (1976) J Electr Rel Phen 8:129
XPS International fundamental XPS data tables, www. xpsdata.com
Han HJ, Koo SM (2003) J Sol-Gel Sci Tech 26:467
Meisel D (1998) J Phys Chem B 102:8364
Murphy CJ, Jana NR (2002) Adv Mater 14:80
Cullity BD, Stock SR (2001) Elements of X-ray diffraction, 3rd edn. Prentice-Hall, Upper Saddle River, N.J., pp 402–404
Nagy AJ, Mestl G, Herein D, Weinberg G, Kiltzelmann E, Schlogl R (1999) J Catal 182:417
Nagy AJ, Mestl G (1999) Appl Catal 188:337
Nagy AJ, Mestl G, Schlogl R (1998) J Catal 188:58
Herein D, Nagy A, Schubert H, Weinberg G, Kitzelmann E, Schlogl R (1996) Z Phys Chem 197:67
Nagy AJ, Mestl G, Herein D, Weinberg G, Kiltzelmann E, Schlogl R (1999) J Catal 182:417
Somorjai GA (1994) Introduction to surface chemistry and catalysis. Wiley, New York
Li WX, Stampfl CS, Scheffler M (2003) Phys Rev B 67:045408
Bao X, Muhler M, Scedel-Niedrig T, Schlogl R (1996) Phys Rev B 54:2249
Nagy A, Mestl G, Rule T, Weinberg G, Schogl R (1998) J Catal 179:548
Waterhouse GIN, Bowmaker GA, Metson JB (2003) Appl Catal 214:36
Van Santen RA, Kuipers HPCE (1987) Adv Catal 35:265
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This work was supported by the Ministerio de Ciencia y Tecnologia (Spain) under Projects REN2002-04464-CO2-01 and PETRI 95-0801.OP.
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Chimentao, R.J., Medina, F., Sueiras, J.E. et al. Effects of morphology and cesium promotion over silver nanoparticles catalysts in the styrene epoxidation. J Mater Sci 42, 3307–3314 (2007). https://doi.org/10.1007/s10853-006-0570-1
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DOI: https://doi.org/10.1007/s10853-006-0570-1