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Erschienen in: Journal of Materials Science 24/2016

23.08.2016 | Original Paper

Preparation, characterization, and activity of SnO2 nanoparticles supported on Al2O3 as a catalyst for the selective reduction of NO with C3H6

verfasst von: Masaaki Haneda, Yusuke Ota, Yasuyuki Doi, Masatomo Hattori

Erschienen in: Journal of Materials Science | Ausgabe 24/2016

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Abstract

SnO2 nanoparticles were prepared using the hydrothermal method. The particle size was gradually increased with increasing the hydrothermal temperature and period. The size of SnO2 nanoparticles was successfully controlled in the range of 2.3–5.9 nm. The deposition of SnO2 nanoparticles on to Al2O3 was made through impregnation process. TEM and XRD measurements revealed that SnO2 nanoparticles are highly dispersed on the surface of Al2O3 without changing the particle size. When SnO2 nanoparticles prepared at 150 °C for 3 h were deposited on to Al2O3 (denoted as SnO2-150-3/Al2O3), a part of SnO2 nanoparticles was suspected to be dispersed inside of the pores of Al2O3. This is probably due to a small size of SnO2 nanoparticles compared with the pore diameter of Al2O3. On the other hand, SnO2 nanoparticles with relatively large size were found to be predominantly present on the outer surface of Al2O3. H2-TPR measurements suggest the presence of SnO2–Al2O3 interaction in SnO2/Al2O3 catalysts. Especially, SnO2-150-3/Al2O3 was considered to include SnO2 nanoparticles interacting more strongly with Al2O3. SnO2/Al2O3 catalysts showed higher catalytic activity for the selective reduction of NO with C3H6 than Al2O3, suggesting that the SnO2/Al2O3 prepared using SnO2 nanoparticles is effective to develop highly active catalyst.

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Literatur
1.
Zurück zum Zitat Lucky SS, Soo KC, Zhang Y (2015) Nanoparticles in photodynamic therapy. Chem Rev 115:1990–2042CrossRef Lucky SS, Soo KC, Zhang Y (2015) Nanoparticles in photodynamic therapy. Chem Rev 115:1990–2042CrossRef
2.
Zurück zum Zitat Irvine DJ, Hanson MC, Rakhra K, Tokatlian T (2015) Synthetic nanoparticles for vaccines and immunotherapy. Chem Rev 115:11109–11146CrossRef Irvine DJ, Hanson MC, Rakhra K, Tokatlian T (2015) Synthetic nanoparticles for vaccines and immunotherapy. Chem Rev 115:11109–11146CrossRef
3.
Zurück zum Zitat Thanh NTK, Maclean N, Mahiddine S (2014) Mechanisms of nucleation and growth of nanoparticles in solution. Chem Rev 114:7610–7630CrossRef Thanh NTK, Maclean N, Mahiddine S (2014) Mechanisms of nucleation and growth of nanoparticles in solution. Chem Rev 114:7610–7630CrossRef
4.
Zurück zum Zitat Duan H, Wang D, Li Y (2015) Green chemistry for nanoparticles synthesis. Chem Soc Rev 44:5778–5792CrossRef Duan H, Wang D, Li Y (2015) Green chemistry for nanoparticles synthesis. Chem Soc Rev 44:5778–5792CrossRef
5.
Zurück zum Zitat Hussain I, Graham S, Wang Z, Tan B, Sherrington DC, Rannard SP, Cooper AI, Brust M (2005) Size-controlled synthesis of near-monodisperse gold nanoparticles in the 1–4 nm range using polymeric stabilizers. J Am Chem Soc 127:16398–16399CrossRef Hussain I, Graham S, Wang Z, Tan B, Sherrington DC, Rannard SP, Cooper AI, Brust M (2005) Size-controlled synthesis of near-monodisperse gold nanoparticles in the 1–4 nm range using polymeric stabilizers. J Am Chem Soc 127:16398–16399CrossRef
6.
Zurück zum Zitat Teranishi T, Miyake M (1998) Size control of palladium nanoparticles and their crystal structures. Chem Mater 10:594–600CrossRef Teranishi T, Miyake M (1998) Size control of palladium nanoparticles and their crystal structures. Chem Mater 10:594–600CrossRef
7.
Zurück zum Zitat Watanabe R, Ishizaki T (2013) Size- and shape-controlled synthesis of colloidal Sn, Te, and Bi nanocrystals. Bull Chem Soc Jpn 86:642–650CrossRef Watanabe R, Ishizaki T (2013) Size- and shape-controlled synthesis of colloidal Sn, Te, and Bi nanocrystals. Bull Chem Soc Jpn 86:642–650CrossRef
8.
Zurück zum Zitat Tian N, Zhou ZY, Sun SG, Ding Y, Wang ZL (2007) Synthesis of tetrahexahedral platinum nanocrystals with high-index facets and high electro-oxidation activity. Science 316:732–735CrossRef Tian N, Zhou ZY, Sun SG, Ding Y, Wang ZL (2007) Synthesis of tetrahexahedral platinum nanocrystals with high-index facets and high electro-oxidation activity. Science 316:732–735CrossRef
9.
Zurück zum Zitat Salavati-Niasari M, Davar F, Mir N (2008) Synthesis and characterization of metallic copper nanoparticles via thermal decomposition. Polyhedron 27:3514–3518CrossRef Salavati-Niasari M, Davar F, Mir N (2008) Synthesis and characterization of metallic copper nanoparticles via thermal decomposition. Polyhedron 27:3514–3518CrossRef
10.
Zurück zum Zitat Panáček A, Kvitek L, Pureck R, Kolář M, Večeřová R, Pizúrová N, Sharma VK, Nevĕčná T, Zbořil R (2006) Silver colloid nanoparticles: synthesis, characterization, and their antibacterial activity. J Phys Chem B 110:16248–16253CrossRef Panáček A, Kvitek L, Pureck R, Kolář M, Večeřová R, Pizúrová N, Sharma VK, Nevĕčná T, Zbořil R (2006) Silver colloid nanoparticles: synthesis, characterization, and their antibacterial activity. J Phys Chem B 110:16248–16253CrossRef
11.
Zurück zum Zitat Zhou HS, Honma I, Komiyama H, Haus JW (1994) Controlled synthesis and quantum-size effect in gold-coated nanoparticles. Phys Rev B 50:12052–12056CrossRef Zhou HS, Honma I, Komiyama H, Haus JW (1994) Controlled synthesis and quantum-size effect in gold-coated nanoparticles. Phys Rev B 50:12052–12056CrossRef
12.
Zurück zum Zitat Imagawa H, Suda A, Yamaura K, Sun S (2011) Monodisperse CeO2 nanoparticles and their oxygen storage and release properties. J Phys Chem C 115:1740–1745CrossRef Imagawa H, Suda A, Yamaura K, Sun S (2011) Monodisperse CeO2 nanoparticles and their oxygen storage and release properties. J Phys Chem C 115:1740–1745CrossRef
13.
Zurück zum Zitat Taniguchi T, Watanabe T, Sakamoto N, Matsushita N, Yoshimura M (2008) Aqueous route to size-controlled and doped organophilic ceria nanocrystals. Cryst Growth Des 8:3725–3730CrossRef Taniguchi T, Watanabe T, Sakamoto N, Matsushita N, Yoshimura M (2008) Aqueous route to size-controlled and doped organophilic ceria nanocrystals. Cryst Growth Des 8:3725–3730CrossRef
14.
Zurück zum Zitat Kobayashi K, Haneda M, Ozawa M (2012) Hydrothermal synthesis of CeO2 nanocrystals using oleate-modified precipitation method. Adv Mater Res 463–464:1501–1505CrossRef Kobayashi K, Haneda M, Ozawa M (2012) Hydrothermal synthesis of CeO2 nanocrystals using oleate-modified precipitation method. Adv Mater Res 463–464:1501–1505CrossRef
15.
Zurück zum Zitat Tanimoto K, Kato H, Hidaka H, Hinokuma S, Ikeue K, Machida M (2013) Nanometric colloidal sols of CeO2-ZrO2 solid solution as catalyst modifiers. I. preparation and structure. Bull Chem Soc Jpn 86:1210–1215CrossRef Tanimoto K, Kato H, Hidaka H, Hinokuma S, Ikeue K, Machida M (2013) Nanometric colloidal sols of CeO2-ZrO2 solid solution as catalyst modifiers. I. preparation and structure. Bull Chem Soc Jpn 86:1210–1215CrossRef
16.
Zurück zum Zitat Chen Z, Pan D, Li Z, Jiao Z, Wu M, Shek C-H, Wu CML, Lai JKL (2014) Recent advances in tin dioxide materials: some developments in thin films, nanowires and nanorods. Chem Rev 114:7442–7486CrossRef Chen Z, Pan D, Li Z, Jiao Z, Wu M, Shek C-H, Wu CML, Lai JKL (2014) Recent advances in tin dioxide materials: some developments in thin films, nanowires and nanorods. Chem Rev 114:7442–7486CrossRef
18.
Zurück zum Zitat Baik NS, Sakai G, Miura N, Yamazoe N (2000) Preparation of stabilized nanosized tin oxide particles by hydrothermal treatment. J Am Ceram Soc 83:2983–2987CrossRef Baik NS, Sakai G, Miura N, Yamazoe N (2000) Preparation of stabilized nanosized tin oxide particles by hydrothermal treatment. J Am Ceram Soc 83:2983–2987CrossRef
19.
Zurück zum Zitat Chiu H-C, Yeh C-S (2007) Hydrothermal synthesis of SnO2 nanoparticles and their gas-sensing of alcohol. J Phys Chem C 111:7256–7259CrossRef Chiu H-C, Yeh C-S (2007) Hydrothermal synthesis of SnO2 nanoparticles and their gas-sensing of alcohol. J Phys Chem C 111:7256–7259CrossRef
20.
Zurück zum Zitat Adnan R, Razana NA, Rahman IA, Farrukh MA (2010) Synthesis and characterization of high surface area tin oxide nanoparticles via the sol-gel method as a catalyst for the hydrogenation of styrene. J Chin Chem Soc 57:222–229CrossRef Adnan R, Razana NA, Rahman IA, Farrukh MA (2010) Synthesis and characterization of high surface area tin oxide nanoparticles via the sol-gel method as a catalyst for the hydrogenation of styrene. J Chin Chem Soc 57:222–229CrossRef
21.
Zurück zum Zitat Moghdam MB, Zebarjad SM, Emampour JS, Youssefi A (2013) A study on the role of ethylene glycol/alcohol ratio on synthesis of nano-size SnO2. Particul Sci Technol 31:66–70CrossRef Moghdam MB, Zebarjad SM, Emampour JS, Youssefi A (2013) A study on the role of ethylene glycol/alcohol ratio on synthesis of nano-size SnO2. Particul Sci Technol 31:66–70CrossRef
22.
Zurück zum Zitat Jiang J, Sun G, Zhou Z, Sun S, Wang Q, Yan S, Li H, Tian J, Guo J, Zhou B, Xin Q (2005) Size-controllable synthesis of monodispersed SnO2 nanoparticles and application in electrocatalysts. J Phys Chem B 109:8774–8779CrossRef Jiang J, Sun G, Zhou Z, Sun S, Wang Q, Yan S, Li H, Tian J, Guo J, Zhou B, Xin Q (2005) Size-controllable synthesis of monodispersed SnO2 nanoparticles and application in electrocatalysts. J Phys Chem B 109:8774–8779CrossRef
23.
Zurück zum Zitat Jitianu A, Altindag Y, Zaharescu M, Wark M (2003) New SnO2 nano-clusters obtained by sol-gel route, structural characterization and their gas sensing applications. J Sol-Gel Sci Technol 26:483–488CrossRef Jitianu A, Altindag Y, Zaharescu M, Wark M (2003) New SnO2 nano-clusters obtained by sol-gel route, structural characterization and their gas sensing applications. J Sol-Gel Sci Technol 26:483–488CrossRef
24.
Zurück zum Zitat Lan F, Wang X, Xu X, Zhang R, Zhang N (2012) Preparation and characterization of SnO2 catalysts for CO and CH4 oxidation. React Kinet Mech Catal 106:113–125CrossRef Lan F, Wang X, Xu X, Zhang R, Zhang N (2012) Preparation and characterization of SnO2 catalysts for CO and CH4 oxidation. React Kinet Mech Catal 106:113–125CrossRef
25.
Zurück zum Zitat Mizuhata M, Umegaki Y, Nakata A, Kumaresan R, Deki S (2009) Room-temperature synthesis of monodispersed SnO2 nanoparticles by liquid phase deposition. Chem Lett 38:974–975CrossRef Mizuhata M, Umegaki Y, Nakata A, Kumaresan R, Deki S (2009) Room-temperature synthesis of monodispersed SnO2 nanoparticles by liquid phase deposition. Chem Lett 38:974–975CrossRef
26.
Zurück zum Zitat Haneda M, Ohzu S, Kintaichi Y, Shimizu K, Shibata J, Yoshida H, Hamada H (2001) Sol-gel prepared Sn-Al2O3 catalysts for the selective reduction of NO with propene. Bull Chem Soc Jpn 74:2075–2081CrossRef Haneda M, Ohzu S, Kintaichi Y, Shimizu K, Shibata J, Yoshida H, Hamada H (2001) Sol-gel prepared Sn-Al2O3 catalysts for the selective reduction of NO with propene. Bull Chem Soc Jpn 74:2075–2081CrossRef
27.
Zurück zum Zitat Tabata M, Hamada H, Suganuma F, Yoshinari T, Tsuchida H, Kintaichi Y, Sasaki M, Ito T (1994) Promotive effect of Sn on the catalytic activity of Al2O3 for the selective reduction of NO by methanol. Catal Lett 25:55–60CrossRef Tabata M, Hamada H, Suganuma F, Yoshinari T, Tsuchida H, Kintaichi Y, Sasaki M, Ito T (1994) Promotive effect of Sn on the catalytic activity of Al2O3 for the selective reduction of NO by methanol. Catal Lett 25:55–60CrossRef
28.
Zurück zum Zitat Kung MC, Park PW, Kim D-W, Kung HH (1999) Lean NOx catalysis over Sn/γ-Al2O3 catalysts. J Catal 181:1–5CrossRef Kung MC, Park PW, Kim D-W, Kung HH (1999) Lean NOx catalysis over Sn/γ-Al2O3 catalysts. J Catal 181:1–5CrossRef
29.
Zurück zum Zitat Park PW, Kung HH, Kim D-W, Kung MC (1999) Characterization of SnO2/Al2O3 lean NO x catalysts. J Catal 184:440–454CrossRef Park PW, Kung HH, Kim D-W, Kung MC (1999) Characterization of SnO2/Al2O3 lean NO x catalysts. J Catal 184:440–454CrossRef
30.
Zurück zum Zitat Liu Z, Li J, Hao J (2010) Selective catalytic reduction of NOx with propene over SnO2/Al2O3 catalyst. Chem Eng J 165:420–425CrossRef Liu Z, Li J, Hao J (2010) Selective catalytic reduction of NOx with propene over SnO2/Al2O3 catalyst. Chem Eng J 165:420–425CrossRef
31.
Zurück zum Zitat Fujihara S, Maeda T, Ohgi H, Hosono E, Imai H, Kim S-H (2004) Hydrothermal routes to prepare nanocrystalline mesoporous SnO2 having high thermal stability. Langmuir 20:6476–6481CrossRef Fujihara S, Maeda T, Ohgi H, Hosono E, Imai H, Kim S-H (2004) Hydrothermal routes to prepare nanocrystalline mesoporous SnO2 having high thermal stability. Langmuir 20:6476–6481CrossRef
32.
Zurück zum Zitat Saikala R, Gupta NM, Kulshreshtha SK (2001) Temperature-programmed reduction and CO oxidation studies over Ce-Sn mixed oxides. Catal Lett 71:69–73CrossRef Saikala R, Gupta NM, Kulshreshtha SK (2001) Temperature-programmed reduction and CO oxidation studies over Ce-Sn mixed oxides. Catal Lett 71:69–73CrossRef
33.
Zurück zum Zitat Lieske H, Völter J (1984) State of tin in Pt-Sn/Al2O3 reforming catalysts investigated by TPR and chemisorption. J Catal 90:96–105CrossRef Lieske H, Völter J (1984) State of tin in Pt-Sn/Al2O3 reforming catalysts investigated by TPR and chemisorption. J Catal 90:96–105CrossRef
34.
Zurück zum Zitat Auroux A, Sprinceana D, Gervasini A (2000) Support effects on de-NO x catalytic properties of supported tin oxides. J Catal 195:140–150CrossRef Auroux A, Sprinceana D, Gervasini A (2000) Support effects on de-NO x catalytic properties of supported tin oxides. J Catal 195:140–150CrossRef
35.
Zurück zum Zitat Fabritchnyl PB, Sudakova NR, Berentsveig VV, Demazeau G, Afanasov MI, Etourneau J (1992) Modifying action of Sn4+ ions located at the surface of a Cr2O3 catalyst investigated by means of Mössbauer spectroscopy. J Mater Sci 2:763–764. doi:10.1039/JM9920200763 Fabritchnyl PB, Sudakova NR, Berentsveig VV, Demazeau G, Afanasov MI, Etourneau J (1992) Modifying action of Sn4+ ions located at the surface of a Cr2O3 catalyst investigated by means of Mössbauer spectroscopy. J Mater Sci 2:763–764. doi:10.​1039/​JM9920200763
36.
Zurück zum Zitat Wang X, Xie Y-C (2001) Total oxidation of CH4 on Sn-Cr composite oxide catalysts. Appl Catal B 35:85–94CrossRef Wang X, Xie Y-C (2001) Total oxidation of CH4 on Sn-Cr composite oxide catalysts. Appl Catal B 35:85–94CrossRef
37.
Zurück zum Zitat Xu X, Zhang R, Zeng X, Han X, Li Y, Liu Y, Wang X (2013) Effect of La, Ce, and Y oxides on SnO2 catalysts for CO and CH4 oxidation. ChemCatChem 5:2025–2036CrossRef Xu X, Zhang R, Zeng X, Han X, Li Y, Liu Y, Wang X (2013) Effect of La, Ce, and Y oxides on SnO2 catalysts for CO and CH4 oxidation. ChemCatChem 5:2025–2036CrossRef
38.
Zurück zum Zitat Xu X, Sun X, Han H, Peng H, Liu W, Peng X, Wang X, Yang X (2015) Improving water tolerance of Co3O4 by SnO2 addition for CO oxidation. Appl Surf Sci 355:1254–1260CrossRef Xu X, Sun X, Han H, Peng H, Liu W, Peng X, Wang X, Yang X (2015) Improving water tolerance of Co3O4 by SnO2 addition for CO oxidation. Appl Surf Sci 355:1254–1260CrossRef
39.
Zurück zum Zitat Burch R (2004) Knowledge and know-how in emission control for mobile applications. Catal Rev 46:271–333CrossRef Burch R (2004) Knowledge and know-how in emission control for mobile applications. Catal Rev 46:271–333CrossRef
40.
Zurück zum Zitat Hamada H (1994) Selective reduction of NO by hydrocarbons and oxygenated hydrocarbons over metal oxide catalysts. Catal Today 22:21–40CrossRef Hamada H (1994) Selective reduction of NO by hydrocarbons and oxygenated hydrocarbons over metal oxide catalysts. Catal Today 22:21–40CrossRef
41.
Zurück zum Zitat Shimizu K, Satsuma A, Hattori T (2000) Metal oxide catalysts for selective reduction of NO x by hydrocarbons: toward molecular basis for catalyst design. Catal Surv Jpn 4:115–123CrossRef Shimizu K, Satsuma A, Hattori T (2000) Metal oxide catalysts for selective reduction of NO x by hydrocarbons: toward molecular basis for catalyst design. Catal Surv Jpn 4:115–123CrossRef
42.
Zurück zum Zitat Kung MC, Kung HH (2004) Selective lean NO x reduction over metal oxides. Top Catal 28:105–110CrossRef Kung MC, Kung HH (2004) Selective lean NO x reduction over metal oxides. Top Catal 28:105–110CrossRef
43.
Zurück zum Zitat Liu Z, Woo SI (2006) Recent advances in catalytic DeNO x science and technology. Catal Rev 48:43–89CrossRef Liu Z, Woo SI (2006) Recent advances in catalytic DeNO x science and technology. Catal Rev 48:43–89CrossRef
44.
Zurück zum Zitat Teraoka Y, Harada T, Iwasaki T, Ikeda T, Kagawa S (1993) Selective reduction of nitrogen monoxide with hydrocarbons over SnO2 catalyst. Chem Lett 22:773–776CrossRef Teraoka Y, Harada T, Iwasaki T, Ikeda T, Kagawa S (1993) Selective reduction of nitrogen monoxide with hydrocarbons over SnO2 catalyst. Chem Lett 22:773–776CrossRef
45.
Zurück zum Zitat Hamada H (1997) Cooperation of catalytic species for the selective reduction of nitrogen monoxide with hydrocarbons. Catal Surv Jpn 1:53–60CrossRef Hamada H (1997) Cooperation of catalytic species for the selective reduction of nitrogen monoxide with hydrocarbons. Catal Surv Jpn 1:53–60CrossRef
46.
Zurück zum Zitat Liu Z, Woo SI, Lee WS (2006) In situ FT-IR studies on the mechanism of selective reduction of NO x by propene over SnO2/Al2O3 catalyst. J Phys Chem B 110:26019–26023CrossRef Liu Z, Woo SI, Lee WS (2006) In situ FT-IR studies on the mechanism of selective reduction of NO x by propene over SnO2/Al2O3 catalyst. J Phys Chem B 110:26019–26023CrossRef
47.
Zurück zum Zitat Li J, Hao J, Fu L, Liu Z, Cui X (2004) The activity and characterization of sol-gel Sn/Al2O3 catalyst for selective catalytic reduction of NO x in the presence of oxygen. Catal Today 90:215–221CrossRef Li J, Hao J, Fu L, Liu Z, Cui X (2004) The activity and characterization of sol-gel Sn/Al2O3 catalyst for selective catalytic reduction of NO x in the presence of oxygen. Catal Today 90:215–221CrossRef
48.
Zurück zum Zitat Liu Z, Hao J, Fu L, Zhu T, Li J, Cui X (2003) Promoting effect of sol-gel method and pretreatment on the activity of SnO2/Al2O3 catalyst for NO reduction by propene. React Kinet Catal Lett 80:45–52CrossRef Liu Z, Hao J, Fu L, Zhu T, Li J, Cui X (2003) Promoting effect of sol-gel method and pretreatment on the activity of SnO2/Al2O3 catalyst for NO reduction by propene. React Kinet Catal Lett 80:45–52CrossRef
Metadaten
Titel
Preparation, characterization, and activity of SnO2 nanoparticles supported on Al2O3 as a catalyst for the selective reduction of NO with C3H6
verfasst von
Masaaki Haneda
Yusuke Ota
Yasuyuki Doi
Masatomo Hattori
Publikationsdatum
23.08.2016
Verlag
Springer US
Erschienen in
Journal of Materials Science / Ausgabe 24/2016
Print ISSN: 0022-2461
Elektronische ISSN: 1573-4803
DOI
https://doi.org/10.1007/s10853-016-0307-8

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