2
42
P. Chen et al. / Applied Catalysis A: General 433–434 (2012) 236–242
reduction temperature, implying a higher electron density over the
catalyst reduced at higher temperature. This high electron density
over the Ir species is believed to be beneficial to the selectivity of
[11] U.K. Singh, M.A. Vannice, Appl. Catal. A: Gen. 213 (2001) 1–24.
[
[
12] L. Cˇ erven y´ , V. R u˚ zˇ i cˇ ka, Catal. Rev. Sci. Eng. 24 (1982) 503–566.
13] E. Gebauer-Henke, J. Grams, E. Szubiakiewicz, J. Farbotko, R. Touroude, J.
Rynkowski, J. Catal. 250 (2007) 195–208.
0
crotyl alcohol, since it would enhance the interaction between the
[14] A.M. Ruppert, T. Paryjczak, Appl. Catal. A: Gen. 320 (2007) 80–90.
[15] F. Ammari, J. Lamotte, R. Touroude, J. Catal. 221 (2004) 32–42.
charge-enriched Ir0 sites and the charge-deficient carbonyl carbon
[
[
16] K. Liberková, R. Touroude, J. Mol. Catal. A: Chem. 180 (2002) 221–230.
17] M. Abid, V. Paul-Boncour, R. Touroude, Appl. Catal. A: Gen. 297 (2006) 48–59.
(
the bond), and meanwhile, weaken the interaction between the
1
0
Ir sites and the charge-enriched C C bond (). Meanwhile, the
roles of Ir particle size on the selectivity should also be concerned.
According to the adsorption model of crotonaldehyde presented in
[18] R. Zanella, C. Louis, S. Giorgio, R. Touroude, J. Catal. 223 (2004) 328–339.
[19] P. Claus, Appl. Catal. A: Gen. 291 (2005) 222–229.
[
20] J.E. Bailie, H.A. Abdullah, J.A. Anderson, C.H. Rochester, N.V. Richardson, N.
Hodge, J.-G. Zhang, A. Burrows, C.J. Kiely, G.J. Hutchings, Phys. Chem. Chem.
Phys. 3 (2001) 4113–4121.
Scheme 1, the C C bond () and the C O bond ( ) are more likely
1
to be formed simultaneously on the large Ir particles compared to
the small Ir particles, which may lead to a competitive formation of
these bonds, consequently enhancing the selectivity to butanal and
suppressing the selectivity to the desired crotyl alcohol, as shown
in Table 2.
[21] B. Campo, M. Volpe, S. Ivanova, R. Touroude, J. Catal. 242 (2006) 162–171.
[
[
[
22] J.E. Bailie, G.J. Hutchings, Chem. Commun. (1999) 2151–2152.
23] H. Rojas, G. Borda, J. Murcia, P. Reyes, N. Rojas, Dyna 157 (2009) 173–180.
24] H. Rojas, J. Murcia, G. Borda, P. Reyes, N. Rojas, Dyna 159 (2009) 125–134.
[25] M. Abid, R. Touroude, D.Y. Murzin, in: D.G. Morrell (Ed.), Chemical Indus-
tries (Catalysis of Organic Reactions), Marcel Dekker Inc., New York, 2003, pp.
577–585.
[
26] P. Reyes, H. Rojas, G. Pecchi, J.L.G. Fierro, J. Mol. Catal. A: Chem. 179 (2002)
293–299.
4
. Conclusions
[
[
[
27] P. Reyes, H. Rojas, J.L.G. Fierro, J. Mol. Catal. A: Chem. 203 (2003) 203–211.
28] P. Reyes, H. Rojas, J.L.G. Fierro, Appl. Catal. A: Gen. 248 (2003) 59–65.
29] H. Rojas, G. Borda, P. Reyes, J.J. Martínez, J. Valencia, J.L.G. Fierro, Catal. Today
133–135 (2008) 699–705.
30] P. Reyes, M.C. Aguirre, I. Melián-Cabrera, M. López Granados, J.L.G. Fierro, J.
Catal. 208 (2002) 229–237.
In this work, the effect of reduction temperature on the reactiv-
ities and selectivities of the Ir/TiO2 catalysts are studied. Catalyst
deactivation is observed in all the catalysts, due to the strong
adsorption of crotonaldehyde on the catalyst surface and decar-
bonylation reaction. However, high selectivity to crotyl alcohol
could be obtained by the reduction of the uncalcined IrClx/TiO2
catalysts. Both activity and selectivity depend on the electronic
properties of the Ir species and the surface Lewis acid in the cat-
alyst. The catalyst reduced at low temperature (100 C) contains
large content of Ir (a high Ir /Ir ratio) and Cl species, which
results in large amount of strong surface Lewis acid sites and thus
[
[
31] C.G. Raab, J.A. Lercher, J. Mol. Catal. 75 (1992) 71–79.
[32] J.M. Bonnier, J.P. Damon, J. Masson, Appl. Catal. 42 (1988) 285–297.
[
[
33] T.B.L.W. Marinelli, S. Nabuurs, V. Ponec, J. Catal. 151 (1995) 431–438.
34] A. Sepúlveda-Escribano, F. Coloma, F. Rodríguez-Reinoso, J. Catal. 178 (1998)
649–657.
[35] B.A. Riguetto, C.E.C. Rodrigues, M.A. Morales, E. Baggio-Saitovitch, L. Gengem-
bre, E. Payen, C.M.P. Marques, J.M.C. Bueno, Appl. Catal. A: Gen. 318 (2007)
70–78.
◦
ı+
ı+
0
−
[
36] M. Englisch, A. Jentys, J.A. Lercher, J. Catal. 166 (1997) 25–35.
[37] P. Reyes, D. Salinas, C. Campos, M. Oportus, J. Murcia, H. Rojas, G. Borda, J.L.G.
Fierro, Quim. Nova 33 (2010) 777–780.
[38] X. Zhang, W. Chu, X. Wang, W. Yang, S. Sheng, T. Zhang, Chin. J. Catal. 27 (2006)
suppresses the activity and selectivity. Meanwhile, the catalyst
reduced at 300 C (Ir/TiO -300) has the highest activity and selec-
tivity after 500 min reaction. It seems that the enhanced activity
◦
2
863–867.
[
39] F. Ammari, C. Milone, R. Touroude, J. Catal. 235 (2005) 1–9.
and selectivity obtained on the Ir/TiO -300 catalyst are due to the
moderate interaction between the C O bond and the Ir species, and
weakened surface Lewis acid sites.
[40] D. Briggs, M.P. Seah (Eds.), Practical Surface Analysis: Auger and X-ray Photo-
electron Spectroscopy, 2nd ed., Wiley, Chichester, 1990.
2
[
[
[
[
41] K. Tanaka, K.L. Watters, R.F. Howe, J. Catal. 75 (1982) 23–38.
42] F. Solymosi, J. Raskó, J. Catal. 62 (1980) 253–263.
43] A. Bourane, M. Nawdali, D. Bianchi, J. Phys. Chem. B 106 (2002) 2665–2671.
44] Y.M. López-De Jesús, A. Vicente, G. Lafaye, P. Marécot, C.T. Williams, J. Phys.
Chem. C 112 (2008) 13837–13845.
Acknowledgments
[
45] C.R. Guerra, J.H. Schulman, Surf. Sci. 7 (1967) 229–249.
This work was supported by the National Science Foundation of
China (Grant no. 21173194) and the Natural Science Foundation of
Zhejiang Provincial of China (Grant no. Y4100300).
[46] A. Erd o˝ helyi, K. Fodor, G. Suru, Appl. Catal. A: Gen. 139 (1996) 131–147.
[
47] K. Liu, A.Q. Wang, W.S. Zhang, J.H. Wang, Y.Q. Huang, J.Y. Shen, T. Zhang, J. Phys.
Chem. C 114 (2010) 8533–8541.
[48] F. Solymosi, É. Novák, A. Molnár, J. Phys. Chem. 94 (1990) 7250–7255.
[49] E. Iojoiu, P. Gélin, H. Praliaud, M. Primet, Appl. Catal. A: Gen. 263 (2004) 39–48.
[50] P. Gelin, G. Coudurier, Y.B. Taarit, C. Naccache, J. Catal. 70 (1981) 32–40.
[51] A. Dandekar, M.A. Vannice, J. Catal. 183 (1999) 344–354.
[52] F. Delbeq, P. Sautet, J. Catal. 152 (1995) 217–236.
References
[
[
1] P. Gallezot, D. Richard, Catal. Rev. Sci. Eng. 40 (1998) 81–126.
2] P. Mäki-Arvela, J. Hájek, T. Salmi, D.Yu. Murzin, Appl. Catal. A: Gen. 292 (2005)
[53] X.X. Wang, H.Y. Zheng, X.J. Liu, G.Q. Xie, J.Q. Lu, L.Y. Jin, M.F. Luo, Appl. Catal. A:
Gen. 388 (2010) 134–140.
[54] K.V. Narayana, A. Benhmid, J. Radnik, M.-M. Pohl, U. Bentrup, A. Martin, J. Catal.
246 (2007) 399–412.
[55] A. Huidobro, A. Sepúlveda-Escribano, F. Rodríguez-Reinoso, J. Catal. 212 (2002)
1
–49.
[
[
3] M.E. Grass, R.M. Rioux, G.A. Somorjai, Catal. Lett. 128 (2009) 1–8.
4] M. Englisch, V.S. Ranade, J.A. Lercher, Appl. Catal. A: Gen. 163 (1997)
1
11–122.
94–103.
[
[
[
[
[
5] P. Claus, Top. Catal. 5 (1998) 51–62.
[56] A.B. Merlo, G.F. Santori, J. Sambeth, G.J. Siri, M.L. Casella, O.A. Ferretti, Catal.
Commun. 7 (2006) 204–208.
[57] P. Reyes, M.C. Aguirre, G. Pecchi, J.L.G. Fierro, J. Mol. Catal. A: Chem. 164 (2000)
6] M.A. Vannice, B. Sen, J. Catal. 115 (1989) 65–78.
7] M.A. Vannice, J. Mol. Catal. 59 (1990) 165–177.
8] J. Jenck, J.E. Germain, J. Catal. 65 (1980) 133–140.
9] P. Kluson, L. Cerveny, Appl. Catal. A: Gen. 128 (1995) 13–31.
245–251.
[58] M. Consonni, D. Jokic, D.Yu. Murzin, R. Touroude, J. Catal. 188 (1999)
165–175.
[10] V. Ponec, Appl. Catal. A: Gen. 149 (1997) 27–48.