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Catalysis Science & Technology
Page 7 of 9
DOI: 10.1039/C7CY01929G
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(Y(H2)), indicating that an acidic condition is appropriate for distinctive photocatalytic activity for the largest production of
ring hydrogenation of BA. On the other hand, H2 evolution was CCA, and apparent quantum efficiency reached 16% at 360
less affected by pH of the suspension. To understand the effect nm. A large amount of OA molecules was adsorbed on Rh-TiO2
of pH on Y(CCA), adsorption experiments were carried out in water, contributing to efficient hole scavenging under light
under various pH conditions (Figure 7(b)). The amount of OA irradiation, and the reaction rate for CCA formation was mainly
adsorbed gradually decreased with increase in pH in an acidic determined by the amount of BA adsorbed. Ring
condition; however, the amount was still large in the basic hydrogenation of BA to CCA under the present conditions
condition. The amount of BA adsorbed was much smaller than consisted of two processes: 1) photocatalytic production of
that of OA as shown in Figure 6, and the amount of BA AHS and 2) thermocatalytic hydrogenation of BA over Rh
adsorbed decreased with increase in pH of the suspension. We particles.
noticed that the behavior of BA adsorption against pH was
similar to that of Y(CCA), and a relatively clear correlation was
Acknowledgements
observed between BA adsorption and Y(CCA), especially in
acidic conditions (Figure 7(c)). This plot indicates that the
reaction rate of BA hydrogenation was decided by the
adsorption of BA, at least in an acidic condition.
This work was partly supported by JSPS KAKENHI Grant
Numbers 17H03462, 15J11412, 16K18292 and 17H04967.
This work was also supported by MEXT-Supported Program for
the Strategic Research Foundation at Private Universities 2014-
2018, subsidy from MEXT and Kindai University. K. N. is
grateful to the Japan Society for the Promotion of Science
(JSPS) for a Research Fellowship for young scientists. A.T. is
grateful for financial support from the Faculty of Science and
Engineering, Kindai University.
Notes and references
1
P. T. Anastas and J. C. Warner, Green Chemistry: Theory and
Practice, Oxford University Press, 1998.
2
3
M. A. Fox and M. T. Dulay, Chem. Rev., 1993, 93, 341-357.
G. Palmisano, V. Augugliaro, M. Pagliarob and L. Palmisano,
Chem. Commun., 2007, 3425-3437.
4
G. Palmisano, E. Garcia-Lopez, G. Marci, V. Loddo, S.
Yurdakal, V. Augugliaro and L. Palmisano, Chem. Commun.,
2010, 46, 7074-7089.
Figure 8 Expected reaction process of photocatalytic hydrogenation of BA to CCA over
Rh-TiO2.
5
6
F. Mahdavi, T. C. Bruton and Y. Li, J. Org. Chem., 1993, 58,
744-746.
V. Brezova, A. Blaˇzkova, I. ˇSurina, B. Havlinova, J.
Photochem. Photobio. A, 1997, 107, 233-237.
J. L. Ferry and W. H. Glaze, Langmuir, 1998, 14, 3551-3555.
O. V. Makarova, T. Rajh, M. C. Thurnauer, A. Martin, P. A.
Kemme and D. Cropek, Environ. Sci. Tech., 2000, 34, 4797-
4803.
V. Brezova, P. Tarabek, D. Dvoranova, A. Staˇsko and S.
Biskupiˇc, J. Photochem. Photobio. A: Chem., 2003, 155, 179-
198.
3.7. Expected reaction process
7
8
The expected reaction process of photoinduced ring
hydrogenation of BA to CCA over Rh-TiO2 is shown in Figure 8:
1) By irradiation of UV light, photogenerated electrons (e-) and
positive holes (h+) are formed in the conduction and valence
bands of TiO2, and OA is oxidized by h+, 2) H+ is reduced by e-,
resulting in the formation of AHS over Rh particles and 3) the
aromatic ring of BA is successively hydrogenated by AHS over
Rh particles, resulting in the formation of CCA. Since CCA was
formed in the presence of H2 in the dark at 298 K, AHS would
be essentially the same as that formed in the photocatalytic
process. Self-coupling of AHS resulted in H2 evolution. The rate
of H2 production increased after consumption of BA, which
means that the active species formed on Rh are active for ring
hydrogenation of BA.
9
10 H. Tada, T. Ishida, A. Takao and S. Ito, Langmuir, 2004, 20
7898-7900.
11 H. Tada, T. Ishida, A. Takao, S. Ito, S. Mukhopadhyay, T.
Akita, K. Tanaka and H. Kobayashi, ChemPhysChem, 2005, 6,
1537-1543.
12 S. O. Flores, O. R.-Bernij, M. A. Valenzuela, I. Cordova, R.
Gomez and R. Gutierrez, Top. Catal., 2007, 44, 507-511.
13 H. Kominami, S. Iwasaki, T. Maeda, K. Imamura, K.
Hashimoto, Y. Kera and B. Ohtani, Chem. Lett., 2009, 15, 410-
411.
,
14 K. Imamura, S. Iwasaki, T. Maeda, K. Hashimoto, B. Ohtani
and H. Kominami, Phys. Chem. Chem. Phys., 2011, 13, 5114-
5119.
15 K. Imamura, T. Yoshikawa, K. Hashimoto and H. Kominami,
Appl. Catal. B, Environ., 2013, 134–135, 193-197.
16 K. Imamura, K. Hashimoto and H. Kominami, Chem.
Commun., 2012, 48, 4356-4358.
4. Conclusions
We examined photoinduced ring hydrogenation of BA in an
aqueous suspension of metal (M)-loaded TiO2 in the presence
of OA under an H2-free condition. Among the metal-loaded
TiO2 samples examined in this study, Rh-TiO2 showed
17 M. Fukui, A. Tanaka, K. Hashimoto and H. Kominami, Chem.
Lett., 2016, 45, 985-987.
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