58
Table 2
Synthesis of PCA from l-Lys using various platinized SiO2/void/TiO2 (2-h photoirradiation).
a
b
c
d
Catalyst
Conversion (%)
SPCA (%)
OPPCA (%)
RPCA
YH2 (mol)
SiO2(1.5)/void/TiO2
96
99
85
98
50
46
53
53
70
73
75
75
25
23
24
22
50
67
32
49
SiO2/void/TiO2 + H2SO4
SiO2/void/TiO2 + MPTS
SiO2/void/TiO2 + MPTSf
a
Selectivity of PCA production based on amount of consumed l-Lys.
Optical purity of l-PCA.
b
c
d
f
Rate of PCA formation in the unit of mol h−1
Yield of H2.
.
Photoirradiation time was extended to 2.5 h.
with MPTS being more beneficial. This further proved the possibil-
ity of an acidic microenvironment of the core TiO2 surface induced
by the SiO2 shell and also the MPTS that led to protonation of the ␣-
amino group to result in retardation of the ␣-route, as mentioned
earlier, being the possible reason for the production of optically
pure l-PCA.
University) is gratefully acknowledged for his advice on sample
preparation.
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Acknowledgments
This work was supported by Asian Graduate School of Chemistry
and Materials Science, Hokkaido University and National Science
Fellowship, MOSTI, Malaysia. The authors thank Professors Wataru
Ueda, Toru Murayama and Yuichi Kamiya (Hokkaido University) for
their help in ammonia TPD analyses. Professor Shigeru Ikeda (Osaka