Division of Environmental Science and Engineering, Graduate School of Science and Engineering, Yamaguchi University, Yamaguchi 753-8512, Japan.
J Phys Chem A. 2010 Apr 22;114(15):5092-8. doi: 10.1021/jp911842t.
The photocatalytic degradation of chlorinated ethanes was studied in a tubular photoreactor packed with TiO(2) pellets prepared by sol-gel method. The steady-state condition was not obtained, but the deterioration in the photocatalytic activity was observed during the irradiation. Effects of mole fractions of water vapor, O(2), and C(2)H(5)Cl or C(2)H(4)Cl(2) and reaction temperature on the photodegradation of C(2)H(5)Cl or C(2)H(4)Cl(2) were examined, and these data were compared with those obtained by the photodegradation of chlorinated ethylenes. On the basis of the products detected with and without oxygen in the reactant's gas stream, we proposed the degradation mechanism. Measurement of diffuse reflectance infrared Fourier transform spectroscopy of pyridine adsorbed on the catalysts showed that decrease in the conversion for the photodegradation of C(2)H(5)Cl was attributable to the formation of Brønsted acid sites. Comparison of the data obtained with the TiO(2) and the sulfated TiO(2) (SO(4)(2-)/TiO(2)) pellets indicated that the photodegradation of C(2)H(5)Cl was suppressed by the presence of the Brønsted sites, but that of trichloroethylene was not affected. Such a difference is attributable to the adsorption process of these reactants on the acid sites on the catalyst surface.
采用溶胶-凝胶法制备的 TiO2 颗粒填充在管式光反应器中，研究了氯乙烷的光催化降解。虽然达到了稳态条件，但在照射过程中观察到光催化活性降低。考察了水蒸气、O2、C2H5Cl 或 C2H4Cl2 的摩尔分数以及反应温度对 C2H5Cl 或 C2H4Cl2 光降解的影响，并将这些数据与氯乙烷光降解的数据进行了比较。根据反应物气流中有无氧气检测到的产物，提出了降解机理。催化剂上吸附吡啶的漫反射红外傅里叶变换光谱测量表明，C2H5Cl 光降解转化率的降低归因于 Brønsted 酸位的形成。比较 TiO2 和负载 SO42-的 TiO2（SO42-/TiO2）颗粒获得的数据表明，Brønsted 位的存在抑制了 C2H5Cl 的光降解，但对三氯乙烯的光降解没有影响。这种差异归因于这些反应物在催化剂表面酸位上的吸附过程。
