The synthesis of γ-valerolactone (GVL), a versatile precursor in the manufacture of high-value chemicals such as polymer plasticizer, solvent, jet fuel, and, agrochemicals, has been targeted by many research groups. In this study, we report the catalytic performance of iron-modified palladium supported on titanium oxide (denoted as Pd(5.0)-Fe(5.0)/TiO2; 5.0 was the loading amount of Pd and Fe, respectively) in the selective hydrogenation of levulinic acid (LA) to γ-valerolactone (GVL) in stainless-steel batch reactor system. Pd(5.0)-Fe(5.0)/TiO2 catalyst was synthesized by a simple hydrothermal method at 150°C for 24 h, then followed by reduction with H2 at 500°C for 3 h. The X-ray diffraction (XRD) patterns of Pd(5.0)-Fe(5.0)/TiO2 before and after reduction showed the formation of metallic Pd at 2θ = 40.34° and 47.2° corresponding to Pd(111) and Pd(200), respectively. The hydrogenation of LA to GVL effectively occurred in the H2O solvent, whereas in 2-propanol the formation of ester was the main side product. The highest yield of GVL (52.5%) was obtained over Pd(5.0)-Fe(5.0)/TiO2 catalyst at a temperature of 170 °C, initial H2 pressure of 4.0 MPa, solvent H2O 3 ml at a reaction time of 7 h. The yield of GVL slightly increased to 63.3% when the reaction time was prolonged to 15 h.
Carbon-titanium oxide nanocomposite (denoted as @C-Ti02) was successfully synthesized via hydrothermal method at 150°C for 24 h. The C-Ti02 nanocomposite was furtherly modified by adding an Ag metal dopant (denoted as Ag@C-Ti02) to improve and applied to the photocatalytic degradation of Sasirangan textile wastewater. The composite photocatalysts were characterized by XRD and UV-Vis DRS spectroscopies. XRD patterns showed that Ti02 in @C-Ti02 mainly consisted of a brookite phase, as indicated by a series sharp diffraction peak at 2 = 27.20 (111), 31 -5°( 121) and 55.90 ( 241 ). The calculated band gap energy (£ g ) derived from UV-Vis DRS spectra for Ti02, @C-Ti02, and Ag@C-Ti02 were 2.95 eV, 2.54 eV, and 2.74 eV, respectively. Ag@C-Ti02 photocatalyst was found to be active for the photocatalytic degradation of Sasirangan textile wastewater, as indicated by the change of wastewater color from dark to clear. The quantitative photocatalytic activity of Ag@C-Ti02 was evaluated in the degradation of methylene blue, whereas the conversion of methylene blue was 41.3 %. The addition of Ag to @C-Ti02 is believed to play an essential role in the enhancement of photocatalytic activity.
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