Fig. 1 illustrates the preparation procedures. The
TiO2 Degussa-P25 powder was used as a reference catalyst.
Modified catalyst was prepared by impregnating
Degussa-P25 with copper nitrate solution to give copper
content that varies between 0.5 and 10 wt%. The improved-
impregnation method was done by sonication
of the impregnated TiO2 slurry, stirring of the slurry
at 95 C, drying followed by calcination, and reduction–
oxidation treatment to form Cu0/TiO2 and CuI/
TiO2 catalysts. Product of the atmospheric calcination
step is predicted to be in the form of CuO/TiO2. Reduction
step under 100 ml/min of 20%H2/He mixture at
300 C for 3 h was completed to make a metallic copper
form (Cu0/TiO2). The final step of oxidation was performed
under 100 ml/min of N2O at 80 C for 3 h to
get Cu2O/TiO2. Only surface copper was selectively oxidized
by N2O when the oxidation temperature was less
than 100 C [1].
The crystalline phase of the samples were determined
using powder X-ray diffraction (XRD). The XRD patterns
were obtained from a PHILIPS PW 1710 using
Ni-filtered Cu Ka radiation (k = 0.154184 nm) that
operated at 40 kV and 30 mA. The 2h scanning range
was 23–63 with a step size of 0.01 and a time per step
of 1.0 s. The crystallite sizes of the samples were estimated
from FWHM (full-width at half-maximum) of
XRD by Scherrer equation. A Cary 2415 UV–vis–NIR
spectrophotometer equipped with an integrated sphere
was used to record the diffuse reflectance spectra
(DRS) of the samples. The reflectance spectra of the
samples were analyzed under ambient condition in the
wavelength range of 340–700 nm. Copper concentration
in the catalysts was measured by atomic absorption
spectroscopy (AAS) using Chem. Tech Analytical 2000
spectrophotometer. The specific surface area of catalysts
was measured by multipoint BET of N2 adsorption in a
Quantachrome Autosorb-6. A SEM 515 PHILIPS scanning
electron microscope (SEM) equipped with EDAX
PV9900 PHILIPS energy dispersive X-ray (EDX) and
Mapping was conducted at 15 and 22 kV to observe
the morphology of catalysts, to perform semi-quantitative
analysis, and to analyze distribution of Cu and Ti,
respectively.
Fig. 1 illustrates the preparation procedures. The
TiO2 Degussa-P25 powder was used as a reference catalyst.
Modified catalyst was prepared by impregnating
Degussa-P25 with copper nitrate solution to give copper
content that varies between 0.5 and 10 wt%. The improved-
impregnation method was done by sonication
of the impregnated TiO2 slurry, stirring of the slurry
at 95 C, drying followed by calcination, and reduction–
oxidation treatment to form Cu0/TiO2 and CuI/
TiO2 catalysts. Product of the atmospheric calcination
step is predicted to be in the form of CuO/TiO2. Reduction
step under 100 ml/min of 20%H2/He mixture at
300 C for 3 h was completed to make a metallic copper
form (Cu0/TiO2). The final step of oxidation was performed
under 100 ml/min of N2O at 80 C for 3 h to
get Cu2O/TiO2. Only surface copper was selectively oxidized
by N2O when the oxidation temperature was less
than 100 C [1].
The crystalline phase of the samples were determined
using powder X-ray diffraction (XRD). The XRD patterns
were obtained from a PHILIPS PW 1710 using
Ni-filtered Cu Ka radiation (k = 0.154184 nm) that
operated at 40 kV and 30 mA. The 2h scanning range
was 23–63 with a step size of 0.01 and a time per step
of 1.0 s. The crystallite sizes of the samples were estimated
from FWHM (full-width at half-maximum) of
XRD by Scherrer equation. A Cary 2415 UV–vis–NIR
spectrophotometer equipped with an integrated sphere
was used to record the diffuse reflectance spectra
(DRS) of the samples. The reflectance spectra of the
samples were analyzed under ambient condition in the
wavelength range of 340–700 nm. Copper concentration
in the catalysts was measured by atomic absorption
spectroscopy (AAS) using Chem. Tech Analytical 2000
spectrophotometer. The specific surface area of catalysts
was measured by multipoint BET of N2 adsorption in a
Quantachrome Autosorb-6. A SEM 515 PHILIPS scanning
electron microscope (SEM) equipped with EDAX
PV9900 PHILIPS energy dispersive X-ray (EDX) and
Mapping was conducted at 15 and 22 kV to observe
the morphology of catalysts, to perform semi-quantitative
analysis, and to analyze distribution of Cu and Ti,
respectively.
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