Effect of Relative Humidity on Catalytic Combustion of Toluene over Copper Based Catalysts with Different Supports

The copper based catalysts, CuO/T-Al2O3, CuO/y-Al2O3-cordierite （Cord） and CuO/Cord, were prepared by impregnation method. The catalytic activity of the catalysts was tested in absence and presence of water vapor,and the catalysts were characterized. Temperature program desorption （TPD） experiments or toluene and water on the catalysts were carried out. The influence of water vapor on the activity of the catalysts was discussed. Results showed that addition of the water vapor has a significant negative effect on the catalytic activity of the catalysts.The higher the concentration of the Water vapor in feed steam was, the lower the catalytic activity of the copper based catalysts became, which could be mainly ascribed to the competition of water molecules with toluene molecules for adsorption on the catalyst surfaces. TPD experiments showed that the strength of the interaction between water molecules and three catalysts followed the order： CuO/γ-Al2O3〉CuO/γ-Al2O3-Cord〉CuO/Cord. As a consequence of that, the degree of degradation in the catalytic activity of these three catalysts by the water vapor followed the order： CuO/γ-Al2O3〉CuO/y-Al2O3-Cord〉CuO/Cord. However, the negative effect of the water vapor was reversible.

Kinetic studies of methanol synthesis from CO_2+H_2 over copper based catalysts

The catalytic activity for the synthesis of methanol from carbon dioxide and hydrogen was measured on various binary and ternary catalysts containing copper oxide under a pressure of 10 atm. Among these samples the catalysts, CuO/ZnO/γ-Al_2O_3, demonstrated the highest activity and selectivity to methanol; MnO, as third component, had no promotional effect on the activity of meth- anol formation. Based on a simple power rate law the apparent activation energy estimation and par- tial pressure dependence measurement were accomplished over eight catalysts. The activation energies varied from 40 to 120 kJ / mol depending on the composition of catalysts. The rates of methanol for- mation to be 0.3 -- 0.9 order in H_2 and about 0.1 -- 0.2 order in CO_2 were reported.

Transformation of Ethanol to Ethyl Acetate over Cu/SiO2 Catalysts Modified by ZrO2

Direct transformation of ethanol to ethyl acetate was investigated on a series of Cu（ZrO2）/SiO2 catalysts. Inductively coupled plasma（ICP）, surface area analysis, X-ray diffraction（XRD）, H2-temperature programmed reduc- tion（H2-TPR）, X-ray photoelectron spectroscopy（XPS）, NH3-temperature programmed desorption（NH3-TPD） and Fourier transform-infrared spectroscopy（FTIR） techniques were used to characterize the catalysts. The results reveal that ZrO2 can improve the dispersion of copper species and increase the acidity of the Cu（ZrO2）/SiO2 catalysts. The Cu0 is responsible for ethanol dehydrogenation to acetaldehyde, and both the Lewis acid and Bronsted acid sites were in favor of the selectivity to ethyl acetate. The synergistic effect of Cu0 and an appropriate amount of acidic sites played an important role in the production of ethyl acetate.