Advanced Materials Research Vols. 550-553

Abstract: Lanthanum doping TiO2 were prepared by sol-gel method, an the photocatalytic degradation experiments were performed by using methyl orange solution as a target degradant. The results indicated that Suitable doping quantity of lanthanum can improve the photocatalytic activity of nanometer TiO2 powders. On the basis of 50 mL methyl orange solution what concentration is 20 mg/L, photocatalytic activity is the best when doping quantity of lanthanum were 1.0 wt %. Through the relatively experiments by using sunshine and ultraviolet as light source, the results indicated that the La3+ doping broaden the scope of visible light area what TiO2 response to.

Abstract: Pt catalysts have been researched and used for HI decomposition. Specifically, the effects of supports and reduction temperature on metal dispersion were investigated in this paper. Metal dispersion was high measured, in the order of Pt/Al₂O₃, Pt/ZrO₂, and Pt/SiO₂. HI conversion results coincided with the metal dispersion. With effect on reduction temperature, Pt dispersion was measured as 2.9 %, 26 %, and 60 % each 1173K, 973K, and 773 K. In addition, HI conversion presented 7.8%, 16.3%, and, 19.4% respectively. Consequently, Pt dispersion, influenced by supports and reduction temperature was considered to be crucial role in HI conversion.

Abstract: If the surface of the titanium chips (TC) was modified by thermal treatment under air atmosphere, it could be reused as catalyst support or photocatalytic materials. TC-supported CuO and ZnO catalysts were prepared by impregnation (IMP) method and co-precipitation (CP) method using cupric nitrate and zinc nitrate solution as precursors. Loading of CuO and ZnO on TC was 40.6wt% and 50.3wt%, respectively. The catalytic activity for CO₂ hydrogenation was investigated using a flow-typed reactor under various pressures. Conversion of carbon dioxide to methyl alcohol over the CuO-ZnO/TC catalyst by CP and IMP methods were ca. 22% and ca. 10%, respectively. Conversion of carbon dioxide over CuO-ZnO/TC catalyst by CP method was increased with increasing reaction temperature in ranging of 15atm to 30 atm. Maximum selectivity and yield to methyl alcohol over CuO-ZnO/TC catalyst at 250°C were ca. 90% at 20 atm and ca. 18.2% at 30 atm, respectively.

Abstract: Benzaldehyde 1, 2-propanediol acetal was synthesized from benzaldehyde and 1, 2-propanediol in the presence of ionic liquid [HMIM]HSO₄. The effect of the amount of catalyst, reaction time, reaction temperature, and the molar ratio of raw materials agent on the product yield was investigated respectively. Experimental results demonstrate that ionic liquid [HMIM]HSO₄ is a good catalyst for preparation of benzaldehyde 1, 2-propanediol acetal. Results showed the optimal reaction conditions are as follows: the mole ratio of benzaldehyde to 1, 2-propanediol is 1：1.3, the amount of catalyst is 3.0g, the reaction temperature is 343K, and the reaction time is 4h. The achieved yield of acetal is 78. 7%.

Abstract: A Bi-TiO₂ composite with high photocatalytic activity was prepared using tetrabutyl titanate and bismuth nitrate as raw material by hydrothermal method. The structure was characterized by X-ray diffraction(XRD), transmission electron microscopy(TEM), X-ray energy dispersive spectroscopy(EDS), X-ray fluorescence(XRF) and UV-vis diffuse reflectance spectrophotometer(UV-vis DRS). The results show that anatase nanometer titanium dioxide was prepared, in which Bi³⁺ take the place of Ti⁴⁺. The surface area of the sample was higher, ca.312.6m²•g^-1. Bi doping caused red-shift of the absorption spectrum, and the composite has better Visible-light Response. Bi-TiO₂ shows higher photocatalytic avtivity to the degradation of resorcinol than pure TiO₂. The optimum value of Bi doped was 1.00 %. After 120 minutes illuminating under 70W Halide Lamps, degradation rate of resorcinol can get to 100%.

Abstract: The combustion channel of compact methane reformer includes fuel flow duct, porous layer and solid connector. There are heat transport and multi-component species diffusion/convection processes in porous structure. The transfer processes are coupled with methane catalytic combustion, and affect the performance and stability of reformer. A 3D in-house code has been developed to simulate the mass and heat transfer processes involving chemical reactions in the reformer channel in specific condition (mass fraction of CH₄ YCH₄ is less than 1% in the mixture of methane and air). It shows that, catalytic combustion reactions mainly tack place on the porous layer near inlet with a higher temperature area, the biggest heat flux region from the bottom wall is found near the higher temperature area. The reaction rate of methane, temperature of porous layer and heat flux increase with the increase of YCH₄. In general, 0.4% is an adequate value for YCH₄. The research has a benefit meaning to provide a guideline for the improvement and design for compact methane reformer.

Abstract: In DME to olefins (DTO) reaction, SAPO-34 catalyst with CHA structure is well known to be one of the catalysts with good performance. However, the SAPO-34 catalyst is easily deactivated due to coke deposition during DTO reaction. In this study, MeAPSO-34 catalysts (Me=Mn, Co) were prepared for the increase of the catalyst lifetime and their properties have been characterized by XRD and SEM. The DTO reaction was carried out over the MeAPSO-34 catalysts, and the results were compared with the SAPO-34 catalyst. The lifetime of MeAPSO-34 catalysts with high DME conversion and selectivity of light olefins was prolonged than that of the SAPO-34 catalyst. It may be concluded that the decrease of strong acid sites, which were responsible for the formation of coke, affect on the lifetime of the MeAPSO-34 catalysts. In addition, the CoAPSO-34 catalyst with a Co additive showed the best performance in terms of the catalytic lifetime and the selectivity to light olefins.

Abstract: The Ni-Mo-P amorphous catalysts were prepared by chemical reduction method under different sonication conditions. The catalytic performance of the prepared catalysts in selective hydrogenation of nitrobenzene(NB) to aniline(AN) were characterized by XRD, BET, N₂-adsorption, H₂-TPR and H₂-TPD. The results show that the introduction of ultrasonic can improve the dispersion of the active sites in the catalyst, the particle size of the catalyst is also smaller than the regular prepared Ni-Mo-P amorphous catalyst. And the influences of the sonication power and time on the catalysts were discussed and compared. The optimal sonication condition is 70 W within 25 min, its optimal reaction time is 150 min.

Abstract: Mg-Al composite oxide (MgAlY-LDO) solid base catalysts were prepared via the coprecipitation method, followed by calcinations at high temperatures. Isophorone synthesis from acetone condensation was also investigated. The catalysts were characterized via X-ray diffraction analysis, Fourier transform infrared spectroscopy, CO₂ temperature-programmed desorption, and Brunauer-Emmett-Teller analysis. After doping with Y, the MgAl-LDO showed higher catalytic activity at a reaction temperature of 300 °C, 100 kPa and WHSV 6.3 h^-1. Furthermore, the conversion of acetone and the selectivity of isophorone increased from 17.8% and 11.0% to 37.5% and 58.7%, respectively. These results indicate that the basicity of MgAlY-LDO as well as the number of its strong base centers increased after Y doping. The pore volume and size of MgAlY-LDO increased because of the increased hydrotalcite layer space caused by the big Y³⁺ ion. However, the crystal structure of hydrotalcite was remained. Y₂O₃ was evenly dispersed in MgAlY-LDO at low Y doping amounts. As the doping amount increased, the layer structure of hydrotalcite became distorted, thereby affecting the crystallinity of the hydrotalcite. Some Y³⁺ ions emerged from the Mg²⁺ lattice after doping with a high Y³⁺ concentration.

Abstract: The Sulfur-Iodine thermochemical hydrogen production process (SI process) has been focused as one of the most promising method for hydrogen production by water splitting. SI process consists of three sections as follow; (1) Bunsen reaction, (2) H₂SO₄ decomposition and (3) HI decomposition. The O₂ produced in a H₂SO₄ decomposition section could be supplied directly to the Bunsen reaction section without additional separation. Meanwhile, the reactant solution supplied to a Bunsen reaction section could be supplied as the type of a HI_x (I₂ + HI + H₂O) solution, since only the separation of I₂ in a HIx solution recycled from a HI decomposition section is very difficult. Therefore, we carried out the reaction using SO₂ and SO₂-O₂ mixture gases in presence of the HI_x solution to identify the effect of O₂ in the Bunsen reaction. From the results, the amount of I₂ unreacted under the feed of SO₂-O₂ mixture gases was very small higher than those under the feed of SO₂ gas only, while the amount of HI produced was relatively decreased. In addition, the amount of impurities in each phase produced from the Bunsen reaction with the HIx solution was hardly affected by the O₂/SO₂ molar ratios.