Advanced Materials Research Vols. 634-638

Abstract: This paper reports the effect of alkali precipitating agents, i.e. KOH and NaOH, on activity and stability of Cu-Mn based catalysts for the water gas shift (WGS) reaction. Structural and texture characteristics of the catalysts were characterized by low temperature N2 adsorption, X-Ray Diffraction (XRD) and TPR techniques. The XRD and low temperature N2 adsorption results showed the two types of precipitators produced different Cu-Mn phases during precipitation and drying. The KOH precipitator resulted in partial precipitation of copper ion and formation of hydrate basic copper sulfate, Cu₄SO₄(OH)₆•H₂O after drying; while the NaOH precipitator led to a completed precipitation of Cu ion and formation of relatively stable Cu₂₊₁O and Mn₃O₄ crystals after drying. These phases formed after precipitation by the KOH and NaOH, however, experienced the same phase change during calcination and activation, namely, they first changed to Cu_1.5Mn_1.5O₄ in calcination followed by the formation of microcrystalline Cu and MnO phases during activation. The Cu-Mn WGS catalysts prepared by the NaOH was found to have larger surface area and more content of Cu and MnO phases after activation, which might be the reasons of higher activity and better stability of the Cu-Mn catalyst.

Abstract: Metal-organic frameworks based on Zn2+ and different aromatic carboxylic acid ligands were prepared and characterized by X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy. They were then used as the catalysts for the transesterification between diphenyl carbonate (DPC) and 1, 4-butyldiol (1, 4-BD) to polycarbonate diol (PCDL). Their catalytic activities in the transesterification process were evaluated by the yield of phenol, and their catalytic activities in the polycondensation process were determined by the number-average molecular weight (Mn) and the hydroxyl value.

Abstract: The effects of Cu/Mn ratio on the activity and stability of Cu-Mn catalysts for the water-gas shift reaction (WGSR) were investigated. Activity tests showed that the Cu-Mn catalyst while the ration of Cu to Mn is 1:1 displayed higher activity and better stability than that of others catalysts. The BET , XRD and TPR results revealed that the Cu-Mn catalyst while the ration of Cu to Mn is 1:1 led to higher surface area, a more stable catalyst structure and suitable reduction performance, in turn leading to better catalytic behavior for the Cu-Mn catalyst.

Abstract: A series of coke samples with loading alkali and alkaline earth metals were prepared by the impregnation method, the NOx emission were investigated in a silica fixed bed reactor in the combustion process of raw coke and coke modified by Na, K, Ca and Mg. The results show that Na, K, Ca and Mg play in-situ catalytic effects on the NOx reduction reactions. When the loading amount of Na2CO3 is 2.0%, the NOx reduction ratio was around 17.4%, when the loading of K2CO3 is 2.0%, the amount of NOx emission is reduced by 26.5%. When the loading of CaCl2 is 2.0%, the amount of NOx emission is reduced by 22.3%. When the loading of MgCl2 is 2.0%, the NOx reduction ratio is about 10.9%.

Abstract: Selective Catalytic Reduction (SCR) processes have been one of the most widely used denitration methods at present and the property of low tempreture catalyst becomes a hot research. The Mn-Ce/TiO₂ catalyst was prepared by incipient impregnation method. The influence of load capacity, reaction temperature, O₂ content, etc. on denitration were studied by a fixed bed catalyst reactor with ammonia gas. Results showed that catalyst with load capacity 18% performed high NO removal rate of 90% at conditions of reaction temperature 160°C, low space velocity, NH₃/NO molar ratio 1: 1, O₂ concentration 6%.

Abstract: One novel dodecyliminodiacetate nickel(II) complexes were synthesized and characterized, and these complexes were used as mimic hydrolytic in catalytic hydrolysis of carboxylic ester (PNPP, p-nitrophenyl picolinate). The analysis of specific absorption spectra of the hydrolytic reaction systems indicated that the catalytic hydrolysis involved the key intermediates formed by PNPP with nickel(II) complexes. The kinetic parameter of PNPP catalytic hydrolysis has been calculated and the activation energy for the catalytic hydrolysis is 1.174 kJ•mol-1.

Abstract: A new type of NZP family compound CaZr4(PO4)6 was synthesized by sol-gel method and coprecipitation method respectively, and the acidity of CaZr4(PO4)6 was modulated by doping aluminum. The phase and pore structure of the samples were characterized by X-ray diffraction (XRD) and N2 adsorption-desorption, the acid catalytic activity of CaZr4(PO4)6 doped by Al were investigated by using alpha-pinene isomerization as probe reaction. The results show that CaZr4(PO4)6 doped with Al element synthesized by sol-gel method have regular mesoporous structure and weak strength acid site, therefore the catalytic activity on these samples for alpha-pinene isomerization is higher than that on the Al doping samples prepared by coprecipitation method.

Abstract: The kinetics of the Diels-Alder reaction of cyclopentadiene with bis(2-ethylhexyl) maleate has been studied at temperatures between 25 and 100 °C and at atmospheric pressure. The influence of temperature on the kinetic constants was determined by fitting the results to the Arrhenius equation. As a result, fitting line similar with the linear curve of the Arrhenius equation at 25, 30 and 40 °C. However, the fitting curve, at 60, 80 and 100 °C, tended towards the outside of the curve in the form of Arrhenius equation. The ratio of endo/exo was a slight change from increase of the reaction temperature.

Abstract: Based on the mechanism of ClO₃^-/Cl^- reaction system, the kinetics for reaction of sodium chlorate and hydrochloric acid to generate ClO₂ was studied. The rate equation of this reaction system was deduced and simplified as a formula with mixed-order (combination of first-order and second-order) towards ClO₃^-. This rate formula indicates that the initial rate of the reaction is the first-order with respect to ClO₃^-, and the reaction rate is the second-order with respect to ClO₃^- when [ClO₃^-] becomes close to zero. The rate constants of the first-order were determined as 0.0168s^-1(30°C), 0.0221s^-1(40°C), and 0.0279s^-1(50°C), respectively, and that of the second-order were obtained for 0.0019L·mol^-1·s^-1(30°C), 0.0028L·mol^-1·s^-1(40°C), and 0.0060L·mol^-1·s^-1(50°C), respectively. The results of statistic test prove that the rate formula obtained in this work is credible.

Abstract: The performance of ZrO₂-La promoted silica supported cobalt catalyst (100Co/15ZrO₂/ 100Aerosil/0.66La) was compared to the ZrO₂-Ru promoted one, 100Co/15ZrO₂/100Aerosil/0.66Ru, in Fischer-Tropsch synthesis (FTS). These catalysts were prepared by co-precipitation and incipient wetness impregnation methods. The characterization by XRD confirmed the cobalt phase of Co3O4 in both catalysts. For their catalytic activity on FTS reaction, the results preliminarily showed the higher methane fraction (60-80%) and lower C₂-C₄ (10-20%) and C₅₊ (10-20%) fractions in ZrO₂-La promoted catalyst compared to the fractions of methane (20-40%), C₂-C₄ (20-50%), and C₅₊(10-60%) from the ZrO₂-Ru promoted catalyst. During reaction, the maximum n-paraffin selectivity of 40% was at C₃ and the hydrocarbon chain was up to C₆ for the ZrO₂-La promoted catalyst. For the ZrO₂-Ru promoted catalyst, the result showed the maximum n-paraffin of C₃ at 30 min of reaction time. When the reaction time increased, the maximum n-paraffin selectivity shifted toward higher C number but levelled off (15%) and the hydrocarbon chain was up to C₁₆.