Advanced Materials Research Vols. 550-553

Abstract: Ethyl acetate was synthesized by catalytic distillation using packing solid super acid catalyst of SO₄^2-/Al₂O₃ made by oneself. The effects of process parameters such as the ratio between acetic acid and ethanol, the feed flow rate of ethanol and reflux ratio on catalytic distillation were observed. The best operation parameters were determined. It was beneficial for synthesis of ethyl acetate when n(acetic acid)/n(ethanol) was 1/3, the feed flow rate of ethanol was 3mol/l and reflux ratio was 2.

Abstract: Polymerization of β-pinene was investigated in the presence of various Keggin phosphotungstates. The experiments show that cetyltrimethylammonium phosphotungstate with molar ratio of cetyltrimethylammonium bromide to phosphotungstatic acid equal to 0.5 indicate efficient catalytic performance for the polymerization of β-pinene. The catalyst was easily removed from reaction mixture by filtration. Therefore, a clean and environmental friendly strategy for synthesis of terpene resin is developed.

Abstract: The oxidative ethylbenzene dehydrogenation to styrene with CO₂ has been studied using various catalysts to enhance its activity and stability. The type of V₂O₅-Fe₂O₃/A_l2O₃-TiO₂ catalyst is studied to fit for this process. It is found that different TiO₂ loadings can lead to the activity difference. Compared with the results happened in N₂ atmosphere, both activity and selectivity were lower than that in the CO₂. Hence, CO₂ was chosen as a soft oxidant by improving activity and selectivity in the process of oxidative ethylbenzene dehydrogenation to styrene with CO₂ over the investigated catalysts.

Abstract: Metal-substituted mesoporous aluminophosphates with high thermal stability (Fe-JLU-50 and Cu-JLU-50) has been prepared by using preformed microporous aluminophosphate precursors. The materials were characterized by X-ray diffraction, nitrogen adsorption/desorption isotherms and FT-IR spectroscopy. The characterization results showed the presence of zeolite aluminophosphate structural building units in the framework of the mesoporous aluminophosphates, which is responsible for their highly thermal stability. Also, the metal species such as Fe and Cu were successfully incorporated in the framework of the mesoporous aluminophosphates via this approach. Fe-JLU-50 and Cu-JLU-50 were evaluated in the oxidations of phenol and trimethylphenol (TMP) with aqueous H2O2, giving highly catalytic activities in both reactions. This result suggests that the materials are versatile catalysts for both small and bulky substrates, ascribed to the accessibility of the substrates to the active sites in the framework of Fe-JLU-50 and Cu-JLU-50 by the retained mesopores after calcination.

Abstract: The present work aimed to find reasons for different catalytic ability of the Nieuwland catalyst and anhydrous catalyst in dimerization of acetylene to produce Monovinylacetylene (MVA). The results showed the catalytic ions in the Nieuwland catalyst and the anhydrous catalyst were CuCl^-₂ and Cu₂Cl^-₃ respectively by studies on the Cu-containing crystals recovered from corresponding catalyst. CuCl^-₂ in crystal A and Cu₂Cl^-₃ in crystal B has similar crystal structure, however, Cu(Ι) in Cu₂Cl^-₃ has higher electron density due to stronger bond energy of Cu(Ι)-Cl, which may contribute to the higher activity of the anhydrous catalyst than that of Nieuwland catalyst.

Abstract: We investigated the Ni/ZrO₂ catalyst performance of YBa₂Cu₃O_7-x (YBCO) membrane reactor in the process of partial oxidation of methane (POM) to syngas by TG. The activity of the catalyst effected not only on the methane conversion but also CO selectivity. The effect of temperature on CO selectivity was little and could be neglected.The change of CH₄ conversion along time was caused by the deactivation of catalyst or/and the decay of membrane reactor. The loss of catalysts increase with temperature accoding to the carves of TG .

Abstract: The adsorption behavior of ethylene and propylene in zeolite ZSM-5 was studied by Grand Canonical Monte Carlo (GCMC) simulations. It is found that ethylene and propylene molecules show different adsorption behaviors in the zeolite cavum. The adsorption isotherms of ethylene and propylene in ZSM-5 at 298K and 823K were simulated. The results exhibit that the molecular adsorption is influenced at various temperatures and pressures, leading to different rules for the adsorption of ethylene and propylene molecules in zeolite. At low temperature, when the pressure is enhanced from 100kpa to 1000 kpa, the adsorption amounts of olefin molecule increase obviously and the loading of ethylene are significantly larger than those of propylene. The adsorption of propylene has a preferential adsorption site in cross position, and nearly reaches saturation at pressure higher than 300kPa. While at 823K the adsorption of ethylene is inhibited with lower loading than those of propylene.

Abstract: Carbon deposits play a crucial role in the performance of catalysts, in terms of controlling both reaction selectivity and activity, this is most often manifest through catalyst deactivation. Understanding the structure and electronic properties of the carbon deposits formed on the surface of a catalyst is therefore an importance key. In this study the catalytic performance of Ni based on Y-Zeolite (CBV300) prepared by incipient wetness impregnation. The prepared catalyst was tested in a micro tubular reactor using temperature ranges of 500, 600 and 700 °C at atmospheric pressure, using a total flow rate of 36 ml/min consisting of 2 ml/min of N₂, 17 ml/min of CO₂ and 17 ml/min of CH₄. The calcination was carried out in the range of 500–900 °C. The catalyst is activated inside the reactor using hydrogen gas.The conversion of CH₄ observed over 5wt%Ni/ Y-Zeolite at 700 °C were 59.6%. The supported Ni catalysts were characterized by BET and TG/DTA techniques.

Abstract: In this study, spinel-typed ZnFe₂O₄ was synthesized through Sol-Gel method, using fresh egg white as a complexing agent, and characterized by XRD and SEM. Then, the synthesized sample was used as the photo-Fenton heterogeneous catalyst for the discoloration of methyl orange (MO) in solution. The XRD results show that the synthesized sample was pure, only with the spinel structure, when the volume ratio of the fresh egg white/ferric nitrate/zinc nitrate was 2:2:1. And the lowest sintered temperature to obtain the single-phase ZnFe₂O₄ was 500°C. The SEM results reveal that the ZnFe₂O₄ crystalline grains presented irregular shapes and desultorily aggregated together, with a average diameter of 150-250nm. The experimental results show that MO could be efficiently discolored in photo-Fenton system of ZnFe₂O₄ and H₂O₂, under UV irradiation. MO discoloration ratio increased as H₂O₂ dosage increasing. The optimum dosage of ZnFe₂O₄ was 1g/L in this study. With the MO initial concentration increasing, MO discoloration ratio decreased. The ZnFe₂O₄ sample obtained at 500°C exhibited the optimum MO discoloration ratio. Finally, the mechanism for MO discoloration in the photo-Fenton system was discussed.

Abstract: Mesoporous silicas SBA-15 with Ag nanoparticles in the channel was synthesized by one-step method. Samples characterzation were performed by the XRD, TEM, adsorption/desorption of nitrogen and ICP-AES. And the heterogeneous catalysis(Ag/SBA-15) shows catalytic activity in three-component coupling reaction of aldehyde, alkyne, and amine.