Advanced Materials Research Vols. 550-553

Abstract: The effects of catalyst amount on the yields of levulinic and hydroxymethyl furfural were investigated during conversion of glucose to levulinic acid catalyzed by solid super acid SO₄^2- / TiO₂-Al₂O₃-SnO₂. XRD and XPS were used to analyse the characteristics of solid super acid SO₄^2- / TiO₂-Al₂O₃-SnO₂ before reaction and after reaction. The results showed that: solid super acid SO₄^2- / TiO₂-Al₂O₃-SnO₂exhibited good catalytic activity in the reaction of hydrolysis of glucose to produce levulinic acid. There were three obvious peaks in these XRD spectra. The peaks on 44.6° and 67.1° were the characteristic diffraction peaks of γ-Al2O3. The anatase characteristic diffraction peak was on 37.4°. The catalyst was steady in the process. The binding energy of S 2p was similar to the binding energy of standard S6+ 2p in the S 2p XPS spectrum of solid super acid. O 1s XPS was double-peaked spectrum. The increase of element C was the main reason of inactivation of catalyst.

Abstract: Hydrocarbon fuels produced from methanol was investigated over HZSM-5 zeolite catalysts with different Si/Al ratio. About 40% of hydrocarbon yield can be obtained under the identical reaction condition over the catalysts. HZSM-5 catalyst with lower Si/Al ratio has slightly higher oil yield and less olefin content in gas products, which can be ascribed to the stronger acidity in the catalyst favorable for the conversion of intermediates to aromatics. In addition, a small amount of dimethyl ether (DME) was detected when using HZSM-5 zeolite catalyst with Si/Al ratio of 38, indicating that the intermediates from preliminary methanol reaction not sufficiently convert.

Abstract: Heteropoly acide(HPA), as one kind of solid-super acid catalysts, has been researched and applied extensively. Using SBA-15 and ZSM-5 as carriers, HPA catalysts with different types and contents were applied in this work for the hydrolysis of dimethyl ether(DME). It had been found that ZSM-5 was a proper carrier, and its supported phosphotungstic acid exhibited relatively high catalytic activity in this low-temperature hydrolysis reaction.

Abstract: This paper reviews various catalysts for removal of NOx in SCR,including noble metals,zeolites,metal oxides and so on.These traditional catalysts do not have excellent properties in all aspects such as catalytic activity, thermal stability and resistance against poisoning,so they can hardly be commercialized.However,composite type catalysts and storage-reduction catalyst for removal NOx overcome the above disadvantages of traditional catalysts and have promising prospects.

Abstract: A series of pine char sulfonic acids were prepared via a two-step procedure involving phosphoric acid catalytic charring of pine sawdusts and successively sulfonation of the charred precursors. Solid sulfonic acid material prepared in this new route possessed high sulfonic acid loading with 2.36 mmol g^-1 at the optimal charring conditions of phosphoric acid being 85%, ratio of pine sawdusts and phosphoric acid being 1: 10, charring time being 3 h, charring temperature being 140 °C. Pine char sulfonic acids showed excellent activity in the esterification of n-butanol and acetic acid.

Abstract: In this dissertation, combinatorial chemistry was adopted, and the activities of a series of VCuMn/TiO₂ catalysts prepared by impregnation method for middle-low temperature SCR of NO_x were evaluated. The activity datas showed that 2V2Cu8Mn/TiO₂ exhibited better activity. At 200 °C, above 70% NO_x conversion were both obtained with a gas hourly space velocity of 60,000 h^-1, and NO_x conversion of 2V2Cu8Mn/TiO₂ reached nearly 100% at 275~325 °C. The X-ray diffraction characterization showed that the CuO and Mn₂O₃ phases in VCuMn/TiO₂ catalysts were the main active site and with better SCR activity at middle-low temperature. In addition, sulfur-resistance of VCuMn/TiO₂ catalysts were investigated, NO_x conversion on 2V2Cu8Mn/TiO₂ was above 60% at 250 °C after feeding SO₂ (600 ppm). It can be concluded that the modified VCu/TiO₂ catalyst by adding manganese obtained a good de-NO_x activity in a high sulfur content gas stream.

Abstract: amino- pyridinium salts of mono-substiuted Keggin-polyoxometalate were synthesized and the catalytic performance the oxidation of benzyl alcohol to benzaldehyde under solvent-free conditions with hydrogen peroxide was examined. The influences of the composition of hybrid catalyst and mole ratio of H₂O₂ to benzyl alcohol were discussed, under the testing conditions of 70 oC, catalyst load 0.3 g, benzyl alcohol 2 mL, 30% H₂O₂ 6mL, 5 h, 2-N-(2-pyrindinemethyl) -aminopyridinium salt of FeII substituted phosphotungstate (5b)₄HPW₁₁FeO₃₉ exhibited the best activity, the conversion of benzyl of 95.4% with high selectivity of 98% was achieved, aminopyridine component in hybrid catalyst act as a counterion of polyoxometalate anion as well as a ancillary ligand, the interactions between organic counterion and polyoxometalate anion involve the electrostatic bond NH₃⁺…Fe-POM as well as dative bond pyridine-N→Fe-POM, both affect the redox reactivity of mono-substituted polyoxometalte.

Abstract: In this paper, a wide spectrum responsive LaVO₄/TiO₂ nanocomposite has been characterized by Laser Raman and X-ray photoelectron spectra (XPS). Strong photocatalytic activities of LaVO₄/TiO₂ nanocomposite towards the removal of gaseous volatile organic pollutants (typically aromatic compounds) under visible light irradiation were demonstrated. Moreover, applications were also given for the photocatalytic elimination of gaseous benzene under simulated solar light and UV light irradiation.

Abstract: Synthesis of ethylene carbonate (EC) from urea and ethylene glycol was investigated in a batch reactor using La(NO₃)₃ as catalyst. The reaction was performed under reduced pressure to remove the byproduct ammonia. The effect of various operation conditions such as reaction temperature, reaction time and reaction pressure on the EC yield was explored. It was found that the reaction pressure is a key parameter for the formation of EC. At atmospheric pressure, the reaction cannot happen. As the reaction pressure decreases, the EC yield increases significantly. Under the optimum operation conditions, which are reaction pressure 15 KPa, reaction temperature 413 K, reaction time 3 h, and catalyst concentration 10 wt.%, the EC yield can reach to 93%.

Abstract: A series of Beta, ZSM-5 and MCM-22 zeolites modified with metal ions (such as Fe ³⁺ , Co ²⁺ , Ce ³⁺ , Ni ²⁺ and Cu ²⁺ ) for catalytic decomposition of N₂O were prepared by using wet ion exchange method. The effects of different metal ions, the contents of metal ions and silicon aluminum ratio on catalytic decomposition activities of N₂O were investigated, respectively. The results indicated that Beta with a SiO₂/Al₂O₃=30 and 1% Fe ³⁺ have better catalytic decomposition activities to N₂O, the completed catalytic decomposition temperature to 35% N₂O in the condition of 4000 h^-1 GVSH is 350 ⁰ C.