Advanced Materials Research Vols. 634-638

Abstract: Lipase-catalyzed esterification of caffeic acid with 1-propanol, to form caffeic acid propyl ester (CAPE), was investigated in ionic liquid using immobilized lipase. Ten ILs were used as the reaction medium; three types of lipases were selected as biocatalysts, and the lipase-catalyzed synthesis properties of CAPE were measured systematically in order to enhance the yield of CAPE. The results indicated that when [Bmim][Tf2N] was selected as reaction media, Novozym 435 was used as catalyst, the molar ratio of 1-propanol to CA was 10:1, the reaction temperature was 80 °C, and the mass ratio of catalyst to CA was 18:1, the highst yield of CAPE attained 41.0 %.

Abstract: Color of rosin is an important evaluation quality index. A process for preparing light-color rosin by adding different chemical additives in the reaction was studied. The results showed that the best light-color rosin can be produced by adding TM430 and TM923. Mechanism of decoloration was studied by ultraviolet spectra. The Gardner color of rosin was reduced from 7 to 2 and the acid value and softening point changed a little where the TM430 dosage of 0.2% based on the weight of the starting rosin, in atmospheres of nitrogen for protection, reaction time for 2h. The decoloration mechanism was analyzed with UV.The hydrogen atom generated by disproportionate catalytic reaction with TM430. The color substances in the raw rosin were reduced to colorless by hydrogen atom generated by catalytic of TM430.

Abstract: The LaBO3/HZSM-5 samples were prepared by the impregnation method. The structure of catalysts was examined by XRD. The catalytic activity for the combustion of soot particulate was evaluated by a technique of the temperature-programmed reaction. In the LaBO3/HZSM-5 catalyst, the Mn as B-site ion, the catalyst was the good candidate catalyst for the soot catalytic combustion. In the LaMnO3/HZSM-5 catalyst, the catalytic activity was tunable by changing the metal components of the perovskite-type oxide at B-site, the Fe partial substitution for Mn of LaMnO3/HZSM-5 enhanced the catalytic activity, and the combustion temperature of soot particle was lower than LaMnO3/HZSM-5 sample without substitution, corresponding Tm of 401oC and the selectivity of CO2 77.0%.

Abstract: Mn-Ce-Fe Oxide catalysts were prepared by a co-precipitation method using precipitants NH4OH. The catalysts were characterized by Powder X-ray Diffraction (XRD), Transmission Electron Microscopy (TEM) and BET study. It was found that the samples prepared with NH4OH as a precipitator show higher surface areas and s_{Subscript text}uperior catalytic performance at room temperature. The catalysts would reduce substantially indoor formaldehyde concentrations in the present of airstreams.

Abstract: Palladium-Gold(Pd-Au)/4A zeolite catalyst was prepared by using 4A zeolite as carrier and Pd-Au as active components. The structure of Pd-Au/4A zeolite catalyst was characterized by a combination of atomic absorption spectrometry (AAS), scanning electron microscopy (SEM) and X-ray diffraction (XRD).The AAS testing showed that Pd and Au supported rate were increased up to the maximum 93.88% and 90.22% respectively at the ratio of Pd/Au=1.16. The SEM analysis results indicated that Pd-Au alloy particles of 4A zeolite catalyst can grown up and reunited obviously through before and after reaction. The XRD analysis results showed that diffraction peak of Pd(111), Pd(200), Au(111) and Au(200) became sharp gradually with the extension of reaction time, crystalline phase composition and grain size of catalyst became bigger gradually. The catalytic activity of the Pd-Au /4A zeolite catalyst was elaborated in vinyl acetate synthesis and the results showed that Pd-Au/4A zeolite catalyst has excellent catalytic activity.

Abstract: A series of TiO2-Al2O3 composite supports were prepared by hydrolysis and deposition of tetrabutyl titanate on macropore Al2O3, and the nickel phosphide catalyst, Ni2P/TiO2-Al2O3, Ni2P/TiO2 and Ni2P/ Al2O3 were prepared by incipient wetness impregnation and in situ H2 reduction method. Their hydrodenitrogenation(HDN) performance were evaluated on a continuous-flow fixed-bed reactor by using quinoline as the model molecules . The results show that the TiO2-Al2O3 composite support still retained the pore properties of macropore Al2O3, and anatase TiO2 were well dispersed on the Al2O3 surface. Different supports had great influence on the reduction behaviour of the oxidic precusors and HDN activity of phosphide catalysts.The main active phase after reduction was Ni2P phase for the TiO2 supportd catalyst, but only Ni12P5 appeared for the TiO2-Al2O3 and Al2O3 supported catalyst. The TiO2-Al2O3 supported catalyst with the Ti /Al atomic ratio of 0.12 exhibited the highest HDN activity among all catalysts.

Abstract: Acidity is a very important character of ionic liquids, which determines the application of ionic liquids in catalysis. In some cases, the adjustment of ionic liquids acidity becomes important and necessary. Focusing on acidic ionic liquids, researches on determination of acidity, application of acidic ionic liquids in alkylation, acidic adjustment methods and novel acidic ionic liquids were reviewed. Finally the development of acidic ionic liquids is discussed.

Abstract: The effects of temperature and hydrogen partial pressure on 4-Carboxybenzaldehyde (4-CBA) hydrogenation over Pd/TiO2 catalyst were investigated in a batch reactor. The results show that 4-CBA hydrogenation is a consecutive reaction. And 4-CBA hydrogenation to 4-hydroxymethylbenzoic (4-HMBA) is a reversible exothermic reaction. Meanwhile, a parallel reaction of 4-CBA decarbonylation occurs during the process. The hydrogenation rate of 4-HMBA is more sensitive to temperature and hydrogen partial pressure than that of 4-CBA. Macro-kinetics of 4-CBA reaction over Pd/TiO2 was obtained from the experimental data using the power-law kinetics model. The apparent activation energies of 4-CBA hydrogenation, 4-HMBA hydrogenation, 4-CBA decarbonylation and 4-HMBA dehydrogenation are 29.65 kJ/mol, 42.55 kJ/mol, 74.32 kJ/mol and 69.34 kJ/mol, respectively. The reaction orders with respect to 4-CBA and 4-HMBA are both first-order.

Abstract: Nanocrystalline TiO₂ with the average crystallite sizes of 9 and 18 nm were synthesized by the solvothermal method and employed as supports for preparation of Co/TiO₂ catalysts for CO hydrogenation reaction with various Co loadings between 5-20 wt%. For a similar Co loading, the use of larger crystallite size TiO2 resulted in higher higher CO hydrogenation activities with no influences on the product selectivities. However, an optimum amount of cobalt loading that maximized CO hydrogenation activity of Co/TiO₂ was determined to be at ca. 15 wt.% for both TiO2 crystallite sizes.

Abstract: The alkyl oleates were prepared by esterification of oleic acid with alkyl alcohols catalyzed by the lipase from Candida sp. 99-125 in solvent-free system. The influence of several factors, including enzyme concentration, temperature, molar ratio between oleic acid and alkyl alcohols and the structures of alcohols, was also investigated. The results indicated that the reactions catalyzed by lipase at 20 oC, in the presence of 5% (w/w) lipase, on the molar ratio of 1:1 between oleic acid and alcohols, afforded products in high yield and showed high selectivity to the alcohols with less hindrance on hydroxyl group. The lipase from Candida sp. 99-125 was identified to be an effective catalyst in the esterification of alcohol and oleic acid at low temperature.