Papers by Keyword: Catalysis

Abstract: An L-proline-catalyzed synthesis of amino thiazoles is described here. Amides and 2-mercapto thiazoles were used as the starting reagents. Various reaction conditions were screened, and the scope of various amides and 2-mercapto thiazoles has been examined. Most of the substrates gave high yields. Compared with traditional synthetic methods with transition metal as catalyst, this protocol uses organocatalyst L-proline. It will reduce environment pollution and save the synthetic cost.

Abstract: To promote the alcohol catalytic oxidation of Pd/C catalysts, it was implemented that the lanthanide Yb was introduced to the catalyst via the precipitation thermal decomposition and chemical reduction methods. The structure analysis and surface morphology of Pd-Yb/C catalysts were investigated by XRD and SEM. The ethanol electrocatalytic oxidation activity of in alkaline media was studied by cyclic voltammetry. The results show that the performance of ethanol catalytic oxidation on Pd-Yb/C electrode is better than that on the Pd/C electrode. The introduction of Yb can promote Pd/C catalytic oxidation alcohol and its poisoning tolerance ability.

Abstract: A study for optimizing the experimental conditions for the hydrolysis of polyethylene terephthalate (PET) catalyzed by carbonates was performed. The main influence factors of PET microwave hydrolytic reaction, such as the reaction temperature, time and catalyst dosage, were confirmed and these effects on the catalysis of PET microwave hydrolysis were studied in detail. The results showed that the sequence of influence factors was reaction temperature>reaction time> catalyst dosage. The optimal experimental conditions under the catalyst of basic zinc carbonate were that the catalyst dosage, 0.75%; the reaction time, 210 min; the reaction temperature, 200°C.

Abstract: A new environmental friendly catalyst, H₄SiW₆Mo₆O₄₀/TiO₂-SiO₂ was prepared by impregnation method, the synthesis of cyclohexanone 1,2-propanediol ketal was the probe reaction to optimize the synthetic condition of catalyst. The reactive condition of catalyst was optimized by orthogonal test method. The optimum conditions are n (TiO₂): n (SiO₂)= 3: 1, 20 % mass ratio of m (H₄SiW₆Mo₆O₄₀): m (TiO₂-SiO₂), the calcined time is 3 h and 300 °C of activated temperature. Using H₄SiW₆Mo₆O₄₀/TiO₂-SiO₂ as catalyst, adipic acid was synthesized from the oxidation of cyclohexanone by 30 % H₂O₂. Influences of dosage of H₄SiW₆Mo₆O₄₀/TiO₂-SiO₂, reaction temperature, volume of hydrogen peroxide and reaction time were discussed. Experimental results showed that H₄SiW₆Mo₆O₄₀/TiO₂-SiO₂ is a good catalyst for synthesis of adipic acid. When n (cyclohexene): n (H₂O₂): n (H₄SiW₆Mo₆O₄₀/TiO₂-SiO₂)= 100: 979: 0.04, reaction temperature is 130 °C and reaction time is 5 h, under the optimum conditions, the yield of adipic acid is 45.9 %.

Abstract: The environmental friendly catalyst, H₄SiW₁₂O₄₀/TiO₂-SiO₂ was prepared by the impregnation method. The synthesis of cyclohexanone glycol ketal was as the probe reaction and investigated the different influences on the catalytic activity of H₄SiW₁₂O₄₀/TiO₂-SiO₂ by the quality of the carrier TiO₂-SiO₂ ratio, load of heteropoly acid, catalyst preparation conditions of the activation time and the calcination temperature, etc. The results showed the best condition for the preparation of the catalyst is the mass ratio of TiO₂ and SiO₂ is 1: 5, the load ratio of H₄SiW₁₂O₄₀ is 10 %, calcination temperature is 300 oC and the roasting time is 3.0 h. Under the condition of the molar ratio of aldehydes (ketones) and glycol (1,2-propanediol) is 1: 1.6, the mass percent of the catalyst is 1.4 %, and the reaction time of 70 min, the yields of eight kinds acetal (ketal) are 71.6 %~ 90.5 %.

Abstract: A new ZrCl₄-catalyzed method for the preparation of an asymmetrical benzimidazole derivative has been developed. Further alkylation of the benzimidazole precursor with methyl iodide afforded a new monomethine cyanine derivative. The photophysical evaluation showed that the newly synthesized monomethine cyanine compound was non-fluorescent.

Abstract: Amyl ferulate was synthesized by direct esterification with using sodium bisulfate supported by silica as a catalyst, ferulic acid and n-pentanol as raw materials. The influences of some factors on the synthetic process were studied. The optimal reaction conditions based upon 0.2 mol of ferulic acid were chosen that the molar ratio of n-pentanol and ferulic acid was 2 : 1, the mass ratio of catalyst to reactants was 6%, refluxing reaction time was 3 hours. The yield of the product reached 97% under the above conditions. The structure of the product was characterized by IR, 1H NMR and MS spectrum. The catalyst could be recycled and used for many times.

Abstract: This paper represents the results of researching of recycling plastic wastes by hydrogenation in the presence of catalysts: natural zeolite, bauxite, red sludge (wastes from recycling of bauxite), as a hydrogen source was used heavy residues from oil process. This method allowed to define the optimal conditions of the hydrogenation process and get liquid products enriched with isoalkanes, cycloalkanes, aromatic and heteroaromatic hydrocarbons.

Abstract: Nanomaterial based electrochemical method gain tremendous interest for the detection of biomolecules due to high sensitivity, selectivity, and low fabrication cost. High surface to volume ratio, excellent electrocatalytic properties of the nanomaterials plays important role for the sensitive and selective detection of biomolecules. For electrochemical biosensors, proper control of chemical, electrochemical and physical properties, as well as their functionalization and surface immobilization significantly influences the overall performance. This chapter gives an overview of the importance of the development of nanomaterials based electrochemical biosensors; particularly direct electrooxidation-or electroreduction-based biosensors, catalysis-based biosensors, and label-based affinity biosensors. In addition, fabrication methods including modification of electrode surface with nanomaterials, tailoring their physico-chemical properties, and functionalization with chemicals or biomolecules are also highlighted.

Abstract: The monodisperse Mn₂O₃ nanooctahedron, Mn₃O₄ nanorices, NiO nanoflowers and Cu₂O nanoroses have been synthesized via a facile solvothermal approach in the presence of poly (vinyl-pyrrolidone)/stearic acid (PVP/SA) as capping agent. Field-emission scanning electron microscopes (FESEM) and X-ray powder diffraction (XRD) were employed to detect the prepared products. Furthermore, the synthetic method appears to be a general approach and other metal oxide materials with various well-defined nano/microstructures can be fabricated by the similar method. The as-obtained metal oxides nanostructures were used as catalyst in CO oxidation, and the octahedral Mn₂O₃ nanoparticles exhibited relatively high activity. Complete conversion CO to CO₂ can be achieved at a temperature as low as 240 °C over Mn₂O₃ catalyst, which was about 70 and 100 °C lower than that of Mn₃O₄ and NiO, respectively.