Advanced Materials Research Vols. 881-883

Abstract: In this paper, the prenyl alcohol was catalyzed synthesized in anhydrous system by using isoprene and dichloroacetic acid as raw material and sodium dichloroacetate as catalyst. The obtained product was mainly characterized by FT-IR and GC. Furthermore, the olefine acid ratio, reaction time, amount of catalyst, saponification time and NaOH concentration were systematically investigated during the work. The optimum reaction conditions are as follows: the olefine acid ratio was 1:2, reaction time was 2h, amount of catalyst was 1.8g, saponification time was 2h and NaOH concentration was 4mol/L, the yield of prenyl alcohol was 45%.

Abstract: A series of TiO₂-Al₂O₃ composite supports were prepared by co-precipitation of titanium sulfate and aluminium nitrate , and the nickel phosphide catalysts were prepared by incipient wetness impregnation and in situ H₂ reduction method. The catalysts were characterized by XRD, N₂ adsorption, TPR, TEM and XPS techniques. Their hydrodenitrogenation (HDN) performances were evaluated by using quinoline as model molecules . The results show that TiO₂ was evenly dispersed on massive γ-Al₂O₃ surface. The introduction of TiO₂ weakened the strong interaction between Al₂O₃ and phosphate, and improved the reducibility of the precursors , facilitating to the formation of Ni₂P active phase. TiO₂ acted as an electronic promoter for the Ni-P catalyst and enhanced both the hydrogenation and C-N bond cleavage activities. Different Ti / Al molar ratio had great influence on HDN activity of the catalyst. The Ni₂P /TiO₂-Al₂O₃ with Ti/Al ratio of 1/8, exhibited the highest activity for quinoline HDN.

Abstract: With cobalt-based catalyst loaded by Al₂O₃, TiO₂ and ZrO₂ as research objectives, in this paper, the performance of these cobalt-based catalysts in Fischer-Tropsch synthesis is discussed. Besides, BET, XRD, FTIR, TPR superficial characteristics and evaluation experiments have been carried out for these catalysts respectively, and the result shows that, the catalyst loaded by ZrO₂ has the highest catalytic activity, while the catalyst loaded by Al₂O₃ has the lowest catalytic activity. The catalyst with higher CO adsorption and dissolving capacity has higher activity; meanwhile, the higher reducibility the catalyst has, the higher the activity of the catalyst will be. In addition, catalyst methane selectivity loaded by Al₂O₃ is the highest, while catalyst methane selectivity loaded by TiO₂ is the lowest, which shows that the large pore structure of catalyst is good for heavy hydrocarbon production, meanwhile, formate species generated on the surface of catalyst implies that the formate species is involved in the generation of methane. Keywords.Carrier; cobalt-based catalyst; Fischer-Tropsch synthesis; performance

Abstract: ZnO photocatalyst was prepared by sol-gel method with the assistance of cetyltrimethylammonium bromide (CTAB). The specific surface area and structure were characterized by Brunauer-Emmett-Teller (BET) method and X-ray diffraction (XRD), respectively. The photocatalytic activity of ZnO prepared for decolorization of methyl orange (MO) aqueous solution was evaluated. The results show that ZnO (mol ratio of ZnO/CTAB is 10) baked at 500°C holds the best photocatalytic activity.

Abstract: Hydrothermally stable mesoporous aluminosilicates with tubular morphology and hexagonal nanochannels were prepared by a new route. The route is different from conversational method of highly ordered MCM-41 assembled from Beta zeolite seed colloidal. The synthesis of Beta zeolite-like seeds is a novel route of acid treatment. The XRD results indicated that the synthesized materials were well-ordered hexagonal mesostructures of MCM-41. The highly regular hexagonal mesostructures could survive by steaming at 750 °C for 2 h, exhibiting good hydrothermal stability. Combining the SEM investigation, the as-made materials showed tubular morphology with diameter of 0.4 μm. The sample has a stronger acid strength, and was used as the support of a Pd-Pt catalyst for the polyaromatics hydrogenation. It has high activity and good sulfur tolerance towards hydrogenation of aromatics of smaller diameter. It was demonstrated that the introduction of building units of Beta zeolite enhances the activity of polyaromatics hydrogenation. It can be concluded that the pore structure and acidity of support is a key factor for the design of a sulfur tolerant noble metal catalyst for aromatics saturation of diesel.

Abstract: The Ir/AlO(OH) catalyst was prepared by sol-gel method and used for selective hydrogenation of p-chloronitrobenzene (p-CNB) to p-chloroniamine (p-CAN). The mechanism of p-CNB hydrogenation over the catalyst was discussed. The hydrogen bond between the surface hydroxyl groups of the catalyst and the nitrogen present in p-CNB facilitated the hydrogenation of nitro group. On the other hand, the formation of hydrogen bond between the hydrogenation product and water promotes the rapid desorption of the hydrogenation product on the surface of the catalyst. Thus the activity and selectivity were greatly promoted.

Abstract: The reactivity of olefins and S-compounds and their distributions in different catalyst-bed lengths were experimentally evaluated with a FCC gasoline in a high-pressure fixed-bed continuous flow pilot unit over the CoMoS/γ-Al₂O₃ catalyst. The evaluation results demonstrated that the increased steric hindrances around the double bond (C=C) and that to the thiophene molecules could suppress the hydrogenation of olefins and hydrodesulfurization (HDS) of S-compounds, respectively. Meanwhile, the reaction temperatures could influence the acidic property of the CoMoS active phase confirmed by FT-IR analysis, and thus induced the different reactions. It was found that the isomerization of terminal olefins to internal olefins was promoted by the Brønsted acid sites (-SH) at low temperatures, as well as the skeletal isomerization by the strong Lewis acid sites occurred to a minor extent at high temperatures. Besides, the distributions of olefins and S-compounds in different catalyst-bed lengths showed that the removal of S-compounds reached 80% of its maximum conversion at the first 40% of the reactor length, however, the saturation of olefins increased linearly as the reactor length increased. Therefore, a new catalyst-loading method was developed, i.e., the upper 40% of the reactor length filling with catalyst of high HDS activity and the bottom 60% with catalyst of low olefin saturation activity, respectively. The evaluation results showed that the graded catalyst loading process showed higher selectivity in HDS of FCC gasoline.

Abstract: Nowadays, ultraviolet (UV) irradiation heterogeneous Fenton-like reactions have widespread used in organic wastewater treatment. In this paper, Fe²⁺ and Cu²⁺ were load in Na-Y molecular sieve using impregnation method. Fe-Y, Cu-Y and Fe-Cu-Y catalysts were obtained. The Fe-Cu-Y catalyst showed good performance in the degradation of 6-nitryl wastewater. When the volume of 6-nitryl wastewater is 100 mL, the optimal reaction conditions were found to be 3mL of hydrogen peroxide, 7.5g of catalyst weight, 250W of UV power. Under these conditions, the degradation rate of COD_Cr can be up to 97.0%.

Abstract: A series of catalysts made of ruthenium loaded on γ-Al₂O₃ nanorods were prepared to study the effects of preparation procedure on their catalytic performances for hydrogenation CO₂ to formic acid. The catalysts are characterized by XRD, nitrogen adsorption measurement and H₂-TPR in detail. The results reveal that the catalytic activity is determined by the structure of supported ruthenium oxide species. The dispersion of RuO_x is influenced by the preparation procedures. Optimal activity of catalyst for the hydrogenation of CO₂ to formic acid is achieved over a γ-Al₂O₃ nanorods supported 2.0 wt% ruthenium catalyst, which is prepared by calcinations at 573 K in flowing air for 6h.

Abstract: In this paper, shaped titanium silicalite-1 (TS-1) zeolite catalysts from spray drying and extrusion were prepared and characterized by X-ray diffraction (XRD), infrared spectroscopy (FT-IR), nitrogen physisorption and laser diffraction techniques. The typical TS-1 MFI framework structures were both well retained during the shaping process. However, the extrudates gave dramatically decreased specific surface area, total pore volume and relatively poor catalytic performance in cyclohexanone ammoximation compared to spray samples and powdered TS-1, indicating that the spray method may be better choice for the reaction. Moreover, the stability and reusability of the spray shaped catalyst was evaluated by performing consecutives batch ammoximation runs with the same catalyst sample. After the fifth batch, it observed well stability of catalytic activity and particle size distribution.