Papers by Keyword: Hydrogenation

Abstract: The traditional method of preparing 0.5 wt.% nano Pd/C catalysts used for pure terephthalic acid(PTA) refining is the precipitate-reduction method, and this paper proposed the sol-gel method, in which the palladium colloid was firstly prepared, and followed by the load process onto the activated carbon. The activity and microstructure of catalysts were investigated by means of SEM, TEM, EDS，XRD and HPLC. It was found that the activity of catalyst with the sol-gel method was much higher than that with precipitate-reduction method. The preparation technology has less effects on the micostructure of Pd/C catalysts, while the palladium particles of catalyst obtained with sol-gel method are much finer and the relatively palladium content is much higher.These two factors contribute to the higher activity of Pd/C catalyst.

Abstract: A series of Pt₁₀₀ and bimetallic PtNi catalysts were prepared on various supports namely amorphous silica (Degussa), crystalline silica (Chempure) and cerium oxide (CeO₂). The samples were prepared via precipitation method using NaBH₄ as a reducing agent. H₂-TPR analysis revealed that total reduction of the metal salts to metal particles occurred during this stage. All catalysts were tested for the hydrogenation of benzene to cyclohexane. It was found that the catalysts exhibited a decrease in the catalytic reactivity in the order of amorphous silica, crystalline silica and CeO₂. This is mainly due to the surface area and acidity of the support. Comparison of the PtNi catalysts with their respective monometallic catalyst showed that only the PtNi prepared on Chempure exhibited an enhanced reactivity. This is due to alloying of PtNi. For catalysts prepared on Degussa, the low H₂-chemisorption properties as well as lack in Pt peak shift in the XRD profiles leads to the believe that Ni and Pt may exist separately. H₂-TPD analysis supports these findings.

Abstract: The nanosized RuB amorphous alloys with three different ruthenium contents supported on Al2O3 were prepared by means of impregnation, following the chemical reduction with KBH4 solution. The gas-phase benzene hydrogenation was used as a probe reaction to evaluate the catalytic activity of the prepared catalysts. The catalysts were characterized by BET, inductively coupled plasma (ICP), X-ray diffraction (XRD), and transmission electron micrograph (TEM). The experiment results show that the catalytic activity of the three amorphous alloy catalysts goes up first with the increasing of temperature and has a maximum at 443K; when the Ru loading amount is 0.24 %(wt.%) of the catalyst, which is very few, the conversion of benzene on RuB/Al₂O₃ amorphous alloy catalyst can reach to 99.50% at 443K.

Abstract: The Ni-Mo-P amorphous catalysts were prepared by chemical reduction method under different sonication conditions. The catalytic performance of the prepared catalysts in selective hydrogenation of nitrobenzene(NB) to aniline(AN) were characterized by XRD, BET, N₂-adsorption, H₂-TPR and H₂-TPD. The results show that the introduction of ultrasonic can improve the dispersion of the active sites in the catalyst, the particle size of the catalyst is also smaller than the regular prepared Ni-Mo-P amorphous catalyst. And the influences of the sonication power and time on the catalysts were discussed and compared. The optimal sonication condition is 70 W within 25 min, its optimal reaction time is 150 min.

Abstract: If the surface of the titanium chips (TC) was modified by thermal treatment under air atmosphere, it could be reused as catalyst support or photocatalytic materials. TC-supported CuO and ZnO catalysts were prepared by impregnation (IMP) method and co-precipitation (CP) method using cupric nitrate and zinc nitrate solution as precursors. Loading of CuO and ZnO on TC was 40.6wt% and 50.3wt%, respectively. The catalytic activity for CO₂ hydrogenation was investigated using a flow-typed reactor under various pressures. Conversion of carbon dioxide to methyl alcohol over the CuO-ZnO/TC catalyst by CP and IMP methods were ca. 22% and ca. 10%, respectively. Conversion of carbon dioxide over CuO-ZnO/TC catalyst by CP method was increased with increasing reaction temperature in ranging of 15atm to 30 atm. Maximum selectivity and yield to methyl alcohol over CuO-ZnO/TC catalyst at 250°C were ca. 90% at 20 atm and ca. 18.2% at 30 atm, respectively.

Abstract: A new method of sustainable ethanol synthesis by hydrogenating dimethyl oxalate (DMO), which is easily obtained from syngas, over a Cu/SiO₂ catalyst is proposed based on previous works. The experimental results indicate that the Cu/SiO₂ catalyst exhibited a high activity under the relative mild conditions of 270°C and 2MPa with ethanol selectivity as high as 88% and extremely high DMO conversion.

Abstract: The influence of hydrogenation on microstructure and tensile properties of Ti40 alloy has been investigated. The microstructure observation reveals that a new phase called η phase with FCC structure appears at the grainboundaries when the hydrogen content above 0.3 wt.%. With increasing hydrogen contents, the strength first increases and then decreases, and the ductility decreases as the specimens tensioned at both room temperature and 700oC. These phenomenons are resulted from the solution strengthening of hydrogen addition in Ti40 alloy with single β phase. As the hydrogen content increases, the fracture mode changes from dimple to cleavage fracture for specimens tensioned at room temperature. When tested at 700oC, the morphology of fracture surfaces in the specimens are all characterized by polygonal grains and the fractograph exhibits typically “sugar candy” brittle fracture for the specimen with 0.5wt% H.

Abstract: A series of CuO-ZnO-CeO₂-ZrO₂/HZSM-5 catalysts were prepared and characterized by XRD, H₂-TPR. CO₂ hydrogenation to DME was carried out in a fixed bed reactor to test the catalytic performance of Ce-modified CuO-ZnO-ZrO₂/HZSM-5 catalyst under the condition of GHSV=1800 h^-1, p=3.0 MPa and T=250°C. The results indicate that the added CeO₂ improved the performance of the bifunctional catalysts, the CO₂ conversion and DME selectivity were obviously improved. CuO-ZnO-CeO₂-ZrO₂/HZSM-5 catalyst with Ce to Zr molar ratio of 1/1 showed the highest activity for DME synthesis from CO₂ hydrogenation.

Abstract: Hydrogenation of phenanthrene (PHE HYD) was investigated over a commercial NiW/Al₂O₃ catalyst under practical reaction conditions. GC-MS analysis was utilized to identify the numerous products formed during PHE HYD. The products included dihydrophenanthrene (DHP), 1,2,3,4-tetrahydrophenanthrene (THP), sym-octahydrophenanthrene (1,8-OHP), asym-octahydrophenanthrene (1,10-OHP) and perhydrophenanthrene (PHP), but the cracking products were not found under the reaction conditions. The effects of operating conditions such as temperature, pressure and H₂/liquor on PHE HYD were tested in detail. It is found that temperature and pressure had remarkable effect on PHE HYD, but volume ratio of H2/liquor had little effect on PHE HYD at the observation range. The addition of decalin had a positive impact on PHE HYD; it could increase the conversion of PHE and the selectivity to PHP.

Abstract: This paper studied the preparation of chemical raw materials–methanol using blast furnace gas obtained from steel production process. The energy saving and emission reduction effect and the economic benefit brought by the co-hydrogenation process of a mixture of CO and CO2 (CHP) has been compared with those brought by the respective hydrogenation process of CO and CO2 (RHP). The result shows that the CHP brings more economic benefit than the RHP, and the CHP brings more energy saving and emission reduction effect than the RHP.